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Sample records for structure properties relationships

  1. 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 of the cured material even though density values of cured and postcured PMR were essentially the same. Preliminary results of a continuous and intermittent stress relaxation experiment for BMI:MDA in a 2:1 molar ratio indicate that crosslinking is occurring when the sample is in the undeformed state. Computer simulation of properties such as density, glass transition temperature, and modulus for the low-temperature cure conditions of BMI/MDA and BMI/DABA were completed. The computer modeling was used to help further understand and confirm the structure characterization results. The simulations correctly predicted the trends of these properties versus mole fraction BMI and were extended to other BMI/diamine systems.

  2. Microstructure mechanical properties relationship in bainitic structures

    International Nuclear Information System (INIS)

    In the present work, the microstructures and their mechanical properties have been studies in different bainitic structures. therefore, different bainitic morphologies have been produced by isothermal treatments carried out at different temperatures. For these steels, 400-450 degree centigree is the optimum range of temperatures in order to obtain bainitic structures. If the Temperature is higher, perlite is also formed and if it is lower, martensite is obtained during quenching. SEM and EBSD/OIM techniques were applied in order to study the microstructure. Tensile tests were carried out for mechanical characterization. (Author) 20 refs

  3. 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 reduce the O2 flux of FEP films infused with Palladium (Pd) nano-particles, up to two hundred fold decrease. In contrast, H2 has essentially no effect on the transport of CO2. The generality of the remarkable reduction in oxygen flux was also demonstrated with films of PP, LLDPE, PET, Nylon 6,6 infused with Pd nano-particles. This oxygen scavenging effect became more pronounced at lower oxygen concentrations. The catalytic role of Pd in the reaction of O2 and H2, and the enormous surface area provided by the dispersed nano-particles were responsible for this highly efficient oxygen scavenging effect. (Abstract shortened by UMI.)

  4. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, M.

    2012-01-01

    The complicated structural speciation in boroaluminosilicate glasses leads to a mixed network former effect yielding nonlinear variation in many macroscopic properties as a function of chemical composition. Here we study the composition–structure–property relationships in a series of sodium 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.

  5. 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.

  6. Structure-Property Relationship of Perfluorinated Sulfonic Acid (PFSA) Membranes

    Science.gov (United States)

    Kusoglu, Ahmet; Weber, Adam

    2013-03-01

    Perfluorosulfonic-acid (PFSA) membrane is the most commonly used ionomer in electrochemical energy storage and conversion devices thanks to its remarkable proton conductivity, perm-selectivity, wide electrochemical window, and mechanical stability. Most of these properties are the result of the membrane's phase-separated nanostructure where ions and solvents transport through the hydrated domains while the surrounding hydrophobic PTFE backbone acts as a mechanical support. Thus, it is essential to understand the solvent- and humidity-induced morphological changes and their associated impact on the membrane's properties for optimizing the structure-property relationship desired by the electrochemical devices. In this talk, correlations among the mechanical (e.g., modulus), electrochemical (e.g., ionic conductivity) and nanostructural (e.g., domain spacing) properties during hydration is discussed. Moreover, the impact of thermal history, mechanical reinforcement, and side-chain length on the structure-property correlation is examined. Even though the properties vary for the membranes investigated, similar correlations are found between the degree of hydration, domain spacing, and ionic conductivity.

  7. GH11 xylanases: Structure/function/properties relationships and applications.

    Science.gov (United States)

    Paës, Gabriel; Berrin, Jean-Guy; Beaugrand, Johnny

    2012-01-01

    For technical, environmental and economical reasons, industrial demands for process-fitted enzymes have evolved drastically in the last decade. Therefore, continuous efforts are made in order to get insights into enzyme structure/function relationships to create improved biocatalysts. Xylanases are hemicellulolytic enzymes, which are responsible for the degradation of the heteroxylans constituting the lignocellulosic plant cell wall. Due to their variety, xylanases have been classified in glycoside hydrolase families GH5, GH8, GH10, GH11, GH30 and GH43 in the CAZy database. In this review, we focus on GH11 family, which is one of the best characterized GH families with bacterial and fungal members considered as true xylanases compared to the other families because of their high substrate specificity. Based on an exhaustive analysis of the sequences and 3D structures available so far, in relation with biochemical properties, we assess biochemical aspects of GH11 xylanases: structure, catalytic machinery, focus on their "thumb" loop of major importance in catalytic efficiency and substrate selectivity, inhibition, stability to pH and temperature. GH11 xylanases have for a long time been used as biotechnological tools in various industrial applications and represent in addition promising candidates for future other uses. PMID:22067746

  8. Structure-property relationships in polymers for dielectric capacitors

    Science.gov (United States)

    Gupta, Sahil

    Effective energy storage is a key challenge of the 21st century that has fueled research in the area of energy storage devices. In this dissertation, structure-property relationships have been evaluated for polymers that might be suitable for storing energy in high-energy density, high-temperature capacitors. Firstly, hydroxyl-modified polypropylenes (PPOH) were synthesized by copolymerization of the propylene and undecenyloxytrimethylsilane monomers. The presence of H-bonding in PPOH copolymers increased their glass-transition temperature. Steric hindrance by the comonomer reduced the PP crystal growth rate and crystal size, resulting in a melting point depression. The comonomer was restricted outside the crystalline domains leaving the alpha-monoclinic crystal structure of PP unaffected, but increasing the fold-surface free energy. Crystallization was slower for PPOH copolymers than PP, but exhibited a skewed bell curve as a function of hydroxyl concentration. H-bonding persisted even at melt temperatures up to 250°C resulting in a higher elasticity and viscosity for PPOH copolymers. Secondly, sulfonated poly(ether ether ketone) (HSPEEK) was synthesized by sulfonating PEEK with sulfuric acid, and further neutralized with Zn to obtain ZnSPEEK. The thermal and dielectric properties of SPEEK were compared with PEEK. The glass-transition increased and melting point were high enough to enable the use of polymer at 180°C. The incorporation of sulfonic groups in PEEK increased the dielectric constant. HSPEEK had a higher dielectric constant than ZnSPEEK due to higher dipolar mobility, but the dielectric loss was also higher for HSPEEK due to electrode polarization and DC conduction. These results were consistent with our observations from sulfonated polystyrene (HSPS), which was used as a >model&lang' polymer. Lastly, commercial poly(4-methyl-1-pentene) (P4MP) was characterized to check its viability as a high-temperature polymer dielectric. Thermal stability up to 200°C, high melting point (> 225°C) and melting onset at 160 - 190°C indicated that P4MP could be used at 180 - 200°C. Thin free-standing films (~10 mum) with controlled crystal structure and surface morphology were prepared using blade coating and their drying dynamics were measured using a custom-designed solvent-casting platform. These films were further stretched uniaxially or biaxially, and their effect on the dielectric properties of P4MP was studied.

  9. Relationships between structure and mechanical properties of Inconel 718

    International Nuclear Information System (INIS)

    Ageing of Inconel 718 is studied. Life and tensile properties after ageing are practically independent of the quench structure. Simple ageing provides the material with a range of high properties and often makes a second ageing treatment unnecessary for the parts prior to working close to room temperature

  10. Transport properties of ribbon-shaped carbon fibers: Property-structure relationship

    Science.gov (United States)

    Gallego, Nidia Constanza

    Mesophase pitch-based carbon fibers are an ideal material for applications in which high rates of heat dissipation and low mass are required. Unfortunately, the high cost of current commercial high thermal conductivity mesophase pitch-based carbon fibers has limited their use in high volume applications. Understanding how the structure develops during the fiber formation process and how this structure relates to the final fiber properties is the way to optimizing the fiber properties while reducing the processing costs. Ribbon-shaped fibers have been developed at Clemson University and are being evaluated as a low-cost high thermal conductivity alternative fiber to traditional round-shaped fibers. However, the characterization of the thermal transport properties of carbon fibers is a difficult and time-consuming process. The objectives of this study were to evaluate the transport (both thermal and electronic) properties of ribbon-shaped fibers produced from an AR mesophase at different processing conditions, to characterize the structure of these fibers, to study their structure-property relationships, and to develop a model capable of estimating the thermal conductivity of carbon fibers based upon their structural parameters. For this purpose, several sets of ribbon fibers were produced from an AR mesophase at different spinning temperatures and shear rates and heat treated at a final temperature of 2400°C. The electrical resistivities, magnetoresistances and thermal conductivities of these fibers were measured and the structural parameters were determined with x-ray techniques. Two approaches (a short-fiber composite, and a periodic composite) were utilized to model the relationship between the structure of the fiber and its thermal conductivity. The results of this study confirmed that ribbon-shaped fibers develop excellent transport properties at lower graphitization temperatures than those used commercially for round-shaped fibers. Additionally, for the first time, two models that directly relate the structure of the carbon fiber to its thermal conductivity were developed.

  11. Structure-property relationships for methyl-terminated alkyl self-assembled monolayers

    Science.gov (United States)

    DelRio, Frank W.; Rampulla, David M.; Jaye, Cherno; Stan, Gheorghe; Gates, Richard S.; Fischer, Daniel A.; Cook, Robert F.

    2011-08-01

    Structure-property relationships for methyl-terminated alkyl self-assembled monolayers (SAMs) are developed using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and atomic force microscopy (AFM). NEXAFS C K-edge spectra are used to compute the dichroic ratio, which provides a quantitative measure of the molecular structure. AFM data are analyzed with an elastic adhesive contact model, modified by a first-order elastic perturbation method to include substrate effects, to extract the monolayer mechanical properties. Using this approach, the measured mechanical properties are not influenced by the substrate, which allows universal structure-property relationships to be developed for methyl-terminated alkyl SAMs.

  12. Structure-property relationships and biocompatibility of carbohydrate crosslinked polyurethanes.

    Science.gov (United States)

    Solanki, Archana; Mehta, Jayen; Thakore, Sonal

    2014-09-22

    Biocompatible and biodegradable polyurethanes (PUs) based on castor oil and polypropylene glycols (PPGs) were prepared using various carbohydrate crosslinkers: monosaccharide (glucose), disaccharide (sucrose) and polysaccharides (starch and cellulose). The mechanical and thermal properties were investigated and interpreted on the basis of SEM study. The advantage of incorporating various carbohydrates is to have tunable mechanical properties and biodegradability due to variety in their structure. The glass transition temperature and sorption behavior were dominated by the type of polyol than by the type of crosslinker. All the PUs were observed to be biodegradable as well as non-cytotoxic as revealed by MTT assay in normal lung cell line L132. The study supports the suitability of carbohydrates as important components of biocompatible PUs for development of biomedical devices. PMID:24906764

  13. Prediction of Environmental Properties for Chlorophenols with Posetic Quantitative Super-Structure/Property Relationships (QSSPR

    Directory of Open Access Journals (Sweden)

    Douglas J. Kleinc

    2006-09-01

    Full Text Available Due to their widespread use in bactericides, insecticides, herbicides, andfungicides, chlorophenols represent an important source of soil contaminants. Theenvironmental fate of these chemicals depends on their physico-chemical properties. In theabsence of experimental values for these physico-chemical properties, one can use predictedvalues computed with quantitative structure-property relationships (QSPR. As analternative to correlations to molecular structure we have studied the super-structure of areaction network, thereby developing three new QSSPR models (poset-average, cluster-expansion, and splinoid poset that can be applied to chemical compounds which can behierarchically ordered into a reaction network. In the present work we illustrate these posetQSSPR models for the correlation of the octanol/water partition coefficient (log Kow and thesoil sorption coefficient (log KOC of chlorophenols. Excellent results are obtained for allQSSPR poset models to yield: log Kow, r = 0.991, s = 0.107, with the cluster-expansionQSSPR; and log KOC, r = 0.938, s = 0.259, with the spline QSSPR. Thus, the poset QSSPRmodels predict environmentally important properties of chlorophenols.

  14. Quantitative Structure–Property Relationships for Aryldiazonia

    Directory of Open Access Journals (Sweden)

    Oxana I. Zhelezko

    2002-07-01

    Full Text Available Abstract: By the fact of finding 43 relationships, we have shown that the reduction potentials, dimerization potentials and potentials in half-equivalent point on titration of aryldiazonium cations XC6H4N+≡N (chemical reduction with K4[Fe(CN6] and TiCl3 in water, (C2H53N, (í-C4H94N+−OH, CH3OK and C10H8•−Na+ in acetone; polarographic reduction in nitromethane, sulfolane, and N,N-dimethylformamide are related linearly to the quantum chemically evaluated electron affinities (A and to the stabilization energies of radicals formed on diazonium cations reduction. Sixty six linear correlations of frequencies (ν characterizing a collection of bonds stretching vibrations of the C-N+≡N fragment in the XC6H4N+≡NY− salts with different anions in vaseline oil, N,N-dimethylformamide, acetone, ethylacetate, methanol, water, with the bonds orders of N≡N and C-N, with the charges on carbon atoms in para positions of the C6H5X molecules aromatic rings, with the mesomeric dipole moments (μm of X substituents have been found. Twelve quantitative relationships combining the μm and ν quantities with the A values have been established. The interrelations obtained have an explicitly expressed physical meaning, are featured by rather high correlation coefficients and have a predictive power in respect to redox properties, electron affinities, vibrational frequencies of aryldiazonia, as well as to mesomeric dipole moments of atomic groups in organic molecules.

  15. Structure-Property Relationships of Architectural Coatings by Neutron Methods

    Science.gov (United States)

    Nakatani, Alan

    2015-03-01

    Architectural coatings formulations are multi-component mixtures containing latex polymer binder, pigment, rheology modifiers, surfactants, and colorants. In order to achieve the desired flow properties for these formulations, measures of the underlying structure of the components as a function of shear rate and the impact of formulation variables on the structure is necessary. We have conducted detailed measurements to understand the evolution under shear of local microstructure and larger scale mesostructure in model architectural coatings formulations by small angle neutron scattering (SANS) and ultra small angle neutron scattering (USANS), respectively. The SANS results show an adsorbed layer of rheology modifier molecules exist on the surface of the latex particles. However, the additional hydrodynamic volume occupied by the adsorbed surface layer is insufficient to account for the observed viscosity by standard hard sphere suspension models (Krieger-Dougherty). The USANS results show the presence of latex aggregates, which are fractal in nature. These fractal aggregates are the primary structures responsible for coatings formulation viscosity. Based on these results, a new model for the viscosity of coatings formulations has been developed, which is capable of reproducing the observed viscosity behavior.

  16. Development of Computational Tools for Use in Quantitative Structure-Activity and Structure-Property Relationships

    Science.gov (United States)

    Dixon, Steven L.

    Computational tools are developed to relate theoretical aspects of molecular structure to experimental chemical behavior. The assumption that a causal relationship exists between molecular structure and chemical behavior is the fundamental premise that underlies the fields of quantitative structure-activity relationships (QSAR) and quantitative structure-property relationships (QSPR). Generation of a QSAR or QSPR involves the characterization of chemical structure in terms of numerical indices, and the development of mathematical models that correlate these indices with biological activities or physicochemical properties. Tools are developed in this thesis for use at three important stages of this process. A fast quantum mechanical molecular modeling technique based on a modified extended Huckel approach is developed for placing molecules in realistic energy-minimized conformations. The extended Huckel neglect-of-differential-overlap (EHNDO) method utilizes a one-electron approximation, semiempirical parameterization, and an efficient BFGS geometry optimization. The calculated molecular geometries from EHNDO are as accurate as those produced by the two-electron AM1 method, and the EHNDO geometry optimization is approximately three times faster. A new empirical method for calculating atomic charges is developed to characterize electronic structure. These charges are used in combination with the concepts of induction and resonance to arrive at an empirical model for pK _ a estimation in organic acids and bases. The PKACHG method generates partial atomic charges that yield accurate predictions of electric dipole moment, and the pK_ a model is accurate over wide ranges of acidity and basicity. Finally, nonlinear mathematical modeling techniques are investigated as a means of generating QSARs and QSPRs that contain stronger connections between calculated structure and experimental chemical behavior. A computational neural network program, QNET, is developed and outfitted with an efficient BFGS optimization for network training. A quadratic fitting routine, QUADFIT, is proposed as a fast alternative to neural networks. Both QNET and QUADFIT utilize external cross-validation during model development to prevent experimental data from being overfit. In a QSAR study of amine toxicity, QNET significantly outperforms conventional linear regression, and both QNET and QUADFIT yield post-model predictions that are considerably more accurate than those of linear regression.

  17. Neural networks as a method for elucidating structure-property relationships for organic compounds

    International Nuclear Information System (INIS)

    The published data devoted to the use of the neural network approach in the simulation of structure-property relationships for organic compounds are reviewed. The basic principles of the neural network simulation are discussed along with the characteristic features of the neural network approach typical of the representation and classification of structural chemical data. Brief information on neural network models of spectral characteristics, reactivities, physicochemical properties and biological activities of organic compounds is presented.

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

    OpenAIRE

    Schwab, J. J.; Malatesta, V.; La Mantia, F. P.; Tz Dintcheva, N.; Morici, E.; Arrigo, R.

    2012-01-01

    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....

  19. Structure-property-function relationships in triple helical collagen hydrogels

    CERN Document Server

    Tronci, Giuseppe; Russell, Stephen J; Wood, David J

    2012-01-01

    In order to establish defined biomimetic systems, type I collagen was functionalised with 1,3-Phenylenediacetic acid (Ph) as aromatic, bifunctional segment. Following investigation on molecular organization and macroscopic properties, material functionalities, i.e. degradability and bioactivity, were addressed, aiming at elucidating the potential of this collagen system as mineralization template. Functionalised collagen hydrogels demonstrated a preserved triple helix conformation. Decreased swelling ratio and increased thermo-mechanical properties were observed in comparison to state-of-the-art carbodiimide (EDC)-crosslinked collagen controls. Ph-crosslinked samples displayed no optical damage and only a slight mass decrease (~ 4 wt.-%) following 1-week incubation in simulated body fluid (SBF), while nearly 50 wt.-% degradation was observed in EDC-crosslinked collagen. SEM/EDS revealed amorphous mineral deposition, whereby increased calcium phosphate ratio was suggested in hydrogels with increased Ph content...

  20. 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.

  1. Structure-morphology-property relationships in polymerized ionic liquids

    Science.gov (United States)

    Sangoro, Joshua; Heres, Maximilian; Minutolo, Joseph; Shamblin, Jacob; Lang, Maik; Berdzinski, Stefan; Strehmel, Veronika; Paddison, Stephen

    2015-03-01

    Charge transport and structural dynamics in systematic series of polymerized ammonium- and imidazolium- based ionic liquids are investigated by broadband dielectric spectroscopy, temperature-modulated differential scanning calorimetry, and x-ray as well neutron scattering techniques. Detailed analysis reveal strong decoupling of these processes in the polymerized ionic liquids, implying failure of the classical theories in describing charge transport and molecular dynamics in these systems. In addition, a strong correlation is observed between the ionic conductivity at the respective calorimetric glass transition temperatures and the morphologies revealed by the scattering experiments. In this talk, a physical explanation of the origin of the observed decoupling of ionic conductivity from structural dynamics will be proposed.

  2. 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.

  3. Derivatives of Ergot-alkaloids: Molecular structure, physical properties, and structure-activity relationships

    Science.gov (United States)

    Ivanova, Bojidarka B.; Spiteller, Michael

    2012-09-01

    A comprehensive screening of fifteen functionalized Ergot-alkaloids, containing bulk aliphatic cyclic substituents at D-ring of the ergoline molecular skeleton was performed, studying their structure-active relationships and model interactions with ?2A-adreno-, serotonin (5HT2A) and dopamine D3 (D3A) receptors. The accounted high affinity to the receptors binding loops and unusual bonding situations, joined with the molecular flexibility of the substituents and the presence of proton accepting/donating functional groups in the studied alkaloids, may contribute to further understanding the mechanisms of biological activity in vivo and in predicting their therapeutic potential in central nervous system (CNS), including those related the Schizophrenia. Since the presented correlation between the molecular structure and properties, was based on the comprehensively theoretical computational and experimental physical study on the successfully isolated derivatives, through using routine synthetic pathways in a relatively high yields, marked these derivatives as 'treasure' for further experimental and theoretical studied in areas such as: (a) pharmacological and clinical testing; (b) molecular-drugs design of novel psychoactive substances; (c) development of the analytical protocols for determination of Ergot-alkaloids through a functionalization of the ergoline-skeleton, and more.

  4. Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR

    Energy Technology Data Exchange (ETDEWEB)

    Chinn, S C; Gjersing, E L; Maxwell, R S; Eastwood, E; Bowen, D; Stephens, T

    2006-07-14

    It is generally accepted that the properties of polymeric materials are controlled by the network structure and the reactions by which they have been constructed. These properties include the bulk moduli at creation, but also the properties as a function of age during use. In order to interpret mechanical properties and predict the time dependent changes in these properties, detailed knowledge of the effect of structural changes must be obtained. The degree and type of crosslinking, the molecular weight between crosslinks, the number of elastically ineffective chains (loops, dangling chain ends, sol-fraction) must be characterized. A number of theoretical and experimental efforts have been reported in the last few years on model networks prepared by endlinking reactions and the relationships of those structures with the ultimate mechanical properties. A range of experimental methods have been used to investigate structure including rheometric, scattering, infrared, {sup 29}Si MAS and CPMAS, {sup 1}H relaxation measurements, and recently {sup 1}H multiple quantum methods. Characterization of the growth of multiple quantum coherences have recently been shown to provide detailed insight into silicone network structure by the ability to selective probe the individual components of the polymer network, such as the polymer-filler interface or network chains. We have employed recently developed MQ methods to investigate the structure-property relationships in a series of complex, endlinked filled-PDMS blends. Here, a systematic study of the relationship between the molecular formulation, as dictated by the amount and type of crosslinks present and by the remaining network chains, and the segmental dynamics as observed by MQ NMR was performed.

  5. Rare-Earth Transition-Metal Intermetallics: Structure-bonding-Property Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Mi-Kyung Han

    2006-05-01

    Our explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding-property relationships. Our work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides RE{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  6. Rare-earth transition-metal intermetallics: Structure-bonding-property relationships

    Energy Technology Data Exchange (ETDEWEB)

    Han, M.K.

    2006-05-06

    The explorations of rare-earth, transition metal intermetallics have resulted in the synthesis and characterization, and electronic structure investigation, as well as understanding the structure-bonding property relationships. The work has presented the following results: (1) Understanding the relationship between compositions and properties in LaFe{sub 13-x}Si{sub x} system: A detailed structural and theoretical investigation provided the understanding of the role of a third element on stabilizing the structure and controlling the transformation of cubic NaZn{sub 13}-type structures to the tetragonal derivative, as well as the relationship between the structures and properties. (2) Synthesis of new ternary rare-earth iron silicides Re{sub 2-x}Fe{sub 4}Si{sub 14-y} and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi{sub 2}: This shows that the metal-semiconductor phase transition depends on the structure. The mechanism of band gap opening is described in terms of bonding and structural distortion. This result shows that the electronic structure calculations are an essential tool for understanding the relationship between structure and chemical bonding in these compounds. (4) Synthesis of new ternary rare-earth Zinc aluminides Tb{sub 3}Zn{sub 3.6}Al{sub 7.4}: Partially ordered structure of Tb{sub 3}Zn{sub 3.6}Al{sub 7.4} compound provides new insights into the formation, composition and structure of rare-earth transition-metal intermetallics. Electronic structure calculations attribute the observed composition to optimizing metal-metal bonding in the electronegative (Zn, Al) framework, while the specific ordering is strongly influenced by specific orbital interactions. (5) Synthesis of new structure type of Zn{sub 39}(Cr{sub x}Al{sub 1-x}){sub 81}: These layered structures are similar to icosahedral Mn-Al quasicrystalline compounds. Therefore, this compound may provide new insights into the formation, composition and structure of quasicrystalline materials.

  7. Some reflections on relationships between structure, properties, and performance of engineering materials

    International Nuclear Information System (INIS)

    The main object of materials science and technology is relationships between structure and properties. The practical use of engineering materials also involves consideration of things other than current theories for such relationships. Uncertainties of various kinds prompt reflections on the validity and applications of common practice based on experience. Among other things, this is true for decisions relating to reliability and safety. Hence, fundamental issues like determinism vs. probabilistics may become interesting to anyone who wants to deal efficiently with problems related to the use and performance of engineering materials

  8. Quantitative structure-property relationship modeling of Grätzel solar cell dyes.

    Science.gov (United States)

    Venkatraman, Vishwesh; Åstrand, Per-Olof; Alsberg, Bjørn Kåre

    2014-01-30

    With fossil fuel reserves on the decline, there is increasing focus on the design and development of low-cost organic photovoltaic devices, in particular, dye-sensitized solar cells (DSSCs). The power conversion efficiency (PCE) of a DSSC is heavily influenced by the chemical structure of the dye. However, as far as we know, no predictive quantitative structure-property relationship models for DSSCs with PCE as one of the response variables have been reported. Thus, we report for the first time the successful application of comparative molecular field analysis (CoMFA) and vibrational frequency-based eigenvalue (EVA) descriptors to model molecular structure-photovoltaic performance relationships for a set of 40 coumarin derivatives. The results show that the models obtained provide statistically robust predictions of important photovoltaic parameters such as PCE, the open-circuit voltage (V(OC)), short-circuit current (J(SC)) and the peak absorption wavelength ?(max). Some of our findings based on the analysis of the models are in accordance with those reported in the literature. These structure-property relationships can be applied to the rational structural design and evaluation of new photovoltaic materials. PMID:24222335

  9. Quantitative Structure-Property Relationships for the Normal Boiling Temperatures of Acyclic Carbonyl Compounds

    OpenAIRE

    Ovidiu Ivanciuc; Teodora Ivanciuc; Balaban, Alexandru T.

    2002-01-01

    Quantitative structure-property relationships (QSPR) models for the estimation of normal boiling temperatures for a set of 200 acyclic carbonyl compounds (containing mono- and dialdehydes, mono- and diketones, keto aldehydes, and esters of monocarboxylic acids) were established with the CODESSA program. The QSPR models developed with CODESSA allow accurate computation of the boiling temperatures of organic compounds using simple constitutional, topological, electrostatic and quantum indices t...

  10. Results from the Use of Molecular Descriptors Family on Structure Property/Activity Relationships

    Directory of Open Access Journals (Sweden)

    Sorana-Daniela Bolboacă

    2007-03-01

    Full Text Available The aim of the paper is to present the results obtained by utilization of an originalapproach called Molecular Descriptors Family on Structure-Property (MDF-SPR andStructure-Activity Relationships (MDF-SAR applied on classes of chemical compoundsand its usefulness as precursors of models elaboration of new compounds with betterproperties and/or activities and low production costs. The MDF-SPR/MDF-SARmethodology integrates the complex information obtained from compound’s structure inunitary efficient models in order to explain properties/activities. The methodology has beenapplied on a number of thirty sets of chemical compounds. The best subsets of moleculardescriptors family members able to estimate and predict property/activity of interest wereidentified and were statistically and visually analyzed. The MDF-SPR/MDF-SAR modelswere validated through internal and/or external validation methods. The estimation andprediction abilities of the MDF-SPR/MDF-SAR models were compared with previousreported models by applying of correlated correlation analysis, which revealed that theMDF-SPR/MDF-SAR methodology is reliable. The MDF-SPR/MDF-SAR methodologyopens a new pathway in understanding the relationships between compound’s structure andproperty/activity, in property/activity prediction, and in discovery, investigation andcharacterization of new chemical compounds, more competitive as costs andproperty/activity, being a method less expensive comparative with experimental methods.

  11. Relationship between structure and functional properties of normal rice starches with different amylose contents.

    Science.gov (United States)

    Cai, Jinwen; Man, Jianmin; Huang, Jun; Liu, Qiaoquan; Wei, Wenxian; Wei, Cunxu

    2015-07-10

    The structures (morphology, molecule, and crystallinity) and functional properties (gelatinization, hydrolysis, and in vitro digestion) of normal rice starches with different amylose contents were investigated and their relationships were analyzed. The results showed that the morphology, granule size, and crystalline type did not significantly change among rice starches. The molecular structure (amylose content, amylopectin branch-chain content, and amylopectin branching degree) and crystalline structure (relative crystallinity, IR ratio of 1045/1022cm(-1), lamellar peak intensity, and lamellar distance) significantly varied among rice starches, which resulted in different functional properties. The gelatinization temperature and water solubility were significantly positively correlated with amylose content but significantly negatively correlated with amylopectin short branch-chain. The swelling power, hydrolysis and in vitro digestion were significantly positively correlated with amylopectin short branch-chain, relative crystallinity, IR ratio of 1045/1022cm(-1), and lamellar peak intensity but significantly negatively correlated with amylose content and lamellar distance. PMID:25857957

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

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, Marcel

    Boroaluminosilicate glasses are important materials for various applications, e.g., liquid crystal display substrates, glass fibers for reinforcement, and thermal shock-resistant glass containers. The complicated structural speciation in these glasses leads to a mixed network former effect yielding nonlinear variation in many macroscopic properties. It is therefore crucial to investigate and understand structure-property correlations in boroaluminosilicate glasses. Here we study the structure-property relationships of a range of sodium boroaluminosilicate glasses from peralkaline to peraluminous 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 the effect of iron on the measured properties by doping these glasses with ~1 mol% of iron oxide.

  13. Polydopamine and eumelanin: from structure-property relationships to a unified tailoring strategy.

    Science.gov (United States)

    d'Ischia, Marco; Napolitano, Alessandra; Ball, Vincent; Chen, Chun-Teh; Buehler, Markus J

    2014-12-16

    CONSPECTUS: Polydopamine (PDA), a black insoluble biopolymer produced by autoxidation of the catecholamine neurotransmitter dopamine (DA), and synthetic eumelanin polymers modeled to the black functional pigments of human skin, hair, and eyes have burst into the scene of materials science as versatile bioinspired functional systems for a very broad range of applications. PDA is characterized by extraordinary adhesion properties providing efficient and universal surface coating for diverse settings that include drug delivery, microfluidic systems, and water-treatment devices. Synthetic eumelanins from dopa or 5,6-dihydroxyindoles are the focus of increasing interest as UV-absorbing agents, antioxidants, free radical scavengers, and water-dependent hybrid electronic-ionic semiconductors. Because of their peculiar physicochemical properties, eumelanins and PDA hold considerable promise in nanomedicine and bioelectronics, as they are biocompatible, biodegradable, and exhibit suitable mechanical properties for integration with biological tissues. Despite considerable similarities, very few attempts have so far been made to provide an integrated unifying perspective of these two fields of technology-oriented chemical research, and progress toward application has been based more on empirical approaches than on a solid conceptual framework of structure-property relationships. The present Account is an attempt to fill this gap. Following a vis-à-vis of PDA and eumelanin chemistries, it provides an overall view of the various levels of chemical disorder in both systems and draws simple correlations with physicochemical properties based on experimental and computational approaches. The potential of large-scale simulations to capture the macroproperties of eumelanin-like materials and their hierarchical structures, to predict the physicochemical properties of new melanin-inspired materials, to understand the structure-property-function relationships of these materials from the bottom up, and to design and optimize materials to achieve desired properties is illustrated. The impact of synthetic conditions on melanin structure and physicochemical properties is systematically discussed for the first time. Rational tailoring strategies directed to critical control points of the synthetic pathways, such as dopaquinone, DAquinone, and dopachrome, are then proposed, with a view to translating basic chemical knowledge into practical guidelines for material manipulation and tailoring. This key concept is exemplified by the recent demonstration that varying DA concentration, or using Tris instead of phosphate as the buffer, results in PDA materials with quite different structural properties. Realizing that PDA and synthetic eumelanins belong to the same family of functional materials may foster unprecedented synergisms between research fields that have so far been apart in the pursuit of tailorable and marketable materials for energy, biomedical, and environmental applications. PMID:25340503

  14. Processing-structure-property relationships in ultrafine grain and nanocrystalline materials

    International Nuclear Information System (INIS)

    This paper will review selected aspects of the processing-structure-property relationships in ultrafine grained (ufg- grain sizes 100 to 500 nm) and nanocrystalline (nc- grain sizes < 100 nm) materials. Of the various processing methods to obtain fine grain size materials, the two that have provided bulk artifactfree samples are electrodeposition and severe plastic deformation. The processing methods and important variables will be described for these techniques. Since the stability of the nanocrystalline microstructure is important for both processing (e.g. consolidation of powders) and elevated temperature mechanical property studies, the stability of nanocrystalline grain sizes as influenced by solute additions will be discussed. While hardness and strength usually increase with decreasing grain size, ductility is typically poor. There are now, however, a number of examples of nanocrystalline materials which combine high strength with good ductility. An example from the author's laboratory on nanocrystalline Cu with optimized mechanical properties will be presented.

  15. Structure–property relationships and residual stress quantification of a friction stir spot welded magnesium alloy

    International Nuclear Information System (INIS)

    Structure–property relationships and spatial residual stress distribution in a friction stir spot welded magnesium alloy (AZ31) sheet was investigated to elucidate the incipient deformation mechanisms and welding process parameters. Experimental results revealed a decrease in the tensile and compressive yield strengths, as well as an increase in ductility and grain size, as the tool rotational speed and shoulder depth increased. Residual stresses were measured using neutron diffraction, and a strong dependency was found between the grain size, residual stress and the welding parameters.

  16. Dissolution of SO3 within a lithium phosphate glass network and structure–property relationships

    OpenAIRE

    He?mono, Nicola?s; Mun?oz, Francisco

    2010-01-01

    The relationship between the structure and properties of glasses with composition 50Li2O.xSO3.(50?x)P2O5 (x=10–30, mol%) has been studied. SO3 can be dissolved into lithium phosphate glasses up to at least 20 mol%, while for glasses containing as much as 30 mol% SO3 it is present as crystalline Li2SO4, as seen by XRD and TEM. 31P NMR experiments have shown no bonds of the type P–O–S, thus it is thought that Li2SO4 can be homogeneously dissolved within the lithium phosphate...

  17. Synthesis and Quantitative Structure-Property Relationships of Side Chain-Modified Hyodeoxycholic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Antimo Gioiello

    2013-08-01

    Full Text Available Bile acids have emerged as versatile signalling compounds of a complex network of nuclear and membrane receptors regulating various endocrine and paracrine functions. The elucidation of the interconnection between the biological pathways under the bile acid control and manifestations of hepatic and metabolic diseases have extended the scope of this class of steroids for in vivo investigations. In this framework, the design and synthesis of novel biliary derivatives able to modulate a specific receptor requires a deep understanding of both structure-activity and structure-property relationships of bile acids. In this paper, we report the preparation and the critical micellization concentration evaluation of a series of hyodeoxycholic acid derivatives characterized by a diverse side chain length and by the presence of a methyl group at the alpha position with respect to the terminal carboxylic acid moiety. The data collected are instrumental to extend on a quantitative basis, the knowledge of the current structure-property relationships of bile acids and will be fruitful, in combination with models of receptor activity, to design and prioritize the synthesis of novel pharmacokinetically suitable ligands useful in the validation of bile acid-responsive receptors as therapeutic targets.

  18. 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.

  19. Key factors limiting carbon nanotube yarn strength: exploring processing-structure-property relationships.

    Science.gov (United States)

    Beese, Allison M; Wei, Xiaoding; Sarkar, Sourangsu; Ramachandramoorthy, Rajaprakash; Roenbeck, Michael R; Moravsky, Alexander; Ford, Matthew; Yavari, Fazel; Keane, Denis T; Loutfy, Raouf O; Nguyen, SonBinh T; Espinosa, Horacio D

    2014-11-25

    Studies of carbon nanotube (CNT) based composites have been unable to translate the extraordinary load-bearing capabilities of individual CNTs to macroscale composites such as yarns. A key challenge lies in the lack of understanding of how properties of filaments and interfaces across yarn hierarchical levels govern the properties of macroscale yarns. To provide insight required to enable the development of superior CNT yarns, we investigate the fabrication-structure-mechanical property relationships among CNT yarns prepared by different techniques and employ a Monte Carlo based model to predict upper bounds on their mechanical properties. We study the correlations between different levels of alignment and porosity and yarn strengths up to 2.4 GPa. The uniqueness of this experimentally informed modeling approach is the model's ability to predict when filament rupture or interface sliding dominates yarn failure based on constituent mechanical properties and structural organization observed experimentally. By capturing this transition and predicting the yarn strengths that could be obtained under ideal fabrication conditions, the model provides critical insights to guide future efforts to improve the mechanical performance of CNT yarn systems. This multifaceted study provides a new perspective on CNT yarn design that can serve as a foundation for the development of future composites that effectively exploit the superior mechanical performance of CNTs. PMID:25353651

  20. Comparative studies on rigid ? linker-based organic dyes: structure-property relationships and photovoltaic performance.

    Science.gov (United States)

    Li, Hairong; Koh, Teck Ming; Hao, Yan; Zhou, Feng; Abe, Yuichiro; Su, Haibin; Hagfeldt, Anders; Grimsdale, Andrew C

    2014-12-01

    A series of six structurally correlated donor-? bridge-acceptor organic dyes were designed, synthesized, and applied as sensitizers in dye-sensitized solar cells. Using the most widely studied donor (triarylamine) and cyclopenta[1,2-b:5,4-b']dithiophene or cyclopenta[1,2-b:5,4-b']dithiophene[2',1':4,5]thieno[2,3-d]thiophene as ? spacers, their structure-property relationships were investigated in depth by photophysical techniques and theoretical calculations. It was found that the photovoltaic performance of these dyes largely depends on their electronic structures, which requires synergistic interaction between donors and acceptors. Increasing the electron richness of the donor or the elongation of ?-conjugated bridges does not necessarily lead to higher performance. Rather, it is essential to rationally design the dyes by balancing their light-harvesting capability with achieving suitable energy levels to guarantee unimpeded charge separation and transport. PMID:25319943

  1. Synthetic Study on the Relationship Between Structure and Sweet Taste Properties of Steviol Glycosides

    Directory of Open Access Journals (Sweden)

    Grant Dubois

    2012-04-01

    Full Text Available The structure activity relationship between the C16-C17 methylene double bond on the aglycone of steviol glycosides and the corresponding impact on their sweet taste has been reported here for the first time. It has been observed that converting stevioside and rebaudioside A to their corresponding ketones by switching the doubly bonded methylene on C-17 for a ketone group actually removes the sweet taste properties of these molecules completely. Regenerating the original molecules tends to restore the sweet taste of both the steviol glycosides. Thus this C16-C17 methylene double bond in rebaudioside A and stevioside can be regarded as a pharmacophore essential for the sweetness property of these molecules.

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

    DEFF Research Database (Denmark)

    Zeng, Zhenhua; Kubal, Joseph

    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 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 step towards accurate identification and prediction of a variety of oxide/electrode interfacial structure-properties relationships, but also provides the foundation for rational design and control of ‘targeted active phases’ at catalytic interfaces. The successful design of bifunctional electrocatalysts that exploit these structures, in turn, could ultimately lead to advances in the development of alkaline fuel cells.

  3. An investigation of structure-property relationships in several categories of proton exchange membranes

    Science.gov (United States)

    Rodgers, Marianne Phelan

    The chemical and structural features of proton exchange membranes (PEMs) are related to their fuel cell relevant properties. The objective of this work is to understand structure-property relationships in PEMs through the fabrication and characterization of several classes of membranes. Incorporation of linear and angled monomers into the main chain of a polyimide permitted investigation of the effect of kinked versus linear polymers on membrane properties. The conductivity of angled sulfonated polyimide membranes is greater than those prepared from linear polymers, but water uptakes are lower. These differences are attributed to increased entanglements of angled polymers, which limit the degree of swelling and lead to increased proton concentration. Polyelectrolytes were incorporated into reinforcing materials to study the effect of incorporating and confining polyelectrolytes in the pores of reinforcing materials. The employment of reinforcing materials reduces conductivity, mobility, and permeance due to decreased ionomer content and connectivity of the ionomer. However, membranes are stronger and thinner, which compensates for these losses in terms of lower resistance and increased dimensional stability. Incorporating zirconium hydrogen phosphate (ZrP) and silicon dioxide (SiO2) into NafionRTM membranes permitted investigation of their effect on membrane properties. Data for NafionRTM/ZrP membranes support the theory that ZrP disrupts cohesive forces in Nafion RTM, causing it to absorb more water. The increased water content of the membranes does not result in increased conductivity because there is a concurrent decrease in proton concentration and mobility due to poorly conducting ZrP disrupting the conduction pathway and increased water content diluting protons and separating proton conduction sites. The decreasing density of the NafionRTM/SiO2 composite membranes with increasing SiO2 content and the increased dimensional stability of the membranes increasing compared to unmodified NafionRTM support the theory that a rigid scaffolding forms. Due to formation of void space that increases with increasing SiO2 content, water content increases, thus diluting the protons in the membrane, leading to lower conductivity. These structure-property relationships may be relevant to other membrane systems and should be considered when designing alternative systems for proton exchange membranes.

  4. Solvent effects on the structure-property relationship of anticonvulsant hydantoin derivatives: A solvatochromic analysis

    Directory of Open Access Journals (Sweden)

    Trišovi? Nemanja

    2011-10-01

    Full Text Available Abstract Considering the pharmaceutical importance of hydantoins, a set of 25 derivatives of phenytoin, nirvanol and 5-methyl-5-phenylhydantoin, the lipophilicities of which were gradually increased by the introduction of different alkyl, cycloalkyl and alkenyl groups in position N3, was synthesized. Their properties under consideration were either estimated empirically, by UV/Vis spectroscopy, or calculated using established medicinal chemistry software. The UV absorption spectra of the investigated compounds were recorded in the region from 200 to 400 nm, in selected solvents of different polarities. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen bonding interactions were analyzed by means of the linear solvation energy relationship (LSER concept proposed by Kamlet and Taft. Furthermore, the relationships between solvent-solute interactions and selected structural features of the solutes, which are believed to markedly affect the processes of absorption, distribution, metabolism, excretion and toxicity (ADMETox, were discussed. Satisfactory correlations were found between hydrogen bonding properties and solute size and the in silico calculated bioactivity descriptors, in particular %Abs. (human intestinal absorption, log BB (blood-brain barrier permeation and log kA (protein binding affinities parameters. In view of the results of this study, the investigated hydantoin derivatives met the pharmacokinetic criteria for pre-selection as drug candidates and qualified them for the pharmacodynamic phase of antiepileptic drug development.

  5. Quantitative structure—property relationship for thermal decomposition temperature of ionic liquids

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Sattari, Mehdi

    2012-01-01

    In this study, a wide literature survey has been conducted to gather an extensive set of thermal decomposition temperature (Td) data for ionic liquids (ILs). A data set consisting of Td data for 586 ILs was collated from 71 different literature sources. Using this data set, a reliable quantitative structure-property relationship has been developed. In order to consider the effects of the anion and cation on the Td of ILs, both anion-based and cation-based molecular descriptors were considered. Finally, a genetic function approximation method was used which selected 6 molecular descriptors for anions, and 6 molecular descriptors for cations to develop the model. The predictive capability of the 12-parameter model was evaluated using several validation techniques. Its applicability domain is discussed. The proposed model produces an acceptable average relative deviation of less than 5.2% taking into consideration all 586 experimental data values.

  6. Structure property relationship in aza-bodipy absorber materials for organic photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Gresser, Roland; Mueller, Toni; Hein, Moritz Philipp; Leo, Karl; Riede, Moritz [Institute of Applied Photophysics, Dresden University of Technology (Germany)

    2010-07-01

    In this joint experimental and theoretical study, we focus on the structure property relationship of aza-bodipy dyes as active donor materials in vacuum deposited small molecule solar cells. The position of the materials HOMO can be intentionally varied by the choice of the functional group attached to the molecule. The absorption spectra show a red shift of the maximum with increasing donor strength of the substituents due to the increasing HOMO energy and decreasing band gap. Based on crystal structure data, the charge carrier mobility determining parameters like reorganization energies and transfer integrals are calculated. The results show an increasing molecular orbital overlap and significant higher transfer integrals upon planarization and rigidification of the molecule. With this information, the observed charge carrier mobility differences from experiment can be explained. In addition to the electronic properties a high thermal and photo stability is essential. From combined thermogravimetric analysis and mass spectroscopy we could determine the degradation process of the material and were able to increase the thermal stability by substitution of the involved species.

  7. 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.

  8. Star-shaped molecules for organic photovoltaics: Synthesis and structure-property relationships

    Science.gov (United States)

    Bhandari, Yashpal

    In this thesis, the development and structure-property relationships of a novel class of two-dimensional star-shaped molecules synthesized for organic photovoltaics are presented. A promising approach towards low cost photovoltaics for power generation is fabrication of solar cells based on organic semiconductors. In addition to being a potentially reliable and environmentally friendly energy source, organic materials offer unique advantages such as low cost, lightweight, flexibility and high form factor. Though this field has witnessed tremendous progress over the last decade, power conversion efficiencies of the existing solar cells are still poor, prohibiting their wide spread commercial use. The available organic materials mainly suffer from low charge carrier mobilities and inefficient absorption in the bulk of the solar spectrum leading to low photocurrent generation. Charge transport in conjugated polymers is generally one-dimensional, while three-dimensional mobility is limited by the necessity for chain-to-chain activated hopping mechanism. Self-organization observed in conjugated crystalline small molecules and polymers favors strong intermolecular interactions in the pi-pi stacking distance and offers potential to improve charge carrier mobilities in organic materials. This motivated us to design and synthesize five different solution processible two-dimensional star-shaped molecules CN-X, THX-L, THX- S, THX-S=O and THX-D/A that offer interesting possibilities for improvement of charge mobilities and photophysical properties. The developed molecules self-organize in the form of pi-stacks and contain a tetra-substituted central phenyl ring with four phenylenevinylene or thiophene arms with conjugation through the arms and central phenyl core. The designed synthetic route is versatile, which enables facile incorporation of different electron rich and deficient moieties and solubilizing groups, thus facilitating systematic engineering of material properties like energy levels, bandgap, charge transport and solubility. The two-dimensional structural architecture with different functional groups led to molecules with small optical bandgaps in the range of 1.8-2.2 eV, absorbing in the bulk of the solar spectrum with band edges extending up to 700 nm and exhibiting strong intermolecular interactions in the pi-pi stacking distance of 3.5 A. A representative molecule, THX- L, from a set of four different oligothiophenes has shown field effect mobility of as high as 0.02 cm2V-1s-1 , which is amongst the best mobilities reported thus far for solution processible organics. In this thesis, the designed synthetic strategy, the fundamental structure-property relationships that govern the performance of the star molecules and their potential application mainly in solar cells and to some extent in light emitting diodes and field-effect transistors will be discussed. One relationship we have also investigated is whether the star architecture offers any fundamental advantages over linear molecules by comparing the properties of CN-X with its linear analog CN-L, which will be presented in the thesis.

