WorldWideScience

Sample records for modeling structure-property relationships

  1. Structure-property relationships in model polyolefins

    Science.gov (United States)

    Weimann, Peter Andrew

    Correlations between structure and properties were examined in a variety of model polyolefin blend and block copolymer systems. Anionic polymerization and catalytic hydrogenation were used to prepare the polymers, followed by characterization of structure and the properties of interest. Production of poly(vinylcyclohexane) (PVCH) through hydrogenation of poly(styrene), using a novel Pt/SiOsb2 catalyst, was examined in some detail. Kinetics were established through time sampling of reactions performed under a variety of conditions, followed by characterization of the extent of saturation. The Pt/SiOsb2 catalyst was quantitatively demonstrated to be more efficient than other heterogeneous hydrogenation catalysts for saturation of poly(styrene). Relationships between chain structure and miscibility were explored in blends of isotactic poly(propylene) (i-PP) with a series of model saturated polyolefins. An experimental correlation between conformational symmetry and miscibility in polyolefin blends guided synthesis of several model poly(ethylene/ethylethylene) random copolymers. Using small-angle neutron scattering, melt miscibility was demonstrated for "conformationally symmetric" blends of poly(ethylene/ethylethylene) random copolymers and i-PP, while "conformationally asymmetric" random copolymers phase separated from i-PP. Phase separated poly(ethylene) (PE) - PVCH block copolymers were employed in a study of crystallization of tethered PE chains in confined environments. In these materials, the glassy PVCH forced the PE to crystallize in geometries with well-defined spacing and connectivity. Effects of chain tethering were studied through comparison of "EV" diblocks to "VEV" triblocks. Increasing confinement, reflected by decreasing the domain spacing of the block copolymer, led to a reduction in crystallite size. The geometry and connectivity of the PE component also had a major influence on crystallization. Crystal growth was retarded in block copolymers where

  2. Modeling process-structure-property relationships for additive manufacturing

    Science.gov (United States)

    Yan, Wentao; Lin, Stephen; Kafka, Orion L.; Yu, Cheng; Liu, Zeliang; Lian, Yanping; Wolff, Sarah; Cao, Jian; Wagner, Gregory J.; Liu, Wing Kam

    2018-02-01

    This paper presents our latest work on comprehensive modeling of process-structure-property relationships for additive manufacturing (AM) materials, including using data-mining techniques to close the cycle of design-predict-optimize. To illustrate the processstructure relationship, the multi-scale multi-physics process modeling starts from the micro-scale to establish a mechanistic heat source model, to the meso-scale models of individual powder particle evolution, and finally to the macro-scale model to simulate the fabrication process of a complex product. To link structure and properties, a highefficiency mechanistic model, self-consistent clustering analyses, is developed to capture a variety of material response. The model incorporates factors such as voids, phase composition, inclusions, and grain structures, which are the differentiating features of AM metals. Furthermore, we propose data-mining as an effective solution for novel rapid design and optimization, which is motivated by the numerous influencing factors in the AM process. We believe this paper will provide a roadmap to advance AM fundamental understanding and guide the monitoring and advanced diagnostics of AM processing.

  3. Data-driven multi-scale multi-physics models to derive process-structure-property relationships for additive manufacturing

    Science.gov (United States)

    Yan, Wentao; Lin, Stephen; Kafka, Orion L.; Lian, Yanping; Yu, Cheng; Liu, Zeliang; Yan, Jinhui; Wolff, Sarah; Wu, Hao; Ndip-Agbor, Ebot; Mozaffar, Mojtaba; Ehmann, Kornel; Cao, Jian; Wagner, Gregory J.; Liu, Wing Kam

    2018-01-01

    Additive manufacturing (AM) possesses appealing potential for manipulating material compositions, structures and properties in end-use products with arbitrary shapes without the need for specialized tooling. Since the physical process is difficult to experimentally measure, numerical modeling is a powerful tool to understand the underlying physical mechanisms. This paper presents our latest work in this regard based on comprehensive material modeling of process-structure-property relationships for AM materials. The numerous influencing factors that emerge from the AM process motivate the need for novel rapid design and optimization approaches. For this, we propose data-mining as an effective solution. Such methods—used in the process-structure, structure-properties and the design phase that connects them—would allow for a design loop for AM processing and materials. We hope this article will provide a road map to enable AM fundamental understanding for the monitoring and advanced diagnostics of AM processing.

  4. Amino acid profiles and quantitative structure-property relationship models as markers for Merlot and Torrontés wines.

    Science.gov (United States)

    Duchowicz, Pablo R; Giraudo, Miguel A; Castro, Eduardo A; Pomilio, Alicia B

    2013-09-01

    Quantitative structure-property relationships (QSPRs) were applied to the aminograms obtained by HPLC in our laboratories for Torrontés and Merlot wines. Dragon theoretical descriptors were derived for a set of optimized amino acid structures with the purpose of establishing QSPR models. The statistical Replacement Method was used for designing the best multi-parametric linear regression models, which included structural features selected from a pool containing 1497 constitutional, topological, geometrical or electronic molecular descriptors. Predicted QSPR results were in good agreement with experimental amino acid profiles. The developed QSPR approach showed to be of practical value for distinguishing each wine varietal, and for calculating experimentally non-available amino acid concentrations of Torrontés and Merlot wines. It was also useful for assessing wine authenticity; the models were especially suitable for Merlot and Torrontés wines. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Quantitative structure-property relationships of electroluminescent ...

    Indian Academy of Sciences (India)

    Quantitative structure-property relationships of electroluminescent materials: Artificial neural networks and support vector machines to predict electroluminescence of organic molecules. ALANA FERNANDES GOLIN and RICARDO STEFANI. ∗. Laboratório de Estudos de Materiais (LEMAT), Instituto de Ciências Exatas e da ...

  6. Uniaxial Extensional Behavior of A--B--A Thermoplastic Elastomers: Structure-Properties Relationship and Modeling

    Science.gov (United States)

    Martinetti, Luca

    relation between the observed power-law exponent and molecular structure was established. The measured low-frequency response, originating from the incipient glass transition of the A domains, was exploited and extrapolated to lower frequencies via a sequential application of the fractional Maxwell model and the fractional Zener model. With only a few, physically meaningful material parameters a realistic description of the A--B--A self-similar relaxation was obtained over a frequency range much broader than the experimental window and not accessible via time-temperature superposition. The relationship between large-strain response and network structure of A--B--A triblocks was investigated, by examining (1) the effect of linear relaxation mechanisms on the tensile behavior, (2) the sources of elastic and viscoelastic nonlinearities, and (3) the strain rate dependence of the ultimate properties. For the first time in the literature, the complex high-dimensional rheological signature of chewing gum was analyzed, especially in response to nonlinear and unsteady deformations in both shear and extension. A unique rheological fingerprint was obtained that is sufficient to provide a new robust definition of chewing gum that is independent of specific molecular composition. (Abstract shortened by ProQuest.).

  7. A New Variable Selection Method Based on Mutual Information Maximization by Replacing Collinear Variables for Nonlinear Quantitative Structure-Property Relationship Models

    International Nuclear Information System (INIS)

    Ghasemi, Jahan B.; Zolfonoun, Ehsan

    2012-01-01

    Selection of the most informative molecular descriptors from the original data set is a key step for development of quantitative structure activity/property relationship models. Recently, mutual information (MI) has gained increasing attention in feature selection problems. This paper presents an effective mutual information-based feature selection approach, named mutual information maximization by replacing collinear variables (MIMRCV), for nonlinear quantitative structure-property relationship models. The proposed variable selection method was applied to three different QSPR datasets, soil degradation half-life of 47 organophosphorus pesticides, GC-MS retention times of 85 volatile organic compounds, and water-to-micellar cetyltrimethylammonium bromide partition coefficients of 62 organic compounds.The obtained results revealed that using MIMRCV as feature selection method improves the predictive quality of the developed models compared to conventional MI based variable selection algorithms

  8. A New Variable Selection Method Based on Mutual Information Maximization by Replacing Collinear Variables for Nonlinear Quantitative Structure-Property Relationship Models

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemi, Jahan B.; Zolfonoun, Ehsan [Toosi University of Technology, Tehran (Korea, Republic of)

    2012-05-15

    Selection of the most informative molecular descriptors from the original data set is a key step for development of quantitative structure activity/property relationship models. Recently, mutual information (MI) has gained increasing attention in feature selection problems. This paper presents an effective mutual information-based feature selection approach, named mutual information maximization by replacing collinear variables (MIMRCV), for nonlinear quantitative structure-property relationship models. The proposed variable selection method was applied to three different QSPR datasets, soil degradation half-life of 47 organophosphorus pesticides, GC-MS retention times of 85 volatile organic compounds, and water-to-micellar cetyltrimethylammonium bromide partition coefficients of 62 organic compounds.The obtained results revealed that using MIMRCV as feature selection method improves the predictive quality of the developed models compared to conventional MI based variable selection algorithms.

  9. Structure-property relationships of bismaleimides

    Science.gov (United States)

    Tenteris-Noebe, Anita Diane

    The purpose of this research was to control and systematically vary the network topology of bismaleimides through cure temperature and chemistry (addition of various coreactants) and subsequently attempt to determine structure-mechanical property relationships. Characterization of the bismaleimide structures by dielectric, rheological, and thermal analyses, and density measurements was subsequently correlated with mechanical properties such as modulus, yield strength, fracture energy, and stress relaxation. The model material used in this investigation was 4,4sp'-bismaleimidodiphenyl methane (BMI). BMI was coreacted with either 4,4sp'-methylene dianiline (MDA), o,osp'-diallyl bisphenol A (DABA) from Ciba Geigy, or diamino diphenyl sulfone (DDS). Three cure paths were employed: a low-temperature cure of 140sp°C where chain extension should predominate, a high-temperature cure of 220sp°C where both chain extension and crosslinking should occur simultaneously, and a low-temperature (140sp°C) cure followed immediately by a high-temperature (220sp°C) cure where the chain extension reaction or amine addition precedes BMI homopolymerization or crosslinking. Samples of cured and postcured PMR-15 were also tested to determine the effects of postcuring on the mechanical properties. The low-temperature cure condition of BMI/MDA exhibited the highest modulus values for a given mole fraction of BMI with the modulus decreasing with decreasing concentration of BMI. The higher elastic modulus is the result of steric hindrance by unreacted BMI molecules in the glassy state. The moduli values for the high- and low/high-temperature cure conditions of BMI/MDA decreased as the amount of diamine increased. All the moduli values mimic the yield strength and density trends. For the high-temperature cure condition, the room-temperature modulus remained constant with decreasing mole fraction of BMI for the BMI/DABA and BMI/DDS systems. Postcuring PMR-15 increases the modulus over that

  10. Quantitative structure-property relationships of electroluminescent ...

    Indian Academy of Sciences (India)

    Moreover, RMSE of support vector machine model is approximately half of RMSE observed for artificial neural networks model, which is significant from the point of view of model precision, as the dataset is very small. Thus, support vector machine is a good method to build QSPR models to predict the electroluminescence ...

  11. Structure-property relationships in eutectic composites

    Science.gov (United States)

    Hertzberg, R. W.

    1976-01-01

    The preparation of a composite material of eutectic composition directly from the molten state is investigated. The manufacture of eutectic composites by unidirectional solidification is reviewed, and it is shown how two-phase composite structures of given relative volume fraction can be produced with a range of particle sizes. Crystallographic relationships and the thermal stability of interfaces in controlled eutectic structures are examined, the mechanical behavior of aligned eutectic microstructures is discussed, and characteristics of eutectic composites having mechanical properties of engineering significance are evaluated. Specific properties of the Ni-Nb eutectic alloy are reviewed to demonstrate the effect of structure control (through directional solidification) on the mechanical response of a eutectic composite. It is noted that unidirectionally solidified eutectic composites possess highly aligned and thermally stable microstructures and also exhibit excellent combinations of strength and ductility to very high temperature levels.

  12. A modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model for predicting liquid viscosity of pure organic compounds

    International Nuclear Information System (INIS)

    Lee, Seongmin; Park, Kiho; Yang, Dae Ryook; Kwon, Yunkyung; Park, Taeyun

    2017-01-01

    Liquid viscosity is an important physical property utilized in engineering designs for transportation and processing of fluids. However, the measurement of liquid viscosity is not always easy when the materials have toxicity and instability. In this study, a modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model is suggested and analyzed in terms of its performance of prediction for liquid viscosity compared to the conventional SVRC-QSPR model and the other methods. The modification was conducted by changing the initial point from triple point to ambient temperature (293 K), and assuming that the liquid viscosity at critical temperature is 0 cP. The results reveal that the prediction performance of the modified SVRC-QSPR model is comparable to the other methods as showing 7.90% of mean absolute percentage error (MAPE) and 0.9838 of R 2 . In terms of both the number of components and the performance of prediction, the modified SVRC-QSPR model is superior to the conventional SVRC-QSPR model. Also, the applicability of the model is improved since the condition of the end points of the modified model is not so restrictive as the conventional SVRC-QSPR model.

  13. A modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model for predicting liquid viscosity of pure organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seongmin; Park, Kiho; Yang, Dae Ryook [Korea University, Seoul (Korea, Republic of); Kwon, Yunkyung; Park, Taeyun [ChemEssen Inc., Seoul (Korea, Republic of)

    2017-10-15

    Liquid viscosity is an important physical property utilized in engineering designs for transportation and processing of fluids. However, the measurement of liquid viscosity is not always easy when the materials have toxicity and instability. In this study, a modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model is suggested and analyzed in terms of its performance of prediction for liquid viscosity compared to the conventional SVRC-QSPR model and the other methods. The modification was conducted by changing the initial point from triple point to ambient temperature (293 K), and assuming that the liquid viscosity at critical temperature is 0 cP. The results reveal that the prediction performance of the modified SVRC-QSPR model is comparable to the other methods as showing 7.90% of mean absolute percentage error (MAPE) and 0.9838 of R{sup 2}. In terms of both the number of components and the performance of prediction, the modified SVRC-QSPR model is superior to the conventional SVRC-QSPR model. Also, the applicability of the model is improved since the condition of the end points of the modified model is not so restrictive as the conventional SVRC-QSPR model.

  14. Structure property relationships in various filled polymers

    Science.gov (United States)

    Yu, Jiong

    The toughness of impact modified poly(vinyl chloride) (PVC) compounds was examined using a modified Charpy test. Increasing impact speed resulted in a quasi-brittle to ductile transition in all PVC compounds. In the quasi-brittle region, a PVC of 56,000 Mw fractured through a craze-like damage zone that could be described by a modified Dugdale model. Furthermore, the same molecular weight PVC modified with either 10 pph chlorinated polyethylene (CPE) or 10 pph methylmethacrylate-butadiene-styrene (MBS) impact modifier also conformed to the Dugdale model with the craze-like damage zone. It was found that CPE effectively improved the impact performance of PVC by shifting the quasi-brittle to ductile transition to a higher loading rate. Compared to CPE, MBS was found to be a better impact modifier and resulted in a higher quasi-brittle to ductile transition loading rate in the same PVC matrix. Fracture initiation toughness of all the materials was described by the Hayes-Williams modification of the Dugdale model. The intrinsic brittle fracture energy obtained by extrapolation to zero craze length was determined only by the PVC matrix and was independent of the impact modifier. However, the kinetics of craze growth, and hence the response to rapid loading, depended on the impact modifier. Increasing molecular weight of the PVC resin resulted in a more complex damage zone that was not amendable to the Dugdale analysis. A new in-situ infusion method was used to incorporate small amounts (ca. 1wt%) of metal and metal oxide particles into a polymer matrix. Nano-sized particles were observed by both transmission electron microscopy (TEM) and atomic force microscopy (AFM). Oxygen (O2) and carbon dioxide (CO2) transport properties of the infused materials were investigated using a dynamic diffusion approach in which both testing and purge gases can be controlled. It was discovered that trace amounts (ca. 2%) of hydrogen (H2) in the purge gas was sufficient to considerably

  15. Tools to Understand Structural Property Relationships for Wood Cell Walls

    Science.gov (United States)

    Joseph E. Jakes; Daniel J. Yelle; Charles R. Frihart

    2011-01-01

    Understanding structure-property relationships for wood cell walls has been hindered by the complex polymeric structures comprising these cell walls and the difficulty in assessing meaningful mechanical property measurements of individual cell walls. To help overcome these hindrances, we have developed two experimental methods: 1) two-dimensional solution state nuclear...

  16. Structure/property relationships in non-linear optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Cole, J.M. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)]|[Durham Univ. (United Kingdom); Howard, J.A.K. [Durham Univ. (United Kingdom); McIntyre, G.J. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    The application of neutrons to the study of structure/property relationships in organic non-linear optical materials (NLOs) is described. In particular, charge-transfer effects and intermolecular interactions are investigated. Charge-transfer effects are studied by charge-density analysis and an example of one such investigation is given. The study of intermolecular interactions concentrates on the effects of hydrogen-bonding and an example is given of two structurally similar molecules with very disparate NLO properties, as a result of different types of hydrogen-bonding. (author). 3 refs.

  17. Structure-Property Relationships of Solids in Pharmaceutical Processing

    Science.gov (United States)

    Chattoraj, Sayantan

    Pharmaceutical development and manufacturing of solid dosage forms is witnessing a seismic shift in the recent years. In contrast to the earlier days when drug development was empirical, now there is a significant emphasis on a more scientific and structured development process, primarily driven by the Quality-by-Design (QbD) initiatives of US Food and Drug Administration (US-FDA). Central to such an approach is the enhanced understanding of solid materials using the concept of Materials Science Tetrahedron (MST) that probes the interplay between four elements, viz., the structure, properties, processing, and performance of materials. In this thesis work, we have investigated the relationships between the structure and those properties of pharmaceutical solids that influence their processing behavior. In all cases, we have used material-sparing approaches to facilitate property assessment using very small sample size of materials, which is a pre-requisite in the early stages of drug development when the availability of materials, drugs in particular, is limited. The influence of solid structure, either at the molecular or bulk powder levels, on crystal plasticity and powder compaction, powder flow, and solid-state amorphization during milling, has been investigated in this study. Through such a systematic evaluation, we have captured the involvement of structure-property correlations within a wide spectrum of relevant processing behaviors of pharmaceutical solids. Such a holistic analysis will be beneficial for addressing both regulatory and scientific issues in drug development.

  18. Meteorite Unit Models for Structural Properties

    Science.gov (United States)

    Agrawal, Parul; Carlozzi, Alexander A.; Karajeh, Zaid S.; Bryson, Kathryn L.

    2017-10-01

    To assess the threat posed by an asteroid entering Earth’s atmosphere, one must predict if, when, and how it fragments during entry. A comprehensive understanding of the asteroid material properties is needed to achieve this objective. At present, the meteorite material found on earth are the only objects from an entering asteroid that can be used as representative material and be tested inside a laboratory. Due to complex composition, it is challenging and expensive to obtain reliable material properties by means of laboratory test for a family of meteorites. In order to circumvent this challenge, meteorite unit models are developed to determine the effective material properties including Young’s modulus, compressive and tensile strengths and Poisson’s ratio, that in turn would help deduce the properties of asteroids. The meteorite unit model is a representative volume that accounts for diverse minerals, porosity, cracks and matrix composition.The Young’s Modulus and Poisson’s Ratio in the meteorite units are calculated by performing several hundreds of Monte Carlo simulations by randomly distributing the various phases inside these units. Once these values are obtained, cracks are introduced in these units. The size, orientation and distribution of cracks are derived by CT-scans and visual scans of various meteorites. Subsequently, simulations are performed to attain stress-strain relations, strength and effective modulus values in the presence of these cracks. The meteorite unit models are presented for H, L and LL ordinary chondrites, as well as for terrestrial basalt. In the case of the latter, data from the simulations is compared with experimental data to validate the methodology. These meteorite unit models will be subsequently used in fragmentation modeling of full scale asteroids.

  19. Structure-property relationships of flexible polyurethane foams

    Science.gov (United States)

    Aneja, Ashish

    This study examined several features of flexible polyurethane foams from a structure-property perspective. A major part of this dissertation addresses the issue of connectivity of the urea phase and its influence on mechanical and viscoelastic properties of flexible polyurethane foams and their plaque counterparts. Lithium salts (LiCl and LiBr) were used as additives to systematically alter the phase separation behavior, and hence the connectivity of the urea phase at different scale lengths. Macro connectivity, or the association of the large scale urea rich aggregates typically observed in flexible polyurethane foams was assessed using SAXS, TEM, and AFM. These techniques showed that including a lithium salt in the foam formulation suppressed the formation of the urea aggregates and thus led to a loss in the macro level connectivity of the urea phase. WAXS and FTIR were used to demonstrate that addition of LiCl or LiBr systematically disrupted the local ordering of the hard segments within the microdomains, i.e., it led to a reduction of micro level connectivity or the regularity in segmental packing of the urea phase. Based on these observations, the interaction of the lithium salt was thought to predominantly occur with the urea hard segments, and this hypothesis was confirmed using quantum mechanical calculations. Another feature of this research investigated model trisegmented polyurethanes based on monofunctional polyols, or "monos", with water-extended toluene diisocyanate (TDI) based hard segments. The formulations of the monol materials were maintained similar to those of flexible polyurethane foams with the exceptions that the conventional polyol was substituted by an oligomeric monofunctional polyether of ca. 1000 g/mol molecular weight. Plaques formed from these model systems were shown to be solid materials even at their relatively low molecular weights of 3000 g/mol and less, AFM phase images, for the first time, revealed the ability of the hard

  20. Structure-property relationships of multiferroic materials: A nano perspective

    Science.gov (United States)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT

  1. Models for Prediction of Structural Properties of Palmnut Fibre ...

    African Journals Online (AJOL)

    An analytical study was carried out to investigate the structural properties of palmnut fibre reinforced cement-based composites. Explicit expressions were derived for the flexural, compressive and elongation behavior of composites using a two-phase constitutive model and verified using results obtained from literature.

  2. Relationships between Soil and Vegetation Structural Properties of ...

    African Journals Online (AJOL)

    The effects of soil on vegetation structural attributes (tree density, tree height, tree diameter, basal area and estimated aboveground biomass) of a secondary forest following the abandonment of a degraded rubber plantation in Orogun area of Delta state Nigeria was studied using the multiple linear regression model.

  3. Structure-Property Relationship in Metal Carbides and Bimetallic Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jingguan [University of Delaware

    2014-03-04

    The primary objective of our DOE/BES sponsored research is to use carbide and bimetallic catalysts as model systems to demonstrate the feasibility of tuning the catalytic activity, selectivity and stability. Our efforts involve three parallel approaches, with the aim at studying single crystal model surfaces and bridging the “materials gap” and “pressure gap” between fundamental surface science studies and real world catalysis. The utilization of the three parallel approaches has led to the discovery of many intriguing catalytic properties of carbide and bimetallic surfaces and catalysts. During the past funding period we have utilized these combined research approaches to explore the possibility of predicting and verifying bimetallic and carbide combinations with enhanced catalytic activity, selectivity and stability.

  4. Predicting adsorption of aromatic compounds by carbon nanotubes based on quantitative structure property relationship principles

    Science.gov (United States)

    Rahimi-Nasrabadi, Mehdi; Akhoondi, Reza; Pourmortazavi, Seied Mahdi; Ahmadi, Farhad

    2015-11-01

    Quantitative structure property relationship (QSPR) models were developed to predict the adsorption of aromatic compounds by carbon nanotubes (CNTs). Five descriptors chosen by combining self-organizing map and stepwise multiple linear regression (MLR) techniques were used to connect the structure of the studied chemicals with their adsorption descriptor (K∞) using linear and nonlinear modeling techniques. Correlation coefficient (R2) of 0.99 and root-mean square error (RMSE) of 0.29 for multilayered perceptron neural network (MLP-NN) model are signs of the superiority of the developed nonlinear model over MLR model with R2 of 0.93 and RMSE of 0.36. The results of cross-validation test showed the reliability of MLP-NN to predict the K∞ values for the aromatic contaminants. Molar volume and hydrogen bond accepting ability were found to be the factors much influencing the adsorption of the compounds. The developed QSPR, as a neural network based model, could be used to predict the adsorption of organic compounds by CNTs.

  5. Pathways to Structure-Property Relationships of Peptide-Materials Interfaces: Challenges in Predicting Molecular Structures.

    Science.gov (United States)

    Walsh, Tiffany R

    2017-07-18

    challenges in their successful application to model the biotic-abiotic interface, related to several factors. For instance, simulations require a plausible description of the chemistry and the physics of the interface, which comprises two very different states of matter, in the presence of liquid water. Also, it is essential that the conformational ensemble be comprehensively characterized under these conditions; this is especially challenging because intrinsically disordered peptides do not typically admit one single structure or set of structures. Moreover, a plausible structural model of the substrate is required, which may require a high level of detail, even for single-element materials such as Au surfaces or graphene. Developing and applying strategies to make credible predictions of the conformational ensemble of adsorbed peptides and using these to construct structure-property relationships of these interfaces have been the goals of our efforts. We have made substantial progress in developing interatomic potentials for these interfaces and adapting advanced conformational sampling approaches for these purposes. This Account summarizes our progress in the development and deployment of interfacial force fields and molecular simulation techniques for the purpose of elucidating these insights at biomolecule-materials interfaces, using examples from our laboratories ranging from noble-metal interfaces to graphitic substrates (including carbon nanotubes and graphene) and oxide materials (such as titania). In addition to the well-established application areas of plasmonic materials, biosensing, and the production of medical implant materials, we outline new directions for this field that have the potential to bring new advances in areas such as energy materials and regenerative medicine.

  6. Adsorption of s-triazines onto polybenzimidazole: A quantitative structure-property relationship investigation

    International Nuclear Information System (INIS)

    D'Archivio, Angelo Antonio; Incani, Angela; Mazzeo, Pietro; Ruggieri, Fabrizio

    2009-01-01

    The adsorption of 25 symmetric triazines (s-triazines) on polybenzimidazole (PBI) beads is investigated under equilibrium (batch) conditions. The observed adsorption isotherms of the selected compounds are accurately described by the Freundlich model, while the agreement between the Langmuir model and the experimental data is moderately worse, which seems to reflect the heterogeneous meso- and micro-porosity of PBI and polydispersion in the interaction mechanism. Methylthio- and methoxytriazines exhibit a greater adsorption tendency as compared with chlorotriazines, moreover, progressive dealkylation of amino groups results in a progressive increase of triazine uptake on PBI. Based on these evidences, the adsorption mechanism seems to be governed by a combination of π-π and hydrogen-bonding interactions. Genetic algorithm (GA) variable selection and multilinear regression (MLR) are combined in order to describe the effect of triazine structure on the extraction performance of PBI according to the quantitative structure-property relationship (QSPR) method. q max , the amount of triazine adsorbed per weight unit of PBI assuming homogeneous monolayer (Langmuir) mechanism, exhibits a great variability within the set of investigated triazines and is the quantity here modelled by QSPR. On the other hand, the Freundlich constant, K F , which expresses the adsorption efficiency under multilayer heterogeneous conditions, even if markedly increases passing from chloro- to methylthio- or methoxytriazines, is less noticeably affected by the fine details of the adsorbate structure, as the number or nature of alkyl fragments bound to the amino groups. To quantitatively relate q max with the triazine structure GA-MLR analysis is performed on the set of 1664 theoretical molecular descriptors provided by the software Dragon. Finally, a four-dimensional QSPR model is selected based on leave-one-out cross-validation and its prediction ability is further tested on four

  7. Structure-Property-Function Relationship in Humic Substances to Explain the Biological Activity in Plants

    Science.gov (United States)

    García, Andrés Calderín; de Souza, Luiz Gilberto Ambrosio; Pereira, Marcos Gervasio; Castro, Rosane Nora; García-Mina, José María; Zonta, Everaldo; Lisboa, Francy Junior Gonçalves; Berbara, Ricardo Luis Louro

    2016-02-01

    Knowledge of the structure-property-function relationship of humic substances (HSs) is key for understanding their role in soil. Despite progress, studies on this topic are still under discussion. We analyzed 37 humic fractions with respect to their isotopic composition, structural characteristics, and properties responsible for stimulating plant root parameters. We showed that regardless of the source of origin of the carbon (C3 or C4), soil-extracted HSs and humic acids (HAs) are structurally similar to each other. The more labile and functionalized HS fraction is responsible for root emission, whereas the more recalcitrant and less functionalized HA fraction is related to root growth. Labile structures promote root stimulation at lower concentrations, while recalcitrant structures require higher concentrations to promote a similar stimulus. These findings show that lability and recalcitrance, which are derived properties of humic fractions, are related to the type and intensity of their bioactivity. In summary, the comparison of humic fractions allowed a better understanding of the relationship between the source of origin of plant carbon and the structure, properties, and type and intensity of the bioactivity of HSs in plants. In this study, scientific concepts are unified and the basis for the agronomic use of HSs is established.

  8. Atomic-level structure and structure-property relationship in metallic glass

    Science.gov (United States)

    Cheng, Yongqiang

    One of the key tasks in material science is to understand the structure and structure-property relationship. The recently emerging bulk metallic glasses (BMGs) have demonstrated unique properties, especially intriguing mechanical properties such as their high strength and high propensity to localize deformation in shear bands. However, a comprehensive understanding of the structure of BMGs has been hindered by the complexity of these amorphous materials. Even more challenging is the structure-property correlation, which has been well established in crystals but has been seriously lacking for BMGs. This thesis presents a systematic study of the atomic-level structures of two representative BMGs, Cu-Zr and Cu-Zr-Al. The interpenetrating Cu-centered icosahedral clusters have been identified to be the primary structural feature. The fraction of icosahedra increases with increasing Cu or Al contents, and with decreasing cooling rate. The effect of Al in improving the icosahedral order is two-fold: the geometric effect due to the atomic-size mismatch and the chemical effect originated from the Cu-Al bond shortening. The resolved structure is used to study the structure-property relationship. The full icosahedra are found to be responsible for the dynamical slowdown of the supercooled liquid, which underlies the non-Arrhenius behavior, and explains the composition dependence of glass transition temperature, glass forming ability, and the room temperature strength. By simulated deformation, the initiation of plasticity and tendency for strain localization are also investigated. The full icosahedra are found to be the most rigid and resistant cluster with solid-like character, while the unstable clusters with liquid-like character serve as the fertile sites for initiating shear transformations. In addition, the elastic moduli are calculated and analyzed, and the origins of the different configurational dependence of shear modulus (G) and bulk modulus ( B) are explained. The

  9. Structure-Property Relationships of Polymer Brushes in Restricted Geometries and their Utilization as Ultra-Low Lubricants

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, Tonya Lynn [Univ. of California, Davis, CA (United States); Faller, Roland [Univ. of California, Davis, CA (United States)

    2015-09-28

    Though polymer films are widely used to modify or tailor the physical, chemical and mechanical properties of interfaces in both solid and liquid systems, the rational design of interface- or surface-active polymer modifiers has been hampered by a lack of information about the behavior and structure-property relationships of this class of molecules. This is especially true for systems in which the role of the polymer is to modify the interaction between two solid surfaces in intimate contact and under load, to cause them to be mechanically coupled (e.g. to promote adhesion and wetting) or to minimize their interaction (e.g. lubrication, colloidal stabilization, etc.). Detailed structural information on these systems has largely been precluded by the many difficulties and challenges associated with direct experimental measurements of polymer structure in these geometries. As a result, many practitioners have been forced to employ indirect measurements or rely wholly on theoretical modeling. This has resulted in an incomplete understanding of the structure-property relationships, which are relied upon for the rational design of improved polymer modifiers. Over the course of this current research program, we made direct measurements of the structure of polymers at the interface between two solid surfaces under confinement and elucidated the fundamental physics behind these phenomena using atomistic and coarse grained simulations. The research has potential to lead to new lubricants and wear reducing agents to improve efficiency.

  10. Structure-property relationships in the design, assembly and applications of polyelectrolyte multilayer thin films

    Science.gov (United States)

    Rmaile, Hassan H.

    Ultrathin films consisting of an alternating sequence of positively and negatively charged polyelectrolytes have been prepared by means of the electrostatic layer-by-layer sequential assembly technique. To augment their typical applications in the water treatment, personal care as well as the pulp and paper industry, the structure and the design of these polyelectrolytes were tailored synthetically to satisfy the requirements of different types of applications. Some were used for surface modifications, hydrophobic and hydrophilic coatings, corrosion protection, conducting and biocompatible surfaces. Others were found to be very efficient for membrane and chromatographic applications. The ease with which these multilayer coatings can be constructed, their robustness and stability make them very good candidates for industrial applications. The dissertation focuses mainly on the structure-property relationships of these polyelectrolytes and their corresponding thin films. Various polyelectrolytes were synthesized or modified in a strategic approach and gave novel and promising properties. Some of them exhibited permeabilities that were higher than any membranes reported in the literature. Also, some are potentially very useful for designing drug delivery systems such as tablets or encapsulations since they were shown to control the permeability of sample drugs and vitamins very efficiently based on their sensitivity to pH changes. Other synthesized polyelectrolytes proved to be very effective in preventing protein adsorption or promoting cell growth and differentiation. Some systems were very useful as robust stationary phases for simple chiral separations in capillary electrochromatography. Along with modifications and improvements, the approach might one day be applied commercially for chiral separations using high performance liquid chromatography and replace currently used stationary phases. Last but not least, the potential for these polyelectrolytes and their

  11. Structure-property relationships in self-assembling peptide hydrogels, homopolypeptides and polysaccharides

    Science.gov (United States)

    Hule, Rohan A.

    The main objective of this dissertation is to investigate quantitative structure-property relationships in a variety of molecular systems including de novo designed peptides, peptide amphiphiles, polysaccharides and high molecular weight polypeptides. Peptide molecules consisting of 20 amino acids were designed to undergo thermally triggered intramolecular folding into asymmetric beta-hairpins and intermolecular self-assembly via a strand swapping mechanism into physically crosslinked fibrillar hydrogels. The self-assembly mechanism was confirmed by multiple characterization techniques such as circular dichroism and FITR spectroscopy, atomic force and transmission electron microscopy and small angle neutron scattering. Three distinct fibrillar nanostructures, i.e. non-twisted, twisted and laminated were produced, depending on the degree of strand asymmetry and peptide registry. Differences in the fibrillar morphology have a direct consequence on the mechanical properties of the hydrogels, with the laminated hydrogels exhibiting a significantly higher elastic modulus as compared to the twisted or non-twisted fibrillar hydrogels. SANS and cryo-TEM data reveal that the self-assembled fibrils form networks that are fractal in nature. Models employed to elucidate the fractal behavior can relate changes in the correlation lengths, low q (network), and high q (fibrillar) fractal exponents to the distinct fibrillar nanomorphology. The fractal dimension of the networks varies significantly, from a mass to a surface fractal and can be directly related to the local fibrillar morphology and changes in the peptide concentration. Transitions in the fractal behavior seen in the high q regime can be attributed to self-assembly kinetics. An identical model can be used to establish a direct correlation between the bulk properties and changes in both, the network density and underlying morphology, of a modified peptide-based hydrogel. As in the case of asymmetric peptides, changes in

  12. Localized surface plasmon resonance induced structure-property relationships of metal nanostructures

    Science.gov (United States)

    Vilayurganapathy, Subramanian

    The confluence of nanotechnology and plasmonics has led to new and interesting phenomena. The industrial need for fast, efficient and miniature devices which constantly push the boundaries on device performance tap into the happy marriage between these diverse fields. Designing devices for real life application that give superior performance when compared with existing ones are enabled by a better understanding of their structure-property relationships. Among all the design constraints, without doubt, the shape and size of the nanostructure along with the dielectric medium surrounding it has the maximum influence on the response and thereby the performance of the device. Hence a careful study of the above mentioned parameters is of utmost importance in designing efficient devices. In this dissertation, we synthesize and study the optical properties of nanostructures of different shapes and size. In particular, we estimated the plasmonic near field enhancement via surface-enhanced Raman scattering (SERS) and 2-photon Photoemission electron microscopy (2P-PEEM). We synthesized the nanostructures using four different techniques. One synthesis technique, the thermal growth method was employed to grow interesting Ag and Au nanostructures on Si. The absence of toxic chemicals during nanostructure synthesis via the thermal growth technique opens up myriad possibilities for applications in the fields of biomedical science, bioengineering, drug delivery among others along with the huge advantage of being environment friendly. The other three synthesis techniques (ion implantation, Electrodeposition and FIB lithography) were chosen with the specific goal of designing novel plasmonic metal, metal hybrid nanostructures as photocathode materials in next generation light sources. The synthesis techniques for these novel nanostructures were dictated by the requirement of high quantum efficiency, robustness under constant irradiation and coherent unidirectional electron emission

  13. Absorbability, Mechanism and Structure-Property Relationship of Three Phenolic Acids from the Flowers of Trollius chinensis

    Directory of Open Access Journals (Sweden)

    Xiu-Wen Wu

    2014-11-01

    Full Text Available The absorption properties, mechanism of action, and structure-property relationship of three phenolic acids isolated from the flowers of Trollius chinensis Bunge, namely, proglobeflowery acid (PA, globeflowery acid (GA and trolloside (TS, were investigated using the human Caco-2 cell monolayer model. The results showed that these three phenolic acids were transported across the Caco-2 cell monolayer in a time and concentration dependent manner at the Papp level of 10−5 cm/s, and their extent of absorption correlated with their polarity and molecular weight. In conclusion, all three of these compounds were easily absorbed through passive diffusion, which implied their high bioavailability and significant contribution to the effectiveness of T. chinensis.

  14. Structure/property relationships in polymer membranes for water purification and energy applications

    Science.gov (United States)

    Geise, Geoffrey

    Providing sustainable supplies of purified water and energy is a critical global challenge for the future, and polymer membranes will play a key role in addressing these clear and pressing global needs for water and energy. Polymer membrane-based processes dominate the desalination market, and polymer membranes are crucial components in several rapidly developing power generation and storage applications that rely on membranes to control rates of water and/or ion transport. Much remains unknown about the influence of polymer structure on intrinsic water and ion transport properties, and these relationships must be developed to design next generation polymer membrane materials. For desalination applications, polymers with simultaneously high water permeability and low salt permeability are desirable in order to prepare selective membranes that can efficiently desalinate water, and a tradeoff relationship between water/salt selectivity and water permeability suggests that attempts to prepare such materials should rely on approaches that do more than simply vary polymer free volume. One strategy is to functionalize hydrocarbon polymers with fixed charge groups that can ionize upon exposure to water, and the presence of charged groups in the polymer influences transport properties. Additionally, in many emerging energy applications, charged polymers are exposed to ions that are very different from sodium and chloride. Specific ion effects have been observed in charged polymers, and these effects must be understood to prepare charged polymers that will enable emerging energy technologies. This presentation discusses research aimed at further understanding fundamental structure/property relationships that govern water and ion transport in charged polymer films considered for desalination and electric potential field-driven applications that can help address global needs for clean water and energy.

  15. Probing structure-property relationships in perpendicularly magnetized Fe/Cu(001) using MXLD and XPD

    Energy Technology Data Exchange (ETDEWEB)

    Cummins, T.R.; Waddill, G.D. [Univ. of Missouri, Rolla, MO (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Magnetic X-ray Linear Dichroism (MXLD) in Photoelectron Spectroscopy and X-Ray Photoelectron Diffraction (XPD) of the Fe 3p core level have been used to probe the magnetic structure-property relationships of perpendicularly magnetized Fe/Cu(001), in an element-specific fashion. A strong MEXLD effect was observed in the high resolution photoelectron spectroscopy of the Fe 3p at {open_quotes}normal{close_quotes} emission and was used to follow the loss of perpendicular ferromagnetic ordering as the temperature was raised toward room temperature. In parallel with this, {open_quotes}Forward Focussing{close_quotes} in XPD was used as a direct measure of geometric structure in the overlayer. These results and the implications of their correlation will be discussed. Additionally, an investigation of the effect of Mn doping of the Fe/Cu(001) will be described. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  16. Structure-property relationship in core-shell rubber toughened epoxy nanocomposites

    Science.gov (United States)

    Gam, Ki Tak

    The structure-property relationships of epoxy nanocomposites with inorganic layer-structure nanofillers have been studied to obtain the fundamental understanding of the role of nanofillers and the physics of polymer nanocomposites in this dissertation. Several polymer nanocomposite systems with modified montmorillonite (MMT) or alpha-zirconium phosphate (ZrP) nanofillers were prepared with epoxy matrices of different ductility and properties. The successful nanofiller's exfoliations were confirmed with X-ray diffraction and transmission electronic microscopy (TEM). Dynamic mechanical analysis (DMA) on the prepared epoxy nanocomposites revealed the significant increase in rubbery plateau moduli of the epoxy nanocomposite systems above Tg, as high as 4.5 times, and tensile test results showed improved modulus by the nanofiller addition, while the fracture toughness was not affected or slightly decreased by nanofillers. The brittle epoxy nanocomposite systems were toughened with core shell rubber (CSR) particles and showed remarkable increase in fracture toughness (KIC) value up to 270%. The CSR toughening is more effective at ductile matrices, and TEM observation indicates that major toughening mechanisms induced by the CSR addition involve a large scale CSR cavitation, followed by massive shear deformation of the matrix.

  17. Structure-properties relationships of polyhedral oligomeric silsesquioxane (POSS filled PS nanocomposites

    Directory of Open Access Journals (Sweden)

    J. J. Schwab

    2012-07-01

    Full Text Available The polyhedral oligomeric silsesquioxane (POSS additivated polystyrene (PS based nanocomposites were prepared by melt processing and the structure-properties relationships of the POSS-PS systems were compared to those of the neat PS. In order to investigate the effect of these structural parameters on the final properties of the polymer nanocomposites, five different kinds of POSS samples were used, in particular, POSS with different inorganic cage and with different organic pendent groups. The rheological investigation suggests clearly that the POSS acts as a plasticizer and that the processability of the PS was positively modified. The affinity between the POSS samples and the PS matrix was estimated by the calculated theoretical solubility parameters, considering the Hoy’s method and by morphology analysis. Minor difference between the solubility parameter of POSS and the matrix means better compatibility and no aggregation tendency. Furthermore, the POSS loading leads to a decrease of the rigidity, of the glass transition temperature and of the damping factor of the nanocomposite systems. The loading of different POSS molecules with open cage leads to a more pronounced effect on all the investigated properties that the loading of the POSS molecules with closed cage. Moreover, the melt properties are significantly influenced by the type of inorganic framework, by the type of the pendent organic groups and by the interaction between the POSS organic groups and the host matrix, while, the solid state properties appears to be influenced more by the kind of cage.

  18. Thermoelectric plastics: from design to synthesis, processing and structure-property relationships.

    Science.gov (United States)

    Kroon, Renee; Mengistie, Desalegn Alemu; Kiefer, David; Hynynen, Jonna; Ryan, Jason D; Yu, Liyang; Müller, Christian

    2016-11-07

    Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure-property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer.

  19. Structural properties of silver nanoparticle agglomerates based on transmission electron microscopy: relationship to particle mobility analysis

    International Nuclear Information System (INIS)

    Shin, Weon Gyu; Wang Jing; Mertler, Michael; Sachweh, Bernd; Fissan, Heinz; Pui, David Y. H.

    2009-01-01

    In this work, the structural properties of silver nanoparticle agglomerates generated using condensation and evaporation method in an electric tube furnace followed by a coagulation process are analyzed using Transmission Electron Microscopy (TEM). Agglomerates with mobility diameters of 80, 120, and 150 nm are sampled using the electrostatic method and then imaged by TEM. The primary particle diameter of silver agglomerates was 13.8 nm with a standard deviation of 2.5 nm. We obtained the relationship between the projected area equivalent diameter (d pa ) and the mobility diameter (d m ), i.e., d pa = 0.92 ± 0.03 d m for particles from 80 to 150 nm. We obtained fractal dimensions of silver agglomerates using three different methods: (1) D f = 1.84 ± 0.03, 1.75 ± 0.06, and 1.74 ± 0.03 for d m = 80, 120, and 150 nm, respectively from projected TEM images using a box counting algorithm; (2) fractal dimension (D fL ) = 1.47 based on maximum projected length from projected TEM images using an empirical equation proposed by Koylu et al. (1995) Combust Flame 100:621-633; and (3) mass fractal-like dimension (D fm ) = 1.71 theoretically derived from the mobility analysis proposed by Lall and Friedlander (2006) J Aerosol Sci 37:260-271. We also compared the number of primary particles in agglomerate and found that the number of primary particles obtained from the projected surface area using an empirical equation proposed by Koylu et al. (1995) Combust Flame 100:621-633 is larger than that from using the relationship, d pa = 0.92 ± 0.03 d m or from using the mobility analysis.

  20. Structure-Property Relationships of Small Organic Molecules as a Prelude to the Teaching of Polymer Science

    Science.gov (United States)

    Wnek, Gary E.

    2017-01-01

    Small organic molecules offer a rich opportunity to discuss the interplay of chemical structure with properties such as the melting point and phenomena such as glass formation and can form the basis of fundamental considerations of structure-property relationships in macromolecules. Of particular importance are thermal transitions, specifically…

  1. Unraveling Structure-Property Relationships in Polymer Blends for Intelligent Materials Design

    Science.gov (United States)

    Irwin, Matthew Tyler

    Block polymers provide an accessible route to structured, composite materials by combining two or more components with disparate mechanical, chemical, and electrical properties into a single bulk material with nanoscale domains. However, the characteristic lengthscale of these systems is limited, and the choice of components is restricted to those that are able to undergo microstructural ordering at accessible temperatures. This thesis details routes to overcoming these limitations through the addition of a lithium salt, a blend of homopolymers, or both. Chapter 2 describes a study wherein complex sphere phases such as the Frank-Kasper sigma phase can be observed in otherwise disordered asymmetric block polymers through the addition of a lithium salt. Chapter 3 discusses the development and characterization of a ternary polymer blend of an AB diblock copolymer and A and B homopolymers doped with a lithium salt. Detailed characterization showed that doping blends that are otherwise disordered with lithium salt induced microstructural ordering and largely recovers the phase behavior of traditional ternary polymer blends. A systematic study of the ionic conductivity of the blends at a fixed salt concentration demonstrates that, at a given composition, disordered, yet highly structured blends consistently exhibit better conductivity than polycrystalline morphologies with long range order. Chapter 4 extends the methodology of Chapter 3 and details a systematic study of the effects of cross-linker concentration on the performance of polymer electrolyte membranes produced via polymerization-induced microphase separation that exhibit a highly structured, globally disordered microstructure. Finally, Chapter 5 details efforts to develop a water filtration membrane using a polyethylene template derived from a polymeric bicontinuous microemulsion. Throughout all of this work, the goal is to better understand structure-property relationships at the molecular level in order to

  2. Structure-property relationship of quinuclidinium surfactants--Towards multifunctional biologically active molecules.

    Science.gov (United States)

    Skočibušić, Mirjana; Odžak, Renata; Štefanić, Zoran; Križić, Ivana; Krišto, Lucija; Jović, Ozren; Hrenar, Tomica; Primožič, Ines; Jurašin, Darija

    2016-04-01

    Motivated by diverse biological and pharmacological activity of quinuclidine and oxime compounds we have synthesized and characterized novel class of surfactants, 3-hydroxyimino quinuclidinium bromides with different alkyl chains lengths (CnQNOH; n=12, 14 and 16). The incorporation of non conventional hydroxyimino quinuclidinium headgroup and variation in alkyl chain length affects hydrophilic-hydrophobic balance of surfactant molecule and thereby physicochemical properties important for its application. Therefore, newly synthesized surfactants were characterized by the combination of different experimental techniques: X-ray analysis, potentiometry, electrical conductivity, surface tension and dynamic light scattering measurements, as well as antimicrobial susceptibility tests. Comprehensive investigation of CnQNOH surfactants enabled insight into structure-property relationship i.e., way in which the arrangement of surfactant molecules in the crystal phase correlates with their solution behavior and biologically activity. The synthesized CnQNOH surfactants exhibited high adsorption efficiency and relatively low critical micelle concentrations. In addition, all investigated compounds showed very potent and promising activity against Gram-positive and clinically relevant Gram-negative bacterial strains compared to conventional antimicrobial agents: tetracycline and gentamicin. The overall results indicate that bicyclic headgroup with oxime moiety, which affects both hydrophilicity and hydrophobicity of CnQNOH molecule in addition to enabling hydrogen bonding, has dominant effect on crystal packing and physicochemical properties. The unique structural features of cationic surfactants with hydroxyimino quinuclidine headgroup along with diverse biological activity have made them promising structures in novel drug discovery. Obtained fundamental understanding how combination of different functionalities in a single surfactant molecule affects its physicochemical

  3. Hybrid Mixed Media Nonwovens: An Investigation of Structure-Property Relationships

    Science.gov (United States)

    Hollowell, Kendall Birckhead

    There have been myriad studies on utilizing bicomponent splittables produced through spunbond/spunlace processes. These production methods have proven to yield microfibers which increase the surface area of the nonwoven structures. There has been recent focus on studying the microfibers within these nonwoven structures as well as using a multiplicity of deniers of fibers within the nonwoven. There have also been studies on producing nonwovens with fibers of differing cross-sectional shapes and diameters. The purpose of this study is to examine the properties of a nonwoven structure, marrying the concepts of multi-denier fibers with multi-shaped fibers in two configurations: three-layer and alternating. The basis for this study will be US Patent 6,964,931 B2 "Method of making Continuous Filament Web with Statistical Filament Distribution" as well as US Patent 7,981,336 B2 "Process of Making Mixed Fibers and Nonwoven Fabrics". This study addresses the melt-spinning and hydroentanglement of nonwoven webs made from bicomponent fibers in three-layer and alternating configurations. The bicomponent cross-sections that will be used include 16-segmented pie and 7-islands-in-the-sea. In this study the establishment of the utility of mixed media nonwovens will take place through property and structure analysis in order to determine the inherent properties of the mixed media structures as well as the structure-property relationships of the nonwoven fabric. Property and structure analysis will also take place on mixed media structures containing poly(lactic acid) as a sacrificial component in the bicomponent fiber after optimizing the removal conditions of the poly(lactic acid) in a sodium hydroxide (NaOH) bath.

  4. The Structural Properties of Sexual Fantasies for Sexual Offenders: A Preliminary Model

    Science.gov (United States)

    Gee, Dion; Ward, Tony; Belofastov, Aleksandra; Beech, Anthony

    2006-01-01

    While the phenomenon of sexual fantasy has been researched extensively, little contemporary inquiry has investigated the structural properties of sexual fantasy within the context of sexual offending. In this study, a qualitative analysis was used to develop a descriptive model of the phenomena of sexual fantasy during the offence process.…

  5. Structure-Property Relationships of Solid State Additive Manufactured Aluminum Alloy 2219 and Inconel 625

    Science.gov (United States)

    Rivera Almeyda, Oscar G.

    in the three directions and an average grain size of 2.5 microns. EBSD PFs showed that the material has a strong torsional fiber A texture in the top of the build, and this texture gets weaker in the middle and bottom sections. TEM showed that there are no theta' precipitates in the as-deposited cross-section, therefore no precipitation strengthening should be expected. Strain rate and stress state dependence was study, and in both tension and compression, with an increase in strain rate, the YS increase and the UTS decreased. Ductile fracture surface was observed on specimens tested to failure in both QS and HR. The AFS AA2219 processing-structure-property relations are being studied in this investigation to address the stress-state and strain rate dependence of AFS AA2219 with an internal sate variable (ISV) plasticity-damage model to capture the different yield stress, work hardening and failure strain in the AFS AA2219 for high fidelity modeling of AFS components. The ISV plasticity model successfully captured the material behavior in tension, compression, tension-followed-by-compression and compression-followed-by-tension experiments. Furthermore, the damage parameters of the model were calibrated using the final void density measured from the fracture surfaces.

  6. Process-Structure-Property Relationship in Magnesium-Based Biodegradable Alloy for Biomedical Applications

    Science.gov (United States)

    Trivedi, Pramanshu

    Magnesium alloys are considered to be the next generation of biomaterials because of their ability to degrade in the physiological environment. We elucidate here the impact of multiaxial forging of Mg-2Zn-2Gd alloy on grain refinement to sub-micron regime and relate the structure to mechanical properties and biological functionality. As-cast and annealed samples were multiaxial forged (MAF) for a total number of two passes with a true strain of 2/pass. Considering that the microstructure governs the biological response of materials, we studied the constituents of the microstructure in conjunction with the mechanical behavior. The antimicrobial behavior in a Mg-2Zn-2Gd alloy with different grain size in the range of 44 microm to 710 nm was studied by seeding. Surface energy and contact angle measurements using goniometer and wettability were assessed with water, SBF, n-Hexane, and DMEM. The structure-property relationship in Mg-2Zn-2Gd alloy to maintaining mechanical integrity during degradation was studied by seeding Escherichia coli ( E. coli). Furthermore, we studied the effect of degradation behavior in the presence and absence of cells. This was followed by the study of bioactivity in terms of phases present on the surface and degradation products in simulated body fluid (SBF). Magnesium coated with apatite using a biomimetic approach were placed in a 24-well culture plate with alpha-MEM media and the degradation behavior was studied in the absence and presence of cells (seeding density: 10,000 cells/cm2). The change in pH was monitored at regular intervals. Cell attachment was studied by seeding the cells for 4h and cell viability was studied by seeding the cells for up to 1, 3, and 7 days. The study underscores that the fine-grained alloys exhibited superior mechanical properties, antimicrobial resistance, and cell attachment. The degradation rate was also least for fine-grained alloy. The higher surface energy of ultrafine-grained Mg-2Zn-2Gd alloy led to the

  7. Quantitative description on structure-property relationships of Li-ion battery materials for high-throughput computations.

    Science.gov (United States)

    Wang, Youwei; Zhang, Wenqing; Chen, Lidong; Shi, Siqi; Liu, Jianjun

    2017-01-01

    Li-ion batteries are a key technology for addressing the global challenge of clean renewable energy and environment pollution. Their contemporary applications, for portable electronic devices, electric vehicles, and large-scale power grids, stimulate the development of high-performance battery materials with high energy density, high power, good safety, and long lifetime. High-throughput calculations provide a practical strategy to discover new battery materials and optimize currently known material performances. Most cathode materials screened by the previous high-throughput calculations cannot meet the requirement of practical applications because only capacity, voltage and volume change of bulk were considered. It is important to include more structure-property relationships, such as point defects, surface and interface, doping and metal-mixture and nanosize effects, in high-throughput calculations. In this review, we established quantitative description of structure-property relationships in Li-ion battery materials by the intrinsic bulk parameters, which can be applied in future high-throughput calculations to screen Li-ion battery materials. Based on these parameterized structure-property relationships, a possible high-throughput computational screening flow path is proposed to obtain high-performance battery materials.

  8. Determination of Basic Structure-Property Relations for Processing and Modeling in Advanced Nuclear Fuel: Microstructure Evolution and Mechanical Properties

    International Nuclear Information System (INIS)

    Wheeler, Kirk; Parra, Manuel; Peralta, Pedro

    2009-01-01

    The project objective is to study structure-property relations in solid solutions of nitrides and oxides with surrogate elements to simulate the behavior of fuels of inert matrix fuels of interest to the Advanced Fuel Cycle Initiative (AFCI), with emphasis in zirconium-based materials. Work with actual fuels will be carried out in parallel in collaboration with Los Alamos National Laboratory (LANL). Three key aspects will be explored: microstructure characterization through measurement of global texture evolution and local crystallographic variations using Electron Backscattering Diffraction (EBSD); determination of mechanical properties, including fracture toughness, quasi-static compression strength, and hardness, as functions of load and temperature, and, finally, development of structure-property relations to describe mechanical behavior of the fuels based on experimental data. Materials tested will be characterized to identify the mechanisms of deformation and fracture and their relationship to microstructure and its evolution. New aspects of this research are the inclusion of crystallographic information into the evaluation of fuel performance and the incorporation of statistical variations of microstructural variables into simplified models of mechanical behavior of fuels that account explicitly for these variations. The work is expected to provide insight into processing conditions leading to better fuel performance and structural reliability during manufacturing and service, as well as providing a simplified testing model for future fuel production

  9. Determination of Quantitative Structure-Property Relationships of Solvent Resistance of Polycarbonate Copolymers Using a Resonant Multisensor System

    Science.gov (United States)

    Potyrailo, Radislav A.; Wroczynski, Ronald J.; McCloskey, Patrick J.; Morris, William G.

    In sensor and microfluidic applications, the need is to have an adequate solvent resistance of polymers to prevent degradation of the substrate surface upon deposition of sensor formilations, to prevent contamination of the solvent-containing sensor formulations or contamination of organic liquid reactions in microfluidic channels. Unfortunately, no comprehensive quantitative reference solubility data of unstressed copolymers is available to date. In this study, we evaluate solvent-resistance of several polycarbonate copolymers prepared from the reaction of hydroquinone (HQ), resorcinol (RS), and bisphenol A (BPA). Our high-throughput polymer evaluation approach permitted the construction of detailed solvent-resistance maps, the development of quantitative structure-property relationships for BPA-HQ-RS copolymers and provided new knowledge for the further development of the polymeric sensor and microfluidic components.

  10. ProMT: effective human promoter prediction using Markov chain model based on DNA structural properties.

    Science.gov (United States)

    Xiong, Dapeng; Liu, Rongjie; Xiao, Fen; Gao, Xieping

    2014-12-01

    The core promoters play significant and extensive roles for the initiation and regulation of DNA transcription. The identification of core promoters is one of the most challenging problems yet. Due to the diverse nature of core promoters, the results obtained through existing computational approaches are not satisfactory. None of them considered the potential influence on performance of predictive approach resulted by the interference between neighboring TSSs in TSS clusters. In this paper, we sufficiently considered this main factor and proposed an approach to locate potential TSS clusters according to the correlation of regional profiles of DNA and TSS clusters. On this basis, we further presented a novel computational approach (ProMT) for promoter prediction using Markov chain model and predictive TSS clusters based on structural properties of DNA. Extensive experiments demonstrated that ProMT can significantly improve the predictive performance. Therefore, considering interference between neighboring TSSs is essential for a wider range of promoter prediction.

  11. A quantitative structure- property relationship of gas chromatographic/mass spectrometric retention data of 85 volatile organic compounds as air pollutant materials by multivariate methods

    Directory of Open Access Journals (Sweden)

    Sarkhosh Maryam

    2012-05-01

    Full Text Available Abstract A quantitative structure-property relationship (QSPR study is suggested for the prediction of retention times of volatile organic compounds. Various kinds of molecular descriptors were calculated to represent the molecular structure of compounds. Modeling of retention times of these compounds as a function of the theoretically derived descriptors was established by multiple linear regression (MLR and artificial neural network (ANN. The stepwise regression was used for the selection of the variables which gives the best-fitted models. After variable selection ANN, MLR methods were used with leave-one-out cross validation for building the regression models. The prediction results are in very good agreement with the experimental values. MLR as the linear regression method shows good ability in the prediction of the retention times of the prediction set. This provided a new and effective method for predicting the chromatography retention index for the volatile organic compounds.

  12. Meso-design of heterogeneous dielectric material systems: Structure property relationships

    Directory of Open Access Journals (Sweden)

    Jeffrey Baker

    2014-04-01

    Full Text Available Heterogeneous materials are inherently dielectric, and charge distribution and transport in such materials involves complex local fields and polarizations that are remarkably sensitive to morphology and the interaction of conduction and permittivity. Trial and error design of such material systems is time consuming and expensive, and often ineffectual. However, heterogeneous materials are essential for energy conversion and storage, and they have become the foundation for major advances in the performance of devices such as batteries, fuel cells, separation membranes, and solar cells. The present paper presents some relationships in support of rational design based on an extensive experimental validation of the concepts and analysis that form a foundation for that design. Salient results include the prediction and confirmation of volume fraction effects (including nondilute mixtures, and the prediction and direct measurement of surface charge effects at internal interfaces as a function of constituent morphology and orientation.

  13. S09 Symposium KK, Structure-Property Relationships in Biomineralized and Biomimetic Composites

    Energy Technology Data Exchange (ETDEWEB)

    David Kisailus; Lara Estroff; Himadri S. Gupta; William J. Landis; Pablo D. Zavattieri

    2010-06-07

    The technical presentations and discussions at this symposium disseminated and assessed current research and defined future directions in biomaterials research, with a focus on structure-function relationships in biological and biomimetic composites. The invited and contributed talks covered a diverse range of topics from fundamental biology, physics, chemistry, and materials science to potential applications in developing areas such as light-weight composites, multifunctional and smart materials, biomedical engineering, and nanoscaled sensors. The invited speakers were chosen to create a stimulating program with a mixture of established and junior faculty, industrial and academic researchers, and American and international experts in the field. This symposium served as an excellent introduction to the area for younger scientists (graduate students and post-doctoral researchers). Direct interactions between participants also helped to promote potential future collaborations involving multiple disciplines and institutions.

  14. Structure-property relationship in cytotoxicity and cell uptake of poly(2-oxazoline) amphiphiles

    KAUST Repository

    Luxenhofer, Robert

    2011-07-01

    The family of poly(2-oxazoline)s (POx) is being increasingly investigated in the context of biomedical applications. We tested the relative cytotoxicity of POx and were able to confirm that these polymers are typically not cytotoxic even at high concentrations. Furthermore, we report structure-uptake relationships of a series of amphiphilic POx block copolymers that have different architectures, molar mass and chain termini. The rate of endocytosis can be fine-tuned over a broad range by changing the polymer structure. The cellular uptake increases with the hydrophobic character of the polymers and is observed even at nanomolar concentrations. Considering the structural versatility of this class of polymers, the relative ease of preparation and their stability underlines the potential of POx as a promising platform candidate for the preparation of next-generation polymer therapeutics.

  15. An Overview of the Structure-Property Relationships in Silicon-Based Oxynitride Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Becher, Paul F [ORNL; Hampshire, Stuart [University of Limerick; Pomeroy, Michael [University of Limerick; Hoffmann, M. J. [Universituet Karlsruhe, Germany; Lance, Michael J [ORNL; Satet, Raphaella L. [Universituet Karlsruhe, Germany

    2011-01-01

    The silicon oxynitride glasses take advantage of nitrogen-bonding to attain high elastic modulus, increased softening temperatures and viscosities, greater slow crack growth resistance and modest gains in fracture resistance. Of the oxynitride glasses, the Si-Y-Al based oxynitride glasses have been most extensively studied and a degree of success has been achieved in understanding how changes in glass composition affect structural parameters and their relationship to properties. More recent studies have focused on the Si-RE-Me oxynitride glasses where Me is primarily Al or Mg and RE includes most of the lanthanide series elements. These glasses possess a range of elastic, thermal, mechanical and optical properties, which can be correlated with the strength of the RE bond in terms of the cationic field strength. However, such correlation require knowledge of not only the RE valence state but also its coordination with the anions. Herein, the current state of the art understanding of the properties and structural parameters of oxynitride glasses and their interrelationships are reviewed.