  9. Structure–property relationships of oligothiophene–isoindigo polymers for efficient bulk-heterojunction solar cells

    DEFF Research Database (Denmark)

    Ma, Zaifei; Sun, Wenjun

    2014-01-01

    A series of alternating oligothiophene (nT)–isoindigo (I) copolymers (PnTI) were synthesized to investigate the influence of the oligothiophene block length on the photovoltaic (PV) properties of PnTI:PCBM bulk-heterojunction blends. Our study indicates that the number of thiophene rings (n) in the repeating unit alters both polymer crystallinity and polymer–fullerene interfacial energetics, which results in a decreasing open-circuit voltage (Voc) of the solar cells with increasing n. The short-circuit current density (Jsc) of P1TI:PCBM devices is limited by the absence of a significant driving force for electron transfer. Instead, blends based on P5TI and P6TI feature large polymer domains, which limit charge generation and thus Jsc. The best PV performance with a power conversion efficiency of up to 6.9% was achieved with devices based on P3TI, where a combination of a favorable morphology and an optimal interfacial energy level offset ensures efficient exciton separation and charge generation. The structure–property relationship demonstrated in this work would be a valuable guideline for the design of high performance polymers with small energy losses during the charge generation process, allowing for the fabrication of efficient solar cells that combine a minimal loss in Voc with a high Jsc.

  10. Thermal properties and nanodispersion behavior of synthesized ?-sitosteryl acyl esters : A structure-activity relationship study

    DEFF Research Database (Denmark)

    Panpipat, Worawan; Dong, Mingdong

    2013-01-01

    The efficiency (dose response) of cholesterol-lowering effect of phytosterols in humans depends on their chemical forms (derived or non-derived) and formulation methods in a delivery system. With a series of synthesized ?-sitosteryl fatty acid esters (C2:0-C18:0 and C18:1-C18:3), this work examined their thermal properties and applications in preparation of nanodispersion with ?-sitosterol as a comparison. Inspection of the melting point (Tm) and the heat of fusion (?H) of ?-sitosteryl fatty acid esters and the chain length and unsaturation degree of fatty acyl moiety revealed a pronounced structure-property relationship. The nanodispersions prepared with ?-sitosterol and ?-sitosteryl saturated fatty acid (SFA) esters displayed different particle size distribution patterns (polymodal vs bimodal), mean diameter (115nm vs less than 100nm), and polydispersity index (PDI) (0.50 vs 0.23-0.38). ?-sitosteryl unsaturated fatty acid (USFA) esters showed a distinctly different dispersion behavior to form nanoemulsions,rather than nanodispersions, with more homogeneous particle size distribution (monomodal, mean diameter 27-63nm and PDI 0.18-0.25). The nanodispersion of ?-sitosteryl medium chain SFA ester (C14:0) demonstrated a best storage stability.

  11. Processing, structure and property relationships in commercial thermotropic liquid crystalline polymers

    Science.gov (United States)

    Rendon, Stanley

    Thermotropic liquid crystalline polymers (TLCPs) offer considerable promise as high strength/lightweight engineering materials. Their excellent mechanical properties are derived from the spontaneous ordering of stiff polymer molecules in the melt state, which is ultimately translated into high molecular orientation in finished products. Understanding the effect of processing on molecular orientation, and specifically the role and mechanisms by which flow fields impact molecular orientation, is thus a prerequisite to rational design of processes that exploit and enhance the characteristics of TLCPs. The lack of fundamental knowledge to rationally anticipate structure development during processing of commercial main-chain TLCPs however, has significantly hindered the wide spread applicability of these materials. In light of the need for improved understanding of flow-orientation relationships in TLCPs, this thesis presents the first coordinated attempt to combine fundamental studies of orientation development in well-defined simple flows (simple shear) and complex processing flows (extrusion and injection molding) using in situ x-ray scattering methods, with structure and property investigations of injection molded plaques made from commercial TLCPs. The work described here addresses fundamental questions related to the shear-alignment behavior of several commercial (Vectra A950RTM, Vectra B950RTM) and pre-commercial (DHalphaMS) thermotropes. The use of well-established in situ x-ray scattering methods previously developed in the Burghardt group, has enabled us to probe the evolution of molecular orientation under the influence of various transient shear flow protocols some of which provide strong, indirect evidence of flow-tumbling behavior in Vectra copolyesters. In situ orientation studies in steady isothermal complex channel flows reveal that superposition of extensional gradients on the inhomogeneous shear of pressure-driven slit flows dramatically influences the degree, quality and character of the LCP molecular alignment. Coordinated efforts to study LCP orientation in injection molded plaques confirm that the types of orientation states that emerge in steady channel flows are also found in moldings, and that trends in orientation state with changes in mold geometry may be readily rationalized using the kinematic concepts developed through channel flow studies. Mechanical property characterization on tensile specimens cut from injection molded plaques reveal that properties such as strength and stiffness obey a universal correlation with ex situ x-ray measurements of molecular orientation. In situ, real-time studies of structure development during injection molding reveal that the complex kinematics in these flows yield similar types of orientation states to those observed in molded plaques and help better understand the evolution of time-dependent molecular orientation and crystallinity during mold filling and solidification.

  12. Processing-Structure-Property Relationships in Laser-Annealed PbSe Nanocrystal Thin Films.

    Science.gov (United States)

    Treml, Benjamin E; Robbins, Andrew B; Whitham, Kevin; Smilgies, Detlef-M; Thompson, Michael O; Hanrath, Tobias

    2015-04-28

    As nanocrystal (NC) synthesis techniques and device architectures advance, it becomes increasingly apparent that new ways of connecting NCs with each other and their external environment are required to realize their considerable potential. Enhancing inter-NC coupling by thermal annealing has been a long-standing challenge. Conventional thermal annealing approaches are limited by the challenge of annealing the NC at sufficiently high temperatures to remove surface-bound ligands while at the same time limiting the thermal budget to prevent large-scale aggregation. Here we investigate nonequilibrium laser annealing of NC thin films that enables separation of the kinetic and thermodynamic aspects of nanocrystal fusion. We show that laser annealing of NC assemblies on nano- to microsecond time scales can transform initially isolated NCs in a thin film into an interconnected structure in which proximate dots "just touch". We investigate both pulsed laser annealing and laser spike annealing and show that both annealing methods can produce "confined-but-connected" nanocrystal films. We develop a thermal transport model to rationalize the differences in resulting film morphologies. Finally we show that the insights gained from study of nanocrystal mono- and bilayers can be extended to three-dimensional NC films. The basic processing-structure-property relationships established in this work provide guidance to future advances in creating functional thin films in which constituent NCs can purposefully interact. PMID:25787088

  13. Quantitative Structure-Property Relationships for the Normal Boiling Temperatures of Acyclic Carbonyl Compounds

    Directory of Open Access Journals (Sweden)

    Ovidiu Ivanciuc

    2002-05-01

    Full Text Available Quantitative structure-property relationships (QSPR models for the estimation of normal boiling temperatures for a set of 200 acyclic carbonyl compounds (containing mono- and dialdehydes, mono- and diketones, keto aldehydes, and esters of monocarboxylic acids were established with the CODESSA program. The QSPR models developed with CODESSA allow accurate computation of the boiling temperatures of organic compounds using simple constitutional, topological, electrostatic and quantum indices that can be computed with standard quantum chemistry packages. For the group of 127 aldehydes and ketones, a good multiple linear regression equation was obtained using five theoretical descriptors, with the following statistical indices: r = 0.990, rLOO = 0.986, s = 5.3 °C, and F = 1190. Equally good results were obtained for the group of 73 esters (r = 0.993, rLOO = 0.991, s = 4.2 °C, and F = 906 and all 200 compounds (r = 0.988, rLOO = 0.987, s = 5.6 °C, and F = 1628. Our results show that an improvement in the prediction of the boiling temperatures of organic compounds can be obtained by developing models for classes of structurally related compounds.

  14. 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.

  15. Hierarchical multiscale structure-property relationships of the red-bellied woodpecker (Melanerpes carolinus) beak.

    Science.gov (United States)

    Lee, Nayeon; Horstemeyer, M F; Rhee, Hongjoo; Nabors, Ben; Liao, Jun; Williams, Lakiesha N

    2014-07-01

    We experimentally studied beaks of the red-bellied woodpecker to elucidate the hierarchical multiscale structure-property relationships. At the macroscale, the beak comprises three structural layers: an outer rhamphotheca layer (keratin sheath), a middle foam layer and an inner bony layer. The area fraction of each layer changes along the length of the beak giving rise to a varying constitutive behaviour similar to functionally graded materials. At the microscale, the rhamphotheca comprises keratin scales that are placed in an overlapping pattern; the middle foam layer has a porous structure; and the bony layer has a big centre cavity. At the nanoscale, a wavy gap between the keratin scales similar to a suture line was evidenced in the rhamphotheca; the middle foam layer joins two dissimilar materials; and mineralized collagen fibres were revealed in the inner bony layer. The nano- and micro-indentation tests revealed that the hardness (associated with the strength, modulus and stiffness) of the rhamphotheca layer (approx. 470 MPa for nano and approx. 320 MPa for micro) was two to three times less than that of the bony layer (approx. 1200 MPa for nano and approx. 630 MPa for micro). When compared to other birds (chicken, finch and toucan), the woodpecker's beak has more elongated keratin scales that can slide over each other thus admitting dissipation via shearing; has much less porosity in the bony layer thus strengthening the beak and focusing the stress wave; and has a wavy suture that admits local shearing at the nanoscale. The analysis of the woodpeckers' beaks provides some understanding of biological structural materials' mechanisms for energy absorption. PMID:24812053

  16. Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites

    Directory of Open Access Journals (Sweden)

    Drago Skrtic

    2009-11-01

    Full Text Available Our studies of amorphous calcium phosphate (ACP-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/remineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-?-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation.

  17. Relationship between crystal structure and solid-state properties of pharmaceuticals

    Science.gov (United States)

    Sheth, Agam R.

    This thesis strives to understand the structure-property relationships of some pharmaceutical crystals at the molecular level with emphasis on the effect of secondary processing on the solid phase. Using single crystal X-ray diffractometry (SCXRD), the structure of warfarin sodium 2-propanol adduct (W) was established to be a true solvate, contrary to previous reports. Using dynamic water vapor sorption, optical and environmental scanning electron microscopy, SCXRD, powder X-ray diffractometry (PXRD), volume computations and molecular modeling, the effect of relative humidity and temperature on the crystal structure of W was investigated. Ab initio calculations on piroxicam showed that the difference in energy between the two polymorphs, I and II, arises predominantly from the difference between their lattice energies. The detailed hydrogen bonding networks of the two polymorphs are described and compared using graph sets. Despite stabilization of the polymorphs by hydrogen bonds, pair-wise distribution function transforms show a loss of polymorphic memory upon cryogrinding the two polymorphs, leading to a difference in recrystallization behavior between amorphous piroxicam prepared from polymorphs I and II. Structural and solid-state changes of piroxicam polymorphs under mechanical stress were investigated using cryogenic grinding, PXRD, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, and diffuse-reflectance solid-state Fourier-transform infrared spectroscopy. Intermolecular proton transfer was found to accompany changes in phase and color observed upon cryogrinding the two polymorphs. Model-free and model-fitting studies of the dehydration kinetics of piroxicam monohydrate (PM) showed the dependence of activation energy ( Ea) on both isothermal and non-isothermal heating conditions, and on the fraction of conversion. In the constant-E a region, isothermal dehydration follows the two-dimensional phase boundary model, while non-isothermal dehydration follows a mechanism intermediate between two- and three-dimensional diffusion that cannot be described by any of the common models. Structural studies suggest that the complex hydrogen bond pattern in PM is responsible for the observed dehydration behavior. Ab initio calculations provide an explanation for the changes in the molecular and crystal structures accompanying the reversible change in hydration state between anhydrous piroxicam Form I and PM. The thesis further demonstrates the utility of model-free analysis in describing complex dehydration kinetics.

  18. Prediction of Henry's Law Constants via group-specific quantitative structure property relationships.

    Science.gov (United States)

    O'Loughlin, Darragh R; English, Niall J

    2015-05-01

    Henry's Law Constants (HLCs) for several hundred organic compounds in water at 25 °C were predicted by Quantitative Structure Property Relationship (QSPR) models, with the division of organic compounds into specific classes to yield more accurate models than generalised ones. Both multiple linear regression (MLR) and artificial neural network (ANN) versions of models were produced for three general cases, encompassing the entire data set; one used the six best descriptors, as determined by maximising the correlation coefficient; another used the twelve best descriptors in a similar manner, whilst the third used the same twelve descriptors as English and Carroll (2001). These achieved, respectively, root-mean square errors (RMSEs) of 0.719, 0.52 and 0.607 log(Hcc) units for the MLR version and 0.601, 0.394 and 0.431 for the test set of the ANN models, where Hcc is the ratio of the compound's concentration in the vapour phase to that in the liquid phase. These were compared with models for six specific chemical classes: (i) alkanes, (ii) cyclic alkanes, (iii) alkenes, (iv) halogenated compounds, (v) aldehydes, ketones and esters grouped together, and (vi) monoaromatics. These group-specific models had RMSEs of 0.153, 0.141. 0.097, 0.168, 0.122 and 0.104 respectively for the MLR versions and 0.684, 0.719, 0.856, 0.784, 0.875 and 0.861 for the test set of the ANN models. It was found that the class-specific models achieved lower RMSEs than the general models, when using MLR models. The use of ANN was found to improve the predictive accuracy of the general models but failed to improve that for the class-specific models vis-à-vis MLR. PMID:25602194

  19. Structure-dielectric property relationship for vanadium- and scandium-doped barium strontium titanate

    International Nuclear Information System (INIS)

    This paper reports the results of an investigation of the structure-property relationship of vanadium (donor) and scandium (acceptor) doped Ba0.7Sr0.3TiO3. While V doping produces a fully miscible Ba0.7Sr0.3Ti1-xV xO3 alloy, Sc doping results in an inhomogeneous microstructure with grains containing a Sc-doped Ba-rich shell and an undoped Sr-rich core. This results from a solution-precipitation process that works in combination with a thermodynamic driving force for the preferential segregation of Sc into Ba-rich regions. The Curie temperature (T c) of Ba0.7Sr0.3TiO3 decreases with increasing dopant concentration from a T c of 40 deg. C for undoped material to 18 deg. C for 4 mol.% V and 22 deg. C for 4 mol.% Sc (i.e., Ba0.7Sr0.3Ti0.96V0.04O3, Ba0.7Sr0.3Ti0.96Sc0.04O3). Sc- and V-doped materials are found to have significantly reduced dielectric constants at their Curie temperature than their undoped counterpart. This is most evident for Sc doping, where a 4 mol.% concentration has a dielectric constant of 1000 at T c, a factor of 12 times smaller than undoped Ba0.7Sr0.3TiO3

  20. The relationships between rheological properties and structural changes of chilled abalone meat

    Science.gov (United States)

    Xin, Gao; Zhaohui, Zhang; Zhixu, Tang; Yuri, Tashiro; Hiroo, Ogawa

    2003-10-01

    The quantitative correlation between rheological properties and structural characteristic values of chilled abalone meat was studied. Structural changes were observed, and these values were enumerated using image processing and analysis technique. Structural changes in the myofibrils and collagen fibrils were the greatest in chilling for 24 h. After chilling for 48 h, similar structures of vertical and cross sections were observed. For chilling from 0h to 72 h, the instantaneous modulus E 0 of the both section meat decreases gradually with time, but no significant differences were observed after chilling for 48h. The relaxation time and viscosity of both sections attained the same values for the same chilling time, but increased gradually with increasing chilling time. Meanwhile, a negative correlation between the structural characteristic values (Dm, Am, Rvm), and rheological properties (E 1, ? 1, ? 1) clearly exists. Some logarithmic expressions have been obtained for these negative correlation. These results suggest that the difference in rheological properties between the cross and vertical sections was mainly due to the structural changes of myofibrils and collagen fibrils, and rheological properties are influenced quantitatively by the structural characteristics values for chilling from 0 h to 72 h.

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

    International Nuclear Information System (INIS)

    Silicon carbide (SiC) is a promising candidate for several applications in nuclear reactors owing to its high thermal conductivity, high melting temperature, good chemical stability, and resistance to swelling under heavy ion bombardment. However, fabricating SiC by traditional powder processing route generally requires very high temperatures for pressureless sintering. Polymer derived ceramic materials offer unique advantages such as ability to fabricate net shaped components, incorporate reinforcements and relatively low processing temperatures. Furthermore, for SiC based ceramics fabricated using polymer infiltration process (PIP), the microstructure can be tailored by controlling the processing parameters, to get an amorphous, nanocrystalline or crystalline SiC. In this work, fabrication of polymer derived amorphous and nano-grained SiC is presented and its application as an in-core material is explored. Monolithic SiC samples are fabricated by controlled pyrolysis of allyl-hydrido-poly-carbo-silane (AHPCS) under inert atmosphere. Chemical changes, phase transformations and microstructural changes occurring during the pyrolysis process are studied as a function of the processing temperature. Polymer cross-linking and polymer to ceramic conversion is studied using infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are performed to monitor the mass loss and phase change as a function of temperature. X-ray diffractia function of temperature. X-ray diffraction studies are done to study the intermediate phases and microstructural changes. Variation in density is carefully monitored as a function of processing temperature. Owing to shrinkage and gas evolution during pyrolysis, precursor derived ceramics are inherently porous and composite fabrication typically involves repeated cycles of polymer re-infiltration and pyrolysis. However, there is a limit to the densification that can be achieved by this method and porosity in the final materials presents 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)

  2. 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 the fractal dimensions at the network and the individual fibril lengthscales are substantiated in the real space by cryo-TEM. Additionally, a study of the gel microstructure by USANS indicates well-defined microporosity, an important characteristic for cellular substrate applications. Preliminary cell viability and anchorage studies at varying hydrogel stiffness confirm cell adhesion at early stages of cell culture within the window of stiffness investigated. The universal applicability of the fractal model to hydrogel networks is demonstrated by doubly crosslinked hyaluronic acid based gels consisting of highly crosslinked hydrogel particles embedded in and covalently bonded to a loosely connected secondary network. An increase in the high q mass fractal dimension of the secondary network compared to gels with no particles is ascribed to the increase in the density of network due to addition of the crosslinked hydrogel particles. A morphological investigation of peptide amphiphiles discloses the delicate balance of hydrophobic and hydrophilic amino acids in these molecules leading to multiple, distinct nanostructures. Direct repercussions of the nanostructure on fibrillar aggregation, orientation, network and nematic behavior is seen. Finally, the dependence of molecular weight of a high molecular weight homopolypeptide, poly(L-lysine) on its secondary conformation in polypeptide-clay nanocomposites has been explored. The matrix polypeptide is found to fold into beta-sheets when cast as films irrespective of the initial secondary structure in solution, a tendency that is attributed to film casting conditions and high molecular weight.

  3. 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

    2015-01-01

    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. PMID:26108282

  4. Chitosan Polyplexes as Non-Viral Gene Delivery Systems : Structure-Property Relationships and In Vivo Efficiency

    OpenAIRE

    Ko?ping-ho?gga?rd, Magnus

    2003-01-01

    The subject of this thesis was to develop and optimize delivery systems for plasmid DNA (pDNA) based on biocompatible polymers, in particular chitosan, suitable for non-viral gene therapy. At the onset of this thesis, studies had reported conflicting results on the efficiency of chitosan-based gene delivery systems. Therefore, structure-property relationships of chitosans as non-viral gene delivery systems in vitro and after lung administration in vivo were established for the first time. Pol...

  5. Relationship Between Structural Fractal and Possible Dynamic Scaling Properties in Protein Folding

    OpenAIRE

    Zou, Liang-jian; Gong, X. G.; Zhu, Zheng-gang

    1996-01-01

    In this letter, the possible dynamic scaling properties of protein molecules in folding are investigated theoretically by assuming that the protein molecules are percolated networks. It is shown that the fractal character and the fractal dimensionality may exist only for short sequences in large protein molecules and small protein molecules with homogeneous structure, the fractal dimensionality are obtained for different structures. We then show that there might exist the dy...

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

    International Nuclear Information System (INIS)

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

  7. Structure–morphology–mechanical properties relationship of some polypropylene/lignocellulosic composites

    International Nuclear Information System (INIS)

    Natural lignocellulosic materials have an outstanding potential as thermoplastic reinforcement. Polypropylene composites were prepared using different types of lignocellulosic materials by melt blending of 70 wt% polypropylene (PP) and 30 wt% biomasses. The specimens were firstly evaluated for structural and morphological properties by infrared spectroscopy, X-ray diffraction, scanning electron and polarized optical microscopy. Depending on the biomass type, there were evidenced some particular shifts of the infrared bands and also crystallinity changes. An increase in crystallinity is explained by nucleating agent role of biomass. The morphological changes are directly related to variation in mechanical and rheological properties, an increase in Young modulus, melt viscosity and storage and loss moduli being recorded. - Highlights: • Composites based on polypropylene and different biomass filler were prepared by simple melting-mixing. • The specimens were evaluated for structural, morphological, mechanical and rheological properties. • The biomass filler act as a nucleation agent in the polymeric matrix

  8. Multiple Quantum NMR Investigations of Structure- Property Relationships in Synthetic and Aged Silicone Elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, R; Gjersing, E; Chinn, S; Herberg, J; Eastwood, E; Bowen, D; Stephens, T

    2006-09-27

    Complex engineering elastomeric materials are often characterized by a complex network structure obtained by crosslinking network chains with multiple chain lengths. Further, these networks are commonly filled with thixotropic reinforcing agents such as SiO{sub 2} or carbon black. Degradation of such materials often occurs via mechanisms that alter the fundamental network structure. In order to understand the effects of modifications of network structure and filler-polymer interaction on component performance, a series of model compounds have been studied by {sup 1}H multiple quantum NMR analysis and traditional mechanical property assessments. The {sup 1}H NMR data provides insight into the distribution of segmental dynamics that reveals insight into the changes in mechanical properties.

  9. 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...

  10. Water and moisture susceptibility of chitosan and paper-based materials: structure-property relationships.

    Science.gov (United States)

    Bordenave, N; Grelier, S; Pichavant, F; Coma, V

    2007-11-14

    Environmentally friendly and potentially bioactive food packaging based on chitosan-coated papers were elaborated. The morphology and the microstructure of these new materials were characterized by infrared spectroscopy and scanning electron microscopy. These observations suggested that the chitosan penetrated deeply into the paper, embedding the cellulose fibers, instead of forming a layer as expected. Through the barrier properties against moisture, the liquid water sensitivity, and NMR-relaxometry measurements, the water interactions were evaluated on the chitosan films and the chitosan-coated papers. They revealed that the coating by a chitosan film forming solution improved the paper moisture barrier properties but the surface hydrophilicity remained high. Relaxometry studies showed that, due to its hydrophilic character, chitosan controlled the interaction with water, despite the very low amount of deposit. On the other hand, the mechanical properties of papers were unmodified by the chitosan coating, which did not fundamentally affect the solid structure of the papers. PMID:17953443

  11. Structure-property relationships of curved aromatic materials from first principles.

    Science.gov (United States)

    Zoppi, Laura; Martin-Samos, Layla; Baldridge, Kim K

    2014-11-18

    CONSPECTUS: Considerable effort in the past decade has been extended toward achieving computationally affordable theoretical methods for accurate prediction of the structure and properties of materials. Theoretical predictions of solids began decades ago, but only recently have solid-state quantum techniques become sufficiently reliable to be routinely chosen for investigation of solids as quantum chemistry techniques are for isolated molecules. Of great interest are ab initio predictive theories for solids that can provide atomic scale insights into properties of bulk materials, interfaces, and nanostructures. Adaption of the quantum chemical framework is challenging in that no single theory exists that provides prediction of all observables for every material type. However, through a combination of interdisciplinary efforts, a richly textured and substantive portfolio of methods is developing, which promise quantitative predictions of materials and device properties as well as associated performance analysis. Particularly relevant for device applications are organic semiconductors (OSC), with electrical conductivity between that of insulators and that of metals. Semiconducting small molecules, such as aromatic hydrocarbons, tend to have high polarizabilities, small band-gaps, and delocalized ? electrons that support mobile charge carriers. Most importantly, the special nature of optical excitations in the form of a bound electron-hole pairs (excitons) holds significant promise for use in devices, such as organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), and molecular nanojunctions. Added morphological features, such as curvature in aromatic hydrocarbon structure, can further confine the electronic states in one or more directions leading to additional physical phenomena in materials. Such structures offer exploration of a wealth of phenomenology as a function of their environment, particularly due to the ability to tune their electronic character through functionalization. This Account offers discussion of current state-of-the-art electronic structure approaches for prediction of structural, electronic, optical, and transport properties of materials, with illustration of these capabilities from a series of investigations involving curved aromatic materials. The class of curved aromatic materials offers the ability to investigate methodology across a wide range of materials complexity, including (a) molecules, (b) molecular crystals, (c) molecular adsorbates on metal surfaces, and (d) molecular nanojunctions. A reliable pallet of theoretical tools for such a wide array relies on expertise spanning multiple fields. Working together with experimental experts, advancements in the fundamental understanding of structural and dynamical properties are enabling focused design of functional materials. Most importantly, these studies provide an opportunity to compare experimental and theoretical capabilities and open the way for continual improvement of these capabilities. PMID:24933397

  12. Structure-dielectric properties relationships in copper-substituted magnesium ferrites

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis of copper substituted magnesium ferrites materials is reported. • A shift from cubic to tetragonal structure starting with x = 0.84 was observed. • The dielectric properties are influenced by Cu-substitution. - Abstract: Nanocrystalline powders of copper-substituted magnesium ferrites with general formula Mg1?xCuxFe2O4 (x = 0.00, 0.17, 0.34, 0.50, 0.67, 0.84, 1.00) were prepared for the first time by sol–gel auto-combustion method, using glycine as fuel agent. Solid phase chemical reactions and the occurrence of spinel structure were monitored by using infrared spectroscopy. X-ray diffraction analysis confirmed the spinel single-phase formation. A shift from cubic structure to tetragonal structure starting with x = 0.84 was also observed. Microstructure of the samples was analyzed by scanning electron microscopy and particle size was estimated from the micrographs. Analysis of dielectric properties revealed very low values of dielectric loss at frequencies over 10 MHz

  13. Chemical Modification and Structure-property Relationships of Acrylic and Ionomeric Thermoplastic Elastomer Gels

    Science.gov (United States)

    Vargantwar, Pruthesh Hariharrao

    Block copolymers (BCs) have remained at the forefront of materials research due to their versatility in applications ranging from hot-melt/pressure-sensitive adhesives and impact modifiers to compatibilizing agents and vibration-dampening/nanotemplating media. Of particular interest are macromolecules composed of two or more chemically dissimilar blocks covalently linked together to form triblock or pentablock copolymers. If the blocks are sufficiently incompatible and the copolymer behaves as a thermoplastic elastomer, the molecules can spontaneously self-assemble to form nanostructured materials that exhibit shape memory due to the formation of a supramolecular network. The BCs of these types are termed as conventional. When BCs contain blocks having ionic moieties such as sulfonic acid groups, they are termed as block ionomers. Designing new systems based on either conventional or ionic BCs, characterizing their structure-property relationships and later using them as electroacive polymers form the essential objectives of this work. Electroactive polymers (EAPs) exhibit electromechanical actuation when stimulated by an external electric field. In the first part of this work, it is shown that BCs resolve some of the outstanding problems presently encountered in the design of two different classes of EAP actuators: dielectric elastomers (DEs) and ionic polymer metal composites (IPMCs). All-acrylic triblock copolymer gels used as DEs actuate with high efficacy without any requirement of mechanical prestrain and, thus, eliminate the need for bulky and heavy hardware essential with prestrained dielectric actuators, as well as material problems associated with stress relaxation. The dependence of actuation behavior on gel morphology as evaluated from mechanical and microstructure studies is observed. In the case of IPMCs, ionic BCs employed in this study greatly facilitate processing compared to other contenders such as NafionRTM, which is commonly used in this class of EAPs. The unique copolymer investigated here (i) retains its mechanical integrity when highly solvated by polar solvents, (ii) demonstrates a high degree of actuation when tested in a cantilever configuration, and (iii) avoids the shortcomings of back-relaxation/overshoot within the testing conditions when used in combination with an appropriate solvent. In the second part of this work, two chemical strategies to design midblock sulfonated block ionomers are explored. In one case, selective sulfonation of the midblocks in triblock copolymers is achieved via a dioxane:sulfur trioxide chemistry, while in the other acetyl sulfate is used for the same purpose. Excellent control on the degree of sulfonation (DOS) is achieved. The block ionomers swell in different solvents while retaining their mechanical integrity. They show disorder-order, order-order, and order-reduced order morphological transitions as DOS varies. These transitions in morphologies are reflected in their thermal behavior as well. The microstructures show periodicity, which is, again, a function of DOS. The transitions are explained in terms of the molar volume expansion and volume densification of the blocks on sulfonation. The ionic levels, morphology and periodicity in microstructure are important for applications such as actuators, sensors and fuel cell membranes. The ability to tune these aspects in the ionomers designed in this work make them potential candidates for these applications.

  14. Processing, structure, property and performance relationships for the thermal spray of the internal surface of aluminum cylinders

    Science.gov (United States)

    Cook, David James

    The increased need for automotive weight reduction has necessitated the use of aluminum for engine blocks. Conventional aluminum alloys cannot survive the constant wear from a piston ring reciprocating on the surface. However, a wear resistant thermal spray coating can be applied on the internal surface of the cylinder bore, which has significant advantages over other available options. Thermal spray is a well-established process for depositing molten, semi-molten, or solid particles onto a substrate to form a protective coating. For this application, the two main challenges were obtaining good wear resistance, and achieving good adhesion. To design a system capable of producing a well-adhered, wear resistant coating for this high volume application it is necessary to identify the overall processing, structure, properties, and performance relationships. The results will demonstrate that very important relationships exist among particle characteristics, substrate conditions, and the properties of the final coating. However, it is the scientific studies to understand some of the process physics in these relationships that allow recognition of the critical processing conditions that need to be controlled to ensure a consistent, reliable thermal spray coating. In this investigation, it will be shown that the critical microstructural aspect of the coating that produced the required tribological properties was the presence of wuestite (FeO). It was found that by using a low carbon steel material with compressed air atomizing gas, it was possible to create an Fe/FeO structure that exhibited excellent tribological properties. This study will also show that traditional thermal spray surface preparation techniques were not ideal for this application, therefore a novel alternative approach was developed. The application of a flux to the aluminum surface prior to thermal spray promotes excellent bond strengths to non-roughened aluminum. Analysis will show that this flux strips the oxide from the aluminum and allows for chemical bonding of the NiAl coating to the aluminum via the formation of intermetallics. By developing processing, structure, property, and performance relationships for the full process, it was possible to design a complete coating process to succeed in this application. The determination of these relationships and the underlying process physics improves reliability and instills confidence in the process.

  15. 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, 70B2 O3 -(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. J Biomed Mater Res Part A: 103: 2344-2354, 2015. PMID:25366812

  16. Structure-property relationships of iron-hydroxyapatite ceramic matrix nanocomposite fabricated using mechanosynthesis method.

    Science.gov (United States)

    Nordin, Jamillah Amer; Prajitno, Djoko Hadi; Saidin, Syafiqah; Nur, Hadi; Hermawan, Hendra

    2015-06-01

    Hydroxyapatite (HAp) is an attractive bioceramics due to its similar composition to bone mineral and its ability to promote bone-implant interaction. However, its low strength has limited its application as load bearing implants. This paper presented a work focusing on the improvement of HAp mechanical property by synthesizing iron (Fe)-reinforced bovine HAp nanocomposite powders via mechanosynthesis method. The synthesis process was performed using high energy milling at varied milling time (3, 6, 9, and 12h). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM). Its mechanical properties were investigated by micro-Vicker's hardness and compression tests. Results showed that milling time directly influenced the characteristics of the nanocomposite powders. Amorphous BHAp was formed after 9 and 12h milling in the presence of HPO4(2-) ions. Continuous milling has improved the crystallinity of Fe without changing the HAp lattice structure. The nanocomposite powders were found in spherical shape, agglomerated and dense after longer milling time. The hardness and Young's modulus of the nanocomposites were also increased at 69% and 66%, respectively, as the milling time was prolonged from 3 to 12h. Therefore, the improvement of the mechanical properties of nanocomposite was attributed to high Fe crystallinity and homogenous, dense structure produced by mechanosynthesis. PMID:25842138

  17. Structure/property relationships in sintered and thermally sprayed WC-Co

    Science.gov (United States)

    Wayne, S. F.; Sampath, S.

    1992-12-01

    Thermally sprayed WC-Co is widely used as a wear-resistant coating for a variety of applications. Although it is well established that thermal spray processes significantly affect chemistry, microstructure, and the phase distribution of WC-Co coatings, little is known about how these changes influence wear resistance. In this study, the microstructure and wear behavior of sintered and thermally sprayed WC-Co materials are examined. Powders of WC-12 wt% Co and WC-17 wt% Co were pressed and sintered, as well as thermally sprayed by high-velocity oxy-fuel (HVOF), air plasma spray (APS), and vacuum plasma spray (VPS) techniques. Results indicated considerable differences in the resulting microstructures, mechanical properties, and wear resistance. The thermally sprayed coatings showed anisotropic fracture toughness, whereas the sintered materials did not. It was also shown that a combined mechanical property/microstructure parameter, based on considerations of indentation fracture mechanisms, can be used in most cases to describe abrasive and erosive wear resistance of thermally sprayed WC-Co materials as follows: Wear resistance a? ({K_{IC}^{{3 8}} H^{{{1 2}}) ( {{V_f^{Co} }/{1 - V_f^{Co }}} ) where K ic is the indentation fracture toughness, H is hardness, and V Co f is the volume fraction of cobalt. This relationship provides a means for assessing wear resistance of WC-Co coatings intended for industrial applications requiring abrasion and/or erosion resistance.

  18. Structure-property relationships of an A36 steel alloy under dynamic loading conditions

    Science.gov (United States)

    Mayatt, Adam J.

    Structure-property quantification of an A36 steel alloy was the focus of this study in order to calibrate and validate a plasticity-damage model. The microstructural parameters included grain size, particle size, particle number density, particle nearest neighbor distances, and percent of ferrite and pearlite. The mechanical property data focused on stress-strain behavior under different applied strain rates (0.001/s, 0.1/s, and 1000/s), different temperatures (293 K and 573 K), and different stress states (compression, tension, and torsion). Notch tension tests were also conducted to validate the plasticity-damage model. Also, failure of an A36 I-beam was examined in cyclic loads, and the crack growth rates were quantified in terms of fatigue striation data. Dynamic strain aging was observed in the stress-strain behavior giving rise to an important point that there exists a critical temperature for such behavior.

  19. 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.

  20. A Quantitative Structure-Property Relationship (QSPR Study of Aliphatic Alcohols by the Method of Dividing the Molecular Structure into Substructure

    Directory of Open Access Journals (Sweden)

    Bin Cheng

    2011-04-01

    Full Text Available A quantitative structure–property relationship (QSPR analysis of aliphatic alcohols is presented. Four physicochemical properties were studied: boiling point (BP, n-octanol–water partition coefficient (lg POW, water solubility (lg W and the chromatographic retention indices (RI on different polar stationary phases. In order to investigate the quantitative structure–property relationship of aliphatic alcohols, the molecular structure ROH is divided into two parts, R and OH to generate structural parameter. It was proposed that the property is affected by three main factors for aliphatic alcohols, alkyl group R, substituted group OH, and interaction between R and OH. On the basis of the polarizability effect index (PEI, previously developed by Cao, the novel molecular polarizability effect index (MPEI combined with odd-even index (OEI, the sum eigenvalues of bond-connecting matrix (SX1CH previously developed in our team, were used to predict the property of aliphatic alcohols. The sets of molecular descriptors were derived directly from the structure of the compounds based on graph theory. QSPR models were generated using only calculated descriptors and multiple linear regression techniques. These QSPR models showed high values of multiple correlation coefficient (R > 0.99 and Fisher-ratio statistics. The leave-one-out cross-validation demonstrated the final models to be statistically significant and reliable.

  1. Combinatorial thin film methodology for rapid investigation of composition-structure-property relationship in complex multifunctional materials

    Science.gov (United States)

    Takeuchi, Ichiro

    2005-03-01

    We have developed thin film composition spread techniques to map compositional phase diagrams of multicomponent functional materials. Various combinatorial thin film deposition techniques including pulsed laser deposition, co-sputtering, and electron-beam deposition are used to fabricate binary and ternary composition spreads of metal oxide systems and metallic alloy systems. A variety of rapid characterization tools are employed to track physical properties of the materials as a function of sweeping composition changes. They include scanning SQUID microscopy, scanning microwave microscopy, and x-ray microdiffraction. High-throughput mapping of phase diagrams allow identification of new compounds as well as rapid delineation of composition-structure-property relationships. One of our emphases in these studies is to systematically look for structural phase transitions/boundaries in phase diagrams since these regions often display onset or peaking of ferroic properties such as ferroelectricity and magnetism. Mapping these active physical properties as a function of composition is an integral part of understanding the underlying physical mechanisms of the properties. To date, we have applied our methodology to investigation of a number of multifunctional materials including ferromagnetic shape memory alloys and magnetoelectric materials. We have demonstrated the utility of composition spreads as compact integrated devices where continuously changing physical parameters are used as a basis for functionally broadband detector arrays. The role of informatics in the high-throughput experimentation will also be discussed.

  2. Quantitative structure-property relationships generated with optimizable even/odd Wiener polynomial descriptors.

    Science.gov (United States)

    Ivanciuc, O; Ivanciuc, T; Klein, D J

    2001-01-01

    Chemical structures of organic compounds are characterized numerically by a variety of structural descriptors, one of the earliest and most widely used being the Wiener index W, derived from the interatomic distances in a molecular graph. Extensive use of distance-based structural descriptors or topological indices has been made in QSPR and QSAR models, drug design, toxicology, virtual screening of combinatorial libraries, similarity and diversity assessment. Novel topological indices are introduced representing a partitioning of the Wiener polynomial based on counts of even and odd molecular graph distances. During the QSAR/QSPR modeling process the variables of the even and odd power functions are optimized in order to offer an improved mapping of the investigated property. These novel topological indices are tested in QSPR models for the boiling temperature, molar heat capacity, standard Gibbs energy of formation, vaporization enthalpy, refractive index, and density of alkanes. In many cases, the even/odd Wiener polynomial indices proposed here give notably improved correlations or suggest simpler QSPR models. PMID:11697050

  3. 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...

  4. Structure and property relationships of amorphous CN sub x a joint experimental and theoretical study

    CERN Document Server

    Santos, M C D

    2000-01-01

    Amorphous CN sub x and CN sub x :H have been prepared by the ion beam assisted deposition technique. Samples were characterized through X-ray and UV photoemission, IR absorption and Raman spectroscopies. These spectra have been interpreted with the aid of quantum chemical calculations based upon the Hartree-Fock theory on several molecular models. The understanding of the electronic and structural properties of the amorphous alloy as a function of nitrogen content could help in the task of synthesizing the metastable silicon-nitride like-phase beta-C sub 3 N sub 4 , a solid which has been predicted to be as hard as diamond. The physical picture emerging from the present study helps to clarify the difficulties in obtaining the crystalline phase of the material, suggesting new experimental directions for syntheses.

  5. Structure-Property Relationships in Solid AlF3 Lewis Acids

    International Nuclear Information System (INIS)

    Understanding the structural cause of the high Lewis acidity in the novel solid Lewis acid AlF3 is of crucial importance to tailor this important material property to the specific needs of potential applications. Based on Al and F K-edge XAS studies, we are able to correlate high Lewis acidity with geometric distortions of the [AlF6] building blocks of AlF3. These distortions are induced by the presence of i-OPr ligands in the AlF3-x(i-OPr)x precursor material and can only be preserved by the application of a mild fluorinating agent like CCl2F2. High Lewis acidity is not caused by electronic modification of the aluminium atom, but by the better exposure of reactants to the acid site in the high surface area materials

  6. Structure-Property Relationships in Solid AlF3 Lewis Acids

    Science.gov (United States)

    Weiher, Norbert; Makarowicz, Anna; Beesley, Angela M.; Kemnitz, Erhard; Schroeder, Sven L. M.

    2007-02-01

    Understanding the structural cause of the high Lewis acidity in the novel solid Lewis acid AlF3 is of crucial importance to tailor this important material property to the specific needs of potential applications. Based on Al and F K-edge XAS studies, we are able to correlate high Lewis acidity with geometric distortions of the [AlF6] building blocks of AlF3. These distortions are induced by the presence of i-OPr ligands in the AlF3-x(i-OPr)x precursor material and can only be preserved by the application of a mild fluorinating agent like CCl2F2. High Lewis acidity is not caused by electronic modification of the aluminium atom, but by the better exposure of reactants to the acid site in the high surface area materials.

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

    Science.gov (United States)

    Pisarski, W A; Pisarska, J; M?czka, M; Lisiecki, R; Grobelny, ?; 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. PMID:21093353

  8. Structure and property relationships of amorphous CNx: a joint experimental and theoretical study

    Scientific Electronic Library Online (English)

    M.C. dos, Santos; F., Alvarez.

    Full Text Available Amorphous CNx and CNx:H have been prepared by the ion beam assisted deposition technique. Samples were characterized through X-ray and UV photoemission, IR absorption and Raman spectroscopies. These spectra have been interpreted with the aid of quantum chemical calculations based upon the Hartree-Fo [...] ck theory on several molecular models. The understanding of the electronic and structural properties of the amorphous alloy as a function of nitrogen content could help in the task of synthesizing the metastable silicon-nitride like-phase beta-C3N4 , a solid which has been predicted to be as hard as diamond. The physical picture emerging from the present study helps to clarify the difficulties in obtaining the crystalline phase of the material, suggesting new experimental directions for syntheses.

  9. Structure-property relationships in heterophasic thermoplastic elastomers filled with montmorillonite.

    Science.gov (United States)

    Causin, Valerio; Marega, Carla; Saini, Roberta; Neppalli, Ramesh; Ferrara, Giuseppe; Adhikari, Rameshwar; Marigo, Antonio

    2012-03-01

    Polypropylene (PP)/ethylene-propylene rubber (EPR)/Montmorillonite ternary nanocomposites with a phase separated morphology were studied in this work. Wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to investigate the samples. One of the aim of this work was to separate the effects of rubber and clay content on the structure, morphology and mechanical properties of the samples. The presence of clay favored the formation of gamma phase and disrupted the lamellar framework. Clay had moreover a major role in shaping the phase separated morphology of the samples. Atomic Force Microscopy showed that the shear exerted by the clay layers was key for inducing a shish kebab morphology in the polymer matrix. Rubber content decreased the degree of crystallinity at a crystalline cell level and induced the formation of a double population of lamellar stacks. The mechanical properties of the samples primarily depended on rubber content, and they were secondarily tuned by the effect of clay. This synergistic effect allowed to obtain composites with increased stiffness, ductility and toughness, oppositely to what is frequently found. PMID:22754991

  10. 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.

  11. Structure–property relationships of synthetic organophosphorus flame retardant oligomers by thermal analysis

    International Nuclear Information System (INIS)

    Highlights: • Oligomers with different chemical components in molecular chains were synthesized. • FP-3 containing three IFR components possessed high thermal stability. • FP-3 possessed lowest flammability. • FP-3 exhibited a synergistic interaction between gas and condensed phase. - Abstract: A series of flame retardant oligomers with different chemical components in molecular chains, designated as FP-1, FP-2 and FP-3, respectively, were successfully synthesized using solution polycondensation and well characterized. The thermal properties and flammability of these oligomers were investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The results demonstrated that FP-3 had the lowest flammability in terms of the lowest maximum mass loss rate, and FP-1 possessed the highest thermal stability and char yield, due to its higher stable hexatomic ring structure of piperazine compared with the linear alkane chain structure of neopentyl glycol. The gases evolved during decomposition were analyzed using Fourier transform infrared coupled with the thermogravimetric analyzer (TG–IR) technique. The char residues of the flame retardant oligomers were investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results demonstrated that FP-3 exhibited a synergistic interaction between the gas phase and condensation phase, increasing its flame retardancy

  12. New lanthanide-CB[6] coordination compounds: relationships between the crystal structure and luminescent properties.

    Science.gov (United States)

    da Silva, Fausthon F; de Oliveira, Carlos A F; Falcão, Eduardo H L; Chojnacki, Jaroslaw; Neves, Jorge L; Alves, S

    2014-04-14

    The reaction between cucurbit[6]uril (CB[6]) and lanthanide chlorides (Eu, Sm, Tb and Tm) in acidic aqueous media led to four new structures. The compounds obtained are isostructural with general formula [Ln2(H2O)12(H2O@CB[6])]Cl6(H2O)4 (Ln = Eu(3+) (1), Sm(3+) (2), Tb(3+) (3) and Tm(3+) (4)) and crystallize in the P21/c space group. For the complexes with Eu(3+), Sm(3+) and Tb(3+), the luminescent properties in the solid state and aqueous media were explored and all spectroscopic observations are in excellent agreement with the single crystal structure data. The excitation and emission spectra show the typical f-f transitions characteristic of the trivalent lanthanide ions. The transitions (7)FJ ? (5)D1 (J = 0,1,2) in the europium compound and (7)FJ ? (5)D4 (J = 0,1,2) in the terbium compound, not yet reported in lanthanide-CB[n] compounds, were also observed. PMID:24522452

  13. Relationship between crystal structure and mechanical properties of ranitidine hydrochloride polymorphs

    DEFF Research Database (Denmark)

    Upadhyay, Pratik Pankaj; Khomane, Kailas S.

    2013-01-01

    Polymorphism plays a critical role during pharmaceutical development, as it helps in the selection of optimal solid form. In present study, mechanical properties of ranitidine hydrochloride polymorphs were studied using instrumented tablet press, to understand the effect of crystal packing on the compaction behaviour. Out-of-die compressibility plot and Heckel analysis confirmed greater plastic deformation of form II over form I. Detailed crystallographic examination revealed that form I has several weak C-H?O interactions across the 'proposed slip plane' parallel to (-2 0 2) that prevent slip under compaction pressure. On the other hand, crystal structure of form II was relatively more open and multiple slip were possible under compaction pressure. These crystallographic features offered increased compressibility and deformability to form II. In absence of an active slip plane system, closed crystal structure of form I resists deformation under compaction pressure and hence showed poor compressibility and higher mean yield pressure. However, form I showed greater tabletability at a given compaction pressure, by virtue of its greater bonding strength. © 2013 The Royal Society of Chemistry.

  14. Structure–property relationships of synthetic organophosphorus flame retardant oligomers by thermal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Zhiman [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Wang, Xin; Tang, Gang; Song, Lei [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Lab of Fire Science, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026 (China); USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Yuen, Richard K.K., E-mail: Richard.Yuen@cityu.edu.hk [USTC-CityU Joint Advanced Research Centre, Suzhou Key Laboratory of Urban Public Safety, Suzhou Institute for Advanced Study, University of Science and Technology of China, 166 Ren’ai Road Suzhou, Jiangsu 215123 (China); Department of Building and Construction, City University of Hong Kong, Tat Chee Avenue Kowloon (Hong Kong)

    2013-08-10

    Highlights: • Oligomers with different chemical components in molecular chains were synthesized. • FP-3 containing three IFR components possessed high thermal stability. • FP-3 possessed lowest flammability. • FP-3 exhibited a synergistic interaction between gas and condensed phase. - Abstract: A series of flame retardant oligomers with different chemical components in molecular chains, designated as FP-1, FP-2 and FP-3, respectively, were successfully synthesized using solution polycondensation and well characterized. The thermal properties and flammability of these oligomers were investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The results demonstrated that FP-3 had the lowest flammability in terms of the lowest maximum mass loss rate, and FP-1 possessed the highest thermal stability and char yield, due to its higher stable hexatomic ring structure of piperazine compared with the linear alkane chain structure of neopentyl glycol. The gases evolved during decomposition were analyzed using Fourier transform infrared coupled with the thermogravimetric analyzer (TG–IR) technique. The char residues of the flame retardant oligomers were investigated by scanning electron microscopy (SEM) and Raman spectroscopy. The results demonstrated that FP-3 exhibited a synergistic interaction between the gas phase and condensation phase, increasing its flame retardancy.

  15. Structure-property relationships in multilayered polymeric system and olefinic block copolymers

    Science.gov (United States)

    Khariwala, Devang

    Chapter 1. The effect of tie-layer thickness on delamination behavior of polypropylene/tie-layer/Nylon-6 multilayers is examined in this study. Various maleated polypropylene resins were compared for their effectiveness as tie-layers. Delamination failure occurred cohesively in all the multilayer systems. Two adhesion regimes were defined based on the change in slope of the linear relationship between the delamination toughness and the tie-layer thickness. The measured delamination toughness of the various tie-layers was quantitatively correlated to the damage zone length formed at the crack tip. In addition, the effect of tie-layer thickness on the multilayer tensile properties was correlated with the delamination behavior. The fracture strain of the multilayers decreased with decreasing tie-layer thickness. Examination of the prefracture damage mechanism of stretched multilayers revealed good correlation with the delamination toughness of the tie-layers. In thick tie-layers (>2microm) the delamination toughness of the tie-layers was large enough to prevent delamination of multilayers when they were stretched. In the thin tie-layers (synthesis give rise to olefinic block copolymers with properties typical of thermoplastic elastomers. The block copolymers synthesized by chain shuttling technology consist of crystallizable ethylene-octene blocks with low comonomer content and high melting temperature (hard blocks), alternating with amorphous ethylene-octene blocks with high comonomer content and low glass transition temperature (soft blocks). This study describes the material science of these unique polymers as characterized by thermal analysis, X-ray diffraction, microscopy, and tensile deformation. The crystallizable blocks are long enough to form well-organized lamellar crystals with the orthorhombic unit cell and high melting temperature. The lamellae are organized into space-filling spherulites in all compositions even in copolymers with only 18 wt% hard block. The morphology is consistent with crystallization from a miscible melt. Crystallization of the hard blocks forces segregation of the noncrystallizable soft blocks into the interlamellar regions. Good separation of hard and soft blocks in the solid state is confirmed by distinct and separate beta- and alpha-relaxations in all the block copolymers. Compared to statistical ethylene-octene copolymers, the blocky architecture imparts a substantially higher crystallization temperature, a higher melting temperature and a better organized crystalline morphology, while maintaining a lower glass transition temperature. The differences between blocky and statistical copolymers become progressively more apparent as the total c

  16. Relationships between grade determining properties of Spanish scots and laricio pine structural timber

    Directory of Open Access Journals (Sweden)

    Fernández-Golfín, J. I.

    2003-06-01

    Full Text Available In a. sample made up of 3312 boards of scots pine (pinus sylvestris and 3318 boards of laricio pine pinus nigra Van Saltzmannii, both of Spanish provenance, and ranging in size from 100x40x2500 mm to 200x70x4500 mm, previously tested in accordance with the procedure set forth in UNE EN 408 standard, the relationships between the grade determining properties considered in the UNE EN 338 standard (bending strength, global and local modulus of elasticity in bending, density are studied. In addition to these variables, the modulus of elasticity was also considered, calculated by means of the measuring of the transmission speed of an ultrasonic pulse generated by a Sylvatest device. The global modulus of elasticity calculated by measuring the deformation at the neutral axis seems to be the best predictor of the ultimate bending strength, while the local modulus of elasticity proves to be difficult to obtain, and has a lower predictive quality, and so its elimination is suggested. The need to consider one single testing procedure to determine the global modulus of elasticity is also analyzed, along with the convenience of carrying out further studies regarding the use of ultrasonic techniques in order to predict the modulus of elasticity, due to the fact that the systems available are not sufficiently precise.

    En una muestra compuesta por 3.312 piezas de madera aserrada de pino laricio (pimis nigra y 3.318 piezas de pino silvestre (pinus sylvestris de procedencia española y con dimensiones que varían entre 100x40x2.500 mm y 200x70x4.500 mm, previamente ensayada a flexión de acuerdo con el procedimiento descrito en la norma UNE EN 408, se analizan las relaciones existentes entre las propiedades indicadoras establecidas en la norma UNE EN 338 (resistencia última a flexión, módulos de elasticidad global y local en flexión, densidad. Adicionalmente a estas variables se determinó también el módulo de elasticidad obtenido mediante la medición de la velocidad de propagación de pulsos ultrasónicos generados por un equipo Sylvatest. El módulo de elasticidad global determinado mediante la medición de la deformación en la fibra neutra demuestra ser el mejor predictor de la resistencia última a la flexión, en tanto que el módulo de elasticidad local resulta ser de difícil ensayo y de inferior calidad predictiva, de donde sugiere su eliminación. Se concluye también sobre la necesidad de considerar un único ensayo para la determinación del módulo de elasticidad global y la conveniencia de seguir trabajando sobre la determinación del módulo de elasticidad mediante técnicas de ultrasonidos ya que los actuales sistemas disponibles todavía no alcanzan el suficiente grado de precisión.

  17. Structure-property relationships in centrifugally cast IMI 550 (Ti4Al-4Mo-2Sn-0.5Si)

    International Nuclear Information System (INIS)

    Centrifugal casting technology has been used to produce test pieces and hard-point bracket components for a determination of the structure-property relationships in the age-hardenable titanium alloy IMI 550. Tensile, high cycle fatigue, fracture toughness and elevated temperature creep results have shown that an attractive combination of property levels can be achieved in this alloy. It has been established that the tensile, fatigue and creep performance of cast plus Hot Isostatically Pressed (HIP) IMI 550 approaches that of conventionally wrought material while fracture toughness is superior. The improvement obtained in fracture toughness is a direct result of the presence of the highly acicular Widmanstatten or transformed beta microstructure produced by casting compared with the more traditional equiaxed alpha + beta structure exhibited by wrought products. HIP'ing has been shown to eliminate all traces of as cast internal shrinkage porosity and to thus yield a dramatic improvement in high cycle fatigue performance. HIP'ing was accompanied by general coarsening of the acicular alpha phases present in the micro-structure after casting. Macro and microstructural analysis of the castings indicated a refined and uniform beta grain size which it is believed is due to the presence of silicon in the alloy. 16 references

  18. The geometric properties of reduced canonically symplectic spaces with symmetry, their relationship with structures on associated principal fiber bundles and some applications. Part 1

    Directory of Open Access Journals (Sweden)

    Yarema A. Prykarpatsky

    2005-01-01

    Full Text Available The canonical reduction method on canonically symplectic manifolds is analized in detail, the relationships with the geometric properties of associated principal fiber bundles endowed with connection structures are stated. Some results devoted to studying geometrical properties of nonabelian Yang–Mills type gauge field quations are presented.

  19. Investigation on the structure-electrical property relationship of hydrolyzed poly(vinyl alcohol) membranes

    Scientific Electronic Library Online (English)

    J.F., Jurado; O., Checa; R.A., Vargas.

    2013-10-01

    Full Text Available This investigation explored the effects of the pre-treatment temperature on the molecular conformations and electrical performance of poly(vinyl alcohol) (PVOH) membranes. The structure and properties of the membranes were characterized by X-ray diffraction (XRD), differential scanning calorimetry ( [...] DSC), thermogravimetric analysis (TGA), Raman scattering (RS) and impedance measurements (IE). Water molecules absorbed by the PVOH membranes, which decreased in quantity as the temperature increased caused drastic change to be observed in the relative band intensities of the OH and CH2 bonds with respect to the C-C bonds. The observations for the hydrated PVOH were correlated with the proton transport behavior, which were inferred from conductivity relaxation measurements over various temperature regions and were dependent on the water content in the membrane. The results were corroborated by DSC and TGA. For example, the temperature dependence of the conductivity relaxation frequency, ?max, followed different Arrhenius-type thermally activated processes at low and high temperatures. The corresponding activation energies in the low and high temperature regions were: 1.42±0.02 and 0.23±0.02 eV, respectively. In addition, the selected fitting temperature regions and activation energies for the ?max data were equivalent (within experimental error) to the values for the dc-conductivity, ?0(T). This result indicates that the mechanisms for long range ion displacement (dc conductivity) and ion-ion or ion-polymer chain correlations are identical, (i.e., an ion-hoping occurred in the various hydrated phases of PVOH).

  20. Polytellurophenes provide imaging contrast towards unravelling the structure–property–function relationships in semiconductor:insulator polymer blends

    KAUST Repository

    Jahnke, Ashlee A.

    2015-02-27

    Polymer blends are broadly important in chemical science and chemical engineering and have led to a wide range of commercial products, however their precise structure and phase morphology is often not well understood. Here we show for the first time that ?-conjugated polytellurophenes and high-density polyethylene form blends that can serve as active layers in field-effect transistor devices and can be characterized by a variety of element-specific imaging techniques such as STEM and EDX. Changing the hydrocarbon content and degree of branching on the polytellurophene side-chain leads to a variety of blend structures, and these variations can be readily visualized. Characterization by electron microscopy is complemented by topographic and X-ray methods to establish a nano- to micro-scale picture of these systems. We find that blends that possess microscale networks function best as electronic devices; however, contrary to previous notions a strong correlation between nanofiber formation and electrical performance is not observed. Our work demonstrates that use of organometallic polymers assists in clarifying relevant structure–property–function relationships in multicomponent systems such as semiconductor:insulator blends and sheds light on the structure development in polymer:polymer blends including crystallization, phase separation, and formation of supramolecular arrangements.

  1. Carbene complexes with two chromium central atoms: relationship between structure and redox properties.

    Czech Academy of Sciences Publication Activity Database

    Metelková, R.; Tobrman, T.; Ludvík, Ji?í; Hoskovcová, I.

    Prague : International Society of Electrochemistry, 2012. [Annual ISE Meeting /63./. 19.08.2012-24.08.2012, Prague] Institutional support: RVO:61388955 Keywords : carbene complexes * redox properties * electrochemistry Subject RIV: CG - Electrochemistry

  2. ZrN based Nanostructured Hard Coatings : Structure-Property Relationship

    OpenAIRE

    Yalamanchili, Phani Kumar

    2014-01-01

    Ever since the hard coatings have been introduced, there has been a constant push for better mechanical properties, which motivates for deeper understanding of the microstructure-mechanical properties correlation. The aim of this thesis is to extend the knowledge on how microstructural variation influences the deformation, fracture and wear behavior of ZrN based nanostructured coatings. Few microns thick, monolithic Zr-Si-N and multilayered Zr-Al-N coatings were deposited by reactive arc depo...

  3. Carbene complexes with two chromium central atoms: relationship between structure and redox properties.

    Czech Academy of Sciences Publication Activity Database

    Metelková, R.; Tobrman, T.; Ludvík, Ji?í; Hoskovcová, I.

    Lisbon : Technical University of Lisbon, 2012. [International Conference on Organometallic Chemistry /25./. 02.09.2012-07.09.2012, Lisbon] Grant ostatní: GA MŠk(CZ) 21/2012 Institutional support: RVO:61388955 Keywords : carbene complexes * redox properties * chromium central atoms Subject RIV: CG - Electrochemistry

  4. Quantitative structure-property relationship (QSPR) model for predicting acidities of ketones

    OpenAIRE

    Yan Zhang; Yunyun Yuan; Philip D. Mosier

    2012-01-01

    Ketones are one of the most common functional groups, and ketone-containing compounds are essential in both the nature and the chemical sciences. As such, the acidities (pKa) of ketones provide valuable information for scientists to screen for biological activities, to determine physical properties or to study reaction mechanisms. Direct measurements of pKa of ketones are not readily available due to their extremely weak acidity. Hence, a quantita...

  5. About Your Child's Eating: factor structure and psychometric properties of a feeding relationship measure.

    Science.gov (United States)

    Davies, W Hobart; Ackerman, Lynn K; Davies, Cheryl M; Vannatta, Kathryn; Noll, Robert B

    2007-12-01

    Conducted exploratory and confirmatory factor analysis of the About Your Child's Eating (AYCE) inventory with 763 parents. Parent subjects were drawn from a community study of families with physically healthy and chronically ill children between 8 and 16 years of age. Three correlated factors were identified: Child Resistance to Eating, Positive Mealtime Environment, and Parent Aversion to Mealtime. The internal consistency of the factors remained satisfactory across all examined demographic subgroups. Evidence for convergent validity was found by comparing the AYCE factors to higher order factors of the Family Environment Scale. Empirically derived clinical range cut-off scores are presented. Results support the AYCE as a psychometrically sound measure of the parent-child feeding relationship for school-aged children. PMID:17950934

  6. Tribology, UV degradation, and structure-property-processing relationships of detonation nanodiamond-polyethylene nanocomposites

    Science.gov (United States)

    Tipton, John

    Nanoscale reinforcements offer the possibility of coupling the already proven high strength to weight properties of polymer matrix composites with additional multifunctional properties such as electrical conductivity, thermal conductivity, unique optics, UV/IR radiation absorption, and enhanced wear resistance. This work presents materials based on detonation nanodiamonds dispersed in two types of polyethylene. The work begins with an understanding of nucleation phenomena. It was discovered through isothermal kinetics using differential scanning calorimetry that nanodiamonds act as nucleating agents during polyethylene crystallization. A processing technique to disperse nanodiamonds into very viscous ultra-high molecular weight polyethylene was developed and analyzed. These composites were further studied using dynamic mechanical analysis which showed increases in both stiffness and energy absorbing modes over unfilled UHMWPE. Exposure to UV degradation caused a failure of the polymer microstructure which was found to be caused by residual tensile stresses between the polymer particles formed during processing. These high stress regions were more prone to photo oxidation even though the nanodiamond particles were shown to decrease surface oxidation. Additionally, the tribological properties of UHMWPE/nanodiamond composites were investigated. Ultra-high molecular weight polyethylene is an already proven ultra tough and wear resistant polymer that is used in many high performance thermoplastic applications such as bearings, surfaces (skids/wheels), ropes/nets, and orthopedic implants. This work showed that UHMWPE loaded with 5.0wt% nanodiamonds might be a candidate to replace the currently used crosslinked polyethylene material used in orthopedic implants.

  7. Does alkyl chain length really matter? Structure–property relationships in thermochemistry of ionic liquids

    International Nuclear Information System (INIS)

    Graphical abstract: We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies of alkylsubstituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with Cl and Br anions are linearly dependant on the alkyl chain length. The thermochemical properties of ILs are generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization are very close to those for molecular compounds. - Highlights: • Alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were studied using DSC and ab initio methods. • The thermochemical properties of ILs generally obey the group additivity rules. • A linear dependence on the chain length of the alkyl chain of cation was found. - Abstract: DSC was used for determination of reaction enthalpies of synthesis of ionic liquids [Cnmim][Cl]. A combination of DSC with quantum chemical calculations presents an indirect way to study thermodynamics of ionic liquids. The indirect procedure for vaporization enthalpy was validated with the direct experimental measurements by using thermogravimetry. First-principles calculations of the enthalpy of formation in the gaseous phase have been performed for the ionic species using the CBS-QB3 and G3 (MP2) theory. Experimental DSC data for homologous series of alkyl substituted imidazolium, pyridinium, and pyrrolidinium based ionic liquids with anions [Cl] and [Br] were collected from the literature. We have shown that enthalpies of formation, enthalpies of vaporization, and lattice potential energies are linearly dependant on the alkyl chain length. The thermochemical properties of ILs generally obey the group additivity rules and the values of the additivity parameters for enthalpies of formation and vaporization seem to be very close to those for molecular compounds

  8. Some aspects of the structure-property relationships in 12% Cr steels

    International Nuclear Information System (INIS)

    The inter-relations between solution treatment and tempering conditions and the microstructure, impact and 5500C stress-rupture properties of 12% Cr steels containing Mo, V and Nb additions have been avaluated. It was shown that reductions in impact transition temperature and increases in toughness and rupture ductility could be achieved, by suitable choice of heat treatment, but only at the expense of lowering the rupture strength. Inclusion shape control additions (Ze or rare earths) to the 12% CrMoVNb steel minimised directional anisotropy of toughness but marginally reduced the rupture strength and increased the rupture ductility. (author)

  9. Structural and phase transformations in Zr-Nb binary alloys and their relationship to the properties

    International Nuclear Information System (INIS)

    Using the methods of transmission electron microscopy and X-ray diffraction analysis the study was made of binary zirconium alloys, containing from 0.05 to 20 wt.% niobium, after different heat treatments. A substantial dependence is shown of the alloy properties on niobium content in solid solutions and on the volume ratio of the phases (?sub(Zr), ?sub(Zr), ?sub(Nb)?, ?, ?, ?). Niobium content increase in the supersaturated solid solution leads to an increase in strength and a decrease in corrosion resistance of the alloys under investigation

  10. Camel and bovine chymosin: the relationship between their structures and cheese-making properties

    Energy Technology Data Exchange (ETDEWEB)

    Langholm Jensen, Jesper [University of Copenhagen, (Denmark); Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm (Denmark); Mølgaard, Anne; Navarro Poulsen, Jens-Christian [University of Copenhagen, (Denmark); Harboe, Marianne Kirsten [Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm (Denmark); Simonsen, Jens Bæk [University of Copenhagen, (Denmark); Lorentzen, Andrea Maria; Hjernø, Karin [University of Southern Denmark, (Denmark); Brink, Johannes M. van den; Qvist, Karsten Bruun [Chr. Hansen A/S, Bøge Allé 10-12, DK-2970 Hørsholm (Denmark); Larsen, Sine, E-mail: sine@chem.ku.dk [University of Copenhagen, (Denmark)

    2013-05-01

    Analysis of the crystal structures of the two milk-clotting enzymes bovine and camel chymosin has revealed that the better milk-clotting activity towards bovine milk of camel chymosin compared with bovine chymosin is related to variations in their surface charges and their substrate-binding clefts. Bovine and camel chymosin are aspartic peptidases that are used industrially in cheese production. They cleave the Phe105-Met106 bond of the milk protein ?-casein, releasing its predominantly negatively charged C-terminus, which leads to the separation of the milk into curds and whey. Despite having 85% sequence identity, camel chymosin shows a 70% higher milk-clotting activity than bovine chymosin towards bovine milk. The activities, structures, thermal stabilities and glycosylation patterns of bovine and camel chymosin obtained by fermentation in Aspergillus niger have been examined. Different variants of the enzymes were isolated by hydrophobic interaction chromatography and showed variations in their glycosylation, N-terminal sequences and activities. Glycosylation at Asn291 and the loss of the first three residues of camel chymosin significantly decreased its activity. Thermal differential scanning calorimetry revealed a slightly higher thermal stability of camel chymosin compared with bovine chymosin. The crystal structure of a doubly glycosylated variant of camel chymosin was determined at a resolution of 1.6 Å and the crystal structure of unglycosylated bovine chymosin was redetermined at a slightly higher resolution (1.8 Å) than previously determined structures. Camel and bovine chymosin share the same overall fold, except for the antiparallel central ?-sheet that connects the N-terminal and C-terminal domains. In bovine chymosin the N-terminus forms one of the strands which is lacking in camel chymosin. This difference leads to an increase in the flexibility of the relative orientation of the two domains in the camel enzyme. Variations in the amino acids delineating the substrate-binding cleft suggest a greater flexibility in the ability to accommodate the substrate in camel chymosin. Both enzymes possess local positively charged patches on their surface that can play a role in interactions with the overall negatively charged C-terminus of ?-casein. Camel chymosin contains two additional positive patches that favour interaction with the substrate. The improved electrostatic interactions arising from variation in the surface charges and the greater malleability both in domain movements and substrate binding contribute to the better milk-clotting activity of camel chymosin towards bovine milk.

  11. Camel and bovine chymosin: the relationship between their structures and cheese-making properties

    International Nuclear Information System (INIS)

    Analysis of the crystal structures of the two milk-clotting enzymes bovine and camel chymosin has revealed that the better milk-clotting activity towards bovine milk of camel chymosin compared with bovine chymosin is related to variations in their surface charges and their substrate-binding clefts. Bovine and camel chymosin are aspartic peptidases that are used industrially in cheese production. They cleave the Phe105-Met106 bond of the milk protein ?-casein, releasing its predominantly negatively charged C-terminus, which leads to the separation of the milk into curds and whey. Despite having 85% sequence identity, camel chymosin shows a 70% higher milk-clotting activity than bovine chymosin towards bovine milk. The activities, structures, thermal stabilities and glycosylation patterns of bovine and camel chymosin obtained by fermentation in Aspergillus niger have been examined. Different variants of the enzymes were isolated by hydrophobic interaction chromatography and showed variations in their glycosylation, N-terminal sequences and activities. Glycosylation at Asn291 and the loss of the first three residues of camel chymosin significantly decreased its activity. Thermal differential scanning calorimetry revealed a slightly higher thermal stability of camel chymosin compared with bovine chymosin. The crystal structure of a doubly glycosylated variant of camel chymosin was determined at a resolution of 1.6 Å and the crystal structure of unglycosylated bovine chymosin was redetermined at a slightly higher resolution (1.8 Å) than previously determined structures. Camel and bovine chymosin share the same overall fold, except for the antiparallel central ?-sheet that connects the N-terminal and C-terminal domains. In bovine chymosin the N-terminus forms one of the strands which is lacking in camel chymosin. This difference leads to an increase in the flexibility of the relative orientation of the two domains in the camel enzyme. Variations in the amino acids delineating the substrate-binding cleft suggest a greater flexibility in the ability to accommodate the substrate in camel chymosin. Both enzymes possess local positively charged patches on their surface that can play a role in interactions with the overall negatively charged C-terminus of ?-casein. Camel chymosin contains two additional positive patches that favour interaction with the substrate. The improved electrostatic interactions arising from variation in the surface charges and the greater malleability both in domain movements and substrate binding contribute to the better milk-clotting activity of camel chymosin towards bovine milk

  12. 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.

  13. Relationship between Dielectric Properties and Oxygen Defect Structure of Nondoped CeO2

    Science.gov (United States)

    Saito, Miwa; Takayama, Toshio; Yamamura, Hiroshi

    2009-12-01

    The dielectric properties of CeO2, which was annealed at 1273 K in O2, air, and Ar atmospheres for the as-sintered specimens, were investigated in the temperature range from 673 to 1073 K. The frequency dependences of dielectric constant (?r') and dielectric loss factor (?r'') were successfully explained by Debye-type polarization model. The observed values of dielectric loss tangent (tan ?) and ac electrical conductivity (?ac) agreed with the values calculated using the dielectric parameters estimated from the analyses of ?r' and ?r''. It was found that the dielectric parameters such as Debye-type polarization (?ro1), relaxation frequency (?o1), and ac conductivity (?ac) increased with increasing oxygen vacancy concentration, which depends on the oxygen partial pressure in the annealing atmospheres.

  14. Predicting the adsorption properties of carbon dioxide corrosion inhibitors using a structure-activity relationship

    Energy Technology Data Exchange (ETDEWEB)

    Kinsella, B.; De Marco, R.; Jefferson, A.; Pejcic, B. [Western Australian Corrosion Research Group, Department of Applied Chemistry, Curtin University of Technology, GPO Box U1987, Perth, 6845, WA (Australia); Durnie, W. [Nalco/Exxon Energy Chemicals Ltd, Hardley, Hythe, Southampton (Australia)

    2004-07-01

    This paper presents a study of the influence of various chemical inhibitors on the corrosion rate of mild steel in brine electrolyte under carbon dioxide conditions. The performances as corrosion inhibitors were fitted to a Temkin adsorption isotherm, and various constants of adsorption (i.e., adsorption equilibrium constants and molecular interaction constants) have been obtained. The inhibitor adsorption mechanism has been discussed in terms of thermodynamics (i.e., {delta}H, {delta}G and {delta}S) and this revealed that some compounds chemisorbed onto the steel electrode. In addition, molecular modelling was undertaken using PCSPARTAN Plus and HyperChem Professional, and the various molecular parameters have been correlated with the thermodynamic adsorption properties of the inhibitors. A four-parameter fit for both negative and positive charged molecules is discussed. (authors)

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

    International Nuclear Information System (INIS)

    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.

  16. Structure property relationship of biological nano composites studies by combination of in-situ synchrotron scattering and mechanical tests

    International Nuclear Information System (INIS)

    Biological materials represent hierarchical nano fibre composites with complicated morphology and architecture varying on the nm level. The mechanical response of those materials is influenced by many parameters like chemical composition and crystal structure of constituents, preferred orientation, internal morphology with specific sizes of features etc. In-situ wide-angle x-ray scattering (WAXS) combined with mechanical tests provide a unique means to evaluate structural changes in biological materials at specific stages of tensile experiments. In this way it is possible to identify distinct architectural/compositional elements responsible for specific mechanical characteristics of the biological materials. In this thesis, structure-property relationship is analyzed using in-situ WAXS in the tissues of Picea abies, coir fibre, bacterial cellulose and cellulose II based composites. The experiments were performed at the beamline ID01 of European synchrotron radiation facility in Grenoble, France. The tissues were strained in a tensile stage, while the structural changes were monitored using WAXS. Complex straining procedures were applied including cyclic straining. One of the main goals was to understand the stiffness recovery and strain hardening effects in the tissues. The results demonstrate that, in all cellulosics, the orientation of the cellulose crystallites is only the function of the external strain while the stiffness depends on the specific stage of the tens depends on the specific stage of the tensile experiment. Whenever the strain is increased, the tissues exhibit stiffness equal or larger than the initial one. The recovery of the mechanical function is attributed to the molecular mechanistic effects operating between the crystalline domains of the cellulose. (author)

  17. Use of Quantitative Structure-Property Relationships in Predicting the Krafft Point of Anionic Surfactants

    Directory of Open Access Journals (Sweden)

    Mehdi Jalali-Heravi

    2002-08-01

    Full Text Available The Krafft point is the temperature at which the solubility of hydrated surfactants crystals increases sharply with increasing temperature. Also, the concentration at which micelles are formed at the Krafft temperature is the critical micelle concentration (CMC. Therefore, knowing the Krafft point and CMC of the surfactants is important and one should have information about the conditions in which a surfactant acts. This is useful to select an appropriate surfactant for a special application. The linear relationship between the descriptors and Krafft point of anionic surfactants was modeled using multiple linear regression technique. Linear models were generated using a stepwise regression model. A set of 32 linear alkyl sulfates [RSO4Na] and sulfonates [RSO3Na], sulfates and sulfunates with an ether or ester linkage to the hydrophobic tail [R(OCH2CH2nSO4Na], [RCOO(CH2nSO3Na] were used for model generation. Among different models, two equations were selected for their good statistical results. Specification of the best model in agreement with the experiment indicates that four descriptors consisting of the Randic index, heat of formation, reciprocal of the dipole moment, and reciprocal of the volume of tail of the molecule play a major role in the prediction of Krafft point of anionic surfactants. The statistics of the best models together with the cross-validation results indicate the capability of both models in predicting the Krafft point of anionic surfactants. Different strategies, including the Akaike Information Criterion (AIC, were used for choosing the best model. It was demonstrated that the Krafft point of these compounds depends on electronic descriptors and topological characteristics, such as compactness and branching of anionic surfactants.

  18. Camel and bovine chymosin : the relationship between their structures and cheese-making properties

    DEFF Research Database (Denmark)

    Jensen, Jesper Langholm; MØlgaard, Anne

    2013-01-01

    Bovine and camel chymosin are aspartic peptidases that are used industrially in cheese production. They cleave the Phe105-Met106 bond of the milk protein ?-casein, releasing its predominantly negatively charged C-terminus, which leads to the separation of the milk into curds and whey. Despite having 85% sequence identity, camel chymosin shows a 70% higher milk-clotting activity than bovine chymosin towards bovine milk. The activities, structures, thermal stabilities and glycosylation patterns of bovine and camel chymosin obtained by fermentation in Aspergillus niger have been examined. Different variants of the enzymes were isolated by hydrophobic interaction chromatography and showed variations in their glycosylation, N-terminal sequences and activities. Glycosylation at Asn291 and the loss of the first three residues of camel chymosin significantly decreased its activity. Thermal differential scanning calorimetry revealed a slightly higher thermal stability of camel chymosin compared with bovine chymosin. The crystal structure of a doubly glycosylated variant of camel chymosin was determined at a resolution of 1.6?Å and the crystal structure of unglycosylated bovine chymosin was redetermined at a slightly higher resolution (1.8?Å) than previously determined structures. Camel and bovine chymosin share the same overall fold, except for the antiparallel central ?-sheet that connects the N-terminal and C-terminal domains. In bovine chymosin the N-terminus forms one of the strands which is lacking in camel chymosin. This difference leads to an increase in the flexibility of the relative orientation of the two domains in the camel enzyme. Variations in the amino acids delineating the substrate-binding cleft suggest a greater flexibility in the ability to accommodate the substrate in camel chymosin. Both enzymes possess local positively charged patches on their surface that can play a role in interactions with the overall negatively charged C-terminus of ?-casein. Camel chymosin contains two additional positive patches that favour interaction with the substrate. The improved electrostatic interactions arising from variation in the surface charges and the greater malleability both in domain movements and substrate binding contribute to the better milk-clotting activity of camel chymosin towards bovine milk.

  19. Camel and bovine chymosin: the relationship between their structures and cheese-making properties.

    Science.gov (United States)

    Langholm Jensen, Jesper; Mølgaard, Anne; Navarro Poulsen, Jens Christian; Harboe, Marianne Kirsten; Simonsen, Jens Bæk; Lorentzen, Andrea Maria; Hjernø, Karin; van den Brink, Johannes M; Qvist, Karsten Bruun; Larsen, Sine

    2013-05-01

    Bovine and camel chymosin are aspartic peptidases that are used industrially in cheese production. They cleave the Phe105-Met106 bond of the milk protein ?-casein, releasing its predominantly negatively charged C-terminus, which leads to the separation of the milk into curds and whey. Despite having 85% sequence identity, camel chymosin shows a 70% higher milk-clotting activity than bovine chymosin towards bovine milk. The activities, structures, thermal stabilities and glycosylation patterns of bovine and camel chymosin obtained by fermentation in Aspergillus niger have been examined. Different variants of the enzymes were isolated by hydrophobic interaction chromatography and showed variations in their glycosylation, N-terminal sequences and activities. Glycosylation at Asn291 and the loss of the first three residues of camel chymosin significantly decreased its activity. Thermal differential scanning calorimetry revealed a slightly higher thermal stability of camel chymosin compared with bovine chymosin. The crystal structure of a doubly glycosylated variant of camel chymosin was determined at a resolution of 1.6?Å and the crystal structure of unglycosylated bovine chymosin was redetermined at a slightly higher resolution (1.8?Å) than previously determined structures. Camel and bovine chymosin share the same overall fold, except for the antiparallel central ?-sheet that connects the N-terminal and C-terminal domains. In bovine chymosin the N-terminus forms one of the strands which is lacking in camel chymosin. This difference leads to an increase in the flexibility of the relative orientation of the two domains in the camel enzyme. Variations in the amino acids delineating the substrate-binding cleft suggest a greater flexibility in the ability to accommodate the substrate in camel chymosin. Both enzymes possess local positively charged patches on their surface that can play a role in interactions with the overall negatively charged C-terminus of ?-casein. Camel chymosin contains two additional positive patches that favour interaction with the substrate. The improved electrostatic interactions arising from variation in the surface charges and the greater malleability both in domain movements and substrate binding contribute to the better milk-clotting activity of camel chymosin towards bovine milk. PMID:23633601

  20. Density functional theory based quantitative structure-property relationship studies on coumarin-based prodrugs.

    Science.gov (United States)

    Yang, Xinying; Hou, Xuben; Wang, Binghe; Li, Minyong; Fang, Hao

    2012-10-01

    A coumarin-based prodrug system plays a significant role in preparing esterase-sensitive prodrugs of amines and peptides. The electronic structures of 27 coumarin-based prodrugs developed in our lab were calculated at a B3LYP/6-31+G (d,p) level with a Gaussian 03 program. The calculated structural parameters were taken as theoretical descriptors to establish five novel QSPR models. The SMLR linear model (q² = 0.427, r² = 0.516) and the PLS linear model (q² = 0.584, r² = 0.663) were developed with descriptors selected by an Unsupervised Forward Selection method. Another three nonlinear QSPR models were established by a Polynomial Neural Network (PNN) Simulation method (q² = 0.692, 0.675, 0.663; r² = 0.700, 0.688, 0.672). We suggest that the QSPR models derived here, especially the PNN models, can be used to predict the release kinetics of coumarin-based prodrugs as well as design new derivatives of coumarin-based prodrug candidates. PMID:23229116

  1. Syntheses, Local Environments, and Structure-Property Relationships of Solid- State Vanadium Oxide-Fluorides

    Science.gov (United States)

    Donakowski, Martin Daniel

    Understanding the lateral heterogeneity of unconventional plays prior to hydraulic fracturing is important for hydrocarbon production and recovery. Lateral and vertical variability can be affected by composition and textural variation of the rock, which define the rock quality. To characterize the lateral and vertical heterogeneity of rock quality (composition) of the Montney Shale reservoir at Pouce Coupe, Alberta at different scales I conducted a multi-attribute analysis of wells logs integrated with post-stack and pre-stack inversion of a baseline multicomponent seismic survey. Cluster analysis was performed in four wells using the well logs that are most affected by composition. The cluster analysis provides more representative upscale input parameters for reservoir characterization that can be compared with seismic results. The result of this cluster analysis has indicated a lateral variation of composition of the unit C to the east side of the area, where six clusters were chosen and two of them have good petrophysical rock properties that were tied with core data. Post-stack and pre-stack inversions of the baseline of the multicomponent seismic data were performed using constrained sparse spike inversion (CSSI). Pre-stack results shows similar results for the P-impedance, however, there is an improvement in the accuracy of the estimated P-impedance from the pre-stack CSSI (compared to well log P-impedance). The results of P-impedance and S-impedance show the same strong change on the east side of the survey that was detected with the cluster analysis. Crossplots of elastic properties such as Lambda-rho and Mu-rho combined with the results of cluster analysis helped to identify the areas of better rock quality in the 3D seismic. The integration of this heterogeneity analysis with the production profile of the two horizontal wells in the area shows that the lithology has a major influence on the rock quality of the Montney interval. The combined interpretation of this work with an understanding of the natural fracture system and the stress state of the reservoir can provide a rock quality index (RQI). This RQI can aid in future exploration and operational development of the Montney play and other shale reservoirs worldwide.

  2. 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.

  3. The Relationship Satisfaction scale – Psychometric properties

    Directory of Open Access Journals (Sweden)

    Espen Røysamb

    2014-12-01

    Full Text Available The aim of this study was to establish the psychometric properties of the new Relationship Satisfaction (RS scale. Two population based samples were used: The Norwegian Mother and Child Cohort Study (MoBa, N=117,178 and The Quality of Life study (N=347. Convergent and discriminant validity was investigated in relation to the Quality of Marriage Index (QMI, the Satisfaction With Life Scale (SWLS, Relationship Satisfaction of partner, Big Five personality traits (IPIP50 and future relationship dissolution. The full scale with ten items (RS10 and a short version with five items (RS5 showed good psychometric properties. The scale has high internal and test-retest reliability and high structural, convergent, and discriminant validity. Measurement invariance across gender was established. Additionally, predictive validity was evidenced by prediction of future relationship dissolution. We conclude that the RS scale is highly useful as a generic measure of global relationship satisfaction.

  4. Phase transition induced by pressure in TbCrO4 oxide: Relationship structure-properties

    International Nuclear Information System (INIS)

    Terbium chromate TbCrO4, which has been described as belonging to the zircon-type structure showing tetragonal symmetry, space group I41/amd, has been prepared as a dimorphic compound. When the zircon-type TbCrO4 polymorph is treated at 40 kbar and 833 K takes place a phase transition to the tetragonal scheelite-type TbCrO4 polymorph, space group I41/a, with lattice parameters a = 5.0315(10) A and c = 11.3740(2) A. Magnetic susceptibility measurements reveal dramatic changes concerning the magnetic behavior of these two polymorphs. In this sense, the zircon-type TbCrO4 polymorph behaves as ferromagnetic with a Curie temperature of 22 K, while the scheelite-type TbCrO4 polymorph is antiferromagnetic with TN = 29 K. M vs. H plots at different temperatures show the presence of a metamagnetic transition for the scheelite-type TbCrO4 polymorph with a critical field of 2.6 T. The change of the sign of the magnetic interaction has been explained taking into account the differences found in the distances and bond angles of the superexchange Tb-O-Cr pathway through these interactions take place in both zircon and scheelite polymorphs.

  5. Structure-property relationship in aliphatic polyamide/polyaniline surface layered composites

    International Nuclear Information System (INIS)

    Highlights: ? Synthesis of surface conducting polymers based on aliphatic polyamides and polyaniline. ? The study revealed the layered structure of the surface conductive composites. ? Different dielectric relaxation processes were found as a function of doping agent and polyaniline oxidation state. ? Conductivity value (10-4-10-11 S cm-1) enables the use of such composites as antistatic/electrostatic discharge materials. - Abstract: Conducting polymer composite films based on different aliphatic polyamides (PA) (PA-6, PA-11 and PA-12) have been synthesized by in situ aniline polymerization inside a surface layer of the PA host matrix. Dielectric permittivity and dielectric loss of these films are explained in terms of the interfacial polarization. The real part of permittivity is found to be higher in the PA/polyaniline (PANI) composite films than in the virgin PA polymer matrix. Such behaviour is attributed to the interaction between PA and PANI molecular chains and to the conductivity increase after the aniline polymerization. The performed confocal Raman spectrometry and X-ray diffraction studies also confirmed the presence of interactions between PA and PANI molecular chains.

  6. Structure-property relationships of smectic liquid crystalline polyacrylates as revealed by SAXS

    Scientific Electronic Library Online (English)

    Fabiano V., Pereira; Redouane, Borsali; Olga M.S., Ritter; Paulo F., Gonçalves; Aloir A., Merlo; Nadya P. da, Silveira.

    2006-04-01

    Full Text Available A influência da estrutura química dos grupos mesogênicos e do tamanho dos grupos espaçadores, no comportamento de fase de uma série de cristais líquidos poliméricos de cadeia lateral (SCLCP), foram estudados utilizando-se espalhamento de raios-X a Baixo Ângulo (SAXS) e Microscopia Ótica de Luz Polar [...] izada (POM). Análises do arranjo das mesofases em amostras não orientadas e orientadas por ação do campo magnético são descritas. O papel do tamanho do espaçador lateral no empacotamento local e na largura da camada esmética determinados nas mesofases SmA e SmC é elucidado. Os ângulos teta formados entre os grupos mesogênicos e a normal às camadas nas mesofases SmC foram determinados. Um estudo a respeito do grau de ordem em função da temperatura, para os polímeros esméticos foi possível através de medidas de SAXS. Uma ordenação particular em um dos SCLCPs estudados é relacionada com a coexistência de duas fases distintas. Abstract in english The influence of the chemical structure of the mesogenic groups and the length of the spacer groups on the phase behavior in a series of side-chain liquid crystalline polyacrylates (SCLCP) have been studied using Small Angle X-ray Scattering (SAXS) and Polarized Optical Microscopy (POM). Analyses of [...] the mesophase arrangement in unaligned and aligned samples by magnetic field are reported. The role of the spacer length on the local packing and on the thickness of the layers encountered in the SmA and SmC mesophases is elucidated. The tilt angles theta of the mesogenic cores related to the normal of the layers in the SmC mesophases are measured. A study about the degree of order as a function of temperature for the smectic polymers was possible using SAXS measurements. A particular arrangement in one of the studied SCLCPs is related to the coexistence of two different phases.

  7. Structure-property relationship of amplified spontaneous emission in organic semiconductor materials: TPD, DPABP, and NPB.

    Science.gov (United States)

    Wu, Zhaoxin; Ma, Lin; Liu, Peng; Zhou, Caihua; Ning, Shuya; El-Shafei, Ahmed; Zhao, Xiang; Hou, Xun

    2013-10-24

    N,N'-Diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) was demonstrated to be suitable for stimulated emission in doping and nondoping planar waveguide structure, but the mechanism for its lasing is of ambiguity. With the aim of providing a microsscopic picture for its lasing, we performed a combined experimental and theortical investigation of the absorption, photoluminescence (PL), and stimulated emission of TPD and other two similar molecules: 1,4-bis (diphenylamino)biphenyl (DPABP) and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4?-diamine (NPB). It was found that DPABP shows the same amplified spontaneous emission (ASE) characteristics as TPD, but NPB did not. In theory, density functional theory (DFT) and Franck-Condon Principle were used to analyze the molecular geometry in the electronic ground state as well as the optically excited state and the vibrational levels in electronic ground state, respectively. The calculation results show that for TPD and DPABP, several strongly elongated high-frequency modes (1199-1664 cm(-1)) in the carbon rings contribute to the distinct first vibronic sideband in the PL spectra, which form an effective four-level system for lasing. For NPB, when the peripheral toluene or benzene is replaced with naphthyl, a number of strongly elongated low-frequency modes (11-689 cm(-1)) deriving from naphthyl leads to a series of energy sublevels, which destroys the four-level system. Our results provided a new insight and better understanding into the lasing of organic molecules. PMID:24032429

  8. Structure-property relationship of supramolecular ferroelectric [H-66dmbp][Hca] accompanied by high polarization, competing structural phases, and polymorphs.

    Science.gov (United States)

    Kobayashi, Kensuke; Horiuchi, Sachio; Ishibashi, Shoji; Kagawa, Fumitaka; Murakami, Youichi; Kumai, Reiji

    2014-12-22

    Three polymorphic forms of 6,6'-dimethyl-2,2'-bipyridinium chloranilate crystals were characterized to understand the origin of polarization properties and the thermal stability of ferroelectricity. According to the temperature-dependent permittivity, differential scanning calorimetry, and X-ray diffraction, structural phase transitions were found in all polymorphs. Notably, the ferroelectric ?-form crystal, which has the longest hydrogen bond (2.95?Å) among the organic acid/base-type supramolecular ferroelectrics, transformed from a polar structure (space group, P21) into an anti-polar structure (space group, P21/c) at 378?K. The non-ferroelectric ?- and ?-form crystals also exhibited structural rearrangements around hydrogen bonds. The hydrogen-bonded geometry and ferroelectric properties were compared with other supramolecular ferroelectrics. A positive relationship between the phase-transition temperature (TC ) and hydrogen-bond length () was observed, and was attributed to the potential barrier height for proton off-centering or order/disorder phenomena. The optimized spontaneous polarization (Ps ) agreed well with the results of the first-principles calculations, and could be amplified by separating the two equilibrium positions of protons with increasing . These data consistently demonstrated that stretching is a promising way to enhance the polarization performance and thermal stability of hydrogen-bonded organic ferroelectrics. PMID:25363720

  9. Relationships between soil properties and community structure of soil macroinvertebrates in oak-history forests along an acidic deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Kuperman, R.G. [Argonne National Lab., IL (United States). Environmental Assessment Div.

    1996-02-01

    Soil macroinvertebrate communities were studied in ecologically analogous oak-hickory forests across a three-state atmospheric pollution gradient in Illinois, Indiana, and Ohio. The goal was to investigate changes in the community structure of soil fauna in study sites receiving different amounts of acidic deposition for several decades and the possible relationships between these changes and physico-chemical properties of soil. The study revealed significant differences in the numbers of soil animals among the three study sites. The sharply differentiated pattern of soil macroinvertebrate fauna seems closely linked to soil chemistry. Significant correlations of the abundance of soil macroinvertebrates with soil parameters suggest that their populations could have been affected by acidic deposition in the region. Abundance of total soil macroinvertebrates decreased with the increased cumulative loading of acidic deposition. Among the groups most sensitive to deposition were: earthworms gastropods, dipteran larvae, termites, and predatory beetles. The results of the study support the hypothesis that chronic long-term acidic deposition could aversely affect the soil decomposer community which could cause lower organic matter turnover rates leading to an increase in soil organic matter content in high deposition sites.