  16. FOOD PROCESSING TECHNOLOGY AS A MEDIATOR OF FUNCTIONALITY. STRUCTURE-PROPERTY-PROCESS RELATIONSHIPS

    Directory of Open Access Journals (Sweden)

    Ester Betoret

    2015-02-01

    Full Text Available During the last years, the food industry has been facing technical and economic changes both in society and in the food processing practices, paying high attention to food products that meet the consumers´ demands. In this direction, the study areas in food process and products have evolved mainly from safety to other topics such as quality, environment or health. The improvement of the food products is now directed towards ensuring nutritional and specific functional benefits. Regarding the processes evolution, they are directed to ensure the quality and safety of environmentally friendly food products produced optimizing the use of resources, minimally affecting or even enhancing their nutritional and beneficial characteristics. The product structure both in its raw form and after processing plays an important role maintaining, enhancing and delivering the bioactive compounds in the appropriate target within the organism. The aim of this review is to make an overview on some synergistic technologies that can constitute a technological process to develop functional foods, enhancing the technological and/or nutritional functionality of the food products in which they are applied. More concretely, the effect of homogenization, vacuum impregnation and drying operations on bioactive compounds have been reviewed, focusing on the structure changes produced and its relationship on the product functionality, as well as on the parameters and the strategies used to quantify and increase the achieved functionality.

  17. A study of structure-property relationships in layered copper oxides

    CERN Document Server

    Hyatt, N

    2000-01-01

    described in Chapter Five. This investigation demonstrates that several intimate structure-compressibility relationships exist in these materials. Chapter Six continues the theme of high pressure crystallography, and examines, in detail, the crystal structure of HgBa sub 2 CuO sub 4 sub + subdelta using high pressure neutron diffraction methods. This study indicates that the pressure induced increase in T sub c observed in HgBa sub 2 CuO sub 4 sub + subdelta, may be related to pressure induced relief of structural strain at the interface between the rock-salt and perovskite type layers of this material. Chapter Seven examines the crystal structure of Hg sub 0 sub . sub 8 Cr sub 0 sub . sub 2 Ba sub 2 CuO sub 4 sub + subdelta under ambient and applied pressure. This study shows that significant distortions arise in the crystal structure of HgBa sub 2 CuO sub 4 sub + subdelta when linear HgO sub 2 units are substituted by tetrahedral CrO sub 4 units. Finally, Chapter Eight describes a simple method for the fabr...

  18. Composition - structure - properties relationships of peraluminous glasses for nuclear waste containment

    International Nuclear Information System (INIS)

    Piovesan, Victor

    2016-01-01

    Part of the Research and Development program concerning high level nuclear waste conditioning aims to assess new glass formulations able to incorporate a high waste content with enhanced properties in terms of homogeneity, thermal stability, long term behavior and process ability. This study focuses on peraluminous glasses, defined by an excess of aluminum ions Al 3+ in comparison with modifier elements such as Na + , Li + or Ca 2+ . A Design of Experiment approach has been employed to determine relationships between composition of simplified peraluminous glasses (SiO 2 - B 2 O 3 - Al 2 O 3 - Na 2 O - Li 2 O - CaO - La 2 O 3 ) and their physical properties such as viscosity, glass transition temperature and glass homogeneity. Moreover, some structural investigation (NMR) was performed in order to better understand the structural role of Na + , Li + and Ca 2+ and the structural organization of peraluminous glasses. Then, physical and chemical properties of fully simulated peraluminous glasses were characterized to evaluate transposition between simplified and fully simulated glasses and also to put forward the potential of peraluminous glasses for nuclear waste containment. (author) [fr

  19. Structure - Property Relationships of Furanyl Thermosetting Polymer Materials Derived from Biobased Feedstocks

    Science.gov (United States)

    Hu, Fengshuo

    Biobased thermosetting polymers have drawn significant attention due to their potential positive economic and ecological impacts. New materials should mimic the rigid, phenylic structures of incumbent petroleum-based thermosetting monomers and possess superior thermal and mechanical properties. Furans and triglycerides derived from cellulose, hemicellulose and plant oils are promising candidates for preparing such thermosetting materials. In this work, furanyl diepoxies, diamines and di-vinyl esters were synthesized using biobased furanyl materials, and their thermal and mechanical properties were investigated using multiple techniques. The structure versus property relationship showed that, compared with the prepared phenylic analogues, biobased furanyl thermosetting materials possess improved glassy storage modulus (E '), advanced fracture toughness, superior high-temperature char yield and comparable glass transition temperature (Tg) properties. An additive molar function analysis of the furanyl building block to the physical properties, such as Tg and density, of thermosetting polymers was performed. The molar glass transition function value (Yg) and molar volume increment value (Va,i) of the furanyl building block were obtained. Biobased epoxidized soybean oil (ESO) was modified using different fatty acids at varying molar ratios, and these prepared materials dramatically improved the critical strain energy release rate (G1c) and the critical stress intensity factor (K1c) values of commercial phenylic epoxy resins, without impairing their Tg and E ' properties. Overall, it was demonstrated that biobased furans and triglycerides possess promising potential for use in preparing high-performance thermosetting materials, and the established methodologies in this work can be utilized to direct the preparation of thermosetting materials with thermal and mechanical properties desired for practical applications.

  20. Structure-Property Relationships in Polymer Derived Amorphous/Nano-Crystalline Silicon Carbide for Nuclear Applications

    International Nuclear Information System (INIS)

    Zunjarrao, Suraj C.; Singh, Abhishek K.; Singh, Raman P.

    2006-01-01

    difficulties in interpreting 'true' properties from bulk measurements. Hence, hardness and modulus measurements are carried out using instrumented nano-indentation to establish property--structure relationship for SiC derived from the polymer precursor. It is seen that the presence of nanocrystalline domains in amorphous SiC significantly influences the modulus and hardness. (authors)

  1. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    In the present study, on the basis of detailed density functional theory (DFT) calculations, and using Ni hydroxy(oxide) films on Pt(111) and Au(111) electrodes as model systems, we describe a detailed structural and electrocatalytic analysis of hydrogen evolution (HER) at three-phase boundaries...... of information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  2. Kinetic Control of Aqueous Hydrolysis: Modulating Structure/Property Relationships in Inorganic Crystals

    Science.gov (United States)

    Neilson, James R.

    2011-12-01

    A grand challenge in materials science and chemistry revolves around the preparation of materials with desired properties by controlling structure on multiple length scales. Biology approaches this challenge by evolving tactics to transform soluble precursors into materials and composites with macro-scale and atomic precision. Studies of biomineralization in siliceous sponges led to the discovery of slow, catalytic hydrolysis of molecular precursors in the biogenesis of silica skeletal elements with well defined micro- and nano-scale architectures. However, the role of aqueous hydrolysis in the limit of kinetic control is not well understood; this allows us to form a central hypothesis: that the kinetics of hydrolysis modulate the structures of materials and their properties. As a model system, the diffusion of a simple hydrolytic catalyst (such as ammonia) across an air-water interface into a metal salt solution reproduces some aspects of the chemistry found in biomineralization, namely kinetic and vectorial control. Variation of the catalyst concentration modulates the hydrolysis rate, and thus alters the resulting structure of the inorganic crystals. Using aqueous solutions of cobalt(II) chloride, each product (cobalt hydroxide chloride) forms with a unique composition, despite being prepared from identical mother liquors. Synchrotron X-ray total scattering methods are needed to locate the atomic positions in the material, which are not aptly described by a traditional crystallographic unit cell due to structural disorder. Detailed definition of the structure confirms that the hydrolysis conditions systematically modulate the arrangement of atoms in the lattice. This tightly coupled control of crystal formation and knowledge of local and average structures of these materials provides insight into the unusual magnetic properties of these cobalt hydroxides. The compounds studied show significant and open magnetization loops with little variation with composition

  3. Low-Dimensional Material: Structure-Property Relationship and Applications in Energy and Environmental Engineering

    Science.gov (United States)

    Xiao, Hang

    In the past several decades, low-dimensional materials (0D materials, 1D materials and 2D materials) have attracted much interest from both the experimental and theoretical points of view. Because of the quantum confinement effect, low-dimensional materials have exhibited a kaleidoscope of fascinating phenomena and unusual physical and chemical properties, shedding light on many novel applications. Despite the enormous success has been achieved in the research of low-dimensional materials, there are three fundamental challenges of research in low-dimensional materials: 1) Develop new computational tools to accurately describe the properties of low-dimensional materials with low computational cost. 2) Predict and synthesize new low-dimensional materials with novel properties. 3) Reveal new phenomenon induced by the interaction between low-dimensional materials and the surrounding environment. In this thesis, atomistic modelling tools have been applied to address these challenges. We first developed ReaxFF parameters for phosphorus and hydrogen to give an accurate description of the chemical and mechanical properties of pristine and defected black phosphorene. ReaxFF for P/H is transferable to a wide range of phosphorus and hydrogen containing systems including bulk black phosphorus, blue phosphorene, edge-hydrogenated phosphorene, phosphorus clusters and phosphorus hydride molecules. The potential parameters were obtained by conducting global optimization with respect to a set of reference data generated by extensive ab initio calculations. We extended ReaxFF by adding a 60° correction term which significantly improved the description of phosphorus clusters. Emphasis was placed on the mechanical response of black phosphorene with different types of defects. Compared to the nonreactive SW potential of phosphorene, ReaxFF for P/H systems provides a significant improvement in describing the mechanical properties of the pristine and defected black phosphorene, as well

  4. Structure-property relationships in novel polymers and block copolymers from ring-opening metathesis polymerization

    Science.gov (United States)

    Bishop, John Paul

    2011-12-01

    crystallites, limiting their lateral growth and generating composite hard domains with both crystalline and glassy components. The pentablocks show the low initial modulus, strain-hardening behavior, and small permanent set desired for TPEs, while retaining an easily-processed single-phase melt. We found that the chain microstructure (cis/trans ratio) in the ROMP of norbornene and methyltetracyclododecene (MTD) using a so-called Schrock-type initiator to be a strong function of monomer concentration, providing a convenient means for tuning the average trans content in the resulting polymers. The results are explained based on a literature kinetic description for the behavior of this initiator, which allowed for the development of a quantitative model to describe the observed experimental data. In contrast, ROMP of MTD using the first-generation Grubbs initiator showed no dependence of the trans content on monomer concentration. hPN is unusual in that it is highly crystalline despite having an atactic placement of its backbone cyclopentylene rings. Furthermore, it has a crystal-crystal transition at elevated temperatures (˜110°C) where the crystal structure transforms from a conventional, three-dimensionally-ordered monoclinic lattice at lower temperatures to a high-temperature crystal polymorph that is rotationally disordered and shows a pseudo-hexagonal packing transverse to the chain axes. The tacticity of hPN, measured to first order as the ratio of meso to racemo dyads (m:r), was varied by altering the synthesis conditions, and was shown to have a direct correlation with the temperature at which the crystal-crystal transition occurs (T cc). Small changes in m:r (from 0.8 to 1.1) are sufficient to raise Tcc by nearly 20°C. When heated above Tcc, hPN crystals thicken at a rate much greater than conventional three-dimensionally-ordered crystals, but below the rates shown by the two-dimensional hexagonal (columnar) phase formed by some polymers. Finally, we report the

  5. Effect of conditioners upon the thermodynamics and kinetics of methane hydrate formation. A preliminary structure-properties relationship study

    Energy Technology Data Exchange (ETDEWEB)

    Di Profio, Pietro; Arca, Simone; Germani, Raimondo; Savelli, Gianfranco

    2005-07-01

    The synthesis and stability of gas hydrates was found to be heavily affected by the presence of small quantities of additives, or conditioners, particularly surfactants. In a recent work, we showed that the enhancement of hydrate formation, both from previously described and newly synthesized surfactants, is probably due to surfactant monomers, rather than micelles, and that the features of hydrate induction time should not be used as a measure of critical micelle concentration. In the present paper, we discuss the results of a structure-properties relationship study in which a preliminary attempt to relate the structural features of several amphiphilic additives to some kinetic and thermodynamic parameters of methane hydrate formation - e.g., induction times, rate of formation, occupancy, etc. - is conducted. According to the present study, it is found that, for a particular conditioner, a reduction of induction time does not correlate to an increase of the formation rate and occupancy, and vice versa. This may be related to the nature of chemical moieties forming a particular amphiphile (e.g., the hydrophobic tail, head group, counterion, etc.). The understanding of the mechanisms by which those moieties play their differential role may be the key tool to the design and synthesis of tailored conditioners. (Author)

  6. Structure-property-processing relationships and the effects of physical structure on the hygrothermal durability and mechanical response of polyimides

    Science.gov (United States)

    Lincoln, Jason E.

    Structure-property-processing interrelationships ate characterized for a variety of polyimide composite matrices used in advanced aerospace structural applications. The relationships between chemical/physical structure and (i) fabrication conditions, (ii) mechanical, thermal, and physical properties, and (iii) hydrolytic stability, are investigated. Major findings determined from this research are presented below. Carbon fiber/bismaleimide (BMI) cross-ply composite laminates are microcracked after standard cure and postcure procedures. Using a unique in-situ characterization of microcracking, it is demonstrated that extended cure times at low temperatures (177°C) prior to postcure can shift the microcracking threshold in these composites. Ultimately cute induced microcracking can be prevented under standard fabrication postcure temperatures as a result of a reduction in composite residual stress and an improved fiber/matrix interphase. Structure-property-processing characterization of BMI, polyetherimide (PEI), poly(4,4'-oxydiphenylene pyromellitimide) (POPPI), and a phenylethynyl terminated imide oligomer (PETI-5) demonstrates that deformation in thermoplastic polyimides is controlled primarily by free volume. In thermosets, deformation is controlled by network defects and free volume. Interestingly, PETI-5 was shown to crystallize under certain time-temperature cure cycles, which results in dramatic changes in neat resin mechanical properties. The observed crystallization behavior appears to be a result of liquid crystal-like ordering due to the phenylethynyl end groups. With respect to hygrothermal durability, thermoset polyimides prove to be more resistant to blistering and associated macroscopic damage than thermoplastics under hygrothermal excursions unless hydrolytic degradation induced chain scission has occurred. Accelerated hygrothermal exposure also demonstrated that the hydrolytic stability of polyimides is strongly dependent on the chemical nature of

  7. A model study on color and related structural properties of cured porcine batters

    NARCIS (Netherlands)

    Palombo, R.

    1990-01-01

    Color, determined by tristimulus colorimeters, and related structural properties, i.e., microstructure, surface rheology, and bulk rheology, of cured porcine meat batters were studied.

    Effects of various processing factors (such as, temperature, air pressure during chopping, and

  8. Water solubility of selected C9-C18 alkanes using a slow-stir technique: Comparison to structure - property models.

    Science.gov (United States)

    Letinski, Daniel J; Parkerton, Thomas F; Redman, Aaron D; Connelly, Martin J; Peterson, Brian

    2016-05-01

    Aqueous solubility is a fundamental physical-chemical substance property that strongly influences the distribution, fate and effects of chemicals upon release into the environment. Experimental water solubility was determined for 18 selected C9-C18 normal, branched and cyclic alkanes. A slow-stir technique was applied to obviate emulsion formation, which historically has resulted in significant overestimation of the aqueous solubility of such hydrophobic liquid compounds. Sensitive GC-MS based methods coupled with contemporary sample extraction techniques were employed to enable reproducible analysis of low parts-per billion aqueous concentrations. Water solubility measurements for most of the compounds investigated, are reported for the first time expanding available data for branched and cyclic alkanes. Measured water solubilities spanned four orders of magnitude ranging from 0.3 μg/L to 250 μg/L. Good agreement was observed for selected alkanes tested in this work and reported in earlier literature demonstrating the robustness of the slow-stir water solubility technique. Comparisons of measured alkane water solubilities were also made with those predicted by commonly used quantitative structure-property relationship models (e.g. SPARC, EPIWIN, ACD/Labs). Correlations are also presented between alkane measured water solubilities and molecular size parameters (e.g. molar volume, solvent accessible molar volume) affirming a mechanistic description of empirical aqueous solubility results and prediction previously reported for a more limited set of alkanes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Land-use and land-management change: relationships with earthworm and fungi communities and soil structural properties.

    Science.gov (United States)

    Spurgeon, David J; Keith, Aidan M; Schmidt, Olaf; Lammertsma, Dennis R; Faber, Jack H

    2013-12-01

    Change in land use and management can impact massively on soil ecosystems. Ecosystem engineers and other functional biodiversity in soils can be influenced directly by such change and this in turn can affect key soil functions. Here, we employ meta-analysis to provide a quantitative assessment of the effects of changes in land use and land management across a range of successional/extensification transitions (conventional arable → no or reduced tillage → grassland → wooded land) on community metrics for two functionally important soil taxa, earthworms and fungi. An analysis of the relationships between community change and soil structural properties was also included. Meta-analysis highlighted a consistent trend of increased earthworm and fungal community abundances and complexity following transitions to lower intensity and later successional land uses. The greatest changes were seen for early stage transitions, such as introduction of reduced tillage regimes and conversion to grassland from arable land. Not all changes, however, result in positive effects on the assessed community metrics. For example, whether woodland conversion positively or negatively affects community size and complexity depends on woodland type and, potentially, the changes in soil properties, such as pH, that may occur during conversion. Alterations in soil communities tended to facilitate subsequent changes in soil structure and hydrology. For example, increasing earthworm abundances and functional group composition were shown to be positively correlated with water infiltration rate (dependent on tillage regime and habitat characteristics); while positive changes in fungal biomass measures were positively associated with soil microaggregate stability. These findings raise the potential to manage landscapes to increase ecosystem service provision from soil biota in relation to regulation of soil structure and water flow.

  10. Selective extraction of americium(III) over europium(III) ions with pyridylpyrazole ligands. Structure-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Su, Dongping; Liu, Ying; Li, Shimeng; Ding, Songdong; Jin, Yongdong; Wang, Zhipeng; Hu, Xiaoyang; Zhang, Lirong [Department of chemistry, Sichuan University, Chengdu (China)

    2017-01-18

    To clarify the structure-property relationships of pyridylpyrazole ligands and provide guidance for the design of new and more efficient ligands for the selective extraction of actinides over lanthanides, a series of alkyl-substituted pyridylpyrazole ligands with different branched chains at different positions of the pyrazole ring were synthesized. Extraction experiments showed that the pyridylpyrazole ligands exhibited good selective extraction abilities for Am{sup III} ions, and the steric effects of the branched chain had a significant impact on the distribution ratios of Am{sup III} and Eu{sup III} ions as well as the separation factor. Moreover, both slope analyses and UV/Vis spectrometry titrations indicated the formation of a 1:1 complex of 2-(1-octyl-1H-pyrazol-3-yl)pyridine (C8-PypzH) with Eu{sup III} ions. The stability constant (log K) for this complex obtained from the UV/Vis titration was 4.45 ± 0.04. Single crystals of the complexes of 3-(2-pyridyl)pyrazole (PypzH) with Eu(NO{sub 3}){sub 3} and Sm(NO{sub 3}){sub 3} were obtained; PypzH acts as a bidentate ligand in the crystal structures, and the N atom with a bound H atom did not participate in the coordination. In general, this study revealed some interesting findings on the effects of the alkyl-chain structure and the special complexation between pyridylpyrazole ligands and Ln{sup III} ions. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Random blebbing motion: A simple model linking cell structural properties to migration characteristics

    Science.gov (United States)

    Woolley, Thomas E.; Gaffney, Eamonn A.; Goriely, Alain

    2017-07-01

    If the plasma membrane of a cell is able to delaminate locally from its actin cortex, a cellular bleb can be produced. Blebs are pressure-driven protrusions, which are noteworthy for their ability to produce cellular motion. Starting from a general continuum mechanics description, we restrict ourselves to considering cell and bleb shapes that maintain approximately spherical forms. From this assumption, we obtain a tractable algebraic system for bleb formation. By including cell-substrate adhesions, we can model blebbing cell motility. Further, by considering mechanically isolated blebbing events, which are randomly distributed over the cell, we can derive equations linking the macroscopic migration characteristics to the microscopic structural parameters of the cell. This multiscale modeling framework is then used to provide parameter estimates, which are in agreement with current experimental data. In summary, the construction of the mathematical model provides testable relationships between the bleb size and cell motility.

  12. High-throughput determination of quantitative structure-property relationships using a resonant multisensor system: solvent resistance of bisphenol a polycarbonate copolymers.

    Science.gov (United States)

    Potyrailo, Radislav A; McCloskey, Patrick J; Wroczynski, Ronald J; Morris, William G

    2006-05-01

    Polymers are important materials for sensor, microfluidic, and other demanding applications. High-throughput screening methodology has been applied for the evaluation of the solvent resistance of a family of polycarbonate copolymers prepared from the reaction of bisphenol A (BPA), hydroquinone (HQ), and resorcinol (RS) in different solvents of practical importance, such as chloroform, tetrahydrofuran (THF), and methyl ethyl ketone (MEK). We employed a 24-channel acoustic-wave sensor system that provided previously unavailable capabilities for parallel evaluation of polymer solvent resistance. This high-throughput polymer evaluation approach assisted in construction of detailed solvent-resistance maps of polycarbonate copolymers and in determination of quantitative structure-property relationships. The best absolute solvent resistance of all studied copolymers was achieved in MEK, followed by chloroform and THF. A D-optimal mixture design was employed to explore the relationship between the copolymer compositions and their solvent resistance. The applied special cubic model for each solvent took into account the primary mixture terms such as BPA, HQ, and RS; binary interaction terms such as BPA-HQ, BPA-RS, and HQ-RS; and a ternary interaction term BPA-HQ-RS. A combination of the normal distribution of the model residuals and the very high values of adjusted R2 (0.97-0.99) demonstrated a good quality of the model. At a HQ concentration of 40 mol %, the solvent resistance was the highest for all tested solvents, and different concentrations of BPA (40 and 60 mol %) and RS (0 and 20 mol %) did not affect the solvent resistance. Without HQ, solvent resistance was decreasing with an increase of RS and decrease of BPA. Overall, with an increase of HQ concentration from 0 to 40 mol %, the solvent resistance of BPA-HQ-RS copolymers was improved by up to 3 times in THF, by 21 times in chloroform, and by 32 times in MEK.

  13. From Structural Complexity to Structure-Property Relationships in Intermetallics: Development of Density Functional Theory-Chemical Pressure Analysis

    Science.gov (United States)

    Engelkemier, Joshua

    away from each other (negative CP). This technique is used in combination with the concept of structural plasticity (Berns, 2014) to demonstrate how complex intermetallic phases can be understood as a response of simpler structure types to the destabilizing buildup of CP. From this point of view, interfaces created in complex structures relieve the CP manifest in the more basic, parent structures. This is shown specifically for Ca36Sn23 relative to a hypothetical W5Si3-type Ca5Sn3 phase, LnMn xGa3 (Ln = Ho-Tm, x < 0.15) compared to unstuffed AuCu3-type LnGa3 structures, and structural derivatives of CaCu5- and HoCoGa5-type compounds. As a direct result of the technical developments necessitated by these analyses on structural complexity in intermetallics, a further connection is made in this thesis between the calculated CP schemes and the frequencies of vibrational modes in MgCu2-type CaPd2, the Cr 3Si-type superconductor Nb3Ge, and CaCu5-type CaPd5. Local chemical interactions revealed by DFT-CP analysis are used to identify structure-property relationships for the pseudogap in the phonon density of states (DOS) of CaPd2, the higher critical temperature of Nb3Ge vs. Nb3Sn, and the wide diversity of structures based on the CaCu5 type.

  14. 2D Quantitative Structure-Property Relationship Study of Mycotoxins by Multiple Linear Regression and Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Fereshteh Shiri

    2010-08-01

    Full Text Available In the present work, support vector machines (SVMs and multiple linear regression (MLR techniques were used for quantitative structure–property relationship (QSPR studies of retention time (tR in standardized liquid chromatography–UV–mass spectrometry of 67 mycotoxins (aflatoxins, trichothecenes, roquefortines and ochratoxins based on molecular descriptors calculated from the optimized 3D structures. By applying missing value, zero and multicollinearity tests with a cutoff value of 0.95, and genetic algorithm method of variable selection, the most relevant descriptors were selected to build QSPR models. MLRand SVMs methods were employed to build QSPR models. The robustness of the QSPR models was characterized by the statistical validation and applicability domain (AD. The prediction results from the MLR and SVM models are in good agreement with the experimental values. The correlation and predictability measure by r2 and q2 are 0.931 and 0.932, repectively, for SVM and 0.923 and 0.915, respectively, for MLR. The applicability domain of the model was investigated using William’s plot. The effects of different descriptors on the retention times are described.

  15. Investigation of the composition-structure-property relationship of AsxTe100 - x films prepared by plasma deposition

    Science.gov (United States)

    Mochalov, Leonid; Dorosz, Dominik; Nezhdanov, Aleksey; Kudryashov, Mikhail; Zelentsov, Sergey; Usanov, Dmitry; Logunov, Alexandr; Mashin, Aleksandr; Gogova, Daniela

    2018-02-01

    AsxTe100 - x amorphous films of different chemical content were prepared by Plasma-Enhanced Chemical Vapor Deposition (PECVD). For the first time the optical properties of As-Te chalcogenide materials have been measured in UV-VIS-IR ranges (from 0.2 to 25 μm) for a very wide range of chemical compositions (20-80 at.% As). As-Te films have been tuned from 0.80 to 1.10 eV. The IR results obtained have been juxtaposed with the Raman spectroscopy findings to establish the correlation between optical and structural properties of the materials developed. Reversible and irreversible changes in the phase composition of the As-Te films under annealing of the surface by laser irradiation have been demonstrated and studied. In order to determine the potential areas of application of the prepared As-Te films the thermal and photo sensitivity has been also investigated.

  16. Fluorescent J-aggregates of core-substituted perylene bisimides: studies on structure-property relationship, nucleation-elongation mechanism, and sergeants-and-soldiers principle.

    Science.gov (United States)

    Kaiser, Theo E; Stepanenko, Vladimir; Würthner, Frank

    2009-05-20

    A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a-e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength ("melting" temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure-property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation-elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K(2) = 13 +/- 11 L mol(-1) and for elongation of K = 2.3 +/- 0.1 x 10(6) L mol(-1) in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).

  17. Study on the structure-properties relationship of natural rubber/SiO2 composites modified by a novel multi-functional rubber agent

    Directory of Open Access Journals (Sweden)

    S. Y. Yang

    2014-06-01

    Full Text Available Vulcanization property and structure-properties relationship of natural rubber (NR/silica (SiO2 composites modified by a novel multi-functional rubber agent, N-phenyl- N'-(γ-triethoxysilane-propyl thiourea (STU, are investigated in detail. Results from the infrared spectroscopy (IR and X-ray photoelectron spectroscopy (XPS show that STU can graft to the surface of SiO2 under heating, resulting in a fine-dispersed structure in the rubber matrix without the connectivity of SiO2 particles as revealed by transmission electron microscopy (TEM. This modification effect reduces the block vulcanization effect of SiO2 for NR/SiO2/STU compounds under vulcanization process evidently. The 400% modulus and tensile strength of NR/SiO2/STU composites are much higher than that of NR/SiO2/TU composites, although the crystal index at the stretching ratio of 4 and crosslinking densities of NR/SiO2 composites are almost the same at the same dosage of SiO2. Consequently, a structure-property relationship of NR/SiO2/STU composites is proposed that the silane chain of STU can entangle with NR molecular chains to form an interfacial region, which is in accordance with the experimental observations quite well.

  18. Simulating Cellulose Structure, Properties, Thermodynamics, Synthesis, and Deconstruction with Atomistic and Coarse-Grain Models

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, M. F.; Matthews, J.; Beckham, G.; Bomble, Y.; Hynninen, A. P.; Ciesielski, P. F.

    2012-01-01

    Cellulose is still a mysterious polymer in many ways: structure of microfibrils, thermodynamics of synthesis and degradation, and interactions with other plant cell wall components. Our aim is to uncover the details and mechanisms of cellulose digestion and synthesis. We report the details of the structure of cellulose 1-beta under several temperature conditions and report here the results of these studies and connections to experimental measurements and the measurement in-silico the free energy of decrystallization of several morphologies of cellulose. In spatially large modeling, we show the most recent work of mapping atomistic and coarse-grain models into tomographic images of cellulose and extreme coarse-grain modeling of interactions of large cellulase complexes with microfibrils. We discuss the difficulties of modeling cellulose and suggest future work both experimental and theoretical to increase our understanding of cellulose and our ability to use it as a raw material for fuels and materials.

  19. Introducing improved structural properties and salt dependence into a coarse-grained model of DNA

    International Nuclear Information System (INIS)

    Snodin, Benedict E. K.; Mosayebi, Majid; Schreck, John S.; Romano, Flavio; Doye, Jonathan P. K.; Randisi, Ferdinando; Šulc, Petr; Ouldridge, Thomas E.; Tsukanov, Roman; Nir, Eyal; Louis, Ard A.

    2015-01-01

    We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na + ] = 0.5M), so that it can be used for a range of salt concentrations including those corresponding to physiological conditions. Finally, we use new experimental data to parameterise the oxDNA potential so that consecutive adenine bases stack with a different strength to consecutive thymine bases, a feature which allows a more accurate treatment of systems where the flexibility of single-stranded regions is important. We illustrate the new possibilities opened up by the updated model, oxDNA2, by presenting results from simulations of the structure of large DNA objects and by using the model to investigate some salt-dependent properties of DNA

  20. Introducing improved structural properties and salt dependence into a coarse-grained model of DNA

    Energy Technology Data Exchange (ETDEWEB)

    Snodin, Benedict E. K., E-mail: benedict.snodin@chem.ox.ac.uk; Mosayebi, Majid; Schreck, John S.; Romano, Flavio; Doye, Jonathan P. K., E-mail: jonathan.doye@chem.ox.ac.uk [Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom); Randisi, Ferdinando [Life Sciences Interface Doctoral Training Center, South Parks Road, Oxford OX1 3QU (United Kingdom); Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom); Šulc, Petr [Center for Studies in Physics and Biology, The Rockefeller University, 1230 York Avenue, New York, New York 10065 (United States); Ouldridge, Thomas E. [Department of Mathematics, Imperial College, 180 Queen’s Gate, London SW7 2AZ (United Kingdom); Tsukanov, Roman; Nir, Eyal [Department of Chemistry and the Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva (Israel); Louis, Ard A. [Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP (United Kingdom)

    2015-06-21

    We introduce an extended version of oxDNA, a coarse-grained model of deoxyribonucleic acid (DNA) designed to capture the thermodynamic, structural, and mechanical properties of single- and double-stranded DNA. By including explicit major and minor grooves and by slightly modifying the coaxial stacking and backbone-backbone interactions, we improve the ability of the model to treat large (kilobase-pair) structures, such as DNA origami, which are sensitive to these geometric features. Further, we extend the model, which was previously parameterised to just one salt concentration ([Na{sup +}] = 0.5M), so that it can be used for a range of salt concentrations including those corresponding to physiological conditions. Finally, we use new experimental data to parameterise the oxDNA potential so that consecutive adenine bases stack with a different strength to consecutive thymine bases, a feature which allows a more accurate treatment of systems where the flexibility of single-stranded regions is important. We illustrate the new possibilities opened up by the updated model, oxDNA2, by presenting results from simulations of the structure of large DNA objects and by using the model to investigate some salt-dependent properties of DNA.

  1. Innovative Technological Materials Structural Properties by Neutron Scattering, Synchrotron Radiation and Modeling

    CERN Document Server

    Skrzypek, Jacek J

    2010-01-01

    This book provides at first ideas on the answers that neutrons and Synchrotron Radiation could give in innovative materials science and technology. In particular, non-conventional, unusual or innovative neutron and x-ray scattering experiments (from both the scientific and the instrumental point of view) will be described which either have novel applications or provide a new insight into material science and technology. Moreover, a capability of the existing and the enhanced constitutive models and numerical procedures to predict complex behaviour of the novel multifunctional materials is examined.

  2. Innovative technological materials. Structural properties by neutron scattering, synchrotron radiation and modeling

    International Nuclear Information System (INIS)

    Rustichelli, Franco; Skrzypek, Jacek J.

    2010-01-01

    This book provides at first ideas on the answers that neutrons and Synchrotron Radiation could give in innovative materials science and technology. In particular, non-conventional, unusual or innovative neutron and X-ray scattering experiments (from both the scientific and the instrumental point of view) are described which either have novel applications or provide a new insight into material science and technology. Moreover, a capability of the existing and the enhanced constitutive models and numerical procedures to predict complex behaviour of the novel multifunctional materials is examined. (orig.)

  3. Molecular modeling studies of structural properties of polyvinyl alcohol: a comparative study using INTERFACE force field.

    Science.gov (United States)

    Radosinski, Lukasz; Labus, Karolina

    2017-10-05

    Polyvinyl alcohol (PVA) is a material with a variety of applications in separation, biotechnology, and biomedicine. Using combined Monte Carlo and molecular dynamics techniques, we present an extensive comparative study of second- and third-generation force fields Universal, COMPASS, COMPASS II, PCFF, and the newly developed INTERFACE, as applied to this system. In particular, we show that an INTERFACE force field provides a possibility of composing a reliable atomistic model to reproduce density change of PVA matrix in a narrow temperature range (298-348 K) and calculate a thermal expansion coefficient with reasonable accuracy. Thus, the INTERFACE force field may be used to predict mechanical properties of the PVA system, being a scaffold for hydrogels, with much greater accuracy than latter approaches. Graphical abstract Molecular Dynamics and Monte Carlo studies indicate that it is possible to predict properties of the PVA in narrow temperature range by using the INTERFACE force field.

  4. Weak temperature dependence of ageing of structural properties in atomistic model glassformers

    Science.gov (United States)

    Jenkinson, Thomas; Crowther, Peter; Turci, Francesco; Royall, C. Patrick

    2017-08-01

    Ageing phenomena are investigated from a structural perspective in two binary Lennard-Jones glassformers, the Kob-Andersen and Wahnström mixtures. In both, the geometric motif assumed by the glassformer upon supercooling, the locally favoured structure (LFS), has been established. The Kob-Andersen mixture forms bicapped square antiprisms; the Wahnström model forms icosahedra. Upon ageing, we find that the structural relaxation time has a time-dependence consistent with a power law. However, the LFS population and potential energy increase and decrease, respectively, in a logarithmic fashion. Remarkably, over the time scales investigated, which correspond to a factor of 104 change in relaxation times, the rate at which these quantities age appears almost independent of temperature. Only at temperatures far below the Vogel-Fulcher-Tamman temperature do the ageing dynamics slow.

  5. Research on the relationship between the structural properties of bedding layer in spring mattress and sleep quality.

    Science.gov (United States)

    Shen, Liming; Chen, Yu-xia; Guo, Yong; Zhong, ShiLu; Fang, Fei; Zhao, Jing; Hu, Tian-Yi

    2012-01-01

    Mattress, as a sleep platform, its types and physical properties has an important effect on sleep quality and rest efficiency. In this paper, by subjective evaluations, analysis of sleeping behaviors and tests of depth of sleep, the relationship between characteristics of the bedding materials, the structure of mattress, sleep quality and sleep behaviors were studied. The results showed that: (1) Characteristics of the bedding materials and structure of spring mattress had a remarkable effect on sleep behaviors and sleep quality. An optimum combination of the bedding materials, the structure of mattress and its core could improve the overall comfort of mattress, thereby improving the depth of sleep and sleep quality. (2) Sleep behaviors had a close relationship with sleeping postures and sleep habits. The characteristics of sleep behaviors vary from person to person.

  6. Nanoscale Structure-Property Relationships of Polyacrylonitrile/CNT Composites as a Function of Polymer Crystallinity and CNT Diameter.

    Science.gov (United States)

    Gissinger, Jacob R; Pramanik, Chandrani; Newcomb, Bradley; Kumar, Satish; Heinz, Hendrik

    2018-01-10

    Polyacrylonitrile (PAN)/carbon nanotube (CNT) composites are used as precursors for ultrastrong and lightweight carbon fibers. However, insights into the structure at the nanoscale and the relationships to mechanical and thermal properties have remained difficult to obtain. In this study, molecular dynamics simulation with accurate potentials and available experimental data were used to describe the influence of different degrees of PAN preorientation and CNT diameter on the atomic-scale structure and properties of the composites. The inclusion of CNTs in the polymer matrix is favored for an intermediate degree of PAN orientation and small CNT diameter whereas high PAN crystallinity and larger CNT diameter disfavor CNT inclusion. The glass transition at the CNT/PAN interface involves the release of rotational degrees of freedom of the polymer backbone and increased mobility of the protruding nitrile side groups in contact with the carbon nanotubes. The glass-transition temperature of the composite increases in correlation with the amount of CNT/polymer interfacial area per unit volume, i.e., in the presence of CNTs, for higher CNT volume fraction,  and inversely with CNT diameter. The increase in glass-transition temperature upon CNT addition is larger for PAN of lower crystallinity than for PAN of higher crystallinity. Interfacial shear strengths of the composites are higher for CNTs of smaller diameter and for PAN with preorientation, in correlation with more favorable CNT inclusion energies. The lowest interfacial shear strength was observed in amorphous PAN for the same CNT diameter. PAN with ∼75% crystallinity exhibited hexagonal patterns of nitrile groups near and far from the CNT interface which could influence carbonization into regular graphitic structures. The results illustrate the feasibility of near-quantitative insights into macroscale properties of polymer/CNT composites from simulations of nanometer-scale composite domains. Guidance is most

  7. The structure-property relationship of chiral 1,1'-binaphthyl-based polyoxometalates: TDDFT studies on the static first hyperpolarizabilities and the ECD spectra.

    Science.gov (United States)

    Wang, Jian-Ping; Yan, Li-Kai; Guan, Wei; Wen, Shi-Zheng; Su, Zhong-Min

    2012-02-01

    In this paper, density functional theory is used to investigate the linear optical and nonlinear optical (NLO) properties of a series of Λ-type chiral compounds composed of two Lindqvist-type polyoxometalates (POMs) linked by 1,1'-binaphthyl derivatives through arylimido. It shows that compound 1 which has two POMs on 6-6'-sites of 1,1'-binaphthyl possesses large static first hyperpolarizability and the strongest two-dimensional NLO response among studied compounds. The organic substituents on 2-2'-sites of 1,1'-binaphthyl twofold control the NLO responses of studied compounds. They act as electron acceptors or donors therefore suppress or enhance the NLO responses of studied compounds, and they restrain the torsion angles between two naphthyl rings at certain degrees which are inversely proportional to the NLO responses. Compound 6 with remarkable NLO response is obtained as ferrocene substitutes on 2-2'-sites of 1,1'-binaphthyl. Additionally, the electronic circular dichroism (ECD) spectra of studied compounds are simulated with CAM-B3LYP and B3LYP hybrid functionals. The results agree well with the experimental ECD spectra. The charge-transfer transitions from organic fragment to POM are responsible for the ECD differences between molecular hybrids and their precursors. It is confirmed that these Λ-type chiral compounds are potentially high-dimensional NLO materials and the structure-property relationship of these compounds is presented. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Prediction of the Formulation Dependence of the Glass Transition Temperature for Amine-Epoxy Copolymers Using a Quantitative Structure-Property Relationship Based on the AM1 Method

    National Research Council Canada - National Science Library

    Morrill, Jason

    2004-01-01

    A designer Quantitative Structure-Property Relationsbip (QSPR) based upon molecular properties calculated using the AM1 semi-empirical quantum mechanical metbod was developed to predict the glass transition temperature (Tg...

  9. Composition and structure-property relationships of chromium-diboride/molybdenum-disulphide PVD nanocomposite hard coatings deposited by pulsed magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Audronis, M.; Leyland, A.; Matthews, A. [The University of Sheffield, Department of Engineering Materials, Sheffield (United Kingdom); Kelly, P.J. [Manchester Metropolitan University, Surface Engineering Group, Manchester (United Kingdom)

    2008-04-15

    The composition and structure-property relationships of physical vapour deposited coatings containing mixtures of CrB{sub 2} and MoS{sub 2} are reported. The coatings were produced by pulsed magnetron sputtering of loosely-packed powder targets formed from a blend of chromium and boron powders, alloyed with 12.8, 18.9 and 24.0 atom percent MoS{sub 2}. Results of coating characterisation (by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and nanoindentation measurement of hardness and elastic modulus) revealed that increasing amounts of MoS{sub 2} produced the following effects: frustration of crystallisation and phase separation; a decrease in average grain sizes (from {proportional_to}5.5 to {proportional_to}4.3 nm) and a decrease in coating hardness (from {proportional_to}15 to {proportional_to}10 GPa). Scratch testing also showed that the load-bearing capability of coatings was altered; coatings possessing an intermediate concentration of MoS{sub 2} exhibited the best behaviour with no failure observed in mechanical testing, due to an optimal nanocomposite structure. The corrosion resistance (investigated by potentiodynamic polarisation tests) however tended to improve as more MoS{sub 2} was introduced. An investigation of the effects of generating an amorphous structure by adding Ti and C into Cr-B-MoS{sub 2} coatings revealed improved corrosion behaviour, which significantly exceeded that of uncoated stainless steel and CrB{sub 2}-coated samples. (orig.)

  10. Li-Carboxylate Anode Structure-Property Relationships from Molecular Modeling

    KAUST Repository

    Burkhardt, Stephen E.

    2013-01-22

    The full realization of a renewable energy strategy hinges upon electrical energy storage (EES). EES devices play a key role in storing energy from renewable sources (which are inherently intermittent), to efficient transmission (e.g., grid load-leveling), and finally into the electrification of transportation. Organic materials represent a promising class of electrode active materials for Li-ion and post-Li-ion batteries. Organics consist of low-cost, lightweight, widely available materials, and their properties can be rationally tuned using the well-established principles of organic chemistry. Within the class of organic EES materials, carboxylates distinguish themselves for Li-ion anode materials based on their observed thermal stability, rate capability, and high cyclability. Further, many of the carboxylates studied to date can be synthesized from renewable or waste feedstocks. This report begins with a preliminary molecular density-functional theory (DFT) study, in which the calculated molecular properties of a set of 12 known Li-ion electrode materials based on carboxylate and carbonyl redox couples are compared to literature data. Based on the agreement between theoretical and experimental data, an expanded study was undertaken to identify promising materials and establish design principles for anodes based on Li-carboxylate salts. Predictive computational studies represent an important step forward for the identification of organic anode materials. © 2012 American Chemical Society.

  11. The structural properties of sustainable, continuous change

    DEFF Research Database (Denmark)

    Håkonsson, Dorthe Døjbak; Klaas, Johann Peter; Carroll, Timothy

    2013-01-01

    Recent studies show that the relationship between structure and inertia in changing environments may be more complex than previously held and that the theoretical logics tying inertia with flexibility and efficiency remain incomplete. Using a computational model, this article aims to clarify...... this relationship by exploring what structural properties enable continuous change in inertia-generating organizations and what their performance consequences are in dynamic environments. The article has three main findings: First, employing managers who anticipate change is not enough to generate continuous change......; it is also necessary to raise both the rate of responsiveness and desired performance. Second, continuous change increases average organizational performance and reduces its variation. Third, organizations’ capacity for continuous change is counterintuitively limited by the organizations’ capacity to build...

  12. A review of the structure-property relationships in lead-free piezoelectric (1−x)Na0.5Bi0.5TiO3–(x)BaTiO3

    International Nuclear Information System (INIS)

    McQuade, Ryan R.; Dolgos, Michelle R.

    2016-01-01

    Piezoelectric materials are increasingly being investigated for energy harvesting applications where (1−x)Na 0.5 Bi 0.5 TiO 3 –(x)BaTiO 3 (NBT-BT) is an important lead-free piezoelectric material with potential to be used as an actuator in energy harvesting devices. Much effort has been put into modifying NBT-BT to tune the properties for specific applications, but there is currently no consensus regarding the structure-property relationships in this material, making targeted, rational design a major challenge. In this review, we will summarize the current body of knowledge of NBT-BT and discuss contradicting studies, unresolved problems, and future directions in the field. - Graphical abstract: This review of (1−x)Na 0.5 Bi 0.5 TiO 3 –(x)BaTiO 3 (NBT-BT) summarizes the large body of literature regarding the structure-property relationships of this complex material. We highlight structural studies of the average and local structures of both unpoled and poled samples of NBT-BT at its morphotropic phase boundary and discuss them in context of the observed piezoelectric properties. - Highlights: • Local and average structure of NBT-BT at morphotropic phase boundary is reviewed. • Average structure of poled and unpoled samples of NBT-BT is discussed. • Structure-property relationships in NBT-BT and future directions are summarized.

  13. Process-structure-property relationships of micron thick gadolinium oxide films deposited by reactive electron beam-physical vapor deposition (EB-PVD)

    Science.gov (United States)

    Grave, Daniel A.

    Gadolinium oxide (Gd2O3) is an attractive material for solid state neutron detection due to gadolinium's high thermal neutron capture cross section. Development of neutron detectors based on Gd2 O3 requires sufficiently thick films to ensure neutron absorption. In this dissertation work, the process-structure-property relationships of micron thick Gd2O3 films deposited by reactive electron-beam physical vapor deposition (EB-PVD) were studied. Through a systematic design of experiments, fundamental studies were conducted to determine the effects of processing conditions such as deposition temperature, oxygen flow rate, deposition rate, and substrate material on Gd2O3 film crystallographic phase, texture, morphology, grain size, density, and surface roughness. Films deposited at high rates (> 5 A/s) were examined via x-ray diffraction (XRD) and Raman spectroscopy. Quantitative phase volume calculations were performed via a Rietveld refinement technique. All films deposited at high rates were found to be fully monoclinic or mixed cubic/monoclinic phase. Generally, increased deposition temperature and increased oxygen flow resulted in increased cubic phase volume. As film thickness increased, monoclinic phase volume increased. Grazing incidence x-ray diffraction (GIXRD) depth profiling analysis showed that cubic phase was only present under large incidence angle (large penetration depth) measurements, and after a certain point, only monoclinic phase was grown. This was confirmed by transmission electron microscopy (TEM) analysis with selected area diffraction (SAD). Based on this information, a large compressive stress was hypothesized to cause the formation of the monoclinic phase and this hypothesis was confirmed by demonstrating the existence of a stress induced phase transition. An experiment was designed to introduce compressive stress into the Gd2O 3 films via ion beam assisted deposition (IBAD). This allowed for systematic increase in compressive stress while

  14. Evaluation of a quantitative structure-property relationship (QSPR) for predicting mid-visible refractive index of secondary organic aerosol (SOA).

    Science.gov (United States)

    Redmond, Haley; Thompson, Jonathan E

    2011-04-21

    In this work we describe and evaluate a simple scheme by which the refractive index (λ = 589 nm) of non-absorbing components common to secondary organic aerosols (SOA) may be predicted from molecular formula and density (g cm(-3)). The QSPR approach described is based on three parameters linked to refractive index-molecular polarizability, the ratio of mass density to molecular weight, and degree of unsaturation. After computing these quantities for a training set of 111 compounds common to atmospheric aerosols, multi-linear regression analysis was conducted to establish a quantitative relationship between the parameters and accepted value of refractive index. The resulting quantitative relationship can often estimate refractive index to ±0.01 when averaged across a variety of compound classes. A notable exception is for alcohols for which the model consistently underestimates refractive index. Homogenous internal mixtures can conceivably be addressed through use of either the volume or mole fraction mixing rules commonly used in the aerosol community. Predicted refractive indices reconstructed from chemical composition data presented in the literature generally agree with previous reports of SOA refractive index. Additionally, the predicted refractive indices lie near measured values we report for λ = 532 nm for SOA generated from vapors of α-pinene (R.I. 1.49-1.51) and toluene (R.I. 1.49-1.50). We envision the QSPR method may find use in reconstructing optical scattering of organic aerosols if mass composition data is known. Alternatively, the method described could be incorporated into in models of organic aerosol formation/phase partitioning to better constrain organic aerosol optical properties.

  15. A study of structural properties of gene network graphs for mathematical modeling of integrated mosaic gene networks.

    Science.gov (United States)

    Petrovskaya, Olga V; Petrovskiy, Evgeny D; Lavrik, Inna N; Ivanisenko, Vladimir A

    2017-04-01

    Gene network modeling is one of the widely used approaches in systems biology. It allows for the study of complex genetic systems function, including so-called mosaic gene networks, which consist of functionally interacting subnetworks. We conducted a study of a mosaic gene networks modeling method based on integration of models of gene subnetworks by linear control functionals. An automatic modeling of 10,000 synthetic mosaic gene regulatory networks was carried out using computer experiments on gene knockdowns/knockouts. Structural analysis of graphs of generated mosaic gene regulatory networks has revealed that the most important factor for building accurate integrated mathematical models, among those analyzed in the study, is data on expression of genes corresponding to the vertices with high properties of centrality.

  16. Local structural properties and attribute characteristisc in 2-mode networks: p* models to map choices of theater events

    NARCIS (Netherlands)

    Agneessens, F.; Roose, H.

    2008-01-01

    Choices of plays made by theatergoers can be considered as a 2-mode or affiliation network. In this article we illustrate how p* models (an exponential family of distributions for random graphs) can be used to uncover patterns of choices. Based on audience research in three theater institutions in

  17. Monte Carlo thermodynamic and structural properties of the TIP4P water model: dependence on the computational conditions

    Directory of Open Access Journals (Sweden)

    João Manuel Marques Cordeiro

    1998-11-01

    Full Text Available Classical Monte Carlo simulations were carried out on the NPT ensemble at 25°C and 1 atm, aiming to investigate the ability of the TIP4P water model [Jorgensen, Chandrasekhar, Madura, Impey and Klein; J. Chem. Phys., 79 (1983 926] to reproduce the newest structural picture of liquid water. The results were compared with recent neutron diffraction data [Soper; Bruni and Ricci; J. Chem. Phys., 106 (1997 247]. The influence of the computational conditions on the thermodynamic and structural results obtained with this model was also analyzed. The findings were compared with the original ones from Jorgensen et al [above-cited reference plus Mol. Phys., 56 (1985 1381]. It is notice that the thermodynamic results are dependent on the boundary conditions used, whereas the usual radial distribution functions g(O/O(r and g(O/H(r do not depend on them.

  18. Geometry and Structural Properties for the Controls Advanced Research Turbine (CART) from Model Tuning: August 25, 2003--November 30, 2003

    Energy Technology Data Exchange (ETDEWEB)

    Stol, K. A.

    2004-09-01

    The Controls Advanced Research Turbine (CART) is a modified Westinghouse WWG-0600 machine rated at 600 kW. It is located at the National Wind Technology Center (NWTC) in Boulder, Colorado, and has been installed to test new control schemes for power and load regulation. In its original configuration, the WWG-0600 uses a synchronous generator, fluid coupling, and hydraulic collective pitch actuation. However, the CART is fitted with an induction generator, rigid coupling, and individual electromechanical pitch actuators. The rotor runs upwind of the tower and consists of two blades and a teetering hub. In order to design advanced control schemes for the CART, representative computational models are essential.

  19. Phase interaction in the metal-oxide melts-gas system the modeling of structure, properties and processes

    CERN Document Server

    Boronenkov, V; Leontiev, L

    2012-01-01

    This monograph describes mathematical models that enable prediction of phase compositions for various technological processes, as developed on the base of a complex physico-chemical analysis of reaction. It studies thermodynamics and kinetics of specific stages of complex pyrometallurgical processes involving boron, carbon, sulfur, tungsten, phosphorus, and many more, as well as their exposure to all sorts of factors. First and foremost, this enables to optimize processes and technologies at the stage of design, while traditional empirical means of development of new technologies are basically incapable of providing an optimal solution. Simulation results of metals and alloys production, welding and coating technologies allow obtaining materials with pre-given composition, structure and properties in a cost-saving and conscious manner. Moreover, a so-called "inverse problem", i.e., selecting source materials which would ensure the required results, cannot be solved by any other means.

  20. Correlation between acoustical and structural properties of glasses: Extension of Abd El-Moneim model for bioactive silica based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Abd El-Moneim, Amin, E-mail: aminabdelmoneim@hotmail.com

    2016-04-15

    Correlation between room temperature ultrasonic attenuation coefficient and the most significant structural parameters has been studied in the bioactive silica based glasses, for the first time. The correlation has been carried out in the quaternary SiO{sub 2}–Na{sub 2}O–CaO–P{sub 2}O{sub 5} glass system using the two semi-empirical formulas, which have been presented recently by the author. Changes in the elastic properties, related to the substitution of SiO{sub 2} by alkali Na{sub 2}O and alkaline earth CaO oxides, have also been deduced by evaluating the mean atomic volume, packing density, fractal bond connectivity and density of the analogous crystalline structure. Furthermore, values of the theoretical elastic moduli have been calculated on the basis of Makishima-Mackenzie theory and compared with the corresponding observed values. Results show that the correlation between ultrasonic attenuation coefficient and the oxygen density, average atomic ring size, first-order stretching force constant and experimental bulk modulus was achieved at 5 MHz frequency. Values of the theoretically calculated shear modulus are in excellent correlation (C. R. ≻95%) with the corresponding experimental ones. The divergence between the theoretical and experimental values of bulk modulus has been discussed. - Highlights: • Abd El-Moneim model was extended for bioactive glasses. • Ultrasonic attenuation was correlated with structural parameters. • Correlation was carried out in Si–Na–Ca–P glasses. • The model is valid for all investigated glass samples. • Agreement between theoretical and experimental elastic moduli was studied.

  1. The influence of severe prolonged exercise restriction on the mechanical and structural properties of bone in an avian model.

    Science.gov (United States)

    Shipov, Anna; Sharir, Amnon; Zelzer, Elazar; Milgram, Joshua; Monsonego-Ornan, Efrat; Shahar, Ron

    2010-02-01

    Many studies have described the effects of exercise restriction on the mammalian skeleton. In particular, human and animal models have shown that reduction in weight bearing leads to generalised bone loss and deterioration of its mechanical properties. The aim of this study was to assess the effect of prolonged exercise restriction coupled with heavy calcium demands on the micro-structural, compositional and mechanical properties of the avian skeleton. The tibiae and humeri of 2-year-old laying hens housed in conventional caging (CC) and free-range (FR) housing systems were compared by mechanical testing and micro-computed tomography (microCT) scanning. Analyses of cortical, cancellous and medullary bone were performed. Mechanical testing revealed that the tibiae and humeri of birds from the FR group had superior mechanical properties relative to those of the CC group, and microCT scanning indicated larger cortical and lower medullary regions in FR group bones. Cancellous bone analysis revealed higher trabecular thickness and a higher bone volume fraction in the FR group, but no difference in mineral density. The biomechanical superiority of bones from the FR group was primarily due to structural rather than compositional differences, and this was reflected in both the cortical and cancellous components of the bones. The study demonstrated that prolonged exercise restriction in laying hens resulted in major structural and mechanical effects on the bird skeleton. Copyright (c) 2008 Elsevier Ltd. All rights reserved.

  2. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts

    Science.gov (United States)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-04-01

    observed enhancement of the catalytic activity of PtxRu100-x alloy NPs at x ~ 50. Implications of so-established relationships between the atomic structure and catalytic activity of Pt-Ru alloy NPs on efforts aimed at improving further the latter by tuning-up the former are discussed and the usefulness of detailed NP structure studies to advancing science and technology of metallic NPs - exemplified.An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic

  3. Use of quantitative-structure property relationship (QSPR) and artificial neural network (ANN) based approaches for estimating the octanol-water partition coefficients of the 209 chlorinated trans-azobenzene congeners.

    Science.gov (United States)

    Wilczyńska-Piliszek, Agata J; Piliszek, Sławomir; Falandysz, Jerzy

    2012-01-01

    Polychlorinated azobenzenes (PCABs) can be found as contaminant by products in 3,4-dichloroaniline and its derivatives and in the herbicides Diuron, Linuron, Methazole, Neburon, Propanil and SWEP. Trans congeners of PCABs are physically and chemically more stable and so are environmentally relevant, when compared to unstable cis congeners. In this study, to fulfill gaps on environmentally relevant partitioning properties of PCABs, the values of n-octanol/water partition coefficients (log K(OW)) have been determined for 209 congeners of chloro-trans-azobenzene (Ct-AB) by means of quantitative structure-property relationship (QSPR) approach and artificial neural networks (ANN) predictive ability. The QSPR methods used based on geometry optimalization and quantum-chemical structural descriptors, which were computed on the level of density functional theory (DFT) using B3LYP functional and 6-311++G basis set in Gaussian 03 and of the semi-empirical quantum chemistry method (PM6) of the molecular orbital package (MOPAC). Polychlorinated dibenzo-p-dioxins (PCDDs), -furans (PCDFs) and -biphenyls (PCBs), to which PCABs are related, were reference compounds in this study. An experimentally obtained data on physical and chemical properties of PCDD/Fs and PCBs were reference data for ANN predictions of log K(OW) values of Ct-ABs in this study. Both calculation methods gave similar results in term of absolute log K(OW) values, while the models generated by PM6 are considered highly efficient in time spent, when compared to these by DFT. The estimated log K(OW) values of 209 Ct-ABs varied between 5.22-5.57 and 5.45-5.60 for Mono-, 5.56-6.00 and 5.59-6.07 for Di-, 5.89-6.56 and 5.91-6.46 for Tri-, 6.10-7.05 and 6.13-6.80 for Tetra-, 6.43-7.39 and 6.48-7.14 for Penta-, 6.61-7.78 and 6.98-7.42 for Hexa-, 7.41-7.94 and 7.34-7.86 for Hepta-, 7.99-8.17 and 7.72-8.20 for Octa-, 8.35-8.42 and 8.10-8.62 for NonaCt-ABs, and 8.52-8.60 and 8.81-8.83 for DecaCt-AB. These log K(OW) values

  4. Elucidating the structure-property relationships of donor-π-acceptor dyes for dye-sensitized solar cells (DSSCs) through rapid library synthesis by a one-pot procedure.

    Science.gov (United States)

    Fuse, Shinichiro; Sugiyama, Sakae; Maitani, Masato M; Wada, Yuji; Ogomi, Yuhei; Hayase, Shuzi; Katoh, Ryuzi; Kaiho, Tatsuo; Takahashi, Takashi

    2014-08-18

    The creation of organic dyes with excellent high power conversion efficiency (PCE) is important for the further improvement of dye-sensitized solar cells. We wish to describe the rapid synthesis of a 112-membered donor-π-acceptor dye library by a one-pot procedure, evaluation of PCEs, and elucidation of structure-property relationships. No obvious correlations between ε, and the η were observed, whereas the HOMO and LUMO levels of the dyes were critical for η. The dyes with a more positive E(HOMO), and with an E(LUMO)dyes; nevertheless, that was not sufficient for identifying the best combination of donor, π, and acceptor blocks. Combinatorial synthesis and evaluation was important for identifying the best dye. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Identifying Structure-Property Relationships Through DREAM.3D Representative Volume Elements and DAMASK Crystal Plasticity Simulations: An Integrated Computational Materials Engineering Approach

    Science.gov (United States)

    Diehl, Martin; Groeber, Michael; Haase, Christian; Molodov, Dmitri A.; Roters, Franz; Raabe, Dierk

    2017-05-01

    Predicting, understanding, and controlling the mechanical behavior is the most important task when designing structural materials. Modern alloy systems—in which multiple deformation mechanisms, phases, and defects are introduced to overcome the inverse strength-ductility relationship—give raise to multiple possibilities for modifying the deformation behavior, rendering traditional, exclusively experimentally-based alloy development workflows inappropriate. For fast and efficient alloy design, it is therefore desirable to predict the mechanical performance of candidate alloys by simulation studies to replace time- and resource-consuming mechanical tests. Simulation tools suitable for this task need to correctly predict the mechanical behavior in dependence of alloy composition, microstructure, texture, phase fractions, and processing history. Here, an integrated computational materials engineering approach based on the open source software packages DREAM.3D and DAMASK (Düsseldorf Advanced Materials Simulation Kit) that enables such virtual material development is presented. More specific, our approach consists of the following three steps: (1) acquire statistical quantities that describe a microstructure, (2) build a representative volume element based on these quantities employing DREAM.3D, and (3) evaluate the representative volume using a predictive crystal plasticity material model provided by DAMASK. Exemplarily, these steps are here conducted for a high-manganese steel.

  6. Interpretation of Quantitative Structure-Activity Relationship Models: Past, Present, and Future.

    Science.gov (United States)

    Polishchuk, Pavel

    2017-11-27

    This paper is an overview of the most significant and impactful interpretation approaches of quantitative structure-activity relationship (QSAR) models, their development, and application. The evolution of the interpretation paradigm from "model → descriptors → (structure)" to "model → structure" is indicated. The latter makes all models interpretable regardless of machine learning methods or descriptors used for modeling. This opens wide prospects for application of corresponding interpretation approaches to retrieve structure-property relationships captured by any models. Issues of separate approaches are discussed as well as general issues and prospects of QSAR model interpretation.

  7. Structure-Property Relationship of Thermoset Nanocomposites

    NARCIS (Netherlands)

    Faraz, M.I.

    2013-01-01

    In this thesis we report the synthesis, characterization and thermo-mechanical properties of a high-temperature resistant themoset nanocomposite system based on an aero-space-grade Bismaleimide resin. Various processing techniques with various fillers are used. The emphasis is on establishing the

  8. Structure Property Relationships in Liquid Crystalline Thermosets

    Science.gov (United States)

    2003-04-25

    and 6 different flexible tails. Characterization of the thermal transitions in the uncured monomers shows the expected trends : monomers with both long...Arthur J. Gavrin and Elliot P. Douglas, “Cure behavior of liquid crystalline thermosets”, poster presentation at POLY Millenial 2000, Waikoloa, HI

  9. Structural property relationships in conjugated polymers

    Science.gov (United States)

    Lynch, P.; O'Neill, L.; Whelan, J.; McNamara, M.; Byrne, H. J.

    2005-06-01

    The synthesis of a series of PPV derivative polymers by the Wittig-Horner reaction is described. The structure of each polymer is varied and the effects of these variations on the optical properties is explored. The effects of alkyloxy side chains is observed between the PPV derivatives Poly(-p-phenylvinylene-co-2,5-bis-octyloxy phenylvinylene.) PPV-OPV and Poly (para-2,5-bis-(n-octyloxy)-phenylvinylene) POPV. The phenyl units of the soluble PPV derivative POPV are replaced by alternate naphthyl units in the polymer Poly(2,5-bis(n-octyloxy)-1,4-phenylene vinylene-1,5-bis(n-octyloxy)-2,6-naphthylene vinylene) POPN-ONV and then fully by naphthyl units in Poly(2,6-bis-(n-octyloxy)-1,5-NaphthyleneVinylene) PONV. The addition of alkyloxy sidechains served to red shift the fluorescence emission as expected. The systematic conversion of phenyl to naphthyl units blue shifted the emission considerably while reducing the Stokes shift. There is evidence to suggest some localization of the pi electrons over the aromatic units of the polymer backbone. PONV is shown to have greater stability towards photo-oxidation then either POPV or PPV-OPV.

  10. Structure-Property Relationships in Isotactic Polypropylene

    NARCIS (Netherlands)

    van der Meer, D.W.

    2003-01-01

    This thesis is the result of a project initiated by the Dutch Polymer Institute (DPI). The general theme involves "molecular characterization and morphology development in polypropylene obtained by metallocene polymerization". Throughout this investigation, the general theme was shaped and filled in

  11. Spaghetti Bridges: Modeling Linear Relationships

    Science.gov (United States)

    Kroon, Cindy D.