  10. Predicting the melting points of ionic liquids by the Quantitative Structure Property Relationship method using a topological index

    International Nuclear Information System (INIS)

    Highlights: • A general topological index was proposed based on atom characters and position. • The topological index was extended for predicting melting points of ionic liquids. • A topological index was generated from anion and cation. -- Abstract: A Quantitative Structure Property Relationship (QSPR) model was developed to predict the melting points of ionic liquids (ILs) with diverse classes of cations and anions. The QSPR model was based on the general topological index (TI) proposed in our previous work. The TI was successfully used for the prediction of the decomposition temperature of ILs and the toxicity of ILs in acetylcholine esterase and Leukemia Rat Cell Line. ILs are a class of molten salts which are composed entirely of cations and anions, therefore the descriptors for ILs are generally calculated from cations and anions separately and the interaction between them is neglected. In this study, besides the two sets of TIs generated from cations and anions, a third TI was used to depict the interaction of anions and cations. The QSPR model is on the base of eight kinds of ILs, which are imidazolium, benzimidazolium, pyridinium, pyrrolidinium, ammonium, sulfonium, triazolium and guanidinium. The regression coefficient (R2) and the overall average absolute deviation (AAD) are 0.778 and 7.20%, respectively

  11. Development of an acidity scale for Bronsted acidic ionic liquids and investigation of their structure property relationships

    Science.gov (United States)

    Davuluru, Rajeev

    This work accomplishes three major goals: the novel synthesis of acidic ionic liquids, the design of an acidity scale in non-aqueous medium for these ionic liquids and the elucidation of the structure property relationships of these acidic ionic liquids. Acidity measurements are done by pKa in aqueous media and by relative reactivity of the acidic ionic liquids with diazodiphenylmethane in non-aqueous media. For non-aqueous media the rate of reaction is controlled by the acid strength because the rate limiting step is the proton transfer from the acid to diazodiphenylmethane; this rate is measured via UV-Vis spectroscopy. With increasing electron withdrawing effect, electron density is removed from the nitrogen making the bond between N-H weaker, which increases the acidity in non-aqueous media; however, the opposite is true in aqueous media. For this case the conjugate base is stabilized by intermolecular interactions which are weakened as the electron withdrawing effect increases, decreasing the acidity. Quantum chemistry calculations are used to support this explanation on the substituents effects on the acidity of ionic liquids in aqueous media. Further laboratory experiments are needed to generalize the acidity scale.

  12. Theoretical study of the structure-properties relationship in new class of 2,5-di(2-thienyl)pyrrole compounds

    Science.gov (United States)

    Kart, Sevgi Özdemir; Ebru Tanbo?a, A.; Soyleyici, Hakan Can; Ak, Metin; Kart, Hasan Hüseyin

    2015-02-01

    Detailed studies of the structure-property relationships for conductive polymers are important for the proper understanding of the impact of morphological details on chemical and physical properties. This understanding is necessary for the development of realistic theoretical models. The particular cases of thienyl pyrroles are described. Ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT) calculations with the basis set of 6-31G(d) are performed to determine the molecular structural properties and to calculate FT-IR and NMR spectrum of the title molecule. Moreover, assignments of the vibrational modes are made on the basis of potential energy distribution (PED). Furthermore, the correlations between the observed and calculated frequencies are found to be in good agreement with each other as well as the correlation of the NMR data. A comparison of the experimental and theoretical calculations can be very useful in making correct assignment and understanding the properties and molecular structure relations.

  13. Structural characterization and cytotoxic properties of a 4-O-methylglucuronoxylan from castanea sativa. 2. Evidence of a structure-activity relationship.

    Science.gov (United States)

    Barbat, Aline; Gloaguen, Vincent; Moine, Charlotte; Sainte-Catherine, Odile; Kraemer, Michel; Rogniaux, Hélène; Ropartz, David; Krausz, Pierre

    2008-08-01

    Xylans were purified from delignified holocellulose alkaline extracts of Castanea sativa (Spanish chestnut) and Argania spinosa (Argan tree) and their structures analyzed by means of GC of their per-trimethylsilylated methylglycoside derivatives and (1)H NMR spectroscopy. The structures deduced were characteristic of a 4-O-methylglucuronoxylan (MGX) and a homoxylan (HX), respectively, with degrees of polymerization ranging from 182 to 360. In the case of MGX, the regular or random distribution of 4-O-methylglucuronic acid along the xylosyl backbone--determined by MALDI mass spectrometry after autohydrolysis of the polysaccharide--varied and depended both on the botanical source from which they were extracted and on the xylan extraction procedure. The MGX also inhibited in different ways the proliferation as well as the migration and invasion capability of A431 human epidermoid carcinoma cells. These biological properties could be correlated with structural features including values of the degree of polymerization, 4-O-MeGlcA to xylose ratios, and distribution of 4-O-MeGlcA along the xylosyl backbone, giving evidence of a defined structure-activity relationship. PMID:18646856

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

    OpenAIRE

    Yang, S. Y.; Liu, L.; Z. X. Jia; W. W. Fu; D. M. Jia; Y. F. Luo

    2014-01-01

    Vulcanization property and structure-properties relationship of natural rubber (NR)/silica (SiO2) composites modified by a novel multi-functional rubber agent, N-phenyl- N'-(?-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 ...

  15. Investigating structure-property relationships in cathode materials via combined ex-situ and in-situ diffraction techniques

    International Nuclear Information System (INIS)

    While anode and electrolyte materials continue to see significant advances, cathode materials remain underdeveloped in comparison. As a battery's performance is determined by its weakest component further improvements to cathode materials are essential. Given the complex chemical and structural changes which can take place in cathode materials on cycling, a range of advanced characterization techniques must be utilised in order to understand the properties well enough to then improve upon them. A combination and ex-situ type dialyses has been performed on the cathode material Li0.18Sr0.66Ti0.5BNb0.5O3. Ex-situ neutron diffraction experiments, following the chemical insertion of lithium enabled the location of lithium within the structure to be accurately determined through Rietveld refinement and calculation of Fourier difference maps. More significantly, the evolution of phases and structural change in this material has been followed utilizing both in-situ neutron and synchrotron diffraction experiments. Sequential Rietveld refinements have allowed the change in structure to be directly correlated with the observed electrochemical properties. Specifically, due to the real time collection of structure; data as a function of discharge. the rate of structural change was measured and directly correlated with electrochemical portfolio. This contribution will demonstrate how a combination of ex-situ diffraction of chemical and electrochemical insertion of lithium as well as in-situ diffraction of electrochemical insertion of lithium can provide a robust picture of how the structure influences properties.

  16. Propriedades químico-quânticas empregadas em estudos das relações estrutura-atividade / Quantum chemical properties used in structure-activity relationship studies

    Scientific Electronic Library Online (English)

    Agnaldo, Arroio; Káthia M., Honório; Albérico B. F. da, Silva.

    Full Text Available [...] Abstract in english In this work we show that structure-activity relationship studies are of great importance in modern chemistry and biochemistry. In order to obtain a significant correlation, it is crucial that appropriate descriptors be employed. Thus, quantum chemical calculations are an attractive source of new mo [...] lecular descriptors which can, in principle, express all the electronic and geometric properties of molecules and their interactions with the biological receptor.

  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'-(?-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. Study of the structure-properties-processing relationship of nanocomposites based on poly (lactic acid) (PLA) and o-MMT

    International Nuclear Information System (INIS)

    In this work, the effect of processing and nanoclay content on the mechanical properties of thin sheets obtained by cast sheet extrusion from a commercial grade of PLA and organomodified nanoclay has been investigated. Microstructure was studied using Transmission Electron Microscopy (TEM) and Wide Angle X-ray Scattering (WAXS), revealing the development of structures intercalated, although exfoliated clay layers and agglomerates were observed also. The mechanical properties have been assessed by uniaxial tensile tests. Finally, a deaging thermal treatment was applied to all prepared samples, in order to study the materials under two different states: relaxed (after the thermal treatment) and aged (before treatment). The tensile behaviour is affected by processing only in the case of aged PLA samples, whereas the addition of nanoclay is only significant at 2,5 % w/w. The de-aging treatment causes a change in the brittle-ductile behaviour evidenced in a significant increase in ductilily

  19. Binding properties and structure-affinity relationships of food antioxidant butylated hydroxyanisole and its metabolites with lysozyme.

    Science.gov (United States)

    Wu, Di; Yan, Jin; Tang, Peixiao; Li, Shanshan; Xu, Kailin; Li, Hui

    2015-12-01

    Considering the harmful impact of food antioxidants on human bodies, thoroughly exposing their potential effects at the molecular level is important. In this study, the binding interactions of butylated hydroxyanisole (BHA), a phenolic antioxidant, and its different major metabolites tert-butylhydroquinone (TBHQ) and tert-butylbenzoquinone (TBQ) with lysozyme were examined via fluorescence, three-dimensional fluorescence, circular dichroism (CD), and ligand-protein docking studies. The three compounds caused strong quenching of lysozyme fluorescence by a static quenching mechanism but with different quenching efficiencies and different effects on the ?-helix content of the lysozyme. The order of binding affinity of lysozyme for all test compounds is as follows: BHA>TBQ>TBHQ. Thermodynamic parameters indicated that hydrogen bonding and van der Waals forces perform dominant functions in the binding between these compounds and lysozyme. Furthermore, structure-affinity relationships between the model compounds and lysozyme were established on the basis of computational analyses. PMID:26041206

  20. The relationship between chemical structure and dielectric properties of plasma-enhanced chemical vapor deposited polymer thin films

    International Nuclear Information System (INIS)

    Polymer dielectric films fabricated by plasma enhanced chemical vapor deposition (PECVD) have unique properties due to their dense crosslinked bulk structure. These spatially uniform films exhibit good adhesion to a variety of substrates, excellent chemical inertness, high thermal resistance, and are formed from an inexpensive, solvent-free, room temperature process. In this work, we studied the dielectric properties of plasma polymerized (PP) carbon-based polymer thin films prepared from two precursors, benzene and octafluorocyclobutane. Two different monomer feed locations, directly in the plasma zone or in the downstream region (DS) and two different pressures, 80 Pa (high pressure) or 6.7 Pa (low pressure), were used. The chemical structure of the PECVD films was examined by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The dielectric constant (? r) and dielectric loss (tan ?) of the films were investigated over a range of frequencies up to 1 MHz and the dielectric strength (breakdown voltage) (F b) was characterized by the current-voltage method. Spectroscopic ellipsometry was performed to determine the film thickness and refractive index. Good dielectric properties were exhibited, as PP-benzene films formed in the high pressure, DS region showed a Fb of 610 V/?m, an ? r of 3.07, and a tan ? of 7.0 x 10-3 at 1 kHz. The PECVD processing pressure has a significant effect on pressure has a significant effect on final film structure and the film's physical density has a strong impact on dielectric breakdown strength. Also noted was that the residual oxygen content in the PP-benzene films significantly affected the frequency dependences of the dielectric constant and loss

  1. Structure property relationships in the ATi2O4 (A=Na, Ca) family of reduced titanates

    International Nuclear Information System (INIS)

    Reduced titanates in the ATi2O4 (A=Li, Mg) spinel family exhibit a variety of interesting electronic and magnetic properties, most notably superconductivity in the mixed-valence spinel, Li1+ x Ti2- x O4. The sodium and calcium analogs, NaTi2O4 and CaTi2O4, each differ in structure, the main features of which are double rutile-type chains composed of edge-sharing TiO6 octahedra. We report for the first time, the properties and band structures of these two materials. XANES spectroscopy at the Ti K-edge was used to probe the titanium valence. The absorption edge position and the pre-edge spectral features observed in the XANES data confirm the assignment of Ti3+ in CaTi2O4 and mixed-valence Ti3+/Ti4+ in NaTi2O4. Temperature-dependent resistivity and magnetic susceptibility studies are consistent with the classification of both NaTi2O4 and CaTi2O4 as small band-gap semiconductors, although changes in the high-temperature magnetic susceptibility of CaTi2O4 suggest a possible insulator-metal transition near 700 K. Band structure calculations agree with the observed electronic properties of these materials and indicate that while Ti-Ti bonding is of minimal importance in NaTi2O4, theance in NaTi2O4, the titanium atoms in CaTi2O4 are weakly dimerized at room temperature. -- Graphical abstract: Normalized titanium K-edge XANES spectra confirm mixed-valence for NaTi2O4 with an edge energy intermediate between Ti3+ oxides such as CaTi2O4, MgTi2O4 and Ti2O3, and Ti4+ containing oxides such as TiO2

  2. Structure-property relationships: asymmetric alkylphenyl-substituted anthracene molecules for use in small-molecule solar cells.

    Science.gov (United States)

    Kim, Yu Jin; Ahn, Eun Soo; Jang, Sang Hun; An, Tae Kyu; Kwon, Soon-Ki; Chung, Dae Sung; Kim, Yun-Hi; Park, Chan Eon

    2015-05-11

    Two asymmetric anthracene-based organic molecules, NDHPEA and TNDHPEA, were prepared without or with a thiophene spacer between the anthracene and naphthalene units. These asymmetric oligomers displayed different degrees of coplanarity, as evidenced by differences in the dihedral angles calculated by using DFT. Differential scanning calorimetry and XRD studies were used to probe the crystallization characteristics and molecular packing structures in the active layers. The coplanarity of the molecules in the asymmetric structure significantly affected the crystallization behavior and the formation of crystalline domains in the solid state. The small-molecule crystalline properties were correlated with the device physics by determining the J-V characteristics and hole mobilities of the devices. PMID:25711202

  3. Predicting equilibrium vapour pressure isotope effects by using artificial neural networks or multi-linear regression - A quantitative structure property relationship approach.

    Science.gov (United States)

    Parinet, Julien; Julien, Maxime; Nun, Pierrick; Robins, Richard J; Remaud, Gerald; Höhener, Patrick

    2015-09-01

    We aim at predicting the effect of structure and isotopic substitutions on the equilibrium vapour pressure isotope effect of various organic compounds (alcohols, acids, alkanes, alkenes and aromatics) at intermediate temperatures. We attempt to explore quantitative structure property relationships by using artificial neural networks (ANN); the multi-layer perceptron (MLP) and compare the performances of it with multi-linear regression (MLR). These approaches are based on the relationship between the molecular structure (organic chain, polar functions, type of functions, type of isotope involved) of the organic compounds, and their equilibrium vapour pressure. A data set of 130 equilibrium vapour pressure isotope effects was used: 112 were used in the training set and the remaining 18 were used for the test/validation dataset. Two sets of descriptors were tested, a set with all the descriptors: number of(12)C, (13)C, (16)O, (18)O, (1)H, (2)H, OH functions, OD functions, CO functions, Connolly Solvent Accessible Surface Area (CSA) and temperature and a reduced set of descriptors. The dependent variable (the output) is the natural logarithm of the ratios of vapour pressures (ln R), expressed as light/heavy as in classical literature. Since the database is rather small, the leave-one-out procedure was used to validate both models. Considering higher determination coefficients and lower error values, it is concluded that the multi-layer perceptron provided better results compared to multi-linear regression. The stepwise regression procedure is a useful tool to reduce the number of descriptors. To our knowledge, a Quantitative Structure Property Relationship (QSPR) approach for isotopic studies is novel. PMID:25559176

  4. Structure-Processing-Property Relationships at the Fiber-Matrix Interface in Electron-Beam Cured Composite Materials

    Energy Technology Data Exchange (ETDEWEB)

    Janke, C.J.

    1998-11-01

    The objective of this project was to characterize the properties of the resin and the fiber- resin interface in electron beam cured materials by evaluating several structural and processing parameters. The Oak Ridge National Laboratory (ORNL) has recently determined that the interlaminar shear strength properties of electron beam cured composites were 19-28% lower than for autoclave cured composites. Low interlaminar shear strength is widely acknowledged as the key barrier to the successfid acceptance and implementation of electron beam cured composites in industry. In this project we found that simple resin modification and process improvements are unlikely to substantially improve the interlaminar shear strength properties of electron beam cured composites. However, sizings and coatings were shown to improve these properties and there appears to be significant potential for further improvement. In this work we determined that the application of epoxy-based, electron beam compatible sizings or coatings onto surface- treated, unsized carbon fibers improved the composite interlaminar shear strength by as much as 55% compared to composites fabricated from surface-treated, unsized carbon fibers and 11 YO compared to composites made from surface-treated, GP sized carbon fibers. This work has identified many promising pathways for increasing the interlaminar shear strength of electron beam cured composites. As a result of these promising developments we have recently submitted a U.S. Department of Energy-Energy Research (DOE-ER) sponsored Laboratory Technical Research-Cooperative Research and Development Agreement (LTR- CRADA) proposal entitled, "Interracial Properties of Electron Beam Cured Composites", to continue this work. If funded, ORNL will lead a 3-year, $2.6 million effort involving eight industrial partners, NASA-Langley, and the U.S. Air Force. The principal objective of this CRADA is to significantly improve the interracial properties of carbon-fiber-reinforced composites beyond the current state-of-the art electron beam cured composites for use in several DOE, DoD, and industrial applications. In addition, several papers from this Laboratory Director's Research and Development (LDRD) project will be submitted to the Society for the Advancement of Materials and Process Engineering for oral presentations and publications.

  5. Ionic conduction, bond valence analysis of structure–property relationships of NaHoP2O7

    International Nuclear Information System (INIS)

    Single crystals of NaHoP2O7 diphosphate have been prepared by the flux method and its structural and physical properties have been investigated. It crystallizes in the monoclinic system with the space group P21/n and its parameters are: a=8.6796(4) Å, b=5.3677(2) Å, c=13.6904(6) Å, ?=106.120° (2), V=612.75 (5) Å3, Z=4. The structure of NaHoP2O7 consists of a three-dimensional framework of HoO6 octahedra, linked by P2O7 diphosphate units, forming tunnels running parallel to [0 1 0], which are occupied by Na atoms. The infrared and Raman vibrational spectra have been investigated. Activation energy was obtained from Arrhenius plots (Ln ?T versus 1000/T) and found to be 1.27 eV. The coupling of the structural analysis with the BVS model for NaHoP2O7 has better interpret the measurements of the ionic conductivity and the most probably transport pathway model was determined. - Graphical abstract: Schematic representation of the structural arrangement of NaHoP2O7 shows the sodium conduction pathway along the [0 1 0] direction. Highlights: • Single crystals of NaHoP2O7 were prepared by flux method and characterized by single-crystal X-ray data. • The conductivity and loss spectra were analysed in order explain the mechanism of conduction. • The most probably conduction pathway are determined

  6. Structure-Property-Performance Relationships for Organic Photovoltaics and the Utilization of Photoconducting Atomic Force Microscopy for Characterizing Organic Thin Films

    Science.gov (United States)

    Guide, Michele Elyse

    Progress in the development of organic photovoltaics (OPVs) depends on a continually growing understanding of the effects of chemical composition or processing method on the optoelectronic and structural properties and, in turn, how those properties influence device performance. Unfortunately, no single characterization method can provide all of the necessary information to develop these structure-property-performance relationships. This thesis details examples of structure-property-performance studies in which multiple characterization methods are used to identify the root cause of limited device performance for a particular photovoltaic system. As a large part of this work, the refinement and utilization of a nanoscale characterization technique, namely photoconducting atomic force microscopy (pc-AFM) is presented, not as an alternative to other characterization methods, but as a unique approach to characterizing the nanoscale morphology and local optoelectronic properties of an organic thin film simultaneously. The goal of this work was to make pc-AFM as robust and reliable a characterization tool and as close an analog to bulk OPV performance testing as possible. The first sections of this thesis focus on the development of pc-AFM for the characterization of OPVs. The capabilities of pc-AFM at the time this research commenced are illustrated in a study of a multilayered p/i/n architecture OPV system comprising a thermoset small molecule donor, tetrabenzoporphyrin (BP) and one of two structurally similar soluble fullerene derivative acceptors. By investigating the nanoscale topography, dark current, and photocurrent in each layer of these multilayer devices, the differences in bulk device performance can be rationalized and the composition of specific morphological features can be identified. At the same time, this study demonstrates how interpretation of pc-AFM measurements was not straightforward and required knowledge of the bulk performance. This issue prompted efforts to improve the technique to increase reliability and applicability to OPVs. Subsequently, sensitivity studies of the experimental parameters such as contact force, illumination intensity and spot size, and film processing conditions were performed, further elucidating factors that must be taken into consideration when designing and interpreting a pc-AFM experiment. In order to better control and monitor the environmental conditions during a pc-AFM experiment, a custom glovebox was designed to house and interface with the pc-AFM. Realization of this glovebox allowed further improvements in reliability of pc-AFM measurements and enabled the use of low workfunction AFM probes that better mimic the low workfunction top electrode typically employed in bulk OPVs. The initial use of BP as a donor material in pc-AFM measurements led to the utilization of BP in other OPV systems due to its rare properties as a solution-processable, thermoset, small molecule electron donor. The latter sections of this thesis describe two structure-property-performance relationship studies utilizing BP as a donor material. In the first study, the use of BP enables the facile testing of solution processable bilayer OPV devices with perylene-based acceptors as alternatives to solubilized fullerene derivatives. The second study compares the optoelectronic and performance characteristics of BP to a Cu-metalized derivative, CuBP, which, despite the promise of this material due to its high charge carrier mobility measured in FETs, performs poorly in OPV devices. Altogether, this work demonstrates the importance of developing structure-property-performance relationships, provides insight to the continued improvement of OPV performance, and sets the groundwork for the reliable utilization of pc-AFM as a technique for characterizing organic thin films.

  7. Quantitative structure-property relationship study of n-octanol-water partition coefficients of some of diverse drugs using multiple linear regression

    International Nuclear Information System (INIS)

    A quantitative structure-property relationship (QSPR) study was performed to develop models those relate the structures of 150 drug organic compounds to their n-octanol-water partition coefficients (log Po/w). Molecular descriptors derived solely from 3D structures of the molecular drugs. A genetic algorithm was also applied as a variable selection tool in QSPR analysis. The models were constructed using 110 molecules as training set, and predictive ability tested using 40 compounds. Modeling of log Po/w of these compounds as a function of the theoretically derived descriptors was established by multiple linear regression (MLR). Four descriptors for these compounds molecular volume (MV) (geometrical), hydrophilic-lipophilic balance (HLB) (constitutional), hydrogen bond forming ability (HB) (electronic) and polar surface area (PSA) (electrostatic) are taken as inputs for the model. The use of descriptors calculated only from molecular structure eliminates the need for experimental determination of properties for use in the correlation and allows for the estimation of log Po/w for molecules not yet synthesized. Application of the developed model to a testing set of 40 drug organic compounds demonstrates that the model is reliable with good predictive accuracy and simple formulation. The prediction results are in good agreement with the experimental value. The root mean square error of prediction (RMSEP) and square correlation coefficient(RMSEP) and square correlation coefficient (R2) for MLR model were 0.22 and 0.99 for the prediction set log Po/w

  8. 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.

  9. Blood-brain barrier permeable anticholinesterase aurones: synthesis, structure-activity relationship, and drug-like properties.

    Science.gov (United States)

    Liew, Kok-Fui; Chan, Kit-Lam; Lee, Chong-Yew

    2015-04-13

    A series of novel aurones bearing amine and carbamate functionalities at various positions (rings A and/or B) of the scaffold was synthesized and evaluated for their acetylcholinesterase and butyrylcholinesterase inhibitory activities. Structure-activity relationship study disclosed several potent submicromolar acetylcholinesterase inhibitors (AChEIs) particularly aurones bearing piperidine and pyrrolidine moieties at ring A or ring B. Bulky groups particularly methoxyls, and carbamate to a lesser extent, at either rings were also prominently featured in these AChEI aurones as exemplified by the trimethoxyaurone 4-3. The active aurones exhibited a lower butyrylcholinesterase inhibition. A 3'-chloroaurone 6-3 originally designed to improve the metabolic stability of the scaffold was the most potent of the series. Molecular docking simulations showed these AChEI aurones to adopt favourable binding modes within the active site gorge of the Torpedo californica AChE (TcAChE) including an unusual chlorine-? interaction by the chlorine of 6-3 to establish additional bondings to hydrophobic residues of TcAChE. Evaluation of the potent aurones for their blood-brain barrier (BBB) permeability and metabolic stability using PAMPA-BBB assay and in vitro rat liver microsomes (RLM) identified 4-3 as an aurone with an optimal combination of high passive BBB permeability and moderate CYP450 metabolic stability. LC-MS identification of a mono-hydroxylated metabolite found in the RLM incubation of 4-3 provided an impetus for further improvement of the compound. Thus, 4-3, discovered within this present series is a promising, drug-like lead for the development of the aurones as potential multipotent agents for Alzheimer's disease. PMID:25768702

  10. Derivation of structure-activity relationships from the anticancer properties of ruthenium(II) arene complexes with 2-aryldiazole ligands.

    Science.gov (United States)

    Martínez-Alonso, Marta; Busto, Natalia; Jalón, Félix A; Manzano, Blanca R; Leal, José M; Rodríguez, Ana M; García, Begoña; Espino, Gustavo

    2014-10-20

    The ligands 2-pyridin-2-yl-1H-benzimidazole (HL(1)), 1-methyl-2-pyridin-2-ylbenzimidazole (HL(2)), and 2-(1H-imidazol-2-yl)pyridine (HL(3)) and the proligand 2-phenyl-1H-benzimidazole (HL(4)) have been used to prepare five different types of new ruthenium(II) arene compounds: (i) monocationic complexes with the general formula [(?(6)-arene)RuCl(?(2)-N,N-HL)]Y [HL = HL(1), HL(2), or HL(3); Y = Cl or BF4; arene = 2-phenoxyethanol (phoxet), benzene (bz), or p-cymene (p-cym)]; (ii) dicationic aqua complexes of the formula [(?(6)-arene)Ru(OH2)(?(2)-N,N-HL(1))](Y)2 (Y = Cl or TfO; arene = phoxet, bz, or p-cym); (iii) the nucleobase derivative [(?(6)-arene)Ru(9-MeG)(?(2)-N,N-HL(1))](PF6)2 (9-MeG = 9-methylguanine); (iv) neutral complexes consistent with the formulation [(?(6)-arene)RuCl(?(2)-N,N-L(1))] (arene = bz or p-cym); (v) the neutral cyclometalated complex [(?(6)-p-cym)RuCl(?(2)-N,C-L(4))]. The cytototoxic activity of the new ruthenium(II) arene compounds has been evaluated in several cell lines (MCR-5, MCF-7, A2780, and A2780cis) in order to establish structure-activity relationships. Three of the compounds with the general formula [(?(6)-arene)RuCl(?(2)-N,N-HL(1))]Cl differing in the arene moiety have been studied in depth in terms of thermodynamic dissociation constants, aquation kinetic constants, and DNA binding measurements. The biologically most active compound is the p-cym derivative, which strongly destabilizes the DNA double helix, whereas those with bz and phoxet have only a small effect on the stability of the DNA double helix. Moreover, the inhibitory activity of several compounds toward CDK1 has also been evaluated. The DNA binding ability of some of the studied compounds and their CDK1 inhibitory effect suggest a multitarget mechanism for their biological activity. PMID:25302401

  11. Fundamental structure-property relationships towards engineering of an integrated NP0 capacitor for bismuth pyrochlore systems

    Science.gov (United States)

    Nino, Juan C.

    A comprehensive investigation of the processing-structure-property-performance (PSPP) interrelationship in the Bi2O3-ZnO-Nb2O 5 (BZN) pyrochlore system towards engineering of an integrated NP0 capacitor with silver electrodes for LTCC (low temperature cofire ceramics) microwave applications is presented. Using the BZN system as a model several specific areas or research are investigated and then correlated to obtain a global understanding of the PSPP interrelationship governing Bi-based pyrochlores. The first area of investigation covers the phase formation for the cubic pyrochlore with nominal composition Bi3/2ZnNb3/2O 7 and monoclinic zirconolite Bi2Zn2/3Nb4/3 O7 compounds through XRD (X-ray diffraction) phase analysis. Formation reactions sequences are identified. In both phases, BNbO4 is found to be a precursor reacting primarily with ZnO. It is also found that in order to kinetically limit the residual BiNbO4, the calcination and sintering profiles should spend limited time at temperatures between 650°C and 750°C. It is shown that high ZnO activity is essential for the phase formation process and therefore the process is extremely dependent on milling and mixing. In addition, alternative processing routes are studied to ensure phase purity. Batching with excess ZnO and low pO2 processing atmospheres are demonstrated as successful options to reduce residual BiNbO4. The solubility of the main BZN phases to ZnO is investigated revealing a wide compositional windows resulting in single phase ceramic. These results serve as a guide for the appropriate modifications in batching and processing required to obtain a BZN composite ceramic exhibiting desirable NP0 characteristics (temperature coefficient of capacitance (TCC) ˜15 ppm/°C, mean dielectric constant of 96 and dielectric loss ˜0.001 at 1 MHz), which can be densified at 950°C with no sintering additives. The second area covers the phase refinement of the main phases in the Bi2O3ZnO-Nb2O5 pyrochlore system performed via detailed XRD, Neutron Diffraction (ND) and Transmission Electron Microscopy (TEM). Essential and unique features in this phase are revealed by ND analysis like the sheet like structure based on HTB- (hexagonal tungsten bronze) like layers formed by [Nb(Zn)O6] octahedra and stacked along the c-axis. (Abstract shortened by UMI.)

  12. Quantitative structure-property relationship studies for collision cross sections of 579 singly protonated peptides based on a novel descriptor as molecular graph fingerprint (MoGF)

    International Nuclear Information System (INIS)

    Aiming at ion mobility spectrometry (IMS), computer-assisted ion mobility prediction (CAIMP) has been recently developed to simulate and predict diverse IMS behaviors in assistance of mathematics and computer science. Of that, quantitative structure-property relationship (QSPR) plays a vital role, dedicating to predict properties of unknown samples by creating statistical model based on known samples. In QSPR, the key lies in how to transform structural characteristics of target compounds into a group of numerical codes. In consideration that future IMS applications may mainly focus on intricate drug/biological systems, a novel molecular structural characterization method referring to molecular graphic fingerprint (MoGF) is proposed in this paper. In MoGF approach, radical distribution function is employed to map intrinsic interatomic correlations into a coordinate system according to a reasonable sampling interval, thus forming the characteristic graph curve which is rich in information on molecular structural characteristics, possessing of great merits in easy calculation, independent of experiments, large information contents, explicit structural meanings and intuitive expressions, etc. Consequently, MoGF is utilized to QSPR studies on 579 singly protonated peptide collision cross sections, and the constructed partial least square (PLS) regression model is confirmed to be robust and predictable by rigorous both internal and external validations, with statistics as external validations, with statistics as r2 = 0.991, q2 = 0.990, RMSEE = 5.526, RMSCV = 5.572, qext2=0.990, rext2=0.990, r0,ext2=0.990, r0,ext'2=0.990, k = 1.003, k' = 0.996 and RMSEP = 5.561, respectively

  13. Elucidating the structure-property relationships of donor-?-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-?-acceptor dye library by a one-pot procedure, evaluation of PCEs, and elucidation of structure-property relationships. No obvious correlations between ?, and the ? were observed, whereas the HOMO and LUMO levels of the dyes were critical for ?. 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, ?, and acceptor blocks. Combinatorial synthesis and evaluation was important for identifying the best dye. PMID:24954633

  14. Quantitative Structure Pharmacokinetic Relationship Using Artificial Neural Network: A Review

    Directory of Open Access Journals (Sweden)

    S. K. Singh

    2009-10-01

    Full Text Available Quantitative structure activity relationship (QSAR has become a tool for designing in various areas like drugs, food additive, Pesticides, biochemical reactant, environmental pollutant and toxic products. In QSAR biological activity can be related with physicochemical properties and in QSPkR (Quantitative Structure Pharmacokinetic Relationship, pharmacokinetic properties can be related with physicochemical properties, relation found in terms of quantity. A number of literature and review article have been published on Quantitative structure pharmacokinetic relationship. But prediction of human pharmacokinetic properties of known and unknown is much difficult job in pharmaceutical industry. Pharmacokinetic data of animal cannot be put straightforward. Artificial neural network (ANN is used to predict the pharmacokinetic properties. Artificial neural network has basic structure like biological brain and compose of neurons which are interconnected to each other. The present review not only compiles the literature of QSPkR using ANN, but gives detail about the physicochemical properties and artificial neural network.

  15. 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

    2015-04-24

    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 activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the 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. PMID:25874741

  16. Quantitative determination of the structure-property relationships in nuclear fuel element materials. Final report, June 1969--July 1973

    International Nuclear Information System (INIS)

    New developments in quantitative microscopy are first described. The use of the described techniques to quantitatively characterize the microstructural states of nickel and uranium dioxide samples is then discussed. The determination of gas permeability, thermal conductivity, mechanical properties, and creep behavior in the characterized samples are also described. (U.S.)

  17. Radiopharmaceuticals: structure-activity relationship

    International Nuclear Information System (INIS)

    A collection of papers presented at a symposium held in Hartford Connecticut, March 21-23, 1980 is presented. The aim of the book is to review the influence of chemical structure on the biological distribution of radioactively labeled compounds with a view towards proposing a rational approach to the design of future radiopharmaceuticals. The material covers most of the known work that has been completed in this area. The book contains 38 chapters with 1,415 references arranged in five major sections: a) basic aspects of structure-activity relationship; b) metals and organometallic compounds; c) lipid soluble materials; d) analysis of structure-activity in major organs, and e) cyclotron-produced radionuclides, nutrients, and analogues. Each section can be read independent of the others

  18. Ordered Structures and Thermoelectric Properties of MNiSn (M = Ti, Zr, Hf)-Based Half-Heusler Compounds Affected by Close Relationship with Heusler Compounds

    Science.gov (United States)

    Kimura, Yoshisato; Chai, Yaw-Wang

    2015-01-01

    Half-Heusler compounds are excellent thermoelectric materials. A characteristic of the half-Heusler-type ordered structure is the vacancy site that occupies one-fourth of all the lattice points. Therefore, a half-Heusler ABX phase (where A and B are typically transition metal elements, such as Ti, Zr, and Hf, and X represents a half-metal element such as Sn or Sb) has a crystallographically close relationship with a Heusler AB2X phase in the sense that the vacancy site in the half-Heusler phase is filled with B atoms in the Heusler phase. The thermoelectric properties are improved or affected by point lattice defects related to the vacancy site and the B site, such as the antisite atom B in the vacancy site, vacancies in the B site, and vacancy-site occupancy by quaternary C atoms. A modulated-like nanostructure due to point defects regarding vacancies and Ni atoms is formed for an instance in ZrNiSn alloys even close to the stoichiometric composition. Ni-rich nanoclusters are locally formed by excessive Ni antisite atoms in the vacancy site, which work as precursors of Heusler precipitates (TiNi2Sn, ZrNi2Sn, and so forth). The vacancy-site occupation in ZrNiSn with Co and Ir results in the drastic conversion of thermoelectric properties from n type to p type, and the effective reduction of the lattice thermal conductivity.

  19. Crystal structure of hyperthermophilic esterase EstE1 and the relationship between its dimerization and thermostability properties

    Directory of Open Access Journals (Sweden)

    Koh Eunhee

    2007-07-01

    Full Text Available Abstract Background EstE1 is a hyperthermophilic esterase belonging to the hormone-sensitive lipase family and was originally isolated by functional screening of a metagenomic library constructed from a thermal environmental sample. Dimers and oligomers may have been evolutionally selected in thermophiles because intersubunit interactions can confer thermostability on the proteins. The molecular mechanisms of thermostabilization of this extremely thermostable esterase are not well understood due to the lack of structural information. Results Here we report for the first time the 2.1-Å resolution crystal structure of EstE1. The three-dimensional structure of EstE1 exhibits a classic ?/? hydrolase fold with a central parallel-stranded beta sheet surrounded by alpha helices on both sides. The residues Ser154, Asp251, and His281 form the catalytic triad motif commonly found in other ?/? hydrolases. EstE1 exists as a dimer that is formed by hydrophobic interactions and salt bridges. Circular dichroism spectroscopy and heat inactivation kinetic analysis of EstE1 mutants, which were generated by structure-based site-directed mutagenesis of amino acid residues participating in EstE1 dimerization, revealed that hydrophobic interactions through Val274 and Phe276 on the ?8 strand of each monomer play a major role in the dimerization of EstE1. In contrast, the intermolecular salt bridges contribute less significantly to the dimerization and thermostability of EstE1. Conclusion Our results suggest that intermolecular hydrophobic interactions are essential for the hyperthermostability of EstE1. The molecular mechanism that allows EstE1 to endure high temperature will provide guideline for rational design of a thermostable esterase/lipase using the lipolytic enzymes showing structural similarity to EstE1.

  20. Self-organised nanocomposites from porous silicon. Evidence of the relationship between nano-scale structure and its electronic properties

    International Nuclear Information System (INIS)

    The composition study of the oxidized PS layer after Al-film coating has been shown by STM, STS (with tunnel I-V curves) and IR-spectroscopy to be the self-organized Si nanocrystallite. SixOy:SizOyAl or Si-nanocrystallite: SixOy nanocomposites. The electronic properties (tunnel current, capacity, differential capacity relaxation) are determined by the presence of Si-nanocrystallites with size of 2,5-4 nm, and band gap E=2,4-2,8 eV surrounded by the matrix consisting of SiO, SiO2, Si2O3 and SixOyAl nanooxides. (author)

  1. Validating the German Version of the Quality of Relationship Inventory: Confirming the Three-Factor Structure and Report of Psychometric Properties

    Science.gov (United States)

    Reiner, Iris; Beutel, Manfred; Skaletz, Christian; Brähler, Elmar; Stöbel-Richter, Yve

    2012-01-01

    Research on psychosocial influences such as relationship characteristics has received increased attention in the clinical as well as social-psychological field. Several studies demonstrated that the quality of relationships, in particular with respect to the perceived support within intimate relationships, profoundly affects individuals' mental and physical health. There is, however, a limited choice of valid and internationally known assessments of relationship quality in Germany. We report the validation of the German version of the Quality of Relationships Inventory (QRI). First, we evaluated its factor structure in a representative German sample of 1.494 participants by means of confirmatory factor analysis. Our findings support the previously proposed three-factor structure. Second, importance and satisfaction with different relationship domains (family/children and relationship/sexuality) were linked with the QRI scales, demonstrating high construct validity. Finally, we report sex and age differences regarding the perceived relationship support, conflict and depth in our German sample. In conclusion, the QRI is a reliable and valid measurement to assess social support in romantic relationships in the German population. PMID:22662151

  2. Investigation of the structure/property relationship of spray-formed 7XXX series high-strength aluminum alloys and their metal matrix composites

    Science.gov (United States)

    Sharma-Judd, Malavika M.

    2000-12-01

    The purpose of this investigation was to identify the structure/property relationship of spray formed 7XXX series alloys. High solute, ultra-high strength 7XXX series aluminum alloys with solute contents close to equilibrium solid solubility limits of the Al-Zn-Mg-Cu system have been produced by rapid solidification using spray deposition. The process yields massive preforms directly from the liquid state. Various elements, including chromium, manganese, silver, zirconium and scandium, were incorporated to produce a variety of microstructures and mechanical properties. SiC particulate was added to these same alloy compositions to produce metal matrix composites (MMCs). The resulting extruded products in the T6 and T7 conditions were evaluated and compared. Under peak-aged conditions in the unreinforced materials, strengths in excess of 860 MPa were achieved, with one alloy exceeding 900 MPa. Apart from the elongation to failure, the mechanical properties of the composite materials were equal to or superior to those of their unreinforced counterparts. The superior strength properties of the spray formed alloys were attributed to two major substructures with different scale; nanometer sized eta ' metastable precipitates and slightly larger, but finely distributed dispersoids. The large volume fraction of plate-like eta' precipitates (average size 58A, ranging up to 73 A in diameter) were identified as having a hexagonal structure with lattice parameters a = 0.488 nm and c = 1.376. The remarkable strengthening is predominantly attributed to precipitation hardening. The enhanced mechanical properties of the MMC materials are attributed to the increased dislocation density, and thus, a higher concentration of structural particles compared to the unreinforced materials. Higher gas-to-metal ratios of 4.45, as opposed to lower gas-to-metal ratios of 1.95 produced a refined grain structure with an evenly distributed second phase. In both unreinforced and MMC materials, alloys with zinc contents over 12 wt. % attained the highest concentration of structural particles. One alloy displayed high strengths exceeding all others in the study. The superior strength properties were attributed to the addition of scandium, which produced a fine dispersion of the Al3Sc phase. This finely dispersed phase created additional strengthening through, coherency mismatch of Al3Sc and Al3(Sc,Zr) precipitates with the matrix, and ordered particle strengthening. The spray formed extrusions exhibited a loss in fracture resistance (K Q), compared to IM 7075 alloys. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differential between the matrix and precipitate zone. The MMC materials displayed a large increase in fatigue strength compared to commercial IM 7075-T6 and -T7 alloys. The enhanced fatigue performance of the spray formed alloys is attributed to low crack growth rates, which are a consequence of inhomogeneous slip. It is believed that the massive presence of coherent and semicoherent (GP zones and eta' phase) particles of reduced dimension in the spray formed alloys allowed a highly inhomogeneous slip behavior, where a slip reverse mechanism was operative.

  3. Metal Nanowires: Synthesis, Processing, and Structure-Property Relationships in the Context of Flexible Transparent Conducting Films

    Science.gov (United States)

    Rathmell, Aaron R.

    The demand for flat-panel televisions, e-readers, smart-phones, and touch-screens has been increasing over the past few years and will continue to increase for the foreseeable future. Each of these devices contains a transparent conductor, which is usually indium tin oxide (ITO) because of its high transparency and low sheet resistance. ITO films, however, are brittle, expensive, and difficult to deposit, and because of these problems, alternative transparent electrodes are being studied. One cheap and flexible alternative to ITO is films of randomly oriented copper nanowires. We have developed a synthesis to make long, thin, and well-dispersed copper nanowires that can be suspended in an ink and coated onto a substrate to make flexible transparent films. These films are then made conductive by annealing in a hydrogen atmosphere or by a solution processing technique that can be done in air at room temperature. The resulting flexible transparent conducting films display transparencies and sheet resistance values comparable to ITO. Since it is well known that copper oxidizes, we also developed a synthesis to coat the copper nanowires with a layer of nickel in solution. Our measurements indicated that copper nanowires would double their sheet resistance in 3 months, but the sheet resistance of cupronickel nanowire films containing 20 mole% nickel will double in about 400 years. The addition of nickel to the copper nanowires also gave the film a more neutral grey appearance. The nickel coating can also be applied to the copper nanowires after the film is formed via an electroless plating method. To further optimize the properties of our transparent conductors we developed a framework to understand how the dimensions and area coverage of the nanowires affect the overall film properties. To quantify the effect of length on the sheet resistance and transmittance, wires with different lengths but the same diameter were synthesized to make transparent conducting films and finite-difference time-domain calculations were used to determine the effect of the nanowire diameter on the film's transmittance. The experimental data and calculations were then incorporated into random resistor network simulations that demonstrated that wires with an aspect ratio of 400 or higher are required to make a network that transmits >90% of visible light while maintaining a sheet resistance below 100 O/sq-1. These properties, and the fact that copper and nickel are 1000 times more abundant than indium or silver, make copper and cupronickel nanowire films a promising alternative for the sustainable, efficient production of transparent conductors.

  4. Properties–structure relationship research on LiCaPO4:Eu2+ as blue phosphor for NUV LED application

    International Nuclear Information System (INIS)

    Graphical abstract: The graphical abstract shows the excitation and emission spectrum of LiCaPO4:Eu2+, and the CIE coordinates of LiCaPO4:Eu2+. The inset shows the photo of blue LED prepared by LiCaPO4:Eu2+ and NUV chip. It indicates that this phosphor can be excited by UV light and emit strong greenish-blue light. Highlights: •Pure phase blue phosphors of LiCaPO4:Eu2+ with a hexagonal structure were first prepared via solid-state method. •The crystallographic site of Eu2+ ion in the LiCaPO4 lattice was identified as 8-fold Ca2+ site. •The phosphor exhibits excellent thermal stability and the corresponding mechanism was thermal assisted ionization. •Bright and high color purity blue LED prototype based on LiCaPO4:Eu2+ phosphor was fabricated. -- Abstract: Blue-emitting phosphors of Eu2+-activated LiCaPO4 with a hexagonal structure were prepared via a conventional solid-state method. The XRD, PL spectra and thermal quenching were applied to characterize the phosphors. The crystallographic site of Eu2+ ion in the LiCaPO4 lattice was identified and discussed. The optimized LiCaPO4:0.03Eu2+ exhibits the bright greenish-blue emission with CIE coordinates of (0.119, 0.155) and a quantum efficiency of 52%. The critical energy-transfer distance was confirmed as ?18 Å by both calculated crystal structure method and experimental spectral method. The thermal stability of LiCaPO4:Eu2+ was evaluated by temperature-dependent PL spectra, and the thermal quenching mechanism was found to be thermal assisted ionization. Prototype blue LEDs with high color purity and good current stability were fabricated

  5. Relationships between ferrisol properties and the structure of plant parasitic nematode communities on sugarcane in Martinique (French West Indies)

    OpenAIRE

    Cadet, Patrice; Thioulouse, J.; Albrecht, Alain (coord.)

    1994-01-01

    Les relations entre les variations de la structure d'un ferrisol et celles des peuplements de nématodes phytoparasites de la canne à sucre ont été étudiées le long de trois transects. Ces transects, d'une vingtaine de m de long commencent dans un horizon A et se terminent dans une zone remodelée où affleure l'horizon C. Les résultats ont été analysés à l'aide d'une analyse de co-inertie qui permet d'étudier simultanément un tableau pédologique et un tableau nématologique. La variation progres...

  6. Relationship between structural and magnetic properties in (Ti,Fe)O2 powders obtained by mechanical milling

    International Nuclear Information System (INIS)

    Fe-doped TiO2 samples with different Fe content were prepared by mechanical alloying starting from TiO2 rutile and FeO. The samples were structurally and magnetically characterized by XRD, Mössbauer spectroscopy, X-ray absorption spectroscopy (XAS), AC-susceptibility and magnetization measurements. XAS results showed that Fe ions were incorporated into the rutile phase with oxygen coordination that was lower than that expected in this phase. The oxygen coordination number decreased with the increase of Fe2+ ions such as it was previously found in the milled samples of TiO2 doped with hematite. The RT Mössbauer spectra were reproduced using two paramagnetic interactions, one corresponding to Fe2+ (??0.87 mm/s) and the other to Fe3+ (??0.31 mm/s). Magnetometry measurements showed the presence of paramagnetic and ferromagnetic-like interactions at room temperature. Although saturation and coercivity of the ferromagnetic phase increased with iron, the effective magnetic moment per iron atom decreased, probably due to the precipitation of Fe rich antiferromagnetic structures.

  7. Quantitative Structure Property Relationship Modeling for Prediction of Retention Index for a Set of Some Organic Compounds

    Directory of Open Access Journals (Sweden)

    Mehdi Rahimi

    2012-06-01

    Full Text Available

    One of the most ubiquitous challenges of the scientists is the theoretical evaluation of experimental parameters to validate and improve their ability. Plant essential oils and their extracts have been greatly employed in folk medicine, food flavoring, fragrance and pharmaceutical industries. This work is a part of our comprehensive investigation to correlate the experimental and calculated retention indices (RI of the some organic compounds from K. Javidnia et al. The structures of all organic compounds were drawn into the HYPERCHEM program and optimized using semi-empirical AM1 method, applying a gradient limit of 0.01 kcal/Å as a stopping criterion for optimized structures prior to geometry optimization step. Then molecular descriptors were calculated for each compound by the DRAGON software on the minimal energy conformations. The Stepwise SPSS was used for the selection of the variables that resulted in the best fitted models. By molecular modeling and calculation of descriptors, four significant descriptors (XMOD, PCD, MATS2e, GATS2e related to the retention indices values of the essential oils, were identified. After the variables selection, the MLR method used for building the regression models. The statistical figures obtained by the proposed model are R2=0.989, RMSEP=53.08, REP =3.83 and SEP =54.94. In the final step, models generated were used to predict the retention index for a set of test compounds.

  8. Structure-property relationships of symmetrical and asymmetrical azobenzene derivatives as gelators and their self-assemblies.

    Science.gov (United States)

    Balamurugan, Rathinam; Kai-Ming, Wu; Chien, Chih-Chieh; Liu, Jui Hsiang

    2014-11-28

    Two different series of symmetrical and asymmetrical azobenzenes containing terminal cholesteryl/adamantyl derivatives (SAC/SAA and AAC) with varying spacer lengths (alkyl chains) have been developed. The gelation and aggregation of these derivatives were studied relative to structural motifs, spacer lengths, solvent affinity, temperatures and light conditions. Among these derivatives, the cholesteryl derivatives that have short alkyl chains (nanoparticles at CGCs. These nanoparticles were further entangled to form interconnected fibrous structures when the concentration was increased above the CGC (according to the SEM and TEM analyses). Secondary forces (van der Waals/H-bonding) and ?-? stacking played important roles in the aggregation of both series in the solvents according to variable temperature (1)H-NMR analysis. The reversibility of sol-gel transitions by light was studied with respect to solvent affinity. This study revealed that reversible transitions were only observed in the non-polar solvents, as supported by the FTIR analysis of the gelators in the various solvents. The thermal and mesomorphic behaviors of the gelators by DSC (Differential Scanning Calorimetry) and POM (Polarized Optical Microscopy) analyses revealed that the chiral nematic (N*) and cholesteric mesophase (Ch*) were exhibited by only the short and longer alkyl chain cholesteryl derivatives, respectively. However, the cholesteryl derivative without a spacer (AAC0) did not exhibit any liquid crystalline phase but acted as an efficient gelator relative to the other gelators in this study. PMID:25290740

  9. Structure-Property Relationship of Layered Metal Oxide Phosphonate/Chitosan Nanohybrids for Transducer in Biosensing Device

    Science.gov (United States)

    De, Sriparna; Mohanty, Smita; Nayak, Sanjay Kumar

    2015-01-01

    A candid approach to analyze the performance characteristics of phenyl phosphonate-functionalized zirconium oxide and pure zirconium oxide (ZrO2) fillers reinforced chitosan nanocomposites and their suitability as a potential biomaterial for the development of transducer surface in biosensing device has been investigated in this communication. Functionalization of ZrO2 has been carried out using sulfophenylphosphonate which was confirmed using Fourier transform infrared spectrographs. The electrostatic intercalation of chitosan with filler particles was monitored using electrochemical impedance analyzer which exhibits lowest bulk resistance which is highly effective for ionic switching. Incorporation of zirconium sulfophenylphosphonate (ZrSP) the ionic conductivity of the chitosan film attained a value of 1.2 × 10-6 S/cm as compared to the unmodified one which is a prefeasibility work for the fabrication of biosensing platform. Variation in performance characteristics has been evaluated through morphological and thermal characterization. TGA and DSC analysis reveal that the thermal stability and decomposition temperature of the nanocomposites were improved by the addition of reinforcing filler particles. XRD and SEM and TEM results support the above assumption. The continuous alignment of the proton transfer channels of the nanocomposites was thoroughly investigated by AFM analysis which revealed phase morphology for improved enzyme entrapment. Further, surface functionalized nanofillers result considerable increment of mechanical properties in terms of elastic modulus and tensile stress.

  10. Plant extracts with anti-inflammatory properties--a new approach for characterization of their bioactive compounds and establishment of structure-antioxidant activity relationships.

    Science.gov (United States)

    Amaral, Sónia; Mira, Lurdes; Nogueira, J M F; da Silva, Alda Pereira; Helena Florêncio, M

    2009-03-01

    Geranium robertianum L. (Geraniacea) and Uncaria tomentosa (Willd.) DC. (Rubiaceae) plant extracts, frequently used in traditional medicine for treatment of inflammatory and cancer diseases, were studied to identify potential bioactive compounds that may justify their therapeutic use and their underlying mechanisms of action. Since some of the pharmacological properties of these plant extracts may be linked to their antioxidant potential, the antioxidant activity, in relation to free radical scavenging, was measured by the ABTS/HRP and DPPH() assays, presenting U. tomentosa the higher activity. The antioxidant activity was also evaluated by scavenging of HOCl, the major strong oxidant produced by neutrophils and a potent pro-inflammatory agent. U. tomentosa was found to be a better protector against HOCl, which may justify its effectiveness against inflammatory diseases. SPE/LC-DAD was used for separation/purification purposes and ESI-MS/MS for identification/characterization of the major non-volatile components, mainly flavonoids and phenolic acids. The ESI-MS/MS methodology proposed can be used as a model procedure for identification/characterization of unknowns without the prerequisite for standard compounds analysis. The ESI-MS/MS data obtained were consistent with the antioxidant activity results and structure-activity relationships for the compounds identified were discussed. PMID:19201196

  11. 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

    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 activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the 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 activity are compared side by side and strong evidence found that electronic effects, in

  12. Similarity Matrices Quantitative Structure-Activity Relationships for Anticonvulsant Phenylacetanilides

    Directory of Open Access Journals (Sweden)

    Ovidiu Ivanciuc

    2004-07-01

    Full Text Available Molecular graph descriptors are used in developing structure-property models, in drug design, virtual synthesis, similarity and diversity assessment. We present a new application of topological indices in computing similarity matrices that are subsequently used to develop quantitative structure-property relationship and quantitative structure-activity relationship models. The molecular structure is described by similarity matrices obtained from similarity indices calculations, when each molecule is compared to every other from the data set. Four similarity indices are introduced for the computation of the molecular similarity from a set of topological indices that numerically characterize the structure of chemical compounds. Using the multilinear regression model, the significant columns from the similarity matrices are selected as independent variables in a structure-activity study of anticonvulsant phenylacetanilides. The results obtained show that similarity matrices derived from molecular graph descriptors can provide the basis for the investigation of quantitative structure-activity relationships.

  13. Structure/Property Relationships in Erodible Multilayered Films: Influence of Polycation Structure on Erosion Profiles and the Release of Anionic Polyelectrolytes

    OpenAIRE

    Zhang, Jingtao; Fredin, Nathaniel J.; Janz, John F.; Sun, Bin; Lynn, David M.

    2006-01-01

    We have investigated the influence of polymer structure on the erosion profiles of multilayered polyelectrolyte assemblies fabricated from sodium poly(styrene sulfonate) (SPS) and three different hydrolytically degradable polyamines. We synthesized three structurally related poly(?-amino ester)s (polymers 1?3) having systematic variations in both charge density and hydrophobicity. These changes in structure did not influence film thickness significantly, but polymer structure was found to ...

  14. Structure-Property Relationships in Porous 3-D Nanostructures as a Function of Preparation Conditions: Isocyanate Cross-Linked Silica Aerogels

    Science.gov (United States)

    Meador, Mary Ann B.; Capadona, Lynn A.; McCorkle, Linda; Papadopoulos, Demetrios S.; Leventis, Nicholas

    2007-01-01

    Sol-gel derived silica aerogels are attractive candidates for many unique thermal, optical, catalytic, and chemical applications because of their low density and high mesoporosity. However, their inherent fragility has restricted use of aerogel monoliths to applications where they are not subject to any load. We have previously reported cross-linking the mesoporous silica structure of aerogels with di-isocyanates, styrenes or epoxies reacting with amine decorated silica surfaces. These approaches have been shown to significantly increase the strength of aerogels with only a small effect on density or porosity. Though density is a prime predictor of properties such as strength and thermal conductivity for aerogels, it is becoming clear from previous studies that varying the silica backbone and size of the polymer cross-link independently can give rise to combinations of properties which cannot be predicted from density alone. Herein, we examine the effects of four processing parameters for producing this type of polymer cross-linked aerogel on properties of the resulting monoliths. We focus on the results of 13C CP-MAS NMR which gives insight to the size and structure of polymer cross-link present in the monoliths, and relates the size of the cross-links to microstructure, mechanical properties and other characteristics of the materials obtained.

  15. Comparative Study of Structure-Property Relationships in Polymer Networks Based on Bis-GMA, TEGDMA and Various Urethane-Dimethacrylates

    Directory of Open Access Journals (Sweden)

    Izabela Barszczewska-Rybarek

    2015-03-01

    Full Text Available The effect of various dimethacrylates on the structure and properties of homo- and copolymer networks was studied. The 2,2-bis-[4-(2-hydroxy-3- methacryloyloxypropoxyphenyl]-propane (Bis-GMA, triethylene glycol dimethacrylate (TEGDMA and 1,6-bis-(methacryloyloxy-2-ethoxycarbonylamino-2,4,4-trimethylhexane (HEMA/TMDI, all popular in dentistry, as well as five urethane-dimethacrylate (UDMA alternatives of HEMA/TMDI were used as monomers. UDMAs were obtained from mono-, di- and tri(ethylene glycol monomethacrylates and various commercial diisocyanates. The chemical structure, degree of conversion (DC and scanning electron microscopy (SEM fracture morphology were related to the mechanical properties of the polymers: flexural strength and modulus, hardness, as well as impact strength. Impact resistance was widely discussed, being lower than expected in the case of poly(UDMAs. It was caused by the heterogeneous morphology of these polymers and only moderate strength of hydrogen bonds between urethane groups, which was not high enough to withstand high impact energy. Bis-GMA, despite having the highest polymer morphological heterogeneity, ensured fair impact resistance, due to having the strongest hydrogen bonds between hydroxyl groups. The TEGDMA homopolymer, despite being heterogeneous, produced the smoothest morphology, which resulted in the lowest brittleness. The UDMA monomer, having diethylene glycol monomethacrylate wings and the isophorone core, could be the most suitable HEMA/TMDI alternative. Its copolymer with Bis-GMA and TEGDMA had improved DC as well as all the mechanical properties.

  16. From building blocks of proteins to drugs: A quantum chemical study on structure-property relationships of phenylalanine, tyrosine and dopa

    CERN Document Server

    Ganesan, Aravindhan; Wang, Feng

    2014-01-01

    Density functional theory and ab initio methods have been employed to address the impacts of hydroxyl (OH) group substitutions on the physico-chemical properties of levodopa (or L-dopa) against the natural amino acids, phenylalanine and tyrosine. L-dopa, which is an important therapeutic drug for Parkinson's disease, shares structural homology with the amino acids, whose structures differ only by OH substitutions in their phenyl side chains. It is revealed that the backbone geometries of the aromatic molecules do not show apparent OH-dependent differences; however, their other molecular-level properties, such as molecular dipole moment, electronic properties and aromaticity, change significantly. The core binding energy spectra indicate that the atom sites that undergo modifications exhibit large energy shifts, so as to accommodate the changes in the intra-molecular chemical environment of the molecules. The binding energies of the modified C 1s sites in the molecules shift as much as 1.8 eV, whereas the elec...

  17. Dislocations in single hemp fibres-investigations into the relationship of structural distortions and tensile properties at the cell wall level

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; Eder, M.

    2007-01-01

    The relationship between dislocations and mechanical properties of single hemp fibres (Cannabis sativa L. var. Felina) was studied using a microtensile testing setup in a 2-fold approach. In a first investigation the percentage of dislocations was quantified using polarized light microscopy (PLM) prior to microtensile testing of the fibres. In a second approach PLM was used to monitor the dislocations while straining single fibres. The first part of the study comprised 53 hemp fibres with up to 20% of their cell wall consisting of dislocations. For this data set the percentage of dislocations did not affect the mechanical properties. In the second part of the study it was found that dislocations disappeared during tensile testing, and that they did not reappear until several weeks after failure. A strain stiffening effect due to the straightening of the dislocations was not observed. It is possible that the former positions of the dislocations functioned as locations for crack initiation. However, the crack does not propagate transversely all the way trough the dislocation but results in a shear failure between the microfibrils. In rheological studies fibres were strained at constant stress levels, and dislocations that had disappeared did not reappear during that period.

  18. Quantitative structure-property relationships for predicting subcooled liquid vapor pressure ( PL) of 209 polychlorinated diphenyl ethers (PCDEs) by DFT and the position of Cl substitution (PCS) methods

    Science.gov (United States)

    Zeng, Xiaolan; Wang, Zunyao; Ge, Zhigang; Liu, Hongxia

    Optimization of the molecular geometry of 209 polychlorinated diphenyl ethers (PCDEs) and diphenyl ether (DE) were carried out at the B3LYP/6-31G* level with Gaussian 98 program. Based on the theoretical linear solvation energy relationship (TLSER) model, the obtained structural parameters were taken as theoretical descriptors to establish the first novel QSPR model (I) for predicting subcooled liquid vapor pressure ( PL) of PCDEs. The model (I) achieved in this work contains three variables: most negative atomic partial charge in molecule ( q-), dipole moment of the molecules ( ?) and mean molecular polarizability ( ?), of which r2=0.988, SD=0.134. Meanwhile, it was found that there was significant correlation between the Cl substitution positions and some structural parameters. Consequently, the numbers of Cl substitution positions were also taken as theoretical descriptors to establish the second novel QSPR model (II) for predicting PL of all PCDE congeners, of which r2=0.991, SD=0.112. In addition, the t-values of two models are both large and the variation inflation factors (VIF) of variables herein are all less than 5.0, suggesting significant statistics of the PL predicting models. And the results of cross-validation test also showed that the second model exhibited optimum stability and better predictive power. Moreover, results of prediction were further compared with data from similar studies by semi-empirical PM3 method, molecular connectivity indices (MCIs) method and molecular descriptors method.

  19. Metallomesogens. Structure and properties

    International Nuclear Information System (INIS)

    The original investigations of ferrocene mesogens with general formula Fe(C5H4C(CH3)=N-N=CHC6H4COOC6H4OCnH2n+1)2 and their solutions in liquid crystalline solvents by Moessbauer spectroscopy as well as by calorimetry, thermomicroscopic and X-ray analysis are discussed. The data on electron, molecular and crystal structures, polymorphism and dynamical properties of these substances and frozen solutions are presented. For ferrocene mesogens and their solutions, aligned by external magnetic field, the values of order parameter and inter- and intramolecular contributions to the nuclear vibrational anisotropy of central metal atom are estimated. (author) 16 refs.; 4 figs.; 2 tabs

  20. Structure-property relationship of bifunctional MnO2 nanostructures: highly efficient, ultra-stable electrochemical water oxidation and oxygen reduction reaction catalysts identified in alkaline media.

    Science.gov (United States)

    Meng, Yongtao; Song, Wenqiao; Huang, Hui; Ren, Zheng; Chen, Sheng-Yu; Suib, Steven L

    2014-08-13

    Manganese oxides of various structures (?-, ?-, and ?-MnO2 and amorphous) were synthesized by facile methods. The electrocatalytic properties of these materials were systematically investigated for catalyzing both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in alkaline media. Extensive characterization was correlated with the activity study by investigating the crystal structures (XRD, HRTEM), morphologies (SEM), porosities (BET), surfaces (XPS, O2-TPD/MS), and electrochemical properties (Tafel analysis, Koutechy-Levich plots, and constant-current electrolysis). These combined results show that the electrocatalytic activities are strongly dependent on the crystallographic structures, and follow an order of ?-MnO2 > AMO > ?-MnO2 > ?-MnO2. Both OER studies and ORR studies reveal similar structure-determined activity trends in alkaline media. In the OER studies, ?-MnO2 displays an overpotential of 490 mV compared to 380 mV shown by an Ir/C catalyst in reaching 10 mA cm(-2). Meanwhile, ?-MnO2 also exhibits stability for 3 h when supplying a constant current density of 5 mA cm(-2). This was further improved by adding Ni(2+) dopants (ca. 8 h). The superior OER activity was attributed to several factors, including abundant di-?-oxo bridges existing in ?-MnO2 as the protonation sites, analogous to the OEC in PS-II of the natural water oxidation system; the mixed valencies (AOS = 3.7); and the lowest charge transfer resistances (91.8 ?, ? = 430 mV) as revealed from in situ electrochemical impedance spectroscopy (EIS). In the ORR studies, when reaching 3 mA cm(-2), ?-MnO2 shows 760 mV close to 860 mV for the best ORR catalyst (20% Pt/C). The outstanding ORR activity was due to the strongest O2 adsorption capability of ?-MnO2 suggested by temperature-programmed desorption. As a result, this discovery of the structure-related electrocatalytic activities could provide guidance in the further development of easily prepared, scalable, and low-cost catalysts based on metal oxides and their derivatives. PMID:25058174

  1. Porous Materials - Structure and Properties

    DEFF Research Database (Denmark)

    Nielsen, Anders

    1997-01-01

    The paper presents some viewpoints on the description of the pore structure and the modelling of the properties of the porous building materials. Two examples are given , where it has been possible to connect the pore structure to the properties: Shrinkage of autoclaved aerated concrete and the properties of lime mortar.

  2. Understanding the relationships between structural features and optical/magnetic properties when designing Fe(1-x)Mg(x)MoO4 as piezochromic compounds.

    Science.gov (United States)

    Blanco-Gutierrez, Veronica; Demourgues, Alain; Toulemonde, Olivier; Wattiaux, Alain; Nguyen, Olivier; Gaudon, Manuel

    2015-03-01

    Fe1-xMgxMoO4 compounds with x = 0, 0.25, 0.5, 0.75, and 1.0 were obtained after annealing under inert gas at T = 700 °C. All of the compounds exhibit a pressure-induced and/or temperature-induced phase transition between the two polymorphs adopted by AMoO4 compounds (A = Mn, Fe, Co, and Ni). For the FeMoO4 compound, for both the ? and the ? allotropic forms, the structural features have been correlated to the magnetic properties, the Mössbauer signals, and the optical absorption properties to gain a better understanding of the phenomena at the origin of the piezo(thermo)chromic behavior. The different contributions of the Mössbauer signals were attributed to the different Fe(2+) ions or Fe(3+) ions from the structural data (Wyckoff positions, bond distances and angles) and were quantified. Furthermore, the low Fe(3+) concentration (9 and 4 mol?%, respectively, in the ? and the ? allotropic forms) was also quantified based on the magnetic susceptibility measurements. The net increase in the Fe(3+) quantity in the ?-form in comparison to the ?-form, which is associated with the occurrence of Fe-Mo charge transfer, is at the origin of the important divergence of coloration of the two forms. To design new piezo(thermo)chromic oxides and to control the pressure (temperature) of this first-order phase transition, FeMoO4-MgMoO4 solid solutions were synthesized. The optical contrast between the two allotropic forms was increased due to magnesium incorporation, and the phase transition (? ? ?) pressure increased steadily with the Mg content. A new generation of nontoxic and chemically stable piezochromic compounds that are sensible to various pressures was proposed. PMID:25664488

  3. Investigation of structure-dielectric property relationships in zirconium oxide, tantalum pentoxide, and oxide-polymer laminate films for high energy density capacitor applications

    Science.gov (United States)

    Sethi, Guneet

    Pulsed power applications involve transformation of electrical energy into high-peak power pulses through capacitors. There is an immediate need for fast-response capacitors with decreased volume, weight, and cost for pulsed power applications and power distribution systems. This research challenge is dominated by energy density. Energy density is directly related to dielectric properties such as dielectric polarization, conductivity and breakdown strength of the capacitor dielectric. This research work correlates processing and microstructure of single and multiple component dielectric films with their dielectric properties. The inorganic materials studied in this dissertation include zirconium oxide (ZrO2) and tantalum pentoxide (Ta 2O5) reactive sputtered films. Film crystallization & structure was studied as a function of sputtering growth variables such as sputtering power, sputtering pressure, source frequency, oxygen pressure, substrate temperature, substrate material, and post-deposition annealing temperature. Polycrystalline phase of ZrO2 and amorphous phase of Ta2O 5 were obtained for most sputtering growth variables. Although the amorphous films have lower permittivity (32 for amorphous & 51 for polycrystalline at 1 kHz), they also have lower AC and DC conductivities (3.4x10-8 S/m for amorphous & 12.2x10 -8 S/m for polycrystalline at 1 kHz), which result in high breakdown strength than polycrystalline films. Amorphous Ta2O5 films are found to be ideal for high-energy density capacitors with energy density of 14 J/cm3 because of their high permittivity, low leakage current density, and high dielectric breakdown strength. Oxide films were combined with different polymers (polyvinyldene flouride-triflouroethylene, polypropylene and polyethylene terephthalate) to produce two different kinds of laminate composites---oxide on polymer and polymer on oxide. Permittivity and conductivity differences in the polymer and oxide films result in an impedance contrast of generally greater than 100 between the constituents. Low and high field dielectric properties were characterized for both laminate composites. All the dielectric films were characterized by impedance spectroscopy at frequencies ranging from 10 mHz to 1 MHz at different temperatures. Complex impedance and modulus analyses were used to resolve the contributions of individual microstructural features (such as grain, grain boundary & interface) from the overall film and composite electrical properties. Activation energies related to electro-active regions (grain boundary ˜1.1 eV, grain ˜0.5 eV) in the film structure were also determined from the temperature dependent impedances. The overall polarization of composite was higher by at least 25% than the sum of the polarizations from the individual layers for all composites. Plasma processed Ta2O5-Polypropylene laminate composite resulted in breakdown strength of ˜870 MV/m, which approximately 10% higher breakdown strength than its highest breakdown constituent (˜775 MV/m). These improved properties were attributed to bulk polymer modification, interface charge blocking/trapping and impedance contrast within the composite. The effect of impedance contrast on breakdown strength was modeled through permittivity contrast using Monte Carlo method. The breakdown model explored the electrostatic effects of adding a high permittivity barrier within an existing dielectric on the breakdown tree. The model also provided knowledge on various breakdown tree characteristics such as speed and shape. The Monte Carlo simulation results suggest that the experimentally observed impedance contrast of 1000 between the layers of the laminate composite can result in improved breakdown strength.

  4. The relationship between amyloid structure and cytotoxicity

    Science.gov (United States)

    Marshall, Karen E; Marchante, Ricardo; Xue, Wei-Feng; Serpell, Louise C

    2014-01-01

    Self-assembly of proteins and peptides into amyloid structures has been the subject of intense and focused research due to their association with neurodegenerative, age-related human diseases and transmissible prion diseases in humans and mammals. Of the disease associated amyloid assemblies, a diverse array of species, ranging from small oligomeric assembly intermediates to fibrillar structures, have been shown to have toxic potential. Equally, a range of species formed by the same disease associated amyloid sequences have been found to be relatively benign under comparable monomer equivalent concentrations and conditions. In recent years, an increasing number of functional amyloid systems have also been found. These developments show that not all amyloid structures are generically toxic to cells. Given these observations, it is important to understand why amyloid structures may encode such varied toxic potential despite sharing a common core molecular architecture. Here, we discuss possible links between different aspects of amyloidogenic structures and assembly mechanisms with their varied functional effects. We propose testable hypotheses for the relationship between amyloid structure and its toxic potential in the context of recent reports on amyloid sequence, structure, and toxicity relationships. PMID:24819071

  5. 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 from the literature, from experimental measurements and from molecular simulations for complex molecules. The interest of such models in the selection of molecules can be shown for example by the trade-off between cold flow properties and density of paraffinic compounds. If the carbon chain length is too high, the cold flow properties are compromised. One solution can be to increase branching or incorporate fuel base with good cold flow properties such as naphthenic or aromatic compounds. However, this leads to a decrease in density below the jet fuel specification. Again, using naphthenic of alkyl-aromatic compounds produced from biomass can help. Le développement des carburants alternatifs est en plein essor, notamment dans le domaine aéronautique. Cela se concrétise par la possibilité d’incorporer jusqu’à 50 % de carburants de synthèse de type Fischer- Tropsch (FT ou hydroprocessed esters and fatty acids (HEFA dans du carburéacteur. De même, ces carburants paraffiniques se développent pour le transport terrestre en parallèle des biocarburants à base d’esters ou d’alcool actuellement disponibles. La formulation de ces carburants alternatifs est actuellement basée sur une sélection des produits via des critères physiques. L’atteinte de ces critères se fait souvent par des formulations empiriques et ce type de fonctionnement ne s’avère pas très efficace et montre ses limites. En effet, les carburants alternatifs présentent des propriétés chimiques qui peuvent être différentes en fonction du procédé (répartition n-paraffines/iso-paraffines, longueur de chaîne, ramification, etc. et donc modulable. Ainsi, une nouvelle voie pourrait être envisagée visant à déterminer par le calcul, la molécule (ou le mélange de molécules la plus à même de répondre au cahier des charges du carburant, puis à étudier ou à optimiser les voies de synthèse permettant d’accéder à ces produits. Le travail présenté a pour objectif le développement et l’application de méthodes QSPR (Quantitative Structure Property Relationship perm

  6. Structure-properties relationships in triarylamine-based donor-acceptor molecules containing naphtyl groups as donor material for organic solar cells

    Science.gov (United States)

    Mohamed, Salma; Demeter, Dora; Laffitte, Jean-Alex; Blanchard, Philippe; Roncali, Jean

    2015-03-01

    The effects of replacing the phenyl rings of triphenylamine (TPA) by naphtyl groups are analysed on a series of push-pull molecules containing a 2-thienyl-dicyanovinyl acceptor group. UV-Vis absorption spectroscopy and cyclic voltammetry show that the introduction of one or two naphtyl groups in the structure has limited effects on the optical properties and energy levels of the molecule. On the other hand, the evaluation of the compounds as donor material in bi-layer solar cells with C60 as acceptor shows that the number and mode of linkage of the naphtyl groups exert a marked influence on the power conversion efficiency (PCE) of the cell. Two naphtyl groups lead to a decrease of PCE with respect to TPA, while a single naphtyl group produces opposite effects depending on the linking mode. Compared to TPA, an alpha-naphtyl group leads to a small decrease of PCE while in contrast a beta-naphtyl leads to a ~35% increase of PCE due to improved short-circuit current density (Jsc) and fill-factor. The determination of the hole-mobility of these two donors by the space-charge-limited current method shows that these effects are correlated with the higher hole-mobility of the ?-naphtyl compound.

  7. Structure-properties relationships in triarylamine-based donor-acceptor molecules containing naphtyl groups as donor material for organic solar cells.

    Science.gov (United States)

    Mohamed, Salma; Demeter, Dora; Laffitte, Jean-Alex; Blanchard, Philippe; Roncali, Jean

    2015-01-01

    The effects of replacing the phenyl rings of triphenylamine (TPA) by naphtyl groups are analysed on a series of push-pull molecules containing a 2-thienyl-dicyanovinyl acceptor group. UV-Vis absorption spectroscopy and cyclic voltammetry show that the introduction of one or two naphtyl groups in the structure has limited effects on the optical properties and energy levels of the molecule. On the other hand, the evaluation of the compounds as donor material in bi-layer solar cells with C60 as acceptor shows that the number and mode of linkage of the naphtyl groups exert a marked influence on the power conversion efficiency (PCE) of the cell. Two naphtyl groups lead to a decrease of PCE with respect to TPA, while a single naphtyl group produces opposite effects depending on the linking mode. Compared to TPA, an alpha-naphtyl group leads to a small decrease of PCE while in contrast a beta-naphtyl leads to a ~35% increase of PCE due to improved short-circuit current density (Jsc) and fill-factor. The determination of the hole-mobility of these two donors by the space-charge-limited current method shows that these effects are correlated with the higher hole-mobility of the ?-naphtyl compound. PMID:25761773

  8. Structure-properties relationships in triarylamine-based donor-acceptor molecules containing naphtyl groups as donor material for organic solar cells

    Science.gov (United States)

    Mohamed, Salma; Demeter, Dora; Laffitte, Jean-Alex; Blanchard, Philippe; Roncali, Jean

    2015-01-01

    The effects of replacing the phenyl rings of triphenylamine (TPA) by naphtyl groups are analysed on a series of push-pull molecules containing a 2-thienyl-dicyanovinyl acceptor group. UV-Vis absorption spectroscopy and cyclic voltammetry show that the introduction of one or two naphtyl groups in the structure has limited effects on the optical properties and energy levels of the molecule. On the other hand, the evaluation of the compounds as donor material in bi-layer solar cells with C60 as acceptor shows that the number and mode of linkage of the naphtyl groups exert a marked influence on the power conversion efficiency (PCE) of the cell. Two naphtyl groups lead to a decrease of PCE with respect to TPA, while a single naphtyl group produces opposite effects depending on the linking mode. Compared to TPA, an alpha-naphtyl group leads to a small decrease of PCE while in contrast a beta-naphtyl leads to a ~35% increase of PCE due to improved short-circuit current density (Jsc) and fill-factor. The determination of the hole-mobility of these two donors by the space-charge-limited current method shows that these effects are correlated with the higher hole-mobility of the ?-naphtyl compound. PMID:25761773

  9. RELATIONSHIP BETWEEN BOARD STRUCTURE AND CONSERVATISM

    Directory of Open Access Journals (Sweden)

    Shahram Gilaninia

    2011-10-01

    Full Text Available The rule of conservatism plays an important role for the. Corporate governance, data collection mechanism provides. Thereby to ensure that company assets are used efficiently. And improper distribution of assets to be managers and other groups prevent. In this paper, the relationship between board structure and conservatism has been studied. The sample includes 55 companies listed in Tehran Stock Exchange during the period 1385 to 1389.The period of investigation, gathering information about the study variables were the companies listed in Tehran Stock Exchange. The data in this study, both descriptive and inferential statistics using excel software and spss16 has been analyzed. The inferential statistics of Pearson correlation test and regression analysis, Thedescriptive statistics and data analysis using the mean and standard deviation are. The results indicate that test hypotheses, No relationship between board structure characteristics with the level of conservatism in the company are not listed in Tehran Stock Exchange.

  10. Structure-activity relationships of the nikkomycins.

    Science.gov (United States)

    Decker, H; Zähner, H; Heitsch, H; König, W A; Fiedler, H P

    1991-08-01

    The structure-activity relationships of different nikkomycins were studied to evaluate the structural requirements for a potent chitin synthase inhibitor. We investigated the transport of the nikkomycins via the peptide transport system of the yeast Yarrowia lipolytica and determined the kinetic parameters for nikkomycin Z uptake [Km = 24 microM, Vmax = 2.2 nmol min-1 (mg dry wt)-1]. We demonstrated that the beta-methyl group of the N-terminal amino acid of dipeptide nikkomycins protects the molecule against peptidase activity in crude cell-extracts of different fungi. Furthermore, the relationship between inhibition constants for chitin synthase, transport of the nikkomycins via the peptide transport system, susceptibility to degradation by cellular proteases and whole-cell activity of the nikkomycins are discussed. PMID:1955867

  11. The Structures & Properties of Carbon

    Science.gov (United States)

    Castellini, Olivia M.; Lisensky, George C.; Ehrlich, Jennifer; Zenner, Greta M.; Crone, Wendy C.

    2006-01-01

    The four main forms of carbon--diamond, graphite, buckyballs, and carbon nanotubes (CNTs)--are an excellent vehicle for teaching fundamental principles of chemical bonding, material structure, and properties. Carbon atoms form a variety of structures that are intrinsically connected to the properties they exhibit. Educators can take advantage of…

  12. RELATIONSHIP BETWEEN BOARD STRUCTURE AND CONSERVATISM

    OpenAIRE

    Shahram Gilaninia; Reza Salimi Chena; Behnam Shadi Dizaj; Seyyed Javad Mousavian

    2011-01-01

    The rule of conservatism plays an important role for the. Corporate governance, data collection mechanism provides. Thereby to ensure that company assets are used efficiently. And improper distribution of assets to be managers and other groups prevent. In this paper, the relationship between board structure and conservatism has been studied. The sample includes 55 companies listed in Tehran Stock Exchange during the period 1385 to 1389.The period of investigation, gathering information about...

  13. Structural relationships in high temperature superconductors

    International Nuclear Information System (INIS)

    The recent discovery of two types of metallic copper oxide compounds which are superconducting to above 900K has renewed interest in the search for new high temperature superconducting materials. It is significant that both classes of compounds, La/sub 2-x/Sr/sub x/CuO/sub 4-y/ and YBa2Cu3O/sub 7-?/ are intimately related to the extensively studied perovskite family. Both compounds contain highly oxidized, covalently bonded Cu-O sublattices, however, they differ in geometry. In this paper we discuss the relationship of these features to the superconducting properties. 30 refs., 6 figs

  14. Structure-antioxidant activity relationships of flavonoids and phenolic acids.

    Science.gov (United States)

    Rice-Evans, C A; Miller, N J; Paganga, G

    1996-01-01

    The recent explosion of interest in the bioactivity of the flavonoids of higher plants is due, at least in part, to the potential health benefits of these polyphenolic components of major dietary constituents. This review article discusses the biological properties of the flavonoids and focuses on the relationship between their antioxidant activity, as hydrogen donating free radical scavengers, and their chemical structures. This culminates in a proposed hierarchy of antioxidant activity in the aqueous phase. The cumulative findings concerning structure-antioxidant activity relationships in the lipophilic phase derive from studies on fatty acids, liposomes, and low-density lipoproteins; the factors underlying the influence of the different classes of polyphenols in enhancing their resistance to oxidation are discussed and support the contention that the partition coefficients of the flavonoids as well as their rates of reaction with the relevant radicals define the antioxidant activities in the lipophilic phase. PMID:8743980

  15. Properties of fast solitary structures

    Directory of Open Access Journals (Sweden)

    R. E. Ergun

    1999-01-01

    Full Text Available We present detailed observations of electromagnetic waves and particle distributions from the Fast Auroral SnapshoT (FAST satellite which reveal many important properties of large-amplitude, spatially-coherent plasma structures known as "fast solitary structures" or "electron phase space holes". Similar structures have been observed in several regions of the magnetosphere including the auroral zone, plasma sheet boundary layer, and bow shock. There has been rapid theoretical progress in understanding these structures. Solitary structures can develop from bidirectional electron beams. Once developed, the one-dimensional properties parallel to the magnetic field can be adequately described by analytical treatment as BGK structures. There remains, however, several unanswered questions. The origin of the bidirectional electron beams, the development of two-or three-dimensional structures, and the observed association with the ion cyclotron frequency are not well understood.

  16. Structural relationships and vasorelaxant activity of monoterpenes

    Directory of Open Access Journals (Sweden)

    Cardoso Lima Tamires

    2012-09-01

    Full Text Available Abstract Background and purpose of the study The hypotensive activity of the essential oil of Mentha x villosa and its main constituent, the monoterpene rotundifolone, have been reported. Therefore, our objective was to evaluate the vasorelaxant effect of monoterpenes found in medicinal plants and establish the structure-activity relationship of rotundifolone and its structural analogues on the rat superior mesenteric artery. Methods Contractions of the vessels were induced with 10??M of phenylephine (Phe in rings with endothelium. During the tonic phase of the contraction, the monoterpenes (10-8 - 10-3, cumulatively were added to the organ bath. The extent of relaxation was expressed as the percentage of Phe-induced contraction. Results The results from the present study showed that both oxygenated terpenes (rotundifolone, (+-limonene epoxide, pulegone epoxide, carvone epoxide, and (+-pulegone and non-oxygenated terpene ((+-limonene exhibit relaxation activity. The absence of an oxygenated molecular structure was not a critical requirement for the molecule to be bioactive. Also it was found that the position of ketone and epoxide groups in the monoterpene structures influence the vasorelaxant potency and efficacy. Major conclusion The results suggest that the presence of functional groups in the chemical structure of rotundifolone is not essential for its vasorelaxant activity.

  17. Ginkgolides and glycine receptors : a structure-activity relationship study

    DEFF Research Database (Denmark)

    Jaracz, Stanislav; Nakanishi, Koji

    2004-01-01

    Ginkgolides from the Ginkgo biloba tree are diterpenes with a cage structure consisting of six five-membered rings and a unique tBu group. They exert a variety of biological properties. In addition to being antagonists of the platelet activating factor receptor (PAFR), it has recently been shown that native ginkgolides are potent and selective antagonists of the inhibitory glycine receptor. Forty new ginkgolide derivatives have been prepared in good to high yields on milligram scales and investigated for their antagonistic properties at homomeric alpha 1 glycine receptors, thus providing the first structure-activity relationship study of ginkgolides at glycine receptors. A high-throughput screening assay showed that native ginkgolide C was the most potent ligand, and that manipulation of any of the hydroxyl groups led to loss of activity at alpha 1 glycine receptors.

  18. The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kevin Magniez

    2013-08-01

    Full Text Available The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%.

  19. Structural Relationships and Vasorelaxant Activity of Monoterpenes

    Directory of Open Access Journals (Sweden)

    Tamires Cardoso Lima

    2012-09-01

    Full Text Available Background and purpose of the study The hypotensive activity of the essential oil of Mentha x villosa and its main constituent, the monoterpene rotundifolone, have been reported. Therefore, our objective was to evaluate the vasorelaxant effect of monoterpenes found in medicinal plants and establish the structureactivity relationship of rotundifolone and its structural analogues on the rat superior mesenteric artery. Methods:Contractions of the vessels were induced with 10 muM of phenylephine (Phe in rings with endothelium. During the tonic phase of the contraction, the monoterpenes (10-8 - 10-3, cumulatively were added to the organ bath. The extent of relaxation was expressed as the percentage of Phe-induced contraction. Results:The results from the present study showed that both oxygenated terpenes (rotundifolone, (+- limonene epoxide, pulegone epoxide, carvone epoxide, and (+-pulegone and nonoxygenated terpene ((+-limonene exhibit relaxation activity. The absence of an oxygenated molecular structure was not a critical requirement for the molecule to be bioactive. Also it was found that the position of ketone and epoxide groups in the monoterpene structures influence the vasorelaxant potency and efficacy. Major conclusion The results suggest that the presence of functional groups in the chemical structure of rotundifolone is not essential for its vasorelaxant activity.

  20. Structure-cytotoxicity relationships for dietary flavonoids

    DEFF Research Database (Denmark)

    Breinholt, V.; Dragsted, L.O.

    1998-01-01

    The cytotoxicity of a large series of dietary flavonoids was tested in a non-tumorigenic mouse and two human cancer cell lines, using the neutral red dye exclusion assay. All compounds tested exhibited a concentration-dependent cytotoxic action in the employed cell lines. The relative cytotoxicity of the flavonoids, however, Tvas found to vary greatly among the different cell Lines. With a few exceptions, the investigated flavonoids were more cytotoxic to the human cancer cell lines, than the mouse cell line. The differences in cytotoxicity were accounted for in part by differences in cellular uptake and metabolic capacity among the different cell types. In 3T3 cells fairly consistent structure-cytotoxicity relationships were found. The most cytotoxic structures tested in 3T3 cells were flavonoids with adjacent 3',4' hydroxy groups on the B-ring, such as luteolin, quercetin, myricetin, fisetin, eriodictyol, and taxifolin. The structural requirements for cytotoxicity in the human cell lines, however, were lessclear. Reduction of the cytotoxic response of the 3',4'-hydroxylated flavonoid, quercetin, by the hydroxyl radical scavenger mannitol and the metal chelator desferozamine suggests that reactive oxygen species, produced from redox cycling of the catechol structure with molecular oxygen, is responsible in part for the cytotoxicity of this subgroup of flavonoids.

  1. Structure-phase morphology - Property relationship of a series of light-emitting alternating copolymers with distyrylbenzenes segments and oligo(ethylene oxide) spacers

    International Nuclear Information System (INIS)

    A series of light-emitting alternating copolymers: DSB-TEO, DSB-SEO, DSB-PEO1500 and dimethoxy(DM)DSB-SEO, consisting of 1,4-distyrylbenzene (DSB) and different length of ionic conducting oligomer ethylene oxide (OEO) spacers, were synthesized. The thermal stabilities, electrochemical behavior and photoluminescent properties of these polymers were studied systematically. It was found that with increasing OEO chain length, the solubility, film-forming property and relative fluorescence quantum yield were improved accordingly. The introduction of two methoxy groups as side chains into the DSB segment to form DMDSB not only enhanced the film-forming property, but also improved the quantum efficiency of the polymer. Phase contrast microscopy, polarized optical microscopy and atomic force microscopy (AFM) were employed to investigate the phase morphology of the thin films prepared from the pure polymer or polymer/LiCF3SO3 blends. Results revealed that compared with pure polymer thin films, there was significant change in the phase morphology of the thin films prepared from polymer/LiCF3SO3 blends. The reason could be attributed to the contrary roles of dissolved and undissolved lithium salt played in the polymer matrix, which was discussed in detail in the paper. Phase morphology study of DMDSB-SEO revealed that, compared with DSB-SEO, there was much less crystallization of OEO segments and the solubility of lithium sa segments and the solubility of lithium salt had increased greatly. Furthermore, AFM was used to investigate the dependence of surface morphology on the spin-coat processing conditions, such as the solvents, substrates and rotation rate. A light-emitting electrochemical cell device of the copolymer was fabricated, and the brightness and maximum external quantum efficiency of the device were investigated

  2. Structure-activity relationship and properties optimization of a series of Quinazoline-2,4-diones as inhibitors of the canonical Wnt pathway.

    Science.gov (United States)

    Nencini, Arianna; Pratelli, Carmela; Quinn, Joanna M; Salerno, Massimiliano; Tunici, Patrizia; De Robertis, Alessandra; Valensin, Silvia; Mennillo, Federica; Rossi, Marco; Bakker, Annette; Benicchi, Tiziana; Cappelli, Federico; Turlizzi, Elisa; Nibbio, Martina; Caradonna, Nicola P; Zanelli, Ugo; Andreini, Matteo; Magnani, Matteo; Varrone, Maurizio

    2015-05-01

    Wnt signaling pathway plays a critical role in numerous cellular processes, including tumor initiation, proliferation, invasion/infiltration, metastasis formation and resistance to chemotherapy. In a drug discovery project aimed at the identification of inhibitors of the canonical Wnt pathway, we selected a series of quinazoline 2,4-diones as starting point for the therapeutic treatment of glioblastoma multiforme. Despite of poor physico-chemical properties of hit compound 1, our medicinal chemistry effort allowed the discovery and characterization of lead compound 33 (SEN461), with improved ADME profile, good bioavailability and active in vitro and in vivo in glioblastoma, gastric and sarcoma tumors. PMID:25847770

  3. Structural properties of copper

    Science.gov (United States)

    Jona, F.; Marcus, P. M.

    2001-03-01

    First-principles total-energy calculations on the tetragonal states of bulk elemental copper have been made with a full-potential electronic structure program with both the local-density approximation (LDA) and the generalized gradient approximation (GGA). The unique path through tetragonal states produced by epitaxial strain on equilibrium states has been found. This path, called the epitaxial Bain path, shows that body-centered cubic Cu (at axial ratio c/a=1) is unstable, but a shallow energy minimum exists for a body-centered tetragonal (bct) state with axial ratio c/a=0.93. Structure parameters and elastic constants of both the face-centered cubic (fcc) ground state and the bct state are determined and the fcc values are compared to experiment: the GGA results are better than the LDA results. The procedures for evaluating the three fcc elastic constants and the six tetragonal elastic constants are described in detail. Tests of the stability of the bct phase at c/a=0.93 show that this phase, although stable with respect to tetragonal deformations, is unstable with respect to [110] shear in the (001) plane. A lower-energy body-centered orthorhombic phase is found that may be metastable.

  4. Aggregation-structure-elasticity relationship of gels

    Science.gov (United States)

    Ma, Hang-Shing

    Aerogel is a mesoporous, low-density material which is desirable for applications like thermal insulation and low-k interlayer dielectric. However, its lack of mechanical integrity hinders its development. Experiments have shown that aerogels exhibit a scaling relationship E ? rho m between modulus E and density rho, with the exponent m usually between 3 and 4. The objective of the dissertation is to use computer modeling to understand how the random aggregation process accounts for the fractal structure and the compliant nature of aerogels. Model gels were created by the diffusion-limited cluster-cluster aggregation (DLCA), which simulates random aggregation leading to the sol-gel transition. Then each resulting structure was modeled as an elastic beam network and numerically compressed using the finite element method (FEM). Analyses showed that the DLCA gels reproduced the scaling relationship after trimming the non-contributive dangling branches from the mechanically efficient looped networks. The dangling bond deflection (DEF) model was therefore developed to model the random rotational movement of the dangling branches and the subsequent loop structure formation. Model gels with extensive loops and negligible dangling branches were simulated by combining the DLCA and DEF models. Representation of the aerogel networks by the DLCADEF models was validated for the resemblance of the fractal geometry and elastic behavior. The lack of mechanical integrity in aerogels is a natural consequence of the random aggregation and the resulting fractal structure. Fractal clusters are created in the early stage of aggregation, each of which is characterized by a dense core and sparse perimeter. These clusters grow in size until they percolate at the gel point by knitting together at the perimeters. The gel structure possesses a "blob-and-link" architecture, with the blobs representing the rigid cores of the fractal clusters, and the links corresponding to the tenuous chains formed between the clusters at percolation. Finite element analysis illustrates that the strain energy always localizes at the links in the DLCADEF gels. Therefore the stiffness of an aerogel is reduced by the presence of these compliant links. The key to synthesizing stiffer gels is to homogenize the distribution and cross-linking of mass during the formation of the network.