    2016-01-01

    Mathematics and science are natural partners. One of many examples of this partnership occurs when scientific observations are made, thus providing data that can be used for mathematical modeling. Developing mathematical relationships elucidates such scientific principles. This activity describes a data-collection activity in which students employ…

  12. A review of the structure-property relationships in lead-free piezoelectric (1−x)Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}–(x)BaTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    McQuade, Ryan R.; Dolgos, Michelle R., E-mail: Michelle.Dolgos@oregonstate.edu

    2016-10-15

    Piezoelectric materials are increasingly being investigated for energy harvesting applications where (1−x)Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}–(x)BaTiO{sub 3} (NBT-BT) is an important lead-free piezoelectric material with potential to be used as an actuator in energy harvesting devices. Much effort has been put into modifying NBT-BT to tune the properties for specific applications, but there is currently no consensus regarding the structure-property relationships in this material, making targeted, rational design a major challenge. In this review, we will summarize the current body of knowledge of NBT-BT and discuss contradicting studies, unresolved problems, and future directions in the field. - Graphical abstract: This review of (1−x)Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}–(x)BaTiO{sub 3} (NBT-BT) summarizes the large body of literature regarding the structure-property relationships of this complex material. We highlight structural studies of the average and local structures of both unpoled and poled samples of NBT-BT at its morphotropic phase boundary and discuss them in context of the observed piezoelectric properties. - Highlights: • Local and average structure of NBT-BT at morphotropic phase boundary is reviewed. • Average structure of poled and unpoled samples of NBT-BT is discussed. • Structure-property relationships in NBT-BT and future directions are summarized.

  13. Intermetallics structures, properties, and statistics

    CERN Document Server

    Steurer, Walter

    2016-01-01

    The focus of this book is clearly on the statistics, topology, and geometry of crystal structures and crystal structure types. This allows one to uncover important structural relationships and to illustrate the relative simplicity of most of the general structural building principles. It also allows one to show that a large variety of actual structures can be related to a rather small number of aristotypes. It is important that this book is readable and beneficial in the one way or another for everyone interested in intermetallic phases, from graduate students to experts in solid-state chemistry/physics/materials science. For that purpose it avoids using an enigmatic abstract terminology for the classification of structures. The focus on the statistical analysis of structures and structure types should be seen as an attempt to draw the background of the big picture of intermetallics, and to point to the white spots in it, which could be worthwhile exploring. This book was not planned as a textbook; rather, it...

  14. Simulant molecules with trivalent or pentavalent phosphorus atoms: bond dissociation energies and other thermodynamic and structural properties from quantum chemical models.

    Science.gov (United States)

    Hahn, David K; RaghuVeer, Krishans S; Ortiz, J V

    2011-08-04

    The CBS-QB3 and G4 thermochemical models have been used to generate energetic, structural, and spectroscopic data on a set of molecules with trivalent or pentavalent phosphorus atoms that can serve as simulants of chemical warfare agents. Based on structural data, the conformational stabilities of these molecules are explained in terms of the anomeric interaction within the OPOC and OPSC fragments. For those cases where experimental data are available, comparisons have been made between calculated and previously reported vibrational frequencies. All varieties of bond dissociation energies have been examined except those for C-H and P═O bonds. In trivalent phosphorus molecules, the O-C and S-C bonds have the lowest dissociation energies. In the pentavalent phosphorus set, the S-C bonds, followed by P-S bonds, have the lowest dissociation energies. In the fluorinated simulant molecules, the P-F bond is strongest, and the P-C or O-C bonds are weakest. © 2011 American Chemical Society

  15. Accurate predictions of population-level changes in sequence and structural properties of HIV-1 Env using a volatility-controlled diffusion model.

    Science.gov (United States)

    DeLeon, Orlando; Hodis, Hagit; O'Malley, Yunxia; Johnson, Jacklyn; Salimi, Hamid; Zhai, Yinjie; Winter, Elizabeth; Remec, Claire; Eichelberger, Noah; Van Cleave, Brandon; Puliadi, Ramya; Harrington, Robert D; Stapleton, Jack T; Haim, Hillel

    2017-04-01

    The envelope glycoproteins (Envs) of HIV-1 continuously evolve in the host by random mutations and recombination events. The resulting diversity of Env variants circulating in the population and their continuing diversification process limit the efficacy of AIDS vaccines. We examined the historic changes in Env sequence and structural features (measured by integrity of epitopes on the Env trimer) in a geographically defined population in the United States. As expected, many Env features were relatively conserved during the 1980s. From this state, some features diversified whereas others remained conserved across the years. We sought to identify "clues" to predict the observed historic diversification patterns. Comparison of viruses that cocirculate in patients at any given time revealed that each feature of Env (sequence or structural) exists at a defined level of variance. The in-host variance of each feature is highly conserved among individuals but can vary between different HIV-1 clades. We designate this property "volatility" and apply it to model evolution of features as a linear diffusion process that progresses with increasing genetic distance. Volatilities of different features are highly correlated with their divergence in longitudinally monitored patients. Volatilities of features also correlate highly with their population-level diversification. Using volatility indices measured from a small number of patient samples, we accurately predict the population diversity that developed for each feature over the course of 30 years. Amino acid variants that evolved at key antigenic sites are also predicted well. Therefore, small "fluctuations" in feature values measured in isolated patient samples accurately describe their potential for population-level diversification. These tools will likely contribute to the design of population-targeted AIDS vaccines by effectively capturing the diversity of currently circulating strains and addressing properties of variants

  16. Relationships between models of concurrency

    DEFF Research Database (Denmark)

    Nielsen, Mogens; Sassone, Vladimiro; Winskel, Glynn

    1994-01-01

    Models for concurrency can be classified with respect to the three relevant parameters: behaviour/system, interleaving/noninterleaving, linear/branching time. When modelling a process, a choice concerning such parameters corresponds to choosing the level of abstraction of the resulting semantics....

  17. Foundations of compositional models: structural properties

    Czech Academy of Sciences Publication Activity Database

    Jiroušek, Radim; Kratochvíl, Václav

    2015-01-01

    Roč. 44, č. 1 (2015), s. 2-25 ISSN 0308-1079 R&D Projects: GA ČR GA13-20012S Grant - others:GA ČR(CZ) GAP403/12/2175 Program:GA Institutional support: RVO:67985556 Keywords : multidimensional distribution * conditional independence * composition * semigraphoid properties * running intersection property Subject RIV: BA - General Mathematics Impact factor: 1.677, year: 2015 http://library.utia.cas.cz/separaty/2015/MTR/jirousek-0442412.pdf

  18. Designing Customer Relationship Management Model in Hospital

    OpenAIRE

    Mohammad Abbaszadeh; Roohollah Askari; Morad Alizadeh; Mohammad Amin Bahrami

    2017-01-01

    Background: Customer relationship management is a modern marketing concept which is also considered as a successful business strategy. The present study aimed to design a customer relationship management model in the hospital. Methods: The study is an applied research performed in 2 phases of 1) texts investigation and 2) the experts' opinions to achieve consensus. Data were analyzed using SPSS 18 software along with descriptive statistics. Results: The designed model included areas of ...

  19. Cellulose nanomaterials review: structure, properties and nanocomposites

    Science.gov (United States)

    Robert J. Moon; Ashlie Martini; John Nairn; John Simonsen; Jeff Youngblood

    2011-01-01

    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The...

  20. Adaptive regression for modeling nonlinear relationships

    CERN Document Server

    Knafl, George J

    2016-01-01

    This book presents methods for investigating whether relationships are linear or nonlinear and for adaptively fitting appropriate models when they are nonlinear. Data analysts will learn how to incorporate nonlinearity in one or more predictor variables into regression models for different types of outcome variables. Such nonlinear dependence is often not considered in applied research, yet nonlinear relationships are common and so need to be addressed. A standard linear analysis can produce misleading conclusions, while a nonlinear analysis can provide novel insights into data, not otherwise possible. A variety of examples of the benefits of modeling nonlinear relationships are presented throughout the book. Methods are covered using what are called fractional polynomials based on real-valued power transformations of primary predictor variables combined with model selection based on likelihood cross-validation. The book covers how to formulate and conduct such adaptive fractional polynomial modeling in the s...

  1. Finite Element Estimation of Meteorite Structural Properties

    Science.gov (United States)

    Hart, Kenneth Arthur

    2015-01-01

    The goal of the project titled Asteroid Threat Assessment at NASA Ames Research Center is to develop risk assessment tools. The expertise in atmospheric entry in the Entry Systems and Technology Division is being used to describe the complex physics of meteor breakup in the atmosphere. The breakup of a meteor is dependent on its structural properties, including homogeneity of the material. The present work describes an 11-week effort in which a literature survey was carried for structural properties of meteoritic material. In addition, the effect of scale on homogeneity isotropy was studied using a Monte Carlo approach in Nastran. The properties were then in a static structural response simulation of an irregularly-shape meteor (138-scale version of Asteroid Itokawa). Finally, an early plan was developed for doctoral research work at Georgia Tech. in the structural failure fragmentation of meteors.

  2. The equilibrium model of relationship maintenance.

    Science.gov (United States)

    Murray, Sandra L; Holmes, John G; Griffin, Dale W; Derrick, Jaye L

    2015-01-01

    A new equilibrium model of relationship maintenance is proposed. People can protect relationship bonds by practicing 3 threat-mitigation rules: Trying to accommodate when a partner is hurtful, ensuring mutual dependence, and resisting devaluing a partner who impedes one's personal goals. A longitudinal study of newlyweds revealed evidence for the equilibrium model, such that relationship well-being (as indexed by satisfaction and commitment) declining from its usual state predicted increased threat-mitigation; in turn, increasing threat mitigation from its usual state predicted increased relationship well-being. Longitudinal findings further revealed adaptive advantages to uncertain trust. First, the match between trust and partner-risk predicted the trajectory of threat mitigation over time. People who hesitated to trust a high-risk partner became more likely to mitigate threats over 3 years, but people who hesitated to trust a safe partner became less likely to mitigate threats. The match between threat mitigation and partner-risk also predicted when being less trusting eroded later relationship well-being. Namely, when women paired with high-risk partners became more likely to mitigate threats, being less trusting at marriage lost its capacity to erode later relationship well-being. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  3. Process, structure, property and applications of metallic glasses

    Directory of Open Access Journals (Sweden)

    B. Geetha Priyadarshini

    2016-07-01

    Full Text Available Metallic glasses (MGs are gaining immense technological significance due to their unique structure-property relationship with renewed interest in diverse field of applications including biomedical implants, commercial products, machinery parts, and micro-electro-mechanical systems (MEMS. Various processing routes have been adopted to fabricate MGs with short-range ordering which is believed to be the genesis of unique structure. Understanding the structure of these unique materials is a long-standing unsolved mystery. Unlike crystalline counterpart, the outstanding properties of metallic glasses owing to the absence of grain boundaries is reported to exhibit high hardness, excellent strength, high elastic strain, and anti-corrosion properties. The combination of these remarkable properties would significantly contribute to improvement of performance and reliability of these materials when incorporated as bio-implants. The nucleation and growth of metallic glasses is driven by thermodynamics and kinetics in non-equilibrium conditions. This comprehensive review article discusses the various attributes of metallic glasses with an aim to understand the fundamentals of relationship process-structure-property existing in such unique class of material.

  4. Structure-property relationships based on Hammett constants in cyclometalated iridium(III) complexes: their application to the design of a fluorine-free FIrPic-like emitter.

    Science.gov (United States)

    Frey, Julien; Curchod, Basile F E; Scopelliti, Rosario; Tavernelli, Ivano; Rothlisberger, Ursula; Nazeeruddin, Mohammad K; Baranoff, Etienne

    2014-04-21

    While phosphorescent cyclometalated iridium(iii) complexes have been widely studied, only correlations between oxidation potential EOX and Hammett constant σ, and between the redox gap (ΔEREDOX = EOX-ERED) and emission or absorption wavelength (λabs, λem) have been reported. We present now a quantitative model based on Hammett parameters that rationalizes the effect of the substituents on the properties of cyclometalated iridium(iii) complexes. This simple model allows predicting the apparent redox potentials as well as the electrochemical gap of homoleptic complexes based on phenylpyridine ligands with good accuracy. In particular, the model accounts for the unequal effect of the substituents on both the HOMO and the LUMO energy levels. Consequently, the model is used to anticipate the emission maxima of the corresponding complexes with improved reliability. We demonstrate in a series of phenylpyridine emitters that electron-donating groups can effectively replace electron-withdrawing substituents on the orthometallated phenyl to induce a blue shift of the emission. This result is in contrast with the common approach that uses fluorine to blue shift the emission maximum. Finally, as a proof of concept, we used electron-donating substituents to design a new fluorine-free complex, referred to as EB343, matching the various properties, namely oxidation and reduction potentials, electrochemical gap and emission profile, of the standard sky-blue emitter FIrPic.

  5. THREE-DIMENSIONAL QUANTITATIVE STRUCTURE-PROPERTY RELATIONSHIP (3D-QSPR) MODELS FOR PREDICTION OF THERMODYNAMIC PROPERTIES OF POLYCHLORINATED BIPHENYLS (PCBS): ENTHALPY OF SUBLIMATION. (R826133)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  6. THREE-DIMENSIONAL QUANTITATIVE STRUCTURE-PROPERTY RELATIONSHIP (3D-QSPR) MODELS FOR PREDICTION OF THERMODYNAMIC PROPERTIES OF POLYCHLORINATED BIPHENYLS (PCBS): ENTHALPY OF VAPORIZATION. (R826133)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. Structural properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Soon, Yee Yeen; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    We report a systematic study of the structural properties of rhodium clusters at the atomistic level. A novel global-minimum search algorithm, known as parallel tempering multicanonical basin hopping plus genetic algorithm (PTMBHGA), is used to obtain the geometrical structures with lowest minima at the semi-empirical level where Gupta potential is used to describe the atomic interaction among the rhodium atoms. These structures are then re-optimized at the density functional theory (DFT) level with exchange-correlation energy approximated by Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA). The structures are optimized for different spin multiplicities. The ones with lowest energies will be taken as ground-state structures. In most cases, we observe only minor changes in the geometry and bond length of the clusters as a result of DFT-level re-optimization. Only in some limited cases, the initial geometries obtained from the PTMBHGA are modified by the re-optimization. The variation of structural properties, such as ground-state geometry, symmetry and binding energy, with respect to the cluster size is studied and agreed well with other results available in the literature.

  8. Rational Formulation of Alternative Fuels using QSPR Methods: Application to Jet Fuels Développement d’un outil d’aide à la formulation des carburants alternatifs utilisant des méthodes QSPR (Quantitative Structure Property Relationship: application aux carburéacteurs

    Directory of Open Access Journals (Sweden)

    Saldana D.A.

    2013-06-01

    Full Text Available Alternative fuels are a promising solution for road transport but also for aircraft. In the aviation field, a huge amount of work has been done in the past years with the approval to use up to 50 % by volume of SPK (Synthetic Paraffinic Kerosene in blends with conventional fossil Jet A-1. SPK are Fischer-Tropsch (FT fuels but also Hydroprocessed Esters and Fatty Acids (HEFA. However, these alternative fuels can have different chemical properties depending on the process used for their production. These properties include normal to iso paraffin ratio, carbon chain length and level of branching. R&D studies of alternative fuels are based on the evaluation of products coming from identified production processes. However, it appears that a better way of studying them could be firstly to determine the best chemical composition regarding aviation problems and secondly to find the best process and finishing process in order to obtain such a product. The objective of this work is to design a tool that aims to guide the future formulation of alternative fuels for aviation through the prediction of targeted physical properties. Thus, it is proposed to apply a methodology that identifies relationships between the structure and properties of a molecule (QSPR for Quantitative Structure Property Relationship, with the aim of establishing predictive models. These models will be built for hydrocarbons (normal and iso paraffins, naphthenes, aromatics, etc. and oxygenated compounds (esters and alcohols. For aviation, oxygenated compounds are not considered as a drop-in fuel. It could be seen as a disruptive solution in a long term view. There are concerns with oxygenates in aviation that are covered in this paper such as the flash point but others such as the energetic content, the water affinity that are not taken into account in this paper. The properties currently studied are flash point, cetane number, density and viscosity. The data sets will contain data

  9. Diamond nanowires: fabrication, structure, properties, and applications.

    Science.gov (United States)

    Yu, Yuan; Wu, Liangzhuan; Zhi, Jinfang

    2014-12-22

    C(sp(3) )C-bonded diamond nanowires are wide band gap semiconductors that exhibit a combination of superior properties such as negative electron affinity, chemical inertness, high Young's modulus, the highest hardness, and room-temperature thermal conductivity. The creation of 1D diamond nanowires with their giant surface-to-volume ratio enhancements makes it possible to control and enhance the fundamental properties of diamond. Although theoretical comparisons with carbon nanotubes have shown that diamond nanowires are energetically and mechanically viable structures, reproducibly synthesizing the crystalline diamond nanowires has remained challenging. We present a comprehensive, up-to-date review of diamond nanowires, including a discussion of their synthesis along with their structures, properties, and applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, M.; Mauro, J.C.

    2012-01-01

    boroaluminosilicate glasses from peralkaline to peraluminous compositions by substituting Al2O3 for SiO2. Our results reveal a pronounced change in all the measured physical properties (density, elastic moduli, hardness, glass transition temperature, and liquid fragility) around [Al2O3]–[Na2O]=0. The structural...... origin of this change is elucidated through nuclear magnetic resonance analyses and topological considerations. Furthermore, we find that addition of 1 mol% Fe2O3 exerts a complicated impact on the measured properties....

  11. Structure-Property Relationships in Polycyanurate / Graphene Networks

    Science.gov (United States)

    2015-12-12

    AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NO. Air Force Research Laboratory (AFMC) AFRL/RQRP 10 E. Saturn Blvd. Edwards AFB, CA 93524-7680...RQR 11. SPONSOR/MONITOR’S REPORT 5 Pollux Drive NUMBER(S) Edwards AFB, CA 93524-7048 AFRL-RQ-ED-TP-2015-422 12. DISTRIBUTION / AVAILABILITY...Polycyanurate / Graphene Networks Andrew J. Guenthner,1 Josiah T. Reams,2 Kevin R. Lamison,2 Gregory R. Yandek,1 David D. Swanson,1 Joseph M. Mabry1

  12. Structure Property Relationships in Imidazole-based Deep Eutectic Mixtures

    Science.gov (United States)

    Terheggen, Logan; Cosby, Tyler; Sangoro, Joshua

    2015-03-01

    Deep eutectic mixtures of levulinic acid with a systematic series of imidazoles are measured by broadband dielectric spectroscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy to investigate the impact of steric interactions on charge transport and structural dynamics. An enhancement of dc conductivity is found in each of the imidazoles upon the addition of levulinic acid. However, the extent of increase is dependent upon the alkyl substitution on the imidazole ring. These results highlight the importance of molecular structure on hydrogen bonding and charge transport in deep eutectic mixtures.

  13. Quantitative structure-activity relationship (QSAR) for insecticides: development of predictive in vivo insecticide activity models.

    Science.gov (United States)

    Naik, P K; Singh, T; Singh, H

    2009-07-01

    Quantitative structure-activity relationship (QSAR) analyses were performed independently on data sets belonging to two groups of insecticides, namely the organophosphates and carbamates. Several types of descriptors including topological, spatial, thermodynamic, information content, lead likeness and E-state indices were used to derive quantitative relationships between insecticide activities and structural properties of chemicals. A systematic search approach based on missing value, zero value, simple correlation and multi-collinearity tests as well as the use of a genetic algorithm allowed the optimal selection of the descriptors used to generate the models. The QSAR models developed for both organophosphate and carbamate groups revealed good predictability with r(2) values of 0.949 and 0.838 as well as [image omitted] values of 0.890 and 0.765, respectively. In addition, a linear correlation was observed between the predicted and experimental LD(50) values for the test set data with r(2) of 0.871 and 0.788 for both the organophosphate and carbamate groups, indicating that the prediction accuracy of the QSAR models was acceptable. The models were also tested successfully from external validation criteria. QSAR models developed in this study should help further design of novel potent insecticides.

  14. Development and Structure/Property Relationship of New Electron Accepting Polymers Based on Thieno[2',3':4,5]pyrido[2,3- g ]thieno[3,2- c ]quinoline-4,10-dione for All-Polymer Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, In Hwan; Zhao, Donglin; Jang, Jaeyoung; Chen, Wei; Landry, Erik S.; Lu, Luyao; Talapin, Dmitri V.; Yu, Luping

    2015-09-08

    Several electron accepting polymers having weak accepting–strong accepting (WA-SA) and strong accepting–strong accepting (SA-SA) monomer alternation were synthesized for studies of structure/property relationship in all-polymer solar cells. Two kinds of cyclic amide monomers, 4,10-bis(2-butyloctyl)-thieno[2',3':5,6]pyrido[3,4-g]thieno-[3,2-c]isoquinoline-5,11-dione (TPTI) and 5,11-bis(2-butyloctyl)-thieno[2',3':4,5]pyrido[2,3-g]thieno[3,2-c]quinoline-4,10-dione (TPTQ), were synthesized as weak accepting monomers (WA). Difluorinated TPTQ (FTPTQ) and well-known perylene diimide (PDI) monomers were synthesized as strong electron accepting monomers (SA). By using 1-chloronaphthalene (CN) as a cosolvent, the morphology of the polymer blended films can be finely tuned to achieve better ordering toward face-on mode and favorable phase separation between electron donor and acceptor, resulting in significant enhancement of short circuit current (Jsc) and fill factor (FF). The fluorination in the TPTQ unit reduced the dipole moment of the D–A complex and gave a negative effect on a polymer system. PFP showed worse electron accepting property with lower electron mobility than PQP. It is reasoned that the internal polarization plays an important role in the design of electron accepting polymers. As a result, PQP having TPTQ monomer exhibited the best photovoltaic performance with power conversion efficiency (PCE) of 3.52% (Voc = 0.71 V, Jsc = 8.57 mA/cm2, FF = 0.58) at a weight ratio of PTB7-Th:PQP = 1:1, under AM 1.5G.

  15. Development and Structure/Property Relationship of New Electron Accepting Polymers Based on Thieno[2',3':4,5]pyrido[2,3- g ]thieno[3,2- c ]quinoline-4,10-dione for All-Polymer Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, In Hwan; Zhao, Donglin; Jang, Jaeyoung; Chen, Wei; Landry, Erik S.; Lu, Luyao; Talapin, Dmitri V.; Yu, Luping

    2015-09-08

    Several electron accepting polymers having weak accepting–strong accepting (WA-SA) and strong accepting–strong accepting (SA-SA) monomer alternation were synthesized for studies of structure/property relationship in all-polymer solar cells. Two kinds of cyclic amide monomers, 4,10-bis(2-butyloctyl)-thieno[2',3':5,6]pyrido[3,4-g]thieno-[3,2-c]isoquinoline-5,11-dione (TPTI) and 5,11-bis(2-butyloctyl)-thieno[2',3':4,5]pyrido[2,3-g]thieno[3,2-c]quinoline-4,10-dione (TPTQ), were synthesized as weak accepting monomers (WA). Difluorinated TPTQ (FTPTQ) and well-known perylene diimide (PDI) monomers were synthesized as strong electron accepting monomers (SA). By using 1-chloronaphthalene (CN) as a cosolvent, the morphology of the polymer blended films can be finely tuned to achieve better ordering toward face-on mode and favorable phase separation between electron donor and acceptor, resulting in significant enhancement of short circuit current (Jsc) and fill factor (FF). The fluorination in the TPTQ unit reduced the dipole moment of the D–A complex and gave a negative effect on a polymer system. PFP showed worse electron accepting property with lower electron mobility than PQP. It is reasoned that the internal polarization plays an important role in the design of electron accepting polymers. As a result, PQP having TPTQ monomer exhibited the best photovoltaic performance with power conversion efficiency (PCE) of 3.52% (Voc = 0.71 V, Jsc = 8.57 mA/cm2, FF = 0.58) at a weight ratio of PTB7-Th:PQP = 1:1, under AM 1.5G.

  16. Formation and structural properties of multi-block copolymer vesicles

    Science.gov (United States)

    Wang, Rong; Ma, Shiying

    2014-03-01

    Due to the unique structure, vesicles have attracted considerable attention for their potential applications, such as gene and drug delivery, microcapsules, nanoreactors, cell membrane mimetic, synthetic organelles, etc. By using dissipative particle dynamics, we studied the self-assembly of amphiphilic multi-block copolymer. The phase diagram was constructed by varying the interaction parameters and the composition of the block copolymers. The results show that the vesicles are stable in a large region which is different from the diblock copolymer or triblock copolymer. The structural properties of vesicles can be controlled by varying the interaction parameters and the length of the hydrophobic block. The relationship between the hydrophilic and hydrophobic block length vs the aqueous cavity size and vesicle size are revealed. The copolymers with shorter hydrophobic blocks length or the higher hydrophilicity are more likely to form vesicles with larger aqueous cavity size and vesicle size as well as thinner wall thickness. However, the increase in hydrophobic-block length results to form vesicles with smaller aqueous cavity size and larger vesicle size. Acknowledgments. This work has been supported by NNSFC (No. 21074053) and NBRPC (No. 2010CB923303).

  17. A Relationship-Building Model for the Web Retail Marketplace.

    Science.gov (United States)

    Wang, Fang; Head, Milena; Archer, Norm

    2000-01-01

    Discusses the effects of the Web on marketing practices. Introduces the concept and theory of relationship marketing. The relationship network concept, which typically is only applied to the business-to-business market, is discussed within the business-to-consumer market, and a new relationship-building model for the Web marketplace is proposed.…

  18. Unveiling DNA structural properties of promoter regions of ...

    Indian Academy of Sciences (India)

    Aditya Kumar

    Unveiling DNA structural properties of promoter regions of prokaryotic transcriptome and their role in gene expression. Aditya Kumar. Assistant Professor. Molecular Biology & Biotechnology. Tezpur University. Tezpur – 784028, Assam ...

  19. Inclusion of Switching Behaviour into Relationship Marketing Model

    DEFF Research Database (Denmark)

    Alnaimi, Husam; Jones, Richard; Perkins, Helen

    2011-01-01

    Relationship marketing authors have attempted to develop distinct models suitable for investigating relationship marketing in different contexts. However, there is no agreement as yet about the antecedents that best capture the characteristics of the relational exchange that influences relationship...... marketing. Maintaining a long-term relationship with a customer is one of the fundamental factors determining the value that the customer provides to the company. A serious threat to achieving a long-term relationship is the customer’s switching behaviour. This study develops a theoretical model...... of relationship marketing, which includes customers’ switching behaviour (switchers and stayers), as a vital construct to understand the relationship development process between customers and service providers. Also, hypotheses to specify the association between the underlying models’ constructs were presented...

  20. Information retrieval models foundations and relationships

    CERN Document Server

    Roelleke, Thomas

    2013-01-01

    Information Retrieval (IR) models are a core component of IR research and IR systems. The past decade brought a consolidation of the family of IR models, which by 2000 consisted of relatively isolated views on TF-IDF (Term-Frequency times Inverse-Document-Frequency) as the weighting scheme in the vector-space model (VSM), the probabilistic relevance framework (PRF), the binary independence retrieval (BIR) model, BM25 (Best-Match Version 25, the main instantiation of the PRF/BIR), and language modelling (LM). Also, the early 2000s saw the arrival of divergence from randomness (DFR).Regarding in

  1. Stochasticity in materials structure, properties, and processing—A review

    Science.gov (United States)

    Hull, Robert; Keblinski, Pawel; Lewis, Dan; Maniatty, Antoinette; Meunier, Vincent; Oberai, Assad A.; Picu, Catalin R.; Samuel, Johnson; Shephard, Mark S.; Tomozawa, Minoru; Vashishth, Deepak; Zhang, Shengbai

    2018-03-01

    We review the concept of stochasticity—i.e., unpredictable or uncontrolled fluctuations in structure, chemistry, or kinetic processes—in materials. We first define six broad classes of stochasticity: equilibrium (thermodynamic) fluctuations; structural/compositional fluctuations; kinetic fluctuations; frustration and degeneracy; imprecision in measurements; and stochasticity in modeling and simulation. In this review, we focus on the first four classes that are inherent to materials phenomena. We next develop a mathematical framework for describing materials stochasticity and then show how it can be broadly applied to these four materials-related stochastic classes. In subsequent sections, we describe structural and compositional fluctuations at small length scales that modify material properties and behavior at larger length scales; systems with engineered fluctuations, concentrating primarily on composite materials; systems in which stochasticity is developed through nucleation and kinetic phenomena; and configurations in which constraints in a given system prevent it from attaining its ground state and cause it to attain several, equally likely (degenerate) states. We next describe how stochasticity in these processes results in variations in physical properties and how these variations are then accentuated by—or amplify—stochasticity in processing and manufacturing procedures. In summary, the origins of materials stochasticity, the degree to which it can be predicted and/or controlled, and the possibility of using stochastic descriptions of materials structure, properties, and processing as a new degree of freedom in materials design are described.

  2. Thermodynamic and structural properties in complexing media

    International Nuclear Information System (INIS)

    Di Giandomenico, M.V.

    2007-10-01

    Protactinium is experiencing a renewal of interest in the frame of long-term energy production. Modelling the behaviour of this element in the geosphere requires thermodynamic and structural data relevant to environmental conditions. Now deep clayey formation are considered for the disposal of radioactive waste and high values of natural sulphate contents have been determined in pore water in equilibrium with clay surface. Because of its tendency to polymerisation, hydrolysis and sorption on all solid supports, the equilibria constants relative to monomer species were determined at tracer scale (ca. 10 - 12 M) with 233 Pa. The complexation constants of Pa(V) and sulphate ions were calculated starting from a systematic study of the apparent distribution coefficient D in the system TTA/Toluene/H 2 O/Na 2 SO 4 /HClO 4 /NaClO 4 and as a function of ionic strength, temperature, free sulphate, protons and chelatant concentration. First of all, the interaction between free species H + , SO 4 - , Na + leads to the formation of HSO 4 - and NaSO 4 - , for which concentrations depend upon the related thermodynamic constants. For this purpose a computer code was developed in order to determine all free species concentration. This iterative code takes into account the influence of temperature and ionic strength (SIT modelling) on thermodynamic constants. The direct measure of Pa(V) in the organic and aqueous phase by g-spectrometry had conducted to estimate the apparent distribution coefficient D as function of free sulphate ions. Complexation constants have been determined after a mathematical treatment of D. The extrapolation of these constants at zero ionic strength have been realized by SIT modelling at different temperatures. Besides, enthalpy and entropy values were calculated. Parallelly, the structural study of Pa(V) was performed using 231 Pa. XANES and EXAFS spectra show unambiguously the absence of the trans di-oxo bond that characterizes the other early actinide

  3. Structural Properties and Phonon dispertion of NACl

    Directory of Open Access Journals (Sweden)

    R. Khoda-Bakhsh

    2001-06-01

    Full Text Available   Although many phenomena in condensed matter Physics can be understood on the basis of a model, there are also considerable number of physical properties of solid which can not be explained except in the framework of lattice dynamics.   We have calculated the phonon frequencies of Na Cl, using an approach which is a combination of frozen phonon and force constants methods in the framework of density functional pseudopotential theory. The dispersion relation curves, were calculated along symmetry direction Δ,  Σ  and  Ù. We also calculated Grunesein parameters for all modes at X and L points in Brillion zone. The calcutions are made in the framework of density functional and pseudopotential theory, using super cell method, with the valence orbitals expanded in plane waves.

  4. modelling relationship between rainfall variability and yields

    African Journals Online (AJOL)

    yield models should be used for planning and forecasting the yield of millet and sorghum in the study area. Key words: modelling, rainfall, yields, millet, sorghum. INTRODUCTION. Meteorological variables, such as rainfall parameters, temperature, sunshine hours, relative humidity, and wind velocity and soil moisture are.

  5. Structure Property Studies for Additively Manufactured Parts

    Energy Technology Data Exchange (ETDEWEB)

    Milenski, Helen M [Univ. of Mexico, Los Alamos, NM (United States); Schmalzer, Andrew Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kelly, Daniel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-17

    Since the invention of modern Additive Manufacturing (AM) processes engineers and designers have worked hard to capitalize on the unique building capabilities that AM allows. By being able to customize the interior fill of parts it is now possible to design components with a controlled density and customized internal structure. The creation of new polymers and polymer composites allow for even greater control over the mechanical properties of AM parts. One of the key reasons to explore AM, is to bring about a new paradigm in part design, where materials can be strategically optimized in a way that conventional subtractive methods cannot achieve. The two processes investigated in my research were the Fused Deposition Modeling (FDM) process and the Direct Ink Write (DIW) process. The objectives of the research were to determine the impact of in-fill density and morphology on the mechanical properties of FDM parts, and to determine if DIW printed samples could be produced where the filament diameter was varied while the overall density remained constant.

  6. Structural properties of carbon nanotubes derived from 13C NMR

    KAUST Repository

    Abou-Hamad, E.

    2011-10-10

    We present a detailed experimental and theoretical study on how structural properties of carbon nanotubes can be derived from 13C NMR investigations. Magic angle spinning solid state NMR experiments have been performed on single- and multiwalled carbon nanotubes with diameters in the range from 0.7 to 100 nm and with number of walls from 1 to 90. We provide models on how diameter and the number of nanotube walls influence NMR linewidth and line position. Both models are supported by theoretical calculations. Increasing the diameter D, from the smallest investigated nanotube, which in our study corresponds to the inner nanotube of a double-walled tube to the largest studied diameter, corresponding to large multiwalled nanotubes, leads to a 23.5 ppm diamagnetic shift of the isotropic NMR line position δ. We show that the isotropic line follows the relation δ = 18.3/D + 102.5 ppm, where D is the diameter of the tube and NMR line position δ is relative to tetramethylsilane. The relation asymptotically tends to approach the line position expected in graphene. A characteristic broadening of the line shape is observed with the increasing number of walls. This feature can be rationalized by an isotropic shift distribution originating from different diamagnetic shielding of the encapsulated nanotubes together with a heterogeneity of the samples. Based on our results, NMR is shown to be a nondestructive spectroscopic method that can be used as a complementary method to, for example, transmission electron microscopy to obtain structural information for carbon nanotubes, especially bulk samples.

  7. Models of Shared Leadership: Evolving Structures and Relationships.

    Science.gov (United States)

    Hallinger, Philip; Richardson, Don

    1988-01-01

    Explores potential changes in the power relationships among teachers and principals. Describes and analyzes the following models of teacher decision-making: (1) Instructional Leadership Teams; (2) Principals' Advisory Councils; (3) School Improvement Teams; and (4) Lead Teacher Committees. (FMW)

  8. Personality, relationship conflict, and teamwork-related mental models

    NARCIS (Netherlands)

    Vîrgă, D.; Curseu, P.L.; Maricuţoiu, L.; Sava, S.A.; Macsinga, I.; Măgurean, S.

    2014-01-01

    This study seeks to explore whether neuroticism, agreeableness, and conscientiousness moderate the influence of relationship conflict experienced in groups on changes in group members' evaluative cognitions related to teamwork quality (teamwork-related mental models). Data from 216 students, nested

  9. Computational models for structure-hydrophobicity relationships of 4-carboxyl-2,6-dinitrophenyl azo hydroxynaphthalenes.

    Science.gov (United States)

    Idowu, Olakunle S; Adegoke, Olajire A; Idowu, Abiola; Olaniyi, Ajibola A

    2007-01-01

    Some phenyl azo hydroxynaphthalene dyes (e.g., sunset yellow) are certified as approved colorants for food, cosmetics, and drug formulations. The hydrophobicity of 4 newly synthesized azo dyes of the phenyl azo hydroxynaphthalene class was investigated, as a training set, with the goal of developing models for quantitative structure-property relationships (QSPR). Retention behavior of the molecules reversed-phase thin-layer chromatography (RPTLC) was investigated using liquid paraffin-coated silica gel as the stationary phase. Mobile phases consisted of aqueous mixtures of methanol, acetone, and dimethylformamide (DMF). Basic hydrophobicity parameter (Rmw), specific hydrophobic surface area (S), and isocratic chromatographic hydrophobicity index (phio) were computed from the chromatographic data. The hydrophobicity index (Rm) decreased linearly with increasing concentration of organic modifiers. Extrapolated Rmw values obtained by using DMF and acetone differ significantly from the value obtained by using methanol as organic modifier [P dyes and may also play useful roles in computer-assisted molecular discovery of nontoxic azo dyes.

  10. Inclusion of Switching Behaviour into Relationship Marketing Model

    DEFF Research Database (Denmark)

    Alnaimi, Husam; Jones, Richard; Perkins, Helen

    2011-01-01

    marketing. Maintaining a long-term relationship with a customer is one of the fundamental factors determining the value that the customer provides to the company. A serious threat to achieving a long-term relationship is the customer’s switching behaviour. This study develops a theoretical model...... of relationship marketing, which includes customers’ switching behaviour (switchers and stayers), as a vital construct to understand the relationship development process between customers and service providers. Also, hypotheses to specify the association between the underlying models’ constructs were presented...

  11. Relationship Management: Towards a Holistic model

    DEFF Research Database (Denmark)

    Andersen, Poul Houman

    2006-01-01

     This contribution provides a ground plan for managing the networked enterprise as a central aspect in 21st century organizations. It builds upon and synthesizes parts of the literature, but provides novel insights from this synthesis as well, using a model, that links three generic network...... management tasks with three levels of management, identifying 9 focus areas. Rather than distinguishing between the management of external and internal resources, integration of external and internal resources are in focus, meaning that all managerial tasks hold consequences both internally and externally...

  12. Structural Properties and Complexity of a New Network Class: Collatz Step Graphs

    Science.gov (United States)

    Emmert-Streib, Frank

    2013-01-01

    In this paper, we introduce a biologically inspired model to generate complex networks. In contrast to many other construction procedures for growing networks introduced so far, our method generates networks from one-dimensional symbol sequences that are related to the so called Collatz problem from number theory. The major purpose of the present paper is, first, to derive a symbol sequence from the Collatz problem, we call the step sequence, and investigate its structural properties. Second, we introduce a construction procedure for growing networks that is based on these step sequences. Third, we investigate the structural properties of this new network class including their finite scaling and asymptotic behavior of their complexity, average shortest path lengths and clustering coefficients. Interestingly, in contrast to many other network models including the small-world network from Watts & Strogatz, we find that CS graphs become ‘smaller’ with an increasing size. PMID:23431377

  13. Major dimensions in food-web structure properties

    NARCIS (Netherlands)

    Vermaat, J.E.; Dunne, J. A.; Gilbert, A.J.

    2009-01-01

    The covariance among a range of 20 network structural properties of food webs plus net primary productivity was assessed for 14 published food webs using principal components analysis. Three primary components explained 84% of the variability in the data sets, suggesting substantial covariance among

  14. Comparative study of the physiochemical and structural properties of ...

    African Journals Online (AJOL)

    A comparative analysis of some physiochemical and structural parameters of brown (mature) and green (immature) coconut fibre as adsorbents was studied. The physiochemical and structural properties evaluated were surface area, moisture content, pH, bulk density, pore volume, porosity, ash content, tortuocity and metal ...

  15. Structural Properties of Dwelling and Thermal Comfort in Tropical ...

    African Journals Online (AJOL)

    The structural properties of dwelling units, in particular “window types” in 1, 250 apartments and their indoor temperature levels were collected. One hypothesis was formulated: (HO) There is no significant variation in effective temperature index and thus thermal comfort between dwellings built with wooden windows and ...

  16. Ab-initio theoretical predictions of structure properties of semiconductors

    International Nuclear Information System (INIS)

    Rodriguez, C.O.; Peltzer y Blanca, E.L.; Cappannini, O.M.

    1983-01-01

    In this paper, calculations of the total energies and related structural properties of Si, GaP and C are presented showing good agreement with experimental values. The total energy is calculated within the local-density functional formalism using first principles non-local pseudopotentials. (A.C.A.S.) [pt

  17. Structural properties of reflected Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang; Mandjes, Michel

    This paper considers a number of structural properties of reflected Lévy processes, where both one-sided reflection (at 0) and two-sided reflection (at both 0 and K > 0) are examined. With Vt being the position of the reflected process at time t, we focus on the analysis of ζ(t) := EVt and ξ(t) :...

  18. Structural properties of hydrogen isotopes in solid phase in the context of inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    Guerrero Carlo

    2013-11-01

    Full Text Available Quality of Deuterium-Tritium capsules is a critical aspect in Inertial Confinement Fusion. In this work, we present a Quantum Molecular Dynamics methodology able to model hydrogen isotopes and their structural molecular organisation at extreme pressures and cryogenic temperatures (< 15 K. Our study sets up the basis for a future analysis on the mechanical and structural properties of DT-ice in inertial confinement fusion (ICF target manufacturing conditions.

  19. Relationships between water table and model simulated ET

    Science.gov (United States)

    Prem B. Parajuli; Gretchen F. Sassenrath; Ying Ouyang

    2013-01-01

    This research was conducted to develop relationships among evapotranspiration (ET), percolation (PERC), groundwater discharge to the stream (GWQ), and water table fluctuations through a modeling approach. The Soil and Water Assessment Tool (SWAT) hydrologic and crop models were applied in the Big Sunflower River watershed (BSRW; 7660 km2) within the Yazoo River Basin...

  20. [RELATIONSHIP BETWEEN JUNIOR AND SENIOR DOCTORS: A BUBERIAN MODEL].

    Science.gov (United States)

    Pougnet, Richard; Pougnet, Laurence

    2016-01-01

    Doctors in training work in services under the supervision of senior doctors. These professional relationships may lead to frustrations, or ill-being at work. Indeed doctors are often very busy with care and can hardly communicate. The purpose of this article is to propose ways to think in its ethical dimension this relationship, by learning from Martin Buber's ideas. He thought a philosophy of relationship in two word pairs: I-Thou and I-It. This thought can be useful in the context of the médical relationship and mentorship. Indeed we can see our colleague as a person or only as a caregiver. We offer a relationship model according to buberian thought, between junior and senior doctor caring about the same patients.

  1. Structure-property investigations of conjugated thiophenes fused onto a dehydro[14]annulene scaffold.

    Science.gov (United States)

    O'Connor, Matthew J; Yelle, Robert B; Zakharov, Lev N; Haley, Michael M

    2008-06-20

    A series of 12 thieno-fused macrocycles based on the dehydro[14]annulene framework have been prepared. Studies have focused on the optical and electronic properties of the dehydrobenzothieno[14]annulenes (DBTAs) and dehydrothieno[14]annulenes (DTAs) utilizing NMR spectroscopy, UV-vis spectrophotometry, electrochemistry, and DFT computations. X-ray crystal structures were also obtained for two of the macrocycles. The structure-property relationships were found to vary significantly based on the relative orientation of the thiophenes. The stability, properties, and reactivity of these macrocycles were found to be more typical of dehydroannulenes rather than oligothiophenes.

  2. Personality, Relationship Conflict, and Teamwork-Related Mental Models

    Science.gov (United States)

    Vîrgă, Delia; CurŞeu, Petru Lucian; Maricuţoiu, Laurenţiu; Sava, Florin A.; Macsinga, Irina; Măgurean, Silvia

    2014-01-01

    This study seeks to explore whether neuroticism, agreeableness, and conscientiousness moderate the influence of relationship conflict experienced in groups on changes in group members' evaluative cognitions related to teamwork quality (teamwork-related mental models). Data from 216 students, nested in 48 groups were analyzed using a multilevel modeling approach. Our results show that the experience of relationship conflict leads to a negative shift from the pre-task to the post-task teamwork-related mental models. Moreover, the results indicate that conscientiousness buffered the negative association between relationship conflict and the change in teamwork-related mental models. Our results did not support the hypothesized moderating effect of agreeableness and show that the detrimental effect of relationship conflict on the shift in teamwork-related mental models is accentuated for group members scoring low rather than high on neuroticism. These findings open new research venues for exploring the association between personality, coping styles and change in teamwork-related mental models. PMID:25372143

  3. Personality, relationship conflict, and teamwork-related mental models.

    Science.gov (United States)

    Vîrgă, Delia; Curşeu, Petru Lucian; CurŞeu, Petru Lucian; Maricuţoiu, Laurenţiu; Sava, Florin A; Macsinga, Irina; Măgurean, Silvia

    2014-01-01

    This study seeks to explore whether neuroticism, agreeableness, and conscientiousness moderate the influence of relationship conflict experienced in groups on changes in group members' evaluative cognitions related to teamwork quality (teamwork-related mental models). Data from 216 students, nested in 48 groups were analyzed using a multilevel modeling approach. Our results show that the experience of relationship conflict leads to a negative shift from the pre-task to the post-task teamwork-related mental models. Moreover, the results indicate that conscientiousness buffered the negative association between relationship conflict and the change in teamwork-related mental models. Our results did not support the hypothesized moderating effect of agreeableness and show that the detrimental effect of relationship conflict on the shift in teamwork-related mental models is accentuated for group members scoring low rather than high on neuroticism. These findings open new research venues for exploring the association between personality, coping styles and change in teamwork-related mental models.

  4. Liposomes: structure, properties and methods of curative administration in organism

    Directory of Open Access Journals (Sweden)

    M. A. Kisyakova

    2010-07-01

    Full Text Available A review of data from scientific sources, devoted to problems of liposomes’ structure, properties and processes of formation was made. Advantages of liposomes used for medical purposes are shown. Methods of liposomes administration in an organism are characterised. Data on mechanisms of interaction between liposomes and cells, peculiarities of liposomes’ lipids composition and dependence of its tropism to definite organs and tissues are generalised.

  5. Event-Entity-Relationship Modeling in Data Warehouse Environments

    DEFF Research Database (Denmark)

    Bækgaard, Lars

    We use the event-entity-relationship model (EVER) to illustrate the use of entity-based modeling languages for conceptual schema design in data warehouse environments. EVER is a general-purpose information modeling language that supports the specification of both general schema structures and multi......-dimensional schemes that are customized to serve specific information needs. EVER is based on an event concept that is very well suited for multi-dimensional modeling because measurement data often represent events in multi-dimensional databases...

  6. Modeling the Relationships between Subdimensions of Environmental Literacy

    Science.gov (United States)

    Genc, Murat; Akilli, Mustafa

    2016-01-01

    The aim of this study is to demonstrate the relationships between subdimensions of environmental literacy using Structural Equation Modeling (SEM). The study was conducted by the analysis of students' answers to questionnaires data using SEM. Initially, Kaiser-Meyer-Olkin and Bartlett's tests were done to test appropriateness of subdimensions to…

  7. Simulating pattern-process relationships to validate landscape genetic models

    Science.gov (United States)

    A. J. Shirk; S. A. Cushman; E. L. Landguth

    2012-01-01

    Landscapes may resist gene flow and thereby give rise to a pattern of genetic isolation within a population. The mechanism by which a landscape resists gene flow can be inferred by evaluating the relationship between landscape models and an observed pattern of genetic isolation. This approach risks false inferences because researchers can never feasibly test all...

  8. Modeling time-lagged reciprocal psychological empowerment-performance relationships.

    Science.gov (United States)

    Maynard, M Travis; Luciano, Margaret M; D'Innocenzo, Lauren; Mathieu, John E; Dean, Matthew D

    2014-11-01

    Employee psychological empowerment is widely accepted as a means for organizations to compete in increasingly dynamic environments. Previous empirical research and meta-analyses have demonstrated that employee psychological empowerment is positively related to several attitudinal and behavioral outcomes including job performance. While this research positions psychological empowerment as an antecedent influencing such outcomes, a close examination of the literature reveals that this relationship is primarily based on cross-sectional research. Notably, evidence supporting the presumed benefits of empowerment has failed to account for potential reciprocal relationships and endogeneity effects. Accordingly, using a multiwave, time-lagged design, we model reciprocal relationships between psychological empowerment and job performance using a sample of 441 nurses from 5 hospitals. Incorporating temporal effects in a staggered research design and using structural equation modeling techniques, our findings provide support for the conventional positive correlation between empowerment and subsequent performance. Moreover, accounting for the temporal stability of variables over time, we found support for empowerment levels as positive influences on subsequent changes in performance. Finally, we also found support for the reciprocal relationship, as performance levels were shown to relate positively to changes in empowerment over time. Theoretical and practical implications of the reciprocal psychological empowerment-performance relationships are discussed. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  9. Dyadic Empathy, Dyadic Coping, and Relationship Satisfaction: A Dyadic Model

    Directory of Open Access Journals (Sweden)

    Christine Levesque

    2014-02-01

    Full Text Available The purpose of the present study was to investigate a theoretical model specifying the direct and indirect associations between dyadic empathy, dyadic coping, and relationship satisfaction in a sample of 187 heterosexual couples. Dyadic and structural aspects of mediation were tested using the Actor-Partner Interdependence Model. Results revealed that greater levels of an individual’s own propensity for dyadic empathy (i.e., one’s ability to experience empathic concern and perspective-taking significantly predicted greater levels of an individual’s own dyadic coping strategies among both male and female participants. Moreover, increased levels of an individual’s own dyadic coping strategies significantly predicted a similar greater degree of an individual’s own relationship satisfaction. Furthermore, results also provide support for the possible mediating role that an individual’s own dyadic coping strategies may hold in explaining the links between an individual’s own empathic concern and an individual’s own relationship satisfaction among male participants. With regard to the dyadic components of the study’s model, findings indicated that perspective-taking among males significantly improve their female partners’ propensity to employ positive dyadic coping strategies. Moreover, empathic concern among female participants was found to improve their male partners’ dyadic coping strategies. Findings suggest the potential utility of examining dyadic coping as a means to expand clinical and empirical insights regarding the links between dyadic empathy and relationship satisfaction.

  10. Floor response spectra of buildings with uncertain structural properties

    International Nuclear Information System (INIS)

    Chen, P.C.

    1975-01-01

    All Category I equipment, such as reactors, vessels, and major piping systems of nuclear power plants, is required to withstand earthquake loadings in order to minimize risk of seismic damage. The equipment is designed by using response spectra of the floor on which the equipment is mounted. The floor response spectra are constructed usually from the floor response time histories which are obtained through a deterministic dynamic analysis. This analysis assumes that all structural parameters, such as mass, stiffness, and damping have been calculated precisely, and that the earthquakes are known. However, structural parameters are usually difficult to determine precisely if the structures are massive and/or irregular, such as nuclear containments and its internal structures with foundation soil incorporated into the analysis. Faced with these uncertainties, it has been the practice to broaden the floor response spectra peaks by +-10 percent of the peak frequencies on the basis of conservatism. This approach is based on engineering judgement and does not have an analytical basis to provide a sufficient level of confidence in using these spectra for equipment design. To insure reliable design, it is necessary to know structural response variations due to variations in structural properties. This consideration leads to the treatment of structural properties as random variables and the use of probabilistic methods to predict structural response more accurately. New results on floor response spectra of buildings with uncertain structural properties obtained by determining the probabilistic dynamic response from the deterministic dynamic response and its standard deviation are presented. The resulting probabilistic floor response spectra are compared with those obtained deterministically, and are shown to provide a more reliable method for determining seismic forces

  11. Structural properties of amorphous silicon produced by electron irradiation

    International Nuclear Information System (INIS)

    Yamasaki, J.; Takeda, S.

    1999-01-01

    The structural properties of the amorphous Si (a-Si), which was created from crystalline silicon by 2 MeV electron irradiation at low temperatures about 25 K, are examined in detail by means of transmission electron microscopy and transmission electron diffraction. The peak positions in the radial distribution function (RDF) of the a-Si correspond well to those of a-Si fabricated by other techniques. The electron-irradiation-induced a-Si returns to crystalline Si after annealing at 550 C

  12. Structural properties of recursively partitionable graphs with connectivity 2

    DEFF Research Database (Denmark)

    Baudon, Olivier; Bensmail, Julien; Foucaud, Florent

    2017-01-01

    , namely the ones of being online arbitrarily partitionable and recursively arbitrarily partitionable (OL-AP and R-AP for short, respectively), in which the subgraphs induced by a partition of G must not only be con-nected but also ful_l additional conditions. In this paper, we point out some structural...... properties of OL-AP and R-AP graphs with connectivity 2. In particular, we show that deleting a cut pair of these graphs results in a graph with a bounded number of components, some of whom have a small number of vertices. We obtain these results by studying a simple class of 2-connected graphs called...

  13. Mechanical and structural properties of sputtered Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Senthil Kumar, M.; Boeni, P.; Tixier, S.; Clemens, D.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    Ni/Ti bilayers have been prepared by dc-magnetron sputtering in order to study their mechanical and structural properties. A remarkable reduction of stress is observed when the Ni layers are sputtered reactively in argon with a high partial pressure of air. The high angle x-ray diffraction studies show a tendency towards amorphisation of the Ni layers with increasing air flow. The low angle measurements indicate a substantial reduction of interdiffusion resulting in smoother interfaces with increasing air content. (author) 2 figs., 2 refs.

  14. Modeling and Querying Moving Objects with Social Relationships

    Directory of Open Access Journals (Sweden)

    Hengcai Zhang

    2016-07-01

    Full Text Available Current moving-object database (MOD systems focus on management of movement data, but pay less attention to modelling social relationships between moving objects and spatial-temporal trajectories in an integrated manner. This paper combines moving-object database and social network systems and presents a novel data model called Geo-Social-Moving (GSM that enables the unified management of trajectories, underlying geographical space and social relationships for mass moving objects. A bulk of user-defined data types and corresponding operators are also proposed to facilitate geo-social queries on moving objects. An implementation framework for the GSM model is proposed, and a prototype system based on native Neo4J is then developed with two real-world data sets from the location-based social network systems. Compared with solutions based on traditional extended relational database management systems characterized by time-consuming table join operations, the proposed GSM model characterized by graph traversal is argued to be more powerful in representing mass moving objects with social relationships, and more efficient and stable for geo-social querying.

  15. Exploring the relationship between sustainability and project success - conceptual model and expected relationships

    Directory of Open Access Journals (Sweden)

    Gilbert Silvius

    2016-01-01

    Full Text Available Sustainability is one of the most important challenges of our time. Companies are integrating sustainability in their marketing, communication and their actions. Sustainability has more recently also been linked to project management. The logic behind this link is that sustainability needs change and projects are realizing change. Several studies explored how the concept of sustainability impact project management. The research project reported in this paper elaborates on these works by studying how sustainability affects project success. Project managers, logically, strive for project success and considering sustainability may influence this success. Based upon a review of relevant literature, the paper develops a conceptual model that provides a more detailed understanding of how considering different dimensions of sustainability may affect the individual criteria of project success. The study also provides a conceptual mapping of the different relationships between dimensions of sustainability and criteria of project success. This mapping shows that the most positive relationships are expected for the relationship between sustainability and the success criteria stakeholder satisfaction, future readiness and controlled project execution. The expected relationship between considering sustainability and completing the project on schedule and within budget is uncertain.

  16. Applying quantitative structure-activity relationship (QSAR) methodology for modeling postmortem redistribution of benzodiazepines and tricyclic antidepressants.

    Science.gov (United States)

    Giaginis, Constantinos; Tsantili-Kakoulidou, Anna; Theocharis, Stamatios

    2014-06-01

    Postmortem redistribution (PMR) constitutes a multifaceted process, which complicates the interpretation of drug concentrations by forensic toxicologists. The present study aimed to apply quantitative structure-activity relationship (QSAR) analysis for modeling PMR data of structurally related drugs, 10 benzodiazepines and 10 tricyclic antidepressants. For benzodiazepines, an adequate QSAR model was obtained (R(2) = 0.98, Q(2) = 0.88, RMSEE = 0.12), in which energy, ionization and molecular size exerted significant impact. For tricyclic antidepressants, an adequate QSAR model with slightly inferior statistics (R(2) = 0.95, Q(2) = 0.87, RMSEE = 0.29) was established after exclusion of maprotiline, in which energy parameters, basicity character and lipophilicity exerted significant contribution. Thus, QSAR analysis could be used as a complementary tool to provide an informative illustration of the contributing molecular, physicochemical and structural properties in PMR process. However, the complexity, non-static and time-dependent nature of PMR endpoints raises serious concerns whether QSAR methodology could predict the degree of redistribution, highlighting the need for animal-derived PMR data.

  17. [Relationship between two models of personality in old individuals].

    Science.gov (United States)

    Calvet, Benjamin; Bricaud, Magali; Clément, Jean-Pierre

    2014-12-01

    The relationships between the seven dimensions of the Cloninger psychobiological model and the five factors of the Costa and McCrae model were examined in 54 elderly subjects from the French general population. The dimensions of temperament (novelty seeking, harm avoidance, reward dependence) and character (determination, cooperation, transcendence) from the Cloninger's model were measured by the temperament and character inventory whereas the five factors of Costa and McCrae model (neuroticism, extraversion, openness to experience, agreeableness and conscientiousness) were evaluated using the NEO PI-R. Multiple regression analyses show that some dimensions of the temperament and character inventory predict some dimensions of the Big five and vice versa. Therefore we suggest that the Big five model could be related to brain monoaminergic activities.

  18. Relationship Marketing results: proposition of a cognitive mapping model

    Directory of Open Access Journals (Sweden)

    Iná Futino Barreto

    2015-12-01

    Full Text Available Objective - This research sought to develop a cognitive model that expresses how marketing professionals understand the relationship between the constructs that define relationship marketing (RM. It also tried to understand, using the obtained model, how objectives in this field are achieved. Design/methodology/approach – Through cognitive mapping, we traced 35 individual mental maps, highlighting how each respondent understands the interactions between RM elements. Based on the views of these individuals, we established an aggregate mental map. Theoretical foundation – The topic is based on a literature review that explores the RM concept and its main elements. Based on this review, we listed eleven main constructs. Findings – We established an aggregate mental map that represents the RM structural model. Model analysis identified that CLV is understood as the final result of RM. We also observed that the impact of most of the RM elements on CLV is brokered by loyalty. Personalization and quality, on the other hand, proved to be process input elements, and are the ones that most strongly impact others. Finally, we highlight that elements that punish customers are much less effective than elements that benefit them. Contributions - The model was able to insert core elements of RM, but absent from most formal models: CLV and customization. The analysis allowed us to understand the interactions between the RM elements and how the end result of RM (CLV is formed. This understanding improves knowledge on the subject and helps guide, assess and correct actions.

  19. Model Pengukuran Kinerja Customer Relationship Management dalam Industri Perbankan

    Directory of Open Access Journals (Sweden)

    Freddy Simbolon

    2014-05-01

    Full Text Available High competition in the banking industry requires the banking industry to properly manage relationships with customers, as it is known as Customer Relationship Management (CRM. CRM applications will become effective when supported by information technology. Investment in information technology is not a small investment, because the higher the information technology, the greater the value of the investment. This study aims to obtain a model of CRM performance measurement in the banking industry efficiently and effective. The method in this study uses descriptive analytical method, while the results obtained in this study is a CRM Scorecard. CRM Scorecard is one of the approach models that correctly measure the performance of CRM, which is based on information technology. Through CRM Scorecard approach, information technology investment in CRM is no longer seen as a cost center, but seen to be a profit center, because the company can manage customers efficiently and effectively in order to enhance shareholder value in the future.

  20. Incentive Model Based on Cooperative Relationship in Sustainable Construction Projects

    Directory of Open Access Journals (Sweden)

    Guangdong Wu

    2017-07-01

    Full Text Available Considering the cooperative relationship between owners and contractors in sustainable construction projects, as well as the synergistic effects created by cooperative behaviors, a cooperative incentive model was developed using game theory. The model was formulated and analyzed under both non-moral hazard and moral hazard situations. Then, a numerical simulation and example were proposed to verify the conclusions derived from the model. The results showed that the synergistic effect increases the input intensity of one party’s resource transfer into the increase of marginal utility of the other party, thus the owner and contractor are willing to enhance their levels of effort. One party’s optimal benefit allocation coefficient is positively affected by its own output efficiency, and negatively affected by the other party’s output efficiency. The effort level and expected benefits of the owner and contractor can be improved by enhancing the cooperative relationship between the two parties, as well as enhancing the net benefits of a sustainable construction project. The synergistic effect cannot lower the negative effect of moral hazard behaviors during the implementation of sustainable construction projects. Conversely, the higher levels of the cooperative relationship, the wider the gaps amongst the optimal values under both non-moral hazard and moral hazard situations for the levels of effort, expected benefits and net project benefits. Since few studies to date have emphasized the effects of cooperative relationship on sustainable construction projects, this study constructed a game-based incentive model to bridge the gaps. This study contributes significant theoretical and practical insights into the management of cooperation amongst stakeholders, and into the enhancement of the overall benefits of sustainable construction projects.

  1. Structural properties of the Chinese air transportation multilayer network

    International Nuclear Information System (INIS)

    Hong, Chen; Zhang, Jun; Cao, Xian-Bin; Du, Wen-Bo

    2016-01-01

    Highlights: • We investigate the structural properties of the Chinese air transportation multilayer network (ATMN). • We compare two main types of layers corresponding to major and low-cost airlines. • It is found that small-world property and rich-club effect of the Chinese ATMN are mainly caused by major airlines. - Abstract: Recently multilayer networks are attracting great attention because the properties of many real-world systems cannot be well understood without considering their different layers. In this paper, we investigate the structural properties of the Chinese air transportation multilayer network (ATMN) by progressively merging layers together, where each commercial airline (company) defines a layer. The results show that the high clustering coefficient, short characteristic path length and large collection of reachable destinations of the Chinese ATMN can only emerge when several layers are merged together. Moreover, we compare two main types of layers corresponding to major and low-cost airlines. It is found that the small-world property and the rich-club effect of the Chinese ATMN are mainly caused by those layers corresponding to major airlines. Our work will highlight a better understanding of the Chinese air transportation network.

  2. Selecting an optimal mixed products using grey relationship model

    Directory of Open Access Journals (Sweden)

    Farshad Faezy Razi

    2013-06-01

    Full Text Available This paper presents an integrated supplier selection and inventory management using grey relationship model (GRM as well as multi-objective decision making process. The proposed model of this paper first ranks different suppliers based on GRM technique and then determines the optimum level of inventory by considering different objectives. To show the implementation of the proposed model, we use some benchmark data presented by Talluri and Baker [Talluri, S., & Baker, R. C. (2002. A multi-phase mathematical programming approach for effective supply chain design. European Journal of Operational Research, 141(3, 544-558.]. The preliminary results indicate that the proposed model of this paper is capable of handling different criteria for supplier selection.

  3. The many relationships between the IBM and the Bohr model

    International Nuclear Information System (INIS)

    Rowe, D.J.; Thiamova, G.

    2005-01-01

    Relationships between the IBM-1 and the Bohr collective model are explored in which the states of the IBM in its various dynamical symmetry limits are identified with subsets of Bohr model states of corresponding dynamical symmetries. The maps of interest are ones which give the contractions of the IBM in the limit of large boson number. The known map from the IBM into the Bohr model gives a contraction appropriate for the U(5) dynamical symmetry limit. A new map is given consistent with a contraction of the O(6) dynamical symmetry of the IBM. This map gives an explicit identification of IBM states in an O(6)-bar O(5) basis with states of the Wilets-Jean model and makes it possible to benefit from the different but complementary perspectives of the two models. For example, it leads to explicit expressions for the matrix elements of an IBM O(6) irrep in terms of the known matrix elements of the corresponding Wilets-Jean model. The relationship also shows how to obtain the familiar rotor plus beta- and gamma-vibrational bands of the Bohr-Mottelson model, in the IBM, by the addition to an O(6) Hamiltonian of a scalar cubic in the quadrupole moment operators of the type considered recently by Van Isacker. The establishment of close relationships between the two models enables one to benefit from the different and complementary perspectives they afford. For example, recent developments of an algebraic version of the collective model has shown that the Bohr model has an SU(1,1)xO(5) dynamical group with representations ranging from those of a spherical vibrator to a beta-vibrational soft-gamma rotor of the Wilets-Jean limit and, with the addition of an interaction, to a rotor of the standard Bohr-Mottelson type with beta- and gamma-vibrational bands. A parallel range of results can now be obtained in the IBM, albeit with some differences, within the framework of an SU(1,1)xO(5) dynamical group

  4. The Relationship Between Resilience and Internet Addiction: A Multiple Mediation Model Through Peer Relationship and Depression.