  5. Relationship between structure and properties in high-temperature Bi(Al0.5Fe0.5)O3-PbTiO3 piezoelectric ceramics

    International Nuclear Information System (INIS)

    Highlights: ? Low-cost Bi-based high temperature piezoceramics. ? A new high temperature system with Curie point >478 deg. C, compared to BiScO3-PbTiO3 (450 deg. C). ? Effectively improve the poling conditions. - Abstract: Ceramic samples of xBi(Al0.5Fe0.5)O3-(1 - x)PbTiO3 (BAF-PT, x = 0.05-0.5) solid solutions were fabricated using the conventional solid state reaction method. X-ray diffraction analysis revealed that all compositions can form single perovskite phase with tetragonal symmetry. The relationship between the tetragonal lattice parameters, tetragonality c/a, cell volume, and ferro-piezoelectric characterization as a function of x was systematically investigated. The BAF modification can effectively improve the poling condition at a proper BAF content. A combination of piezoelectric constant of d33 (50-60 pC/N), electromechanical planar coupling coefficients of kp (20.3-22.5%), and high Curie temperature Tc (>478 deg. C) suggested that BAF-PT could be a good candidate for high-temperature piezoelectric applications.

  6. Structure-Property Relations in Nonferrous Metals

    Science.gov (United States)

    Russell, Alan; Loong Lee, Kok

    2005-05-01

    A long-awaited text that fills the void in non-ferrous metallurgy literature While most undergraduate metallurgy textbooks focus on iron, the most commercially important metallic element, Structure-Property Relations in Nonferrous Metals is a comprehensive textbook covering the remaining eighty-two nonferrous metals. Designed to be readily accessible to materials engineering students at all academic levels, the text describes the relationships between the atomic-, crystal-, and micro-structures of nonferrous metals, and such physical behaviors as strength, ductility, electrical conductivity, and corrosion. In order to capture and retain students' interest, the authors maintain a strong focus on practical application. Each chapter supplements fundamental concepts with engaging examples from actual engineering case studies and industrial projects, directly relating content to real-world application. Part One describes the general concepts of crystal- and micro-structures and the implications of these structures for the mechanical, thermal, and electronic properties of nonferrous metals, intermetallic compounds, and metal matrix composites. Chapters focus on such relevant topics as: Point, line, and planar defects and their effects on a material's properties Dislocations and strengthening mechanisms Fracture and fatigue Strain rate effects and creep Deviations from classic crystallinity Processing methods Composites and intermetallic compounds Part Two builds on Part One by exploring how the concepts presented define the properties of a particular metallic element and its alloys, and how these properties contribute to the engineering uses of each nonferrous metal. An accompanying ftp site contains homework problems, appendices, bibliographies, and tables of data indicating the nations producing metallic elements and the quantities produced. Structure-Property Relations in Nonferrous Metals is a valuable reference for both students in undergraduate metallurgy courses and practicing engineers.

  7. Structure–mechanical property relationship in a high strength low carbon alloy steel processed by two-step intercritical annealing and intercritical tempering

    International Nuclear Information System (INIS)

    The influence of annealing and tempering temperature on the microstructure and mechanical properties was investigated in a low carbon alloy steel that was processed by a two-step intercritical annealing and intercritical tempering heat treatment. In general, the microstructure of the processed steel comprises intercritical lath-like ferrite, bainitic/martensitic lath and acicular-type retained austenite. The lower intercritical annealing temperature resulted in lower fraction of intercritical ferrite with finer grain size and consequently higher strength. On the other hand, the intercritical tempering temperature significantly influenced retained austenite content and precipitation. High fraction of retained austenite was obtained at a temperature slightly above Ac1 temperature and retained austenite content decreased with increase in tempering temperature. This behavior is attributed to the competition between the enrichment of Mn and Ni and the fraction of reversed austenite. Fine niobium carbide precipitates of size ?2–6 nm and copper precipitates of size range ?10–30 nm were obtained. The optimal intercritical annealing and tempering temperatures to obtain the product of tensile strength and elongation % of ?30 GPa% were 780 °C and 660 °C, respectively and the volume fraction of retained austenite was ?29%

  8. Structure–mechanical property relationship in a high strength low carbon alloy steel processed by two-step intercritical annealing and intercritical tempering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, W.H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Wang, X.L. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Venkatsurya, P.K.C. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Guo, H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Shang, C.J., E-mail: cjshang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States)

    2014-06-01

    The influence of annealing and tempering temperature on the microstructure and mechanical properties was investigated in a low carbon alloy steel that was processed by a two-step intercritical annealing and intercritical tempering heat treatment. In general, the microstructure of the processed steel comprises intercritical lath-like ferrite, bainitic/martensitic lath and acicular-type retained austenite. The lower intercritical annealing temperature resulted in lower fraction of intercritical ferrite with finer grain size and consequently higher strength. On the other hand, the intercritical tempering temperature significantly influenced retained austenite content and precipitation. High fraction of retained austenite was obtained at a temperature slightly above Ac{sub 1} temperature and retained austenite content decreased with increase in tempering temperature. This behavior is attributed to the competition between the enrichment of Mn and Ni and the fraction of reversed austenite. Fine niobium carbide precipitates of size ?2–6 nm and copper precipitates of size range ?10–30 nm were obtained. The optimal intercritical annealing and tempering temperatures to obtain the product of tensile strength and elongation % of ?30 GPa% were 780 °C and 660 °C, respectively and the volume fraction of retained austenite was ?29%.

  9. Structure-interfacial properties relationship and quantification of the amphiphilicity of well-defined ionic and non-ionic surfactants using the PIT-slope method.

    Science.gov (United States)

    Ontiveros, Jesús F; Pierlot, Christel; Catté, Marianne; Molinier, Valérie; Salager, Jean-Louis; Aubry, Jean-Marie

    2015-06-15

    The Phase Inversion Temperature of a reference C10E4/n-Octane/Water system exhibits a quasi-linear variation versus the mole fraction of a second surfactant S2 added in the mixture. This variation was recently proposed as a classification tool to quantify the Hydrophilic-Lipophilic Balance (HLB) of commercial surfactants. The feasibility of the so-called PIT-slope method for a wide range of well-defined non-ionic and ionic surfactants is investigated. The comparison of various surfactants having the same dodecyl chain tail allows to rank the polar head hydrophilicity as: SO3Na?SO4Na?NMe3Br>E2SO3Na?CO2Na?E1SO3Na?PhSO3Na>IsosorbideexoSO4Na?IsosorbideendoSO4Na?E8?NMe2O>E7>E6?Glucosyl>E5?Diglyceryl?E4>E3>E2?Isosorbideexo>Glyceryl>Isosorbideendo. The influence on the surfactant HLB of other structural parameters, i.e. hydrophobic chain length, unsaturation, replacement of Na(+) by K(+) counterion, and isomerism is also investigated. Finally, the method is successfully used to predict the optimal formulation of a new bio-based surfactant, 1-O-dodecyldiglycerol, when performing an oil scan at 25°C. PMID:25744856

  10. SnO{sub 2} nanocrystals synthesized by microwave-assisted hydrothermal method: towards a relationship between structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Paulo G. [UEPG-Universidade Estadual de Ponta Grossa, Department of Materials Science, INCTMN, LIMAC, CIPP (Brazil); Moreira, Mario L., E-mail: mlucio@liec.ufscar.br [UNESP-Universidade Estadual Paulista, Department of Physical Chemistry, Institute of Chemistry, INCTMN, LIEC (Brazil); Tebcherani, Sergio M. [UEPG-Universidade Estadual de Ponta Grossa, Department of Materials Science, INCTMN, LIMAC, CIPP (Brazil); Orlandi, Marcelo O. [UNESP-Universidade Estadual Paulista, Department of Physical Chemistry, Institute of Chemistry, INCTMN, LIEC (Brazil); Andres, J. [University of Jaume I, Department of Experimental Sciences (Spain); Li, Maximu S. [USP, Instituto de Fisica, INCTMN (Brazil); Diaz-Mora, Nora [Parque Tecnologico de Itaipu (PTI), Laboratorio de Materiais (LAMAT/UNIOESTE) (Brazil); Varela, Jose A.; Longo, Elson [UNESP-Universidade Estadual Paulista, Department of Physical Chemistry, Institute of Chemistry, INCTMN, LIEC (Brazil)

    2012-03-15

    The exploration of novel synthetic methodologies that control both size and shape of functional nanostructure opens new avenues for the functional application of nanomaterials. Here, we report a new and versatile approach to synthesize SnO{sub 2} nanocrystals (rutile-type structure) using microwave-assisted hydrothermal method. Broad peaks in the X-ray diffraction spectra indicate the nanosized nature of the samples which were indexed as a pure cassiterite tetragonal phase. Chemically and physically adsorbed water was estimated by TGA data and FT-Raman spectra to account for a new broad peak around 560 cm{sup -1} which is related to defective surface modes. In addition, the spherical-like morphology and low dispersed distribution size around 3-5 nm were investigated by HR-TEM and FE-SEM microscopies. Room temperature PL emission presents two broad bands at 438 and 764 nm, indicating the existence of different recombination centers. When the size of the nanospheres decreases, the relative intensity of 513 nm emission increases and the 393 nm one decreases. UV-Visible spectra show substantial changes in the optical absorbance of crystalline SnO{sub 2} nanoparticles while the existence of a small tail points out the presence of localized levels inside the forbidden band gap and supplies the necessary condition for the PL emission.

  11. Structural properties of Haeckelite nanotubes

    International Nuclear Information System (INIS)

    The name 'Haeckelite' has been proposed to designate a three-fold coordinated network generated by a periodic arrangement of pentagons, hexagons and heptagons (Terrones H et al 2000 Phys.-Rev.-Lett 84-1716). Starting-from a planar Haeckelite array, tubular structures are obtained by applying the same wrapping procedure as for the usual nanotubes, which are rolled up sheets of graphene. This paper is a short review of the structural properties of Haeckelite nanotubes, as investigated by computer molecular modelling. The Haeckelite nanotubes may adopt various shapes, among which coiled structures, double-screw molecules, corrugated cylinders, and pearl-necklace-like nanotubes are the most spectacular. It is shown that some of these structures may explain exotic forms of C nanostructures revealed by electron microscopy on samples produced experimentally. The identification of the possible Haeckelite structure of a nanotube by electron diffraction and scanning tunnelling microscopy is discussed

  12. Distributing Correlation Coefficients of Linear Structure-Activity/Property Models

    Directory of Open Access Journals (Sweden)

    Sorana D. BOLBOACA

    2011-12-01

    Full Text Available Quantitative structure-activity/property relationships are mathematical relationships linking chemical structure and activity/property in a quantitative manner. These in silico approaches are frequently used to reduce animal testing and risk-assessment, as well as to increase time- and cost-effectiveness in characterization and identification of active compounds. The aim of our study was to investigate the pattern of correlation coefficients distribution associated to simple linear relationships linking the compounds structure with their activities. A set of the most common ordnance compounds found at naval facilities with a limited data set with a range of toxicities on aquatic ecosystem and a set of seven properties was studied. Statistically significant models were selected and investigated. The probability density function of the correlation coefficients was investigated using a series of possible continuous distribution laws. Almost 48% of the correlation coefficients proved fit Beta distribution, 40% fit Generalized Pareto distribution, and 12% fit Pert distribution.

  13. Composition - structure - property relationships in bioactive glasses

    OpenAIRE

    Watts, Sally

    2010-01-01

    Hench developed the first bioactive material, Bioglass®, based on a soda-lime phospho-silicate glass. Most materials, elicit a neutral response when implanted into the human body. Bioglass®, however, was seen to create a positive response by depositing the body’s natural bone substance, Hydroxyapatite on its surface. Although it is recognised that compositional modifications effect bioactivity, there is very little comprehension of the composition-structureproperty relation...

  14. Structural-optical relationships in first-year sea ice

    Science.gov (United States)

    Light, Bonnie

    2000-12-01

    The optical properties of sea ice are governed by the distribution of brine and gas inclusions, and precipitated salt crystals within the ice. Laboratory experiments designed to understand structural-optical relationships and their dependence on temperature in first-year sea ice were carried out. Detailed observations of the microstructure of isothermal samples of natural sea ice were obtained for temperatures between -33 and -2°C. Changes in apparent optical properties of cylindrical samples cut from the same ice core were monitored simultaneously. A cylindrical Monte Carlo radiative transfer model was developed to infer inherent optical properties from the radiance data. Experimental results were used to develop and test a structural-optical model necessary for detailed radiative transfer modeling in sea ice. Microstructure observations were initially carried out at -15°C to obtain inclusion size distributions. Brine pocket dimensions were found to range from 0.01 mm to 10 mm, with number densities averaging about 30 mm-3. Observed vapor bubbles had radii less than 0.2 mm and number densities approximately 1 mm-3. Both these estimates are an order of magnitude larger than number densities previously reported. Results indicate that structural-optical relationships in sea ice can be described by three regimes. At temperatures below -23°C, optical properties change dramatically, and are most affected by the precipitation of hydrohalite. At temperatures between -23 and -8°C, they remain fairly constant where effects from changes in the mass of precipitated mirabilite crystals are offset by changes in the size of brine inclusions. At temperatures between -8 and -2°C, only small changes in the optical properties of the ice were observed, despite large observed increases in the cross-sectional area of the inclusions. This was discovered to be related to a significant increase in bulk asymmetry parameter resulting from a decrease in the refractive index of brine. We expect this general pattern will be found in most types of sea ice, regardless of the exact distribution of inclusions. These results suggest that it is possible to develop simple parameterizations of radiative transfer in sea ice appropriate for incorporation into large-scale climate models and GCMs.

  15. Structural changes in latosols of the cerrado region: I - relationships between soil physical properties and least limiting water range / Alterações estruturais de latossolos representativos da região do cerrado: I - relações entre propriedades físicas do solo e intervalo hídrico ótimo

    Scientific Electronic Library Online (English)

    Eduardo da Costa, Severiano; Geraldo César de, Oliveira; Moacir de Souza, Dias Júnior; Katia Aparecida de Pinho, Costa; Fabiano Guimarães, Silva; Silvio Marcos, Ferreira Filho.

    2011-06-01

    Full Text Available Apesar do elevado potencial agrícola dos Latossolos da região do Cerrado brasileiro, quando inseridos no processo produtivo sob sistemas de manejo inadequados, o seu espaço poroso pode ser seriamente alterado, levando à sua rápida degradação. Como consequência, tem-se observado aceleração do process [...] o erosivo e assoreamento dos mananciais associados na paisagem. Dessa forma, o presente trabalho teve por objetivo avaliar as alterações estruturais de Latossolos do município de Rio Verde, GO, por meio da caracterização do intervalo hídrico ótimo (IHO), e as relações entre IHO e demais propriedades físicas desses solos. O estudo foi conduzido utilizando-se amostras coletadas no horizonte Bw de cinco Latossolos oxídicos representativos da variabilidade textural observada nos Latossolos ocorrentes no bioma Cerrado. Foram determinados o IHO e os atributos físico-hídricos dos solos em diversos estados de compactação induzidos por compressão uniaxial. Os resultados indicaram que a compactação do solo resultou desde benefícios ao crescimento das plantas, relacionados ao aumento na retenção de água, até condições de severas restrições às suas funções edáficas, sendo observadas relações inversas entre o conteúdo de argila e os valores de densidade do solo (Ds) nas diversas condições estruturais. A Ds correspondente à macroporosidade crítica do solo (DscMAC) foi mais restritiva ao manejo sustentável dos Latossolos estudados que a Ds crítica correspondente ao IHO (DscIHO). A maior compactação permissível observada nesses Latossolos oxídicos deve-se à elevada porosidade de aeração conferida pela estrutura do tipo granular. Abstract in english The agricultural potential of Latosols of the Brazilian Cerrado region is high, but when intensively cultivated under inappropriate management systems, the porosity can be seriously reduced, leading to rapid soil degradation. Consequently, accelerated erosion and sedimentation of springs and creeks [...] have been observed. Therefore, the objective of this study was to evaluate structural changes of Latosols in Rio Verde, Goiás, based on the Least Limiting Water Range (LLWR), and relationships between LLWR and other physical properties. Soil samples were collected from the B horizons of five oxidic Latosols representing the textural variability of the Latosols of the Cerrado biome. LLWR and other soil physical properties were determined at various soil compaction degrees induced by uniaxial compression. Soil compaction caused effects varying from enhanced plant growth due to higher water retention, to severe restriction of edaphic functions. Also, inverse relationships were observed between clay content and bulk density values (Bd) under different structural conditions. Bd values corresponding to critical soil macroporosity (BdcMAC) were more restrictive to a sustainable use of the studied Latosols than the critical Bd corresponding to LLWR (BdcLLWR). The high tolerable compression potential of these oxidic Latosols was related to the high aeration porosity associated to the granular structure.

  16. Structure-activity relationships in Werner clathrates

    International Nuclear Information System (INIS)

    The synthesis and characterization of a series of inorganic coordination compounds which, upon crystallization, have the ability to include solvent or guest molecules spatially within the lattice are reported. The compounds have the following general formula: [NiX2B4] - where X is isothiocyanate or bromine and B is 4-ethylpyridine, 4-vinylpiridine or 3,5-dimethylpyridine; [NiX2B2]n - where X is isothiocyanate, B is 2-aminopyridine and n indicates it is a polymer; [NiX2AB2]2 - where X is isothiocyanate, B is 3-aminopyridine (two of these four ligands in the dimer are bridging) and A is water. The various guest molecules have been carefully chosen, according to their point symmetry, which is a key factor in yielding structures of a particular type. The structures of seventeen compounds have been elucidated by single crystal x-ray analysis. The difficulty has been found to lie in refining disordered guest molecules. Other techniques employed in the initial characterization of these compounds are Microanalysis, Mass Spectrometry and UV/Visible Spectrophotometry. An intramolecular potential energy study on the [Ni(NCS)2(3,5-diMepy)4] complex reveals that the orthohydrogens on the 3,5-dimethylpyridine ligands control the conformation of the molecule. Packing densities and volume comparisons of the [Ni(NCS)2(4-Etpy)4] and [Ni(NCS)2(4-)4] and [Ni(NCS)2(4-Vipy)4] complexes and their clathrates have been carried out. The exact sizes and shapes of the cavities in which the guest molecules are located in the x-ray crystal structures have been evaluated by both intermolecular potential energy and molecular volume calculations. Thermodynamic and spectroscopic properties of the [Ni(NCS)2(4-Etpy)4] and [Ni(NCS)2(4-Vipy)4] clathrates have been studied in both solution and the solid state. The techniques used are x-ray powder diffractometry, IR spectroscopy and Thermogravimetry (including Differential Thermal Analysis). 70 figs., 35 tabs., 125 refs

  17. The Relationship between Residential Property Development and Property Tax generation in Ibadan North, Oyo State

    OpenAIRE

    Ajayi M. T. A.; Rukaiyat, Ogunbajo A.; Abass, Sule I.; Abdulkareem Sekinat

    2014-01-01

    This paper examined the relationship between residential property development and property tax generation in Ibadan North Local Government, Oyo State- Nigeria. Data on residential properties within the Local Government for an eleven year period (1999 – 2010) was obtained from the appropriate planning authority, while records of property taxes generated within the same eleven year period was sourced from the taxing authority within the local government. Regression analysis was used to examin...

  18. Structure activity relationships of novel antiepileptic drugs.

    Science.gov (United States)

    Mittapalli, G K; Roberts, E

    2014-01-01

    Despite notable success over years in the discovery and development of new antiepileptic drugs (AEDs), about 30-40% of the patients are resistant to drug treatment. There is a still significant need to develop novel AEDs that demonstrate superior efficacy, broad spectrum of activities and good safety profile. The synaptic vesicle glycoprotein 2A (SV2A), ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) and voltage-gated potassium channels (KCNQ2/Q3) are clinically validated as new molecular targets for epilepsy. The discovery of SV2A as a target for levetiracetam, 2,3-benzodiazepine GYKI 52466 as a non-competitive AMPA-R antagonist and retigabine as a KCNQ2/Q3 channels activator provided a rational basis to develop novel AEDs. The optimization of SV2A binding affinity of levetiracetam led to the discovery of novel high affinity SV2A ligands that displayed superior efficacy and protective index in animal models of epilepsy. The high-throughput screening (HTS) and medicinal chemistry efforts yielded many non-competitive AMPA-R antagonists of which perampanel was recently approved as a first-in-a new class. The efficacy and lack of sub-type selectivity of retigabine prompted many research efforts to discover several potent and selective KCNQ2/Q3 channel activators of distinct chemical scaffolds that are at various stages of clinical development. Despite the known role of galanin and galanin receptor (Gal-R) in epilepsy over a decade, development of potent and brainpenetrant Gal-R agonists is very challenging. The discovery of selective Gal-R2 positive allosteric modulator, CYM 2503, offers a valuable and an alternative approach. The review focuses on the available structure-activity relationships and preclinical efficacy of novel antiepileptic compounds that are distinct from most of the approved AEDs, specifically SV2A ligands, non-competitive AMPA-R antagonists, KCNQ2/Q3 channels activators and Gal-R modulators. PMID:24251563

  19. Optical properties of multilayer structures

    Science.gov (United States)

    Lebedev, M. S.; Ayupov, B. M.; Smirnova, T. P.

    2009-01-01

    The possibility of using the ellipsometry method for investigation of the optical properties of multilayer films and structures is shown. The optical properties of structures HfO2/SiO2/Si, HfO2/Si, ZrO2/Si, Ta2O5/Si, and Al2O3/Si are studied. It is found that a layer of hafnium silicate is formed at the interface between the HfO2 film and Si. Annealing of the structures in oxygen shows that oxides studied are oxygen-permeable and that the thickness of SiO2 at the film-substrate interface increases. The growth rate of SiO2 layers depends on the chemical nature of an oxide. Al2O3 films are impermeable for oxygen diffusion. The production of layers of alloys (Al2O3) x (HfO2)1 - x is optimized, which allows one to obtain layers with a homogeneous distribution of elements over the thickness.

  20. Relationship between protein structure and geometrical constraints

    DEFF Research Database (Denmark)

    Lund, Ole; Hansen, Jan

    1996-01-01

    We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the effect of using predicted secondary structure and surface assignments. The constraints used in this approach typically may be obtained from low-resolution experimental data. When using a cost function based on distances, half of the resulting structures will be mirrored, because the resulting structure and its mirror image will have the same cost. The secondary structure assignments were therefore divided into chirality constraints and distance constraints. Here we report that the problem of mirrored structures, in some cases, can be solved by using a chirality term in the cost function.

  1. Relationship between protein structure and geometrical constrains

    DEFF Research Database (Denmark)

    Lund, Ole; Hansen, Jan

    1996-01-01

    We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the effect of using predicted secondary structure and surface assignments. The constraints used in this approach typically may be obtained from low-resolution experimental data. When using a cost function based on distances, half of the resulting structures will be mirrored, because the resulting structure and its mirror image will have the same cost. The secondary structure assignments were therefore divided into chirality constraints and distance constraints. Here we report that the problem of mirrored structures, in some cases, can be solved by using a chirality term in the cost function.

  2. Quasicrystals Structure and Physical Properties

    CERN Document Server

    Trebin, Hans-Rainer

    2003-01-01

    A comprehensive and up-to-date review, covering the broad range of this outstanding class of materials among intermetallic alloys. Starting with metallurgy and characterization, the authors continue on to structure and mathematical modeling. They use this basis to move on to dealing with electronic, magnetic, thermal, dynamic and mechanical properties, before finally providing an insight into surfaces and thin films. The authors belong to a research program on quasicrystals, sponsored by the German Research Society and managed by Hans-Rainer Trebin, such that most of the latest results are pre

  3. Relationship between Static Stiffness and Modal Stiffness of Structures

    Directory of Open Access Journals (Sweden)

    Tianjian Ji Tianjian Ji

    2010-02-01

    Full Text Available This paper derives the relationship between the static stiffness and modal stiffness of a structure. The static stiffness and modal stiffness are two important concepts in both structural statics and dynamics. Although both stiffnesses indicate the capacity of the structure to resist deformation, they are obtained using different methods. The former is calculated by solving the equations of equilibrium and the latter can be obtained by solving an eigenvalue problem. A mathematical relationship between the two stiffnesses was derived based on the definitions of two stiffnesses. This relationship was applicable to a linear system and the derivation of relationships does not reveal any other limitations. Verification of the relationship was given by using several examples. The relationship between the two stiffnesses demonstrated that the modal stiffness of the fundamental mode was always larger than the static stiffness of a structure if the critical point and the maximum mode value are at the same node, i.e. for simply supported beam and seven storeys building are 1.5% and 15% respectively. The relationship could be applied into real structures, where the greater the number of modes being considered, the smaller the difference between the modal stiffness and the static stiffness of a structure.

  4. COMPRESSION DEFORMATION AND STRUCTURAL RELATIONSHIPS OF COOKED RICE

    Science.gov (United States)

    Cooked rice quality is based on factors including texture which is related to structure. The texture-structure relationship can be explored by correlating compression measurements to structural observation of the compressed material. Compression ratios of 20, 30, 40, 50, 60 and 70% were measured aga...

  5. Effect of processing on Polymer/Composite structure and properties

    Science.gov (United States)

    1982-01-01

    Advances in the vitality and economic health of the field of polymer forecasting are discussed. A consistent and rational point of view which considers processing as a participant in the underlying triad of relationships which comprise materials science and engineering is outlined. This triad includes processing as it influences material structure, and ultimately properties. Methods in processing structure properties, polymer science and engineering, polymer chemistry and synthesis, structure and modification and optimization through processing, and methods of melt flow modeling in processing structure property relations of polymer were developed. Mechanical properties of composites are considered, and biomedical materials research to include polymer processing effects are studied. An analysis of the design technology of advances graphite/epoxy composites is also reported.

  6. [Taxoids: structural and experimental properties].

    Science.gov (United States)

    Lavelle, F; Combeau, C; Commerçon, A

    1995-04-01

    Paclitaxel (Taxol) and docetaxel (Taxotere) are the first representatives of a new class of antitumor compounds. These two taxoids are clinically active against breast, ovarian and lung cancers. Taxoids are highly complex diterpenoids form natural origin. Preclinical and clinical developments have been made possible after a long and sustained chemical effort: paclitaxel is extracted from the barks of the Pacific yew tree Taxus brevifolia whereas docetaxel is prepared by hemisynthesis starting from 10-deacetyl-baccatin III, an inactive precursor found in the needles of the European yew tree Taxus baccata. These two drugs are active in various in vitro and in vivo preclinical models (cell lines, cloning of human tumor stem cells, murine grafted tumors, human xenografts). Taxoids constitute a new class of antimitotic agents different from vinca-alkaloids: on the one hand, paclitaxel and docetaxel can be considered as inhibitors of the reaction of depolymerization of microtubules into tubulin; on the other hand, vinca-alkaloids inhibit reaction of polymerization of tubulin into microtubules. An active program of medicine chemistry is done in various pharmaceutical and academic Institutions with two objectives: knowledge of structure-activity relationships and selection of new candidates for clinical trials. PMID:10846536

  7. A Revisiting of Ownership Structures and Capital Structures Relationship: Evidence From East Asian Financial Crisis

    OpenAIRE

    Warokka, Ari; Herrera, Juan Jose Duran

    2011-01-01

    Some previous research findings indicate that the relationship between ownership structure and company performance which is assumed it is influence by the relationship between managers and shareholder of the company. This relationship would have the potential to affect the decision making in an organization which has an impact to company’s value. This purpose of this research is to extend and expand the existing empirical findings by testing the relationship between ownership structure and ...

  8. The Relationship between Residential Property Development and Property Tax generation in Ibadan North, Oyo State

    Directory of Open Access Journals (Sweden)

    Ajayi M. T. A.

    2014-07-01

    Full Text Available This paper examined the relationship between residential property development and property tax generation in Ibadan North Local Government, Oyo State- Nigeria. Data on residential properties within the Local Government for an eleven year period (1999 – 2010 was obtained from the appropriate planning authority, while records of property taxes generated within the same eleven year period was sourced from the taxing authority within the local government. Regression analysis was used to examine the degree and nature of relationship that a change in the number of residential properties will have on the generation of property taxes. Results showed that the actual property tax paid in Ibadan North Local Government Council is being influenced by the number of residential buildings within the council at about 59.3% variation. This implies that a positive variation in the number of residential buildings within the council will lead to a positive variation in the actual property tax generated. Investigation further revealed that this revenue option is however not fully utilized as payments of these taxes are not fully enforced by the taxing authority. It is therefore paramount that the local government seeks for means of improving its tax base through effective property taxation, thus increasing funds available for community development projects such as electrification, road construction, drainages and other essential utilities.

  9. A genetic algorithm for structure-activity relationships: software implementation

    CERN Document Server

    Jantschi, Lorentz

    2009-01-01

    The design and the implementation of a genetic algorithm are described. The applicability domain is on structure-activity relationships expressed as multiple linear regressions and predictor variables are from families of structure-based molecular descriptors. An experiment to compare different selection and survival strategies was designed and realized. The genetic algorithm was run using the designed experiment on a set of 206 polychlorinated biphenyls searching on structure-activity relationships having known the measured octanol-water partition coefficients and a family of molecular descriptors. The experiment shows that different selection and survival strategies create different partitions on the entire population of all possible genotypes.

  10. Relationship between the structural stability with the types and land uses in southeastern Spain

    International Nuclear Information System (INIS)

    Structural stability is one of the most important physical properties and is proposed as an indicator of quality. The aim of this study is to see the possible relationship between this property with soil types and uses of them. In this paper we have selected the Mazarron area based on their environmental characteristics and has taken forty-one topsoil samples, after analysis and study of the relationship between its structural stability with soil types and uses of same, we find a closer relationship in the case of uses that type, so that the natural soil as the percentage of stable aggregates close to 75%, while in soils anthropized this value reaches 44 %. (Author) 6 refs

  11. Introducing Spectral Structure Activity Relationship (S-SAR) Analysis. Application to Ecotoxicology

    OpenAIRE

    Ana-Maria Lacrămă; Putz, Mihai V

    2007-01-01

    A novel quantitative structure-activity (property) relationship model, namely Spectral-SAR, is presented in an exclusive algebraic way replacing the old-fashioned multi-regression one. The actual S-SAR method interprets structural descriptors as vectors in a generic data space that is further mapped into a full orthogonal space by means of the Gram-Schmidt algorithm. Then, by coordinated transformation between the data and orthogonal spaces, the S-SAR equation is given under simple determinan...

  12. The Relationship Communication Structure - Uncertainty Avoidance

    Directory of Open Access Journals (Sweden)

    Doru Alexandru Ple?ea

    2011-11-01

    Full Text Available As today’s society heads towards digitalization, the virtual environment gains a growing importance. Shaping the e-environment in accordance to the real environment in order to favour the activities and processes going to take place there requires a thorough design. However, cultural attributes of reflected inherently by design play a core part in how the information displayed on websites is perceived. The present paper aims to bring a perspective about transposing the proper communication structure into the website design, from the cultural point of view and from genders point of view, as it resulted from a research of Romanian students from Bucharest Academy of Economic Studies

  13. Relationships between chromosome structure and chromosomal aberrations

    Science.gov (United States)

    Eidelman, Yuri; Andreev, Sergey

    An interphase nucleus of human lymphocyte was simulated by the novel Monte Carlo tech-nique. The main features of interphase chromosome structure and packaging were taken into account: different levels of chromatin organisation; nonrandom localisation of chromosomes within a nucleus; chromosome loci dynamics. All chromosomes in a nucleus were modelled as polymer globules. A dynamic pattern of intra/interchromosomal contacts was simulated. The detailed information about chromosomal contacts, such as distribution of intrachromoso-mal contacts over the length of each chromosome and dependence of contact probability on genomic separation between chromosome loci, were calculated and compared to the new exper-imental data obtained by the Hi-C technique. Types and frequencies of simple and complex radiation-induced chromosomal exchange aberrations (CA) induced by X-rays were predicted with taking formation and decay of chromosomal contacts into account. Distance dependence of exchange formation probability was calculated directly. mFISH data for human lymphocytes were analysed. The calculated frequencies of simple CA agreed with the experimental data. Complex CA were underestimated despite the dense packaging of chromosome territories within a nucleus. Possible influence of chromosome-nucleus structural organisation on the frequency and spectrum of radiation-induced chromosome aberrations is discussed.

  14. Tertiary structural propensities reveal fundamental sequence/structure relationships.

    Science.gov (United States)

    Zheng, Fan; Zhang, Jian; Grigoryan, Gevorg

    2015-05-01

    Extracting useful generalizations from the continually growing Protein Data Bank (PDB) is of central importance. We hypothesize that the PDB contains valuable quantitative information on the level of local tertiary structural motifs (TERMs). We show that by breaking a protein structure into its constituent TERMs, and querying the PDB to characterize the natural ensemble matching each, we can estimate the compatibility of the structure with a given amino acid sequence through a metric we term "structure score." Considering submissions from recent Critical Assessment of Structure Prediction (CASP) experiments, we found a strong correlation (R = 0.69) between structure score and model accuracy, with poorly predicted regions readily identifiable. This performance exceeds that of leading atomistic statistical energy functions. Furthermore, TERM-based analysis of two prototypical multi-state proteins rapidly produced structural insights fully consistent with prior extensive experimental studies. We thus find that TERM-based analysis should have considerable utility for protein structural biology. PMID:25914055

  15. Microstructure-mechanical property relationships in modified 3 chrome steels

    International Nuclear Information System (INIS)

    In this paper, the effects of Ni, Mn, Cr and Mo additions to 2.25Cr-1Mo steel have been studied. Microstructural evidence, from analytical transmission electron microscopy studies, is presented to show how these alloy additions modify the continuously cooled bainitic structures; tempering kinetics; and the structures and compositions of the alloy carbides compared to those observed in tempered commercial 2.25Cr-1Mo pressure vessel steels. The results indicate that significant improvements in hydrogen attack resistance and creep rupture properties can be achieved in 3Cr-1Mo-1Ni and 3Cr-1.5Mo steels by microstructural design based on Larson Miller Parameters

  16. Microstructure and thermomechanical properties relationship of segmented thermoplastic polyurethane (TPU)

    Energy Technology Data Exchange (ETDEWEB)

    Frick, Achim, E-mail: achim.frick@htw-aalen.de; Borm, Michael, E-mail: achim.frick@htw-aalen.de; Kaoud, Nouran, E-mail: achim.frick@htw-aalen.de; Kolodziej, Jan, E-mail: achim.frick@htw-aalen.de; Neudeck, Jens, E-mail: achim.frick@htw-aalen.de [Institute of Polymer Science and Processing (iPSP), HTW Aalen (Germany)

    2014-05-15

    Thermoplastic polyurethanes (TPU) are important polymeric materials for seals. In competition with Acrylonitrile butadiene rubbers (NBR), TPU exhibits higher strength and a considerable better abrasion resistance. The advantage of NBR over TPU is a smaller compression set but however TPU excels in its much shorter processing cycle times. Generally a TPU is a block copolymer composed of hard and soft segments, which plays an important role in determining the material properties. TPU can be processed either to ready moulded parts or can be incorporated by multi component moulding, in both cases it shows decent mechanical properties. In the present work, the relationship between melt-process induced TPU morphology and resultant thermo mechanical properties were examined and determined by means of quasi-static tensile test, creep experiment, tension test and dynamical mechanical analysis (DMA). Scanning electron beam microscope (SEM) and differential scanning calorimeter (DSC) were used to study the morphology of the samples. A significant mathematical description of the stress-strain behaviour of TPU was found using a 3 term approach. Moreover it became evident that processing conditions such as processing temperature have crucial influence on morphology as well as short and long-term performance. To be more precise, samples processed at higher temperatures showed a lack of large hard segment agglomerates, a smaller strength for strains up to 250% and higher creep compliance.

  17. Microstructure and thermomechanical properties relationship of segmented thermoplastic polyurethane (TPU)

    Science.gov (United States)

    Frick, Achim; Borm, Michael; Kaoud, Nouran; Kolodziej, Jan; Neudeck, Jens

    2014-05-01

    Thermoplastic polyurethanes (TPU) are important polymeric materials for seals. In competition with Acrylonitrile butadiene rubbers (NBR), TPU exhibits higher strength and a considerable better abrasion resistance. The advantage of NBR over TPU is a smaller compression set but however TPU excels in its much shorter processing cycle times. Generally a TPU is a block copolymer composed of hard and soft segments, which plays an important role in determining the material properties. TPU can be processed either to ready moulded parts or can be incorporated by multi component moulding, in both cases it shows decent mechanical properties. In the present work, the relationship between melt-process induced TPU morphology and resultant thermo mechanical properties were examined and determined by means of quasi-static tensile test, creep experiment, tension test and dynamical mechanical analysis (DMA). Scanning electron beam microscope (SEM) and differential scanning calorimeter (DSC) were used to study the morphology of the samples. A significant mathematical description of the stress-strain behaviour of TPU was found using a 3 term approach. Moreover it became evident that processing conditions such as processing temperature have crucial influence on morphology as well as short and long-term performance. To be more precise, samples processed at higher temperatures showed a lack of large hard segment agglomerates, a smaller strength for strains up to 250% and higher creep compliance.

  18. ODS steel fabrication: relationships between process, microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Oxide Dispersion Strengthened (ODS) steels are promising candidate materials for generation IV and fusion nuclear energy systems thanks to their excellent thermal stability, high-temperature creep strength and good irradiation resistance. Their superior properties are attributed both to their nano-structured matrix and to a high density of Y-Ti-O nano-scale clusters (NCs). ODS steels are generally prepared by Mechanical Alloying of a pre-alloyed Fe-Cr-W-Ti powder with Y2O3 powder. A fully dense bar or tube is then produced from this nano-structured powder by the mean of hot extrusion. The aim of this work was to determine the main parameters of the process of hot extrusion and to understand the link between the fabrication process, the microstructure and the mechanical properties. The material microstructure was characterized at each step of the process and bars were extruded with varying hot extrusion parameters so as to identify the impact of these parameters. Temperature then appeared to be the main parameter having a great impact on microstructure and mechanical properties of the extruded material. We then proposed a cartography giving the microstructure versus the process parameters. Based on these results, it is possible to control very accurately the obtained material microstructure and mechanical properties setting the extrusion parameters. (author)

  19. Electronic Structure, Lattice Dynamics and Thermoelectric Properties of PbTe from First-Principles Calculation

    International Nuclear Information System (INIS)

    The electronic structure and the lattice dynamics of lead telluride (PbTe) are investigated by using the density functional theory. The thermoelectric properties are then calculated using the semi-classical Boltzmann theory. Moreover, the relationships among the thermoelectric properties, the electronic structure and the lattice dynamics are also studied. Some strategies aiming at optimizing the thermoelectric properties are proposed. The related theoretical calculations therefore give a valuable insight on how to further enhance the thermoelectric properties of PbTe

  20. The Relationship between Financial Flexibility and Capital Structure Decisions

    OpenAIRE

    Shanaz Forozan; Roya Darabi; Salah Mohamadi; Ahmad GHasemi

    2013-01-01

    Making decisions about capital structure is one of the most challenging and problematic issues companies face and thereby it is the most crucial decisions companies have to make for their survival. The aim of this study was to investigate the relationship between financial flexibility and capital structure decisions in accepted companies in Tehran Stock Exchange with using Falkner and Wang Model. Results of testing hypothesis which are based on a sample- that is consisted of 82 firms for a pe...

  1. A genetic algorithm for structure-activity relationships: software implementation

    OpenAIRE

    Jantschi, Lorentz

    2009-01-01

    The design and the implementation of a genetic algorithm are described. The applicability domain is on structure-activity relationships expressed as multiple linear regressions and predictor variables are from families of structure-based molecular descriptors. An experiment to compare different selection and survival strategies was designed and realized. The genetic algorithm was run using the designed experiment on a set of 206 polychlorinated biphenyls searching on structu...

  2. Structure-activity relationship of human bone sialoprotein peptides

    OpenAIRE

    Rapuano, Bruce E.; MacDonald, Daniel E.

    2013-01-01

    In the current study, the relationship between the structure of the RGD-containing human bone sialoprotein (hBSP) peptide 278-293 and its attachment activity toward osteoblast-like (MC3T3) cells was investigated. This goal was accomplished by examining the comparative cell attachment activities of several truncated forms of peptide 278-293. Computer modeling of the various peptides was also performed to assess the role of secondary structure in peptide bioactivity. The elimination of the tyro...

  3. Chemical Structure and Properties: A Modified Atoms-First, One-Semester Introductory Chemistry Course

    Science.gov (United States)

    Schaller, Chris P.; Graham, Kate J.; Johnson, Brian J.; Jakubowski, Henry V.; McKenna, Anna G.; McIntee, Edward J.; Jones, T. Nicholas; Fazal, M. A.; Peterson, Alicia A.

    2015-01-01

    A one-semester, introductory chemistry course is described that develops a primarily qualitative understanding of structure-property relationships. Starting from an atoms-first approach, the course examines the properties and three-dimensional structure of metallic and ionic solids before expanding into a thorough investigation of molecules. In…

  4. Fluency, Text Structure, and Retelling: A Complex Relationship

    Science.gov (United States)

    Cohen, Lynn; Krustedt, Rosanne L.; May, Maria

    2009-01-01

    This study examined the relationship between fluency and comprehension, specifically related to the text structures of narration and dialogue. Using descriptive statistics, this investigation first examined fluency and comprehension of three teacher educators and then through action research examined fluency and comprehension of five third grade…

  5. Using Layer-Cake Geology to Illustrate Structural Topographic Relationships.

    Science.gov (United States)

    Wagner, John Robert

    1987-01-01

    Discusses some of the difficulties of visualizing underlying geologic structural patterns by using maps or wooden blocks. Suggests the use of a modified layer cake to show dipping beds, folds, faults and differential erosion, as well as the relationships of stream valleys to outcrop patterns. (TW)

  6. Relationship between structure and ''decorporative'' efficiency in the diphosphonate chemical series

    International Nuclear Information System (INIS)

    Molecular structure of some diphosphonates was studied by topological analysis. The investigated activity was the efficiency of the molecules to remove injected plutonium from the organism, in order to correlate some topological properties of these molecules to their decorporating ability. The studied polyphosphonates have been divided into two families: unprotected and protected compounds. Only unprotected compounds clearly show structure activity relationships. Though structurally different from the rest of the family, LICAM (C) well fits the correlation. An interpretation was that a better efficiency might be related to the branching of the molecules

  7. The textual idea and its relationship to discourse structure

    Directory of Open Access Journals (Sweden)

    Cosmin D?nut BOC?NIAL?

    2000-12-01

    Full Text Available The textual idea could be characterized through a series of either detailing the current form of idea or continuing a previous form of it. Every element of the series has associated a span of the given text that carries it. If we are to relate different spans of text according to relationship between corresponding elements of the series, we will obtain a possible representation of discourse structure. In this paper we take a set of texts and represent their structure in the above manner. The purpose is to give researchers the possibility to asset our manner to represent discourse structure.

  8. A compilation of structural property data for computer impact calculation (5/5)

    International Nuclear Information System (INIS)

    The paper describes structural property data for computer impact calculations of nuclear fuel shipping casks. Four kinds of material data, mild steel, stainless steel, lead and wood are compiled. These materials are main structural elements of shipping casks. Structural data such as, the coefficient of thermal expansion, the modulus of longitudinal elasticity, the modulus of transverse elasticity, the Poisson's ratio and stress and strain relationships, have been tabulated against temperature or strain rate. This volume 5 involve structural property data of wood. (author)

  9. A compilation of structural property data for computer impact calculation (4/5)

    International Nuclear Information System (INIS)

    The paper describes structural property data for computer impact calculations of nuclear fuel shipping casks. Four kinds of material data, mild steel, stainless steel, lead and wood are compiled. These materials are main structural elements of shipping casks. Structural data such as, the coefficient of thermal expansion, the modulus of longitudinal elasticity, the modulus of transverse elasticity, the Poisson's ratio and stress and strain relationships, have been tabulated against temperature or strain rate. This volume 4 involve structural property data of lead. (author)

  10. Molecular Structures and Functional Relationships in Clostridial Neurotoxins

    Energy Technology Data Exchange (ETDEWEB)

    Swaminathan S.

    2011-12-01

    The seven serotypes of Clostridium botulinum neurotoxins (A-G) are the deadliest poison known to humans. They share significant sequence homology and hence possess similar structure-function relationships. Botulinum neurotoxins (BoNT) act via a four-step mechanism, viz., binding and internalization to neuronal cells, translocation of the catalytic domain into the cytosol and finally cleavage of one of the three soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) causing blockage of neurotransmitter release leading to flaccid paralysis. Crystal structures of three holotoxins, BoNT/A, B and E, are available to date. Although the individual domains are remarkably similar, their domain organization is different. These structures have helped in correlating the structural and functional domains. This has led to the determination of structures of individual domains and combinations of them. Crystal structures of catalytic domains of all serotypes and several binding domains are now available. The catalytic domains are zinc endopeptidases and share significant sequence and structural homology. The active site architecture and the catalytic mechanism are similar although the binding mode of individual substrates may be different, dictating substrate specificity and peptide cleavage selectivity. Crystal structures of catalytic domains with substrate peptides provide clues to specificity and selectivity unique to BoNTs. Crystal structures of the receptor domain in complex with ganglioside or the protein receptor have provided information about the binding of botulinum neurotoxin to the neuronal cell. An overview of the structure-function relationship correlating the 3D structures with biochemical and biophysical data and how they can be used for structure-based drug discovery is presented here.

  11. Morphology-property-relationship of thermo-mechanically graded self-reinforced polypropylene composites

    Science.gov (United States)

    Heim, H.-P.; Rohde, B.; Ries, A.

    2014-05-01

    In this paper the relationship between different composite morphologies and their mechanical properties is to be investigated. By manufacturing two different tape-based polypropylene composites in a compression moulding process, four varying degrees of compaction will be generated. The morphological structure is analyzed using confocal laser light microscopy and wet chemically etched specimen cross-sections. The etching process removes the amorphous phase in the polymer, making the macromolecular orientations and superstructures visible in the reinforcement tapes. The findings of the morphological analysis will be transferred to the results of mechanical investigations.

  12. Relationships between structures and performance of SOFC anodes

    DEFF Research Database (Denmark)

    KlemensØ, Trine; Mogensen, Mogens Bjerg

    2006-01-01

    The nickel-YSZ cermet of the state-of-the-art anode-supported solid oxide fuel cell (SOFC) degrades upon redox cycling. The degradation is a critical issue for the commercialization of the technology. Nickel-YSZ cermets with variable composition and microstructure were examined during redox cycling to obtain knowledge of the degradation mechanism, and to identify parameters and characterization tools to improve the cermet. The investigation techniques included direct observations of the microstructure (light microscopy, scanning electron microscopy, environmental scanning electron microscopy, image analysis), bulk measurements (porosity, dilatometry, mechanical properties), measurements of the electrical performance (direct current conductivity, impedance spectroscopy), measurements of the redox kinetics (thermo gravimetric analysis, synchrotron), and application of simple models of the layered system. A model of the redox mechanism on the microstructural level was described. The degradation related to redox cycling was ascribed to a dynamic reorganization of the Ni/NiO phase, when in the reduced state and upon re-oxidation. The redistribution generated fractures in the YSZ matrix, and bulk expansion of the cermet structure upon oxidation. The bulk expansion promoted cracking of the electrolyte. The redistribution of the reduced nickel phase was observed to occur as rounding of the particles, and nickel sintering. The degree of sintering depended on the temperature, the composition of the ceramic component, and possibly on the local porosity. The redistribution of the NiO phase upon oxidation was seen to depend on the kinetics and the local porosity. At higher temperatures the oxide growth involved fragmentation of the particles. At lower temperatures the growth occurred in the form of an external oxide peel. The mechanical strength of the ceramic component was indicated as a technological potential parameter for improving the redox stability. However, considerable strengthening was indicated to be required. Strengthening that will result in a reduction of the bulk expansion upon re-oxidation with a factor of two was estimated. Modification of the cermet composition with additives was indicated as a possibility for improving the redox stability. Significant strengthening and reduction of the nickel sintering were indicated achievable with additives. However, further experimental work will be required to discover the full potential of the application of additives. The future work will be empirically based, or include detailed descriptions of the relationships between microstructural parameters and the cermet bulk properties.

  13. Structure and properties of metals

    International Nuclear Information System (INIS)

    Metals are one of the most widely used types of engineering materials. Some of their properties, e.g. elastic constants, can be directly related to the nature of the metallic bonds between the atoms. On the other hand macro- and microstructural features of metals , such as point defects, dislocations, grain boundaries, and second phase particles, control their yield, flow, and fracture stress. Images of microstructural elements can be obtained by modern imaging techniques. Modern computer aided methods can be further used to obtain a quantitative description of these microstructures. These methods take advantage of the progress made in recent years in the field of image processing, mathematical morphology and quantitative stereology. Quantitative description of the microstructures are used for modelling processes taking place under the action of applied load at a given temperature and test (service) environment. These model considerations can be illustrated on the example of an austenitic stainless steel, which is an important material for power generating and chemical industry. Reports recently published also show that properties of materials can be significantly modified by the effect of free surface. Examples of such situations include environmental effect on the mechanical properties of materials. Data for austenitic stainless steel is used to discuss contribution of the free surface to the mechanical properties of metals. (author) (author)

  14. Structuring strategy and relationships in North American gas markets

    International Nuclear Information System (INIS)

    Duke Energy's experience in strategy development and structuring relationships with other companies were described. Included was a description of their partnership with PanEnergy and Mobil and a merger between PanEnergy and Duke. In developing their growth strategy, Duke Energy was guided by the following considerations: (1) an assessment of the market, (2) the identification of opportunities, (3) a self-assessment, (4) the establishment of goals, and (5) determining strategic alternatives. The advantages and disadvantages of different structuring relationships were reviewed. Duke Energy's approach to Ontario's residential market and their agreement with Alliance Gas Management were also discussed. The goal of the Alliance Gas management agreement was to simplify Alliance's wholesale gas supply management needs and to allow Alliance access to diverse gas supplies. figs

  15. Bank Image Structure: The Relationship to Consumer Behaviour

    Directory of Open Access Journals (Sweden)

    Lukasova Ruzena

    2014-03-01

    Full Text Available This paper presents the results of a study of the relationship between the bank image, its structure as a reflection in the minds of individuals and behavioural tendencies in relation to banks. Attitudinal scales were used to identify the contents of the particular banks’ image. The structure of the image was identified by means of factor analysis. The study found that the respondents’ behavioural tendencies, i.e. their willingness to be a client of or to recommend a particular bank, are related to different content components of particular banks and mainly to respondents’ needs. Based on the results, the study identifies the danger that the results of the bank image analysis can be misinterpreted if the respondents’ relationship to the bank is underestimated.

  16. Structure-dynamics relationship on coherent transport through disordered systems

    OpenAIRE

    Stefano Mostarda; Federico Levi; Diego Prada-Gracia; Florian Mintert & Francesco Rao

    2013-01-01

    Quantum transport is strongly influenced by interference with phase relations that depend sensitively on the scattering medium. Since even small changes in the geometry of the medium can turn constructive interference to destructive, a clear relation between structure and fast, efficient transport is difficult to identify. Here we present a complex network analysis of quantum transport through disordered systems to elucidate the relationship between transport efficiency and ...

  17. Unbalance Quantitative Structure Activity Relationship Problem Reduction in Drug Design

    OpenAIRE

    D. Pugazhenthi; Rajagopalan, S. P.

    2009-01-01

    Problem statement: Activities of drug molecules can be predicted by Quantitative Structure Activity Relationship (QSAR) models, which overcome the disadvantage of high cost and long cycle by employing traditional experimental methods. With the fact that number of drug molecules with positive activity is rather fewer than that with negatives, it is important to predict molecular activities considering such an unbalanced situation. Approach: Asymmetric bagging and feature selection was introduc...

  18. Slope failure at Bukit Antarabangsa, Ampang, Selangor and its relationship to physical soil properties

    International Nuclear Information System (INIS)

    Slope failure which occurred on 6 December 2008 at Bukit Antarabangsa, Ampang Selangor has caused mortalities and loss of properties whereas more than 20 houses were flattened. Prior to slope failure, it was heavily down poured for a few hours that increased the soil saturation and plasticity properties. A total of 10 soil samples were randomly taken from stable and unstable slopes to determine physical soil properties, infiltration rate and their relationship to rainfall pattern. Soils were analyzed in terms of their physical properties; five years (2005-2009) of daily rainfalls were analyzed to determine their relationship to infiltration rate at each sampling station. Infiltration rate is determined by using infiltrometer double ring. Analysis of physical soils properties shows that soil texture was dominated by sandy soil with relatively high percentage of sand. Values of clay dispersion coefficient were relatively stable to very stable from 0.013 % to 11.85 % and organic content from 1.38 % to 2.74 %. Range of porosity was from 50.12 % to 62.31 %, while the average levels of hydraulic conductivity was from level 2 to 5 or relatively slow to fast. Percentage of soil aggregate stability was from 5.12 % to 48.42 % and this value indicates that relative strength of soil mechanical pressure is inversely proportional to the percentage of water content. Soil plasticity value was high to very high but characterized by inactive colloids. Distribution of monthly rainfall wlloids. Distribution of monthly rainfall was from 38 mm to 427 mm. The infiltration rate during sampling time was from 3.0 cm/ hr to 7.0 cm/ hr; but it was expected from 10.94 cm/ hr to 915.05 cm/ hr during slope failures. Overall, it was interpreted that physical soil properties was closely interrelated with slope stability, structure of sandy soil will enhanced soil porosity stage and enhance the infiltration process during heavy rainfall, and finally triggering of slope failure. (author)

  19. Structural relationships in complex hydrides of the late transition metals

    International Nuclear Information System (INIS)

    Literature data on complex hydrides of the late transition metals (groups 7-10), such as the hydrogen storage material Mg2NiH4, are reviewed with respect to order-disorder phase transitions and structural relationships. They are analysed in terms of crystallographic group-subgroup trees and their use in understanding the different crystal structures from a symmetry point of view is demonstrated. New data are presented on the low temperature behaviour of magnesium iridium hydrides and strontium rhodium hydrides studied by powder X-ray diffraction. (orig.)

  20. Relationship between molecular cloud structure and density PDFs

    CERN Document Server

    Stanchev, Orlin; Veltchev, Todor V; Shetty, Rahul

    2013-01-01

    Volume and column density PDFs in molecular clouds are important diagnostics for understanding their general structure. We developed a novel approach to trace the cloud structure by varying the lower PDF cut-off and exploring a suggested mass-density relationship with a power-law index $x^\\prime$. The correspondence of x' as a function of spatial scale to the slope of the high-density PDF tail is studied. To validate the proposed model, we use results from hydrodynamical simulations of a turbulent self-gravitating cloud and recent data on dust continuum emission from the Planck mission.

  1. Structural and mechanical properties of thorium carbide

    Science.gov (United States)

    Aynyas, Mahendra; Pataiya, Jagdeesh; Arya, B. S.; Singh, A.; Sanyal, S. P.

    2015-06-01

    We have investigated the cohesive energies, equilibrium lattice constants, pressure-volume relationship, phase transition pressure and elastic constant for thorium carbide using an interionic potential theory with modified ionic charge, which includes Coulomb screening effect due to d-electrons. This compound undergoes structural phase transition from NaCl (B1) to CsCl (B2) structure at high pressure 40 GPa. We have also calculated bulk, Young, and shear moduli, Poisson ratio and anisotropic ratio in NaCl (B1) structure and compared them with other experimental and theoretical results which show a good agreement.

  2. Structure and Properties of Compressed Borate Glasses

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauer, U.

    While the influence of thermal history on the structure and properties of glasses has been thoroughly studied in the past century, the influence of pressure history has received considerably less attention. In this study, we investigate the pressure-induced changes in structure and properties in a series of borate glasses. Upon isostatic compression, NMR experiments show that the fraction of tetrahedral boron increases, leading to an overall decrease of the molar volume of the network. We correlate these structural changes with changes in elastic moduli from Brillouin scattering experiments, hardness and crack formation from nanoindentation experiments, and overshoot in isobaric heat capacity from DSC experiments at ambient pressure. The influence of the initial boron speciation on the degree of changes in structure and properties will also be discussed.

  3. Relationship between Single Walled Carbon Nanotubes Individual Dispersion Behavior and Properties of Electrospun Nanofibers

    Directory of Open Access Journals (Sweden)

    Haji A.

    2013-09-01

    Full Text Available The dispersion stability behavior of single walled carbon nanotube (SWCNT has important effects on morphological and mechanical properties of SWCNT/polymer composite nanofibers. The relationship of the dispersion conditions with morphological and mechanical characteristics for SWCNT / polyacrylonitrile (PAN / polyvinylpyrrolidone (PVP composite nanofibers have been examined. The SEM and TEM analyses of the nanofibers revealed that the deformation in the nanofiber structures increases with increasing SWCNT concentration. Our data indicate that with increasing the amount of SWCNT (from 0 to 2 wt %, the average nanofiber diameter was increased from 163±19 nm to 307±34 nm. Tensile results showed that only 2 wt % SWCNT loading to the electrospun composite nanofibers gave rise to 10-fold and 3-fold increase in the tensile modulus and tenacity of nanofiber layers, respectively. Essentially, high mechanical properties and uniform morphology of the composite naofibers were found at SWCNT concentration of ~2 wt % due to their stable and individual dispersion.

  4. Structure and properties of metals

    CERN Document Server

    Kurzydlowski, K J

    1999-01-01

    Metals are one of the most widely used types of engineering materials. Some of their properties, e.g. elastic constants, can be directly related to the nature of the metallic bonds between the atoms. On the other hand, macro- and $9 microstructural features of metals, such as point defects, dislocations, grain boundaries, and second phase particles, control their yield, flow, and fracture stress. Images of microstructural elements can be obtained by modern $9 imaging techniques. Modern computer aided methods can be further used to obtain a quantitative description of these microstructures. These methods take advantage of the progress made in recent years in the field of image processing, $9 mathematical morphology and quantitative stereology. Quantitative description of the microstructures are used for modeling processes taking place under the action of applied load at a given temperature and test (service) environment. $9 These model considerations can be illustrated on the example of an austenitic stainless...

  5. Applying quantitative structure–activity relationship approaches to nanotoxicology: Current status and future potential

    International Nuclear Information System (INIS)

    The potential (eco)toxicological hazard posed by engineered nanoparticles is a major scientific and societal concern since several industrial sectors (e.g. electronics, biomedicine, and cosmetics) are exploiting the innovative properties of nanostructures resulting in their large-scale production. Many consumer products contain nanomaterials and, given their complex life-cycle, it is essential to anticipate their (eco)toxicological properties in a fast and inexpensive way in order to mitigate adverse effects on human health and the environment. In this context, the application of the structure–toxicity paradigm to nanomaterials represents a promising approach. Indeed, according to this paradigm, it is possible to predict toxicological effects induced by chemicals on the basis of their structural similarity with chemicals for which toxicological endpoints have been previously measured. These structure–toxicity relationships can be quantitative or qualitative in nature and they can predict toxicological effects directly from the physicochemical properties of the entities (e.g. nanoparticles) of interest. Therefore, this approach can aid in prioritizing resources in toxicological investigations while reducing the ethical and monetary costs that are related to animal testing. The purpose of this review is to provide a summary of recent key advances in the field of QSAR modelling of nanomaterial toxicity, to identify the major gaps in research required to accelerate the use of quantitative structure–activity relationship (QSAR) methods, and to provide a roadmap for future research needed to achieve QSAR models useful for regulatory purposes

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

    Science.gov (United States)

    Kantar, Ersin; Keskin, Mustafa

    2013-11-01

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

  7. Structure and properties of small sodium clusters

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Solov'yov, Andrey V.

    2002-01-01

    We have investigated the structure and properties of small metal clusters using all-electron ab initio theoretical methods based on the Hartree-Fock approximation, density functional theory, and perturbation theory and compared the results of our calculations with the available experimental data and the results of other theoretical work. We have systematically calculated the optimized geometries of neutral and singly charged sodium clusters having up to 20 atoms, their multipole moments (dipole and quadrupole), static polarizabilities, binding energies per atom, ionization potentials, and frequencies of normal vibration modes. Our calculations demonstrate the important role of many-electron correlations in the formation of the electronic and ionic structure of small metal clusters and form a good basis for further detailed study of their dynamic properties, as well as the structure and properties of other atomic cluster systems.

  8. Structural properties of annealed SiOx

    International Nuclear Information System (INIS)

    On the basis of recent results, concerning the quantitative determination of the clustered silicon concentration in substoichiometric silicon oxide layer and based on electron energy loss spectroscopy (EELS) and energy-filtered transmission electron microscopy, in this paper we demonstrate that the structural properties of Si nanoclusters (Si ncs) strongly depend on the technique used for specimen preparation. In particular here we report on annealed SiOx films prepared by plasma enhanced chemical vapour deposition (PECVD) and magnetron sputtering, showing that their structural properties are very different. It is shown that in PECVD films only around 30% of the Si excess agglomerates in clusters while an almost complete agglomeration occurs in sputtered films. These data are explained on the basis of the different initial structural properties of the as-deposited films which become crucial for the subsequent evolution.

  9. Optical properties of the semiconductor quantum structure

    International Nuclear Information System (INIS)

    Optical properties of the quantum structures have been discussed with emphasize of the AlGaN/GaN multiple quantum wells and InAs/GaAs quantum dot structures. We report on a detailed study of low temperature photoluminescence in Al0.07Ga0.93 N/GaN multiple quantum wells. The structures were nominally undoped multiple quantum well grown on sapphire substrate. The structure from discrete well width variations is here resolved in photoluminescence spectra. The results demonstrate that the theoretically estimated fields in this work are consistent with the experimental spectra

  10. The properties of crystals with garnet structure

    International Nuclear Information System (INIS)

    The results of investigations of the elastic and photoelastic properties of a number of garnets crystals obtained by Mandelshtam-Brillouin technique including the data of ultrasonic experiments are represented. The velocity of sound propagation, the character of elastic interaction between ions in the lattice, nature of photon-phonon interaction in garnets is revealed. The mechanical, thermal and acoustooptical properties of garnets are rated using measured elastic and photoelastic data. The obtained results allow to predict a number of important characteristics of crystals with garnet structure and promote the development of materials with given properties. (author)

  11. The Relationship between Financial Flexibility and Capital Structure Decisions

    Directory of Open Access Journals (Sweden)

    Shanaz Forozan

    2013-04-01

    Full Text Available Making decisions about capital structure is one of the most challenging and problematic issues companies face and thereby it is the most crucial decisions companies have to make for their survival. The aim of this study was to investigate the relationship between financial flexibility and capital structure decisions in accepted companies in Tehran Stock Exchange with using Falkner and Wang Model. Results of testing hypothesis which are based on a sample- that is consisted of 82 firms for a period of five years from 2006 to 2011- using multivariate linear regression models as well as panel data method, implied that marginal value of cash is negative in terms of market, i.e. the market is not willing to raise funds and will not evaluate this increase to be positive in funds. Furthermore, findings represent that there is no significant relationship between marginal value of financial flexibility and capital structure decisions of firms and firms would not pay attention to financial flexibility level in their decisions regarding increasing or decreasing debts, which in long term would result in loosing financial flexibility as well as profitable investment opportunities.

  12. Propiedades microbiológicas, clasificación y relación estructura-actividad de cefalosporinas e importancia de las cefalosporinas de cuarta generación MICROBIOLOGICAL PROPERTIES, CLASSIFICATIONS AND STRUCTURE-ACTIVITY RELATIONSHIPS OF CEPHALOSPORINS AND THE IMPORTANCE OF FOURTH GENERATION CEPHALOSPORINS

    Directory of Open Access Journals (Sweden)

    SERGIO MELLA M

    2001-01-01

    Full Text Available Las cefalosporinas son uno de los grupos de mayor importancia dentro de los ß-lactámicos. Existen diversas clasificaciones de estas moléculas, siendo la más utilizada aquella que agrupa a estos compuestos de acuerdo a propiedades estructurales, microbiológicas y desarrollo histórico: primera a cuarta generación. Las cefalosporinas de tercera generación han sido ampliamente utilizadas, pero la emergencia de resistencia bacteriana fundamentalmente derivada de la producción de ß-lactamasas tanto cromosomales como plasmidiales, ha limitado el uso de estos compuestos. Las cefalosporinas de cuarta generación se caracterizan por la presencia de un nitrógeno cuaternario en C3, además de mantener el grupo metoxi-imino aminotiazolil en C7. Presentan una elevada penetración intracelular a través de la membrana externa de bacilos Gram negativos y tienen una baja afinidad por enzimas que degradan cefalos-porinas de tercera generación. Cefepime, una cefalosporina de cuarta generación, demostró una mayor actividad inhibitoria sobre cepas chilenas de Klebsiella pneumoniae y Escherichia coli productoras de ß-lactamasas de espectro extendido, que cefotaxima y ceftazidimaThe cephalosporins are one of the most important types of ß-lactam antibiotics. There are various classifications of these molecules, but the most frecuently used classifies them according to their structures, microbiological properties and historical development: first to fourth generation cephalosporins. Third generation cephalosporins have been extensively used, but the emergence of bacterial resistance, mainly as a consecuence of chromosomal and plasmidial production of ß-lactamases has limited the use of these antibiotics. Fourth generation cephalosporins are characterized by the presence of a cuaternary nitrogen in C3; mantaining the methoxyimino aminothiazolyl in C7. Fourth generation cephalosporins display a high capacity of intracellular penetration through the external membranes of Gram negative rods and a low affinity to enzymes that degrade third generation cephalosporins. Cefepime, a fourth generation cephalosporin, has shown more inhibitory activity against chilean strains of Klebsiella pneumoniae and Escherichia coli that produce extended-spectrum ß-lactamases, than cefotaxime and ceftazidime

  13. Specialists meeting on properties of primary circuit structural materials including environmental effects

    International Nuclear Information System (INIS)

    The Specialists Meeting on Properties of Primary Circuit Structural Materials of LMFBRs covered the following topics: overview of materials program in different countries; mechanical properties of materials in air; fracture mechanics studies - component related activities; impact of environmental influences on mechanical properties; relationship of material properties and design methods. The purpose of the meeting was to provide a forum for exchange of information on structural materials behaviour in primary circuit of fast breeder reactors. Special emphasis was placed on environmental effects such as influence of sodium and irradiation on mechanical properties of reactor materials

  14. Electrochemically Deposited Nickel Membranes; Process-Microstructure-Property Relationships

    DEFF Research Database (Denmark)

    Jensen, Jens Dahl; Pantleon, Karen

    2003-01-01

    This paper reports on the manufacturing, surface morphology, internal structure and mechanical properties of Ni-foils used as membranes in reference-microphones. Two types of foils, referred to as S-type and 0-type foils, were electrochemically deposited from a Watts-type electrolyte, with (S-type) or without (0-type) the use of the sulphur-containing additive sodium saccharin. Both types of Ni-foils appeared perfectly smooth when investigated with scanning electron microscopy (SEM), while atomic force microscopy (AFM) and transmission electron microscopy (TEM), revealed differences in the surface morphologies and a smaller grain-size in the S-type foils. X-ray diffraction showed a texture component in both types of Ni-foils, most pronounced for 0-type foils. A minor -texture component observed in both foil types was strongest in the S-type foils. Mechanically 0-type foils proved more ductile than S-type foils during thin film tensile testing, due to microstructural defects caused by sodium saccharin duringdeposition. Tensile strengths in the order of 700-1000 MPa were observed - highest for the more ductile 0-type foils. A hardness in the order of 6 GPa (590 HV) was found by nanoindentation. Keywords: Nickel; electrodeposition; microstructure; mechanical testing; thin films

  15. Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites

    Directory of Open Access Journals (Sweden)

    Alejandra J. Monsiváis-Barrón

    2014-10-01

    Full Text Available Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes.

  16. Lanthanide acylpyrazolonates: synthesis, properties and structural features

    Science.gov (United States)

    Belousov, Yu A.; Drozdov, Andrey A.

    2012-12-01

    Data concerning synthesis and structural features of lanthanide acylpyrazolonates including tris-complexes, heteroligand complexes with aromatic N-heterocycles and phosphorus-containing ligands and anionic tetrakis-complexes are summarized. The effect of substituents in the acyl moiety on the structural and luminescence properties of the compounds is considered. The key features of acylpyrazolonate coordination polymers and bis(acylpyrazolonates) of rare earth elements are discussed. The bibliography includes 71 references.

  17. Phase relationships, basic metallurgy and superconducting properties of Nb3Sn and related compounds

    International Nuclear Information System (INIS)

    The phase relationships and the superconducting properties of Nb3Sn are compared with those of other high Tsub(c) compounds crystallizing in the A15 structure: Nb3Al, Nb3Ga, Nb3Ge, V3Si, V3Ga ... Characteristic differences of these systems, i.e., the shape of the A15 phase field, the variation of Tsub(c) with composition or with atomic ordering, are discussed. Recent methods leading to the accurate determination of the phase relationships in these systems up to 2000 0C are reviewed. The discussion is extended to the low temperature relationships in Nb3Sn and V3Si with the corresponding tetragonal modifications. Methods for observing these low temperature details and recent results about their influence on Tsub(c) are presented. In the case of Nb3Sn, the factors influencing the formation of the low temperature tetragonal phase, such as hydrostatic pressure, precompression in multifilamentary wires, or hydrogen loading, are discussed. (orig.)

  18. Microstructure, process, and tensile property relationships in an investment cast near-?TiAl alloy

    International Nuclear Information System (INIS)

    The brittle nature of near-? TiAl alloys makes fabrication difficult. This paper reports on developing near-net shape technologies, such as investment casting, for these alloys which is one of the essential approached to their commercial introduction. The near-? TiAl alloy Ti-48Al-2Nb-2Cr (a%) is investment cast with two cooling rates. The effect of casting cooling rate on the fill and surface integrity was studied for complex shape thin walled components. Block and bar castings are hot isostatically pressed (HIP'd) and heat treated to produce duplex (lamellar + equiaxed) microstructures for mechanical property evaluation. The relationships between the casting conditions, microstructures, and tensile properties are studied. The strength and elongation below the ductile to brittle transition temperature are dependent on the casting cooling rate and section size. The tensile properties improved with faster cooling during the casting process as a result of microstructural refinement. Faster cooled castings are more fully transformed to a duplex structure during post-casting heat treatments. Above the ductile to brittle transition temperature the effect of casting cooling rate on tensile properties is less pronounced

  19. The structure?activity relationship in herbicidal monosubstituted sulfonylureas

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zheng-Ming; Ma, Yi; Guddat, Luke; Cheng, Pei-Quan; Wang, Jian-Guo; Pang, Siew S; Dong, Yu-Hui; Lai, Cheng-Ming; Wang, Ling-Xiu; Jia, Guo-Feng; Li, Yong-Hong; Wang, Su-Hua; Liu, Jie; Zhao, Wei-Guang; Wang, Bao-Lei (Nankai); (Queens); (Chinese Aca. Sci.)

    2012-05-24

    The herbicide sulfonylurea (SU) belongs to one of the most important class of herbicides worldwide. It is well known for its ecofriendly, extreme low toxicity towards mammals and ultralow dosage application. The original inventor, G Levitt, set out structure-activity relationship (SAR) guidelines for SU structural design to attain superhigh bioactivity. A new approach to SU molecular design has been developed. After the analysis of scores of SU products by X-ray diffraction methodology and after greenhouse herbicidal screening of 900 novel SU structures synthesized in the authors laboratory, it was found that several SU structures containing a monosubstituted pyrimidine moiety retain excellent herbicidal characteristics, which has led to partial revision of the Levitt guidelines. Among the novel SU molecules, monosulfuron and monosulfuron-ester have been developed into two new herbicides that have been officially approved for field application and applied in millet and wheat fields in China. A systematic structural study of the new substrate-target complex and the relative mode of action in comparison with conventional SU has been carried out. A new mode of action has been postulated.

  20. Exploring the sequence-structure relationship for amyloid peptides.

    Science.gov (United States)

    Morris, Kyle L; Rodger, Alison; Hicks, Matthew R; Debulpaep, Maya; Schymkowitz, Joost; Rousseau, Frederic; Serpell, Louise C

    2013-03-01

    Amyloid fibril formation is associated with misfolding diseases, as well as fulfilling a functional role. The cross-? molecular architecture has been reported in increasing numbers of amyloid-like fibrillar systems. The Waltz algorithm is able to predict ordered self-assembly of amyloidogenic peptides by taking into account the residue type and position. This algorithm has expanded the amyloid sequence space, and in the present study we characterize the structures of amyloid-like fibrils formed by three peptides identified by Waltz that form fibrils but not crystals. The structural challenge is met by combining electron microscopy, linear dichroism, CD and X-ray fibre diffraction. We propose structures that reveal a cross-? conformation with 'steric-zipper' features, giving insights into the role for side chains in peptide packing and stability within fibrils. The amenity of these peptides to structural characterization makes them compelling model systems to use for understanding the relationship between sequence, self-assembly, stability and structure of amyloid fibrils. PMID:23252554

  1. The structure and properties of water

    CERN Document Server

    Eisenberg, David S

    2005-01-01

    The authors have correlated many experimental observations and theoretical discussions from the scientific literature on water. Topics covered include the water molecule and forces between water molecules, the thermodynamic properties of steam, the structures of the ices, hydrogen bonding in ice and water and much more.

  2. Structure, chemistry, and properties of mineral nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Waychunas, G.A.; Zhang, H.; Gilbert, B.

    2008-12-02

    Nanoparticle properties can depart markedly from their bulk analog materials, including large differences in chemical reactivity, molecular and electronic structure, and mechanical behavior. The greatest changes are expected at the smallest sizes, e.g. 10 nm and below, where surface effects are expected to dominate bonding, shape and energy considerations. The precise chemistry at nanoparticle interfaces can have a profound effect on structure, phase transformations, strain, and reactivity. Certain phases may exist only as nanoparticles, requiring transformations in chemistry, stoichiometry and structure with evolution to larger sizes. In general, mineralogical nanoparticles have been little studied.

  3. Structure-function relationship of Vpr: biological implications.

    Science.gov (United States)

    Morellet, Nelly; Roques, Bernard P; Bouaziz, Serge

    2009-03-01

    Vpr, incorporated into the HIV-1 virion, shows multiple activities including nuclear transport of the preintegration complex to the nucleus, activation of the transcription, cell cycle arrest at the G2/M transition and induction of apoptosis. Vpr controls many host cell functions through a variety of biological activities and by interaction with cellular biochemical pathways. Nuclear import of Vpr may be due to its interaction with nuclear transport factors and components of the nuclear pore complex. Cell cycle arrest has been correlated with the binding to DCAF1, a cullin 4A-associated factor and apoptosis may be facilitated by interaction with mitochondrial proteins, in a caspase-dependent mechanism. The structure of Vpr(1-96) and various fragments have been determined by NMR in diverse solvents. The different functions of Vpr can be classified according to their relationship with the different structural domains of the protein and appear to correlate with the partners interacting with these domains. Thus, virion packaging seems to be mediated by the first alpha-helix (17-33), activation of the transcription, regulation of apoptosis and subcellular transport appear to be dependent on the second alpha-helix (38-50) and cell cycle arrest seems to be induced by the carboxyl terminal alpha-helix (55-77). Mutational analysis performed by several groups have provided a strong basis to understand the structure-function relationship of Vpr. The aim of this review is to run through these mutations using the available information on sequences and discuss their effect on the functions of Vpr from the point of view of its structure. PMID:19275588

  4. Propiedades microbiológicas, clasificación y relación estructura-actividad de cefalosporinas e importancia de las cefalosporinas de cuarta generación / MICROBIOLOGICAL PROPERTIES, CLASSIFICATIONS AND STRUCTURE-ACTIVITY RELATIONSHIPS OF CEPHALOSPORINS AND THE IMPORTANCE OF FOURTH GENERATION CEPHALOSPORINS

    Scientific Electronic Library Online (English)

    SERGIO, MELLA M; CLAUDIA, ZEMELMAN M; HELIA, BELLO T; MARIANA, DOMINGUEZ Y; GERARDO, GONZALEZ R; RAUL, ZEMELMAN Z.

    Full Text Available Las cefalosporinas son uno de los grupos de mayor importancia dentro de los ß-lactámicos. Existen diversas clasificaciones de estas moléculas, siendo la más utilizada aquella que agrupa a estos compuestos de acuerdo a propiedades estructurales, microbiológicas y desarrollo histórico: primera a cuart [...] a generación. Las cefalosporinas de tercera generación han sido ampliamente utilizadas, pero la emergencia de resistencia bacteriana fundamentalmente derivada de la producción de ß-lactamasas tanto cromosomales como plasmidiales, ha limitado el uso de estos compuestos. Las cefalosporinas de cuarta generación se caracterizan por la presencia de un nitrógeno cuaternario en C3, además de mantener el grupo metoxi-imino aminotiazolil en C7. Presentan una elevada penetración intracelular a través de la membrana externa de bacilos Gram negativos y tienen una baja afinidad por enzimas que degradan cefalos-porinas de tercera generación. Cefepime, una cefalosporina de cuarta generación, demostró una mayor actividad inhibitoria sobre cepas chilenas de Klebsiella pneumoniae y Escherichia coli productoras de ß-lactamasas de espectro extendido, que cefotaxima y ceftazidima Abstract in english The cephalosporins are one of the most important types of ß-lactam antibiotics. There are various classifications of these molecules, but the most frecuently used classifies them according to their structures, microbiological properties and historical development: first to fourth generation cephalos [...] porins. Third generation cephalosporins have been extensively used, but the emergence of bacterial resistance, mainly as a consecuence of chromosomal and plasmidial production of ß-lactamases has limited the use of these antibiotics. Fourth generation cephalosporins are characterized by the presence of a cuaternary nitrogen in C3; mantaining the methoxyimino aminothiazolyl in C7. Fourth generation cephalosporins display a high capacity of intracellular penetration through the external membranes of Gram negative rods and a low affinity to enzymes that degrade third generation cephalosporins. Cefepime, a fourth generation cephalosporin, has shown more inhibitory activity against chilean strains of Klebsiella pneumoniae and Escherichia coli that produce extended-spectrum ß-lactamases, than cefotaxime and ceftazidime

  5. A validation of the Experiences in Close Relationships-Relationship Structures scale (ECR-RS) in adolescents

    DEFF Research Database (Denmark)

    Donbaek, Dagmar Feddern; Elklit, Ask

    2014-01-01

    Emerging evidence points toward a two-dimensional attachment construct: avoidance and anxiety. The Experiences in Close Relationships-Relationship Structures scale (ECR-RS; Fraley, Heffernan, Vicary, & Brumbaugh, 2011) is a questionnaire assessing two-dimensional relationship-specific attachment structures in adults and, hence, moves beyond the traditional focus on romantic relationships. The present article explored the psychometric abilities of the ECR-RS across parental and best friend domains in a sample of 15 to 18-year-olds (n = 1999). Two oblique factors were revealed across domains, exhibiting satisfactory construct validity, including factorspecific links to the model of adult attachment (Bartholomew & Horowitz, 1991), and independent factor discrimination between subgroups. A robust validation supports the application of the ECR-RS to assessing relationship-specific adolescent attachment structures.

  6. Microstructure and mechanical properties: Direct and inverse relationships (Invited)

    Science.gov (United States)

    Evans, B.

    2009-12-01

    Understanding the relations between the mechanical properties of rocks and the elements of rock microstructure, including grain size, preferred lattice orientation, and the geometry of phase distributions, is critical for developing robust mechanical constitutive laws. Conversely, the analysis of microstructure within a rock mass is a time-honored technique from structural geology used to unravel the history of natural deformation. These two approaches can be viewed as direct and inverse determinations of natural geomechanics; taken together they should constitute a full and consistent description. Some elements of microstructure have been suggested to be mechanical state variables that might achieve dynamically stable values under certain loading conditions, e.g. recrystallized grain size, dislocation density, or sub-grain size, while other elements of structure may be strongly dependent on history and evolve over much longer periods of time and strain, e.g. LPO or other fabric elements. The former class would be valuable in indicating thermodynamic variables occurring during deformation, perhaps stress or work rate, and the latter would be useful in understanding natural strain paths. Several questions that are important, remain at least partially unresolved: Which mechanical state variables are most critical for the determination of strength; which may be said to be rate-controlling, and under what thermodynamic conditions? How do the important state variables interrelate and by what mechanisms and at what rates do they evolve? (The latter question is pertinent to questions of stability and weakening.) As an example of the evolution of state variables, we investigated grain-size changes in synthetic and natural marbles, suggesting that the rate of evolution could be scaled by the rate of mechanical work being done on the rock. Other treatments of the same problem, however, emphasize the influence of single variable, like differential stress, or alternatively, postulate more detailed kinetic relations for fundamental processes, like boundary nucleation or sub-grain formation. Finally, for low strain deformation, recent experiments show that spatial variations in the local strain field can be as large as 2 or 3 times that of the bulk strain. Can one expect a uniform dynamically stable distribution of stresses and strain rates to obtain in a poly-crystal after a characteristic interval of strain? If so, does the variance of the distribution change with thermodynamic conditions? And, can an analysis of these distributions and variations provide a useful technique to analyze natural deformations?

  7. Structure-molluscicidal activity relationships of acylphloroglucinols from ferns.

    Science.gov (United States)

    Socolsky, Cecilia; Borkosky, Susana; Bardón, Alicia

    2011-03-01

    The molluscicidal activity of 12 phloroglucinol derivatives previously isolated from Elaphoglossum piloselloides, E. gayanum, E. yungense, and E. lindbergii, as well as 3 known acylphloroglucinols, now reported from an Argentine collection of Dryopteris wallichiana, was evaluated against the schistosomiasis vector snail Biomphalaria peregrina. Molluscicidal effects were analyzed and compared with those previously observed for 4 acylphloroglucinols from E. piloselloides and their corresponding peracetylated derivatives, in order to draw structure-activity relationships. The most active compounds were the prenylated desaspidins elaphogayanin B and elaphopilosins A and B (LD50 = 1.90, 2.90, and 0.94 ppm, respectively), together with the only evaluated prenylated para-aspidin, elaphopilosin C (LD50 = 2.15 ppm). Quantitative structure-activity relationships (QSAR) were studied by means of a semiempirical method (PM3) for the 24 natural phloroglucinol derivatives included in this paper. The descriptor molecular volume was found to have good correlation with the observed molluscicidal activity (r2 = 0.77). The derived equation can be considered useful to predict the molluscicidal activity of bi and tricyclic acylphloroglucinols. The QSAR analysis showed that there is an optimum volume for high activity, probably related to the size of a receptor's active site. Bigger molecules display lower activity. PMID:21485280

  8. MASPROP- MASS PROPERTIES OF A RIGID STRUCTURE

    Science.gov (United States)

    Hull, R. A.

    1994-01-01

    The computer program MASPROP was developed to rapidly calculate the mass properties of complex rigid structural systems. This program's basic premise is that complex systems can be adequately described by a combination of basic elementary structural shapes. Thirteen widely used basic structural shapes are available in this program. They are as follows: Discrete Mass, Cylinder, Truncated Cone, Torus, Beam (arbitrary cross section), Circular Rod (arbitrary cross section), Spherical Segment, Sphere, Hemisphere, Parallelepiped, Swept Trapezoidal Panel, Symmetric Trapezoidal Panels, and a Curved Rectangular Panel. MASPROP provides a designer with a simple technique that requires minimal input to calculate the mass properties of a complex rigid structure and should be useful in any situation where one needs to calculate the center of gravity and moments of inertia of a complex structure. Rigid body analysis is used to calculate mass properties. Mass properties are calculated about component axes that have been rotated to be parallel to the system coordinate axes. Then the system center of gravity is calculated and the mass properties are transferred to axes through the system center of gravity by using the parallel axis theorem. System weight, moments of inertia about the system origin, and the products of inertia about the system center of mass are calculated and printed. From the information about the system center of mass the principal axes of the system and the moments of inertia about them are calculated and printed. The only input required is simple geometric data describing the size and location of each element and the respective material density or weight of each element. This program is written in FORTRAN for execution on a CDC 6000 series computer with a central memory requirement of approximately 62K (octal) of 60 bit words. The development of this program was completed in 1978.

  9. Structure and properties of rediation crosslinked LDPE-EPDM blends

    International Nuclear Information System (INIS)

    The regularity of radiation crosslinking and the radiation effect on the structure and property of LDPE (low density polyethylene)-EPDM (copolymer of ethylene-propylene)blends are reported in this paper. The results show that radiation crosslinking effect on LDPE/EPDM blends is either similar to pure LDPE or EPDM, depending upon which one is the main component in the blends. When the content of LDPE is higher than that of EPDM crosslinking of the blend is close to pure LDPE. The relationship between S+S1/2 and 1/R does not comply with Charlesby-Pinner's equation. While for blends rich in EPDM, a linear relationship is observed at high doses. The higher the content of EPDM in the blend, the easier is the blend to be crosslinked because of the presence of unsaturated bond in EPDM. The crystaline extent and density of the blend increases with increasing LDPE content in the blends. No obvious change of crystaline extent is observed in the dose range used. There is a close relationship between mechanical property and composition of the blends. The tensile strength (Ts) increases with increase in LDPE content, whereas the elongation (E%) shows a reverse effect. The effect of radiation dose on Ts is insignificant. However the elongation (E%) is seriousely affected

  10. Relationships between Conversion, Temperature and Optical Properties during Composite Photopolymerization

    OpenAIRE

    Howard, Benjamin; Wilson, Nicholas D.; Newman, Sheldon M.; Pfeifer, Carmem S.; Stansbury, Jeffrey W.

    2009-01-01

    Optical properties of composite restoratives, both cured and uncured, are of obvious importance in a procedure reliant on photoactivation, since they may affect light transmission and therefore, materials conversion upon which mechanical properties and ultimate clinical performance are dependent. The objective of the present study was to evaluate simultaneous, real-time conversion, temperature and optical properties development. The dimethacrylate resin (BisGMA / TEGDMA 70/30 mass %) was prep...

  11. ???????????????? Regression Analysis on the Relationship between Water Consumption Structure and Industrial Structure in Fujian Province

    Directory of Open Access Journals (Sweden)

    ???

    2012-06-01

    Full Text Available ??????????????????????????????????????????????????logratio??????????(PLS??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ? ???? ? ????? Prediction of water consumption structure on the basis of the relationship between water consumption structure and industrial structure is essential to the exploitation and utilization of water resources. Based on the symmetrical logratio transformation and partial least-squares regression, linear regression model for water consumption structure and industrial structure in FujianProvinceis developed in this study. Analysis on the model showed that the compositional data of water consumption structure and industrial structure inFujianProvincehad obvious linear relationship. This model fit the data very well with high accuracy and can be used to predict water consumption structure. Agricultural water was highly correlated with primary industry, and so was the industrial water with secondary industry. Agricultural water showed significantly negative correlation with secondary industry and tertiary industry. The variation of domestic water had an insignificant correlation with industrial structure. The capacity to explain water consumption structure of the industrial structure factors was in the order of primary industry > secondary industry > tertiary industry.

  12. Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska

    OpenAIRE

    Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-sun; Chun, Jongsik; Lee, Yoo Kyung

    2014-01-01

    The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil s...

  13. Physicochemical properties of bile acids and their relationship to biological properties: an overview of the problem.

    Science.gov (United States)

    Hofmann, A F; Roda, A

    1984-12-15

    The structure of the bile acid molecule is described and correlated with physiochemical properties of bile acids such as solubility, ionization, and micelle formation. Recent measurements of the critical micellar concentration (CMC) of a large number of bile acids indicate that the CMC is influenced by both side chain and nuclear structure. Bile acids with hydroxy substituents on both sides of the steroid nucleus are non-amphipathic and do not form micelles, and decreasing the length of the side chain causes an exponential increase in the CMC. Bile acid ionization, measured by titration in alcohol-water mixtures, is shown to be uninfluenced by nuclear substituents; the pKa of all unconjugated bile acids is about 5. Interactions of bile acid solutions with Ca2+ are discussed; recent work indicates that cholyl conjugates bind Ca2+ as monomers in solution. Model systems relevant to biological processes are classified, as are some of the physicochemical parameters of these systems. Biological processes involving bile acids are tabulated, and corresponding model systems are assigned to each. Some biological processes such as bile acid transport show marked species differences, suggesting that physicochemical parameters are insufficient to explain biological differences. It is recommended that the physical chemist study a variety of bile acids, that the biologist study a variety of species, and that both collaborate to attempt to factor out the extent to which physicochemical properties of bile acids can explain their biological properties. PMID:6397555

  14. Unravelling the materials genome: Symmetry relationships in alloy properties

    International Nuclear Information System (INIS)

    Highlights: ? Research strategy for Accelerated Metallurgy project is outlined. ? Surprising symmetry among atomic, nanoscale and mechanical properties. ? Generalisation of Ashby diagrams via principal component analysis. ? Atomic-related properties can be described with linear regression. ? Mechanical properties modelled via Kocks–Mecking-type physical method. -- Abstract: Metals and alloys have been indispensable for technological progress, but only a fraction of the possible ternary systems (combinations of three elements) is known. Statistical inference methods combined with physical models are presented to discover new systems of enhanced properties. It is demonstrated that properties originating from atomic-level interactions can be described employing a linear regression analysis, but properties incorporating microstructural and thermal history effects require a balance between physical and statistical modelling. In spite of this, there is a remarkable degree of symmetry among all properties, and by employing a principal components analysis it is shown that ten properties essential to engineering can be described well in a three dimensional space. This will aid in the discovery of novel alloying systems

  15. Synthesis and structure-activity relationships of novel benzoxaboroles as a new class of antimalarial agents.

    Science.gov (United States)

    Zhang, Yong-Kang; Plattner, Jacob J; Freund, Yvonne R; Easom, Eric E; Zhou, Yasheen; Gut, Jiri; Rosenthal, Philip J; Waterson, David; Gamo, Francisco-Javier; Angulo-Barturen, Inigo; Ge, Min; Li, Zhiya; Li, Lingchao; Jian, Yong; Cui, Han; Wang, Hailong; Yang, Jian

    2011-01-15

    A series of boron-containing benzoxaborole compounds was designed and synthesized for a structure-activity relationship investigation surrounding 7-(HOOCCH(2)CH(2))-1,3-dihydro-1-hydroxy-2,1-benzoxaborole (1) with the goal of discovering a new antimalarial treatment. Compound 1 demonstrates the best potency (IC(50)=26nM) against Plasmodium falciparum and has good drug-like properties, with low molecular weight (206.00), low ClogP (0.86) and high water solubility (750?g/mL at pH 7). PMID:21195617

  16. Progress in Studies on Rutaecarpine. II.-Synthesis and Structure-Biological Activity Relationships.

    Science.gov (United States)

    Son, Jong-Keun; Chang, Hyeun Wook; Jahng, Yurngdong

    2015-01-01

    Rutaecarpine is a pentacyclic indolopyridoquinazolinone alkaloid found in Evodia rutaecarpa and other related herbs. It has a variety of intriguing biological properties, which continue to attract the academic and industrial interest. Studies on rutaecarpine have included isolation from new natural sources, development of new synthetic methods for its total synthesis, the discovery of new biological activities, metabolism, toxicology, and establishment of analytical methods for determining rutaecarpine content. The present review focuses on the synthesis, biological activities, and structure-activity relationships of rutaecarpine derivatives, with respect to their antiplatelet, vasodilatory, cytotoxic, and anticholinesterase activities. PMID:26111170

  17. Definition and properties of ideal amorphous structures

    International Nuclear Information System (INIS)

    Full text: Amorphous structure is usually defined by what it is not (ie, no crystalline peaks in XRS, no bond correlation in NMR), rather than by what it is. The interest in defining the structure of non-crystalline materials is long standing; packing geometry of spheres, molecular structure of glassy SiO2, or the structure of atactic polymers are prime examples. The earliest definitions of amorphous structure were in terms of a microcrystallite model of Valenkov, or continuous random network by Zachariasen. The random close packing of spheres of equal size, and an amorphous structure, composed of freely jointed linear chains of hard spheres, has been described mathematically in terms of a linear homogeneous Poisson process. This paper aims to describe some geometrical, kinematic, and topological properties of these two ideal amorphous structures, which belong to the same amorphous class. The geometry of packing is elucidated, and the use of Voronoi tessellation method for measuring the structures is described. The ideal amorphous solid has no symmetry elements; its volume can not be divided into identical unit cells. However, there is a volume element small enough to allow the distinction of its nanoscopic inhomogeneities, and sufficiently large enough to represent, accurately the overall behaviour. We define this volume element, the representative volume element. Suitable boundary conditions must be prescribed for a choice of RVE, and satisfy certain requ a choice of RVE, and satisfy certain requirements. Topologically, a catchment region on the Born-Oppenheimer potential energy surface over nuclear configuration space, is defined by Mezey and Bader as an energetically stable geometry of the open region of R3 traversed by all the trajectories which terminate at a local maximum. Two topological properties will be described: (i) the boundaries of the catchment region as a direct geometrical correspondence to the Voronoi polyhedron for a given atom in a given structure, and (ii) the constriction points, described previously, as an inherent characteristic of IAS type II (and possibly others)

  18. Nucleon structure and properties of dense matter

    International Nuclear Information System (INIS)

    We consider the properties of dense matter in a framework of the Skyrme soliton model and the chiral bag model. The influence of the nucleon structure on the equation of state of dense matter is emphasized. We find that in both models the energy per unit volume is proportional to n4/3, n being the baryon number density. We discuss the properties of neutron stars with a derived equation of state. The role of many-body effects is investigated. The effect of including higher order terms in the chiral lagrangian is examined. The phase transition to quark matter is studied. 29 refs., 6 figs. (author)

  19. Structure and magnetic properties of powder HITPERM material

    Directory of Open Access Journals (Sweden)

    J.E. Fr?ckowiak

    2007-03-01

    Full Text Available Purpose: The aim of the work is to investigate the structure and magnetic properties of the cobalt based HITPERM amorphous alloy Co68Fe4Mo1Si13.5B13.5 subjected high-energy ball milling and to the isothermal annealing to a combination of these two technologies.Design/methodology/approach: The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses ribbons in as state. Using the HFQS program the distributions of the magnetic hyperfine P(H fields were determined for spectra smoothed in this way, employing the Hesse-Rübartsch method. Observations of the structure of powders were made on the OPTON DSM-940 scanning electron microscope. The diffraction examinations and examinations of thin foils were made on the JEOL JEM 200CX transmission electron microscope equipped in equipped with the EDS LINK ISIS X- ray energy dispersive spectrometer made by Oxford. Graphical analyses of the obtained X-ray diffraction patterns, as well as of the HC=f(TA relationship were made using the MICROCAL ORIGIN 6.0 program.Findings: The analysis of the structure and magnetic properties test results of the HITPERM powders alloy Co68Fe4Mo1Si13.5B13.5 obtained in the high-energy ball of milling process proved that the process causes significant decrease in the magnetic properties. The magnetic properties of this material and structure and may be improved by means of a proper choice of parameters of this process as well as the final thermal treatment.Research limitations/implications: For the soft magnetic powder material, further magnetical, composition examinations and structure are planed.Practical implications: Feature an alternative to solid alloys are the amorphous and nanocrystalline metal powders obtained by milling of metallic glasses and make it possible to obtain the ferromagnetic nanocomposites, whose dimensions and shape can be freely formed.Originality/value: The paper presents results of influence of parameters of the high-energy ball milling process on magnetic properties and structure of soft magnetic powder HITPERM alloy obtained in this technique. The paper compares magnetic properties and structure of the HITPERM alloy obtained in high-energy ball milling process, melt spinning technique and in a combination of these two technologies.