    Science.gov (United States)

    Zhou, Pingyan; Zhang, Cai; Liu, Jian; Wang, Zhe

    2017-10-01

    Heavy use of the Internet may lead to profound academic problems in elementary students, such as poor grades, academic probation, and even expulsion from school. It is of great concern that Internet addiction problems in elementary school students have increased sharply in recent years. In this study, 58,756 elementary school students from the Henan province of China completed four questionnaires to explore the mechanisms of Internet addiction. The results showed that resilience was negatively correlated with Internet addiction. There were three mediational paths in the model: (a) the mediational path through peer relationship with an effect size of 50.0 percent, (b) the mediational path through depression with an effect size of 15.6 percent, (c) the mediational path through peer relationship and depression with an effect size of 13.7 percent. The total mediational effect size was 79.27 percent. The effect size through peer relationship was the strongest among the three mediation paths. The current findings suggest that resilience is a predictor of Internet addiction. Improving children's resilience (such as toughness, emotional control, and problem solving) can be an effective way to reduce Internet addiction behavior. The current findings provide useful information for early detection and intervention for Internet addiction.

  5. Modeling relationships between calving traits: a comparison between standard and recursive mixed models.

    Science.gov (United States)

    de Maturana, Evangelina López; de los Campos, Gustavo; Wu, Xiao-Lin; Gianola, Daniel; Weigel, Kent A; Rosa, Guilherme J M

    2010-01-25

    The use of structural equation models for the analysis of recursive and simultaneous relationships between phenotypes has become more popular recently. The aim of this paper is to illustrate how these models can be applied in animal breeding to achieve parameterizations of different levels of complexity and, more specifically, to model phenotypic recursion between three calving traits: gestation length (GL), calving difficulty (CD) and stillbirth (SB). All recursive models considered here postulate heterogeneous recursive relationships between GL and liabilities to CD and SB, and between liability to CD and liability to SB, depending on categories of GL phenotype. Four models were compared in terms of goodness of fit and predictive ability: 1) standard mixed model (SMM), a model with unstructured (co)variance matrices; 2) recursive mixed model 1 (RMM1), assuming that residual correlations are due to the recursive relationships between phenotypes; 3) RMM2, assuming that correlations between residuals and contemporary groups are due to recursive relationships between phenotypes; and 4) RMM3, postulating that the correlations between genetic effects, contemporary groups and residuals are due to recursive relationships between phenotypes. For all the RMM considered, the estimates of the structural coefficients were similar. Results revealed a nonlinear relationship between GL and the liabilities both to CD and to SB, and a linear relationship between the liabilities to CD and SB.Differences in terms of goodness of fit and predictive ability of the models considered were negligible, suggesting that RMM3 is plausible. The applications examined in this study suggest the plausibility of a nonlinear recursive effect from GL onto CD and SB. Also, the fact that the most restrictive model RMM3, which assumes that the only cause of correlation is phenotypic recursion, performs as well as the others indicates that the phenotypic recursion may be an important cause of the

  6. Theory of the structural properties of A-15 type materials

    Energy Technology Data Exchange (ETDEWEB)

    Gor' kov, L.P.; Dorokhov, O.N.

    1976-01-01

    The theory of the structural properties of the A-15 compounds is developed starting with a picture of linear chains of atoms of the transition elements. The twofold-degenerate electronic term is shifted and split when interchain transfer is taken into account. A fine structure of the electronic spectrum and the density of states are examined. The latter has two singularities at the Fermi level corresponding to an estimated variation of the composition by several percent. Among the samples showing the martensitic transformation, one of these singularities is supposed to be responsible for the peculiar properties observed, and a theory of the transformation from the cubic to the tetragonal phase is suggested. The temperature dependence of the phonon spectrum has been studied in detail. The theory explains the softening of the phonon modes at large wave vectors in some directions, and predicts features of the phonon spectrum whose observation could be crucial to the theory. 26 references.

  7. Structural properties of maize hybrids established by infrared spectra

    Directory of Open Access Journals (Sweden)

    Radenović Čedomir N.

    2015-01-01

    Full Text Available This paper discusses the application of the infrared (IR spectroscopy method for determination of structural properties of maize hybrid grains. The IR spectrum of maize grain has been registered in the following hybrids: ZP 341, ZP 434 and ZP 505. The existence of spectral bands varying in both number and intensity, as well as their shape, frequency and kinetics have been determined. They have been determined by valence oscillations and deformation oscillations of the following organic compounds: alkanes, alkenes, alkynes, amides, alcohols, ethers, carboxylic acids, esters and aldehydes and ketones, characteristic for biogenic compounds such as carbohydrates, proteins and lipids. In this way, possible changes in the grain structure of observed maize hybrids could be detected.

  8. Modeling of microstructure property relationships in titanium-aluminum-vanadium

    Science.gov (United States)

    Tiley, Jaimie Scott

    Fuzzy logic neural network models were developed to predict the room temperature tensile behavior of Ti-6Al-4V. This involved the development of a database relating microstructure to properties. This necessitated establishing heat treatment processes to develop microstructural features, mechanical testing of samples, creating rigorous stereology procedures, developing numerical models to predict mechanical behavior, and determining trends and inter-relationships relating microstructural features to mechanical properties. Microstructural features were developed using a Gleeble(TM) 1500 Thermal-mechanical simulator. Samples were obtained from mill annealed plate material and both alpha + beta forged and beta forged materials. A total of 72 samples were beta solutionized and heat treated using different heating and cooling conditions. Rigorous stereology procedures were developed to characterize the important microstructural features. The features included Widmanstatten alpha lath thickness, volume fraction of total alpha, volume fraction of Widmanstatten alpha, grain boundary alpha thickness, mean edge length, colony scale factor, and prior beta grain size factor. Chemical composition was also determined using standard chemical analysis and microscopy techniques. The samples were tested for yield strength, ultimate tensile strength, and elongation at room temperature. Results from the tests and the characterization were used to develop fuzzy logic neural network models to predict the mechanical behaviors and develop relationships between the microstructural features (using CubiCalc RTC(TM)). Results were compared to standard multi-variable regression models. The fuzzy logic neural network models were able to predict the yield, and ultimate tensile strength, within acceptable error ranges with a limited number of input data samples. The models also predicted the elongation values but with larger errors. Of particular importance, the models identified the importance of

  9. Relationship model and supporting activities of JIT, TQM and TPM

    Directory of Open Access Journals (Sweden)

    Nuttapon SaeTong

    2011-02-01

    Full Text Available This paper gives a relationship model and supporting activities of Just-in-time (JIT, Total Quality Management (TQM,and Total Productive Maintenance (TPM. By reviewing the concepts, 5S, Kaizen, preventive maintenance, Kanban, visualcontrol, Poka-Yoke, and Quality Control tools are the main supporting activities. Based on the analysis, 5S, preventive maintenance,and Kaizen are the foundation of the three concepts. QC tools are required activities for implementing TQM, whereasPoka-Yoke and visual control are necessary activities for implementing TPM. After successfully implementing TQM andTPM, Kanban is needed for JIT.

  10. The effect of mechanical drawing on optical and structural properties of nylon 6 fibres

    Science.gov (United States)

    El-Bakary, M. A.

    2007-09-01

    The Pluta polarizing double-refracting interference microscope was attached to a mechanical drawing device to study the effect of cold drawing on the optical and structural properties of nylon 6 fibres. The microscope was used in its two positions for determining the refractive indices and birefringence of fibres. Different applied stresses and strain rates were obtained using the mechanical-drawing device. The effect of the applied stresses on the optical and physical parameters was investigated. The resulting optical parameters were utilized to investigate the polarizability per unit volume, the optical orientation factor, the orientation angle and the average work per chain. The refractive index and birefringence profiles were measured. Relationships between the average work per chain and optical parameters at different strains rates were determined. An empirical formula was deduced for these fibres. Micro-interferograms are given for illustration.

  11. Electronic and structural properties of ultrathin tungsten nanowires and nanotubes by density functional theory calculation

    International Nuclear Information System (INIS)

    Sun, Shih-Jye; Lin, Ken-Huang; Li, Jia-Yun; Ju, Shin-Pon

    2014-01-01

    The simulated annealing basin-hopping method incorporating the penalty function was used to predict the lowest-energy structures for ultrathin tungsten nanowires and nanotubes of different sizes. These predicted structures indicate that tungsten one-dimensional structures at this small scale do not possess B.C.C. configuration as in bulk tungsten material. In order to analyze the relationship between multi-shell geometries and electronic transfer, the electronic and structural properties of tungsten wires and tubes including partial density of state and band structures which were determined and analyzed by quantum chemistry calculations. In addition, in order to understand the application feasibility of these nanowires and tubes on nano-devices such as field emitters or chemical catalysts, the electronic stability of these ultrathin tungsten nanowires was also investigated by density functional theory calculations.

  12. Perancangan Model Basis Data Sistem Operasional Berbasiskan Customer Relationship Management

    Directory of Open Access Journals (Sweden)

    Tanty Oktavia

    2013-12-01

    Full Text Available Data is a very important asset for a company since it describes the company’s running processes. Database as a part of the information system components provides a big influence in helping data integration in a company. Therefore, we need a system which can facilitate the availability of data to be processed and used as needed, This study takes a company engaged in the sale of bike and spare parts, namely PT TDI, as the object of the study. At this time, PT TDI uses an integrated system in helping the company's operations. Along with thevision and mission, PT TDI intends to build a new operating system by applying the concept of Customer Relationship Management (CRM which is believed to assist the company in maintaining relationships with customers using web-based platform. It aims to facilitate interaction with customers so that it can be done anytime and anywhere. This study implements the database design life cycle adjusted to the component aspects of CRM. The result achieved is a model that combines database CRM systems that can help companies improve relationships with customers.

  13. Dynamic causal modelling of brain-behaviour relationships.

    Science.gov (United States)

    Rigoux, L; Daunizeau, J

    2015-08-15

    In this work, we expose a mathematical treatment of brain-behaviour relationships, which we coin behavioural Dynamic Causal Modelling or bDCM. This approach aims at decomposing the brain's transformation of stimuli into behavioural outcomes, in terms of the relative contribution of brain regions and their connections. In brief, bDCM places the brain at the interplay between stimulus and behaviour: behavioural outcomes arise from coordinated activity in (hidden) neural networks, whose dynamics are driven by experimental inputs. Estimating neural parameters that control network connectivity and plasticity effectively performs a neurobiologically-constrained approximation to the brain's input-outcome transform. In other words, neuroimaging data essentially serves to enforce the realism of bDCM's decomposition of input-output relationships. In addition, post-hoc artificial lesions analyses allow us to predict induced behavioural deficits and quantify the importance of network features for funnelling input-output relationships. This is important, because this enables one to bridge the gap with neuropsychological studies of brain-damaged patients. We demonstrate the face validity of the approach using Monte-Carlo simulations, and its predictive validity using empirical fMRI/behavioural data from an inhibitory control task. Lastly, we discuss promising applications of this work, including the assessment of functional degeneracy (in the healthy brain) and the prediction of functional recovery after lesions (in neurological patients). Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Learning transcriptional regulatory relationships using sparse graphical models.

    Directory of Open Access Journals (Sweden)

    Xiang Zhang

    Full Text Available Understanding the organization and function of transcriptional regulatory networks by analyzing high-throughput gene expression profiles is a key problem in computational biology. The challenges in this work are 1 the lack of complete knowledge of the regulatory relationship between the regulators and the associated genes, 2 the potential for spurious associations due to confounding factors, and 3 the number of parameters to learn is usually larger than the number of available microarray experiments. We present a sparse (L1 regularized graphical model to address these challenges. Our model incorporates known transcription factors and introduces hidden variables to represent possible unknown transcription and confounding factors. The expression level of a gene is modeled as a linear combination of the expression levels of known transcription factors and hidden factors. Using gene expression data covering 39,296 oligonucleotide probes from 1109 human liver samples, we demonstrate that our model better predicts out-of-sample data than a model with no hidden variables. We also show that some of the gene sets associated with hidden variables are strongly correlated with Gene Ontology categories. The software including source code is available at http://grnl1.codeplex.com.

  15. How an Evolution View of Workplace Mentoring Relationships Helps Avoid Negative Experiences: The Developmental Relationship Mentoring Model in Action

    Science.gov (United States)

    Washington, Rhianon; Cox, Elaine

    2016-01-01

    In this paper, we explore how the use of a specific mentoring model focusing on the evolution of the relationship between mentor and mentee, may influence the incidence of failure. In our research we employed a case study methodology to examine a regional public service mentoring scheme in the UK where a developmental relationship mentoring model…

  16. Relationship Characteristics Associated with the Experience of Hurt in Romantic Relationships: A Test of the Relational Turbulence Model

    Science.gov (United States)

    Theiss, Jennifer A.; Knobloch, Leanne K.; Checton, Maria G.; Magsamen-Conrad, Kate

    2009-01-01

    We employed the relational turbulence model to identify (a) relationship characteristics associated with people's appraisals of hurtful messages, and (b) features of hurtful episodes and relationship characteristics that correspond with the directness of communication about hurt. We conducted a study in which 135 dating couples reported on their…

  17. Structural properties of silver doped hydroxyapatite and their biocompatibility

    International Nuclear Information System (INIS)

    Ciobanu, C.S.; Iconaru, S.L.; Pasuk, I.; Vasile, B.S.; Lupu, A.R.; Hermenean, A.; Dinischiotu, A.; Predoi, D.

    2013-01-01

    The aim of this study was to obtain a novel hydroxyapatite-based material with high biocompatibility. The structural properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The X-ray diffraction studies revealed the characteristic peaks of hydroxyapatite in each sample. Other phases or impurities were not observed. The scanning electron microscopy observations suggest that the doping components have no influence on the surface morphology of the samples, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O) and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) and X-ray Photoelectron Spectroscopy analyses. Nanocrystalline silver doped HAp stimulated viability and potentiated the activation of murine macrophages. - Highlights: ► A simple and low cost methodology to obtain Ag:HAp powders was described in this paper. ► Nanocrystalline Ag:HAp with different x Ag from can be obtained at 100 °C by co-precipitation. ► The study aims to understand the effects of Ag:HAp NPs with different x Ag on macrophage cells

  18. Structure-property maps and optimal inversion in configurational thermodynamics

    Science.gov (United States)

    Arnold, Björn; Díaz Ortiz, Alejandro; Hart, Gus L. W.; Dosch, Helmut

    2010-03-01

    Cluster expansions of first-principles density-functional databases in multicomponent systems are now used as a routine tool for the prediction of zero- and finite-temperature physical properties. The ability of producing large databases of various degrees of accuracy, i.e., high-throughput calculations, makes pertinent the analysis of error propagation during the inversion process. This is a very demanding task as both data and numerical noise have to be treated on equal footing. We have addressed this problem by using an analysis that combines the variational and evolutionary approaches to cluster expansions. Simulated databases were constructed ex professo to sample the configurational space in two different and complementary ways. These databases were in turn treated with different levels of both systematic and random numerical noise. The effects of the cross-validation level, size of the database, type of numerical imprecisions on the forecasting power of the expansions were extensively analyzed. We found that the size of the database is the most important parameter. Upon this analysis, we have determined criteria for selecting the optimal expansions, i.e., transferable expansions with constant forecasting power in the configurational space (a structure-property map). As a by-product, our study provides a detailed comparison between the variational cluster expansion and the genetic-algorithm approaches.

  19. A Multi-Stage Maturity Model for Long-Term IT Outsourcing Relationship Success

    Science.gov (United States)

    Luong, Ming; Stevens, Jeff

    2015-01-01

    The Multi-Stage Maturity Model for Long-Term IT Outsourcing Relationship Success, a theoretical stages-of-growth model, explains long-term success in IT outsourcing relationships. Research showed the IT outsourcing relationship life cycle consists of four distinct, sequential stages: contract, transition, support, and partnership. The model was…

  20. Data Relationships: Towards a Conceptual Model of Scientific Data Catalogs

    Science.gov (United States)

    Hourcle, J. A.

    2008-12-01

    As the amount of data, types of processing and storage formats increase, the total number of record permutations increase dramatically. The result is an overwhelming number of records that make identifying the best data object to answer a user's needs more difficult. The issue is further complicated as each archive's data catalog may be designed around different concepts - - anything from individual files to be served, series of similarly generated and processed data, or something entirely different. Catalogs may not only be flat tables, but may be structured as multiple tables with each table being a different data series, or a normalized structure of the individual data files. Merging federated search results from archives with different catalog designs can create situations where the data object of interest is difficult to find due to an overwhelming number of seemingly similar or entirely unwanted records. We present a reference model for discussing data catalogs and the complex relationships between similar data objects. We show how the model can be used to improve scientist's ability to quickly identify the best data object for their purposes and discuss technical issues required to use this model in a federated system.

  1. Exploring Solid-State Structure and Physical Properties: A Molecular and Crystal Model Exercise

    Science.gov (United States)

    Bindel, Thomas H.

    2008-01-01

    A crystal model laboratory exercise is presented that allows students to examine relations among the microscopic-macroscopic-symbolic levels, using crystalline mineral samples and corresponding crystal models. Students explore the relationship between solid-state structure and crystal form. Other structure-property relationships are explored. The…

  2. Sexual Dimorphism and Population Differences in Structural Properties of Barn Swallow (Hirundo rustica Wing and Tail Feathers.

    Directory of Open Access Journals (Sweden)

    Péter L Pap

    Full Text Available Sexual selection and aerodynamic forces affecting structural properties of the flight feathers of birds are poorly understood. Here, we compared the structural features of the innermost primary wing feather (P1 and the sexually dimorphic outermost (Ta6 and monomorphic second outermost (Ta5 tail feathers of barn swallows (Hirundo rustica from a Romanian population to investigate how sexual selection and resistance to aerodynamic forces affect structural differences among these feathers. Furthermore, we compared structural properties of Ta6 of barn swallows from six European populations. Finally, we determined the relationship between feather growth bars width (GBW and the structural properties of tail feathers. The structure of P1 indicates strong resistance against aerodynamic forces, while the narrow rachis, low vane density and low bending stiffness of tail feathers suggest reduced resistance against airflow. The highly elongated Ta6 is characterized by structural modifications such as large rachis width and increased barbule density in relation to the less elongated Ta5, which can be explained by increased length and/or high aerodynamic forces acting at the leading tail edge. However, these changes in Ta6 structure do not allow for full compensation of elongation, as reflected by the reduced bending stiffness of Ta6. Ta6 elongation in males resulted in feathers with reduced resistance, as shown by the low barb density and reduced bending stiffness compared to females. The inconsistency in sexual dimorphism and in change in quality traits of Ta6 among six European populations shows that multiple factors may contribute to shaping population differences. In general, the difference in quality traits between tail feathers cannot be explained by the GBW of feathers. Our results show that the material and structural properties of wing and tail feathers of barn swallows change as a result of aerodynamic forces and sexual selection, although the

  3. Biochemical and Structural Properties of Mouse Kynurenine Aminotransferase III

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Robinson, H; Cai, T; Tagle, D; Li, J

    2009-01-01

    Kynurenine aminotransferase III (KAT III) has been considered to be involved in the production of mammalian brain kynurenic acid (KYNA), which plays an important role in protecting neurons from overstimulation by excitatory neurotransmitters. The enzyme was identified based on its high sequence identity with mammalian KAT I, but its activity toward kynurenine and its structural characteristics have not been established. In this study, the biochemical and structural properties of mouse KAT III (mKAT III) were determined. Specifically, mKAT III cDNA was amplified from a mouse brain cDNA library, and its recombinant protein was expressed in an insect cell protein expression system. We established that mKAT III is able to efficiently catalyze the transamination of kynurenine to KYNA and has optimum activity at relatively basic conditions of around pH 9.0 and at relatively high temperatures of 50 to 60C. In addition, mKAT III is active toward a number of other amino acids. Its activity toward kynurenine is significantly decreased in the presence of methionine, histidine, glutamine, leucine, cysteine, and 3-hydroxykynurenine. Through macromolecular crystallography, we determined the mKAT III crystal structure and its structures in complex with kynurenine and glutamine. Structural analysis revealed the overall architecture of mKAT III and its cofactor binding site and active center residues. This is the first report concerning the biochemical characteristics and crystal structures of KAT III enzymes and provides a basis toward understanding the overall physiological role of mammalian KAT III in vivo and insight into regulating the levels of endogenous KYNA through modulation of the enzyme in the mouse brain.

  4. Structure-property relations in engineered semiconductor nanomaterials (Conference Presentation)

    Science.gov (United States)

    Hollingsworth, Jennifer A.; Htoon, Han

    2016-09-01

    Particle-size or `quantum-confinement' effects have been used for decades to tune semiconductor opto-electronic properties. More recently, particle size control as the primary means for properties control has been succeeded by nanoscale hetero-structuring. In this case, the nanosized particle is modified to include internal, nanoscale interfaces, generally defined by compositional variations that induce additional changes to semiconductor properties. These changes can entail enhancements to the size-induced properties as well as unexpected or `emergent' behaviors. Common structural motifs include enveloping a spherical semiconductor nanocrystal, i.e., a quantum dot, within a shell of a different composition. In this talk, I will discuss how solution-phase synthesis can be used to create these structures with precisely `engineered' complexity. Most notably, I will review our experiences with so-called `giant' quantum dots that, due to their internal nanoscale structure, exhibit a range of novel behaviors, including being non-blinking and non-photobleaching (Chen et al. J. Am. Chem. Soc. 2008, 130, 5026; Ghosh et al. J. Am. Chem. Soc. 2012, 134, 9634; Dennis et al. Nano Lett. 2012 12, 5545; Acharya et al. J. Am. Chem. Soc. 2015, 137, 3755), and remarkably efficient emitters of `multi-excitons' due to extreme suppression of Auger recombination (Mangum et al. Nanoscale 2014, 6, 3712; Gao et al. Adv. Optical Mater. 2015, 3, 39). I will discuss recent work extending non-blinking behavior to the blue/green and "dual-color" emission, and show how correlated optical/structural characterization can reveal new information regarding structure-property relations to guide new nanomaterials development (Orfield et al. ACS Nano, Article ASAP).

  5. Thermochemical and structural properties of DMAN-“proton sponges”

    International Nuclear Information System (INIS)

    Dávalos, Juan Z.; Lago, Alexsandre F.; Costa, José C.S.; Santos, Luís M.N.B.F.; González, Javier

    2012-01-01

    Highlights: ► We determined the enthalpy of formation Δ f H m o (g) of neutral and protonated DMAN. ► It has been estimated the “strain” effect and hydrogen bond enthalpies in DMAN-H + . ► GB gas phase basicities of naphthalene proton sponges are compared with their pK a . - Abstract: We report a study on the energetics and structural properties of naphthalene-based proton sponges and their corresponding protonated cations. In particular, we have determined the experimental standard enthalpies of formation in the gas phase at T = 298.15 K, Δ f H m o (g), for the neutral and protonated DMAN [1,8-bis (dimethylamino)-naphthalene], (221.0 ± 7.3) and (729.0 ± 11.1) kJ·mol −1 , respectively. A reliable experimental estimation of enthalpy associated with “strain” effect and hydrogen bond intramolecular (included within “enhanced basicity”, EB) contributions to the basicity of DMAN, were deduced from isodesmic reactions, −(29.1 ± 4.6) and (87.1 ± 11.9) kJ·mol −1 , respectively. The gas-phase basicities (GB) of naphthalene-based proton sponges are compared with the corresponding aqueous basicities (pK a ), covering a range of 149 kJ·mol −1 in GB and 11.5 in pK a . Density functional calculations at the M05-2X/6-311++G(d,p) level of theory were used to check the consistency of the experimental results and also to estimate the unavailable GB values of the considered species.

  6. Tyrosine aminotransferase: biochemical and structural properties and molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Mehere, P.; Robinson, H.; Han, Q.; Lemkul, J. A.; Vavricka, C. J.; Bevan, D. R.; Li, J.

    2010-11-01

    Tyrosine aminotransferase (TAT) catalyzes the transamination of tyrosine and other aromatic amino acids. The enzyme is thought to play a role in tyrosinemia type II, hepatitis and hepatic carcinoma recovery. The objective of this study is to investigate its biochemical and structural characteristics and substrate specificity in order to provide insight regarding its involvement in these diseases. Mouse TAT (mTAT) was cloned from a mouse cDNA library, and its recombinant protein was produced using Escherichia coli cells and purified using various chromatographic techniques. The recombinant mTAT is able to catalyze the transamination of tyrosine using {alpha}-ketoglutaric acid as an amino group acceptor at neutral pH. The enzyme also can use glutamate and phenylalanine as amino group donors and p-hydroxy-phenylpyruvate, phenylpyruvate and alpha-ketocaproic acid as amino group acceptors. Through macromolecular crystallography we have determined the mTAT crystal structure at 2.9 {angstrom} resolution. The crystal structure revealed the interaction between the pyridoxal-5'-phosphate cofactor and the enzyme, as well as the formation of a disulphide bond. The detection of disulphide bond provides some rational explanation regarding previously observed TAT inactivation under oxidative conditions and reactivation of the inactive TAT in the presence of a reducing agent. Molecular dynamics simulations using the crystal structures of Trypanosoma cruzi TAT and human TAT provided further insight regarding the substrate-enzyme interactions and substrate specificity. The biochemical and structural properties of TAT and the binding of its cofactor and the substrate may help in elucidation of the mechanism of TAT inhibition and activation.

  7. Tyrosine Aminotransferase: Biochemical and Structural Properties and Molecular Dynamics Simulations

    Energy Technology Data Exchange (ETDEWEB)

    P Mehere; Q Han; J Lemkul; C Vavricka; H Robinson; D Bevan; J Li

    2011-12-31

    Tyrosine aminotransferase (TAT) catalyzes the transamination of tyrosine and other aromatic amino acids. The enzyme is thought to play a role in tyrosinemia type II, hepatitis and hepatic carcinoma recovery. The objective of this study is to investigate its biochemical and structural characteristics and substrate specificity in order to provide insight regarding its involvement in these diseases. Mouse TAT (mTAT) was cloned from a mouse cDNA library, and its recombinant protein was produced using Escherichia coli cells and purified using various chromatographic techniques. The recombinant mTAT is able to catalyze the transamination of tyrosine using {alpha}-ketoglutaric acid as an amino group acceptor at neutral pH. The enzyme also can use glutamate and phenylalanine as amino group donors and p-hydroxy-phenylpyruvate, phenylpyruvate and alpha-ketocaproic acid as amino group acceptors. Through macromolecular crystallography we have determined the mTAT crystal structure at 2.9 {angstrom} resolution. The crystal structure revealed the interaction between the pyridoxal-5'-phosphate cofactor and the enzyme, as well as the formation of a disulphide bond. The detection of disulphide bond provides some rational explanation regarding previously observed TAT inactivation under oxidative conditions and reactivation of the inactive TAT in the presence of a reducing agent. Molecular dynamics simulations using the crystal structures of Trypanosoma cruzi TAT and human TAT provided further insight regarding the substrate-enzyme interactions and substrate specificity. The biochemical and structural properties of TAT and the binding of its cofactor and the substrate may help in elucidation of the mechanism of TAT inhibition and activation.

  8. Doctor-patient relationships in general practice--a different model.

    Science.gov (United States)

    Kushner, T

    1981-09-01

    Philosophical concerns cannot be excluded from even a cursory examination of the physician-patient relationship. Two possible alternatives for determining what this relationship entails are the teleological (outcome) approach vs the deontological (process) one. Traditionally, this relationship has been structured around the 'clinical model' which views the physician-patient relationship in teleological terms. Data on the actual content of general medical practice indicate the advisability of reassessing this relationship, and suggest that the 'clinical model' may be too limiting, and that a more appropriate basis for the physician-patient relationship is one described in this paper as the 'relational model'.

  9. Linear Equating for the NEAT Design: Parameter Substitution Models and Chained Linear Relationship Models

    Science.gov (United States)

    Kane, Michael T.; Mroch, Andrew A.; Suh, Youngsuk; Ripkey, Douglas R.

    2009-01-01

    This paper analyzes five linear equating models for the "nonequivalent groups with anchor test" (NEAT) design with internal anchors (i.e., the anchor test is part of the full test). The analysis employs a two-dimensional framework. The first dimension contrasts two general approaches to developing the equating relationship. Under a "parameter…

  10. Optical and structural properties of porous zinc oxide fabricated via electrochemical etching method

    International Nuclear Information System (INIS)

    Ching, C.G.; Lee, S.C.; Ooi, P.K.; Ng, S.S.; Hassan, Z.; Hassan, H. Abu; Abdullah, M.J.

    2013-01-01

    Highlights: • Hillock like porous structure zinc oxide was obtained via electrochemical etching. • Anisotropic dominance etching process by KOH etchant. • Reststrahlen features are sensitive to multilayer porous structure. • Determination of porosity from IR reflectance spectrum. -- Abstract: We investigated the optical and structural properties of porous zinc oxide (ZnO) thin film fabricated by ultraviolet light-assisted electrochemical etching. This fabrication process used 10 wt% potassium hydroxide solution as an electrolyte. Hillock-like porous ZnO films were successfully fabricated according to the field emission scanning electron microscopy results. The cross-sectional study of the sample indicated that anisotropic-dominated etching process occurred. However, the atomic force microscopic results showed an increase in surface roughness of the sample after electrochemical etching. A resonance hump induced by the porous structure was observed in the infrared reflectance spectrum. Using theoretical modeling technique, ZnO porosification was verified, and the porosity of the sample was determined

  11. Neutron beam applications; technical development for thermodynamic and structural properties of micelles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soon Chul; Suh, Song Hyuck; Min, Yoong Ki; Ahn, Eun Ju [Andong National University, Andong (Korea)

    2002-03-01

    Two non-ionic surfactants, which are the non-ionic surfactants with the polydisperse properties and non-ionic surfactant with the ellipsoidal structure, and which were measured by the small-angle neutron scattering installed in the Korea Atomic Energy Research Institute have been analyzed by using the IGOR Program code. Through the analysis of the SANS data, the strengths and weaknesses of the IGOR program code have been tested in details. To reinforce the IGOR program, the computer programs which are based on the Percus-Yevick, hypernetted-chain, Rogers-Young, and density functional approximation have been developed for the model micelles, and their results have been compared with the computer simulations. It is expected that this study would be applied to study the thermodynamic and structural properties of polymers with the complex structure. 22 refs., 20 figs., 7 tabs. (Author)

  12. A Systematic Review of the Effect of Therapists' Internalized Models of Relationships on the Quality of the Therapeutic Relationship.

    Science.gov (United States)

    Steel, Catherine; Macdonald, James; Schroder, Thomas

    2018-01-01

    Previous reviews have found equivocal evidence of an association between therapists' internalized relational models and the therapeutic relationship and have neglected empirical literature based on Sullivan's notion of introject. This review expanded upon previous reviews to examine the effect of therapist internalized relational models on a broader conceptualization of the therapeutic relationship. Systematic search processes identified 22 papers measuring therapist attachment and/or introject and therapeutic relationship: 19 on therapist attachment, 5 on introject with 2 overlapping. Overall, despite heterogeneity in design and variable methodological quality, evidence suggests that therapist attachment affects therapeutic relationship quality, observed in client-rated evaluation, therapist negative countertransference, empathy, and problems in therapy. Interaction effects between client and therapist attachment style were also found. Evidence suggesting that therapist introject also affects therapeutic relationship quality, including therapists' manner and feelings toward their clients, was stronger. Evidence clearly shows that therapists' internalized relational models affect the therapeutic relationship. More research is necessary to clarify exactly how therapist and client internalized relational models interact and translate these findings into clinical practice. © 2017 Wiley Periodicals, Inc.

  13. Parameterizing amylose chain-length distributions for biosynthesis-structure-property relations.

    Science.gov (United States)

    Nada, Sharif S; Zou, Wei; Li, Changfeng; Gilbert, Robert G

    2017-11-01

    Amylose, one of the components of starch, is a glucose polymer consisting largely of long, linear chains with a few long-chain branch points. The chain-length (molecular weight) distribution (CLD) of the component chains of amylose can provide information on amylose biosynthesis-structure-property relations, as has been done previously by fitting amylopectin CLDs to a model with physically meaningful parameters. Due to the presence of long chains, the CLD of amylose can currently best be obtained by size-exclusion chromatography, a technique that suffers from band-broadening effects which alter the observed distribution. The features of the multiple regions present in amylose chain-length distributions are also difficult to resolve, an issue that combines with band broadening to compound the difficulty of analysis and subsequent parameterization of the structural characteristics of amylose. A new method is presented to fit these distributions with biologically meaningful parameters in a way that accounts for band broadening. This is achieved by assuming that band broadening takes the form of a simple Gaussian over a relatively small region and that chain stoppage is a random process independent of the length of the substrate chain over the same region; these assumptions are relatively weak and expected to be frequently applicable. The method provides inbuilt consistency tests for its applicability to a given data set and, in cases where it is applicable, allows for the first nonempirical parameterization of amylose biosynthesis-structure-property relations from CLDs by using parameters directly linked to the activities of the enzymes responsible for chain growth and chain stoppage. Graphical abstract Model calculation illustrating the method described and showing the division between the three characteristic regions of a typical amylose chain-length distribution.

  14. Design, synthesis, and characterization of new phosphazene related materials, and study the structure property correlations

    Science.gov (United States)

    Tian, Zhicheng

    The work described in this thesis is divided into three major parts, and all of which involve the exploration of the chemistry of polyphosphazenes. The first part (chapters 2 and 3) of my research is synthesis and study polyphoshazenes for biomedical applications, including polymer drug conjugates and injectable hydrogels for drug or biomolecule delivery. The second part (chapters 4 and 5) focuses on the synthesis of several organic/inorganic hybrid polymeric structures, such as diblock, star, brush and palm tree copolymers using living cationic polymerization and atom transfer radical polymerization techniques. The last part (chapters 6 and 7) is about exploratory synthesis of new polymeric structures with fluorinated side groups or cycloaliphatic side groups, and the study of new structure property relationships. Chapter 1 is an outline of the fundamental concepts for polymeric materials, as such the history, important definitions, and some introductory material for to polymer chemistry and physics. The chemistry and applications of phopshazenes is also briefly described. Chapter 2 is a description of the design, synthesis, and characterization of development of a new class of polymer drug conjugate materials based on biodegradable polyphosphazenes and antibiotics. Poly(dichlorophosphazene), synthesized by a thermal ring opening polymerization, was reacted with up to 25 mol% of ciprofloxacin or norfloxacin and three different amino acid esters (glycine, alanine, or phenylalanine) as cosubstituents via macromolecular substitutions. Nano/microfibers of several selected polymers were prepared by an electrospinning technique. Chapter 3 is concerned with the development of a class of injectable and biodegradable hydrogels based on water-soluble poly(organophosphazenes) containing oligo(ethylene glycol) methyl ethers and glycine ethyl esters. The hydrogels can be obtained by mixing alpha-cyclodextrin aqueous solution and poly(organophosphazenes) aqueous solution in

  15. Building Customer Relationships: A Model for Vocational Education and Training Delivery.

    Science.gov (United States)

    Jarratt, Denise G.; Murphy, Tom; Lowry, Diannah

    1997-01-01

    Review of the theory of relational marketing and interviews with training providers identified a training delivery model that includes elements of trust and commitment, investment by relationship partners, and knowledge exchange, supporting relationship longevity. (SK)

  16. Synthesised model of market orientation-business performance relationship

    Directory of Open Access Journals (Sweden)

    G. Nwokah

    2006-12-01

    Full Text Available Purpose: The purpose of this paper is to assess the impact of market orientation on the performance of the organisation. While much empirical works have centered on market orientation, the generalisability of its impact on performance of the Food and Beverages organisations in the Nigeria context has been under-researched. Design/Methodology/Approach: The study adopted a triangulation methodology (quantitative and qualitative approach. Data was collected from key informants using a research instrument. Returned instruments were analyzed using nonparametric correlation through the use of the Statistical Package for Social Sciences (SPSS version 10. Findings: The study validated the earlier instruments but did not find any strong association between market orientation and business performance in the Nigerian context using the food and beverages organisations for the study. The reasons underlying the weak relationship between market orientation and business performance of the Food and Beverages organisations is government policies, new product development, diversification, innovation and devaluation of the Nigerian currency. One important finding of this study is that market orientation leads to business performance through some moderating variables. Implications: The study recommends that Nigerian Government should ensure a stable economy and make economic policies that will enhance existing business development in the country. Also, organisations should have performance measurement systems to detect the impact of investment on market orientation with the aim of knowing how the organisation works. Originality/Value: This study significantly refines the body of knowledge concerning the impact of market orientation on the performance of the organisation, and thereby offers a model of market orientation and business performance in the Nigerian context for marketing scholars and practitioners. This model will, no doubt, contribute to the body of

  17. Accessing Data Bases Through Interface Views Using a Unified Graph-Oriented Entity-Relationship Model

    DEFF Research Database (Denmark)

    Kraft, Peter; Sørensen, Jens Otto

    with a unified graphic model is more efficient and less error-prone than working with more complex ER models and models based on lexical description. Key terms: Entity-relationship model, path expressions, entity-relationship language, derived interface view, view updates, graphical models.......Interface Abstract: The paper describes an Entity Relationship (ER) model with a diagrammed schema and extensions modeled into a graph. The semantics of schema symbols are fundamentally simple implying a unified model where given conceptualizations of environments are diagrammed uniquely...

  18. An Investment Model Analysis of Relationship Stability among Women Court-Mandated to Violence Interventions

    Science.gov (United States)

    Rhatigan, Deborah L.; Moore, Todd M.; Stuart, Gregory L.

    2005-01-01

    This investigation examined relationship stability among 60 women court-mandated to violence interventions by applying a general model (i.e., Rusbult's 1980 Investment Model) to predict intentions to leave current relationships. As in past research, results showed that Investment Model predictions were supported such that court-mandated women who…

  19. Polymers for enhanced oil recovery : A paradigm for structure-property relationship in aqueous solution

    NARCIS (Netherlands)

    Wever, D. A. Z.; Picchioni, F.; Broekhuis, A. A.

    2011-01-01

    Recent developments in the field of water-soluble polymers aimed at enhancing the aqueous solution viscosity are reviewed. Classic and novel associating water-soluble polymers for enhanced oil recovery (EOR) applications are discussed along with their limitations. Particular emphasis is placed on

  20. Structure-Property Relationships of Semiconducting Polymers for Flexible and Durable Polymer Field-Effect Transistors.

    Science.gov (United States)

    Kim, Min Je; Jung, A-Ra; Lee, Myeongjae; Kim, Dongjin; Ro, Suhee; Jin, Seon-Mi; Nguyen, Hieu Dinh; Yang, Jeehye; Lee, Kyung-Koo; Lee, Eunji; Kang, Moon Sung; Kim, Hyunjung; Choi, Jong-Ho; Kim, BongSoo; Cho, Jeong Ho

    2017-11-22

    We report high-performance top-gate bottom-contact flexible polymer field-effect transistors (FETs) fabricated by flow-coating diketopyrrolopyrrole (DPP)-based and naphthalene diimide (NDI)-based polymers (P(DPP2DT-T2), P(DPP2DT-TT), P(DPP2DT-DTT), P(NDI2OD-T2), P(NDI2OD-F2T2), and P(NDI2OD-Se2)) as semiconducting channel materials. All of the polymers displayed good FET characteristics with on/off current ratios exceeding 10 7 . The highest hole mobility of 1.51 cm 2 V -1 s -1 and the highest electron mobility of 0.85 cm 2 V -1 s -1 were obtained from the P(DPP2DT-T2) and P(NDI2OD-Se2) polymer FETs, respectively. The impacts of the polymer structures on the FET performance are well-explained by the interplay between the crystallinity, the tendency of the polymer backbone to adopt an edge-on orientation, and the interconnectivity of polymer fibrils in the film state. Additionally, we demonstrated that all of the flexible polymer-based FETs were highly resistant to tensile stress, with negligible changes in their carrier mobilities and on/off ratios after a bending test. Conclusively, these high-performance, flexible, and durable FETs demonstrate the potential of semiconducting conjugated polymers for use in flexible electronic applications.

  1. Electron irradiation effects on partially fluorinated polymer films: Structure-property relationships

    CERN Document Server

    Nasef, M M

    2003-01-01

    The effects of electron beam irradiation on two partially fluorinated polymer films i.e. poly(vinylidene fluoride) (PVDF) and poly(ethylene-tetrafluoroethylene) copolymer (ETFE) are studied at doses ranging from 100 to 1200 kGy in air at room temperature. Chemical structure, thermal and mechanical properties of irradiated films are investigated. FTIR show that both PVDF and ETFE films undergo similar changes in their chemical structures including the formation of carbonyl groups and double bonding. The changes in melting and crystallisation temperatures (T sub m and T sub c) in both irradiated films are functions of irradiation dose and reflect the disorder in the chemical structure caused by the competition between crosslinking and chain scission. The heat of melting (DELTA H sub m) and the degree of crystallinity (X sub c) of PVDF films show no significant changes with the dose increase, whereas those of ETFE films are reduced rapidly after the first 100 kGy. The tensile strength of PVDF films is improved b...

  2. Revisiting structure-property relationship of pH-responsive polymers for drug delivery applications.

    Science.gov (United States)

    Bazban-Shotorbani, Salime; Hasani-Sadrabadi, Mohammad Mahdi; Karkhaneh, Akbar; Serpooshan, Vahid; Jacob, Karl I; Moshaverinia, Alireza; Mahmoudi, Morteza

    2017-05-10

    pH-responsive polymers contain ionic functional groups as pendants in their structure. The total number of charged groups on polymer chains determines the overall response of the system to changes in the external pH. This article reviews various pH-responsive polymers classified as polyacids (e.g., carboxylic acid based polymers, sulfonamides, anionic polysaccharides, and anionic polypeptides) and polybases (e.g., polyamines, pyridine and imidazole containing polymers, cationic polysaccharides, and cationic polypeptides). We correlate the pH variations in the body at the organ level (e.g., gastrointestinal tract and vaginal environment), tissue level (e.g., cancerous and inflamed tissues), and cellular level (e.g., sub-cellular organelles), with the intrinsic properties of pH-responsive polymers. This knowledge could help to select more effective ('smart') polymeric systems based on the biological target. Considering the pH differences in the body, various drug delivery systems can be designed by utilizing smart biopolymeric compounds with the required pH-sensitivity. We also review the pharmaceutical application of pH-responsive polymeric carriers including hydrogels, polymer-drug conjugates, micelles, dendrimers, and polymersomes. © 2016.

  3. Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure-property relationships

    International Nuclear Information System (INIS)

    Naebe, Minoo; Lin Tong; Wang Xungai; Staiger, Mark P; Dai Liming

    2008-01-01

    Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde

  4. Synthesis and Structure-Property Relationships of Poly(sulfone)s for Anion Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, JL; Moore, HD; Hibbs, MR; Hickner, MA

    2013-10-05

    Membranes based on cationic polymers that conduct anions are important for enabling alkaline membrane fuel cells and other solid-state electrochemical devices that operate at high pH. Anion exchange membranes with poly(arylene ether sulfone) backbones are demonstrated by two routes: chloromethylation of commercially available poly(sulfone)s or radical bromination of benzylmethyl moieties in poly(sulfone)s containing tetramethylbisphenol A monomer residues. Polymers with tethered trimethylbenzyl ammonium moieties resulted from conversion of the halomethyl groups by quaternization with trimethyl amine. The water uptake of the chloromethylated polymers was dependent on the type of poly(sulfone) backbone for a given IEC. Bisphenol A-based Udel (R) poly(sulfone) membranes swelled in water to a large extent while membranes from biphenol-based Radel (R) poly(sulfone), a stiffer backbone than Udel, only showed moderate water uptake. The water uptake of cationic poly(sulfone)s was further reduced by synthesizing tetramethylbisphenol A and 4,4-biphenol-containing poly(sulfone) copolymers where the ionic groups were clustered on the tetramethylbisphenol A residues. The conductivity of all samples scaled with the bulk water uptake. The hydration number of the membranes could be increased by casting membranes from the ionic form polymers versus converting the halomethyl form cast polymers to ionic form in the solid state. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1790-1798, 2013

  5. Novel multiphase systems based on thermoplastic chitosan: Analysis of the structure-properties relationships

    Science.gov (United States)

    Avérous, Luc; Pollet, Eric

    2016-03-01

    In the last years, biopolymers have attracted great attention. It is for instance the case of chitosan, a linear polysaccharide. It is a deacetylated derivative of chitin, which is the second most abundant polysaccharide found in nature after cellulose. Chitosan has been found to be nontoxic, biodegradable, biofunctional, and biocompatible in addition to having antimicrobial and antifungal properties, and thus has a great potential for environmental (packaging,) or biomedical applications.For preparing chitosan-based materials, only solution casting or similar methods have been used in all the past studies. Solution casting have the disadvantage in low efficiency and difficulty in scaling-up towards industrial applications. Besides, a great amount of environmentally unfriendly chemical solvents are used and released to the environment in this method. The reason for not using a melt processing method like extrusion or kneading in the past studies is that chitosan, like many other polysaccharides such as starch, has very low thermal stability and degrade prior to melting. Therefore, even if the melt processing method is more convenient and highly preferred for industrial production, its adaptation for polysaccharide-based materials remains very difficult. However, our recently published studies has demonstrated the successful use of an innovative melt processing method (internal mixer, extrusion,) as an alternative route to solution casting, for preparing materials based on thermoplastic chitosan. These promising thermoplastic materials, obtained by melt processing, have been the main topic of recent international projects, with partners from different countries Multiphase systems based on various renewable plasticizers have been elaborated and studied. Besides, different blends, and nano-biocomposites based on nanoclays, have been elaborated and fully analyzed. The initial consortium of this vast project was based on an international consortium (Canada, Australia, France). This project is currently ongoing and open, with new international academic partners (Mexico, Brazil and Spain).

  6. Structure-Property Relationships and the Mixed Network Former Effect in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, Marcel; Mauro, John C.

    compositions by substituting Al2O3 for SiO2. We also investigate the various roles of sodium in the glasses including charge compensation of tetrahedral aluminum and boron atoms and formation of non-bridging oxygen. We find that mechanical properties (density, elastic moduli, and hardness), glass transition...... temperature, and kinetic and thermodynamic liquid fragilities all exhibit nonlinear variations with changes in the relative network former concentrations. The structural origin of these nonlinear variations is elucidated through nuclear magnetic resonance measurements and analysis. Finally, we explore...

  7. Composition-structure-properties relationship of strontium borate glasses for medical applications.

    Science.gov (United States)

    Hasan, Muhammad S; Werner-Zwanziger, Ulrike; Boyd, Daniel

    2015-07-01

    We have synthesized TiO2 doped strontium borate glasses, 70B2O3-(30-x)SrO-xTiO2 and 70B2 O3 -20SrO(10-x)Na2 O-xTiO2 . The composition dependence of glass structure, density, thermal properties, durability, and cytotoxicity of degradation products was studied. Digesting the glass in mineral acid and detecting the concentrations of various ions using an ICP provided the actual compositions that were 5-8% deviated from the theoretical values. The structure was investigated by means of (11)B magic angle spinning (MAS) NMR spectroscopy. DSC analyses provided the thermal properties and the degradation rates were measured by measuring the weight loss of glass disc-samples in phosphate buffered saline at 37°C in vitro. Finally, the MTT assay was used to analyze the cytotoxicity of the degradation products. The structural analysis revealed that replacing TiO2 for SrO or Na2 O increased the BO3/BO4 ratio suggesting the network-forming role of TiO2 . Thermal properties, density, and degradation rates also followed the structural changes. Varying SrO content predominantly controlled the degradation rates, which in turn controlled the ion release kinetics. A reasonable control (2-25% mass loss in 21 days) over mass loss was achieved in current study. Even though, very high concentrations (up to 5500 ppm B, and 1200 ppm Sr) of ions were released from the ternary glass compositions that saturated the degradation media in 7 days, the degradation products from ternary glass system was found noncytotoxic. However, quaternary glasses demonstrated negative affect on cell viability due to very high (7000 ppm) Na ion concentration. All the glasses investigated in current study are deemed fast degrading with further control over degradation rates, release kinetics desirable. © 2014 Wiley Periodicals, Inc.

  8. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    Science.gov (United States)

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Structure/Property Relationships of Cyanate Ester Resins from Renewable Sources

    Science.gov (United States)

    2013-04-11

    with Near Zero Coefficient of Hygroscopic Expansion Δ Distribution A. Approved for public release; distribution is unlimited. Cyanate...distribution is unlimited. DSC of Creosol-Based Cyanate Esters 11 liquid at RT 120 kJ/mol Post-cure Tg: 153 °C (indicates degradation) m.p

  10. Structure-property relationships in NO x sensor materials composed of arrays of vanadium oxide nanoclusters

    Energy Technology Data Exchange (ETDEWEB)

    Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.; Ganegoda, Hasitha; Khan, M. Ishaque

    2017-12-01

    The mixed‐valent vanadium oxide based three‐dimensional framework structure species [Cd3(H2O)12V16IVV2VO36(OH)6(AO4)]∙24H2O, (A=V,S) (Cd3(VO)o) represents a rare example of an interesting sensor material which exhibits NOx {NO+NO2} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd3(VO)o decreases in air. Combined characterization studies revealed that the building block, {V18O42(AO4)} cluster, of 3‐D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadium which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd3(VO)o. Based on these results we propose that the changes in semiconducting properties of Cd3(VO)o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.

  11. Structure - property relationships in early transition metal based olefin polumerisation catalysts

    NARCIS (Netherlands)

    Beetstra, Dirk Johannes

    2005-01-01

    Polyolefines zoals polyetheen en polypropeen zijn belangrijke plastics die veel worden gebruikt in verpakkings- en constructiematerialen. Ze worden gemaakt met behulp van een katalysator. In zijn onderzoek bracht Dirk Beetstra kleine, maar fundamentele veranderingen aan in de chemische structuur van

  12. The structure-property relationships of powder processed Fe-Al-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Prichard, Paul D. [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D84 < 32 μm). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 μm. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 μm to 104 μm. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase α + DO3 structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  13. Structure-property relationships in NOx sensor materials composed of arrays of vanadium oxide nanoclusters

    Science.gov (United States)

    Putrevu, Naga Ravikanth; Darling, Seth B.; Segre, Carlo U.; Ganegoda, Hasitha; Khan, M. Ishaque

    2017-12-01

    The mixed-valent vanadium oxide based three-dimensional framework structure species [Cd3(H2O)12V16IVV2VO36(OH)6 (AO4)]·24H2O, (A = V,S) (Cd3(VO)o) represents a rare example of an interesting sensor material which exhibits NOx {NO + NO2} semiconducting gas sensor properties under ambient conditions. The electrical resistance of the sensor material Cd3(VO)o decreases in air. Combined characterization studies revealed that the building block, {V18O42(AO4)} cluster, of 3-D framework undergoes oxidation and remains intact for at least 2 months. The decrease in resistance is attributable to the reactivity of molecular oxygen towards vanadium which results in an increase in the oxidation state as well as the coordination number of vanadium center and decrease in band gap of Cd3(VO)o. Based on these results we propose that the changes in semiconducting properties of Cd3(VO)o under ambient conditions are due to the greater overlap between the O 2p and V 3d orbitals occurring during the oxidation.

  14. Easily oxidizable triarylamine materials with naphthalene and binaphthalene core: structure-properties relationship

    Czech Academy of Sciences Publication Activity Database

    Kerner, L.; Gmucová, K.; Kožíšek, J.; Petříček, Václav; Putala, M.

    2016-01-01

    Roč. 72, č. 44 (2016), s. 7081-7092 ISSN 0040-4020 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : triphenylamine * carbazole * regioselective amination * Sonogashira coupling * Negishi alkynylation * hole-transporting materials * OLED * cyclic voltammetry Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.651, year: 2016

  15. Studies of Structural Properties and Their Relationship to Critical Parameters in Superconducting Materials.

    Science.gov (United States)

    1984-02-28

    vibrational spectrum. The ternary phase diagrams, BaPbO 3-BaBiO 3- BaSnO3 (Fig. 3) and BaPbO -BaBiO -BaSbO (Fig. 4), have been determined to establish...Sb nuclei yield definitive proof that i8 - - - - - - Cr)Q Cr)Y 0 0m 0" -4 0 0 LoE BaSnO3 3 / X\\\\ \\N./ / /\\O 0 0 __- BaPbO 3 / BaBiO3 10 T 0 0 Fig. 3

  16. On the processing-structure-property relationship of ITO layers deposited on crystalline and amorphous Si

    International Nuclear Information System (INIS)

    Diplas, S.; Ulyashin, A.; Maknys, K.; Gunnaes, A.E.; Jorgensen, S.; Wright, D.; Watts, J.F.; Olsen, A.; Finstad, T.G.

    2007-01-01

    Indium-tin-oxide (ITO) antireflection coatings were deposited on crystalline Si (c-Si), amorphous hydrogenated Si (a-Si:H) and glass substrates at room temperature (RT), 160 deg. C and 230 deg. C by magnetron sputtering. The films were characterised using atomic force microscopy, transmission electron microscopy, angle resolved X-ray photoelectron spectroscopy, combined with resistance and transmittance measurements. The conductivity and refractive index as well as the morphology of the ITO films showed a significant dependence on the processing conditions. The films deposited on the two different Si substrates at higher temperatures have rougher surfaces compared to the RT ones due to the development of crystallinity and growth of columnar grains

  17. Structure-Property Relationships in Tough, Superabsorbent Thermoplastic Elastomers for Hemorrhage Control

    Science.gov (United States)

    Beyer, Frederick; Bain, Erich; Long, Tyler; Mrozek, Randy; Savage, Alice; Martin, Halie; Dadmun, Mark; Lenhart, Joseph

    Between 2001 and 2009, uncontrolled hemorrhaging from major trauma accounted for the deaths of roughly 80% of wounded soldiers with potentially survivable injuries. Modern hemostatic materials are limited in their ability to deliver therapeutic agents, causing tissue damage themselves, or being difficult to remove intact. The goal of this study is to create a mechanically robust polymer that takes up as much as 1000 wt% water in seconds while maintaining sufficient toughness to be removed intact from the wound intact. A thermoplastic elastomer scaffold in which physical crosslinks provide mechanical toughness might provide an appropriate combination of fast swelling and excellent toughness if the matrix material can be engineered to be strongly hydrophilic and swell rapidly. In this work, a commercial SBS triblock copolymer has been modified with poly(acrylic acid) side chains, resulting in materials that are superabsorbent but retain good mechanical properties when saturated. Although SAXS experiments failed to show any significant changes in morphology, even with 800 wt% water uptake, preliminary SANS experiments using selectively deuterated materials and swelling with D2O show significant changes in morphology. Our most recent findings will be presented.

  18. On structure-property relationship in nanostructured bainitic steel subjected to the quenching and partitioning process

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Ping [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Gao, Guhui, E-mail: gaogh@bjtu.edu.cn [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Han [Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf (Germany); Tan, Zhunli [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Misra, R.DK. [Laboratory for Excellence in Advanced Steel Research, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, TX 79968-0520 (United States); Bai, Bingzhe [Material Science & Engineering Research Center, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Tsinghua University, Key Laboratory of Advanced Material, School of Material Science and Engineering, Beijing 100084 (China)

    2016-04-20

    We elucidate here the mechanistic contribution of the application of quenching and partitioning (Q&P) concept to a high carbon Mn-Si-Cr steel in obtaining a multiphase microstructure comprising of martensite/austenite and nanostructured bainite (bainitic ferrite and nanometer-sized film-like retained austenite) that exhibited tensile strength of 1923 MPa and total elongation of 18.3%. The excellent mechanical properties are attributed to the enhanced refinement of blocky austenite islands obtained by the Q&P process. The austenite was stabilized by both carbon partitioning from martensite and bainite transformation. Compared with conventional heat treatment to produce nanostructured bainite, the total time is significantly reduced without degradation of mechanical properties.

  19. Study of Chemistry and Structure-Property Relationship on Tunable Plasmonic Nanostructures

    Science.gov (United States)

    Jing, Hao

    In this dissertation, the rational design and controllable fabrication of an array of novel plasmonic nanostructures with geometrically tunable optical properties are demonstrated, including metal-semiconductor hybrid hetero-nanoparticles, bimetallic noble metal nanoparticles and hollow nanostructures (nanobox and nanocage). Firstly, I have developed a robust wet chemistry approach to the geometry control of Ag-Cu2O core-shell nanoparticles through epitaxial growth of Cu2O nanoshells on the surfaces of various Ag nanostructures, such as quasi-spherical nanoparticles, nanocubes, and nanocuboids. Precise control over the core and the shell geometries enables me to develop detailed, quantitative understanding of how the Cu2O nanoshells introduce interesting modifications to the resonance frequencies and the extinction spectral line shapes of multiple plasmon modes of the Ag cores. Secondly, I present a detailed and systematic study of the controlled overgrowth of Pd on Au nanorods. The overgrowth of Pd nanoshells with fine-controlled dimensions and architectures on single-crystalline Au nanorods through seed-mediated growth protocol in the presence of various surfactants is investigated. Thirdly, I have demonstrated that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, I have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high index facets abundant on the particle surfaces. And the nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time-resolved plasmon-enhanced spectroscopic measurements, such as surface-enhanced Raman scattering (SERS). Last but not least, I have demonstrated that the capability of geometry control over Ag-Pd bimetallic hollow nanostructures through nanoscale galvanic replacement can be greatly enhanced by the use of appropriate mild reducing agents, such as ascorbic acid and formaldehyde. With the aid of mild reducing agents, we have been able to fine-tailor the compositions, interior architectures, and surface morphologies of Ag-Pd bimetallic hollow nanoparticles with increased structural complexity through surface ligand-free galvanic replacement processes at room temperature. This reducing agent-mediated galvanic replacement provides a unique way of achieving both enhanced optical tunability and optimized catalytic activities through deliberate control over the geometries of complex Ag-Pd bimetallic nanoparticles.

  20. Exploring the structure-properties relationships of novel polyamide thin film composite membranes

    DEFF Research Database (Denmark)

    Briceño, Kelly; Javakhishvili, Irakli; Guo, Haofei

    Polysulfone (PSU) is a material widely used in the fabrication of membranes for ultrafiltration and as a support for nanofiltration and reverse osmosis membranes. Interfacial polymerization usually combines amine and acid chloride monomers for the fabrication of thin film composite membranes[1...

  1. Symposium KK: Structure-Property Relationships in Biomineralized and Bio-mimetic Composites

    Science.gov (United States)

    2010-04-06

    Engineering, The Cooper Union for the Advancement of Science and Art , New York, New York. 11:30 AM KK1.9 Effect of Alport Syndrome Mutations in...Characterization. Miriam Estevez, Rogelio Rodriguez, Angel M Escamilla and Ana Leonor Rivera: Centra de Fisica Aplicada y Tecnologia Avanzada...Bioceramic for Bone Graft Jose I Arias’, Andrbnico Neira-Carrillo2, Mehrad Yazdani-Pedram2, Maria S Fernandez2 and Jose Luis Arias2: ’instituto Ciencias

  2. First-Principles Study of Structure Property Relationships of Monolayer (Hydroxy)Oxide-Metal Bifunctional Electrocatalysts

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph; Greeley, Jeffrey Philip

    2015-01-01

    under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth...... of information that is inaccessible by purely experimental means, and these structures, in turn, strongly suggest that a bifunctional reaction mechanism for alkaline HER will be operative at the interface between the films, the metal substrates, and the surrounding aqueous medium. This bifunctionality produces...... important changes in the calculated barriers of key elementary reaction steps, including water activation and dissociation, as compared to traditional monofunctional Pt surfaces. The successful identification of the structures of thin metal films and three-phase boundary catalysts is not only an important...

  3. New Synthetic Methods and Structure-Property Relationships in Neptunium, Plutonium, and Americium Borates. Final report

    International Nuclear Information System (INIS)

    Albrecht-Schmitt, Thomas Edward

    2013-01-01

    The past three years of support by the Heavy Elements Chemistry Program have been highly productive in terms of advanced degrees awarded, currently supported graduate students, peer-reviewed publications, and presentations made at universities, national laboratories, and at international conferences. Ph.D. degrees were granted to Shuao Wang and Juan Diwu, who both went on to post-doctoral appointments at the Glenn T. Seaborg Center at Lawrence Berkeley National Laboratory with Jeff Long and Ken Raymond, respectively. Pius Adelani completed his Ph.D. with me and is now a post-doc with Peter C. Burns. Andrea Alsobrook finished her Ph.D. and is now a post-doc at Savannah River with Dave Hobbs. Anna Nelson completed her Ph.D. and is now a post-doc with Rod Ewing at the University of Michigan. As can be gleaned from this list, students supported by the Heavy Elements Chemistry grant have remained interested in actinide science after leaving my program. This follows in line with previous graduates in this program such as Richard E. Sykora, who did his post-doctoral work at Oak Ridge National Laboratory with R. G. Haire, and Amanda C. Bean, who is a staff scientist at Los Alamos National Laboratory, and Philip M. Almond and Thomas C. Shehee, who are both staff scientists at Savannah River National Laboratory, Gengbang Jin who is a staff scientist at Argonne National Lab, and Travis Bray who has been a post-doc at both LBNL and ANL. Clearly this program is serving as a pipe-line for students to enter into careers in the national laboratories. About half of my students depart the DOE complex for academia or industry. My undergraduate researchers also remain active in actinide chemistry after leaving my group. Dan Wells was a productive undergraduate of mine, and went on to pursue a Ph.D. on uranium and neptunium chalcogenides with Jim Ibers at Northwestern. After earning his Ph.D., he went directly into the nuclear industry

  4. Structure-property relationships in directionally solidified single crystal NiAl

    Science.gov (United States)

    Noebe, R. D.; Kim, J. T.; Gibala, R.

    1987-01-01

    The ordered intermetallic alloy NiAl is being considered as a potential high temperature structural material, but lack of ductility at ambient temperatures, especially in polycrystalline form, is presently a major obstacle in achieving this goal. Even general agreement of the intrinsic ductility that can be achieved in monocrystals is in dispute. In order to understand this problem, two directionally solidified ingots of NiAl which displayed known differences in ductility were characterized in sufficient detail to identify the corresponding microstructural differences. It was found that the type and size of casting defects, i.e., porosity, present in the material were the major factors in controlling ductility of NiAl single crystals and could explain the order of magnitude variance in fracture strains reported in the literature.

  5. Structure/Property Relationships of Poly(L-lactic Acid/Mesoporous Silica Nanocomposites

    Directory of Open Access Journals (Sweden)

    Javier Gudiño-Rivera

    2013-01-01

    Full Text Available Biodegradable poly(L-lactic acid (PLLA/mesoporous silica nanocomposites were prepared by grafting L-lactic acid oligomer onto silanol groups at the surface of mesoporous silica (SBA-15. The infrared results showed that the lactic acid oligomer was grafted onto the mesoporous silica. Surface characterization of mesoporous silica proved that the grafted oligomer blocked the entry of nitrogen into the mesopores. Thermal analysis measurements showed evidence that, once mixed with PLLA, SBA-15 not only nucleated the PLLA but also increased the total amount of crystallinity. Neat PLLA and its nanocomposites crystallized in the same crystal habit and, as expected, PLLA had a defined periodicity compared with the nanocomposites. This was because the grafted macromolecules on silica tended to cover the lamellar crystalline order. The g-SBA-15 nanoparticles improved the tensile moduli, increasing also the tensile strength of the resultant nanocomposites. Overall, the silica concentration tended to form a brittle material.

  6. New Synthetic Methods and Structure-Property Relationships in Neptunium, Plutonium, and Americium Borates. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht-Schmitt, Thomas Edward

    2013-09-14

    The past three years of support by the Heavy Elements Chemistry Program have been highly productive in terms of advanced degrees awarded, currently supported graduate students, peer-reviewed publications, and presentations made at universities, national laboratories, and at international conferences. Ph.D. degrees were granted to Shuao Wang and Juan Diwu, who both went on to post-doctoral appointments at the Glenn T. Seaborg Center at Lawrence Berkeley National Laboratory with Jeff Long and Ken Raymond, respectively. Pius Adelani completed his Ph.D. with me and is now a post-doc with Peter C. Burns. Andrea Alsobrook finished her Ph.D. and is now a post-doc at Savannah River with Dave Hobbs. Anna Nelson completed her Ph.D. and is now a post-doc with Rod Ewing at the University of Michigan. As can be gleaned from this list, students supported by the Heavy Elements Chemistry grant have remained interested in actinide science after leaving my program. This follows in line with previous graduates in this program such as Richard E. Sykora, who did his post-doctoral work at Oak Ridge National Laboratory with R. G. Haire, and Amanda C. Bean, who is a staff scientist at Los Alamos National Laboratory, and Philip M. Almond and Thomas C. Shehee, who are both staff scientists at Savannah River National Laboratory, Gengbang Jin who is a staff scientist at Argonne National Lab, and Travis Bray who has been a post-doc at both LBNL and ANL. Clearly this program is serving as a pipe-line for students to enter into careers in the national laboratories. About half of my students depart the DOE complex for academia or industry. My undergraduate researchers also remain active in actinide chemistry after leaving my group. Dan Wells was a productive undergraduate of mine, and went on to pursue a Ph.D. on uranium and neptunium chalcogenides with Jim Ibers at Northwestern. After earning his Ph.D., he went directly into the nuclear industry.

  7. Structure-property relationship of ceramic coatings on metals produced by laser processing

    NARCIS (Netherlands)

    de Hosson, J.T.M.; van den Burg, M.; Mazumder, J; Conde, O; Villar, R; Steen, W

    1996-01-01

    This paper concentrates on the mechanical performance of various ceramic coatings of Cr2O3 on steel (SAF2205), as produced by CO2 laser processing. The thickness of the coating that can be applied by laser coating is limited to about 200 mu m setting a limit to the maximum strain energy release rate

  8. Prediction of Optimal Salinities for Surfactant Formulations Using a Quantitative Structure-Property Relationships Approach

    NARCIS (Netherlands)

    Muller, C.; Maldonado, A.G.; Varnek, A.; Creton, B.

    2015-01-01

    Each oil reservoir could be characterized by a set of parameters such as temperature, pressure, oil composition, and brine salinity, etc. In the context of the chemical enhanced oil recovery (EOR), the selection of high performance surfactants is a challenging and time-consuming task since this

  9. Structure-property relationships for n-alkyl-isocyanate-containing polymers

    Science.gov (United States)

    Aronson, Carl Lawrence

    Poly(n-hexyl isocyanate) (PHIC), poly(n-butyl-isocyanate) (PBIC), poly(n-butyl-co-cyclohexyl isocyanate) (PBCHIC), poly(n-hexyl isocyanate-b-isoprene) (HI), poly(n-butyl isocyanate-b-isoprene) (BI) and poly(n-hexyl isocyanate-b-isoprene- b-styrene) (MS) were synthesized and characterized with respect to composition, molecular Weight and polydispersity. PHIC, HI and HIS were found to be lyotropic liquid crystalline whereas PBIC, PBCHIC and BI were found to be non-lyotropic. A lyotropic-nematic liquid crystalline phase diagram was determined for the PHIC/xylene system. A novel and reversible electric-field-induced biphasic-paranematic phase transition was found for the PHIC/xylene system from the dynamics of topological defects. The electric-field-induced phase diagram for PHIC/xylene agreed with the theoretically predicted field-induced phase diagram of Khokhlov and Semenov for semiflexible-persistent polymers. The dielectric characteristics, steady-state electrically induced birefringence and steady-state electroheological (ER) activity of PHIC, PBIC and PBCHIC solutions were compared as a function of polymer concentration. The role of lyotropic liquid crystalline ordering in the functional ER mechanism of poly( n-hexyl isocyanate) solutions is presented. PBCHIC was found to thermally decompose by a first-order rate process which became slower with increasing cyclohexyl isocyanate content from thermal gravimetric analysis. Competition between monomer dissociation and degradative trimerization as well as a non-alternating sequence distribution were determined for PBCHIC from direct pyrolysis/mass spectrometry. The Arrhenius activation energy, pre-exponential factor and entropy for diffusion and evaporation of xylene from PHIC, were found to be functions of initial polymer concentration whereas the intrinsic diffusion coefficient of the solvent was found to be independent of initial polymer concentration. The cross polarized/magic angle spinning solid state 13C-NMR spectra of PBCHIC revealed perturbations to the helical polymer backbone structure. The wide angle x-ray diffraction pattern for the n-hexyl isocyanate containing polymers was found to be a function of DC electric field strength applied during isothermal crystallization from solution. The PHIC, backbone was protonated on a small percentage of monomer units by reaction with BF3 and H2O with no detectable chain scission but a loss of lyotropic liquid crystallinity. Methyl-N-(1,1-dimetboxyperfluroro- n-heptyl)carbamate was isolated from the reaction of perfluoro- n-heptyl isocyanate with excess methanol. 2,5-Dioxahexyl isocyanate and 2,5,8-trioxanonyl isocyanate were synthesized.

  10. Understanding nanocellulose chirality and structure-properties relationship at the single fibril level

    Science.gov (United States)

    Usov, Ivan; Nyström, Gustav; Adamcik, Jozef; Handschin, Stephan; Schütz, Christina; Fall, Andreas; Bergström, Lennart; Mezzenga, Raffaele

    2015-06-01

    Nanocellulose fibrils are ubiquitous in nature and nanotechnologies but their mesoscopic structural assembly is not yet fully understood. Here we study the structural features of rod-like cellulose nanoparticles on a single particle level, by applying statistical polymer physics concepts on electron and atomic force microscopy images, and we assess their physical properties via quantitative nanomechanical mapping. We show evidence of right-handed chirality, observed on both bundles and on single fibrils. Statistical analysis of contours from microscopy images shows a non-Gaussian kink angle distribution. This is inconsistent with a structure consisting of alternating amorphous and crystalline domains along the contour and supports process-induced kink formation. The intrinsic mechanical properties of nanocellulose are extracted from nanoindentation and persistence length method for transversal and longitudinal directions, respectively. The structural analysis is pushed to the level of single cellulose polymer chains, and their smallest associated unit with a proposed 2 × 2 chain-packing arrangement.

  11. Structure-property relationships in flavour-barrier membranes with reduced high-temperature diffusivity

    International Nuclear Information System (INIS)

    Heitfeld, Kevin A.; Schaefer, Dale W.

    2009-01-01

    Encapsulation is used to decrease the premature release of volatile flavour ingredients while offering protection against environmental damage such as oxidation, light-induced reactions, etc. Hydroxypropyl cellulose (HPC) is investigated here as a 'smart,' temperature responsive membrane for flavour encapsulation and delivery. Gel films were synthesized and characterized by diffusion and small-angle neutron and X-ray scattering techniques. Increasing temperature typically increases the diffusion rate across a membrane; HPC, however, can be tailored to give substantially improved elevated temperature properties. Scattering results indicate processing conditions have a significant impact on membrane morphology (micro phase separation). Under certain synthetic conditions, micro phase separation is mitigated and the membranes show temperature-independent diffusivity between 25 C and 60 C.

  12. Structure Property Relationship of Suspension Thermally Sprayed WC-Co Nanocomposite Coatings

    Science.gov (United States)

    Ahmed, R.; Faisal, N. H.; Al-Anazi, Nayef M.; Al-Mutairi, S.; Toma, F.-L.; Berger, L.-M.; Potthoff, A.; Polychroniadis, E. K.; Sall, M.; Chaliampalias, D.; Goosen, M. F. A.

    2015-02-01

    Tribomechanical properties of nanostructured coatings deposited by suspension high velocity oxy-fuel (S-HVOF) and conventional HVOF (Jet Kote) spraying were evaluated. Nanostructured S-HVOF coatings were obtained via ball milling of the agglomerated and sintered WC-12Co feedstock powder, which were deposited via an aqueous-based suspension using modified HVOF (TopGun) process. Microstructural evaluations of these hardmetal coatings included transmission electron microscopy, x-ray diffraction, and scanning electron microscopy equipped with energy dispersive x-ray spectroscopy. The nanohardness and modulus of the coated specimens were investigated using a diamond Berkovich nanoindenter. Sliding wear tests were conducted using a ball-on-flat test rig. Results indicated that low porosity coatings with nanostructured features were obtained. High carbon loss was observed, but coatings showed a high hardness up to 1000 HV2.9N. S-HVOF coatings also showed improved sliding wear and friction behavior, which were attributed to nanosized particles reducing ball wear in three-body abrasion and support of metal matrix due to uniform distribution of nanoparticles in the coating microstructure.

  13. Forest evaporation models: Relationships between stand growth and evaporation

    CSIR Research Space (South Africa)

    Le Maitre, David C

    1997-06-01

    Full Text Available The relationships between forest stand structure, growth and evaporation were analysed to determine whether forest evaporation can be estimated from stand growth data. This approach permits rapid assessment of the potential impacts of afforestation...

  14. Structural properties of CrN buffers for GaN growth

    International Nuclear Information System (INIS)

    Lee, W. H.; Im, I. H.; Minegishi, T.

    2006-01-01

    We have investigated the structural properties of CrN layers grown on (0001) Al 2 O 3 substrates by molecular-beam epitaxy. The CrN layers of high-crystal quality are obtained at a low growth temperature of 500 .deg. C. X-ray diffraction studies indicate that the CrN layers grow along the direction with a cubic structure. In-situ reflection high-energy electron diffraction investigations clarify that the CrN layers have the following epitaxy relationship with the Al 2 O 3 substrates: of (111) cubic CrN // of (0001) corundum Al 2 O 3 and of (111) cubic CrN // of (0001) corundum Al 2 O 3 . Based on the above results, the mismatch of the in-plane lattice spacing between the CrN layers and the Al 2 O 3 substrates is evaluated to be around 6.6 %. When the CrN layers are used as the buffer layers for GaN growth, the GaN layers grown on the CrN layers show well-resolved excitonic emission lines in the photoluminescence spectra, whereas the GaN layers grown without the CrN layers exhibit a broad near-band-edge emission. It is suggested that CrN buffers are effective in relieving the lattice mismatch between Al 2 O 3 substrates and GaN layers.

  15. Structural properties governing drug-plasma protein binding determined by high-performance liquid chromatography method.

    Science.gov (United States)

    Kamble, Sharad; Loadman, Paul; Abraham, Michael H; Liu, Xiangli

    2018-02-05

    The high-performance liquid chromatography (HPLC) method employing stationary phases immobilized with plasma proteins was used for this study to investigate the structural properties governing drug-plasma protein binding. A set of 65 compounds with a broad range of structural diversity (in terms of volume, hydrogen-bonding, polarity and electrostatic force) were selected for this purpose. The Abraham linear free energy relationship (LFER) analyses of the retention factors on the immobilized HSA (human serum albumin) and AGP (α 1 -acid glycoprotein) stationary phases showed that McGowan's characteristic molecular volume (V), dipolarity/polarizability (S) and hydrogen bond basicity (B) are the three significant molecular descriptors of solutes determining the interaction with immobilized plasma proteins, whereas excess molar refraction (E) is less important and hydrogen bond acidity (A) is not of statistical significance in both systems, for electrically neutral compounds. It was shown that ionised acids, as carboxylate anions, bind very strongly to the immobilized HSA stationary phase and that ionised bases, as cations bind strongly to the AGP stationary phase. This is the first time that the effect of ionised species on plasma protein binding has been determined quantitatively; the increased binding of acids to HSA is due almost entirely to acids in their ionised form. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Remaining in an Abusive Relationship: An Investment Model Analysis of Nonvoluntary Dependence.

    Science.gov (United States)

    Rusbult, Caryl E.; Martz, John M.

    1995-01-01

    Analyzes the nature of interdependence in ongoing relationships, using an investment model to understand decisions to remain in abusive relationships. Found that feelings of commitment were greater among women who had poorer-quality economic alternatives, were more heavily invested in their relationship, and who experienced less dissatisfaction…

  17. Inequity in work and intimate relationships: a Spillover-Crossover model.

    Science.gov (United States)

    Bakker, Arnold B; Petrou, Paraskevas; Tsaousis, Ioannis

    2012-01-01

    This study among 267 Greek teachers and their partners tested and expanded the recently proposed Spillover-Crossover model (SCM) of well-being. Accordingly, experiences built up at work spill over to the home domain, and then influence the partner. The authors integrated equity theory in the model by formulating hypotheses about exchange in interpersonal relationships. Structural equation modeling analyses supported the spillover hypothesis that teachers who lose their work engagement as a result of an inequitable relationship with their students invest less in the relationship with their partner. In addition, the results supported the crossover hypothesis that teachers' relationship investments, in turn, show a negative relationship with inequity in the intimate relationship as perceived by the partner; and inequity in the intimate relationship contributed to partner depression. The findings are discussed in light of the SCM of well-being.

  18. Geometrical Modeling of Woven Fabrics Weavability-Limit New Relationships

    Directory of Open Access Journals (Sweden)

    Dalal Mohamed

    2017-03-01

    Full Text Available The weavability limit and tightness for 2D and 3D woven fabrics is an important factor and depends on many geometric parameters. Based on a comprehensive review of the literature on textile fabric construction and property, and related research on fabric geometry, a study of the weavability limit and tightness relationships of 2D and 3D woven fabrics was undertaken. Experiments were conducted on a representative number of polyester and cotton woven fabrics which have been woven in our workshop, using three machines endowed with different insertion systems (rapier, projectiles and air jet. Afterwards, these woven fabrics have been analyzed in the laboratory to determine their physical and mechanical characteristics using air permeability-meter and KES-F KAWABATA Evaluation System for Fabrics. In this study, the current Booten’s weavability limit and tightness relationships based on Ashenhurst’s, Peirce’s, Love’s, Russell’s, Galuszynskl’s theory and maximum-weavability is reviewed and modified as new relationships to expand their use to general cases (2D and 3D woven fabrics, all fiber materiel, all yarns etc…. The theoretical relationships were examined and found to agree with experimental results. It was concluded that the weavability limit and tightness relationships are useful tools for weavers in predicting whether a proposed fabric construction was weavable and also in predicting and explaining their physical and mechanical properties.

  19. Towards modelling of human relationships:nonlinear dynamical systems in relationships

    OpenAIRE

    Safarov, I. (Ildar)

    2009-01-01

    Abstract This study fills an urgent need for qualitative analyses of relationships resulting in human change. It is a result of sixteen years of independent study by the author. It combines postgraduate study of nonlinear methodology, applied research of children’s pretend play, experience in educational psychology and Gestalt-counselling, as well as the practical training of graduate students at the Karelian State Pedagogical University (Petrozavodsk, Russia), and the Kajaani Department ...

  20. Relationship between Business Strategy and Business Model Studied in a Sample of Service Companies

    Directory of Open Access Journals (Sweden)

    Slávik Štefan

    2016-12-01

    Full Text Available A business model and a business strategy are the basic conditions of a company existence. A business model describes and explains how a company works and makes money. A business strategy describes and explains how, where and for what purpose and goal a business model will be used. The research seeks to ascertain whether there is any measurable relationship between a strategy and a model. An identification of this relationship will deepen knowledge of strategic management of the company and it is a reason for further research on the nature of relationship between a model and a strategy.

  1. The Soul Mates Model: A Seven-Stage Model for Couple's Long-Term Relationship Development and Flourishing

    Science.gov (United States)

    De La Lama, Luisa Batthyany; De La Lama, Luis; Wittgenstein, Ariana

    2012-01-01

    This article presents the integrative soul mates relationship development model, which provides the helping professionals with a conceptual map for couples' relationship development from dating, to intimacy, to soul mating, and long-term flourishing. This model is informed by a holistic, a developmental, and a positive psychology conceptualization…

  2. Using fuzzy models to migrate from customer relationship management (CRM) to customer experience management (CEM)

    OpenAIRE

    Dr. Anna Maria Gil-Lafuente; Carolina Luis-Bassa

    2011-01-01

    Relationship Marketing has made rapid progress during the last ten years. Since the development of the customer-centric model, reinforced by the emergence of CRM (Customer Relationship Management) strategies, companies have focused on finding models and tools that allow them to get to know better their clients. The management of customer relationship with the company has evolved from seeking the customer satisfaction to seek customer loyalty, and later on to create a brand advocate consumer f...

  3. The Force-Frequency Relationship: Insights from Mathematical Modeling

    Science.gov (United States)

    Puglisi, Jose L.; Negroni, Jorge A.; Chen-Izu, Ye; Bers, Donald M.

    2013-01-01

    The force-frequency relationship has intrigued researchers since its discovery by Bowditch in 1871. Many attempts have been made to construct mathematical descriptions of this phenomenon, beginning with the simple formulation of Koch-Wesser and Blinks in 1963 to the most sophisticated ones of today. This property of cardiac muscle is amplified by…

  4. A Socio-Cultural Model Based on Empirical Data of Cultural and Social Relationship

    DEFF Research Database (Denmark)

    Lipi, Afia Akhter; Nakano, Yukiko; Rehm, Matthias

    2010-01-01

    The goal of this paper is to integrate culture and social relationship as a computational term in an embodied conversational agent system by employing empirical and theoretical approach. We propose a parameter-based model that predicts nonverbal expressions appropriate for specific cultures...... with empirical data, we establish a parameterized network model that generates culture specific non-verbal expressions in different social relationships....

  5. Maternal Working Models of Attachment, Marital Adjustment, and the Parent-Child Relationship.

    Science.gov (United States)

    Eiden, Rina Das; And Others

    1995-01-01

    Examined the connection between maternal working models, marital adjustment, and parent-child relationship among 45 mothers and their 16- to 62-month-old children. Found that maternal working models were related to the quality of mother-child interactions and child security, as well as a significant relationship between marital adjustment and…

  6. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    also increases such properties. Yet, these rules are not strictly followed even for the simplest binary oxide glasses, such as alkali silicates, borates and phosphates. In this thesis it is argued that the missing link between composition and properties is the glass structure. Structural models...... are proposed based on topological selection rules and experimentally verified. The relation between structure and properties is evaluated using topological constraint theory, which in its essence is a theory that quantifies the two intuitions of the glass scientist. The end result is a quantitative model...

  7. Adolescents' working models and styles for relationships with parents, friends, and romantic partners.

    Science.gov (United States)

    Furman, Wyndol; Simon, Valerie A; Shaffer, Laura; Bouchey, Heather A

    2002-01-01

    This study examined the links among adolescents' representations of their relationships with parents, friends, and romantic partners. Sixty-eight adolescents were interviewed three times to assess their working models for each of these types of relationships. Working models of friendships were related to working models of relationships with parents and romantic partners. Working models of relationships with parents and romantic partners were inconsistently related. A similar pattern of results was obtained for self-report measures of relational styles for the three types of relationships. Perceived experiences were also related. Specifically, support in relationships with parents tended to be related to support in romantic relationships and friendships, but the latter two were unrelated. On the other hand, self and other controlling behaviors in friendships were related to corresponding behaviors in romantic relationships. Negative interactions in the three types of relationships also tended to be related. Taken together, the findings indicate that the representations of the three types of relationships are distinct, yet related. Discussion focuses on the nature of the links among the three.

  8. Structural properties of low-density liquid alkali metals

    Indian Academy of Sciences (India)

    The static structure factors of liquid alkali metals have been modelled at temperatures close to their melting points and a few higher temperatures using the reverse Monte Carlo (RMC) method. The positions of 5000 atoms in a box, with full periodicity, were altered until the experimental diffraction data of the structure factor ...

  9. Relationship Model of Personality, Communication, Student Engagement, and Learning Satisfaction

    Directory of Open Access Journals (Sweden)

    Dorothea Ariani

    2015-12-01

    Full Text Available This study aims to examine the engagement as a mediating variable of the relationship between personality and communication with satisfaction. This study was conducted at business school in Indonesia with 307 students who are still active as a respondent. Survey research was conducted over four months by questionnaire that has been well-established that was taken and modified from previous studies. The results of this study indicate that student engagement mediates the relationship between personality and communication as independent variables and satisfaction as the dependent variable. Extroversion personality and communication significantly positive effect on student engagement in all three dimensions (vigor, dedication, and absorption. In addition, this study also showed that engagement and satisfaction are two different variables, but correlated, and there was no difference in terms of gender differences involvement.

  10. Distensibility and pressure-flow relationship of the pulmonary circulation. I. Single-vessel model.

    Science.gov (United States)

    Bshouty, Z; Younes, M

    1990-04-01

    To ascertain the relative contributions of vascular distensibility and nonhomogeneous behavior within the pulmonary circulation to the distinctive nonlinear relationship between inflow pressure (Pin) and flow [pressure-flow (P-F) relationship] and between Pin and outflow pressure (Pout) at constant flow (Pin-Pout relationship), we developed a multibranched model in which the elastic behavior of, and forces acting on, individual branches can be varied independently. The response of the multibranched model is described in the companion article (J. Appl. Physiol. 68: 1514-1527, 1990). Here we describe the methods used and the responses of single components of the larger model. Perivascular pressure is modeled as a function of intravascular and transpulmonary pressures (Pv and Ptp, respectively) and vessel length as a function of lung volume. These and the relationship between vascular area (A) and transmural pressure (Ptm) were modeled primarily from the dog data of Smith and Mitzner (J. Appl. Physiol. 48: 450-467, 1980). Vasomotor tone is modeled as a radial collapsing pressure (Pt) in the same plane as Ptm. In view of lack of information about the relationship between Pt and A for a given active state, different patterns were assumed that span a wide range of possible relationships. The P-F and Pin-Pout relationships of single vessels were very similar to those reported for the entire intact circulation. Of note, the slope of the Pin-Pout relationship in the low Pout range (0-5 Torr) was very low (less than 0.25) and increased gradually with Pout toward unity. Vasomotor tone caused an apparent parallel shift in the P-F relationship in the physiological flow range of the dog (2-8 l/min) regardless of the pattern used to model the Pt vs. A relationship; different patterns affected the P-F relationship only over the low flow range before the parallel shift was established.

  11. Identifying and Evaluating the Relationships that Control a Land Surface Model's Hydrological Behavior

    Science.gov (United States)

    Koster, Randal D.; Mahanama, Sarith P.

    2012-01-01

    The inherent soil moisture-evaporation relationships used in today 's land surface models (LSMs) arguably reflect a lot of guesswork given the lack of contemporaneous evaporation and soil moisture observations at the spatial scales represented by regional and global models. The inherent soil moisture-runoff relationships used in the LSMs are also of uncertain accuracy. Evaluating these relationships is difficult but crucial given that they have a major impact on how the land component contributes to hydrological and meteorological variability within the climate system. The relationships, it turns out, can be examined efficiently and effectively with a simple water balance model framework. The simple water balance model, driven with multi-decadal observations covering the conterminous United States, shows how different prescribed relationships lead to different manifestations of hydrological variability, some of which can be compared directly to observations. Through the testing of a wide suite of relationships, the simple model provides estimates for the underlying relationships that operate in nature and that should be operating in LSMs. We examine the relationships currently used in a number of different LSMs in the context of the simple water balance model results and make recommendations for potential first-order improvements to these LSMs.

  12. DESIGNING A MODEL OF CUSTOMER RELATIONSHIP MANAGEMENT FOR A MOBILE PHONE COMPANY

    Directory of Open Access Journals (Sweden)

    BRUTU MĂDĂLINA

    2015-07-01

    Full Text Available Customer relationship management refers to establishing, maintaining, developing and optimizing the relations between an organization and its customers and focuses on understanding and meeting its customers’ wishes and demands, the core items of the business strategy of any performant company. This paper aims at designing and testing a model of customer relationship management applicable within a mobile phone company. Starting from this purpose, the main objectives of the research were: presenting the concept of customer relationship management; the importance of companies’ orientation to the market; identifying a model of customer relationship management and, not least, analyzing the efficiency of this model. The results lead to the conclusion that the model of customer relationship management is extremely effective in the mobile phone industry, bringing significant profits.

  13. The Exploration of the Relationship between Guessing and Latent Ability in IRT Models

    Science.gov (United States)

    Gao, Song

    2011-01-01

    This study explored the relationship between successful guessing and latent ability in IRT models. A new IRT model was developed with a guessing function integrating probability of guessing an item correctly with the examinee's ability and the item parameters. The conventional 3PL IRT model was compared with the new 2PL-Guessing model on…

  14. A Comparative Structural Equation Modeling Investigation of the Relationships among Teaching, Cognitive and Social Presence

    Science.gov (United States)

    Kozan, Kadir

    2016-01-01

    The present study investigated the relationships among teaching, cognitive, and social presence through several structural equation models to see which model would better fit the data. To this end, the present study employed and compared several different structural equation models because different models could fit the data equally well. Among…

  15. Structural properties of hard disks in a narrow tube

    International Nuclear Information System (INIS)

    Varga, S; Gurin, P; Balló, G

    2011-01-01

    Positional ordering of a two-dimensional fluid of hard disks is examined in tubes so narrow that only nearest neighbor interactions take place. Using the exact transfer-matrix method the transverse and longitudinal pressure components and the correlation function are determined numerically. Fluid–solid phase transition does not occur even in the widest tube, where the method just loses its exactness, but the appearance of a dramatic change in the equation of state and the longitudinal correlation function shows that the system undergoes a structural change from a fluid to a solid-like order. The pressure components show that the collisions are dominantly longitudinal at low densities, while they are transverse in the vicinity of the close packing density. The transverse correlation function shows that the size of solid-like domains grows exponentially with increasing pressure and the correlation length diverges at close packing. It is possible to find an analytically solvable model by expanding the contact distance up to first order. The approximate model, which corresponds to a system of hard parallel rhombuses, behaves very similarly to the system of hard disks

  16. Negative childhood experiences and adult love relationships: the role of internal working models of attachment.

    Science.gov (United States)

    McCarthy, Gerard; Maughan, Barbara

    2010-09-01

    This study investigated links between internal working models of attachment and the quality of adult love relationships in a high risk sample of women (n = 34), all of whom reported negative parenting in childhood. Half of the sample was identified as having a history of satisfying adult love relationships, while the remainder had experienced ongoing adult relationship problems. Measures of internal working models of attachment were made using the Adult Attachment Interview (AAI). A strong association was found between attachment classifications and the quality of adult love relationships. In addition, women with satisfying love relationships demonstrated significantly higher coherence of mind ratings than those with poor relationship histories. Insecure working models of attachment were associated with problems in adult love relationships. Although secure/autonomous attachment status was linked to optimal adult relationship outcomes, some women with a history of satisfying love relationships had insecure working models of attachment. These results suggest that the ways that adults process early experiences may influence later psychosocial functioning.

  17. Exploring the Relationship between Mathematical Modelling and Classroom Discourse

    Science.gov (United States)

    Redmond, Trevor; Sheehy, Joanne; Brown, Raymond

    2010-01-01

    This paper explores the notion that the discourse of the mathematics classroom impacts on the practices that students engage when modelling mathematics. Using excerpts of a Year 12 student's report on modelling Newton's law of cooling, this paper argues that when students engage with the discourse of their mathematics classroom in a manner that…

  18. Electron momentum density, band structure, and structural properties of SrS

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, G., E-mail: gsphysics@gmail.com [University of Kota, Department of Pure and Applied Physics (India); Munjal, N.; Vyas, V. [Banasthali University, Department of Physics (India); Kumar, R.; Sharma, B. K. [University of Rajasthan, Department of Physics (India); Joshi, K. B. [MLS University, Department of Physics (India)

    2013-10-15

    The electron momentum density, the electronic band structure, and the structural properties of SrS are presented in this paper. The isotropic Compton profile, anisotropies in the directional Compton profiles, the electronic band structure and density of states are calculated using the ab initio periodic linear combination of atomic orbitals method with the CRYSTAL06 code. Structural parameters of SrS-lattice constants and bulk moduli in the B1 and B2 phases-are computed together with the transition pressure. The computed parameters are well in agreement with earlier investigations. To compare the calculated isotropic Compton profile, measurement on polycrystalline SrS is performed using 5Ci-{sup 241}Am Compton spectrometer. Additionally, charge transfer is studied by means of the Compton profiles computed from the ionic model. The nature of bonding in the isovalent SrS and SrO compounds is compared on the basis of equal-valenceelectron-density profiles and the bonding in SrS is found to be more covalent than in SrO.

  19. Revisiting the Relationship Between Data, Models, and Decision-Making.

    Science.gov (United States)

    Ferré, Ty P A

    2017-09-01

    We hydrologists can do a better job of supporting water-resources decision-making. I will argue that we can do this by recognizing that decision makers use qualitative, multiple-narrative approaches. So, rather than providing single-model predictions with quantitative uncertainties, we should develop teams of rival models that inform decision makers about what is known, what is possible, and what is unknown. This requires that we build ensembles of models that include biased, advocacy models that directly represent stakeholders' interests or concerns. From this inclusive platform, we can speak objectively and clearly about the risks that drive stakeholders' decisions. Furthermore, we will be promoting more appropriate use of the scientific method in making informed water-resources decisions. © 2017, National Ground Water Association.

  20. Adhesive and structural properties of thermoreversible polyacrylate gels

    Science.gov (United States)

    Flanigan, Cynthia Mowery

    Methods for quantifying very weak adhesive interactions between two bodies in contact have been developed using a low-modulus material in conjunction with a linear elastic fracture mechanics analysis based on the treatment of Johnson, Kendall and Roberts (JKR). Using this approach, axisymmetric adhesion tests have been performed on polyacrylate gel lenses and thin layers, in contact with well-characterized surfaces. These thermally reversible gels were formed by diluting a triblock copolymer with poly(methyl methacrylate) (PMMA) endblocks and a poly(n-butyl acrylate) midblock with a selective solvent for the center block. Rheological studies on this swollen copolymer indicate that the material is completely elastic at room temperature and undergoes a rapid, thermally reversible gelation, thus making it an excellent model system to probe the adhesive properties of soft materials. Adhesive and frictional properties of thin, elastic layers in contact with a glass, hemispherical indenter have been investigated. Studies on these highly compliant gels highlight the significance of finite size corrections to the compliance and displacement between the two contacting bodies. For situations where the applied load is too low to measure experimentally, expressions for G /E, the energy release rate normalized by Young's modulus, are shown to provide an accurate means to quantify adhesion with these low-moduli materials. Small angle X-ray scattering experiments in conjunction with rheological tests have shown that changes in composition and temperature affect the elastic nature of the gel. In addition, an equilibrium gelation process is utilized to produce "dried" polymer layers with reproducible adhesive properties. With this method, acrylic acid moieties have been shown to enhance the adhesive performance of these materials without influencing their structure. Lastly, the development of elastic instabilities within confined gel layers has been examined. The aspect ratio of

  1. A Comparative Study of Successful Central Nervous System Drugs Using Molecular Modeling

    Science.gov (United States)

    Kim, Hyosub; Sulaimon, Segun; Menezes, Sandra; Son, Anne; Menezes, Warren J. C.

    2011-01-01

    Molecular modeling is a powerful tool used for three-dimensional visualization and for exploring electrostatic forces involved in drug transport. This tool enhances student understanding of structure-property relationships, as well as actively engaging them in class. Molecular modeling of several central nervous system (CNS) drugs is used to…

  2. EMF 7 model comparisons: key relationships and parameters

    Energy Technology Data Exchange (ETDEWEB)

    Hickman, B.G.

    1983-12-01

    A simplified textbook model of aggregate demand and supply interprets the similarities and differences in the price and income responses of the various EMF 7 models to oil and policy shocks. The simplified model is a marriage of Hicks' classic IS-LM formulation of the Keynesian theory of effective demand with a rudimentary model of aggregate supply, combining a structural Phillips curve for wage determination and a markup theory of price determination. The reduced-form income equation from the fix-price IS-LM model is used to define an aggregate demand (AD) locus in P-Y space, showing alternative pairs of the implicit GNP deflator and real GNP which would simultaneously satisfy the saving-investment identity and the condition for money market equilibrium. An aggregate supply (AS) schedule is derived by a similar reduction of relations between output and labor demand, unemployment and wage inflation, and the wage-price-productivity nexus governing markup pricing. Given a particular econometric model it is possible to derive IS and LM curves algebraically. The resulting locuses would show alternative combinations of interest rate and real income which equilibrate real income identity on the IS side and the demand and supply of money on the LM side. By further substitution the reduced form fix-price income relation could be obtained for direct quantification of the AD locus. The AS schedule is obtainable by algebraic reduction of the structural supply side equations.

  3. Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network

    OpenAIRE

    Kwok, Jeremy Jie Ming; Lee, Dong-Yup

    2015-01-01

    Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on ...

  4. Structural properties of laminated Douglas fir/epoxy composite material

    Energy Technology Data Exchange (ETDEWEB)

    Spera, D.A. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center); Esgar, J.B. (Sverdrup Technology, Inc., Cleveland, OH (USA)); Gougeon, M.; Zuteck, M.D. (Gougeon Bros., Bay City, MI (USA))

    1990-05-01

    This publication contains a compilation of static and fatigue and strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 in. by 24 in. in cross section and approximately 30 ft long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications. 9 refs.

  5. Adapting the Interpersonal Process Model of Intimacy to Enhance the Co-Leader Relationship during Training

    Science.gov (United States)

    Huffman, David D.; Fernando, Delini M.

    2012-01-01

    Group work literature acknowledges that the group co-leader relationship influences the development of group members and the group as a whole. However, little direction has been offered for supervisors of group co-leaders to facilitate the development of the co-leader relationship. Reis and Shaver's (1988) interpersonal process model of intimacy…

  6. Data-Model Relationship in Text-Independent Speaker Recognition

    Directory of Open Access Journals (Sweden)

    Stapert Robert

    2005-01-01

    Full Text Available Text-independent speaker recognition systems such as those based on Gaussian mixture models (GMMs do not include time sequence information (TSI within the model itself. The level of importance of TSI in speaker recognition is an interesting question and one addressed in this paper. Recent works has shown that the utilisation of higher-level information such as idiolect, pronunciation, and prosodics can be useful in reducing speaker recognition error rates. In accordance with these developments, the aim of this paper is to show that as more data becomes available, the basic GMM can be enhanced by utilising TSI, even in a text-independent mode. This paper presents experimental work incorporating TSI into the conventional GMM. The resulting system, known as the segmental mixture model (SMM, embeds dynamic time warping (DTW into a GMM framework. Results are presented on the 2000-speaker SpeechDat Welsh database which show improved speaker recognition performance with the SMM.

  7. Structural properties and elasticity of amphiphilics on water

    Science.gov (United States)

    Daillant, J.; Bosio, L.; Harzallah, B.; Benattar, J. J.

    1991-02-01

    Monolayers of amphiphilic molecules adsorbed at the air-water interface have been studied using X-ray reflectivity. This technique allows an accurate and independent determination of thicknesses (by the measurement of fringes of equal inclination) as well as densities and roughnesses (since this is an absolute intensity measurement); therefore a complete electron density profile can be obtained. The surface roughness is due to thermally excited capillary waves, and is thus related to the dynamics of the interface, which are conditionned by the elastic constants of the layer. The phase diagrams of the C{15}, C{21} and C{29} fatty acids and of the phospholipid L-α-DPPC have been investigated using this method, and an analysis of the phase transitions has been performed. From the structural point of view, a general feature of this class of compounds adsorbed on water is an unchanging aliphatic medium density within the liquid and solid phases. If follows that the pressure vs. film thickness curves mimic the pressure area curves. In particular evidence for the liquid-expanded to liquid-condensed transition is given by an abrupt increase of the aliphatic medium thickness. The data suggest that this transition should involve conformational changes. Furthermore the decrease in molecular area within the liquid condensed phase is revealed by a decreasing molecular tilt angle. The structure of this phase is also shown to be independent of the temperature and of the nature of the polar head-group. A transition to a multilayer structure is observed with the longest chain compound. We show that the dynamics of the interface are consistent in the liquid phases with a simple capillary wave model, with no adjustable parameter. A strong drop in the roughness at the transition to the solid state reveals the onset of a rigidity against bending. The high values of the rigidity modulus obtained (on the order of 100 k_B T) are sensitive to the aliphatic chain length and can be

  8. Strategic Engagement: New Models of Relationship Management for Academic Librarians

    Science.gov (United States)

    Eldridge, Jeanette; Fraser, Katie; Simmonds, Tony; Smyth, Neil

    2016-01-01

    How do we best bridge the gap between the Library and the diverse academic communities it serves? Librarians need new strategies for engagement. Traditional models of liaison, aligning solutions to disciplines, are yielding to functional specialisms, including a focus on building partnerships. This paper offers a snapshot of realignment across the…

  9. Reappraising the Relationships between Physics Students' Mental Models and Predictions: An Example of Heat Convection

    Science.gov (United States)

    Chiou, Guo-Li

    2013-01-01

    Although prediction is claimed to be a prime function of mental models, to what extent students can run their mental models to make predictions of physical phenomena remains uncertain. The purpose of this study, therefore, was first to investigate 30 physics students' mental models of heat convection, and then to examine the relationship between…

  10. THE RELATIONSHIP BETWEEN MODELS OF QUALITY MANAGEMENT AND CSR

    Directory of Open Access Journals (Sweden)

    CĂTĂLINA SITNIKOV

    2015-03-01

    Full Text Available Lately, the quality management has integrated more and more among its components Corporate Social Responsibility (CSR. With strong roots in the foundation for sustainable development, protection of the environment, issues of social justness and economic growth, CSR raises numerous issues related to obtaining profits, business performance and firms and activities based on the quality of management. From the point of view of the last issues, the models of quality management built on the fundamental principles of quality become the foundation and catalyst for the effective implementation of CSR in organizations. This is the reason why it is necessary to investigate the extent to which quality management models provide frameworks and guidelines for integrating CSR in the management of quality and, moreover, in the management of the organization, with a clear focus on the extent to which the concept can be institutionalized and operated by the organization.

  11. A new model for the body size-metabolism relationship.

    Science.gov (United States)

    Roberts, Michael F; Lightfoot, Edwin N; Porter, Warren P

    2010-01-01

    The allometric 3/4 power relation, initially used for describing the relation between mammalian basal metabolic rate and body size, is often used as a general model for organismal design. The use of allometric regression as a model has important limitations: it is not mechanistic, it combines all physiological variables into one correlate of body size, and it combines data from several physiological states. In reassessing the use of allometric equations, we first describe problems with their use in studies of organismal design and then use a formulation for distributed net heat production and temperature distribution within the body to derive an alternative equation for the relation between basal metabolism and body size. Tests of the heat flow equation against data reported in the literature indicate that it is an accurate estimator of basal metabolism under thermoneutral conditions and suggest that the allometric equation is a special case of this mechanistic and more general model. We propose that our method is more meaningful and widely applicable for thermoneutral conditions than is a purely allometric approach.

  12. A study of SEC chromatograms on the basis of polymer structure properties

    DEFF Research Database (Denmark)

    already been well established, while for nonlinear polymer samples and mixtures of linear and nonlinear polymers, the measured SEC data are often used just qualitatively. The SEC separation process is rather complicated, and a detailed study using finite element method and/or Brownian Dynamics simulation...... curve may exist between the SEC retention volume and polymer structure properties such as hydrodynamic volume, hydrodynamic radius and radius of gyration. Those structure properties can be determined by intrinsic viscosity measurement, dynamic and static light scattering respectively, and the measured...

  13. NONPARAMETRIC FIXED EFFECT PANEL DATA MODELS: RELATIONSHIP BETWEEN AIR POLLUTION AND INCOME FOR TURKEY

    Directory of Open Access Journals (Sweden)

    Rabia Ece OMAY

    2013-06-01

    Full Text Available In this study, relationship between gross domestic product (GDP per capita and sulfur dioxide (SO2 and particulate matter (PM10 per capita is modeled for Turkey. Nonparametric fixed effect panel data analysis is used for the modeling. The panel data covers 12 territories, in first level of Nomenclature of Territorial Units for Statistics (NUTS, for period of 1990-2001. Modeling of the relationship between GDP and SO2 and PM10 for Turkey, the non-parametric models have given good results.

  14. Converting round tendons to flat tendon constructs: Does the preparation process have an influence on the structural properties?

    Science.gov (United States)

    Domnick, C; Herbort, M; Raschke, M J; Schliemann, B; Siebold, R; Śmigielski, R; Fink, C

    2017-05-01

    The structural properties of hamstring tendon grafts were evaluated in a porcine model, after processing it to a flat shape, to better replace or augment anatomic flat structures (e.g. ACL, MPFL or MCL). In this biomechanical study, porcine flexor tendons were used which have a comparable shape to semitendinosus and gracilis tendons. One part of the tendon was prepared to a flat tendon construct by splitting the tendon longitudinally with a knife to half of the diameter of the tendon. The semi-split tendon was scratched out to a flat shape. The other matched part was tested in its original round shape. The tendons (n = 40) have been fixed in a uniaxial testing machine (Zwick/Roell) by cryo-clamps after preparing the fixed ends by 2-0 polyester sutures (2-0 Ethibond ® EXCEL, Ethicon, Somerville, NJ). In every specimen, there was a free 60-mm tendon part between both clamps. The tendons have been loaded to failure to evaluate typical biomechanical parameters such as stiffness, yield load and maximum load. No statistically significant differences (n.s.) regarding stiffness, yield load and maximum load between natively round and processed flat tendons could be detected. A prepared flat-shaped tendon does not show any different structural properties compared with an original round tendon. Therefore, a flat tendon seems to be a biomechanical stable graft option for anatomic reconstruction or augmentation of injured natively flat-shaped structures such as MCL, MPFL or ACL.

  15. Structure-property-processing correlations in freeze-cast composite scaffolds.

    Science.gov (United States)

    Hunger, Philipp M; Donius, Amalie E; Wegst, Ulrike G K

    2013-05-01

    Surprisingly few reports have been published, to date, on the structure-property-processing correlations observed in freeze-cast materials directionally solidified from polymer solutions, or ceramic or metal slurries. The studies that exist focus on properties of sintered ceramics, that is materials whose structure was altered by further processing. In this contribution, we report first results on correlations observed in alumina-chitosan-gelatin composites, which were chosen as a model system to test and compare the effect of particle size and processing parameters on their mechanical properties at a specific composition. Our study reveals that highly porous (>90%) hybrid materials can be manufactured by freeze casting, through the self-assembly of a polymer and a ceramic phase that occurs during directional solidification, without the need of additional processing steps such as sintering or infiltration. It further illustrates that the properties of freeze-cast hybrid materials can independently be tailored at two levels of their structural hierarchy, allowing for the simultaneous optimization of both mechanical and structural requirements. An increase in freezing rate resulted in decreases in lamellar spacing, cell wall thickness, pore aspect ratio and cross-sectional area, as well as increases in both Young's modulus and compressive yield strength. The mechanical properties of the composite scaffolds increased with an increasing particle size. The results show that both structure and mechanical properties of the freeze-cast composites can be custom-designed and that they are thus ideally suited for a large variety of applications that require high porosity at low or medium load-bearing capacity. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. A Model of Female Sexual Desire: Internalized Working Models of Parent-Child Relationships and Sexual Body Self-Representations.

    Science.gov (United States)

    Cherkasskaya, Eugenia; Rosario, Margaret

    2017-11-01

    The etiology of low female sexual desire, the most prevalent sexual complaint in women, is multi-determined, implicating biological and psychological factors, including women's early parent-child relationships and bodily self-representations. The current study evaluated a model that hypothesized that sexual body self-representations (sexual subjectivity, self-objectification, genital self-image) explain (i.e., mediate) the relation between internalized working models of parent-child relationships (attachment, separation-individuation, parental identification) and sexual desire in heterosexual women. We recruited 614 young, heterosexual women (M = 25.5 years, SD = 4.63) through social media. The women completed an online survey. Structural equation modeling was used. The hypotheses were supported in that the relation between internalized working models of parent-child relationships (attachment and separation-individuation) and sexual desire was mediated by sexual body self-representations (sexual body esteem, self-objectification, genital self-image). However, parental identification was not related significantly to sexual body self-representations or sexual desire in the model. Current findings demonstrated that understanding female sexual desire necessitates considering women's internalized working models of early parent-child relationships and their experiences of their bodies in a sexual context. Treatment of low or absent desire in women would benefit from modalities that emphasize early parent-child relationships as well as interventions that foster mind-body integration.

  17. Reappraising the relationships between physics students’ mental models and predictions: An example of heat convection

    Directory of Open Access Journals (Sweden)

    Guo-Li Chiou

    2013-05-01

    Full Text Available Although prediction is claimed to be a prime function of mental models, to what extent students can run their mental models to make predictions of physical phenomena remains uncertain. The purpose of this study, therefore, was first to investigate 30 physics students’ mental models of heat convection, and then to examine the relationship between their mental models and predictions of convection-related phenomena. A series of semistructured interviews was conducted to probe the participants’ mental models and predictions of heat convection, and the constant comparative method was adopted for data analysis. The results reveal that the participants held a variety of mental models of heat convection, and nearly half held flawed mental models rather than a scientifically compatible one. In addition, while many participants attempted to run their mental models to make a prediction at the beginning stage of solving an interview problem, the relationship between the models and predictions became increasingly complex as the problem solving process continued. The relationships between mental models and predictions, however, could be better understood by considering the completeness of a mental model, the scale of analyzing mental models, and the retrieval of different formats of mental representations.

  18. Thermal and structural properties of spray pyrolysed CdS thin film

    Indian Academy of Sciences (India)

    Unknown

    Thermal and structural properties of CdS thin film. 235. 235 by photoacoustic technique. Polycrystalline CdTe films having 55 µm thickness were grown onto the glass slides using the close space vapour technique. The total thick- ness of two-layer system (glass and CdSe thin film) could be changed by varying the thickness ...

  19. Unbounded-rate Markov decision processes : structural properties via a parametrisation approach

    NARCIS (Netherlands)

    Blok, H.

    2016-01-01

    This research is interested in optimal control of Markov decision processes (MDPs). Herein a key role is played by structural properties. Properties such as monotonicity and convexity help in finding the optimal policy. Value iteration is a tool to derive such properties in discrete time processes.

  20. Understanding Structure-Property Relations of Compressed Glasses through Relaxation Studies

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Svenson, Mouritz Nolsøe; Youngman, Randall E.

    When a glassy material or its liquid state is subjected to sufficiently high pressure, significant changes can take place in the short- and medium-range structure, vibrational density of states, and physical properties. It is crucial to determine and understand the structure-property relations un...

  1. Relationships among Adolescents' Leisure Motivation, Leisure Involvement, and Leisure Satisfaction: A Structural Equation Model

    Science.gov (United States)

    Chen, Ying-Chieh; Li, Ren-Hau; Chen, Sheng-Hwang

    2013-01-01

    The purpose of this cross-sectional study was to test a cause-and-effect model of factors affecting leisure satisfaction among Taiwanese adolescents. A structural equation model was proposed in which the relationships among leisure motivation, leisure involvement, and leisure satisfaction were explored. The study collected data from 701 adolescent…

  2. Cotrainers as Models of Relationships: Effects of the Outcome of Couples Therapy.

    Science.gov (United States)

    Epstein, Norman; And Others

    1979-01-01

    Investigated the generally neglected effects of the cotrainer relationship in studies of the outcome of couples communication training. Male-female cotrainer pairs modeled verbal dominance patterns similar or dissimilar to those of client couples. Changes in couples' speaking patterns after a two-hour workshop mirrored their trainers' models.…

  3. Exploring Third-Grade Student Model-Based Explanations about Plant Relationships within an Ecosystem

    Science.gov (United States)

    Zangori, Laura; Forbes, Cory T.

    2015-01-01

    Elementary students should have opportunities to develop scientific models to reason and build understanding about how and why plants depend on relationships within an ecosystem for growth and survival. However, scientific modeling practices are rarely included within elementary science learning environments and disciplinary content is often…

  4. The Learning-Teaching Nexus: Modelling the Learning-Teaching Relationship in Higher Education

    Science.gov (United States)

    Knewstubb, Bernadette

    2016-01-01

    The teaching-learning relationship is often described as a conversation. However, many models of teaching and learning depict the worlds of teacher and learner as enclosed and inaccessible, linked by apparently transferred communicative meanings. A new interdisciplinary learning-teaching nexus (LTN) model combines perspectives from higher…

  5. The Development of Spelling-Sound Relationships in a Model of Phonological Reading.

    Science.gov (United States)

    Zorzi, Marco; Houghton, George; Butterworth, Brian

    1998-01-01

    Developmental aspects of spelling-to-sound mapping for English monosyllabic words are investigated with a simple two-layer network model using a simple, general learning rule. The model is trained on both regularly and irregularly spelled words but extracts regular spelling to sound relationships, which it can apply to new words. Training-related…

  6. Generalized linear mixed models can detect unimodal species-environment relationships

    NARCIS (Netherlands)

    Jamil, Tahira; Braak, ter C.J.F.

    2013-01-01

    Niche theory predicts that species occurrence and abundance show non-linear, unimodal relationships with respect to environmental gradients. Unimodal models, such as the Gaussian (logistic) model, are however more difficult to fit to data than linear ones, particularly in a multi-species context in

  7. The Sport Commitment Model: An Investigation of Structural Relationships with Thai Youth Athlete Populations

    Science.gov (United States)

    Choosakul, Chairat; Vongjaturapat, Naruepon; Li, Fuzhong; Harmer, Peter

    2009-01-01

    Grounded in the conceptual framework of the Sport Commitment Model and previous empirical studies conducted in Western countries, this study was designed to (a) test and validate a Thai version of the Athlete Opinion Survey to assess components of the Sport Commitment Model in Thai youth athletes and (b) examine structural relationships among…

  8. Statistical Methods for Detecting and Modeling General Patterns and Relationships in Lifetime Data

    Energy Technology Data Exchange (ETDEWEB)

    Kvaloey, Jan Terje

    1999-04-01

    In this thesis, the author tries to develop methods of detecting and modeling general patterns and relationships in lifetime data. Tests with power against nonmonotonic trends and nonmonotonic co variate effects are considered, and nonparametric regression methods which allow estimation of fairly general nonlinear relationships are studied. Practical uses of some of the methods are illustrated although in a medical rather than engineering or technological context.

  9. DESIGNING A MODEL OF CUSTOMER RELATIONSHIP MANAGEMENT FOR A MOBILE PHONE COMPANY

    OpenAIRE

    BRUTU MĂDĂLINA; MIHAI DANIELA MELANIA

    2015-01-01

    Customer relationship management refers to establishing, maintaining, developing and optimizing the relations between an organization and its customers and focuses on understanding and meeting its customers’ wishes and demands, the core items of the business strategy of any performant company. This paper aims at designing and testing a model of customer relationship management applicable within a mobile phone company. Starting from this purpose, the main objectives of the research were: prese...

  10. Dog owner interaction style: the transmission of working models in human/non-human caregiving relationships

    OpenAIRE

    Taggart, Jill Monica

    2011-01-01

    A model of parental sensitivity in caregiving informs later romantic relationships and is transmitted in caregiving behaviours to children. Differences in parental caregiving contribute to individual differences in infant attachment style. The owner/dog bond mirrors this relationship as dog careseeking activates owner caregiving. The aim of this thesis was to investigate the role of individual differences in owner caregiving on dog attachment style.The first study defined dog attachment style...

  11. Using Carl Rogers' person-centered model to explain interpersonal relationships at a school of nursing.

    Science.gov (United States)

    Bryan, Venise D; Lindo, Jascinth; Anderson-Johnson, Pauline; Weaver, Steve

    2015-01-01

    Faculty members are viewed as nurturers within the academic setting and may be able to influence students' behaviors through the formation of positive interpersonal relationships. Faculty members' attributes that best facilitated positive interpersonal relationships according to Carl Rogers' Person-Centered Model was studied. Students (n = 192) enrolled in a 3-year undergraduate nursing program in urban Jamaica were randomly selected to participate in this descriptive cross-sectional study. A 38-item questionnaire on interpersonal relationships with nursing faculty and students' perceptions of their teachers was utilized to collect data. Factor analysis was used to create factors of realness, prizing, and empathetic understanding. Multiple linear regression analysis on the interaction of the 3 factors and interpersonal relationship scores was performed while controlling for nursing students' study year and age. One hundred sixty-five students (mean age: 23.18 ± 4.51years; 99% female) responded. The regression model explained over 46% of the variance. Realness (β = 0.50, P < .001) was the only significant predictor of the interpersonal relationship scores assigned by the nursing students. Of the total number of respondents, 99 students (60%) reported satisfaction with the interpersonal relationships shared with faculty. Nursing students' perception of faculty members' realness appeared to be the most significant attribute in fostering positive interpersonal relationships. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. The model relationship of wastes for parameter design with green lean production of fresh water

    Directory of Open Access Journals (Sweden)

    Mastiadi Tamjidillah

    2017-12-01

    Full Text Available Lean manufacturing is about eliminating waste including the seven traditional, this writing suggested an observation on no value added of seven wastes influencing the process of fresh water production. The relationship value among waste was statistically verified to create an approach for continuous improvement action. Thus, the main goal of this research is to develop a methodology of relationship among wastes and eliminate them. In relationship among wastes, it could be known that the high value indicating how often it happened in the production process gave direct cause in the system of fresh water treatment. A recommendation to reduce the highest value of waste is by doing improvement on parameter setting to obtain an optimum mixing model between water supply, alum and stroke pump with Taguchi method. The interaction of relationship among these seven types of waste can be portrayed using fishbone diagram and a relationship model among wastes using PLS smart (partial least squares. The final relationship model with the highest value of waste was analyzed using off-line quality control to upgrade the quality of fresh water used as the basis to eliminate waste and find out the optimal parameter of mixing process in accordance with the health standard.

  13. The Relationship between Interpersonal Relationship and the Subjective Well-Being of Chinese Primary and Secondary Teachers: A Mediated Moderation Model

    OpenAIRE

    Xuling Zhang; Yong Wang; Xingyun Liu; Shuangxue Xu

    2016-01-01

    Based on positive psychology, this study presented a mediated moderation model in which character strengths moderated the relationship between interpersonal relationship, job satisfaction and subjective well-being, with job satisfaction taking the mediation role among them. A total of 912 teachers participated in four surveys, which include the Oxford Happiness Questionnaire, Values in Action Inventory of Strengths, job satisfaction questionnaire, and the interpersonal relationship questionna...

  14. Structural Properties of Molten CaO-SiO2-P2O5-FeO System

    Science.gov (United States)

    Diao, Jiang; Ke, Zhaoqun; Jiang, Lu; Zhang, Zhen; Zhang, Tao; Xie, Bing

    2017-09-01

    The structural properties of molten CaO-SiO2-P2O5-FeO slag system with varying slag basicity have been investigated by molecular dynamic (MD) simulations using the pairwise potential model. The result shows that more than 95 % Si and 98 % P are four coordinated and form tetrahedral structures. Non-bridging oxygen occupies a predominant position in the system. With basicity increasing from 0.6 to 1.5, the proportion of non-bridging oxygen increases from 66.3 % to 77.3 %, whilst the bridging oxygen decreases from 30.1 % to 10.2 %. Both the result of MD simulations and Raman spectroscopic analysis show the proportion of Q0 increases with increasing slag basicity, whilst Q2 and Q3 decrease. The degree of polymerization of CaO-SiO2-P2O5-FeO system decreases with increasing slag basicity.

  15. SST and OLR relationship during Indian summer monsoon: a coupled climate modelling perspective

    Science.gov (United States)

    Chaudhari, Hemantkumar S.; Hazra, Anupam; Pokhrel, Samir; Chakrabarty, Chandrima; Saha, Subodh Kumar; Sreenivas, P.

    2018-04-01

    The study mainly investigates sea surface temperature (SST) and outgoing longwave radiation (OLR) relationships in coupled climate model. To support the analysis, high-level cloud and OLR relationship is also investigated. High-level cloud and OLR relationship depicts significant negative correlation over the entire monsoon regime. Coupled climate model is able to produce the same. SST and OLR relationship in observation also depicts significant negative relationship, in particular, over the Equatorial Eastern Indian Ocean (EIO) region. Climate Forecast System version 2 (CFSv2) is able to portray the negative relationship over EIO region; however, it is underestimated as compared to observation. Significant negative correlations elucidate that local SSTs regulate the convection and further it initiates Bjerknes feedback in the central Indian Ocean. It connotes that SST anomalies during monsoon period tend to be determined by oceanic forcing. The heat content of the coastal Bay of Bengal shows highest response to EIO SST by a lag of 1 month. It suggests that the coastal region of the Bay of Bengal is marked by coastally trapped Kelvin waves, which might have come from EIO at a time lag of 1 month. Sea surface height anomalies, depth at 20 °C isotherms and depth at 26 isotherms also supports the above hypothesis. Composite analysis based on EIO index and coupled climate model sensitivity experiments also suggest that the coastal Bay of Bengal region is marked by coastally trapped Kelvin waves, which are propagated from EIO at a time lag of 1 month. Thus, SST and OLR relationship pinpoints that the Bay of Bengal OLR (convection) is governed by local ocean-atmospheric coupling, which is influenced by the delayed response from EIO brought forward through oceanic planetary waves at a lag of 1 month. These results have utmost predictive value for seasonal and extended range forecasting. Thus, OLR and SST relationship can constitute a pivotal role in investigating the

  16. The visualization of DHSI based on the relationship model of CL and SA

    Science.gov (United States)

    Wang, Haibo; Guo, Huijuan; Xue, Chengqi

    2013-03-01

    The source and cause of cognitive load (CL) and situation awareness (SA) in digital human-system interface (DHSI) is explained. Based on the analysis of cognitive procedure and the relation of CL and SA, The relationship model of CL and SA in DHSI is put forward. Using the association target and the relationship model of CL and SA, the method and strategy of information visualization of DHSI is presented which is based on the cognitive psychology. Selecting the Boeing 757 autopilot as the case, the comparison of design is shown.

  17. Vp-Vs relationship and amplitude variation with offset modelling of glauconitic greensand

    DEFF Research Database (Denmark)

    Hossain, Zakir; Mukerji, Tapan; Fabricius, Ida Lykke

    2012-01-01

    for reservoir characterization when shearwave data are not available. In published work, the focus is primarily on the Vp-Vs relationship of quartzitic sandstone. In order to broaden the picture we present Vp-Vs relationships of greensand composed of quartz and glauconite by using data from the Paleocene...... modelling works well for greensand shear-wave velocity prediction. We model the seismic response of glauconitic greensand by using laboratory data from the Nini field. Our studies here reveal that brine-saturated glauconitic greensand can have a similar seismic response to that from oil-saturated quartzitic...

  18. Training mode's influences on the relationships between training-load models during basketball conditioning.

    Science.gov (United States)

    Scanlan, Aaron T; Wen, Neal; Tucker, Patrick S; Borges, Nattai R; Dalbo, Vincent J

    2014-09-01

    To compare perceptual and physiological training-load responses during various basketball training modes. Eight semiprofessional male basketball players (age 26.3 ± 6.7 y, height 188.1 ± 6.2 cm, body mass 92.0 ± 13.8 kg) were monitored across a 10-wk period in the preparatory phase of their training plan. Player session ratings of perceived exertion (sRPE) and heart-rate (HR) responses were gathered across base, specific, and tactical/game-play training modes. Pearson correlations were used to determine the relationships between the sRPE model and 2 HR-based models: the training impulse (TRIMP) and summated HR zones (SHRZ). One-way ANOVAs were used to compare training loads between training modes for each model. Stronger relationships between perceptual and physiological models were evident during base (sRPE-TRIMP r = .53, P training load than the TRIMP (15-65 AU) and SHRZ models (27-170 AU) transitioning between training modes. While the training-load models were significantly correlated during each training mode, weaker relationships were observed during specific conditioning. Comparisons suggest that the HR-based models were less effective in detecting periodized increases in training load, particularly during court-based, intermittent, multidirectional drills. The practical benefits and sensitivity of the sRPE model support its use across different basketball training modes.

  19. Object and subject relations in adulthood--towards an integrative model of interpersonal relationships.

    Science.gov (United States)

    Zvelc, Gregor

    2010-12-01

    In the article the author presents a model of interpersonal relationships based on integration of object relations theory and theory of attachment. He proposes three main bipolar dimensions of interpersonal relationships: Independence - Dependence, Connectedness - Alienation and Reciprocity - Self-absorption. The author also proposes that it is important to distinguish between two main types of adult interpersonal relationships: object and subject relations. Object relations describe relationships in which the other person is perceived as an object that serves the satisfaction of the first person's needs. Object relations are a manifestation of the right pole of the three main dimensions of interpersonal relationships (Dependence, Alienation and Self-absorption). Subject relations are a counter-pole to the concept of object relations. They describe relationships with other people who are experienced as subjects with their own wishes, interests and needs. Subject relations are a manifestation of the left pole of the main dimensions (Independence, Connectedness and Reciprocity). In this article the author specifically focuses on definitions of object relations in adulthood through a description of six sub-dimensions of object relations: Symbiotic Merging, Separation Anxiety, Social Isolation, Fear of Engulfment, Egocentrism and Narcissism. Every sub-dimension is described in connection to adaptive and pathological functioning. Further research is needed to test the clinical and scientific validity of the model.

  20. Parental Modeling and Deidentification in Romantic Relationships Among Mexican-origin Youth.

    Science.gov (United States)

    Kuo, Sally I-Chun; Wheeler, Lorey A; Updegraff, Kimberly A; McHale, Susan M; Umaña-Taylor, Adriana J; Perez-Brena, Norma J

    2017-10-01

    This study investigated youth's modeling of and de-identification from parents in romantic relationships, using two phases of data from adolescent siblings, mothers, and fathers in 246 Mexican-origin families. Each parent reported his/her marital satisfaction and conflict, and youth reported on parent-adolescent warmth and conflict at Time 1. Youth's reports of modeling of and de-identification from their mothers and fathers and three romantic relationship outcomes were assessed at Time 2. Findings revealed that higher parental marital satisfaction, lower marital conflict, and higher warmth and lower conflict in parent-adolescent relationships were associated with more modeling and less de-identification from parents. Moreover, higher de-identification was linked to a greater likelihood of youth being involved in a romantic relationship and cohabitation, whereas more modeling was linked to a lower likelihood of cohabitation and older age of first sex. Discussion underscores the importance of assessing parental modeling and de-identification and understanding correlates of these processes.

  1. Gene-disease relationship discovery based on model-driven data integration and database view definition.

    Science.gov (United States)

    Yilmaz, S; Jonveaux, P; Bicep, C; Pierron, L; Smaïl-Tabbone, M; Devignes, M D

    2009-01-15

    Computational methods are widely used to discover gene-disease relationships hidden in vast masses of available genomic and post-genomic data. In most current methods, a similarity measure is calculated between gene annotations and known disease genes or disease descriptions. However, more explicit gene-disease relationships are required for better insights into the molecular bases of diseases, especially for complex multi-gene diseases. Explicit relationships between genes and diseases are formulated as candidate gene definitions that may include intermediary genes, e.g. orthologous or interacting genes. These definitions guide data modelling in our database approach for gene-disease relationship discovery and are expressed as views which ultimately lead to the retrieval of documented sets of candidate genes. A system called ACGR (Approach for Candidate Gene Retrieval) has been implemented and tested with three case studies including a rare orphan gene disease.

  2. Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network.

    Science.gov (United States)

    Kwok, Jeremy Jie Ming; Lee, Dong-Yup

    2015-01-01

    Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business.

  3. Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network.

    Directory of Open Access Journals (Sweden)

    Jeremy Jie Ming Kwok

    Full Text Available Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business.

  4. Coopetitive Supply Chain Relationship Model: Application to the Smartphone Manufacturing Network

    Science.gov (United States)

    Kwok, Jeremy Jie Ming; Lee, Dong-Yup

    2015-01-01

    Previous researches for understanding supply chain relationship have mostly focused on its vertical collaboration between buyers and suppliers. However, there have been some instances of volatile and stable collaborative relationships amongst competitors such as Apple-Samsung product manufacturer-component supplier relationship and airline alliances, respectively, which is recognized as coopetition. Even though there have been several qualitative studies and a number of game theory models on coopetition, it is rare to find any attempts on quantitative characterization of such coopetitive dynamic behavior in supply chain relationship. Hence, in this work, we formulated a MINLP model mathematically representing coopetitive relationships in a cost efficient supply chain network. In particular, the coopetition factor was newly introduced to measure the degree of coopetition among supply chain players and determine the optimal level of coopetition to engage in. The utility and practicality of the model were strongly demonstrated using a case study of a hypothetical smartphone supply chain network under different scenarios, thus proposing their strategically viable optimal interactions. Therefore, this exploratory study can herald a new era of global coopetitive business. PMID:26186227

  5. Structural properties of iron nitride on Cu(100): An ab-initio molecular dynamics study

    KAUST Repository

    Heryadi, Dodi

    2011-01-01

    Due to their potential applications in magnetic storage devices, iron nitrides have been a subject of numerous experimental and theoretical investigations. Thin films of iron nitride have been successfully grown on different substrates. To study the structural properties of a single monolayer film of FeN we have performed an ab-initio molecular dynamics simulation of its formation on a Cu(100) substrate. The iron nitride layer formed in our simulation shows a p4gm(2x2) reconstructed surface, in agreement with experimental results. In addition to its structural properties, we are also able to determine the magnetization of this thin film. Our results show that one monolayer of iron nitride on Cu(100) is ferromagnetic with a magnetic moment of 1.67 μ B. © 2011 Materials Research Society.

  6. Identifying the Critical Links in Road Transportation Networks: Centrality-based approach utilizing structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Chinthavali, Supriya [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    Surface transportation road networks share structural properties similar to other complex networks (e.g., social networks, information networks, biological networks, and so on). This research investigates the structural properties of road networks for any possible correlation with the traffic characteristics such as link flows those determined independently. Additionally, we define a criticality index for the links of the road network that identifies the relative importance in the network. We tested our hypotheses with two sample road networks. Results show that, correlation exists between the link flows and centrality measures of a link of the road (dual graph approach is followed) and the criticality index is found to be effective for one test network to identify the vulnerable nodes.

  7. Physico-mechanical and structural properties of eggshell membrane gelatin- chitosan blend edible films

    DEFF Research Database (Denmark)

    Mohammadi, Reza; Mohammadifar, Mohammad Amin; Rouhi, Milad

    2018-01-01

    This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (p< 0.05), but r......This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (p... interactions introduced by the addition of chitosan to eggshell membrane gelatin as new resources could improve the films’ functional properties....

  8. Chemical and structural properties of Pd nanoparticle-decorated graphene-Electron spectroscopic methods and QUASES

    Czech Academy of Sciences Publication Activity Database

    Lesiak, B.; Jiříček, Petr; Bieloshapka, Igor

    2017-01-01

    Roč. 404, May (2017), s. 300-309 ISSN 0169-4332 R&D Projects: GA MŠk LM2015088 Institutional support: RVO:68378271 Keywords : graphite (Gr) * graphene oxide (GO) * reduced graphene oxide (RGO) * Pd nanoparticles * XPS * QUASES * REELS * chemical and structural properties Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.387, year: 2016

  9. Understanding and Improving High-Temperature Structural Properties of Metal-Silicide Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bruce S. Kang

    2005-10-10

    The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introduction of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo

  10. Constellations of dyadic relationship quality in stepfamilies: A factor mixture model.

    Science.gov (United States)

    Jensen, Todd M

    2017-12-01

    Stepfamilies are an increasingly common family form, marked by distinct challenges, opportunities, and complex networks of dyadic relationships that can transcend single households. There exists a dearth of typological analyses by which constellations of dyadic processes in stepfamilies are holistically analyzed. Factor mixture modeling is used to identify population heterogeneity with respect to features of mother-child, stepfather-child, nonresident father-child, and stepcouple relationships using a representative sample of 1,182 adolescents in mother-stepfather families with living nonresident fathers from Wave I of the National Longitudinal Study of Adolescent to Adult Health. Results favor a 4-class factor-mixture solution with class-specific factor covariance matrices. Class 1 (n = 302, 25.5%), the residence-centered pattern, was marked by high-quality residential relationships. Class 2 (n = 307, 26%), the inclusive pattern, was marked by high-quality relationships across all four dyads, with an especially involved nonresident father-child relationship. Class 3 (n = 350, 29.6%), the unhappy couple pattern, was marked by very low stepcouple relationship quality. Class 4 (n = 223, 18.9%), the parent-child disconnection pattern, was marked by distant relationships between youth and all three parental figures. The residence-centered and inclusive patterns encompassed some positive correlations between dyadic relationships whereas the unhappy couple and parent-child disconnection patterns encompassed some negative correlations between dyadic relationships. The patterns present with differences across sociodemographic and substantive covariates and highlight important opportunities for the development of new and innovative interventions, particularly to meet the needs of stepfamilies that reflect the parent-child disconnection pattern. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  11. The Relationship between Economic Growth and Money Laundering – a Linear Regression Model

    Directory of Open Access Journals (Sweden)

    Daniel Rece

    2009-09-01

    Full Text Available This study provides an overview of the relationship between economic growth and money laundering modeled by a least squares function. The report analyzes statistically data collected from USA, Russia, Romania and other eleven European countries, rendering a linear regression model. The study illustrates that 23.7% of the total variance in the regressand (level of money laundering is “explained” by the linear regression model. In our opinion, this model will provide critical auxiliary judgment and decision support for anti-money laundering service systems.

  12. The Relationship between the Big-Five Model of Personality and Self-Regulated Learning Strategies

    Science.gov (United States)

    Bidjerano, Temi; Dai, David Yun

    2007-01-01

    The study examined the relationship between the big-five model of personality and the use of self-regulated learning strategies. Measures of self-regulated learning strategies and big-five personality traits were administered to a sample of undergraduate students. Results from canonical correlation analysis indicated an overlap between the…

  13. Expanding business-to-business customer relationships : modeling the customer's upgrade decision

    NARCIS (Netherlands)

    Bolton, R.; Lemon, K.N.; Verhoef, P.C.

    This article develops a model of a business customer's decision to upgrade service contracts conditional on the decision to renew the contract. It proposes that the firm's upgrade decision is influenced by (1) decision-maker perceptions of the relationship with the supplier, (2) contract-level

  14. A High-Dimensional, Multivariate Copula Approach to Modeling Multivariate Agricultural Price Relationships and Tail Dependencies

    Science.gov (United States)

    Xuan Chi; Barry Goodwin

    2012-01-01

    Spatial and temporal relationships among agricultural prices have been an important topic of applied research for many years. Such research is used to investigate the performance of markets and to examine linkages up and down the marketing chain. This research has empirically evaluated price linkages by using correlation and regression models and, later, linear and...

  15. Predictive and Explanatory Relationship Model between Procrastination, Motivation, Anxiety and Academic Achievement

    Science.gov (United States)

    Akpur, Ugur

    2017-01-01

    Purpose: The purpose of this study is to determine the predictive and explanatory relationship model between procrastination, motivation, anxiety and academic achievement of university students. Research Methods: In this study, a causal research design was used. The study group consisted of 211 participants. In order to determine their motivation…

  16. Relationships between Visual Static Models and Students' Written Solutions to Fraction Tasks

    Science.gov (United States)

    Anderson-Pence, Katie L.; Moyer-Packenham, Patricia S.; Westenskow, Arla; Shumway, Jessica; Jordan, Kerry

    2014-01-01

    The purpose of this study was to deconstruct the relationship between visual static models and students' written solutions to fraction problems using a large sample of students' solutions. Participants in the study included 162 third-grade and 209 fourth-grade students from 17 different classrooms. Students' written responses to open-ended tasks…

  17. Modeling the Relationship between High School Students' Chemistry Self-Efficacy and Metacognitive Awareness

    Science.gov (United States)

    Kirbulut, Zubeyde Demet

    2014-01-01

    In this study, the relationship between students' chemistry self-efficacy beliefs and metacognitive awareness was investigated utilizing a path model. There were 268 chemistry high school students (59% 10th grade and 41% 11th grade) participated in the study. The students took two-hour chemistry course in the 9th and 10th grade and three-hour…

  18. Exploring Reading Comprehension Skill Relationships through the G-DINA Model

    Science.gov (United States)

    Chen, Huilin; Chen, Jinsong

    2016-01-01

    By analysing the test data of 1029 British secondary school students' performance on 20 Programme for International Student Assessment English reading items through the generalised deterministic input, noisy "and" gate (G-DINA) model, the study conducted two investigations on exploring the relationships among the five reading…

  19. Modeling the Relationship between Pre-Service Teachers' TPACK and Digital Nativity

    Science.gov (United States)

    Kabakci Yurdakul, Isil

    2018-01-01

    The purpose of this study is to build a structural equation model that predicts the relationship between Technological Pedagogical Content Knowledge (TPACK) competencies and digital nativity. The data was collected from 1493 Turkish pre-service teachers. Two instruments were used in the data collection; a TPACK-deep scale and a Turkish adaptation…

  20. The Relationship between Civic Behavior and Civic Values: A Conceptual Model

    Science.gov (United States)

    Bryant, Alyssa N.; Gayles, Joy Gaston; Davis, Heather A.

    2012-01-01

    This study examined the relationships among college students' civic values and behaviors, college culture, and college involvement, accounting for their pre-college inclinations toward civic responsibility. Using a longitudinal, national dataset comprised of 3,680 college students, the study employed structural equation modeling to identify a…

  1. Understanding complex governance relationships in food safety regulation : The RIT model as a theoretical lens

    NARCIS (Netherlands)

    Havinga, Tetty; Verbruggen, Paul

    In this contribution we discuss the added value of the RIT model for the analysis of complex governance relationships in the regulation of food safety. By exploring regimes of food safety involving the European Union and the Global Food Safety Initiative, we highlight the diverse and complex

  2. The reciprocal relationship between compounding awareness and vocabulary knowledge in Chinese: a latent growth model study

    Directory of Open Access Journals (Sweden)

    Yahua eCheng

    2015-04-01

    Full Text Available The aim of this study is to examine the developmental relationship between compounding awareness and vocabulary knowledge from grades 1 to 2 in Chinese children. In this study, 149 Chinese children were tested on compounding awareness and vocabulary knowledge from Time 1 to Time 4, with nonverbal IQ, working memory, phonological awareness, orthographical awareness, and rapid automatized naming at Time 1 as control variables. Latent growth modeling was conducted to analyze the data. Univariate models separately calculated children’s initial levels and growth rates in compounding awareness and vocabulary knowledge. Bivariate model was used to examine the direction of the developmental relationships between the two variables with other cognitive and linguistic variables and the autoregression controlled. The results demonstrated that the initial level of compounding awareness predicted the growth rate of vocabulary knowledge, and the reverse relation was also found, after controlling for other cognitive and linguistic variables and the autoregression. The results suggested a reciprocal developmental relationship between children’s compounding awareness and vocabulary knowledge for Chinese children, a finding that informs current models of the relationship between morphological awareness and vocabulary knowledge.

  3. The reciprocal relationship between compounding awareness and vocabulary knowledge in Chinese: a latent growth model study.

    Science.gov (United States)

    Cheng, Yahua; Li, Liping; Wu, Xinchun

    2015-01-01

    The aim of this study is to examine the developmental relationship between compounding awareness and vocabulary knowledge from grades 1 to 2 in Chinese children. In this study, 149 Chinese children were tested on compounding awareness and vocabulary knowledge from Time 1 to Time 4, with non-verbal IQ, working memory, phonological awareness, orthographical awareness, and rapid automatized naming at Time 1 as control variables. Latent growth modeling was conducted to analyze the data. Univariate models separately calculated children's initial levels and growth rates in compounding awareness and vocabulary knowledge. Bivariate model was used to examine the direction of the developmental relationships between the two variables with other cognitive and linguistic variables and the autoregression controlled. The results demonstrated that the initial level of compounding awareness predicted the growth rate of vocabulary knowledge, and the reverse relation was also found, after controlling for other cognitive and linguistic variables and the autoregression. The results suggested a reciprocal developmental relationship between children's compounding awareness and vocabulary knowledge for Chinese children, a finding that informs current models of the relationship between morphological awareness and vocabulary knowledge.

  4. Relationship between Family Adaptability, Cohesion and Adolescent Problem Behaviors: Curvilinearity of Circumplex Model

    OpenAIRE

    Joh, Ju Youn; Kim, Sun; Park, Jun Li; Kim, Yeon Pyo

    2013-01-01

    Background The Family Adaptability and Cohesion Evaluation Scale (FACES) III using the circumplex model has been widely used in investigating family function. However, the criticism of the curvilinear hypothesis of the circumplex model has always been from an empirical point of view. This study examined the relationship between adolescent adaptability, cohesion, and adolescent problem behaviors, and especially testing the consistency of the curvilinear hypotheses with FACES III. Methods We us...

  5. Some insights for a relationship marketing model integrating SERVQUAL and customer loyalty in dental clinics

    OpenAIRE

    Vargas Perez, Ana Maria; Grijalvo Martin, Maria Mercedes; Mercado Idoeta, Carmelo

    2012-01-01

    The demand of new services, the emergence of new business models, insufficient innovation, underestimation of customer loyalty and reluctance to adopt new management are evidence of the deficiencies and the lack of research about the relations between patients and dental clinics. In this article we propose the structure of a model of Relationship Marketing (RM) in the dental clinic that integrates information from SERVQUAL, Customer Loyalty (CL) and activities of RM and combines the vision of...

  6. QSPR models based on molecular mechanics and quantum chemical calculations. 2. Thermodynamic properties of alkanes, alcohols, polyols, and ethers

    DEFF Research Database (Denmark)

    Dyekjær, Jane Dannow; Jonsdottir, Svava Osk

    2003-01-01

    Quantitative Structure-Property Relationship (QSPR) models for prediction of various thermodynamic properties of simple organic compounds have been developed. A number of new descriptors are proposed and used alongside with descriptors available within the Codessa program. An important feature in...

  7. Complementary models of tree species-soil relationships in old-growth temperate forests

    Science.gov (United States)

    Cross, Alison; Perakis, Steven S.

    2011-01-01

    Ecosystem level studies identify plant soil feed backs as important controls on soil nutrient availability,particularly for nitrogen and phosphorus. Although site and species specific studies of tree species soil relationships are relatively common,comparatively fewer studies consider multiple coexisting speciesin old-growth forests across a range of sites that vary underlying soil fertility. We characterized patterns in forest floor and mineral soil nutrients associated with four common tree species across eight undisturbed old-growth forests in Oregon, USA, and used two complementary conceptual models to assess tree species soil relationships. Plant soil feedbacks that could reinforce sitelevel differences in nutrient availability were assessed using the context dependent relationships model, where by relative species based differences in each soil nutrient divergedorconvergedas nutrient status changed across sites. Tree species soil relationships that did not reflect strong feedbacks were evaluated using a site independent relationships model, where by forest floor and surface mineral soil nutrient tools differed consistently by tree species across sites,without variation in deeper mineral soils. We found that theorganically cycled elements carbon, nitrogen, and phosphorus exhibited context-dependent differences among species in both forest floor and mineral soil, and most of ten followed adivergence model,where by species differences were greatest at high-nutrient sites. These patterns are consistent with the oryemphasizing biotic control of these elements through plant soil feedback mechanisms. Site independent species differences were strongest for pool so if the weather able cations calcium, magnesium, potassium,as well as phosphorus, in mineral soils. Site independent species differences in forest floor nutrients we reattributable too nespecies that displayed significant greater forest floor mass accumulation. Our finding confirmed that site-independent and

  8. Infertile Individuals’ Marital Relationship Status, Happiness, and Mental Health: A Causal Model

    Directory of Open Access Journals (Sweden)

    Seyed Habiballah Ahmadi Forooshany

    2014-11-01

    Full Text Available Background: This study examined the causal model of relation between marital relationship status, happiness, and mental health in infertile individuals. Materials and Methods: In this descriptive study, 155 subjects (men: 52 and women: 78, who had been visited in one of the infertility Centers, voluntarily participated in a self-evaluation. Golombok Rust Inventory of Marital Status, Oxford Happiness Questionnaire, and General Health Questionnaire were used as instruments of the study. Data was analyzed by SPSS17 and Amos 5 software using descriptive statistics, independent sample t test, and path analysis. Results: Disregarding the gender factor, marital relationship status was directly related to happiness (p<0.05 and happiness was directly related to mental health, (p<0.05. Also, indirect relation between marital relationship status and mental health was significant (p<0.05. These results were confirmed in women participants but in men participants only the direct relation between happiness and mental health was significant (p<0.05. Conclusion: Based on goodness of model fit in fitness indexes, happiness had a mediator role in relation between marital relationship status and mental health in infertile individuals disregarding the gender factor. Also, considering the gender factor, only in infertile women, marital relationship status can directly and indirectly affect happiness and mental health.

  9. Variance Distribution in Sibling Relationships: Advantages of Multilevel Modeling Using Full Sibling Groups.

    Science.gov (United States)

    Marciniak, Karyn

    2017-03-01

    The majority of research on sibling relationships has investigated only one or two siblings in a family, but there are many theoretical and methodological limitations to this single dyadic perspective. This study uses multiple siblings (541 adults) in 184 families, where 96 of these families had all siblings complete the study, to demonstrate the value in including full sibling groups when conducting research on sibling relationships. Two scales, positivity and willingness to sacrifice, are evaluated with a multilevel model to account for the nested nature of family relationships. The distribution of variance across three levels: relationship, individual, and family are computed, and results indicate that the relationship level explains the most variance in positivity, whereas the individual level explains the majority of variance in willingness to sacrifice. These distributions are affected by gender composition and family size. The results of this study highlight an important and often overlooked element of family research: The meaning of a scale changes based on its distribution of variance at these three levels. Researchers are encouraged to be cognizant of the variance distribution of their scales when studying sibling relationships and to incorporate more full sibling groups into their research methods and study design. © 2015 Family Process Institute.

  10. Network modeling reveals prevalent negative regulatory relationships between signaling sectors in Arabidopsis immune signaling.

    Directory of Open Access Journals (Sweden)

    Masanao Sato

    Full Text Available Biological signaling processes may be mediated by complex networks in which network components and network sectors interact with each other in complex ways. Studies of complex networks benefit from approaches in which the roles of individual components are considered in the context of the network. The plant immune signaling network, which controls inducible responses to pathogen attack, is such a complex network. We studied the Arabidopsis immune signaling network upon challenge with a strain of the bacterial pathogen Pseudomonas syringae expressing the effector protein AvrRpt2 (Pto DC3000 AvrRpt2. This bacterial strain feeds multiple inputs into the signaling network, allowing many parts of the network to be activated at once. mRNA profiles for 571 immune response genes of 22 Arabidopsis immunity mutants and wild type were collected 6 hours after inoculation with Pto DC3000 AvrRpt2. The mRNA profiles were analyzed as detailed descriptions of changes in the network state resulting from the genetic perturbations. Regulatory relationships among the genes corresponding to the mutations were inferred by recursively applying a non-linear dimensionality reduction procedure to the mRNA profile data. The resulting static network model accurately predicted 23 of 25 regulatory relationships reported in the literature, suggesting that predictions of novel regulatory relationships are also accurate. The network model revealed two striking features: (i the components of the network are highly interconnected; and (ii negative regulatory relationships are common between signaling sectors. Complex regulatory relationships, including a novel negative regulatory relationship between the early microbe-associated molecular pattern-triggered signaling sectors and the salicylic acid sector, were further validated. We propose that prevalent negative regulatory relationships among the signaling sectors make the plant immune signaling network a "sector

  11. QSAR DataBank repository: open and linked qualitative and quantitative structure-activity relationship models.

    Science.gov (United States)

    Ruusmann, V; Sild, S; Maran, U

    2015-01-01

    Structure-activity relationship models have been used to gain insight into chemical and physical processes in biomedicine, toxicology, biotechnology, etc. for almost a century. They have been recognized as valuable tools in decision support workflows for qualitative and quantitative predictions. The main obstacle preventing broader adoption of quantitative structure-activity relationships [(Q)SARs] is that published models are still relatively difficult to discover, retrieve and redeploy in a modern computer-oriented environment. This publication describes a digital repository that makes in silico (Q)SAR-type descriptive and predictive models archivable, citable and usable in a novel way for most common research and applied science purposes. The QSAR DataBank (QsarDB) repository aims to make the processes and outcomes of in silico modelling work transparent, reproducible and accessible. Briefly, the models are represented in the QsarDB data format and stored in a content-aware repository (a.k.a. smart repository). Content awareness has two dimensions. First, models are organized into collections and then into collection hierarchies based on their metadata. Second, the repository is not only an environment for browsing and downloading models (the QDB archive) but also offers integrated services, such as model analysis and visualization and prediction making. The QsarDB repository unlocks the potential of descriptive and predictive in silico (Q)SAR-type models by allowing new and different types of collaboration between model developers and model users. The key enabling factor is the representation of (Q)SAR models in the QsarDB data format, which makes it easy to preserve and share all relevant data, information and knowledge. Model developers can become more productive by effectively reusing prior art. Model users can make more confident decisions by relying on supporting information that is larger and more diverse than before. Furthermore, the smart repository

  12. Network of Ethical Relationships model for global North-South population health research.

    Science.gov (United States)

    Morrison, Karen; Tomsons, Sandra; Gomez, Angela; Forde, Martin

    2017-01-12

    Although a substantial body of literature exists that details how to address ethical issues and provide oversight for traditional research study designs, there currently is very little guidance available to researchers on how to deal with the unique and novel challenges that arise when conducting research that goes outside of these well-defined boundaries. One such example is North-South (N-S) team-based global population health (GPH) research. This paper presents a Network of Ethical Relationships (NER) model which can allow GPH researchers better understand and resolve ethical issues that arise in N-S collaborative research efforts. The NER model elucidates some of the core relationships involved in GPH research and sheds light on the complex milieu of moral, institutional, societal and legal processes in which it is embedded. The utility of the NER model is examined by reviewing 14 GPH research teams, looking at two relationships in more detail - Researcher-Ethics Board, and Researcher-Funder relationships. The paper argues that improved dialogue and flexibility in the application of formal ethical rules and procedures can lead to research being conducted in a more ethical manner since it better accounts for the multitude of voices and perspectives influencing researchers' choices and actions.

  13. The Relationship between entrepreneurial orientation, entrepreneurial competencies, entrepreneurial leadership, and firm performance: A proposed model

    Directory of Open Access Journals (Sweden)

    Chijioke Nwachukwu

    2017-06-01

    Full Text Available This study develops a conceptual model and propositions for researchers to explore the direct and indirect relationship between entrepreneurial orientation, entrepreneurial competencies, entrepreneurial leadership and firm performance. Authors searched various databases including ProQuest, EBSCOhost databases, Scopus for peer reviewed Journals, books, and other relevant publications on the subject. A conceptual review provides direction for researchers to empirically examine the direct relationships between entrepreneurial orientation (EO, entrepreneurial competencies (EC, and firm performance and the mediating effect of entrepreneurial leadership (EL in the relationship between EO, EC, and firm performance. We suggest the use of entrepreneurial orientation scale (EOS, The entrecomp framework (2016, Renko et al., 2015 entrepreneurial leadership styles scale (ENTRELEAD, and Santos & Brito (2012 subjective measurement model for firm performance for measurement of the constructs of EO, EC, EL and performance. For researchers and academics, the model provides a basis for further research by testing empirically the validity of the model. Testing of this model could provide a better understanding of the EO, EC constructs that better predicts strategic and financial performance.

  14. Use of cccupancy models to evaluate expert knowledge-based species-habitat relationships

    Science.gov (United States)

    Iglecia, Monica N.; Collazo, Jaime A.; McKerrow, Alexa

    2012-01-01

    Expert knowledge-based species-habitat relationships are used extensively to guide conservation planning, particularly when data are scarce. Purported relationships describe the initial state of knowledge, but are rarely tested. We assessed support in the data for suitability rankings of vegetation types based on expert knowledge for three terrestrial avian species in the South Atlantic Coastal Plain of the United States. Experts used published studies, natural history, survey data, and field experience to rank vegetation types as optimal, suitable, and marginal. We used single-season occupancy models, coupled with land cover and Breeding Bird Survey data, to examine the hypothesis that patterns of occupancy conformed to species-habitat suitability rankings purported by experts. Purported habitat suitability was validated for two of three species. As predicted for the Eastern Wood-Pewee (Contopus virens) and Brown-headed Nuthatch (Sitta pusilla), occupancy was strongly influenced by vegetation types classified as “optimal habitat” by the species suitability rankings for nuthatches and wood-pewees. Contrary to predictions, Red-headed Woodpecker (Melanerpes erythrocephalus) models that included vegetation types as covariates received similar support by the data as models without vegetation types. For all three species, occupancy was also related to sampling latitude. Our results suggest that covariates representing other habitat requirements might be necessary to model occurrence of generalist species like the woodpecker. The modeling approach described herein provides a means to test expert knowledge-based species-habitat relationships, and hence, help guide conservation planning.

  15. Cost model relationships between textile manufacturing processes and design details for transport fuselage elements

    Science.gov (United States)

    Metschan, Stephen L.; Wilden, Kurtis S.; Sharpless, Garrett C.; Andelman, Rich M.

    1993-01-01

    Textile manufacturing processes offer potential cost and weight advantages over traditional composite materials and processes for transport fuselage elements. In the current study, design cost modeling relationships between textile processes and element design details were developed. Such relationships are expected to help future aircraft designers to make timely decisions on the effect of design details and overall configurations on textile fabrication costs. The fundamental advantage of a design cost model is to insure that the element design is cost effective for the intended process. Trade studies on the effects of processing parameters also help to optimize the manufacturing steps for a particular structural element. Two methods of analyzing design detail/process cost relationships developed for the design cost model were pursued in the current study. The first makes use of existing databases and alternative cost modeling methods (e.g. detailed estimating). The second compares design cost model predictions with data collected during the fabrication of seven foot circumferential frames for ATCAS crown test panels. The process used in this case involves 2D dry braiding and resin transfer molding of curved 'J' cross section frame members having design details characteristic of the baseline ATCAS crown design.

  16. Use of Occupancy Models to Evaluate Expert Knowledge-based Species-Habitat Relationships

    Directory of Open Access Journals (Sweden)

    Monica N. Iglecia

    2012-12-01

    Full Text Available Expert knowledge-based species-habitat relationships are used extensively to guide conservation planning, particularly when data are scarce. Purported relationships describe the initial state of knowledge, but are rarely tested. We assessed support in the data for suitability rankings of vegetation types based on expert knowledge for three terrestrial avian species in the South Atlantic Coastal Plain of the United States. Experts used published studies, natural history, survey data, and field experience to rank vegetation types as optimal, suitable, and marginal. We used single-season occupancy models, coupled with land cover and Breeding Bird Survey data, to examine the hypothesis that patterns of occupancy conformed to species-habitat suitability rankings purported by experts. Purported habitat suitability was validated for two of three species. As predicted for the Eastern Wood-Pewee (Contopus virens and Brown-headed Nuthatch (Sitta pusilla, occupancy was strongly influenced by vegetation types classified as "optimal habitat" by the species suitability rankings for nuthatches and wood-pewees. Contrary to predictions, Red-headed Woodpecker (Melanerpes erythrocephalus models that included vegetation types as covariates received similar support by the data as models without vegetation types. For all three species, occupancy was also related to sampling latitude. Our results suggest that covariates representing other habitat requirements might be necessary to model occurrence of generalist species like the woodpecker. The modeling approach described herein provides a means to test expert knowledge-based species-habitat relationships, and hence, help guide conservation planning.

  17. A revival of the autoregressive distributed lag model in estimating energy demand relationships

    Energy Technology Data Exchange (ETDEWEB)

    Bentzen, J.; Engsted, T.

    1999-07-01

    The findings in the recent energy economics literature that energy economic variables are non-stationary, have led to an implicit or explicit dismissal of the standard autoregressive distribution lag (ARDL) model in estimating energy demand relationships. However, Pesaran and Shin (1997) show that the ARDL model remains valid when the underlying variables are non-stationary, provided the variables are co-integrated. In this paper we use the ARDL approach to estimate a demand relationship for Danish residential energy consumption, and the ARDL estimates are compared to the estimates obtained using co-integration techniques and error-correction models (ECM's). It turns out that both quantitatively and qualitatively, the ARDL approach and the co-integration/ECM approach give very similar results. (au)

  18. An explanatory model regarding the relationships between psychological traits and creativity

    Directory of Open Access Journals (Sweden)

    María Luisa Sanz de Acedo Lizarraga

    2014-01-01

    Full Text Available This research tested a theoretical model of the relationships between certain psychological variables and creativity. Specifically, the relationships among intelligence, personality, intrinsic motivation, creative self-efficacy, and ideational creativity were examined. This study was conducted with a sample of 180 college students (136 women and 44 men who were evaluated with regard to the variables above in two sessions outside the regular academic schedule. The results obtained via structural equation analysis supported the model and revealed that the independent variables (intelligence and personality and the intermediate variables (intrinsic motivation and creative self-efficacy that comprise the proposed model influenced creativity. Furthermore, creative self-efficacy was the most significant trait associated with ideational creativity.

  19. The relationship between the fear-avoidance model of pain and personality traits in fibromyalgia patients.

    Science.gov (United States)

    Martínez, María Pilar; Sánchez, Ana Isabel; Miró, Elena; Medina, Ana; Lami, María José

    2011-12-01

    This study examined the relationship between several cognitive-affective factors of the fear-avoidance model of pain, the big five model of personality, and functional impairment in fibromyalgia (FM). Seventy-four FM patients completed the NEO Five-Factor Inventory, the Pain Catastrophizing Scale, the Pain Anxiety Symptoms Scale-20, the Pain Vigilance and Awareness Questionnaire, and the Impairment and Functioning Inventory. Results indicated that the cognitive-affective factors of pain are differentially associated with personality traits. Neuroticism and conscientiousness were significant predictors of pain catastrophizing, and neuroticism, openness, and agreeableness were significant predictors of pain anxiety. Personality traits did not contribute significantly to vigilance to pain. The effect of neuroticism upon pain anxiety was mediated by pain catastrophizing, and neuroticism showed a trend to moderate the relationship between impairment and pain anxiety. Results support the fear-avoidance model of pain. Implications of the findings for the understanding and management of FM are discussed.

  20. Development of knowledge models by linguistic analysis of lexical relationships in technical documents

    International Nuclear Information System (INIS)

    Seguela, Patrick

    2001-01-01

    This research thesis addresses the problem of knowledge acquisition and structuring from technical texts, and the use of this knowledge in the development of models. The author presents the Cameleon method which aims at extracting binary lexical relationships from technical texts by identifying linguistic markers. The relevance of this method is assessed in the case of four different corpuses: a written technical corpus, an oral technical corpus, a corpus of texts of instructions, and a corpus of academic texts. The author reports the development of a model of representation of knowledge of a specific field by using lexical relationships. The method is then applied to develop a model used in document search within a knowledge management system [fr

  1. A revival of the autoregressive distributed lag model in estimating energy demand relationships

    Energy Technology Data Exchange (ETDEWEB)

    Bentzen, Jan; Engsted, Tom [Aarhus School of Business, Aarhus (Denmark)

    2001-01-01

    The findings in the recent energy economics literature that energy economic variables are non-stationary, have led to an implicit or explicit dismissal of the standard autoregressive distributed lag (ARDL) model in estimating energy demand relationships. Recent research, however, shows that the ARDL model remains valid when the underlying variables are non-stationary, provided the variables are cointegrated. In this paper, we use the ARDL approach to estimate a demand relationship for Danish residential energy consumption, and the ARDL estimates are compared to the estimates obtained using cointegration techniques and error-correction models (ECM's). It turns out that both quantitatively and qualitatively, the ARDL approach and the cointegration/ECM approach give very similar results. (Author)

  2. The Colonization of Private Relationships by the Economic Discourse: A Critic to Descriptive Models of Company

    Directory of Open Access Journals (Sweden)

    Sergio Marcos Carvalho de Avila Negri

    2015-12-01

    Full Text Available Through the reconstructive method of approach and by adopting the communicative rationality habermasian as epistemological framework, this paper discusses the process of colonization of private relations by economic discourse in the corporate field. It examines, in particular, descriptive models of business relationships, as the nexus of contracts theory and dispute resolution forms as the "default rule" and the "hypothetical bargain." With a content analysis of these models, it investigates the hypothesis that there are non-problematized normative claims in the descriptions of business relationships and decision-making in the corporate field, such as specialization and efficiency while rationality parameters. It addresses procedural and substantive objections to the approached models.

  3. Nutrient Models Developments Using Runoff-Nutrient Relationships in an Agricultural Prairie Basin, Manitoba.

    Science.gov (United States)

    Mahmood, T. H.; Pomeroy, J. W.; Wheater, H. S.; Elliott, J. A.; Baulch, H. M.; Lindenschmidt, K. E.

    2015-12-01

    Nutrient export to streams and lakes from agricultural activities can result in significant deterioration of water quality and aquatic ecosystem health. In Western Canada, particular concerns arise for prairie agricultural systems, which are dominated by the effects of a cold climate. Insufficient attention has been given to understand the links between cold region watershed responses and nutrient concentration and a robust watershed-scale modeling framework is needed to simulate nutrient concentration and loads. Long-term, field observations of nutrient concentration-runoff relationships were used to develop nutrient concentration models for the Tobacco Creek Model Watershed (TCMW) which drains into the Red River basin. Field observations include streamflow concentrations of N and P at multiple scales from two headwater basins. Distinct nutrient concentration-runoff models for snowmelt, rain on snow (ROS) and rainfall runoff processes were developed from observed runoff-nutrient concentration relationships. Snowmelt runoff had a moderately positive correlation with particulate nutrient concentrations but no correlation with that of dissolved nutrients. ROS runoff had a weak relationship with both particulate and dissolved nutrient concentrations. Rainfall runoff had the strongest positive correlation with particulate nutrient concentrations but no association with that of dissolved nutrients. The modeling approach also identified a clear hysteretic behavior in the relationship between runoff and particulate nutrient concentration during the 2013 snowmelt runoff event at the basin outlet gauge. The models provide insight into the hydrological controls on nutrient export from cold regions watersheds and the strong effects of inter-annual climatic variability. Snowmelt runoff is a reliable exporter of large nutrient loads while nutrient export by rainfall runoff exceeded snowmelt runoff during hydrologically wet summers such as 2002, 2005, 2011 and 2013.

  4. Investigating the Influence Relationship Models for Stocks in Indian Equity Market: A Weighted Network Modelling Study.

    Science.gov (United States)

    Bhattacharjee, Biplab; Shafi, Muhammad; Acharjee, Animesh

    2016-01-01

    The socio-economic systems today possess high levels of both interconnectedness and interdependencies, and such system-level relationships behave very dynamically. In such situations, it is all around perceived that influence is a perplexing power that has an overseeing part in affecting the dynamics and behaviours of involved ones. As a result of the force & direction of influence, the transformative change of one entity has a cogent aftereffect on the other entities in the system. The current study employs directed weighted networks for investigating the influential relationship patterns existent in a typical equity market as an outcome of inter-stock interactions happening at the market level, the sectorial level and the industrial level. The study dataset is derived from 335 constituent stocks of 'Standard & Poor Bombay Stock Exchange 500 index' and study period is 1st June 2005 to 30th June 2015. The study identifies the set of most dynamically influential stocks & their respective temporal pattern at three hierarchical levels: the complete equity market, different sectors, and constituting industry segments of those sectors. A detailed influence relationship analysis is performed for the sectorial level network of the construction sector, and it was found that stocks belonging to the cement industry possessed high influence within this sector. Also, the detailed network analysis of construction sector revealed that it follows scale-free characteristics and power law distribution. In the industry specific influence relationship analysis for cement industry, methods based on threshold filtering and minimum spanning tree were employed to derive a set of sub-graphs having temporally stable high-correlation structure over this ten years period.

  5. Modelling world gold prices and USD foreign exchange relationship using multivariate GARCH model

    Science.gov (United States)

    Ping, Pung Yean; Ahmad, Maizah Hura Binti

    2014-12-01

    World gold price is a popular investment commodity. The series have often been modeled using univariate models. The objective of this paper is to show that there is a co-movement between gold price and USD foreign exchange rate. Using the effect of the USD foreign exchange rate on the gold price, a model that can be used to forecast future gold prices is developed. For this purpose, the current paper proposes a multivariate GARCH (Bivariate GARCH) model. Using daily prices of both series from 01.01.2000 to 05.05.2014, a causal relation between the two series understudied are found and a bivariate GARCH model is produced.

  6. RELATIONSHIP BETWEEN ISO 9001 CERTIFICATION MATURITY AND EFQM BUSINESS EXCELLENCE MODEL RESULTS

    Directory of Open Access Journals (Sweden)

    Luis Miguel Fonseca

    2015-07-01

    Full Text Available Purpose: This exploratory research evaluates if there a relationship between the number of years since an organization has achieved ISO 9001 certification and the highest level of recognition received by the same organization with the EFQM Business Excellence Model.Methodology/Approach: After state of the art review a detailed comparison between both models was made. Fifty two Portuguese organizations were considered and Correlation coefficient Spearman Rho was used to investigate the possible relationships.Findings: Conclusion is that there is indeed a moderate positive correlation between these two variables, the higher the number of years of ISO 9001 certification, the higher the results of the organization EFQM model evaluation and recognition. This supports the assumption that ISO 9001 International Standard by incorporating many of the principles present in the EFQM Business Excellence Model is consistent with this model and can be considered as a step towards that direction.Research Limitation/implication: Due to the dynamic nature of these models that might change over time and the possible time delays between implementation and results, more in-depth studies like experimental design or a longitudinal quasi-experimental design could be used to confirm the results of this investigation.Originality/Value of paper: This research gives additional insights on conjunct studies of both models. The use of external evaluation results carried out by the independent EFQM assessors minimizes the possible bias of previous studies accessing the value of ISO 9001 certification.

  7. Application of boosting classification and regression to modeling the relationships between trace elements and diseases.

    Science.gov (United States)

    Tan, Chao; Chen, Hui; Zhu, Wanping

    2010-05-01

    The study on the relationship between trace elements and diseases often need to build a classification/regression model. Furthermore, the accuracy of such a model is of particular importance and directly decides its applicability. The goal of this study is to explore the feasibility of applying boosting, i.e., a new strategy from machine learning, to model the relationship between trace elements and diseases. Two examples are employed to illustrate the technique in the applications of classification and regression, respectively. The first example involves the diagnosis of anorexia according to the concentrations of six elements (i.e. classification task). Decision stump and support vector machine are used as the weak/base algorithm and reference algorithm, respectively. The second example involves the prediction of breast cancer mortality based on the intake of trace elements (i.e. a regression task). In this regard, partial least squares is not only used as the weak/base algorithm, but also the reference algorithm. The results from both examples confirm the potential of boosting in modeling the relationship between trace elements and diseases.

  8. Make or Buy in a Mature Industry? Models of Clientsupplier Relationships under TCT and RBV Perspectives

    Directory of Open Access Journals (Sweden)

    Manuel Portugal Ferreira

    2010-01-01

    Full Text Available In this paper, we use the transaction cost theory [TCT] and the resource-based view [RBV] to discuss three propositions on the models of client-supplier relationships in mature industries. The two theories seem to advance different organizational forms of the client-supplier relationships, and in some instances are contradictory. How should firms organize to prosper and grow, namely in the international markets? Through the case study of three Portuguese packaging firms, with primary (interviews and secondary data, we discuss how the three firms deploy three distinct strategic organization models in a mature industry. One firm utilizes marketbased governance mechanisms, and concentrates its production in a few selected locations. Another firm vertically integrates almost the entire value chain of the product to provide full service to its clients. The third firm operates in a model of integrated outsourcing, with the installation wall to wall with its clients. The clientsupplier models adopted by these firms are based on efficient, stable, and trustworthy relationships that permit them to focus on their core competences and reduce transaction costs. The superior performance of firms requires a proper alignment of hierarchical and relational governance, taking the dimensions of their transactions into consideration.

  9. Relationship between Remittance and Economic Growth in Bangladesh: an Autoregressive Distributed Lag Model (ARDL

    Directory of Open Access Journals (Sweden)

    Shapan Chandra Majumder

    2016-03-01

    Full Text Available This study examines the long-run impact of remittances on economic growth in Bangladesh. Bangladesh, being one of the top remittance-recipient countries in the world, has drawn attention to the remittance-output relationship in recent years. In 2014, remittances contributed to 8.2% of GDP of Bangladesh while the contribution was 6.7% in 2006. The main objective of this study is to investigate the impact of the remittance on economic growth (GDP. We adopted Autoregressive Distributed Lag (ARDL models or dynamic linear regressions are widely used to examine the relationship between remittances and economic growth in the country. In testing for the unit root properties of the time series data, all variables are found stationary at first differencing level under the ADF and PP stationary tests. The study made use of diagnostic tests such as the residual normality test, heteroskedacity and serial autocorrelation tests for misspecification in order to validate the parameter estimation outcomes achieved by the estimated model. The stability test of the model is also checked by CUSUM test. The ARDL model presents that there exist a statistically significant long run positive relationship between remittance and economic growth of gross domestic product in Bangladesh.

  10. Improvements of ENSO-monsoon relationship in CMIP5 models through statistical downscaling over India.

    Science.gov (United States)

    Akhter, J.; Das, L.; Deb, A.

    2017-12-01

    Present study has assessed the skills of global climate models (GCMS) from coupled model inter-comparison project phase five (CMIP5) in simulating ENSO-monsoon relationships over seven homogeneous zones of India. Observational sea surface temperature (SST) data has revealed that there has been a significant negative correlation between zonal precipitation and Nino 3.4 index over North Mountainous India, North West India, North Central India, West Peninsular India and South Peninsular India. First and third principal component (PC) of zonal precipitation explaining 44.4% and 14.2% variance respectively has also shown significant anti-correlation with Nino 3.4. Analysis with CMIP5 models revealed that majority of GCMs have failed to reproduce both magnitude and phase of such relationships mainly due to poor simulation of Nino 3.4 index. Therefore, an attempt has been made to improve the results through empirical orthogonal function (EOF) based statistical downscaling of CMIP5 GCMs. To downscale Nino 3.4 index, an optimal predictor combination of PCs extracted from EOF fields of large scale GCM predictors like Geo-potential height, u and v wind, Specific and relative humidity and air temperature at pressure levels 500, 850 and 1000 hpa, mean sea level pressure and atmospheric vapor content has been utilized. Results indicated improvements of downscaled CMIP5 models in simulating ENSO-monsoon relationship for zone wise precipitation. Multi-model ensemble (MME) of downscaled GCMs has better skill than individuals GCM. Therefore, downscaled MME may be used more reliably to investigate future ENSO-monsoon relationship under various warming scenarios

  11. Computational modeling in nanomedicine: prediction of multiple antibacterial profiles of nanoparticles using a quantitative structure-activity relationship perturbation model.

    Science.gov (United States)

    Speck-Planche, Alejandro; Kleandrova, Valeria V; Luan, Feng; Cordeiro, Maria Natália D S

    2015-01-01

    We introduce the first quantitative structure-activity relationship (QSAR) perturbation model for probing multiple antibacterial profiles of nanoparticles (NPs) under diverse experimental conditions. The dataset is based on 300 nanoparticles containing dissimilar chemical compositions, sizes, shapes and surface coatings. In general terms, the NPs were tested against different bacteria, by considering several measures of antibacterial activity and diverse assay times. The QSAR perturbation model was created from 69,231 nanoparticle-nanoparticle (NP-NP) pairs, which were randomly generated using a recently reported perturbation theory approach. The model displayed an accuracy rate of approximately 98% for classifying NPs as active or inactive, and a new copper-silver nanoalloy was correctly predicted by this model with consensus accuracy of 77.73%. Our QSAR perturbation model can be used as an efficacious tool for the virtual screening of antibacterial nanomaterials.

  12. Pharmacokinetic/Pharmacodynamic Relationship of Gabapentin in a CFA-induced Inflammatory Hyperalgesia Rat Model

    DEFF Research Database (Denmark)

    Larsen, Malte Selch; Keizer, Ron; Munro, Gordon

    2016-01-01

    PURPOSE: Gabapentin displays non-linear drug disposition, which complicates dosing for optimal therapeutic effect. Thus, the current study was performed to elucidate the pharmacokinetic/pharmacodynamic (PKPD) relationship of gabapentin's effect on mechanical hypersensitivity in a rat model of CFA...... provides further knowledge into the understanding of gabapentin's non-linear pharmacokinetics and the link between plasma/brain disposition and anti-hyperalgesic effects. The model suggests that intestinal absorption is the primary source of non-linearity and that the investigated rat model provides......-induced inflammatory hyperalgesia. METHODS: A semi-mechanistic population-based PKPD model was developed using nonlinear mixed-effects modelling, based on gabapentin plasma and brain extracellular fluid (ECF) time-concentration data and measurements of CFA-evoked mechanical hyperalgesia following administration...

  13. Generalized linear mixed models can detect unimodal species-environment relationships.

    Science.gov (United States)

    Jamil, Tahira; Ter Braak, Cajo J F

    2013-01-01

    Niche theory predicts that species occurrence and abundance show non-linear, unimodal relationships with respect to environmental gradients. Unimodal models, such as the Gaussian (logistic) model, are however more difficult to fit to data than linear ones, particularly in a multi-species context in ordination, with trait modulated response and when species phylogeny and species traits must be taken into account. Adding squared terms to a linear model is a possibility but gives uninterpretable parameters. This paper explains why and when generalized linear mixed models, even without squared terms, can effectively analyse unimodal data and also presents a graphical tool and statistical test to test for unimodal response while fitting just the generalized linear mixed model. The R-code for this is supplied in Supplemental Information 1.

  14. Modeling the relationship between body weight and energy intake: a molecular diffusion-based approach.

    Science.gov (United States)

    Gong, Zhejun; Gong, Zhefeng

    2012-06-29

    Body weight is at least partly controlled by the choices made by a human in response to external stimuli. Changes in body weight are mainly caused by energy intake. By analyzing the mechanisms involved in food intake, we considered that molecular diffusion plays an important role in body weight changes. We propose a model based on Fick's second law of diffusion to simulate the relationship between energy intake and body weight. This model was applied to food intake and body weight data recorded in humans; the model showed a good fit to the experimental data. This model was also effective in predicting future body weight. In conclusion, this model based on molecular diffusion provides a new insight into the body weight mechanisms. This article was reviewed by Dr. Cabral Balreira (nominated by Dr. Peter Olofsson), Prof. Yang Kuang and Dr. Chao Chen.

  15. Carbon Nanotubes Advanced Topics in the Synthesis, Structure, Properties and Applications

    CERN Document Server

    Jorio, Ado; Dresselhaus, Mildred S

    2008-01-01

    The carbon nanotubes field has evolved substantially since the publication of the bestseller "Carbon Nanotubes: Synthesis, Structure, Properties and Applications". The present volume builds on the generic aspects of the aforementioned book, which emphasizes the fundamentals, with the new volume emphasizing areas that have grown rapidly since the first volume, guiding future directions where research is needed and highlighting applications. The volume also includes an emphasis on areas like graphene, other carbon-like and other tube-like materials because these fields are likely to affect and influence developments in nanotubes in the next 5 years.

  16. Study of Structural Properties of Mesoporous Carbon From Fructose with Zinc Borosilicate Activator

    OpenAIRE

    Setianingsih, Tutik; Kartini, Indriana; Arryanto, Yateman

    2014-01-01

    Structural properties, including pore structure, functional group of carbon surface, and crystal structure of carbon built by zinc borosilicate (ZBS) and ZnCl2 (Z) have been investigated in this work. Physically, ZBS and ZnCl2 may act as template of carbon, whereas the Zn(II) cation act as chemical activator of carbonization. All precursors of ZBS (silicagel, boric acid, and ZnCl2) may act as catalysts of caramelization. The caramelization was conducted hydrothermally at 85oC and thermally 1...

  17. Band structure properties of (BGa)P semiconductors for lattice matched integration on (001) silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Nadir; Sweeney, Stephen [Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Hosea, Jeff [Advanced Technology Institute and Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, UK and Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Johor Bahru 81310 (Malaysia); Liebich, Sven; Zimprich, Martin; Volz, Kerstin; Stolz, Wolfgang [Material Sciences Center and Faculty of Physics, Philipps-University, 35032 Marburg (Germany); Kunert, Bernerdette [NAsP III/V GmbH, Am Knechtacker 19, 35041 Marburg (Germany)

    2013-12-04

    We report the band structure properties of (BGa)P layers grown on silicon substrate using metal-organic vapour-phase epitaxy. Using surface photo-voltage spectroscopy we find that both the direct and indirect band gaps of (BGa)P alloys (strained and unstrained) decrease with Boron content. Our experimental results suggest that the band gap of (BGa)P layers up to 6% Boron is large and suitable to be used as cladding and contact layers in GaP-based quantum well heterostructures on silicon substrates.

  18. Study of thermodynamic and structural properties of a flexible homopolymer chain using advanced Monte Carlo methods

    Directory of Open Access Journals (Sweden)

    Hammou Amine Bouziane

    2013-03-01

    Full Text Available We study the thermodynamic and structural properties of a flexible homopolymer chain using both multi canonical Monte Carlo method and Wang-Landau method. In this work, we focus on the coil-globule transition. Starting from a completely random chain, we have obtained a globule for different sizes of the chain. The implementation of these advanced Monte Carlo methods allowed us to obtain a flat histogram in energy space and calculate various thermodynamic quantities such as the density of states, the free energy and the specific heat. Structural quantities such as the radius of gyration where also calculated.

  19. Crystal Structures, Properties and Reactivity of Selected Macrocyclic and Chelate Complexes of Ni(II)

    OpenAIRE

    Churchard, Andrew James

    2012-01-01

    In this dissertation we describe the structure, properties and decomposition reactions of a series of Ni(II) coordination complexes formed from reaction of the appropriate macrocyclic or chelating ligand with a simple nickel salt. The ligands used were 12aneS4 (1,4,7,10-tetrathiacyclododecane), 14aneS4 (1,4,8,11-tetrathiacyclotetradecane), cyclam (1,4,8,11-tetraazacyclotetradecane), dppe (1,2- (diphenylphosphino)ethane), and PP3 (tris-(2-(diphenylphosphino)ethyl)phosphine). The wo...

  20. Using nonlinearity and spatiotemporal property modulation to control effective structural properties: dynamic rods

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Blekhman, Iliya I.

    2007-01-01

    What are the effective properties of a generally nonlinear material or structure, whose local properties are modulated in both space and time? It has been suggested to use spatiotemporal modulation of structural properties to create materials and structures with adjustable effective properties......, and exemplified. Then simple approximate analytical expressions are derived for the effective wave speed and natural frequencies for one-dimensional wave propagation in a nonlinear elastic rod, where the spatiotemporal modulation is imposed as a high-frequency standing wave, supposed to be given. Finally the more...

  1. Evaluating a flash size and energy dissipation relationship through various modeling techniques

    Science.gov (United States)

    Salinas, V.; Brothers, M.; Bruning, E. C.; Mansell, E.

    2017-12-01

    Many studies have investigated the influence of the electrostatic and kinematic environments of thunderstorms on lightning flash size. Recent work has demonstrated a coupling of turbulent kinematic properties to flash size distribution in different regions of a storm. Additional work has also theorized a relationship of flash size and energy to the TKE spectrum. However, the physical basis for using flash size alone in these estimates remains absent. This study used the National Severe Storms Laboratory's Collaborative Model for Multiscale Atmospheric Simulation model (N-COMMAS) to simulate an observed multicellular thunderstorm to investigate the relationship between flash size and energy. Model output included the total energy dissipated for each flash, and the charge, electric potential, electric field where it propagated. These flashes were then modeled in two simplified ways. First, each flash was assumed to be convex hull volumes of charge. A 3D Poisson solver was then used on each charge volume for charge density retrieval and computation of the electric potential, using a theoretical electric field breakeven threshold and charge conservation. Second, a capacitor model was used to estimate the energy dissipated using flash area, charge, and plate spacing obtained from the COMMAS model. These two calculations of flash energy were compared to the COMMAS energy. The results suggested that flash size alone was insufficient in characterizing the energetic properties.

  2. Modelling of long term kinetic evolution: a fruitful relationship between experiment and theoretical development

    International Nuclear Information System (INIS)

    Barbu, A.

    2008-01-01

    Recent developments in multi-scale modelling, based on atomic scale calculations, are leading to a growing conviction that modelling will soon be used to design material components for nuclear reactors. In this article we discuss this assumption on the basis of the relationship between experimental studies and theoretical calculations of the microstructural evolution of materials under irradiation. In the first part of the paper, the available numerical models for long term microstructural evolutions are briefly reviewed. The experimental methods are presented in a second part. In the third part, several examples of fruitful relationships between modelling and experiments are discussed. The first example deals with the isochronal electrical resistivity recovery of electron irradiated ultra pure iron at 14 K, the second one is dedicated to the microstructural evolution of ferritic model alloy during continuous irradiation with 1 MeV electrons at large fluences, the third one is the modelling of He desorption of helium implanted iron, and the fourth example concerns the mechanisms of formation of solute rich clusters observed by 3-dimensional atom probe in irradiated pressure vessel steels of water pressurized nuclear reactors

  3. Relationship between Temperament, Depression, Anxiety, and Hopelessness in Adolescents: A Structural Equation Model

    Directory of Open Access Journals (Sweden)

    Paolo Iliceto

    2011-01-01

    Full Text Available The purpose of this study was to test the validity of affective temperaments for predicting psychiatric morbidity and suicide risk, using a two-factor model to explain the relationships between temperament, anxiety, depression, and hopelessness. We investigated 210 high school students, 103 males and 107 females, 18-19 years old, who were administered self-report questionnaires to assess temperament (TEMPS-A, depression (BDI-II, anxiety (STAI and hopelessness (BHS. The final structural model had a good fit with the data, with two factors significantly correlated, the first labeled unstable cyclothymic temperament including Dysthymic/Cyclothymic/Anxious temperament, Irritable temperament and Depression, and the second labeled Demoralization including Anxiety (State/Trait and Hopelessness. Depression, anxiety and hopelessness are in a complex relationship partly mediated by temperament.

  4. Exploring the inequality-mortality relationship in the US with Bayesian spatial modeling

    Science.gov (United States)

    Yang, Tse-Chuan; Jensen, Leif

    2014-01-01

    While there is evidence to suggest that socioeconomic inequality within places is associated with mortality rates among people living within them, the empirical connection between the two remains unsettled as potential confounders associated with racial and social structure are overlooked. This study seeks to test this relationship, to determine whether it is due to differential levels of deprivation and social capital, and does so with intrinsically conditional autoregressive Bayesian spatial modeling that effectively addresses the bias introduced by spatial dependence. We find that deprivation and social capital partly but not completely account for why inequality is positively associated with mortality and that spatial modeling generates more accurate predictions than does the traditional approach. We advance the literature by unveiling the intervening roles of social capital and deprivation in the inequality-mortality relationship and offering new evidence that inequality matters in US county mortality rates. PMID:26166920

  5. A comprehensive model of stress - The roles of experienced stress and neuroticism in explaining the stress-distress relationship

    NARCIS (Netherlands)

    De Jong, GM; van Sonderen, E; Emmelkamp, PMG

    1999-01-01

    Background: In this study, a complex theoretical model regarding the stress-distress relationship was evaluated. The various components in the model included experienced stress (daily hassles), psychological distress, neuroticism, problem-focused coping, avoidant coping, satisfaction with received

  6. The relationship between carbon dioxide and agriculture in Ghana: a comparison of VECM and ARDL model.

    Science.gov (United States)

    Asumadu-Sarkodie, Samuel; Owusu, Phebe Asantewaa

    2016-06-01

    In this paper, the relationship between carbon dioxide and agriculture in Ghana was investigated by comparing a Vector Error Correction Model (VECM) and Autoregressive Distributed Lag (ARDL) Model. Ten study variables spanning from 1961 to 2012 were employed from the Food Agricultural Organization. Results from the study show that carbon dioxide emissions affect the percentage annual change of agricultural area, coarse grain production, cocoa bean production, fruit production, vegetable production, and the total livestock per hectare of the agricultural area. The vector error correction model and the autoregressive distributed lag model show evidence of a causal relationship between carbon dioxide emissions and agriculture; however, the relationship decreases periodically which may die over-time. All the endogenous variables except total primary vegetable production lead to carbon dioxide emissions, which may be due to poor agricultural practices to meet the growing food demand in Ghana. The autoregressive distributed lag bounds test shows evidence of a long-run equilibrium relationship between the percentage annual change of agricultural area, cocoa bean production, total livestock per hectare of agricultural area, total pulses production, total primary vegetable production, and carbon dioxide emissions. It is important to end hunger and ensure people have access to safe and nutritious food, especially the poor, orphans, pregnant women, and children under-5 years in order to reduce maternal and infant mortalities. Nevertheless, it is also important that the Government of Ghana institutes agricultural policies that focus on promoting a sustainable agriculture using environmental friendly agricultural practices. The study recommends an integration of climate change measures into Ghana's national strategies, policies and planning in order to strengthen the country's effort to achieving a sustainable environment.

  7. The relationship of family characteristics and bipolar disorder using causal-pie models.

    Science.gov (United States)

    Chen, Y-C; Kao, C-F; Lu, M-K; Yang, Y-K; Liao, S-C; Jang, F-L; Chen, W J; Lu, R-B; Kuo, P-H

    2014-01-01

    Many family characteristics were reported to increase the risk of bipolar disorder (BPD). The development of BPD may be mediated through different pathways, involving diverse risk factor profiles. We evaluated the associations of family characteristics to build influential causal-pie models to estimate their contributions on the risk of developing BPD at the population level. We recruited 329 clinically diagnosed BPD patients and 202 healthy controls to collect information in parental psychopathology, parent-child relationship, and conflict within family. Other than logistic regression models, we applied causal-pie models to identify pathways involved with different family factors for BPD. The risk of BPD was significantly increased with parental depression, neurosis, anxiety, paternal substance use problems, and poor relationship with parents. Having a depressed mother further predicted early onset of BPD. Additionally, a greater risk for BPD was observed with higher numbers of paternal/maternal psychopathologies. Three significant risk profiles were identified for BPD, including paternal substance use problems (73.0%), maternal depression (17.6%), and through poor relationship with parents and conflict within the family (6.3%). Our findings demonstrate that different aspects of family characteristics elicit negative impacts on bipolar illness, which can be utilized to target specific factors to design and employ efficient intervention programs. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  8. Structuring properties of irrigation systems : Understanding relations between humans and hydraulics through modeling

    NARCIS (Netherlands)

    Ertsen, M.W.

    2010-01-01

    Irrigation systems were clearly important in ancient times in supplying crops with water. This requires physical distribution facilities and socio-political arrangements to coordinate between actors. Resulting systems are highly diverse, and are being studied extensively within archeology and

  9. Effects of gamma radiation on microbial, physicochemical, and structural properties of whey protein model system.

    Science.gov (United States)

    Wang, X B; Wang, C N; Zhang, Y C; Liu, T T; Lv, J P; Shen, X; Guo, M R

    2018-03-21

    Gamma radiation has been used in food processing for many years, though it has certain effects on food components. Whey protein solutions (10%/30%, wt/vol) were treated with gamma radiation at various dosages (10-25 kGy) and evaluated for microbial changes in the solutions and physicochemical and structural changes of whey proteins. Whey protein solutions after gamma radiation showed substantially lower populations of all viable microorganisms than those of controls. The 10% whey protein solution treated at radiation of 20 or 25 kGy remained sterile for up to 4 wk at room temperature. Gamma radiation increased viscosity and turbidity and decreased soluble nitrogen of whey protein solutions compared to nonradiated control samples regardless of radiation dosage. Nonreducing sodium dodecyl sulfate-PAGE suggested that whey proteins under gamma radiation treatment formed aggregates with high molecular weights. Reducing sodium dodecyl sulfate-PAGE showed that disulfide bonds played a role in gamma radiation-induced whey protein cross-linking. Scanning and transmission electron microscopy micrographs exhibited large aggregates of whey proteins after gamma radiation treatment. Results suggested that gamma radiation could be applied to whey protein solution for purposes of reducing microbial counts and cross-linking protein molecules. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  10. PREFACE: 10th Summer School on Theoretical Physics 'Symmetry and Structural Properties of Condensed Matter'

    Science.gov (United States)

    Lulek, Tadeusz; Wal, Andrzej; Lulek, Barbara

    2010-03-01

    This volume contains the Proceedings of the Tenth Summer School on Theoretical Physics under the banner title 'Symmetry and Structural Properties of Condensed Matter' (SSPCM 2009). The School was organized by Rzeszow University of Technology, Poland, in cooperation with AGH University of Science and Technology, Cracow, Poland, and took place on 2-9 September 2009 in Myczkowce, Poland. With this meeting we have reached the round number ten of the series of biannual SSPCM schools, which started in 1990 and were focused on some advanced mathematical methods of condensed matter physics. The first five meetings were held in Zajaczkowo near Poznan, under the auspices of The Institute of Physics of Adam Mickiewicz University, and the last five in Myczkowce near Rzeszów, in the south-eastern part of Poland. Within these two decades several young workers who started at kindergarten lectures at SSPCM, have now reached their PhD degrees, professorships and authority. Proceedings of the first seven SSPCM meetings were published as separate volumes by World Scientific, and the last two as volumes 30 and 104 of Journal of Physics: Conference Series. The present meeting is also the third of the last schools which put the emphasis on quantum informatics. The main topics of our jubilee SSPCM'09 are the following: Information processing, entanglement, and tensor calculus, Integrable models and unitary symmetry, Finite systems and nanophysics. The Proceedings are divided into three parts accordingly. The school gathered together 55 participants from seven countries and several scientific centers in Poland, accommodating again advanced research with young collaborators and students. Acknowledgements The Organizing Committee would like to express its gratitude to all participants for their many activities during the School and for creating a friendly and inspiring atmosphere within our SSPCM society. Special thanks are due to all lecturers for preparing and presenting their talks and

  11. Phosphorus Export Model Development in a Terminal Lake Basin using Concentration-Streamflow Relationship

    Science.gov (United States)

    Jeannotte, T.; Mahmood, T. H.; Matheney, R.; Hou, X.

    2017-12-01

    Nutrient export to streams and lakes by anthropogenic activities can lead to eutrophication and degradation of surface water quality. In Devils Lake, ND, the only terminal lake in the Northern Great Plains, the algae boom is of great concern due to the recent increase in streamflow and consequent rise in phosphorus (P) export from prairie agricultural fields. However, to date, very few studies explored the concentration (c) -streamflow (q) relationship in the headwater catchments of the Devils Lake basin. A robust watershed-scale quantitative framework would aid understanding of the c-q relationship, simulating P concentration and load. In this study, we utilize c-q relationships to develop a simple model to estimate phosphorus concentration and export from two headwater catchments of different size (Mauvais Coulee: 1032 km2 and Trib 3: 160 km2) draining to Devils Lake. Our goal is to link the phosphorus export model with a physically based hydrologic model to identify major drivers of phosphorus export. USGS provided the streamflow measurements, and we collected water samples (filtered and unfiltered) three times daily during the spring snowmelt season (March 31, 2017- April 12, 2017) at the outlets of both headwater catchments. Our results indicate that most P is dissolved and very little is particulate, suggesting little export of fine-grained sediment from agricultural fields. Our preliminary analyses in the Mauvais Coulee catchment show a chemostatic c-q relationship in the rising limb of the hydrograph, while the recession limb shows a linear and positive c-q relationship. The poor correlation in the rising limb of the hydrograph suggests intense flushing of P by spring snowmelt runoff. Flushing then continues in the recession limb of the hydrograph, but at a more constant rate. The estimated total P load for the Mauvais Coulee basin is 193 kg/km2, consistent with other catchments of similar size across the Red River of the North basin to the east. We expect

  12. Curating and Preparing High-Throughput Screening Data for Quantitative Structure-Activity Relationship Modeling.

    Science.gov (United States)

    Kim, Marlene T; Wang, Wenyi; Sedykh, Alexander; Zhu, Hao

    2016-01-01

    Publicly available bioassay data often contains errors. Curating massive bioassay data, especially high-throughput screening (HTS) data, for Quantitative Structure-Activity Relationship (QSAR) modeling requires the assistance of automated data curation tools. Using automated data curation tools are beneficial to users, especially ones without prior computer skills, because many platforms have been developed and optimized based on standardized requirements. As a result, the users do not need to extensively configure the curation tool prior to the application procedure. In this chapter, a freely available automatic tool to curate and prepare HTS data for QSAR modeling purposes will be described.

  13. Segmented relationships to model erosion of regression effect in Cox regression.

    Science.gov (United States)

    Muggeo, Vito M R; Attanasio, Massimo

    2011-08-01

    In this article we propose a parsimonious parameterisation to model the so-called erosion of the covariate effect in the Cox model, namely a covariate effect approaching to zero as the follow-up time increases. The proposed parameterisation is based on the segmented relationship where proper constraints are set to accomodate for the erosion. Relevant hypothesis testing is discussed. The approach is illustrated on two historical datasets in the survival analysis literature, and some simulation studies are presented to show how the proposed framework leads to a test for a global effect with good power as compared with alternative procedures. Finally, possible generalisations are also presented for future research.

  14. Modelling concentration-analgesia relationships for morphine to evaluate experimental pain models

    DEFF Research Database (Denmark)

    Sverrisdóttir, Eva; Foster, David John Richard; Upton, Richard Neil

    2015-01-01

    The aim of this study was to develop population pharmacokinetic-pharmacodynamic models for morphine in experimental pain induced by skin heat and muscle pressure, and to evaluate the experimental pain models with regard to assessment of morphine pharmacodynamics. In a randomized, double......-blind, placebo-controlled, crossover study, 39 healthy volunteers received an oral dose of 30 mg morphine hydrochloride or placebo. Non-linear mixed effects modelling was used to describe the plasma concentrations of morphine and metabolites, and the analgesic effect of morphine on experimental pain in skin...... and muscle. Baseline pain metrics varied between individuals and occasions, and were described with interindividual and interoccasion variability. Placebo-response did not change with time. For both pain metrics, morphine effect was proportional to baseline pain and was described with a linear model...

  15. Information System Success Model for Customer Relationship Management System in Health Promotion Centers

    Science.gov (United States)

    Choi, Wona; Rho, Mi Jung; Park, Jiyun; Kim, Kwang-Jum; Kwon, Young Dae

    2013-01-01

    Objectives Intensified competitiveness in the healthcare industry has increased the number of healthcare centers and propelled the introduction of customer relationship management (CRM) systems to meet diverse customer demands. This study aimed to develop the information system success model of the CRM system by investigating previously proposed indicators within the model. Methods The evaluation areas of the CRM system includes three areas: the system characteristics area (system quality, information quality, and service quality), the user area (perceived usefulness and user satisfaction), and the performance area (personal performance and organizational performance). Detailed evaluation criteria of the three areas were developed, and its validity was verified by a survey administered to CRM system users in 13 nationwide health promotion centers. The survey data were analyzed by the structural equation modeling method, and the results confirmed that the model is feasible. Results Information quality and service quality showed a statistically significant relationship with perceived usefulness and user satisfaction. Consequently, the perceived usefulness and user satisfaction had significant influence on individual performance as well as an indirect influence on organizational performance. Conclusions This study extends the research area on information success from general information systems to CRM systems in health promotion centers applying a previous information success model. This lays a foundation for evaluating health promotion center systems and provides a useful guide for successful implementation of hospital CRM systems. PMID:23882416

  16. Estimation in a multiplicative mixed model involving a genetic relationship matrix

    Directory of Open Access Journals (Sweden)

    Eccleston John A

    2009-04-01

    Full Text Available Abstract Genetic models partitioning additive and non-additive genetic effects for populations tested in replicated multi-environment trials (METs in a plant breeding program have recently been presented in the literature. For these data, the variance model involves the direct product of a large numerator relationship matrix A, and a complex structure for the genotype by environment interaction effects, generally of a factor analytic (FA form. With MET data, we expect a high correlation in genotype rankings between environments, leading to non-positive definite covariance matrices. Estimation methods for reduced rank models have been derived for the FA formulation with independent genotypes, and we employ these estimation methods for the more complex case involving the numerator relationship matrix. We examine the performance of differing genetic models for MET data with an embedded pedigree structure, and consider the magnitude of the non-additive variance. The capacity of existing software packages to fit these complex models is largely due to the use of the sparse matrix methodology and the average information algorithm. Here, we present an extension to the standard formulation necessary for estimation with a factor analytic structure across multiple environments.

  17. Advances in applied homeostatic modelling of the relationship between thyrotropin and free thyroxine.

    Directory of Open Access Journals (Sweden)

    Rudolf Hoermann

    Full Text Available The relationship between pituitary TSH and thyroid hormones is central to our understanding of thyroid physiology and thyroid function testing. Here, we generated distribution patterns by using validated tools of thyroid modelling.We simulated patterns of individual set points under various conditions, based on a homeostatic model of thyroid feedback control. These were compared with observed data points derived from clinical trials.A random mix of individual set points was reconstructed by simulative modelling with defined structural parameters. The pattern displayed by the cluster of hypothetical points resembled that observed in a natural control group. Moderate variation of the TSH-FT4 gradient over the functional range introduced further flexibility, implementing a scenario of adaptive set points. Such a scenario may be a realistic possibility for instance in treatment where relationships and equilibria between thyroid parameters are altered by various influences such as LT4 dose and conversion efficiency.We validated a physiologically based homeostatic model that permits simulative reconstruction of individual set points. This produced a pattern resembling the observed data under various conditions. Applied modelling, although still experimental at this stage, shows a potential to aid our physiological understanding of the interplay between TSH and thyroid hormones. It should eventually benefit personalised clinical decision making.

  18. Information system success model for customer relationship management system in health promotion centers.

    Science.gov (United States)

    Choi, Wona; Rho, Mi Jung; Park, Jiyun; Kim, Kwang-Jum; Kwon, Young Dae; Choi, In Young

    2013-06-01

    Intensified competitiveness in the healthcare industry has increased the number of healthcare centers and propelled the introduction of customer relationship management (CRM) systems to meet diverse customer demands. This study aimed to develop the information system success model of the CRM system by investigating previously proposed indicators within the model. THE EVALUATION AREAS OF THE CRM SYSTEM INCLUDES THREE AREAS: the system characteristics area (system quality, information quality, and service quality), the user area (perceived usefulness and user satisfaction), and the performance area (personal performance and organizational performance). Detailed evaluation criteria of the three areas were developed, and its validity was verified by a survey administered to CRM system users in 13 nationwide health promotion centers. The survey data were analyzed by the structural equation modeling method, and the results confirmed that the model is feasible. Information quality and service quality showed a statistically significant relationship with perceived usefulness and user satisfaction. Consequently, the perceived usefulness and user satisfaction had significant influence on individual performance as well as an indirect influence on organizational performance. This study extends the research area on information success from general information systems to CRM systems in health promotion centers applying a previous information success model. This lays a foundation for evaluating health promotion center systems and provides a useful guide for successful implementation of hospital CRM systems.

  19. Physical models have gender‐specific effects on student understanding of protein structure–function relationships

    Science.gov (United States)

    Harris, Michelle A.; Chang, Wesley S.; Dent, Erik W.; Nordheim, Erik V.; Franzen, Margaret A.

    2016-01-01

    Abstract Understanding how basic structural units influence function is identified as a foundational/core concept for undergraduate biological and biochemical literacy. It is essential for students to understand this concept at all size scales, but it is often more difficult for students to understand structure–function relationships at the molecular level, which they cannot as effectively visualize. Students need to develop accurate, 3‐dimensional mental models of biomolecules to understand how biomolecular structure affects cellular functions at the molecular level, yet most traditional curricular tools such as textbooks include only 2‐dimensional representations. We used a controlled, backward design approach to investigate how hand‐held physical molecular model use affected students' ability to logically predict structure–function relationships. Brief (one class period) physical model use increased quiz score for females, whereas there was no significant increase in score for males using physical models. Females also self‐reported higher learning gains in their understanding of context‐specific protein function. Gender differences in spatial visualization may explain the gender‐specific benefits of physical model use observed. © 2016 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 44(4):326–335, 2016. PMID:26923186

  20. Physical models have gender-specific effects on student understanding of protein structure-function relationships.

    Science.gov (United States)

    Forbes-Lorman, Robin M; Harris, Michelle A; Chang, Wesley S; Dent, Erik W; Nordheim, Erik V; Franzen, Margaret A

    2016-07-08

    Understanding how basic structural units influence function is identified as a foundational/core concept for undergraduate biological and biochemical literacy. It is essential for students to understand this concept at all size scales, but it is often more difficult for students to understand structure-function relationships at the molecular level, which they cannot as effectively visualize. Students need to develop accurate, 3-dimensional mental models of biomolecules to understand how biomolecular structure affects cellular functions at the molecular level, yet most traditional curricular tools such as textbooks include only 2-dimensional representations. We used a controlled, backward design approach to investigate how hand-held physical molecular model use affected students' ability to logically predict structure-function relationships. Brief (one class period) physical model use increased quiz score for females, whereas there was no significant increase in score for males using physical models. Females also self-reported higher learning gains in their understanding of context-specific protein function. Gender differences in spatial visualization may explain the gender-specific benefits of physical model use observed. © 2016 The Authors Biochemistry and Molecular Biology Education published by Wiley Periodicals, Inc. on behalf of International Union of Biochemistry and Molecular Biology, 44(4):326-335, 2016. © 2016 The International Union of Biochemistry and Molecular Biology.

  1. Impact of TIEG1 on the structural properties of fast- and slow-twitch skeletal muscle.

    Science.gov (United States)

    Kammoun, Malek; Meme, Sandra; Meme, William; Subramaniam, Malayannan; Hawse, John R; Canon, Francis; Bensamoun, Sabine F

    2017-03-01

    Transforming growth factor-beta (TGF-β)-inducible early gene-1 (TIEG1) is a transcription factor that is highly expressed in skeletal muscle. The purpose of this study was to characterize the structural properties of both fast-twitch (EDL) and slow-twitch (soleus) muscles in the hindlimb of TIEG1-deficient (TIEG1 -/- ) mice. Ten slow and 10 fast muscles were analyzed from TIEG1 -/- and wild-type (WT) mice using MRI texture (MRI-TA) and histological analyses. MRI-TA could discriminate between WT slow and fast muscles. Deletion of the TIEG1 gene led to changes in the texture profile within both muscle types. Specifically, muscle isolated from TIEG1 -/- mice displayed hypertrophy, hyperplasia, and a modification of fiber area distribution. We demonstrated that TIEG1 plays an important role in the structural properties of skeletal muscle. This study further implicates important roles for TIEG1 in the development of skeletal muscle and suggests that defects in TIEG1 expression and/or function may be associated with muscle disease. Muscle Nerve 55: 410-416, 2017. © 2016 Wiley Periodicals, Inc.

  2. Structural properties of (GaIn)(AsN)/GaAs MQW structures grown by MOVPE

    International Nuclear Information System (INIS)

    Giannini, C.; Carlino, E.; Tapfer, L.; Hoehnsdorf, F.; Koch, J.; Stolz, W.

    2000-01-01

    In this work, the authors investigate the structural properties of (GaIn)(AsN)/GaAs multiple quantum wells (MQW) grown at low temperature by metalorganic vapor phase epitaxy. The structural properties, in particular the In- and N-incorporation, the lattice strain (strain modulation), the structural perfection of the metastable (GaIn)(AsN) material system and the structural quality of the (GaIn)(AsN)/GaAs interfaces are investigated by means of high-resolution x-ray diffraction, transmission electron microscopy (TEM), and secondary ion mass spectrometry. They demonstrate that (GaIn)(AsN) layers of high structural quality can be fabricated up to lattice mismatches of 4%. The experiments reveal that N and In atoms are localized in the quaternary material and no evidences of In-segregation or N-interdiffusion could be found. TEM analyses reveal a low defect density in the highly strained layers, but no clustering or interface undulation could be detected. High-resolution TEM images show that (GaIn)(AsN)/GaAs interfaces are slightly rougher than GaAs/(GaIn)(AsN) ones

  3. The Structural Properties and Stability of Monoclonal Antibodies at Freezing Conditions

    Science.gov (United States)

    Perevozchikova, Tatiana; Zarraga, Isidro; Scherer, Thomas; Wagner, Norman; Liu, Yun

    2013-03-01

    Monoclonal Antibodies (MAb) have become a crucial therapeutic agent in a number of anti-cancer treatments. Due to the inherent unstable nature of proteins in an aqueous formulation, a freeze-drying method has been developed to maintain long-term stability of biotherapeutics. The microstructural changes in Mabs during freezing, however, remain not fully described, and it was proposed that the formed morphology of freeze drying samples could affect the final product quality after reconstitution. Furthermore, it is well known that proteins tend to aggregate during the freezing process if a careful processing procedure is not formulated. Small Angle Neutron Scattering (SANS) is a powerful tool to investigate the structural properties and interactions of Mabs during various stages of lyophilization in situ. Here we present the SANS results of freeze-thaw studies on two MAbs at several different freezing temperatures. While the chosen proteins share a significant sequence homology, their freezing properties are found to be strikingly distinctive. We also show the effect of excipients, concentration and quenching speed on the final morphology of the frozen samples. These findings provide critical information for more effective lyophilization schemes for therapeutic proteins, as well as increase our understanding on structural properties of proteins under cryogenic conditions.

  4. Strontium substituted hydroxyapatites: Synthesis and determination of their structural properties, in vitro and in vivo performance

    Energy Technology Data Exchange (ETDEWEB)

    Kaygili, Omer, E-mail: okaygili@firat.edu.tr [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Keser, Serhat [Department of Chemistry, Faculty of Science, Firat University, 23119 Elazig (Turkey); Kom, Mustafa [Department of Surgery, Faculty of Veterinary Medicine, Firat University, 23119 Elazig (Turkey); Eroksuz, Yesari [Department of Pathology, Faculty of Veterinary Medicine, Firat University, 23119 Elazig (Turkey); Dorozhkin, Sergey V. [Kudrinskaja square 1-155, Moscow 123242 (Russian Federation); Ates, Tankut [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Ozercan, Ibrahim H. [Department of Pathology, School of Medicine, Firat University, 23119 Elazig (Turkey); Tatar, Cengiz; Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey)

    2015-10-01

    The objective of this study is to present a detailed report related to the synthesis and characterization of strontium substituted hydroxyapatites. Based on this purpose, hydroxyapatite (HAp) bioceramics with different amounts of strontium (e.g., 0, 0.45, 0.90, 1.35, 1.80 and 2.25 at.%) were prepared using a sol–gel method. The effects of Sr substitution on the structural properties and biocompatibility of the samples were studied by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, in vitro and in vivo tests. All the samples composed of the nanoparticles ranging from 21 to 27 nm. The presence of Sr at low levels influenced the crystal size, crystallinity degree, lattice parameters and volume of the unit cell of the HAp. Both in vitro conditions and soaking period in simulated body fluid (SBF) significantly affected these properties. Especially, the (Ca + Sr)/P molar ratio gradually decreases with increasing soaking period in SBF. Animal experiments revealed the bone formation and osseointegration for all samples, and as compared with other groups, more reasonable, were observed for the sample with the lowest Sr content. - Highlights: • Sr content affects the structural properties of hydroxyapatite. • Bone formation and osseointegration are observed for all the samples. • In vitro conditions cause a significant change in the (Ca + Sr)/P ratio.

  5. Effect of Spirulina addition on the physicochemical and structural properties of extruded snacks

    Directory of Open Access Journals (Sweden)

    Bárbara Franco LUCAS

    Full Text Available Abstract Nowadays the demand for practical food like snacks increases worldwide, however the nutritional value in most these formulations is reduced. Due to its chemical composition with high protein concentration, the microalga Spirulina has been used on the production of enriched foods. The present study aimed to evaluate the effects of Spirulina sp. LEB 18 addition on snacks formulations and extrusion conditions on the physicochemical and structural properties of snacks. Protein concentration and physical properties such as expansion index, bulk density, hardness, water absorption index, water solubility index and color were determined. The results showed that the addition of Spirulina sp. LEB 18, temperature in the last zone of the extruder and feed moisture influenced the product responses. The increase in feed moisture increased the hardness, bulk density and water absorption index of the snacks. Higher concentrations of microalga produced snacks with higher protein content, total color difference (ΔE and compact structure. The addition of 2.6% Spirulina produced snacks with up to 11.3% protein and with adequate physical and structural properties for consumption. Thus, snacks containing Spirulina are an alternative to the demand for healthy food of practical consumption.

  6. Effect of TEMPO-oxidization and rapid cooling on thermo-structural properties of nanocellulose.

    Science.gov (United States)

    Mhd Haniffa, Mhd Abd Cader; Ching, Yern Chee; Chuah, Cheng Hock; Yong Ching, Kuan; Nazri, Nik; Abdullah, Luqman Chuah; Nai-Shang, Liou

    2017-10-01

    Recently, surface functionality and thermal property of the green nanomaterials have received wide attention in numerous applications. In this study, microcrystalline cellulose (MCC) was used to prepare the nanocrystalline celluloses (NCCs) using acid hydrolysis method. The NCCs was treated with TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl)oxy radical]-oxidation to prepare TEMPO-oxidized NCCs. Cellulose nanofibrils (CNFs) also prepared from MCC using TEMPO-oxidation. The effects of rapid cooling and chemical treatments on the thermo-structural property studies of the prepared nanocelluloses were investigated through FTIR, thermogravimetric analysis-derivative thermogravimetric (TGA-DTG), and XRD. A posteriori knowledge of the FTIR and TGA-DTG analysis revealed that the rapid cooling treatment enhanced the hydrogen bond energy and thermal stability of the TEMPO-oxidized NCC compared to other nanocelluloses. XRD analysis exhibits the effect of rapid cooling on pseudo 2 I helical conformation. This was the first investigation performed on the effect of rapid cooling on structural properties of the nanocellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A Tensile Constitutive Relationship and a Finite Element Model of Electrospun Nanofibrous Mats

    Directory of Open Access Journals (Sweden)

    Yunlei Yin

    2018-01-01

    Full Text Available It is difficult to establish a numerical model for a certain structure of electrospun nanofibrous mats, due to their high porosity and non-linear characteristics, that can fully consider these characteristics and describe their mechanical behaviors. In this paper, an analytical method of meso-mechanics was adopted to establish the tensile constitutive relationship between a single fiber and mats from fiber-web microstructures. Meanwhile, a macroscopic finite element model was developed and verified through uniaxial tensile stress-strain experimental data of silk fibroin (SF/polycaprolactone (PCL nanofibrous mats. The compared results show that the constitutive relation and finite element model could satisfactorily express elastic-plastic tensile mechanical behaviors of the polymer. This model helps regulate the microstructure of nanofibrous mats to meet the mechanical requirements in engineering applications.

  8. A Tensile Constitutive Relationship and a Finite Element Model of Electrospun Nanofibrous Mats.

    Science.gov (United States)

    Yin, Yunlei; Pan, Zhongxiang; Xiong, Jie

    2018-01-08

    It is difficult to establish a numerical model for a certain structure of electrospun nanofibrous mats, due to their high porosity and non-linear characteristics, that can fully consider these characteristics and describe their mechanical behaviors. In this paper, an analytical method of meso-mechanics was adopted to establish the tensile constitutive relationship between a single fiber and mats from fiber-web microstructures. Meanwhile, a macroscopic finite element model was developed and verified through uniaxial tensile stress-strain experimental data of silk fibroin (SF)/polycaprolactone (PCL) nanofibrous mats. The compared results show that the constitutive relation and finite element model could satisfactorily express elastic-plastic tensile mechanical behaviors of the polymer. This model helps regulate the microstructure of nanofibrous mats to meet the mechanical requirements in engineering applications.

  9. The evolution of facility management business models in supplier–client relationships

    DEFF Research Database (Denmark)

    Nardelli, Giulia; Rajala, Risto

    2018-01-01

    Purpose – The study improves the current understanding of business model innovation by outlining how business models unfold over time within supplier–client relationships in facilities management (FM) services. Design/methodology/approach – This study of FM services in Denmark consists...... of an explorative case study and three case studies of facilities management clients. Both phases, related and overlapping, involved collection and analysis of in-depth, semi-structured interviews and archive data. Findings – Findings shows that business model innovation entails interorganisational collaboration...... – This paper suggests that by observing the business models of the value network over time, organisations could learn from the interdependencies between intra- and interorganisational stakeholders, thereby supporting the monitoring of risks and uncertainties as well as the anticipation of potential...

  10. A structural equation model of the relationship between insomnia, negative affect, and paranoid thinking.

    Directory of Open Access Journals (Sweden)

    Alexander J Scott

    Full Text Available A growing body of evidence points to relationships between insomnia, negative affect, and paranoid thinking. However, studies are needed to examine (i whether negative affect mediates the relation between insomnia and paranoid thinking, (ii whether different types of insomnia exert different effects on paranoia, and (iii to compare the impact of objective and self-reported sleeping difficulties.Structural equation modelling was therefore used to test competing models of the relationships between self-reported insomnia, negative affect, and paranoia. n = 348 participants completed measures of insomnia, negative affect and paranoia. A subset of these participants (n = 91 went on to monitor their sleep objectively (using a portable sleep monitor made by Zeo for seven consecutive nights. Associations between objectively recorded sleep, negative affect, and paranoia were explored using linear regression.The findings supported a fully mediated model where self-reported delayed sleep onset, but not self-reported problems with sleep maintenance or objective measures of sleep, was directly associated with negative affect that, in turn, was associated with paranoia. There was no evidence of a direct association between delayed sleep onset or sleep maintenance problems and paranoia.Taken together, the findings point to an association between perceived (but not objective difficulties initially falling asleep (but not maintaining sleep and paranoid thinking; a relationship that is fully mediated by negative affect. Future research should seek to disentangle the causal relationships between sleep, negative affect, and paranoia (e.g., by examining the effect of an intervention using prospective designs that incorporate experience sampling. Indeed, interventions might profitably target (i perceived sleep quality, (ii sleep onset, and / or (iii emotion regulation as a route to reducing negative affect and, thus, paranoid thinking.

  11. IntPath--an integrated pathway gene relationship database for model organisms and important pathogens.

    Science.gov (United States)

    Zhou, Hufeng; Jin, Jingjing; Zhang, Haojun; Yi, Bo; Wozniak, Michal; Wong, Limsoon

    2012-01-01

    Pathway data are important for understanding the relationship between genes, proteins and many other molecules in living organisms. Pathway gene relationships are crucial information for guidance, prediction, reference and assessment in biochemistry, computational biology, and medicine. Many well-established databases--e.g., KEGG, WikiPathways, and BioCyc--are dedicated to collecting pathway data for public access. However, the effectiveness of these databases is hindered by issues such as incompatible data formats, inconsistent molecular representations, inconsistent molecular relationship representations, inconsistent referrals to pathway names, and incomprehensive data from different databases. In this paper, we overcome these issues through extraction, normalization and integration of pathway data from several major public databases (KEGG, WikiPathways, BioCyc, etc). We build a database that not only hosts our integrated pathway gene relationship data for public access but also maintains the necessary updates in the long run. This public repository is named IntPath (Integrated Pathway gene relationship database for model organisms and important pathogens). Four organisms--S. cerevisiae, M. tuberculosis H37Rv, H. Sapiens and M. musculus--are included in this version (V2.0) of IntPath. IntPath uses the "full unification" approach to ensure no deletion and no introduced noise in this process. Therefore, IntPath contains much richer pathway-gene and pathway-gene pair relationships and much larger number of non-redundant genes and gene pairs than any of the single-source databases. The gene relationships of each gene (measured by average node degree) per pathway are significantly richer. The gene relationships in each pathway (measured by average number of gene pairs per pathway) are also considerably richer in the integrated pathways. Moderate manual curation are involved to get rid of errors and noises from source data (e.g., the gene ID errors in WikiPathways and

  12. THE MODERATING EFFECT OF STRENGTH OF MANUFACTURER’S BRANDS ON THE RELATIONSHIP BETWEEN RETAILER’S RELATIONSHIP SATISFACTION AND COMMITMENT: A THEORETICAL MODEL

    Directory of Open Access Journals (Sweden)

    Majid Mapkhot Goaill

    2013-01-01

    Full Text Available Many recent studies emphasized the importance of retailer's satisfaction and commitment to manufacturer/supplier. These studies investigated the relationship between them as an overall relationship. However, there is a dearth of studies that investigated the dimensions of retailer's satisfaction on commitment, and analyzed the mysterious relationship via strength of manufacturer's brands as a moderating effect. Therefore, this study is an attempt to provide a value conceptual model that explains the theoretical linkages existing between dimensions of retailer's satisfaction and commitment, and tries to explain the in-depth meaning of this relationship through the moderating effect of manufacturer's brand strength in the context of social exchange theory. Additionally, hypotheses on the association between the constructs are presented as a basis for further study.

  13. Predictive analysis of the influence of the chemical composition and pre-processing regimen on structural properties of steel alloys using machine learning techniques

    Science.gov (United States)

    Krishnamurthy, Narayanan; Maddali, Siddharth; Romanov, Vyacheslav; Hawk, Jeffrey

    We present some structural properties of multi-component steel alloys as predicted by a random forest machine-learning model. These non-parametric models are trained on high-dimensional data sets defined by features such as chemical composition, pre-processing temperatures and environmental influences, the latter of which are based upon standardized testing procedures for tensile, creep and rupture properties as defined by the American Society of Testing and Materials (ASTM). We quantify the goodness of fit of these models as well as the inferred relative importance of each of these features, all with a conveniently defined metric and scale. The models are tested with synthetic data points, generated subject to the appropriate mathematical constraints for the various features. By this we highlight possible trends in the increase or degradation of the structural properties with perturbations in the features of importance. This work is presented as part of the Data Science Initiative at the National Energy Technology Laboratory, directed specifically towards the computational design of steel alloys.

  14. Adding spatial flexibility to source-receptor relationships for air quality modeling.

    Science.gov (United States)

    Pisoni, E; Clappier, A; Degraeuwe, B; Thunis, P

    2017-04-01

    To cope with computing power limitations, air quality models that are used in integrated assessment applications are generally approximated by simpler expressions referred to as "source-receptor relationships (SRR)". In addition to speed, it is desirable for the SRR also to be spatially flexible (application over a wide range of situations) and to require a "light setup" (based on a limited number of full Air Quality Models - AQM simulations). But "speed", "flexibility" and "light setup" do not naturally come together and a good compromise must be ensured that preserves "accuracy", i.e. a good comparability between SRR results and AQM. In this work we further develop a SRR methodology to better capture spatial flexibility. The updated methodology is based on a cell-to-cell relationship, in which a bell-shape function links emissions to concentrations. Maintaining a cell-to-cell relationship is shown to be the key element needed to ensure spatial flexibility, while at the same time the proposed approach to link emissions and concentrations guarantees a "light set-up" phase. Validation has been repeated on different areas and domain sizes (countries, regions, province throughout Europe) for precursors reduced independently or contemporarily. All runs showed a bias around 10% between the full AQM and the SRR. This methodology allows assessing the impact on air quality of emission scenarios applied over any given area in Europe (regions, set of regions, countries), provided that a limited number of AQM simulations are performed for training.

  15. The relationship between occupational culture dimensions and reward preferences: A structural equation modelling approach

    Directory of Open Access Journals (Sweden)

    Mark Bussin

    2016-02-01

    Full Text Available Orientation: Reward has links to employee attraction and retention and as such has a role to play in managing talent. However, despite a range of research, there is still lack of clarity on employee preferences relating to reward.Research purpose: The purpose of the research was to recommend and appraise a theoretical model of the relationship between occupational culture dimensions and reward preferences of specific occupational groups in the South African context.Motivation for the study: The motivation for this study was to address the gap that exists with reward preferences and occupational culture with a view to identifying and gaining insight into individual preferences.Research design, approach and method: A structural equation modelling approach was adopted in exploring the proposed relationships. A South African Information, Communication, and Technology (ICT organisation served as the population, and a web-based survey assisted in gathering study data (n = 1362.Main findings: The findings provided support for the relationship between occupational culture dimensions and certain reward preferences. In particular, statistically significant results were obtained with the inclusion of the Environment, Team, and Time occupational culture dimensions as independent variables.Practical implications and value-add: The study provides workable input to organisations and reward professionals in the design of their reward strategies and programmes.Keywords: compensation; employee preferences; occupational culture; remuneration; reward preferences

  16. Modelling Inter-relationships among water, governance, human development variables in developing countries with Bayesian networks.

    Science.gov (United States)

    Dondeynaz, C.; Lopez-Puga, J.; Carmona-Moreno, C.

    2012-04-01

    relationships between variable are set a priori according to literature and/or experience in the field (expert knowledge). The statistical validation is verified according to error rate of classification, and the significance of the variables. Sensibility analysis has also been performed to characterise the relative influence of every single variable in the model. Once validated, the models allow the estimation of impact of each variable on the behaviour of the water supply or sanitation providing an interesting mean to test scenarios and predict variables behaviours. The choices made, methods and description of the various models, for each cluster as well as the global model for water supply and sanitation will be presented. Key results and interpretation of the relationships depicted by the models will be detailed during the conference.

  17. Latent variables and structural equation models for longitudinal relationships: an illustration in nutritional epidemiology

    Directory of Open Access Journals (Sweden)

    Basdevant Arnaud

    2010-04-01

    Full Text Available Abstract Background The use of structural equation modeling and latent variables remains uncommon in epidemiology despite its potential usefulness. The latter was illustrated by studying cross-sectional and longitudinal relationships between eating behavior and adiposity, using four different indicators of fat mass. Methods Using data from a longitudinal community-based study, we fitted structural equation models including two latent variables (respectively baseline adiposity and adiposity change after 2 years of follow-up, each being defined, by the four following anthropometric measurement (respectively by their changes: body mass index, waist circumference, skinfold thickness and percent body fat. Latent adiposity variables were hypothesized to depend on a cognitive restraint score, calculated from answers to an eating-behavior questionnaire (TFEQ-18, either cross-sectionally or longitudinally. Results We found that high baseline adiposity was associated with a 2-year increase of the cognitive restraint score and no convincing relationship between baseline cognitive restraint and 2-year adiposity change could be established. Conclusions The latent variable modeling approach enabled presentation of synthetic results rather than separate regression models and detailed analysis of the causal effects of interest. In the general population, restrained eating appears to be an adaptive response of subjects prone to gaining weight more than as a risk factor for fat-mass increase.

  18. The Relationship between Spiritual Health and other Dimensions of Health: Presentation of a Model

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    Akram Heidari

    2016-06-01

    Full Text Available Attitudes to humankind will have different effects on health service delivery. Health might used to be intended to provide physical health in the past; today, however, many researchers and clinicians consider the concept health to be beyond physical health. In support of this claim, it is enough to indicate that the bio-psycho-social model has for years been held by scientific communities to be a fully admitted model. However, the missing ring in this model, as suggested by many, is the spiritual health. In recent years, the relationship between spirituality and clinical interventions with a comprehensive focus on health has been under increasing scrutiny. Although different models have been presented for investigation of the relationship between spiritual health and other dimensions, the fundamental challenge in this regard is the actual place of spiritual health compared with other dimensions. In this article, attempts are made to address the position and weight of spiritual health from the Islam’s point of view.

  19. Positive and Negative Relationship between Anxiety and Depression of Patients in Pain: A Bifactor Model Analysis

    Science.gov (United States)

    li, Wen; Shang, Wen; Yan, Ming; Miao, Danmin; Zhang, Huiming

    2012-01-01

    Background The relationship between anxiety and depression in pain patients has not been clarified comprehensively. Previous research has identified a common factor in anxiety and depression, which may explain why depression and anxiety are strongly correlated. However, the specific clinical features of anxiety and depression seem to pull in opposite directions. Objective The purpose of this study is to develop a statistical model of depression and anxiety, based on data from pain patients using Hospital Anxiety and Depression Scale (HADS). This model should account for the positive correlation between depression and anxiety in terms of a general factor and also demonstrate a latent negative correlation between the specific factors underlying depression and anxiety. Methods The anxiety and depression symptoms of pain patients were evaluated using the HADS and the severity of their pain was assessed with the visual analogue scale (VAS). We developed a hierarchical model of the data using an IRT method called bifactor analysis. In addition, we tested this hierarchical model with model fit comparisons with unidimensional, bidimensional, and tridimensional models. The correlations among anxiety, depression, and pain severity were compared, based on both the bidimensional model and our hierarchical model. Results The bidimensional model analysis found that there was a large positive correlation between anxiety and depression (r = 0.638), and both scores were significantly positively correlated with pain severity. After extracting general factor of distress using bifactor analysis, the specific factors underlying anxiety and depression were weakly but significantly negatively correlated (r = −0.245) and only the general factor was significantly correlated with pain severity. Compared with the three first-order models, the bifactor hierarchical model had the best model fit. Conclusion Our results support the hypothesis that apart from distress, anxiety and

  20. The relationships between internal and external training load models during basketball training.

    Science.gov (United States)

    Scanlan, Aaron T; Wen, Neal; Tucker, Patrick S; Dalbo, Vincent J

    2014-09-01

    The present investigation described and compared the internal and external training loads during basketball training. Eight semiprofessional male basketball players (mean ± SD, age: 26.3 ± 6.7 years; stature: 188.1 ± 6.2 cm; body mass: 92.0 ± 13.8 kg) were monitored across a 7-week period during the preparatory phase of the annual training plan. A total of 44 total sessions were monitored. Player session ratings of perceived exertion (sRPE), heart rate, and accelerometer data were collected across each training session. Internal training load was determined using the sRPE, training impulse (TRIMP), and summated-heart-rate-zones (SHRZ) training load models. External training load was calculated using an established accelerometer algorithm. Pearson product-moment correlations with 95% confidence intervals (CIs) were used to determine the relationships between internal and external training load models. Significant moderate relationships were observed between external training load and the sRPE (r42 = 0.49, 95% CI = 0.23-0.69, p training load and the SHRZ model (r42 = 0.61, 95% CI = 0.38-0.77, p training load models, the magnitude of the correlations and low commonality suggest that internal training load models measure different constructs of the training process than the accelerometer training load model in basketball settings. Basketball coaching and conditioning professionals should not assume a linear dose-response between accelerometer and internal training load models during training and are recommended to combine internal and external approaches when monitoring training load in players.

  1. Quantitative Structure-activity Relationship (QSAR) Models for Docking Score Correction.

    Science.gov (United States)

    Fukunishi, Yoshifumi; Yamasaki, Satoshi; Yasumatsu, Isao; Takeuchi, Koh; Kurosawa, Takashi; Nakamura, Haruki

    2017-01-01

    In order to improve docking score correction, we developed several structure-based quantitative structure activity relationship (QSAR) models by protein-drug docking simulations and applied these models to public affinity data. The prediction models used descriptor-based regression, and the compound descriptor was a set of docking scores against multiple (∼600) proteins including nontargets. The binding free energy that corresponded to the docking score was approximated by a weighted average of docking scores for multiple proteins, and we tried linear, weighted linear and polynomial regression models considering the compound similarities. In addition, we tried a combination of these regression models for individual data sets such as IC 50 , K i , and %inhibition values. The cross-validation results showed that the weighted linear model was more accurate than the simple linear regression model. Thus, the QSAR approaches based on the affinity data of public databases should improve docking scores. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  2. Hipsometric relationship modeling using data sampled in tree scaling and inventory plots

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    Valdir Carlos Lima de Andrade

    2011-02-01

    Full Text Available This work evaluated eight hypsometric models to represent tree height-diameter relationship, using data obtained from the scaling of 118 trees and 25 inventory plots. Residue graphic analysis and percent deviation mean criteria, qui-square test precision, residual standard error between real and estimated heights and the graybill f test were adopted. The identity of the hypsometric models was also verified by applying the F(Ho test on the plot data grouped to the scaling data. It was concluded that better accuracy can be obtained by using the model prodan, with h and d1,3 data measured in 10 trees by plots grouped into these scaling data measurements of even-aged forest stands.

  3. Are animal models useful or confusing in understanding the human feto-maternal relationship? A debate.

    Science.gov (United States)

    Chaouat, Gérard; Clark, David A

    2015-04-01

    The proposition "This house agrees that the proper study of man is woman" was debated. For those negating the proposition, the alternative was that "animal models are useful in understanding the human feto-maternal relationship." Evidence for the proposition emphasized molecular and structural differences between the human and animal placenta and placentation. Evidence against the proposition and in favor of the alternative focused on functional and structural homologies, emphasizing that different molecules could be used in humans to achieve similar functional effects seen in animal (e.g., mouse) models. It was agreed that one always needed to test the validity of animal data by studying humans. The advantages and limitations of animal models were discussed. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Incorporating shape constraints in generalized additive modelling of the height-diameter relationship for Norway spruce

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    Natalya Pya

    2016-02-01

    Full Text Available Background: Measurements of tree heights and diameters are essential in forest assessment and modelling. Tree heights are used for estimating timber volume, site index and other important variables related to forest growth and yield, succession and carbon budget models. However, the diameter at breast height (dbh can be more accurately obtained and at lower cost, than total tree height. Hence, generalized height-diameter (h-d models that predict tree height from dbh, age and other covariates are needed. For a more flexible but biologically plausible estimation of covariate effects we use shape constrained generalized additive models as an extension of existing h-d model approaches. We use causal site parameters such as index of aridity to enhance the generality and causality of the models and to enable predictions under projected changeable climatic conditions. Methods: We develop unconstrained generalized additive models (GAM and shape constrained generalized additive models (SCAM for investigating the possible effects of tree-specific parameters such as tree age, relative diameter at breast height, and site-specific parameters such as index of aridity and sum of daily mean temperature during vegetation period, on the h-d relationship of forests in Lower Saxony, Germany. Results: Some of the derived effects, e.g. effects of age, index of aridity and sum of daily mean temperature have significantly non-linear pattern. The need for using SCAM results from the fact that some of the model effects show partially implausible patterns especially at the boundaries of data ranges. The derived model predicts monotonically increasing levels of tree height with increasing age and temperature sum and decreasing aridity and social rank of a tree within a stand. The definition of constraints leads only to marginal or minor decline in the model statistics like AIC. An observed structured spatial trend in tree height is modelled via 2-dimensional surface

  5. Assessment of source-receptor relationships of aerosols: An integrated forward and backward modeling approach

    Science.gov (United States)

    Kulkarni, Sarika

    This dissertation presents a scientific framework that facilitates enhanced understanding of aerosol source -- receptor (S/R) relationships and their impact on the local, regional and global air quality by employing a complementary suite of modeling methods. The receptor -- oriented Positive Matrix Factorization (PMF) technique is combined with Potential Source Contribution Function (PSCF), a trajectory ensemble model, to characterize sources influencing the aerosols measured at Gosan, Korea during spring 2001. It is found that the episodic dust events originating from desert regions in East Asia (EA) that mix with pollution along the transit path, have a significant and pervasive impact on the air quality of Gosan. The intercontinental and hemispheric transport of aerosols is analyzed by a series of emission perturbation simulations with the Sulfur Transport and dEposition Model (STEM), a regional scale Chemical Transport Model (CTM), evaluated with observations from the 2008 NASA ARCTAS field campaign. This modeling study shows that pollution transport from regions outside North America (NA) contributed ˜ 30 and 20% to NA sulfate and BC surface concentration. This study also identifies aerosols transported from Europe, NA and EA regions as significant contributors to springtime Arctic sulfate and BC. Trajectory ensemble models are combined with source region tagged tracer model output to identify the source regions and possible instances of quasi-lagrangian sampled air masses during the 2006 NASA INTEX-B field campaign. The impact of specific emission sectors from Asia during the INTEX-B period is studied with the STEM model, identifying residential sector as potential target for emission reduction to combat global warming. The output from the STEM model constrained with satellite derived aerosol optical depth and ground based measurements of single scattering albedo via an optimal interpolation assimilation scheme is combined with the PMF technique to

  6. Generalized in vitro-in vivo relationship (IVIVR model based on artificial neural networks

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    Mendyk A

    2013-03-01

    Full Text Available Aleksander Mendyk,1 Pawel Tuszynski,1 Sebastian Polak,2 Renata Jachowicz1 1Department of Pharmaceutical Technology and Biopharmaceutics, 2Department of Social Pharmacy, Faculty of Pharmacy, Jagiellonian University Medical College, Kraków, Poland Background: The aim of this study was to develop a generalized in vitro-in vivo relationship (IVIVR model based on in vitro dissolution profiles together with quantitative and qualitative composition of dosage formulations as covariates. Such a model would be of substantial aid in the early stages of development of a pharmaceutical formulation, when no in vivo results are yet available and it is impossible to create a classical in vitro-in vivo correlation (IVIVC/IVIVR. Methods: Chemoinformatics software was used to compute the molecular descriptors of drug substances (ie, active pharmaceutical ingredients and excipients. The data were collected from the literature. Artificial neural networks were used as the modeling tool. The training process was carried out using the 10-fold cross-validation technique. Results: The database contained 93 formulations with 307 inputs initially, and was later limited to 28 in a course of sensitivity analysis. The four best models were introduced into the artificial neural network ensemble. Complete in vivo profiles were predicted accurately for 37.6% of the formulations. Conclusion: It has been shown that artificial neural networks can be an effective predictive tool for constructing IVIVR in an integrated generalized model for various formulations. Because IVIVC/IVIVR is classically conducted for 2–4 formulations and with a single active pharmaceutical ingredient, the approach described here is unique in that it incorporates various active pharmaceutical ingredients and dosage forms into a single model. Thus, preliminary IVIVC/IVIVR can be available without in vivo data, which is impossible using current IVIVC/IVIVR procedures. Keywords: artificial neural networks

  7. Near-surface turbulence as a missing link in modeling evapotranspiration-soil moisture relationships

    Science.gov (United States)

    Haghighi, Erfan; Kirchner, James W.

    2017-07-01

    Despite many efforts to develop evapotranspiration (ET) models with improved parametrizations of resistance terms for water vapor transfer into the atmosphere, estimates of ET and its partitioning remain prone to bias. Much of this bias could arise from inadequate representations of physical interactions near nonuniform surfaces from which localized heat and water vapor fluxes emanate. This study aims to provide a mechanistic bridge from land-surface characteristics to vertical transport predictions, and proposes a new physically based ET model that builds on a recently developed bluff-rough bare soil evaporation model incorporating coupled soil moisture-atmospheric controls. The newly developed ET model explicitly accounts for (1) near-surface turbulent interactions affecting soil drying and (2) soil-moisture-dependent stomatal responses to atmospheric evaporative demand that influence leaf (and canopy) transpiration. Model estimates of ET and its partitioning were in good agreement with available field-scale data, and highlight hidden processes not accounted for by commonly used ET schemes. One such process, nonlinear vegetation-induced turbulence (as a function of vegetation stature and cover fraction) significantly influences ET-soil moisture relationships. Our results are particularly important for water resources and land use planning of semiarid sparsely vegetated ecosystems where soil surface interactions are known to play a critical role in land-climate interactions. This study potentially facilitates a mathematically tractable description of the strength (i.e., the slope) of the ET-soil moisture relationship, which is a core component of models that seek to predict land-atmosphere coupling and its feedback to the climate system in a changing climate.

  8. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Trong D. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Hudson, Matthew R. [Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Brown, Craig M. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Lobo, Raul F. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA

    2017-02-16

    The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol-1). Mg2+ was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2, leading to a much lower Qst (ca. 30 kJ mol-1) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li+ and Mg2+ cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2.

  9. An in-situ analytical scanning and transmission electron microscopy investigation of structure-property relationships in electronic materials

    Science.gov (United States)

    Wagner, Andrew James

    As electronic and mechanical devices are scaled downward in size and upward in complexity, macroscopic principles no longer apply. Synthesis of three-dimensionally confined structures exhibit quantum confinement effects allowing, for example, silicon nanoparticles to luminesce. The reduction in size of classically brittle materials reveals a ductile-to-brittle transition. Such a transition, attributed to a reduction in defects, increases elasticity. In the case of silicon, elastic deformation can improve electronic carrier mobility by over 50%, a vital attribute of modern integrated circuits. The scalability of such principles and the changing atomistic processes which contribute to them presents a vitally important field of research. Beginning with the direct observation of dislocations and lattice planes in the 1950s, the transmission electron microscope has been a powerful tool in materials science. More recently, as nanoscale technologies have proliferated modern life, their unique ability to spatially resolve nano- and atomic-scale structures has become a critical component of materials research and characterization. Signals produced by an incident beam of high-energy electrons enables researchers to both image and chemically analyze materials at the atomic scale. Coherently and elastically-scattered electrons can be collected to produce atomic-scale images of a crystalline sample. New specimen stages have enabled routine investigation of samples heated up to 1000 °C and cooled to liquid nitrogen temperatures. MEMS-based transducers allow for sub-nm scale mechanical testing and ultrathin membranes allow study of liquids and gases. Investigation of a myriad of previously "unseeable" processes can now be observed within the TEM, and sometimes something new is found within the old. High-temperature annealing of pure a Si:H films leads to crystallization of the film. Such films provide higher carrier mobility compared to amorphous films, offering improved photovoltaic performance. The annealing process, however, requires exceptionally high temperature (> 600 °C) and time (tens of hours), limiting throughput and costing energy. In an effort to fabricate polycrystalline solar cells at lower cost, large ( 30 nm) silicon nanocrystals were incorporated into hydrogenated amorphous silicon (a Si:H) thin films. When annealed, the embedded nanocrystals were expected to act as heterogeneous nucleation sites and crystallize the surrounding amorphous matrix. When observed in the TEM, an additional and unexpected event was observed. At the boundary between the nanocrystal and amorphous matrix, nanocavities were observed to form. Continued annealing resulted in movement of the cavities away from the nanocrystal while leaving behind a crystalline tail. The origins and fundamental mechanisms of this phenomenon were examined by in-situ heating TEM and ex-situ crystallographic TEM techniques. We demonstrate a mechanism of solid-phase crystallization (SPC) enabled by nanoscale cavities formed at the interface between an hydrogenated amorphous silicon film and embedded 30 nm to 40 nm Si nanocrystals. The nanocavities, 10 nm to 25 nm across, have the unique property of an internal surface that is part amorphous and part crystalline, enabling capillarity-driven diffusion from the amorphous to the crystalline domain. The nanocavities propagate rapidly through the amorphous phase, up to five times faster than the SPC growth rate, while "pulling behind" a crystalline tail. It is shown that twin boundaries exposed on the crystalline surface accelerate crystal growth and influence the direction of nanocavity propagation. The mechanical properties and mechanisms of plasticity in these same silicon nanocubes have also been investigated. The strain-dependent mechanical properties and the underlying mechanisms governing the elastic-plastic response are explored in detail. Elastic strains approaching 7% and flow stresses of 11 GPa were observed, significantly higher than that observed in other nanoscale volumes of Si. In-situ imaging revealed the formation of 5 nm dislocation embryos at 7% strain, giving way at 20% strain to continuous nucleation of leading partial dislocations with {111}-habit at the embryo surface.

  10. Rational interface design of epoxy-organoclay nanocomposites: role of structure-property relationship for silane modifiers.

    Science.gov (United States)

    Bruce, Alex N; Lieber, Danielle; Hua, Inez; Howarter, John A

    2014-04-01

    Montmorillonite was modified by three silane surfactants with different functionalities to investigate the role of surfactant structure on the properties of a final epoxy-organoclay nanocomposite. N-aminopropyldimethylethoxysilane (APDMES), an aminated monofunctional silane, was chosen as a promising surfactant for several reasons: (1) it will bond to silica in montmorillonite, (2) it will bond to epoxide groups, and (3) to overcome difficulties found with trifunctional aminosilane bonding clay layers together and preventing exfoliation. A trifunctional and non-aminated version of APDMES, 3-aminopropyltriethoxysilane (APTES) and n-propyldimethylmethoxysilane (PDMMS), respectively, was also studied to provide comparison to this rationally chosen surfactant. APDMES and APTES were grafted onto montmorillonite in the same amount, while PDMMS was barely grafted (silane surfactant, neat epoxy, and epoxy-montmorillonite nanocomposite. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Land-Use and Land-Management Change: Relationships with Earthworm and Fungi Communities and Soil Structural Properties

    NARCIS (Netherlands)

    Spurgeon, D.J.; Keith, A.M.; Schmidt, O.; Lammertsma, D.R.; Faber, J.H.

    2013-01-01

    Background Change in land use and management can impact massively on soil ecosystems. Ecosystem engineers and other functional biodiversity in soils can be influenced directly by such change and this in turn can affect key soil functions. Here, we employ meta-analysis to provide a quantitative

  12. Structure-Property Relationships in Surface-Modified Ceramics. NATO advanced Science Institutes, Series E: Applied Sciences, Volume 170

    Science.gov (United States)

    1989-01-01

    2600 2500 2400 FIGURE 8. Infrared transmission spectra ( FTIR ) of rutile implanted with 50 keV deuterons at various doses: (a) before implantation; (b...to the penetration depth affects the inden - tation hardness measurements. For an ideal plastic material, the highest 261 MODULUS CHANGES DUE TO ION...Finally, the shallow indents made under low loads may exhibit the inden - tation size effect (ISE). The physical picture of the ISE is not understood

  13. Investigating The Relationship Between Flourishing And Self-Compassion: A Structural Equation Modeling Approach

    Directory of Open Access Journals (Sweden)

    Seydi Ahmet Satici

    2013-12-01

    Full Text Available The purpose of this study was to examine the relationships between flourishing and self-compassion. Participants were 347 (194 female and 153 male university students, between age range of 18-24, who completed a questionnaire package that included the Flourishing Scale and the Self-compassion Scale. The relationships between flourishing and self-compassion were examined using correlation analysis and the hypothesis model was tested through structural equation modeling. In correlation analysis, self-kindness, common humanity, and mindfulness factors of self-compassion were found positively and self-judgment, isolation, and over-identification factors of self-compassion were found negatively related to flourishing. The model demonstrated fit (χ²=37.12, χ²/df = 4.12, RMSEA = .095, SRMR = .074, GFI = .97, AGFI = .91, CFI= .97, and NFI = .96. According to path analysis results, self-kindness, common humanity, and mindfulness were predicted positively by flourishing. Further, flourishing predicted self-judgment, isolation, and over-identification in a negative way. Results were discussed in the light of the related literature.

  14. Modelling the relationship between water level and vertical displacements on the Yamula Dam, Turkey

    Directory of Open Access Journals (Sweden)

    T. Bayrak

    2007-01-01

    Full Text Available Monitoring deformation pattern of dams is often one of the most effective ways to understand their safety status. The main objective of the study is to find the extent to which rising reservoir level affects the mechanism of deformation of The Yamula Dam under certain change in the reservoir level conditions during to the first filling period. Three different deformation analysis techniques, namely static, kinematic and dynamic, were used to analyze four geodetic monitoring records consisting of vertical displacements of nine object points established on the Dam and six reference points surrounding of it, to see whether the rising reservoir level have a role in the vertical deformations during the first filling period. The largest vertical displacements were in the middle of the dam. There is an apparent linear relationship between the dam subsidence and the reservoir level. A dynamic deformation model was developed to model this situation. The model infers a causative relationship between the reservoir level and the dam deformations. The analysis of the results determines the degree of the correlation between the change in the reservoir level and the observed structural deformation of the dam.

  15. Modeling the Structure of the Relationship Between Emotion Regulation Difficulties, Positive and Negative affect Sleep Quality

    Directory of Open Access Journals (Sweden)

    S Amiri

    2017-05-01

    Full Text Available Abstract   Background & aim: Poor quality sleep is very common in modern societies and has a significant negative impact on psychological and physiological Dimensions. The purpose of the present study was to investigate correlational relationships and draw up a positive and negative affect mediation model between the difficulty in regulation of emotion and quality of sleep.   Methods: In this descriptive-correlational study, the participants of the study were selected through multi-stage cluster sampling. Then, the difficulty questionnaire was distributed in emotion regulation, affective and negative and sleep quality among the participants . Collected data was analyzed for descriptive, correlation, structural equation modeling to investigate the research objectives.   Results: The results showed that there was a significant positive correlation between the difficulty components of emotion regulation and negative emotion with poor sleep quality and positive correlation between positive affection and high sleep quality (p <0.01. Also, the pattern of structural equation modeling indicates the role of mediating positive and negative affects in the relationship between the difficulty in regulation of emotion and sleep quality . Conclusions: The results supported the hypothesis that the difficulty in regulation of emotion interferes with the quality of sleep, and positive affection can have a moderating role in this regard.    

  16. Development and Validation of Quantitative Structure-Activity Relationship Models for Compounds Acting on Serotoninergic Receptors

    Directory of Open Access Journals (Sweden)

    Grażyna Żydek

    2012-01-01

    Full Text Available A quantitative structure-activity relationship (QSAR study has been made on 20 compounds with serotonin (5-HT receptor affinity. Thin-layer chromatographic (TLC data and physicochemical parameters were applied in this study. RP2 TLC 60F254 plates (silanized impregnated with solutions of propionic acid, ethylbenzene, 4-ethylphenol, and propionamide (used as analogues of the key receptor amino acids and their mixtures (denoted as S1–S7 biochromatographic models were used in two developing phases as a model of drug-5-HT receptor interaction. The semiempirical method AM1 (HyperChem v. 7.0 program and ACD/Labs v. 8.0 program were employed to calculate a set of physicochemical parameters for the investigated compounds. Correlation and multiple linear regression analysis were used to search for the best QSAR equations. The correlations obtained for the compounds studied represent their interactions with the proposed biochromatographic models. The good multivariate relationships (R2=0.78–0.84 obtained by means of regression analysis can be used for predicting the quantitative effect of biological activity of different compounds with 5-HT receptor affinity. “Leave-one-out” (LOO and “leave-N-out” (LNO cross-validation methods were used to judge the predictive power of final regression equations.

  17. Physico-mechanical and structural properties of eggshell membrane gelatin- chitosan blend edible films.

    Science.gov (United States)

    Mohammadi, Reza; Mohammadifar, Mohammad Amin; Rouhi, Milad; Kariminejad, Mohaddeseh; Mortazavian, Amir Mohammad; Sadeghi, Ehsan; Hasanvand, Sara

    2018-02-01

    This study investigated the physico-mechanical and structural properties of composite edible films based on eggshell membrane gelatin (G) and chitosan (Ch) (75G:25Ch, 50G:50Ch, 25G:75Ch). The results demonstrated that the addition of Ch increased elongation at break significantly (pfilm. The water solubility and water vapor permeability of the 50G:50Ch film decreased significantly compared to plain films (100G:0Ch and 0G:100Ch) and other composite films (pfilms; it revealed a homogenous and compact structure in 75G:25Ch and 50G:50 Ch. Also, the chemical interactions introduced by the addition of chitosan to eggshell membrane gelatin as new resources could improve the films' functional properties. Copyright © 2017. Published by Elsevier B.V.

  18. Influence of iron ions on the structural properties of some inorganic glasses

    International Nuclear Information System (INIS)

    Music, S.; Gotic, M.; Popovic, S.; Grzeta, B.

    1987-01-01

    The effects of iron on the structural properties of Zn-borosilicate glass and Pb-metaphosphate glass were studied using x-ray diffraction, 57 Fe Moessbauer spectroscopy and IR spectroscopy. At high concentration of iron the crystallization of zinc ferrite in the glass matrix takes place. X-ray diffraction and 57 Fe Moessbauer spectroscopy showed that the amount of zinc ferrite in Zn-borosilicate glass decreases. In Pb-metaphosphate glass doped with high concentration of α-Fe 2 O 3 , the crystallization of Fe 3 (PO 4 ) 2 is pronounced. The assignments of IR band positions and the corresponding interpretation are given. The importance of this study for the technology of vitrification of high-level radioactive wastes is emphasized. (author) 31 refs.; 6 figs,.; 6 tabs

  19. Structures, properties, and functions of the stings of honey bees and paper wasps: a comparative study

    Directory of Open Access Journals (Sweden)

    Zi-Long Zhao

    2015-07-01

    Full Text Available Through natural selection, many animal organs with similar functions have evolved different macroscopic morphologies and microscopic structures. Here, we comparatively investigate the structures, properties and functions of honey bee stings and paper wasp stings. Their elegant structures were systematically observed. To examine their behaviors of penetrating into different materials, we performed penetration–extraction tests and slow motion analyses of their insertion process. In comparison, the barbed stings of honey bees are relatively difficult to be withdrawn from fibrous tissues (e.g. skin, while the removal of paper wasp stings is easier due to their different structures and insertion skills. The similarities and differences of the two kinds of stings are summarized on the basis of the experiments and observations.

  20. Effect of Operating Temperature on Structure Properties of TICX Nanoparticle Coating Applied by Pacvd

    Science.gov (United States)

    Shanaghi, Ali; Sabour Rouhaghdam, Ali Reza; Ahangarani, Shahrokh; Moradi, Hadi; Mohammadi, Ali

    Titanium carbide (TiC) is a widely used hard coating to improve the wear resistance and lifetime of tools because of its outstanding properties such as high melting point, high hardness, corrosion resistance and abrasion resistance. These properties were drastically improved by using nanotechnology. So in this project, TiCx was applied on hot-working die steel (H11) by Plasma CVD (PACVD). The effect of operating temperatures on TiCx structure properties have been studies by typical and advanced analyses methods such as SEM, XRD, FTIR and Raman. The best properties of TiCx nanoparticle, such as nanostructure, mechanical properties and chemical properties, were obtained at 480 °C.

  1. Effect of Fe2O3 on the physical and structural properties of bismuth silicate glasses

    Science.gov (United States)

    Parmar, Rajesh; Kundu, R. S.; Punia, R.; Aghamkar, P.; Kishore, N.

    2013-06-01

    Iron containing bismuth silicate glasses with compositions 70SiO2ṡ(100-x)Bi2O3ṡxFe2O3 have been prepared using conventional melt-quenching method and their amorphous nature has been investigated using XRD. Density has been measured using Archimedes' principle and molar volume (Vm) have also been estimated. With increase in Fe2O3 content, there is a decrease in density and molar volume of the glass samples. The glass transition temperature (Tg) have been determined using Differential Scanning Calorimetry (DSC) and are observed to increase with increase in Fe2O3 content. In the present glass system bismuth and iron plays the role of network modifier and the symmetry of silicate network goes on increasing with Fe2O3 content and it modifies the physical and structural properties of these glasses.

  2. Influence of substrate orientation on the structural properties of GaAs nanowires in MOCVD

    International Nuclear Information System (INIS)

    Muhammad, R.; Othaman, Z.; Ibrahim, Z.; Sakrani, S.; Wahab, Y.

    2016-01-01

    In this study, the effect of substrate orientation on the structural properties of GaAs nanowires grown by a metal organic chemical vapor deposition has been investigated. Gold colloids were used as catalyst to initiate the growth of nanowiresby the vapour-liquid-solid (VLS) mechanism. From the field-emission scanning electron microscopy (FE-SEM), the growth of the nanowires were at an elevation angle of 90°, 60°, 65° and 35° with respect to the GaAs substrate for (111)B, (311)B, (110) and (100) orientations respectively. The preferential NW growth direction is always <111>B. High-resolution transmission electron microscope (HRTEM) micrograph showed the NWs that grew on the GaAs(111)B has more structural defects when compared to others. Energy dispersive X-ray analysis (EDX) indicated the presence of Au, Ga and As. The bigger diameter NWs dominates the (111)B substrate surface.

  3. Optical and structural properties of MOVPE-grown GaInSb/GaSb quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, Viera, E-mail: viera.wagener@nmmu.ac.z [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Olivier, E.J.; Botha, J.R. [Physics Department, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2009-12-15

    This paper reports on the optical and structural properties of strained type-I Ga{sub 1-x}In{sub x}Sb quantum wells embedded in GaSb from a metal-organic vapour phase epitaxial growth perspective. Photoluminescence measurements and transmission electron microscopy were used to evaluate the effect of the growth temperature on the quality of Ga{sub 1-x}In{sub x}Sb strained layers with varied alloy compositions and thicknesses. Although the various factors contributing to the overall quality of the strained layers are difficult to separate, the quantum well characteristics are significantly altered by the growth temperature. Despite the high growth rates (approx2 nm/s), quantum wells grown at 607 deg. C display photoluminescence emissions with full-width at half-maximum of 3.5-5.0 meV for an indium solid content (x) up to 0.15.

  4. Optical and structural properties of MOVPE-grown GaInSb/GaSb quantum wells

    International Nuclear Information System (INIS)

    Wagener, Viera; Olivier, E.J.; Botha, J.R.

    2009-01-01

    This paper reports on the optical and structural properties of strained type-I Ga 1-x In x Sb quantum wells embedded in GaSb from a metal-organic vapour phase epitaxial growth perspective. Photoluminescence measurements and transmission electron microscopy were used to evaluate the effect of the growth temperature on the quality of Ga 1-x In x Sb strained layers with varied alloy compositions and thicknesses. Although the various factors contributing to the overall quality of the strained layers are difficult to separate, the quantum well characteristics are significantly altered by the growth temperature. Despite the high growth rates (∼2 nm/s), quantum wells grown at 607 deg. C display photoluminescence emissions with full-width at half-maximum of 3.5-5.0 meV for an indium solid content (x) up to 0.15.

  5. Low-temperature oxidation effects on the morphological and structural properties of hexagonal Zn nano disks

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, R.; Villa S, G.; Rosales D, J. [Tecnologico de Estudios Superiores de Jocotitlan, Carretera Toluca-Atlacomulco Km 44.8, Jocotitlan, Estado de Mexico (Mexico); Vigueras S, E.; Hernandez L, S. [Universidad Autonoma del Estado de Mexico, Laboratorio de Investigacion y Desarrollo de Materiales Avanzados, Paseo Colon esquina Paseo Tollocan, Toluca, Estado de Mexico (Mexico); Acuna, P. [Universidad Autonoma del Estado de Mexico, Programa de Doctorado en Ciencia de Materiales, Paseo Colon esquina Paseo Tollocan, Toluca, Estado de Mexico (Mexico); Argueta V, A.; Colin B, N., E-mail: lorr810813@gmail.com [Tecnologico de Estudios Superiores de Jocotitlan, Programa de Ingenieria Mecatronica, Carretera Toluca-Atlacomulco Km 44.8, Jocotitlan, Estado de Mexico (Mexico)

    2017-11-01

    Ambient-atmosphere oxidation in the temperature range of 90-450 degrees Celsius was performed over Zn films composed by well-faceted hexagonal nano disks, which were deposited by thermal evaporation. Morphological and structural properties of oxidized Zn nano disks were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering measurements. It was found that Zn nano disks keep its original shape only when they are annealed at 90 or 150 degrees Celsius. Smooth oxidation occurred only on the rectangular faces of Zn nano disks heated at 150 degrees Celsius. Thermal oxidation at 250 degrees Celsius favored growth of Zn O nano needles over the surface of the Zn nano disks. Hexagonal-shape of Zn nano disks was transformed completely into a complex morphology composed by different shaped particles, with further increase in oxidation temperature to 450 degrees Celsius. (Author)

  6. Low-temperature oxidation effects on the morphological and structural properties of hexagonal Zn nano disks

    International Nuclear Information System (INIS)

    Lopez, R.; Villa S, G.; Rosales D, J.; Vigueras S, E.; Hernandez L, S.; Acuna, P.; Argueta V, A.; Colin B, N.

    2017-01-01

    Ambient-atmosphere oxidation in the temperature range of 90-450 degrees Celsius was performed over Zn films composed by well-faceted hexagonal nano disks, which were deposited by thermal evaporation. Morphological and structural properties of oxidized Zn nano disks were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Raman scattering measurements. It was found that Zn nano disks keep its original shape only when they are annealed at 90 or 150 degrees Celsius. Smooth oxidation occurred only on the rectangular faces of Zn nano disks heated at 150 degrees Celsius. Thermal oxidation at 250 degrees Celsius favored growth of Zn O nano needles over the surface of the Zn nano disks. Hexagonal-shape of Zn nano disks was transformed completely into a complex morphology composed by different shaped particles, with further increase in oxidation temperature to 450 degrees Celsius. (Author)

  7. Pb1–xMnxTe single crystals and their structural properties

    Directory of Open Access Journals (Sweden)

    NEBOJSA ROMCEVIC

    2004-12-01

    Full Text Available Pb1-xMnxTe crystals were grown by the vertical Bridgman method. Their structural properties were observed both by optical microscopy after chemical polishing and ething, and by X-ray powder diffraction analysis. A solution of 5 vol. % Br2 in HBr at room temperatur, for an exposure of 2 min was determined for chemical polishing. A solution of 20 g KOH in 1 ml H2O2, 2 ml glycerol (C3H8O3, and 20 ml H2O at room temperature for an exposure for 6 min was found to be a suitable etching solution. The obtained results are discussed and compared with published data.

  8. Scientific activity within the targeted research project: Metallic, ceramic and organic nanomaterials: processing - structure - properties - applications

    International Nuclear Information System (INIS)

    Leonowicz, M.; Kurzydlowski, K.

    2003-01-01

    In november 2000 Polish State Committee for Scientific Research (KBN) launched a Targeted Research Project 'Metallic, ceramic and organic nanomaterials: processing - structure - properties - applications'. The structural materials, covered by the project, comprise analysis of the suitability of heavy deformation routes for nanocrystallization of metals and alloys, Al-based glass-ceramics, ceramic matrix nanocomposites, gradient materials. Also surface engineering methods and polymer matrix nanocomposites are studied. Novel methods for the processing and compacting of nanomaterials are also researched. Among functional materials: materials for batteries soft and hard magnetic materials and nanomaterials, giant magnetoresistance and light emitting materials are studied. Basic phenomena such as mechanics of superplastic deformation of ceramics, demagnetization processes in ferromagnetic nanomaterials, transport processes in ionic conductivity materials are also investigated. Overview of the main research direction and selected achievements of the project are presented. (author)

  9. Sulfated tin oxide (STO – Structural properties and application in catalysis: A review

    Directory of Open Access Journals (Sweden)

    Ravi Varala

    2016-07-01

    Full Text Available Catalysis is an important area of chemistry, with an extensive amount of work going on in this area of sciences, toward synthesis and evaluation of newer catalysts. There are many reports for different conversion reactions such as oxidation, reduction, coupling, alkylation, and acylation for which various catalysts have been used such as mixed metal oxides, metal nanoparticles, metal organic complexes and many others. Among the many catalysts reported, the one catalyst that caught our attention due to its exploitation for a plethora of organic conversions is the sulfated tin oxide (STO, which is due to the low cost, greater stability and high efficiency of the catalyst. In this review, we have attempted to compile data about the structural properties of STO, and its applications as catalysts in various organic synthesis are presented. The literature data up to 2014 were collected and considered for the review.

  10. The effects of 7-dehydrocholesterol on the structural properties of membranes

    Science.gov (United States)

    Liu, Yingzhe; Chipot, Christophe; Shao, Xueguang; Cai, Wensheng

    2011-10-01

    Smith-Lemli-Opitz syndrome, a congenital and developmental malformation disease, is typified by abnormal accumulation of 7-dehydrocholesterol (7DHC), the immediate precursor of cholesterol (CHOL), and depletion thereof. Knowledge of the effect of 7DHC on the biological membrane is, however, still fragmentary. In this study, large-scale atomistic molecular dynamics simulations, employing two distinct force fields, have been conducted to elucidate differences in the structural properties of a hydrated dimyristoylphosphatidylcholine bilayer due to CHOL and 7DHC. The present series of results indicate that CHOL and 7DHC possess virtually the same ability to condense and order membranes. Furthermore, the condensing and ordering effects are shown to be strengthened at increasing sterol concentrations.

  11. Optical and Structural Properties of MEH-PPV: ZnO Nano composites

    International Nuclear Information System (INIS)

    Nurul Zayana Yahya; Mohamad Rusop; Mohamad Rusop

    2011-01-01

    Thin films of conducting unsaturated polymer of red color poly [2- methoxy-5(2-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV) containing different weight percent of ZnO nanoparticles were deposited by spin coating techniques. The MEH-PPV: ZnO solutions were spin coated onto glass substrates. The spun MEH-PPV: ZnO thin films were used for investigating the optical properties by using Ultraviolet-Visible Spectrometer (UV-Vis). The structural properties of the thin films were investigated by Scanning Electron Microscopy (SEM). For MEH-PPV: ZnO nano composites, the UV-Vis absorption bands increases and showing slight blue shift compared to the pure MEH-PPV. From the SEM images of some MEH-PPV: ZnO nano composites, it can be seen that ZnO nanoparticles form aggregated regions. (author)

  12. Influence of substrate orientation on the structural properties of GaAs nanowires in MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, R., E-mail: rosnita@utm.my; Othaman, Z., E-mail: zulothaman@gmail.com; Ibrahim, Z., E-mail: zuhairi@utm.my; Sakrani, S., E-mail: samsudi3@yahoo.com [Faculty of Science, UniversitiTeknologi Malaysia, 81310 UTM, Johor (Malaysia); Wahab, Y., E-mail: wyussof@gmail.com [Razak School, UniversitiTeknologi Malaysia, 54100 Kuala Lumpur (Malaysia)

    2016-04-19

    In this study, the effect of substrate orientation on the structural properties of GaAs nanowires grown by a metal organic chemical vapor deposition has been investigated. Gold colloids were used as catalyst to initiate the growth of nanowiresby the vapour-liquid-solid (VLS) mechanism. From the field-emission scanning electron microscopy (FE-SEM), the growth of the nanowires were at an elevation angle of 90°, 60°, 65° and 35° with respect to the GaAs substrate for (111)B, (311)B, (110) and (100) orientations respectively. The preferential NW growth direction is always <111>B. High-resolution transmission electron microscope (HRTEM) micrograph showed the NWs that grew on the GaAs(111)B has more structural defects when compared to others. Energy dispersive X-ray analysis (EDX) indicated the presence of Au, Ga and As. The bigger diameter NWs dominates the (111)B substrate surface.

  13. Blending protocol effect in structural properties of PA6/ABS nanocomposites compatibilized with SAN-MA

    International Nuclear Information System (INIS)

    Castro, Lucas D.C. de; Oliveira, Amanda D.; Pessan, Luiz Antonio

    2015-01-01

    Nanocomposites based on polyamide 6 (PA6) and acrylonitrile-butadiene-styrene (ABS) compatibilized with styrene acrylonitrile-co-maleic anhydride were prepared using different blending protocols in a twin screw extruder. Specimen were prepared though injection molding. The organoclay (OMMT) incorporation and blending sequence effect on structural properties were investigated. X-ray diffraction analysis (XRD) indicates a complete exfoliated structure for all samples. Rheological measurements show an increasing in nanocomposites complex viscosities and storage modulus values when compared with the ternary blend. However, no significant effects in the rheological behavior were observed due the blending sequence. Differential scanning calorimetry (DSC) measurements suggests the incorporation of OMMT and different blending protocols may influence the polyamide polymorphism and degree of crystallinity. (author)

  14. Molecular and structural properties of polymer composites filled with activated charcoal particles

    Science.gov (United States)

    Tahir, Dahlang; Liong, Syarifuddin; Bakri, Fahrul

    2016-03-01

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH3) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO3, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  15. Molecular and structural properties of polymer composites filled with activated charcoal particles

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul [Department of Physics, Hasanuddin University, Makassar 90245 Indonesia (Indonesia); Liong, Syarifuddin [Department of Chemistry, Hasanuddin University, Makassar 90245 Indonesia (Indonesia)

    2016-03-11

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  16. Characterization of wami tilapia (Oreochromis urolepis hornorum) skin gelatin: microbiological, rheological and structural properties.

    Science.gov (United States)

    Alfaro, Alexandre Da Trindade; Fonseca, Gustavo Graciano; Balbinot, Evellin; Prentice, Carlos

    2014-07-01

    Gelatin was extracted from the skin of tilapia (Oreochromis urolepis hornorum) and its microbiological, rheological and structural properties were characterized. The tilapia skin gelatin presented typical molecular weight distribution of type I collagen with contents of imino acids (proline + hydroxyproline) of 21.67%. Gel strength and viscosity values were 221 ± 5.68 g and 5.98 ± 0.34 cP, respectively, with the maturation time of 18 ± 1 h, and both parameters increased with the maturation time. Melting and gelling points of 25 degrees C and 21 degrees C, respectively, were obtained for tilapia skin gelatin. The gelatin presented microbiological standards in accordance with the Brazilian Legislation.

  17. Photo-responsive carbon nanomaterials functionalized by azobenzene moieties: structures, properties and application.

    Science.gov (United States)

    Feng, Wei; Luo, Wen; Feng, Yiyu

    2012-10-21

    The ability to tune the microstructures, bandgap, conductance, chemical environment and thermal storage of carbon nanomaterials such as carbon nanotubes, graphene and fullerenes by optical modulation or response is important to design and fabricate advanced optoelectronic nanodevices. This review is focused on optical control and regulation of structures, properties, interface and interaction of a new generation of photo-responsive carbon nanomaterials/azobenzene moieties (Carbon-AZO) hybrids. The optical switching properties of Carbon-AZO hybrids resulting from the photo-isomerization between trans and cis isomers are highlighted and discussed in terms of photo-energy conversion devices including switches, sensors, detectors, fuels and storage. A wide range of advanced energy conversion devices using Carbon-AZO hybrids can be developed in the future by the optimization of the chemical structure, steric conformation, electrostatic environment and functionalization of specific molecules.

  18. Structure Properties and Mechanisms of Action of Naturally Originated Phenolic Acids and Their Derivatives against Human Viral Infections.

    Science.gov (United States)

    Wu, Yi-Hang; Zhang, Bing-Yi; Qiu, Li-Peng; Guan, Rong-Fa; Ye, Zi-Hong; Yu, Xiao-Ping

    2017-01-01

    A great effort has been made to develop efficacious antiviral drugs, but many viral infections are still lack of efficient antiviral therapies so far. The related exploration of natural products to fight viruses has been raised in recent years. Natural compounds with structural diversity and complexity offer a great chance to find new antiviral agents. Particularly, phenolic acids have attracted considerable attention owing to their potent antiviral abilities and unique mechanisms. The aim of this review is to report new discoveries and updates pertaining to antiviral phenolic acids. The relevant references on natural phenolic acids were searched. The antiviral phenolic acids were classified according to their structural properties and antiviral types. Meanwhile, the antiviral characteristics and structure-activity relationships of phenolic acids and their derivatives were summarized. The review finds that natural phenolic acids and their derivatives possessed potent inhibitory effects on multiple virus in humans such as human immunodeficiency virus, hepatitis C virus, hepatitis B virus, herpes simplex virus, influenza virus and respiratory syncytial virus. In particular, caffeic acid/gallic acid and their derivatives exhibited outstanding antiviral properties by a variety of modes of action. Naturally derived phenolic acids especially caffeic acid/gallic acid and their derivatives may be regarded as novel promising antiviral leads or candidates. Additionally, scarcely any of these compounds has been used as antiviral treatment in clinical practice. Therefore, these phenolic acids with diverse skeletons and mechanisms provide us an excellent resource for finding novel antiviral drugs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  19. Bridging Theory and Experiment to Address Structural Properties of Truncated Haemoglobins: Insights from Thermobifida fusca HbO.

    Science.gov (United States)

    Howes, Barry D; Boechi, Leonardo; Boffi, Alberto; Estrin, Dario E; Smulevich, Giulietta

    2015-01-01

    In this chapter, we will discuss the paradigmatic case of Thermobifida fusca (Tf-trHb) HbO in its ferrous and ferric states and its behaviour towards a battery of possible ligands. This choice was dictated by the fact that it has been one of the most extensively studied truncated haemoglobins, both in terms of spectroscopic and molecular dynamics studies. Tf-trHb typifies the structural properties of group II trHbs, as the active site is characterized by a highly polar distal environment in which TrpG8, TyrCD1, and TyrB10 provide three potential H-bond donors in the distal cavity capable of stabilizing the incoming ligands. The role of these residues in key topological positions, and their interplay with the iron-bound ligands, has been addressed in studies carried out on the CO, F(-), OH(-), CN(-), and HS(-) adducts formed with the wild-type protein and a combinatorial set of mutants, in which the distal polar residues, TrpG8, TyrCD1, and TyrB10, have been singly, doubly, or triply replaced by a Phe residue. In this context, such a complete analysis provides an excellent benchmark for the investigation of the relationship between protein structure and function, allowing one to translate physicochemical properties of the active site into the observed functional behaviour. Tf-trHb will be compared with other members of the group II trHbs and, more generally, with members of the other trHb subgroups. © 2015 Elsevier Ltd. All rights reserved.

  20. Model of Communication Strategy for Public Relations in Private University in Building the Relationship with the Media

    OpenAIRE

    Darmastuti, Rini; Sinatra Wijaya, Lina

    2009-01-01

    The success of Public Relations work in Private University depends on the public relations strategy in building the relationship with the media. For knowing how effective PR strategy is in building the relationship with the media, A research has been done with 10 respondents ( 10 Private Universities in Central Java ) by using descriptive qualitative approach and direct observation. There are two relationship models that have been found from this research, they are “ Imbalanced Commensalisms ...

  1. Structural properties of MHC class II ligands, implications for the prediction of MHC class II epitopes.

    Directory of Open Access Journals (Sweden)

    Kasper Winther Jørgensen

    2010-12-01

    Full Text Available Major Histocompatibility class II (MHC-II molecules sample peptides from the extracellular space allowing the immune system to detect the presence of foreign microbes from this compartment. Prediction of MHC class II ligands is complicated by the open binding cleft of the MHC class II molecule, allowing binding of peptides extending out of the binding groove. Furthermore, only a few HLA-DR alleles have been characterized with a sufficient number of peptides (100-200 peptides per allele to derive accurate description of their binding motif. Little work has been performed characterizing structural properties of MHC class II ligands. Here, we perform one such large-scale analysis. A large set of SYFPEITHI MHC class II ligands covering more than 20 different HLA-DR molecules was analyzed in terms of their secondary structure and surface exposure characteristics in the context of the native structure of the corresponding source protein. We demonstrated that MHC class II ligands are significantly more exposed and have significantly more coil content than other peptides in the same protein with similar predicted binding affinity. We next exploited this observation to derive an improved prediction method for MHC class II ligands by integrating prediction of MHC- peptide binding with prediction of surface exposure and protein secondary structure. This combined prediction method was shown to significantly outperform the state-of-the-art MHC class II peptide binding prediction method when used to identify MHC class II ligands. We also tried to integrate N- and O-glycosylation in our prediction methods but this additional information was found not to improve prediction performance. In summary, these findings strongly suggest that local structural properties influence antigen processing and/or the accessibility of peptides to the MHC class II molecule.

  2. The relationship between medicine, spirituality and religion: three models for integration.

    Science.gov (United States)

    Balboni, Michael J; Puchalski, Christina M; Peteet, John R

    2014-10-01

    The integration of medicine and religion is challenging for historical, ethical, practical and conceptual reasons. In order to make more explicit the bases and goals of relating spirituality and medicine, we distinguish here three complementary perspectives: a whole-person care model that emphasizes teamwork among generalists and spiritual professionals; an existential functioning view that identifies a role for the clinician in promoting full health, including spiritual well-being; and an open pluralism view, which highlights the importance of differing spiritual and cultural traditions in shaping the relationship.

  3. Torpedo formation and Purkinje cell loss: modeling their relationship in cerebellar disease.

    Science.gov (United States)

    Louis, Elan D; Kuo, Sheng-Han; Vonsattel, Jean-Paul G; Faust, Phyllis L

    2014-08-01

    Torpedo formation and Purkinje cell (PC) loss represent standard and inter-related cerebellar responses to injury. Surprisingly, the nature of their relationship has not been carefully characterized across a range of normal and disease states. Are brains with more torpedoes expected to have fewer PCs? We quantified torpedoes and PCs in four groups: essential tremor (ET), spinocerebellar ataxia (SCA), multiple system atrophy-cerebellar (MSA-C), and controls. Brains from 100 individuals (58 ET, 27 controls, 7 SCA, 8 MSA-C) were available at the New York Brain Bank. After complete neuropathological assessment, a standard parasagittal neocerebellar block was harvested; a 7-μm thick section was stained with Luxol fast blue/hematoxylin and eosin; and torpedoes and PCs were quantified. For a given PC count, SCA and MSA-C cases often had higher torpedo counts than ET cases or controls. Furthermore, the relationship between torpedo and PC counts was complex. The correlation between torpedo and PC counts was negative in ET cases (i.e., individuals with more torpedoes had fewer PCs [i.e., more PC loss]) whereas the relationship was positive in MSA-C cases (i.e., individuals with fewer PCs [i.e., more PC loss] had fewer torpedoes). Patients with SCA showed both patterns. When all diagnostic groups were combined, the correlation was best fit by a quadratic (i.e., parabolic) model rather than a simple linear model; this model incorporated data on the negative correlation in ET cases, the mixed results in SCA cases, and the positive correlation in MSA-C cases (r = 0.636). The relationship between torpedo and PC counts was complex and heterogeneous across a range of cerebellar disease states, and was best characterized by a quadratic rather than a simple model. With more severe cerebellar disease, torpedoes can be quite numerous and are likely a common feature of surviving PCs, but eventually, dramatic loss of PC leads to a paradoxical reduction in observable torpedoes.

  4. The Models of Relationship between Training and Psyche development in Cultural-historical and Activity Approaches

    Directory of Open Access Journals (Sweden)

    Pogozhina I.N.,

    2016-12-01

    Full Text Available The possibility of referring of the psychological theories studying interrelation of training and mental development processes to this or that stage of scientific knowledge formation on the basis of studied objects types and corresponded determination systems as a basic criterion distinguishing the ideals of scientific rationality is justified. General characteristics of classical, non-classical and post-non-classical models, determination of the mechanisms of dissipative systems, requirements for learning and development model building in the context of post-non-classic science paradigm on the criterion of the system features of the object of cognition are described. Domestic psychological school models are compared with associanism, behaviorism, gestalt psychology and Piaget determination models on the number of options allocated to these determinants, types of causal chains and types of links between causal chains. It is shown that cultural-historical approach is situated intermediately between post-non-classical and non-classical models, while activity approach corresponds to post-non-classical understanding of the object of study as complicated self-developing "man-size" system. Determination relationships models developed by L.V.Vygotskii, S.L. Rubinstein, A.N. Leont’ev continue to play the heuristic role at the present stage of scientific development.

  5. Seismic attenuation relationship with homogeneous and heterogeneous prediction-error variance models

    Science.gov (United States)

    Mu, He-Qing; Xu, Rong-Rong; Yuen, Ka-Veng

    2014-03-01

    Peak ground acceleration (PGA) estimation is an important task in earthquake engineering practice. One of the most well-known models is the Boore-Joyner-Fumal formula, which estimates the PGA using the moment magnitude, the site-to-fault distance and the site foundation properties. In the present study, the complexity for this formula and the homogeneity assumption for the prediction-error variance are investigated and an efficiency-robustness balanced formula is proposed. For this purpose, a reduced-order Monte Carlo simulation algorithm for Bayesian model class selection is presented to obtain the most suitable predictive formula and prediction-error model for the seismic attenuation relationship. In this approach, each model class (a predictive formula with a prediction-error model) is evaluated according to its plausibility given the data. The one with the highest plausibility is robust since it possesses the optimal balance between the data fitting capability and the sensitivity to noise. A database of strong ground motion records in the Tangshan region of China is obtained from the China Earthquake Data Center for the analysis. The optimal predictive formula is proposed based on this database. It is shown that the proposed formula with heterogeneous prediction-error variance is much simpler than the attenuation model suggested by Boore, Joyner and Fumal (1993).

  6. Relationships among sexual knowledge, sexual attitudes, and safe sex behaviour among adolescents: a structural equation model.

    Science.gov (United States)

    Lou, Jiunn-Horng; Chen, Sheng-Hwang

    2009-12-01

    The purpose of this cross-sectional study was to test a cause-and-effect model of factors affecting sexual health among Taiwanese adolescents. A structural equation model was proposed in which the relationships among sexual knowledge, sexual attitudes, and safe sex behaviour were explored. The study collected data from 823 adolescent students at a junior college in Central Taiwan. Participants were assessed using the Sexual Knowledge Scale, Sexual Attitudes Scale, and Safe Sex Behaviour Questionnaire and the demographic data were collected. The preliminary model fit criteria, overall model fit, and fit of internal structure of model was used to assess the sexual health model fit. Results revealed that sexual knowledge had a negative effect on sex attitudes and had no significant effect on safe sex behaviour. Adolescents with more sexual knowledge had less positive sexual attitudes and did not show increased practices of safe sex behaviour. No significant correlation was found between sexual knowledge and safe sex behaviour of adolescents. Improvements in sexual attitudes were found to be irrelevant to the promotion of safe sex behaviour of adolescents. In order to ensure safe sexual health, it is strongly suggested that adolescents learn to be responsible for their own behaviours and attitudes and obtain correct knowledge about their understandings and evaluations of sexuality.

  7. Different phylogenomic approaches to resolve the evolutionary relationships among model fish species.

    Science.gov (United States)

    Negrisolo, Enrico; Kuhl, Heiner; Forcato, Claudio; Vitulo, Nicola; Reinhardt, Richard; Patarnello, Tomaso; Bargelloni, Luca

    2010-12-01

    Comparative genomics holds the promise to magnify the information obtained from individual genome sequencing projects, revealing common features conserved across genomes and identifying lineage-specific characteristics. To implement such a comparative approach, a robust phylogenetic framework is required to accurately reconstruct evolution at the genome level. Among vertebrate taxa, teleosts represent the second best characterized group, with high-quality draft genome sequences for five model species (Danio rerio, Gasterosteus aculeatus, Oryzias latipes, Takifugu rubripes, and Tetraodon nigroviridis), and several others are in the finishing lane. However, the relationships among the acanthomorph teleost model fishes remain an unresolved taxonomic issue. Here, a genomic region spanning over 1.2 million base pairs was sequenced in the teleost fish Dicentrarchus labrax. Together with genomic data available for the above fish models, the new sequence was used to identify unique orthologous genomic regions shared across all target taxa. Different strategies were applied to produce robust multiple gene and genomic alignments spanning from 11,802 to 186,474 amino acid/nucleotide positions. Ten data sets were analyzed according to Bayesian inference, maximum likelihood, maximum parsimony, and neighbor joining methods. Extensive analyses were performed to explore the influence of several factors (e.g., alignment methodology, substitution model, data set partitions, and long-branch attraction) on the tree topology. Although a general consensus was observed for a closer relationship between G. aculeatus (Gasterosteidae) and Di. labrax (Moronidae) with the atherinomorph O. latipes (Beloniformes) sister taxon of this clade, with the tetraodontiform group Ta. rubripes and Te. nigroviridis (Tetraodontiformes) representing a more distantly related taxon among acanthomorph model fish species, conflicting results were obtained between data sets and methods, especially with respect

  8. Relationship between Anxiety and Burnout among Chinese Physicians: A Moderated Mediation Model.

    Directory of Open Access Journals (Sweden)

    Jiawei Zhou

    Full Text Available The main goal of this research was to investigate the complex relationships among coping styles, personality, burnout, and anxiety using a moderated mediation analysis.A random cluster sampling procedure was used to select a total of 1274 physicians from two tertiary grade A hospitals in Heilongjiang Province, which is located in northeast China. The Zung Self-Rating Anxiety Scale (SAS, Chinese Maslach Burnout Inventory (CMBI, Chinese version of the EPQ-revised Short Scale, and the Trait Coping Style Questionnaire (TCSQ were used to gather data. Moderated mediation analysis was used in this study; it was executed using the PROCESS macro so that the mediators and moderator could function together in the same model.The prevalence of anxiety symptoms among the physicians was 31%, and there were no differences between the sexes. The results showed that positive and negative coping styles partially mediated the association between burnout and anxiety symptoms in physicians. The mediated effect of positive coping styles was moderated by Eysenck's Psychoticism traits.Personality traits moderate the strength of the relationships between burnout and anxiety mediated by positive coping styles; however, personality traits do not moderate the strength of the relationships between burnout and anxiety mediated by negative coping styles.

  9. Relationship between Anxiety and Burnout among Chinese Physicians: A Moderated Mediation Model.

    Science.gov (United States)

    Zhou, Jiawei; Yang, Yanjie; Qiu, Xiaohui; Yang, Xiuxian; Pan, Hui; Ban, Bo; Qiao, Zhengxue; Wang, Lin; Wang, Wenbo

    2016-01-01

    The main goal of this research was to investigate the complex relationships among coping styles, personality, burnout, and anxiety using a moderated mediation analysis. A random cluster sampling procedure was used to select a total of 1274 physicians from two tertiary grade A hospitals in Heilongjiang Province, which is located in northeast China. The Zung Self-Rating Anxiety Scale (SAS), Chinese Maslach Burnout Inventory (CMBI), Chinese version of the EPQ-revised Short Scale, and the Trait Coping Style Questionnaire (TCSQ) were used to gather data. Moderated mediation analysis was used in this study; it was executed using the PROCESS macro so that the mediators and moderator could function together in the same model. The prevalence of anxiety symptoms among the physicians was 31%, and there were no differences between the sexes. The results showed that positive and negative coping styles partially mediated the association between burnout and anxiety symptoms in physicians. The mediated effect of positive coping styles was moderated by Eysenck's Psychoticism traits. Personality traits moderate the strength of the relationships between burnout and anxiety mediated by positive coping styles; however, personality traits do not moderate the strength of the relationships between burnout and anxiety mediated by negative coping styles.

  10. The Impact of Intimate Partner Violence on Decisions to Leave Dating Relationships: A Test of the Investment Model

    Science.gov (United States)

    Rhatigan, Deborah L.; Street, Amy E.

    2005-01-01

    This study explored the impact of violence exposure on investment-model constructs within a sample of college women involved in heterosexual dating relationships. Results generally supported the "common sense" hypothesis, suggesting that violence negatively impacts satisfaction for and commitment to one's relationship and is positively associated…

  11. A new structure-property connection in the skeletal elements of the marine sponge Tethya aurantia that guards against buckling instability

    Science.gov (United States)

    Monn, Michael A.; Kesari, Haneesh

    2017-01-01

    We identify a new structure-property connection in the skeletal elements of the marine sponge Tethya aurantia. The skeletal elements, known as spicules, are millimeter-long, axisymmetric, silica rods that are tapered along their lengths. Mechanical designs in other structural biomaterials, such as nacre and bone, have been studied primarily for their benefits to toughness properties. The structure-property connection we identify, however, falls in the entirely new category of buckling resistance. We use computational mechanics calculations and information about the spicules’ arrangement within the sponge to develop a structural mechanics model for the spicules. We use our structural mechanics model along with measurements of the spicules’ shape to estimate the load they can transmit before buckling. Compared to a cylinder with the same length and volume, we predict that the spicules’ shape enhances this critical load by up to 30%. We also find that the spicules’ shape is close to the shape of the column that is optimized to transmit the largest load before buckling. In man-made structures, many strategies are used to prevent buckling. We find, however, that the spicules use a completely new strategy. We hope our discussion will generate a greater appreciation for nature’s ability to produce beneficial designs.

  12. Constitutional Isomers of Dendrimer-like Star Polymers: Design, Synthesis and Conformational and Structural Properties

    Energy Technology Data Exchange (ETDEWEB)

    Pople, John A

    2001-03-22

    The design, synthesis and solution properties of six constitutional isomers of dendrimer-like star polymers is described. Each of the polymers have comparable molecular weights ({approx} 80,000 g/mol), narrow polydispersities (< 1.19) and an identical number of branching junctures (45) and surface hydroxyl functionalities (48). The only difference in the six isomers is the placement of the branching junctures. The polymers are constructed from high molecular weight poly(e-caprolactone) with branching junctures derived from 2,2'-bis(hydroxylmethyl) propionic acid (bis-MPA) emanating from a central core. The use of various generations of dendritic initiators and dendrons coupled with the ring opening polymerization of e-caprolactones allowed a modular approach to the dendrimer-like star polymer isomers. The most pronounced effects on the physical properties/morphology and hydrodynamic volume was for those polymers in which the branching was distributed throughout the sample in a dendrimer-like fashion. The versatility of this approach has provided the possibility of understanding the relationship between architecture and physical properties. Dynamic light scattering and small angle X-ray scattering techniques were used to determine the hydrodynamic radius Rh and radius of gyration Rg respectively. The relationship between Rg and molecular weight was indicative of a compact star-like structure, and did not show advanced bias towards either the dense core or dense shell models. The radial density distribution of the isomers was therefore modeled according to a many arm star polymer, and good agreement was found with experimental measures of Rh/Rg.

  13. ON THE INFLUENTIAL POINTS IN THE FUNCTIONAL CIRCULAR RELATIONSHIP MODELS WITH AN APPLICATION ON WIND DATA

    Directory of Open Access Journals (Sweden)

    ALi Hassan Abuzaid

    2013-12-01

    Full Text Available If the interest is to calibrate two instruments then the functional relationship model is more appropriate than regression models. Fitting a straight line when both variables are circular and subject to errors has not received much attention. In this paper, we consider the problem of detecting influential points in two functional relationship models for circular variables. The first is based on the simple circular regression the (SC, while the last is derived from the complex linear regression the (CL.   The covariance matrices are derived and then the COVRATIO statistics are formulated for both models. The cut-off points are obtained and the power of performance is assessed via simulation studies.   The performance of COVRATIO statistics depends on the concentration of error, sample size and level of contamination. In the case of linear relationship between two circular variables COVRATIO statistics of the (SC model performs better than the (CL.  On the other hand, a novel diagram, the so-called spoke plot, is utilized to detect possible influential points For illustration purposes, the proposed procedures are applied on real data of wind directions measured by two different instruments. COVRATIO statistics and the spoke plot were able to identify two observations as influential points. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"جدول عادي"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;}

  14. Adjustment problems and maladaptive relational style: a mediational model of sexual coercion in intimate relationships.

    Science.gov (United States)

    Salwen, Jessica K; O'Leary, K Daniel

    2013-07-01

    Four hundred and fifty-three married or cohabitating couples participated in the current study. A meditational model of men's perpetration of sexual coercion within an intimate relationship was examined based on past theories and known correlates of rape and sexual coercion. The latent constructs of adjustment problems and maladaptive relational style were examined. Adjustment problem variables included perceived stress, perceived low social support, and marital discord. Maladaptive relational style variables included psychological aggression, dominance, and jealousy. Sexual coercion was a combined measure of men's reported perpetration and women's reported victimization. As hypothesized, adjustment problems significantly predicted sexual coercion. Within the meditational model, adjustment problems were significantly correlated with maladaptive relational style, and maladaptive relational style significantly predicted sexual coercion. Once maladaptive relational style was introduced as a mediator, adjustment problems no longer significantly predicted sexual coercion. Implications for treatment, limitations, and future research are discussed.

  15. Developing an Innovative Customer Relationship Management Model for Better Health Examination Service

    Directory of Open Access Journals (Sweden)

    Lyu JrJung

    2014-11-01

    Full Text Available People emphasize on their own health and wish to know more about their conditions. Chronic diseases now take up to 50 percent of top 10 causes of death. As a result, the health-care industry has emerged and kept thriving. This work adopts an innovative customer-oriented business model since most clients are proactive and spontaneous in taking the “distinguished” health examination programs. We adopt the soft system dynamics methodology (SSDM to develop and to evaluate the steps of introducing customer relationship management model into a case health examination organization. Quantitative results are also presented for a case physical examination center and to assess the improved efficiency. The case study shows that the procedures developed here could provide a better service.

  16. The Relationship Between Life Satisfaction and ADHD Symptoms in Middle School Students: Using a Bifactor Model.

    Science.gov (United States)

    Ogg, Julia A; Bateman, Lisa; Dedrick, Robert F; Suldo, Shannon M

    2016-05-01

    ADHD is associated with increased academic and social difficulties and comorbid psychopathology which may lead to decreased life satisfaction (LS). The current study utilized a bifactor model of ADHD consisting of a general factor and two specific factors (inattention and hyperactivity-impulsivity) to determine if ADHD symptoms place middle school students (n= 183) at risk for diminished LS and if this relationship differed depending on whether teachers versus students reported ADHD symptoms. Confirmatory factor analyses indicated that the bifactor model provided very good fit to the ADHD symptoms reported by students (comparative fit index [CFI] = .995; root mean square error of approximation [RMSEA] = .028) and teachers (CFI = .997; RMSEA = .043). Results also demonstrated that when students rated ADHD symptoms, the general ADHD factor and inattention were negatively related to LS; however, when teachers rated ADHD symptoms, only inattention was negatively related to LS. Implications and future directions related to these results are discussed. © The Author(s) 2014.

  17. A model of school problems, academic failure, alcohol initiation, and the relationship to adult heroin injection.

    Science.gov (United States)

    Trenz, Rebecca C; Harrell, Paul; Scherer, Michael; Mancha, Brent E; Latimer, William W

    2012-08-01

    The current study uses structural equation modeling to investigate factors associated with alcohol initiation and injection heroin use. Baseline data from the NEURO-HIV Epidemiologic Study in Baltimore, Maryland, were used. Participants were 404 injection heroin users (M(age) = 32.72) with a history of regular injection in their lifetime. Latent variables were created for self-reported school problems and academic failure. The final model indicated that greater school problems were associated with earlier alcohol initiation (ß = -0.22, p failure was directly related to greater frequency of recent heroin injection (ß = 0.15, p < .01). The results expand research investigating the relationship between adolescent behavior and illicit drug use in adulthood.

  18. Developing a Customer Relationship Management Model for Better Health Examination Service

    Directory of Open Access Journals (Sweden)

    Lyu Jr-Jung

    2014-11-01

    Full Text Available People emphasize on their own health and wish to know more about their conditions. Chronic diseases now take up to 50 percent of top 10 causes of death. As a result, the health-care industry has emerged and kept thriving. This work adopts a customer-oriented business model since most clients are proactive and spontaneous in taking the “distinguished” health examination programs. We adopt the soft system dynamics methodology (SSDM to develop and to evaluate the steps of introducing customer relationship management model into a case health examination organization. Quantitative results are also presented for a case physical examination center and to assess the improved efficiency. The case study shows that the procedures developed here could provide a better service.

  19. A Novel Numerical Approach for a Nonlinear Fractional Dynamical Model of Interpersonal and Romantic Relationships

    Directory of Open Access Journals (Sweden)

    Jagdev Singh

    2017-07-01

    Full Text Available In this paper, we propose a new numerical algorithm, namely q-homotopy analysis Sumudu transform method (q-HASTM, to obtain the approximate solution for the nonlinear fractional dynamical model of interpersonal and romantic relationships. The suggested algorithm examines the dynamics of love affairs between couples. The q-HASTM is a creative combination of Sumudu transform technique, q-homotopy analysis method and homotopy polynomials that makes the calculation very easy. To compare the results obtained by using q-HASTM, we solve the same nonlinear problem by Adomian’s decomposition method (ADM. The convergence of the q-HASTM series solution for the model is adapted and controlled by auxiliary parameter ℏ and asymptotic parameter n. The numerical results are demonstrated graphically and in tabular form. The result obtained by employing the proposed scheme reveals that the approach is very accurate, effective, flexible, simple to apply and computationally very nice.

  20. The Analysis And Design Of Customer Relationship Management Model At STMIK STIKOM BALI

    Directory of Open Access Journals (Sweden)

    Ni Wayan Deriani

    2016-06-01

    Full Text Available The advantages of an organization can be seen from the organization's ability to compete in the business world today is increasingly more competition. The competition should be used as well as possible in order to retain customers by providing the best service. one way to provide the best service is the provision of means in the form of comprehensive information systems and integrated. CRM is an integrated system that is useful for both of the organization and of course for the customer. In this research, design analysis model of CRM approach from the perspective Planner and owner of Zachman framework. Design analysis using DFD, ERD and conceptual database. The expected outcome of this research is a form of planning the Customer Relationship Management system model as a reference for the managers in the development of an integrated system in the future.

  1. In-silico prediction of sweetness using structure-activity relationship models.

    Science.gov (United States)

    Goel, Anukrati; Gajula, Kishore; Gupta, Rakesh; Rai, Beena

    2018-07-01

    Quantitative structure activity relationship (QSAR) models appear to be an ideal tool for quick screening of promising candidates from a vast library of molecules, which can then be further designed, synthesized and tested using a combination of rigorous first principle simulations, such as molecular docking, molecular dynamics simulation and experiments. In this study, QSAR models have been built with an extensive dataset of 487 compounds to predict the sweetness potency relative to sucrose (ranging 0.2-220,000). The whole dataset was randomly split into training and test sets in a 70:30 ratio. The models were developed using Genetic Function Approximation (R test 2  = 0.832) and Artificial Neural Network (R test 2  = 0.831). Our models thus offer a convenient route for fast screening of molecules prior to synthesis and testing. Additionally, this study can supplement a molecular modelling approach to improve binding of molecules with sweet taste receptors, leading to design of novel sweeteners. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Modelling price and volatility inter-relationships in the Australian wholesale spot electricity markets

    International Nuclear Information System (INIS)

    Higgs, Helen

    2009-01-01

    This paper examines the inter-relationships of wholesale spot electricity prices among the four regional electricity markets in the Australian National Electricity Market (NEM): namely, New South Wales, Queensland, South Australia and Victoria using the constant conditional correlation and Tse and Tsui's (Tse, Y.K., Tsui, A.K.C., 2002. A multivariate generalised autoregressive conditional heteroscedasticity model with time-varying correlations. Journal of Business and Economic Statistics 20 (3), 351-362.) and Engle's (Engle, R., 2002. Dynamic conditional correlation: a sample class of multivariate generalized autoregressive conditional heteroskedasticity models. Journal of Business and Economic Statistics 20 (3), 339-350.) dynamic conditional correlation multivariate GARCH models. Tse and Tsui's (Tse, Y.K., Tsui, A.K.C., 2002. A multivariate generalised autoregressive conditional heteroscedasticity model with time-varying correlations. Journal of Business and Economic Statistics 20 (3), 351-362.) dynamic conditional correlation multivariate GARCH model which takes account of the Student t specification produces the best results. At the univariate GARCH(1,1) level, the mean equations indicate the presence of positive own mean spillovers in all four markets and little evidence of mean spillovers from the other lagged markets. In the dynamic conditional correlation equation, the highest conditional correlations are evident between the well-connected markets indicating the presence of strong interdependence between these markets with weaker interdependence between the not so well-interconnected markets. (author)

  3. Modeling Relationships between Shrubland Biomass and Pattern Water Use Efficiency Along Semi-Arid Climatic Gradients

    Science.gov (United States)

    Shoshany, Maxim

    2014-05-01

    A new model is presented that represents the effect of the shrub patches' spatial arrangement on their water use efficiency and biomass productivity in water limited ecosystems. The model utilizes an Edge Ratio parameterization calculated as the ratio between vegetation edge area and the total vegetation area. Pattern Water Use Efficiency employs the following relationships: 1. Water Use efficiency would be directly related to shrub Cover Fraction. 2. Water Use Efficiency would be Inversely related to amount of edge areas (Edge Ratio). 3. The effect of Edge would be Inversely related to shrub cover fraction. 4. The effect of Edge would be Inversely related to the shrubs' height. Pattern Water Use Efficiency than modulates the use of precipitation in producing biomass. Preliminary assessment of the new model was achieved by comparing its results with biomass as extracted from high-resolution imagery based on allometric equations for 18 sites along a climatic gradient between Mediterranean and arid regions in Central Israel. In the next phase, the model is modified to allow its implementation with Landsat Imagery. This form of the model facilitated wide regional mapping of shrublands' biomass. Such mapping is fundamental for assessing the impacts of climate change on ecosystems productivity in desert fringe ecosystems.

  4. Antiproliferative Pt(IV) complexes: synthesis, biological activity, and quantitative structure-activity relationship modeling.

    Science.gov (United States)

    Gramatica, Paola; Papa, Ester; Luini, Mara; Monti, Elena; Gariboldi, Marzia B; Ravera, Mauro; Gabano, Elisabetta; Gaviglio, Luca; Osella, Domenico

    2010-09-01

    Several Pt(IV) complexes of the general formula [Pt(L)2(L')2(L'')2] [axial ligands L are Cl-, RCOO-, or OH-; equatorial ligands L' are two am(m)ine or one diamine; and equatorial ligands L'' are Cl- or glycolato] were rationally designed and synthesized in the attempt to develop a predictive quantitative structure-activity relationship (QSAR) model. Numerous theoretical molecular descriptors were used alongside physicochemical data (i.e., reduction peak potential, Ep, and partition coefficient, log Po/w) to obtain a validated QSAR between in vitro cytotoxicity (half maximal inhibitory concentrations, IC50, on A2780 ovarian and HCT116 colon carcinoma cell lines) and some features of Pt(IV) complexes. In the resulting best models, a lipophilic descriptor (log Po/w or the number of secondary sp3 carbon atoms) plus an electronic descriptor (Ep, the number of oxygen atoms, or the topological polar surface area expressed as the N,O polar contribution) is necessary for modeling, supporting the general finding that the biological behavior of Pt(IV) complexes can be rationalized on the basis of their cellular uptake, the Pt(IV)-->Pt(II) reduction, and the structure of the corresponding Pt(II) metabolites. Novel compounds were synthesized on the basis of their predicted cytotoxicity in the preliminary QSAR model, and were experimentally tested. A final QSAR model, based solely on theoretical molecular descriptors to ensure its general applicability, is proposed.

  5. Artificial neural network models of relationships between Alternaria spores and meteorological factors in Szczecin (Poland)

    Science.gov (United States)

    Grinn-Gofroń, Agnieszka; Strzelczak, Agnieszka

    2008-11-01

    Alternaria is an airborne fungal spore type known to trigger respiratory allergy symptoms in sensitive patients. Aiming to reduce the risk for allergic individuals, we constructed predictive models for the fungal spore circulation in Szczecin, Poland. Monthly forecasting models were developed for the airborne spore concentrations of Alternaria, which is one of the most abundant fungal taxa in the area. Aerobiological sampling was conducted over 2004-2007, using a Lanzoni trap. Simultaneously, the following meteorological parameters were recorded: daily level of precipitation; maximum and average wind speed; relative humidity; and maximum, minimum, average, and dew point temperature. The original factors as well as with lags (up to 3 days) were used as the explaining variables. Due to non-linearity and non-normality of the data set, the modelling technique applied was the artificial neural network (ANN) method. The final model was a split model with classification (spore presence or absence) followed by regression for spore seasons and log(x+1) transformed Alternaria spore concentration. All variables except maximum wind speed and precipitation were important factors in the overall classification model. In the regression model for spore seasons, close relationships were noted between Alternaria spore concentration and average and maximum temperature (on the same day and 3 days previously), humidity (with lag 1) and maximum wind speed 2 days previously. The most important variable was humidity recorded on the same day. Our study illustrates a novel approach to modelling of time series with short spore seasons, and indicates that the ANN method provides the possibility of forecasting Alternaria spore concentration with high accuracy.

  6. A Two-Factor Autoregressive Moving Average Model Based on Fuzzy Fluctuation Logical Relationships

    Directory of Open Access Journals (Sweden)

    Shuang Guan

    2017-10-01

    Full Text Available Many of the existing autoregressive moving average (ARMA forecast models are based on one main factor. In this paper, we proposed a new two-factor first-order ARMA forecast model based on fuzzy fluctuation logical relationships of both a main factor and a secondary factor of a historical training time series. Firstly, we generated a fluctuation time series (FTS for two factors by calculating the difference of each data point with its previous day, then finding the absolute means of the two FTSs. We then constructed a fuzzy fluctuation time series (FFTS according to the defined linguistic sets. The next step was establishing fuzzy fluctuation logical relation groups (FFLRGs for a two-factor first-order autoregressive (AR(1 model and forecasting the training data with the AR(1 model. Then we built FFLRGs for a two-factor first-order autoregressive moving average (ARMA(1,m model. Lastly, we forecasted test data with the ARMA(1,m model. To illustrate the performance of our model, we used real Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX and Dow Jones datasets as a secondary factor to forecast TAIEX. The experiment results indicate that the proposed two-factor fluctuation ARMA method outperformed the one-factor method based on real historic data. The secondary factor may have some effects on the main factor and thereby impact the forecasting results. Using fuzzified fluctuations rather than fuzzified real data could avoid the influence of extreme values in historic data, which performs negatively while forecasting. To verify the accuracy and effectiveness of the model, we also employed our method to forecast the Shanghai Stock Exchange Composite Index (SHSECI from 2001 to 2015 and the international gold price from 2000 to 2010.

  7. The Relationship between Ethical Culture and Unethical Behavior in Work Groups: Testing the Corporate Ethical Virtues Model

    NARCIS (Netherlands)

    S.P. Kaptein (Muel)

    2008-01-01

    textabstractThe Corporate Ethical Virtues Model, which is a model for measuring the ethical culture of organizations, has not been tested on its predictive validity. This study tests the relationship between this model and observed unethical behavior in work groups. The sample consists of 301 triads

  8. Modeling Relationships among 217 Fires Using Remote Sensing of Burn Severity in Southern Pine Forests

    Directory of Open Access Journals (Sweden)

    Amr Abd-Elrahman

    2011-09-01

    Full Text Available Pine flatwoods forests in the southeastern US have experienced severe wildfires over the past few decades, often attributed to fuel load build-up. These forest communities are fire dependent and require regular burning for ecosystem maintenance and health. Although prescribed fire has been used to reduce wildfire risk and maintain ecosystem integrity, managers are still working to reintroduce fire to long unburned areas. Common perception holds that reintroduction of fire in long unburned forests will produce severe fire effects, resulting in a reluctance to prescribe fire without first using expensive mechanical fuels reduction techniques. To inform prioritization and timing of future fire use, we apply remote sensing analysis to examine the set of conditions most likely to result in high burn severity effects, in relation to vegetation, years since the previous fire, and historical fire frequency. We analyze Landsat imagery-based differenced Normalized Burn Ratios (dNBR to model the relationships between previous and future burn severity to better predict areas of potential high severity. Our results show that remote sensing techniques are useful for modeling the relationship between elevated risk of high burn severity and the amount of time between fires, the type of fire (wildfire or prescribed burn, and the historical frequency of fires in pine flatwoods forests.

  9. Team Investment and Longitudinal Relationships: An Innovative Global Health Education Model.

    Science.gov (United States)

    Myers, Kimberly R; Fredrick, N Benjamin

    2017-12-01

    Increasing student interest in global health has resulted in medical schools offering more global health opportunities. However, concerns have been raised, particularly about one-time, short-term experiences, including lack of follow-through for students and perpetuation of unintentional messages of global health heroism, neocolonialism, and disregard for existing systems and communities of care. Medical schools must develop global health programs that address these issues. The Global Health Scholars Program (GHSP) was created in 2008-2009 at Penn State College of Medicine. This four-year program is based on values of team investment and longitudinal relationships and uses the service-learning framework of preparation, service, and reflection. Teams of approximately five students, with faculty oversight, participate in two separate monthlong trips abroad to the same host community in years 1 and 4, and in campus- and Web-based activities in years 2 and 3. As of December 2016, 191 students have been accepted into the GHSP. Since inception, applications have grown by 475% and program sites have expanded from one to seven sites on four continents. The response from students has been positive, but logistical challenges persist in sustaining team investment and maintaining longitudinal relationships between student teams and host communities. Formal methods of assessment should be used to compare the GHSP model with more traditional approaches to global health education. Other medical schools with similar aims can adapt the GHSP model to expand their global health programming.

  10. Models of Workplace Incivility: The Relationships to Instigated Incivility and Negative Outcomes

    Directory of Open Access Journals (Sweden)

    Kristoffer Holm

    2015-01-01

    Full Text Available The aim of the study was to investigate workplace incivility as a social process, examining its components and relationships to both instigated incivility and negative outcomes in the form of well-being, job satisfaction, turnover intentions, and sleeping problems. The different components of incivility that were examined were experienced and witnessed incivility from coworkers as well as supervisors. In addition, the organizational factors, social support, control, and job demands, were included in the models. A total of 2871 (2058 women and 813 men employees who were connected to the Swedish Hotel and Restaurant Workers Union completed an online questionnaire. Overall, the results from structural equation modelling indicate that whereas instigated incivility to a large extent was explained by witnessing coworker incivility, negative outcomes were to a high degree explained by experienced supervisor incivility via mediation through perceived low social support, low control, and high job demands. Unexpectedly, the relationships between incivility (experienced coworker and supervisor incivility, as well as witnessed supervisor incivility and instigated incivility were moderated by perceived high control and high social support. The results highlight the importance of including different components of workplace incivility and organizational factors in future studies of the area.

  11. Relationship between Family Adaptability, Cohesion and Adolescent Problem Behaviors: Curvilinearity of Circumplex Model.

    Science.gov (United States)

    Joh, Ju Youn; Kim, Sun; Park, Jun Li; Kim, Yeon Pyo

    2013-05-01

    The Family Adaptability and Cohesion Evaluation Scale (FACES) III using the circumplex model has been widely used in investigating family function. However, the criticism of the curvilinear hypothesis of the circumplex model has always been from an empirical point of view. This study examined the relationship between adolescent adaptability, cohesion, and adolescent problem behaviors, and especially testing the consistency of the curvilinear hypotheses with FACES III. We used the data from 398 adolescent participants who were in middle school. A self-reported questionnaire was used to evaluate the FACES III and Youth Self Report. According to the level of family adaptability, significant differences were evident in internalizing problems (P = 0.014). But, in externalizing problems, the results were not significant (P = 0.305). Also, according to the level of family cohesion, significant differences were in internalizing problems (P = 0.002) and externalizing problems (P = 0.004). The relationship between the dimensions of adaptability, cohesion and adolescent problem behaviors was not curvilinear. In other words, adolescents with high adaptability and high cohesion showed low problem behaviors.

  12. Models of Workplace Incivility: The Relationships to Instigated Incivility and Negative Outcomes.

    Science.gov (United States)

    Holm, Kristoffer; Torkelson, Eva; Bäckström, Martin

    2015-01-01

    The aim of the study was to investigate workplace incivility as a social process, examining its components and relationships to both instigated incivility and negative outcomes in the form of well-being, job satisfaction, turnover intentions, and sleeping problems. The different components of incivility that were examined were experienced and witnessed incivility from coworkers as well as supervisors. In addition, the organizational factors, social support, control, and job demands, were included in the models. A total of 2871 (2058 women and 813 men) employees who were connected to the Swedish Hotel and Restaurant Workers Union completed an online questionnaire. Overall, the results from structural equation modelling indicate that whereas instigated incivility to a large extent was explained by witnessing coworker incivility, negative outcomes were to a high degree explained by experienced supervisor incivility via mediation through perceived low social support, low control, and high job demands. Unexpectedly, the relationships between incivility (experienced coworker and supervisor incivility, as well as witnessed supervisor incivility) and instigated incivility were moderated by perceived high control and high social support. The results highlight the importance of including different components of workplace incivility and organizational factors in future studies of the area.

  13. The Entropy Solutions for the Lighthill-Whitham-Richards Traffic Flow Model with a Discontinuous Flow-Density Relationship

    National Research Council Canada - National Science Library

    Lu, Yadong; Wong, S. C; Zhang, Mengping; Shu, Chi-Wang

    2007-01-01

    ...) traffic flow model with a flow-density relationship which is piecewise quadratic, concave, but not continuous at the junction points where two quadratic polynomials meet, and with piecewise linear...

  14. Using tensor product splines in modeling exposure–time–response relationships: Application to the Colorado Plateau Uranium Miners cohort

    OpenAIRE

    Berhane, Kiros; Hauptmann, Michael; Langholz, Bryan

    2008-01-01

    An adequate depiction of exposure–time–response relationships is important in assessing public health implications of an occupational or environmental exposure. Recent advances have focused on flexible modeling of the overall shape of latency. Methods are needed to allow for varying shapes of latency under different exposure profiles. A tensor product spline model is proposed for describing exposure–response relationships for protracted time-dependent occupational exposure histories in epidem...

  15. The practical use of resistance modelling to interpret the gas separation properties of hollow fiber membranes

    International Nuclear Information System (INIS)

    Ahmad Fauzi Ismail; Shilton, S.J.

    2000-01-01

    A simple resistance modelling methodology is presented for gas transport through asymmetric polymeric membranes. The methodology allows fine structural properties such as active layer thickness and surface porosity, to be determined from experimental gas permeation data. This paper, which could be regarded as a practical guide, shows that resistance modeling, if accompanied by realistic working assumptions, need not be difficult and can provide a valuable insight into the relationships between the membrane fabrication conditions and performance of gas separation membranes. (Author)

  16. Pharmacokinetic/Pharmacodynamic Relationship of Gabapentin in a CFA-induced Inflammatory Hyperalgesia Rat Model.

    Science.gov (United States)

    Larsen, Malte Selch; Keizer, Ron; Munro, Gordon; Mørk, Arne; Holm, René; Savic, Rada; Kreilgaard, Mads

    2016-05-01

    Gabapentin displays non-linear drug disposition, which complicates dosing for optimal therapeutic effect. Thus, the current study was performed to elucidate the pharmacokinetic/pharmacodynamic (PKPD) relationship of gabapentin's effect on mechanical hypersensitivity in a rat model of CFA-induced inflammatory hyperalgesia. A semi-mechanistic population-based PKPD model was developed using nonlinear mixed-effects modelling, based on gabapentin plasma and brain extracellular fluid (ECF) time-concentration data and measurements of CFA-evoked mechanical hyperalgesia following administration of a range of gabapentin doses (oral and intravenous). The plasma/brain ECF concentration-time profiles of gabapentin were adequately described with a two-compartment plasma model with saturable intestinal absorption rate (K m  = 44.1 mg/kg, V max  = 41.9 mg/h∙kg) and dose-dependent oral bioavailability linked to brain ECF concentration through a transit compartment. Brain ECF concentration was directly linked to a sigmoid E max function describing reversal of hyperalgesia (EC 50, plasma  = 16.7 μg/mL, EC 50, brain  = 3.3 μg/mL). The proposed semi-mechanistic population-based PKPD model provides further knowledge into the understanding of gabapentin's non-linear pharmacokinetics and the link between plasma/brain disposition and anti-hyperalgesic effects. The model suggests that intestinal absorption is the primary source of non-linearity and that the investigated rat model provides reasonable predictions of clinically effective plasma concentrations for gabapentin.

  17. EMD-regression for modelling multi-scale relationships, and application to weather-related cardiovascular mortality

    Science.gov (United States)

    Masselot, Pierre; Chebana, Fateh; Bélanger, Diane; St-Hilaire, André; Abdous, Belkacem; Gosselin, Pierre; Ouarda, Taha B. M. J.

    2018-01-01

    In a number of environmental studies, relationships between natural processes are often assessed through regression analyses, using time series data. Such data are often multi-scale and non-stationary, leading to a poor accuracy of the resulting regression models and therefore to results with moderate reliability. To deal with this issue, the present paper introduces the EMD-regression methodology consisting in applying the empirical mode decomposition (EMD) algorithm on data series and then using the resulting components in regression models. The proposed methodology presents a number of advantages. First, it accounts of the issues of non-stationarity associated to the data series. Second, this approach acts as a scan for the relationship between a response variable and the predictors at different time scales, providing new insights about this relationship. To illustrate the proposed methodology it is applied to study the relationship between weather and cardiovascular mortality in Montreal, Canada. The results shed new knowledge concerning the studied relationship. For instance, they show that the humidity can cause excess mortality at the monthly time scale, which is a scale not visible in classical models. A comparison is also conducted with state of the art methods which are the generalized additive models and distributed lag models, both widely used in weather-related health studies. The comparison shows that EMD-regression achieves better prediction performances and provides more details than classical models concerning the relationship.

  18. Investigation of structural properties, electrical and dielectrical characteristics of Al/Dy2O3/porous Si heterostructure

    Science.gov (United States)

    Cherif, A.; Jomni, S.; Belgacem, W.; Hannachi, R.; Mliki, N.; Beji, L.

    2014-04-01

    This paper describes the structural properties, electrical and dielectric characteristics for the first time of the high-k Dy2O3 oxide film deposited on the porous Si substrate by electron beam deposition under ultra vacuum. Structural and morphological characterizations are investigated by a scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction measurements (XRD). The electrical and dielectric characteristics of the Al/Dy2O3/porous Si heterostructure are studied through current- voltage I (V), capacitance-voltage C (V), conductance- and capacitance-frequency dependencies (G (f) and C (f)). Therefore, the dominant conduction mechanisms for the Al/Dy2O3/porous Si heterostructure are extracted from the determining of Schottky coefficient (βSC) and Poole-Frenkel coefficient (βPF). The experimental values of βSC and βPF coefficients are calculated from I (V) characteristics and compared with theoretical values, thus, the appropriate model has been proposed. The C (V) characteristics at different frequencies revealed a large frequency-dispersion, indicative of a significant density of interface states. Furthermore, the G (f) characteristics were well fitted by the modified law GAC(f)=A1f+A2f and the results showed frequency dependent and evidence of two different behaviors in ac conductance i.e. the low-frequency conductivity is due to long-range ordering (frequency-independent) and high frequency conduction due to the localized orientation hopping mechanism. The Nyquist diagrams are used to identify the equivalent circuit, so, the Al/Dy2O3/porous Si heterostructure is accurately modeled at frequency ranges from 10 Hz to 1000 kHz, as a two parallel elements (RC) network placed in series.

  19. Deconstructing Constructivism: Modeling Causal Relationships Among Constructivist Learning Environment Factors and Student Outcomes in Introductory Chemistry

    Science.gov (United States)

    Komperda, Regis

    The purpose of this dissertation is to test a model of relationships among factors characterizing aspects of a student-centered constructivist learning environment and student outcomes of satisfaction and academic achievement in introductory undergraduate chemistry courses. Constructivism was chosen as the theoretical foundation for this research because of its widespread use in chemical education research and practice. In a constructivist learning environment the role of the teacher shifts from delivering content towards facilitating active student engagement in activities that encourage individual knowledge construction through discussion and application of content. Constructivist approaches to teaching introductory chemistry courses have been adopted by some instructors as a way to improve student outcomes, but little research has been done on the causal relationships among particular aspects of the learning environment and student outcomes. This makes it difficult for classroom teachers to know which aspects of a constructivist teaching approach are critical to adopt and which may be modified to better suit a particular learning environment while still improving student outcomes. To investigate a model of these relationships, a survey designed to measure student perceptions of three factors characterizing a constructivist learning environment in online courses was adapted for use in face-to-face chemistry courses. These three factors, teaching presence, social presence, and cognitive presence, were measured using a slightly modified version of the Community of Inquiry (CoI) instrument. The student outcomes investigated in this research were satisfaction and academic achievement, as measured by standardized American Chemical Society (ACS) exam scores and course grades. Structural equation modeling (SEM) was used to statistically model relationships among the three presence factors and student outcome variables for 391 students enrolled in six sections of a

  20. Quantitative structure-activity relationship models of chemical transformations from matched pairs analyses.

    Science.gov (United States)

    Beck, Jeremy M; Springer, Clayton

    2014-04-28

    The concepts of activity cliffs and matched molecular pairs (MMP) are recent paradigms for analysis of data sets to identify structural changes that may be used to modify the potency of lead molecules in drug discovery projects. Analysis of MMPs was recently demonstrated as a feasible technique for quantitative structure-activity relationship (QSAR) modeling of prospective compounds. Although within a small data set, the lack of matched pairs, and the lack of knowledge about specific chemical transformations limit prospective applications. Here we present an alternative technique that determines pairwise descriptors for each matched pair and then uses a QSAR model to estimate the activity change associated with a chemical transformation. The descriptors effectively group similar transformations and incorporate information about the transformation and its local environment. Use of a transformation QSAR model allows one to estimate the activity change for novel transformations and therefore returns predictions for a larger fraction of test set compounds. Application of the proposed methodology to four public data sets results in increased model performance over a benchmark random forest and direct application of chemical transformations using QSAR-by-matched molecular pairs analysis (QSAR-by-MMPA).