  20. Cryptocaryol A and B: Total Syntheses, Stereochemical Revision, Structure Elucidation and Structure-Activity Relationship

    OpenAIRE

    Wang, Yanping; O’Doherty, George A.

    2013-01-01

    The first total syntheses and structural elucidation of cryptocaryol A and cryptocaryol B were achieved in 23 and 25 linear steps, respectively. The synthesis relied on the use of a key pseudo-Cs symmetric pentaol intermediate, which in a stereo-chemically divergent manner was converted into either enantiomer as well as diastereomers. This synthetic effort enabled the first structure-activity relationships of this class of PDCD4 stabilizing natural products.

  1. Structure and Antioxidant Activity Relationships of Isoflavonoids from Dalbergia parviflora

    Directory of Open Access Journals (Sweden)

    Worrawat Promden

    2014-02-01

    Full Text Available The antioxidant activities of 24 isoflavonoids that were previously isolated as pure compounds from Dalbergia parviflora were evaluated using three different in vitro antioxidant-based assay systems: xanthine/xanthine oxidase (X/XO, ORAC, and DPPH. The isolates consisted of three subgroups, namely isoflavones, isoflavanones, and isoflavans, each of which appeared to have diversified substituents, and were thus ideal for the study of their structure-activity relationships (SARs. The SAR analysis was performed using the results obtained from both the inter-subgroup isoflavonoids with the same substitution pattern and the intra-subgroup compounds with different substitution patterns. The inter-subgroup comparison showed that the isoflavones exhibited the highest antioxidant activities based on all three assays. The intra-subgroup analysis showed that the additional presence of an OH group in Ring B at either R3? or R5? from the basic common structure of the R7-OH of Ring A and the R4?-OH (or -OMe of Ring B greatly increased the antioxidant activities of all of the isoflavonoid subgroups and that other positions of OH and OMe substitutions exerted different effects on the activities depending on the subgroup and assay type. Therefore, based on the structural diversity of the isoflavonoids in D. parviflora, the present study provides the first clarification of the detailed antioxidant SARs of isoflavonoids.

  2. 43 CFR 12.937 - Property trust relationship.

    Science.gov (United States)

    2010-10-01

    ...Office of the Secretary of the Interior ADMINISTRATIVE AND AUDIT REQUIREMENTS AND COST PRINCIPLES FOR ASSISTANCE PROGRAMS ...liens or other appropriate notices of record to indicate that personal or real property has been acquired or improved with...

  3. Relationship between the structural and magnetic properties of the series RFe10.5Mo1.5Xx with X=H, C, N and 0?x?1

    International Nuclear Information System (INIS)

    The cell parameter expansions and the atom positions in the crystal structure of the RFe10.5Mo1.5Xx series (X=H, C, N; 0?x?1) depend strongly on the nature, size and concentration of interstitial elements. Magnetic measurements reveal direct correlations between the Curie temperature, the increase in magnetisation and the crystal structure modifications. The change in the magnetocrystalline anisotropy is found to be dependent on the nature of X. (orig.)

  4. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes, E.

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ?110? direction showing the smallest decay with length and the largest conductance and current.

  5. Structure and properties of undercooled liquid metals

    Science.gov (United States)

    Egry, I.; Lohöfer, G.; Gorges, E.; Jacobs, G.

    1996-11-01

    Electromagnetic levitation is a useful tool to process high-temperature and highly reactive melts without a container. It provides a pure environment and contamination of the melt is reduced to a minimum. With the application of non-contact measurement techniques, structures and properties of pure samples can be investigated. One major advantage of this approach is that it allows one access to the metastable state of the undercooled melt. This paper reports on measurements of thermophysical properties of undercooled liquid metals and recent investigations of their structure. We have performed measurements of the surface tension, electrical conductivity, density and thermal expansion of a number of pure metals and alloys. Some experiments were performed under microgravity conditions which reduce the strength of the required electromagnetic fields by orders of magnitude and lead to a much higher precision. We have recently used electromagnetic levitation in combination with synchrotron radiation to obtain EXAFS spectra of an undercooled Co - Pd alloy.

  6. Structure activity relationship of selective GABA uptake inhibitors

    DEFF Research Database (Denmark)

    Vogensen, Stine B; JØrgensen, Lars

    2015-01-01

    A series of ?-amino acids with lipophilic diaromatic side chain was synthesized and characterized pharmacologically on mouse ?-amino butyric acid (GABA) transporter subtypes mGAT1-4 in order to investigate structure activity relationships (SAR) for mGAT2 (corresponding to hBGT-1). Variation in the lipophilic diaromatic side chain was probed to understand the role of the side chain for activity. This yielded several selective compounds of which the best (1R,2S)-5a was more than 10 fold selective towards other subtypes, although potency was moderate. A docking study was performed to investigate possible binding modes of the compounds in mGAT2 suggesting a binding mode similar to that proposed for Tiagabine in hGAT1. Specific interactions between the transporter and the amino acid part of the ligands may account for a reverted preference towards mGAT2 over mGAT1.

  7. Structure activity relationship of selective GABA uptake inhibitors.

    Science.gov (United States)

    Vogensen, Stine B; Jørgensen, Lars; Madsen, Karsten K; Jurik, Andreas; Borkar, Nrupa; Rosatelli, Emiliano; Nielsen, Birgitte; Ecker, Gerhard F; Schousboe, Arne; Clausen, Rasmus P

    2015-05-15

    A series of ?-amino acids with lipophilic diaromatic side chain was synthesized and characterized pharmacologically on mouse ?-amino butyric acid (GABA) transporter subtypes mGAT1-4 in order to investigate structure activity relationships (SAR) for mGAT2 (corresponding to hBGT-1). Variation in the lipophilic diaromatic side chain was probed to understand the role of the side chain for activity. This yielded several selective compounds of which the best (1R,2S)-5a was more than 10 fold selective towards other subtypes, although potency was moderate. A docking study was performed to investigate possible binding modes of the compounds in mGAT2 suggesting a binding mode similar to that proposed for Tiagabine in hGAT1. Specific interactions between the transporter and the amino acid part of the ligands may account for a reverted preference towards mGAT2 over mGAT1. PMID:25882526

  8. Adiposity is associated with structural properties of the adolescent brain.

    Science.gov (United States)

    Schwartz, Deborah H; Dickie, Erin; Pangelinan, Melissa M; Leonard, Gabriel; Perron, Michel; Pike, G Bruce; Richer, Louis; Veillette, Suzanne; Pausova, Zdenka; Paus, Tomáš

    2014-12-01

    Obesity, a major risk factor for cardiometabolic disease, is associated with variations in a number of structural properties in the adult brain, as assessed with magnetic resonance imaging (MRI). In this study, we investigated the cross-sectional relationship between visceral fat (VF), total body fat (TBF) and three MRI parameters in the brains of typically developing adolescents: (i) T1-weighted (T1W) signal intensity; (ii) T1W signal contrast between white matter (WM) and gray matter (GM); and (iii) magnetization transfer ratio (MTR). In a community-based sample of 970 adolescents (12-18 years old, 466 males), VF was quantified using MRI, and total body fat was measured using a multifrequency bioimpedance. T1W images of the brain were used to determine signal intensity in lobar GM and WM, as well as WM:GM signal contrast. A magnetization transfer (MT) sequence of MT(ON) and MT(OFF) was used to obtain MTR in GM and WM. We found that both larger volumes of VF and more TBF were independently associated with higher signal intensity in WM and higher WM:GM signal contrast, as well as higher MTR in both GM and WM. These relationships were independent of a number of potential confounders, including age, sex, puberty stage, household income and height. Our results suggest that both visceral fat and fat deposited elsewhere in the body are associated independently with structural properties of the adolescent brain. We speculate that these relationships suggest the presence of adiposity-related variations in phospholipid composition of brain lipids. PMID:25255944

  9. Unbalance Quantitative Structure Activity Relationship Problem Reduction in Drug Design

    Directory of Open Access Journals (Sweden)

    D. Pugazhenthi

    2009-01-01

    Full Text Available Problem statement: Activities of drug molecules can be predicted by Quantitative Structure Activity Relationship (QSAR models, which overcome the disadvantage of high cost and long cycle by employing traditional experimental methods. With the fact that number of drug molecules with positive activity is rather fewer than that with negatives, it is important to predict molecular activities considering such an unbalanced situation. Approach: Asymmetric bagging and feature selection was introduced into the problem and Asymmetric Bagging of Support Vector Machines (AB-SVM was proposed on predicting drug activities to treat unbalanced problem. At the same time, features extracted from structures of drug molecules affected prediction accuracy of QSAR models. Hybrid algorithm named SPRAG was proposed, which applied an embedded feature selection method to remove redundant and irrelevant features for AB-SVM. Results: Numerical experimental results on a data set of molecular activities showed that AB-SVM improved AUC and sensitivity values of molecular activities and SPRAG with feature selection further helps to improve prediction ability. Conclusion: Asymmetric bagging can help to improve prediction accuracy of activities of drug molecules, which could be furthermore improved by performing feature selection to select relevant features from the drug.

  10. Effect of Weave Structure on Thermo-Physiological Properties of Cotton Fabrics

    Directory of Open Access Journals (Sweden)

    Ahmad Sheraz

    2015-03-01

    Full Text Available This paper aims to investigate the relationship between fabric weave structure and its comfort properties. The two basic weave structures and four derivatives for each selected weave structure were studied. Comfort properties, porosity, air permeability and thermal resistance of all the fabric samples were determined. In our research the 1/1 plain weave structure showed the highest thermal resistance making it suitable for cold climatic conditions. The 2/2 matt weave depicted the lowest thermal resistance which makes it appropriate for hot climatic conditions.

  11. A compilation of structural property data for computer impact calculation (2/5)

    International Nuclear Information System (INIS)

    The paper describes structural property data for computer impact calculations of nuclear fuel shipping casks. Four kinds of material data, mild steel, stainless steel, lead and wood are compiled. These materials are main structural elements of shipping casks. Structural data such as, the coefficient of thermal expansion, the modulus of longitudinal elasticity, the modulus of transverse elasticity, the Poisson's ratio and stress and strain relationships, have been tabulated against temperature or strain rate. This volume 2 involve structural property data of mild steel. (author)

  12. A compilation of structural property data for computer impact calculation (3/5)

    International Nuclear Information System (INIS)

    The paper describes structural property data for computer impact calculations of nuclear fuel shipping casks. Four kinds of material data, mild steel, stainless steel, lead and wood are compiled. These materials are main structural elements of shipping casks. Structural data such as, the coefficient of thermal expansion, the modulus of longitudinal elasticity, the modulus of transverse elasticity, the Poisson's ratio and stress and strain relationships, have been tabulated against temperature or strain rate. This volume 3 involve structural property data of stainless steel. (author)

  13. Correlação entre propriedades mecânicas e parâmetros estruturais de poliuretanos à base de poli(épsilon-caprolactona) / Relationships between mechanical properties and structural parameters of polyurethanes containing poly(epsilon-caprolactone)

    Scientific Electronic Library Online (English)

    Juliana, Kloss; Caroline, Bugay; Leni, Akcelrud; Sônia F., Zawadzki; Shu-Hui, Wang.

    2005-03-01

    Full Text Available No presente trabalho foram preparados poliuretanos (PUs) segmentados. Primeiramente foi obtido um pré-polímero (PP) a partir da reação de 2,4 e 2,6 - diisocianato de tolileno (TDI) e poli(épsilon-caprolactona) diol (PCL). A PCL é um poliéster biodegradável que constituiu o segmento flexível do PU. O [...] segmento rígido foi constituído por unidades uretânicas provenientes da ligação entre as extremidades isocianato do PP e as hidroxilas do extensor de cadeia: 1,4 - butanodiol (BDO), ou sacarose (SAC), ou glicose (GLY). Foram avaliadas as propriedades mecânicas e dinâmico-mecânicas dos poliuretanos obtidos e estas foram correlacionadas com os parâmetros estruturais. Os resultados foram justificados com base na intensidade das interações de hidrogênio, na mistura de fases, no volume dos extensores cíclicos e na presença de ligações cruzadas. Estes PUs estão sendo estudados com vistas à preparação de materiais biodegradáveis com propriedades mecânicas úteis. Abstract in english Segmented polyurethanes containing polycaprolactone as soft segment were prepared taking into account the biodegradable character of this compound. The hard block was produced by the reaction between tolylene diisocyanate and a chain extender (1,4 butanediol, sucrose or glucose). The mechanical and [...] dynamical properties were evaluated as a function of the contents of rigid blocks. The results were analyzed on the basis of the intermolecular interactions, mainly H bonds, phase mixture, volume of cyclic chain extenders and crosslinking. These polyurethanes are being studied aiming at the preparation of biodegradable materials with useful mechanical properties.

  14. Correlação entre propriedades mecânicas e parâmetros estruturais de poliuretanos à base de poli(épsilon-caprolactona Relationships between mechanical properties and structural parameters of polyurethanes containing poly(epsilon-caprolactone

    Directory of Open Access Journals (Sweden)

    Juliana Kloss

    2005-03-01

    Full Text Available No presente trabalho foram preparados poliuretanos (PUs segmentados. Primeiramente foi obtido um pré-polímero (PP a partir da reação de 2,4 e 2,6 - diisocianato de tolileno (TDI e poli(épsilon-caprolactona diol (PCL. A PCL é um poliéster biodegradável que constituiu o segmento flexível do PU. O segmento rígido foi constituído por unidades uretânicas provenientes da ligação entre as extremidades isocianato do PP e as hidroxilas do extensor de cadeia: 1,4 - butanodiol (BDO, ou sacarose (SAC, ou glicose (GLY. Foram avaliadas as propriedades mecânicas e dinâmico-mecânicas dos poliuretanos obtidos e estas foram correlacionadas com os parâmetros estruturais. Os resultados foram justificados com base na intensidade das interações de hidrogênio, na mistura de fases, no volume dos extensores cíclicos e na presença de ligações cruzadas. Estes PUs estão sendo estudados com vistas à preparação de materiais biodegradáveis com propriedades mecânicas úteis.Segmented polyurethanes containing polycaprolactone as soft segment were prepared taking into account the biodegradable character of this compound. The hard block was produced by the reaction between tolylene diisocyanate and a chain extender (1,4 butanediol, sucrose or glucose. The mechanical and dynamical properties were evaluated as a function of the contents of rigid blocks. The results were analyzed on the basis of the intermolecular interactions, mainly H bonds, phase mixture, volume of cyclic chain extenders and crosslinking. These polyurethanes are being studied aiming at the preparation of biodegradable materials with useful mechanical properties.

  15. Relationship between structure and properties in high-temperature Bi(Al{sub 0.5}Fe{sub 0.5})O{sub 3}-PbTiO{sub 3} piezoelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yao Zhonghua, E-mail: yaozhhua@whut.edu.cn [Key Laboratory of Advanced Technology for Specially Functional Materials, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China); Peng Liyuan [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Liu Hanxing, E-mail: lhxhp@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Hao Hua; Cao Minghe; Yu Zhiyong [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2011-05-05

    Highlights: > Low-cost Bi-based high temperature piezoceramics. > A new high temperature system with Curie point >478 deg. C, compared to BiScO{sub 3}-PbTiO{sub 3} (450 deg. C). > Effectively improve the poling conditions. - Abstract: Ceramic samples of xBi(Al{sub 0.5}Fe{sub 0.5})O{sub 3}-(1 - x)PbTiO{sub 3} (BAF-PT, x = 0.05-0.5) solid solutions were fabricated using the conventional solid state reaction method. X-ray diffraction analysis revealed that all compositions can form single perovskite phase with tetragonal symmetry. The relationship between the tetragonal lattice parameters, tetragonality c/a, cell volume, and ferro-piezoelectric characterization as a function of x was systematically investigated. The BAF modification can effectively improve the poling condition at a proper BAF content. A combination of piezoelectric constant of d{sub 33} (50-60 pC/N), electromechanical planar coupling coefficients of k{sub p} (20.3-22.5%), and high Curie temperature T{sub c} (>478 deg. C) suggested that BAF-PT could be a good candidate for high-temperature piezoelectric applications.

  16. A Multiple-plane Approach to Measure the Structural Properties of Functionally Active Regions in the Human Cortex

    OpenAIRE

    Wang, Xin; Garfinkel, Sarah N.; King, Anthony P.; Angstadt, Mike; Dennis, Michael J.; Xie, Hong; Welsh, Robert C.; Tamburrino, Marijo B.; Liberzon, Israel

    2009-01-01

    Advanced magnetic resonance imaging (MRI) techniques provide the means of studying both the structural and the functional properties of various brain regions, allowing us to address the relationship between the structural changes in human brain regions and the activity of these regions. However, analytical approaches combining functional (fMRI) and structural (sMRI) information are still far from optimal. In order to improve the accuracy of measurement of structural properties in active regio...

  17. Relationships between conversion, temperature and optical properties during composite photopolymerization.

    Science.gov (United States)

    Howard, Benjamin; Wilson, Nicholas D; Newman, Sheldon M; Pfeifer, Carmem S; Stansbury, Jeffrey W

    2010-06-01

    Optical properties of composite restoratives, both cured and uncured, are of obvious importance in a procedure reliant on photoactivation, since they may affect light transmission and therefore materials conversion upon which mechanical properties and ultimate clinical performance are dependent. The objective of the present study was to evaluate simultaneous, real-time conversion, and the development of the temperature and optical properties. The dimethacrylate resin (Bis-GMA/TEGDMA 70/30mass%) was prepared at three filler loading (0, 35 or 70mass%: no fill, low and high fill, respectively) combined with three initiator concentrations (CQ/EDMAB: 0/0, 0.2/0.8 or 1.0/1.6mass%). Specimens were exposed to either low (50mWcm(-2)) or high (500mWcm(-2)) irradiance. Simultaneous conversion (near-IR peak area), temperature (thermocouple) and visible light transmission (UV-vis spectroscopy) measurements were conducted throughout the polymerization process. The refractive index of the resin rises linearly with conversion (r(2)=0.976), producing a refractive index match between resin/filler at approximately 58% conversion in these materials. The percentage increase in light transmission during conversion was greater for increasing filler levels. Higher CQ content led to maximum light transmission at slightly higher levels of conversion (60-65% and 50-55% for the high and low filled materials, respectively). The broad distribution of filler concentrations allows for the clinically relevant generalization that highly filled composites not only jeopardize absolute light transmission, conversion and depth of cure, but also demonstrate the complex interrelationship that exists between materials, processing conditions and the optical properties of dental composites. PMID:19913646

  18. Microstructure-properties relationship in barium titanate ceramics

    International Nuclear Information System (INIS)

    In this research, the effects of two kinds of additives in Barium Titanate ceramics were studied, in order to related the microstructure to electrical properties of the system. In the first series, the effects of Cerium (as a dopant) and in the second series the effects of Cerium along with lead on the electrical properties (with emphasis on the PTCR behavior) were evaluated. The amount of Ce was changed,from 0.1% to 0.5% mole and the amount of Pb was 30% which was considered to be substituted to Ba sites. The first series were sintered from 1100 centigrade to 1350 centigrade and the second ones from 11 00 centigrade to 1300 centigrade. After polishing and coating, the electrical properties were measured and analyzed. The r-results showed that Ce doping lowers the resistance of the systems (in both cases, without and with Pb) up to 0.3% mole and increased after that. The addition of Pb had increased the Tc of the system. The optimal sintering temperatures were about 1350 centigrade and 1200 centigrade in the ,first and second series respectively. In the first series, the Tc was about 125 centigrade and in the second series 180-200 centigrade. X-ray diffractometer)? showed that in the first series, the dominant phase was pure Barium Titanate and in the second series Barium Lead Titanate

  19. Properties and structure of aromatic ester solvents.

    Science.gov (United States)

    Aparicio, Santiago; Alcalde, Rafael; Dávila, María J; García, Begoña; Leal, José M

    2007-05-01

    This paper reports on an experimental and theoretical study of the aromatic ester solvents family. Several compounds were selected to analyze the different factors that influence their liquid-state properties and structures. The pressure-volume-temperature behavior of these fluids was measured accurately over wide temperature and pressure ranges and correlated successfully with the empirical TRIDEN equation. From the measured data the relevant derived coefficients of isothermal compressibility, isobaric expansibility, and internal pressure were calculated. The statistical associating fluid theory (SAFT) and perturbed chain statistical associating fluid theory (PC-SAFT) molecularly based equations of state were used to predict the PVT behavior with model parameters obtained from the correlation of available saturation literature data; the results provided by PC-SAFT equations of state were clearly superior for all of the studied solvents. The fluid's molecular level structure was studied by quantum computations at the B3LYP/6-311++g** level and classical molecular dynamics simulations in the NPT ensemble with the OPLS-AA forcefield. Molecular parameters, such as torsional barriers or cluster energetics, were analyzed as a function of ester structures. The molecular dynamics study provides, on one hand, theoretical values of thermophysical properties, which are compared with the experimental ones, and, on the other hand, valuable molecular level structural information. On the basis of both macroscopic and microscopic studies complex fluid structures were inferred with important effects arising from the geometries of the studied molecules and from the existence of remarkable intermolecular forces of dominating dipolar nature. PMID:17411084

  20. Molecular and Electronic Structure of Cyclic Trinuclear Gold(I) Carbeniate Complexes: Insights for Structure/Luminescence/Conductivity Relationships

    Energy Technology Data Exchange (ETDEWEB)

    McDougaldJr, Roy N [University of North Texas; Chilukuri, Bhaskar [University of North Texas; Jia, Huiping [University of Texas at Dallas; Perez, Michael R [University of Texas at Dallas; Rabaa, Hassan [Ibn Tofail Univ, ESCTM, Morocco; Wang, Xiaoping [ORNL; Nesterov, Vladimir [University of North Texas; Cundari, Thomas R. [University of North Texas; Gnade, Bruce E [University of Texas at Dallas; Omary, Mohammad A [University of North Texas

    2014-01-01

    An experimental and computational study of correlations between solid-state structure and optical/electronic properties of cyclotrimeric gold(I) carbeniates, [Au-3(RN=COR')(3)] (R, R' = H, Me, Bu-n, or (c)Pe), is reported. Synthesis and structural and photophysical characterization of novel complexes [Au-3(MeN=(COBu)-Bu-n)(3)], [Au-3((BuN)-Bu-n=COMe)(3)], [Au-3((BuN)-Bu-n=(COBu)-Bu-n)(3)], and [Au-3((c)PeN=COMe)(3)] are presented. Changes in R and R' lead to distinctive variations in solid-state stacking, luminescence spectra, and conductive properties. Solid-state emission and excitation spectra for each complex display a remarkable dependence on the solid-state packing of the cyclotrimers. The electronic structure of [Au-3(RN=COR')(3)] was investigated via molecular and solid-state simulations. Calculations on [Au-3(HN=COH)(3)] models indicate that the infinitely extended chain of eclipsed structures with equidistant Au-Au intertrimer aurophilic bonding can have lower band gaps, smaller Stokes shifts, and reduced reorganization energies (lambda). The action of one cyclotrimer as a molecular nanowire is demonstrated via fabrication of an organic field effect transistor and shown to produce a p-type field effect. Hole transport for the same cyclotrimer-doped within a poly(9-vinylcarbazole) host-produced a colossal increase in current density from similar to 1 to similar to 1000 mA/cm(2). Computations and experiments thus delineate the complex relationships between solid-state morphologies, electronic structures, and optoelectronic properties of gold(I) carbeniates.

  1. Quantitative structure activity relationships of some pyridine derivatives as corrosion inhibitors of steel in acidic medium.

    Science.gov (United States)

    El Ashry, El Sayed H; El Nemr, Ahmed; Ragab, Safaa

    2012-03-01

    Quantum chemical calculations using the density functional theory (B3LYP/6-31G DFT) and semi-empirical AM1 methods were performed on ten pyridine derivatives used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies. Quantum chemical parameters such as total negative charge (TNC) on the molecule, energy of highest occupied molecular orbital (E (HOMO)), energy of lowest unoccupied molecular orbital (E (LUMO)) and dipole moment (?) as well as linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (?) were correlated to corrosion inhibition efficiency of ten pyridine derivatives. A possible correlation between corrosion inhibition efficiencies and structural properties was searched to reduce the number of compounds to be selected for testing from a library of compounds. It was found that theoretical data support the experimental results. The results were used to predict the corrosion inhibition of 24 related pyridine derivatives. PMID:21695505

  2. Mistura polipropileno/poliestireno: um exemplo da relação processamento-estrutura-propriedade no ensino de polímeros / Polypropylene/polystyrene blend: an example of the processing-structure-property relationship in the education of polymers

    Scientific Electronic Library Online (English)

    Ricardo V. B., Oliveira; Creusa I., Ferreira; Luciano J. F., Peixoto; Otávio, Bianchi; Patricia A., Silva; Renan, Demori; Rodrigo P., Silva; Vinicius B., Veronese.

    Full Text Available As misturas ou blendas poliméricas continuam, apesar de seu longo estudo, a ser foco de pesquisas em diferentes áreas. A mistura de polipropileno e poliestireno é uma das mais estudadas principalmente pelo baixo custo e relevância tecnológica destes materiais. Neste trabalho, os alunos da disciplina [...] Processamento de Polímeros I (PG24) no Programa de Pós-Graduação em Ciência dos Materiais (PGCIMAT-UFRGS), realizaram em aula todo o processamento dos polímeros (polipropileno e poliestireno) e a produção das misturas poliméricas. A seguir, cada aluno ficou responsável por realizar um tipo de caracterização, que incluía a preparação das amostras, a análise em si e a discussão dos resultados da referida análise. Subsequentemente, os resultados foram confrontados em aula, onde se buscou as correlações existentes. E por fim, todos os alunos fizeram a revisão deste artigo, incluindo sugestões e críticas. Como esperado, a mistura de polipropileno e poliestireno forma uma blenda imiscível. Além disso, o processamento afetou as características dos polímeros, induzindo redução de massa molar e, como reflexo, redução de suas propriedades físicas. Na mistura PP/PS a separação de fase produziu domínios de PS da ordem de micra, com fraca adesão à matriz, o que explica essa perda de propriedades mecânicas. Abstract in english Polymer blends remain an important research topic in different areas, in spite of innumerous studies over the years. In particular, mixtures of polypropylene and polystyrene are among the most studied, mainly owing to their low cost and technological relevance. In this work, the students enrolled in [...] the discipline Polymer Processing I (PG24) in the Materials Science Graduate Program (PGCIMAT-UFRGS) produced blends of polypropylene and polystyrene, where all polymer processing steps were performed during lab classes. Then, each student undertook a characterization procedure with a specific technique, which included samples preparation, the analysis itself and discussion of the results. Subsequently, the results were confronted in the classroom, where we sought the correlations. Finally, all students reviewed this article, including suggestions and criticisms. As expected, the mixture of polystyrene and polypropylene formed an immiscible blend. Furthermore, the processing affected the characteristics of the polymers, leading to a reduction in molecular weight, and as a result a drop in its physical properties. In the PP/PS mixtures, phase separation produced PS domains with micrometers in size, and low adhesion to the PP matrix, which explains the loss of mechanical properties.

  3. Structure–property relationship of co-precipitated Cu-rich, Al2O3- or MgAl2O4-stabilized oxygen carriers for chemical looping with oxygen uncoupling (CLOU)

    International Nuclear Information System (INIS)

    Highlights: • Development of a synthesis–performance relationship for co-precipitated materials. • CLOU reaction mechanism for Al2O3-stabilized oxygen carriers is proposed. • CuAl2O4 and CuAlO2 show, respectively, slow decomposition and oxidation kinetics. • MgAl2O4-stabilized CuO (80 wt.%) are identified as a suitable material for CLOU. - Abstract: Chemical looping with oxygen uncoupling (CLOU) is a novel combustion technology that utilizes the decomposition reaction of an oxygen storage material to combust solid (hydro-)carbonaceous fuels. CuO is an ideal candidate for CLOU owing to its high oxygen uncoupling capacity (?10 wt.%) and its ability to release oxygen at temperatures relevant for chemical looping combustion (CLC), i.e. 850–1000 °C. Here, we investigate the feasibility of Cu-rich, Al2O3 or MgAl2O4-stabilized oxygen carriers containing 70–90 wt.% CuO for the CLOU process. Al2O3- and MgAl2O4-stabilized oxygen carriers were synthesized using a co-precipitation technique and calcined either at 800 °C or 1000 °C. The CLOU performance of the oxygen carriers was evaluated at 950 °C in a fluidized bed reactor using a N2 atmosphere for the decomposition reaction and a mixture of 10.5 vol.% O2 and 89.5 vol.% N2 for the re-oxidation reaction. It was found that the calcination temperature and the surface area had no significant influence on the oxygen carrying capacity of the synthesized oxygen carriers. The oxygen uncoupling capacity of Al2O3-stabilized oxygen carriers was substantially below the theoretically expected values due to the formation of the mixed oxides CuAl2O4 and CuAlO2. Based on thermo-gravimetric measurements, a reaction pathway for the oxygen release and re-oxidation reactions of Al2O3-stabilized CuO was proposed. On the other hand, no interaction between MgAl2O4 and the active phase, i.e. CuO was observed. As a consequence, MgAl2O4-stabilized oxygen carriers possessed a high oxygen uncoupling capacity very close to the theoretical values. Owing to its stable and high oxygen release capacity, MgAl2O4-supported oxygen carriers containing 80 wt.% CuO were identified as a promising material for CLOU

  4. Preliminary analysis of the relationship between structure and anthelmintic activity of condensed tannins in cattle nematodes

    DEFF Research Database (Denmark)

    Desrues, Oliver; Enemark, Heidi L.

    2013-01-01

    Some plant secondary metabolites as tannins have direct anthelminthic properties and may play a role in the control of nematodes in livestock. However, their great diversity in structural characteristics and different levels of content in plants are responsible for a highly variable response in anthelmintic activity, as measured in vitro. The aim of the present study was to assess the relationship between tannin structure and anthelmintic activity using an in vitro assay. We used a series of purified tannins (from 65% to 100% of purity) characterized for their degree of polymerization (mDP), prodelphinidin/procyanidin (PC/PD) ratio and cis/trans ratio by thiolytic degradation. Tannins diluted in two concentrations in water, epigallocatechin gallate (EGCG), positive (ivermectin) and negative (water) controls were examined by the Larval Feeding Inhibition Assay (LFIA) with first stage larvae (L1) of the cattle nematode Cooperia oncophora in triplicates. All extracted condensed tannins, in particular sainfoin, white clover and pine tree inhibited the feeding of L1 at the high concentration. There was a trend towards lower inhibition with decreasing PD/PC ratio. However, despite black currant’s 95 % of PD, it showed a low inhibition which could be related to a very low cis/trans ratio. Based on these preliminary findings it is difficult to define a relationship between the structural parameters and anthelmintic activity.

  5. Preliminary analysis of the relationship between structure and anthelmintic activity of condensed tannins in cattle nemaotdes

    DEFF Research Database (Denmark)

    Desrues, Olivier; Larsen Enemark, Heidi

    Some plant secondary metabolites as tannins have direct anthelminthic properties and may play a role in the control of nematodes in livestock. However, their great diversity in structural characteristics and different levels of content in plants are responsible for a highly variable response in anthelmintic activity, as measured in vitro. The aim of the present study was to assess the relationship between structure and anthelmintic activity using an in vitro assay. We used a series of purified tannins (from 65% to 100% of purity) characterized for their degree of polymerization (mDP), prodelphinidin/procyanidin ratio and cis/trans ratio by thiolytic degradation. Tannins diluted in two concentrations in water, epigallocatechin gallate, positive (ivermectin) and negative (water) controls were examined by the Larval Feeding Inhibition Assay (LFIA) with first stage larvae (L1) of the cattle nematode Cooperia oncophora in triplicates. All extracted condensed tannins, in particular sainfoin, white clover and pine tree inhibited the feeding of L1 at the high concentration. There was a trend towards lower inhibition with decreasing PD/PC ratio. However, despite black currant had 95 % of PD, it showed a low inhibition which could be related to a very low cis/trans ratio. Based on these preliminary findings it is difficult to define a relationship between the structural parameters and anthelmintic activity.

  6. Morphology-mechanical Property Relationship of Polypropylene/starch Blends

    OpenAIRE

    C. H. Azhari; S. F. Wong

    2001-01-01

    The influence of morphology on mechanical property of several polypropylene/starch (PP/starch) blends of varying compositions was studied. The blends prepared were at wt%PP/wt%starch of 97.5/2.5, 95/5, 92.5/7.7, 90/10, 87.5/12.5 and 85/15. The morphology of the blends observed, using scanning electron microscopy showed them to be immiscible blends with distinct polymer-starch domains at high starch volume fractions (85%PP/15%starch-87.5%PP/12.5%starch), which gradually showed the morphology o...

  7. Structure-Odor Relationships for Pyrazines with Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Ovidiu Ivanciuc

    2002-05-01

    Full Text Available The flavor class prediction of chemical compounds can be efficiently performed with structure-odor relationships (SOR, leading to a better understanding of the mechanism of odor perception. SOR models for various odor classes were developed with a wide variety of structural descriptors and statistical equations. We have investigated the application of support vector machines (SVM for the classification of 98 tetra-substituted pyrazines representing three odor classes, namely 32 green, 23 nutty, and 43 bell-pepper. The chemical structure of the pyrazines was encoded by five theoretical descriptors, namely the sum of electrotopological indices, the number of carbon atoms of the substituent R2, the charge on the first atom of the substituent R4 computed with an ab initio method (Hartee-Fock with a 3-21G basis set, and the molecular surface of the substituents R1 and R3. Three sets of SVM experiments were performed for the classification of pyrazines, each one considering the classification of one class of compounds against the compounds from the remaining two classes. The SVM models were computed with the dot, polynomial, radial basis function, neural, and anova kernels. The leave-10%-out cross-validation results represent the main criterion for selecting the best SVM model that has the highest prediction power. The results obtained demonstrate that the SVM classification of pyrazines in aroma classes depends strongly on the kernel type and various parameters that control the kernel shape. In general, the neural kernel gives the worst results. The best predictions were obtained with the polynomial kernel of degree 2 for the green and bell-pepper classes, and with the anova kernel (? = 0.5 and d = 1 for the nutty pyrazines. The classification of chemical compounds in odor classes with SOR models can be efficiently made with support vector machines. The solution of the SVM model is a unique hyperplane that guarantees a maximum separation between two classes of chemical compounds. This hyperplane can be computed very fast and represents the solution of a quadratic programming problem, but the classification results depend on the kernel type and structural descriptors. The identification of the optimum predictive kernel and elimination of the overfitted SVM models requires extensive cross-validation experiments.

  8. The Humor Styles Questionnaire in Italy: Psychometric Properties and Relationships With Psychological Well-Being

    Directory of Open Access Journals (Sweden)

    Saulo Sirigatti

    2014-08-01

    Full Text Available This study investigated the psychometric properties of the Humor Styles Questionnaire (HSQ and the relation between humor and psychological well-being within the context of Italy. A total of 293 (178 females, 115 males Italian high school and undergraduate university students – whose ages ranged from 14 to 25 years – completed the Italian versions of the HSQ and the Ryff’s Psychological Well-Being scales (RPWB. The HSQ scale reliabilities were generally acceptable, and intercorrelations among the scales were rather low; the confirmatory factor analysis supported the four-factor structure. Males reported significantly more use of Aggressive humor than did females; no differences were found between adolescents and young adults in the use of humor styles. Affiliative and Self-enhancing humor styles were positively associated with the six dimensions of the RPWB, whereas Self-defeating humor was negatively correlated with the RPWB scales. SEM analysis showed a significant and positive relationship between humor as measured by the HSQ and psychological well-being as assessed by the RPWB. Overall, the findings supported the theoretical structure and usefulness of the HSQ in an Italian context and the differential role of humor components in the various dimensions of psychological well-being.

  9. Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites

    OpenAIRE

    Monsiva?is-barro?n, Alejandra J.; Jaime Bonilla-Rios; Antonio Sánchez-Fernández

    2014-01-01

    Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified hal...

  10. Relationships between the reinforcement properties and the crystallization of MMc

    OpenAIRE

    Jackowski, J.; Suchora, M.; Szweycer, M.

    2008-01-01

    Occurrence of a reinforcing phase in a cooling composite casting causes that its crystallization goes differently as compared to the casting without reinforcing (of traditional design). This affects the forming process of the composite structure since the moment of mixing of the components until total solidification of the composite matrix. The present paper aims at presenting several problems related to crystallization of composite castings (particle reinforced and with saturated reinforceme...

  11. Relationships among the physical properties of biodiesel and engine fuel system design requirement

    Directory of Open Access Journals (Sweden)

    G.Lakshmi Narayana Rao, A.S. Ramadhas, N. Nallusamy, P.Sakthivel

    2010-09-01

    Full Text Available Biodiesel, an alternative fuel can be used in diesel engines as neat or blended with diesel. The physio-chemical properties of fuel are important in design of fuel system for compression ignition engines run on diesel, biodiesel or biodiesel blends. Biodiesel (B100 standards specify the limit values of these properties for blending with diesel. However, there are variations in the properties of biodiesel. The properties of biodiesel vary depending on the feedstock, vegetable oil processing, production methods and degree of purification. The objective of this study is to estimate the mathematical relationships between viscosity, density, heating values and flash point among various biodiesel samples. There is a high regression between various properties of biodiesel and the relationships between them are observed to be considerably regular.

  12. Structure activity relationships to assess new chemicals under TSCA

    Energy Technology Data Exchange (ETDEWEB)

    Auletta, A.E. [Environmental Protection Agency, Washington, DC (United States)

    1990-12-31

    Under Section 5 of the Toxic Substances Control Act (TSCA), manufacturers must notify the US Environmental Protection Agency (EPA) 90 days before manufacturing, processing, or importing a new chemical substance. This is referred to as a premanufacture notice (PMN). The PMN must contain certain information including chemical identity, production volume, proposed uses, estimates of exposure and release, and any health or environmental test data that are available to the submitter. Because there is no explicit statutory authority that requires testing of new chemicals prior to their entry into the market, most PMNs are submitted with little or no data. As a result, EPA has developed special techniques for hazard assessment of PMN chemicals. These include (1) evaluation of available data on the chemical itself, (2) evaluation of data on analogues of the PMN, or evaluation of data on metabolites or analogues of metabolites of the PMN, (3) use of quantitative structure activity relationships (QSARs), and (4) knowledge and judgement of scientific assessors in the interpretation and integration of the information developed in the course of the assessment. This approach to evaluating potential hazards of new chemicals is used to identify those that are most in need of addition review of further testing. It should not be viewed as a replacement for testing. 4 tabs.

  13. Crystal Structure-Ionic Conductivity Relationships in Doped Ceria Systems

    DEFF Research Database (Denmark)

    Omar, Shobit; Wachsman, Eric D.

    2009-01-01

    In the past, it has been suggested that the maximum ionic conductivity is achieved in ceria, when doped with an acceptor cation that causes minimum distortion in the cubic fluorite crystal lattice. In the present work, this hypothesis is tested by measuring both the ionic conductivity and elastic lattice strain of 10 mol% trivalent cation-doped ceria systems at the same temperatures. A consistent set of ionic conductivity data is developed, where the samples are synthesized under similar experimental conditions. On comparing the grain ionic conductivity, Nd0.10Ce0.90O2?? exhibits the highest ionic conductivity among other doped ceria systems. The grain ionic conductivity is around 17% higher than that of Gd0.10Ce0.90O2?? at 500°C, in air. X-ray diffraction profiles are collected on the sintered powder of all the compositions, from room temperature to 600°C, in air. From the lattice expansion data at high temperatures, the minimal elastic strain due to the presence of dopant is observed in Dy0.10Ce0.90O2??. Nd0.10Ce0.90O2?? exhibits larger elastic lattice strain than Dy0.10Ce0.90O2?? with better ionic conductivity at intermediate temperatures. Therefore, it is shown that the previously proposed crystal structure–ionic conductivity relationship based on minimum elastic strain is not sufficient to explain the ionic conductivity behavior in ceria-based system.

  14. Structure-toxicity relationships for alkanones and alkenones.

    Science.gov (United States)

    Schultz, T W; Sinks, G D; Hunter, R S

    1995-01-01

    The relative toxicity (log IGC-1(50)) of 54 selected alkanones, both aliphatic and aromatic, as well as, alkenones and alkynones was evaluated in the static Tetrahymena pyriformis population growth assay. Excess toxicity, an indicator of bioreactivity, was associated only with the alpha-beta unsaturated alkenones and alkynones. Moreover, the alkynones were found to be more toxic than corresponding alkenones. A high quality 1-octanol/water partition coefficient (log Kow) dependent structure-toxicity relationship, log IGC-1(50) = 0.86 (log Kow) - 2.27; r2 = 0.955, was developed for alkanones. This QSAR represented the nonpolar narcosis mechanism of toxic action. Toxicity of alkenones was predicted by the highest-occupied-molecular-orbital energy (HOMO), log IGC-1(50) = -3.474 (HOMO) -35.357; r2 = 0.897, and the difference between HOMO and the lowest-unoccupied-molecular-orbital energy (LUMO), log IGC-1(50) = -3.559 (HOMO-LUMO gap) - 36.106; r2 = 0.903. The alpha-beta unsaturated ketones are considered soft electrophiles. Moreover, the toxicity of the aliphatic alkanones and alkenones was predicted by log Kow and LUMO, log IGC-1(50) = 0.69 (log Kow) - 2.55 (LUMO) + 0.05; r2 = 0.852. PMID:7497340

  15. Thermal and structural properties of ionic fluids

    CERN Document Server

    Bartsch, Hendrik; Bier, Markus

    2015-01-01

    The electrostatic interaction in ionic fluids is well-known to give rise to a characteristic phase behavior and structure. Sometimes its long range is proposed to single out the electrostatic potential over other interactions with shorter ranges. Here the importance of the range for the phase behavior and the structure of ionic fluids is investigated by means of grandcanonical Monte Carlo simulations of the lattice restricted primitive model (LRPM). The long-ranged electrostatic interaction is compared to various types of short-ranged potentials obtained by sharp and/or smooth cut-off schemes. Sharply cut off electrostatic potentials are found to lead to a strong dependence of the phase behavior and the structure on the cut-off radius. However, when combined with a suitable additional smooth cut-off, the short-ranged LRPM is found to exhibit quantitatively the same phase behavior and structure as the conventional long-ranged LRPM. Moreover, the Stillinger-Lovett perfect screening property, which is well-known...

  16. Structure-dielectric properties relationship in Mg-Mn co-doped Ba0.4Sr0.6TiO3/MgAl2O4 tunable microwave composite ceramics

    International Nuclear Information System (INIS)

    xMgO-yMnCO3-0.70(1 - x - y)Ba0.4Sr0.6TiO3-0.30(1 - x - y)MgAl2O4 (where x, y = 0.0 wt% and x = 1.0 wt%, y = 0.5, 1.0, 2.0, 5.0, 10.0 wt%) composite ceramics synthesized by the solid-state reaction show two crystalline phases, corresponding to the Ba0.4Sr0.6TiO3 and MgAl2O4 phases. At a low MnCO3 content (y ? 2.0 wt%), weak diffuseness is visible, while strong diffuseness is observed for a higher MnCO3 content. For x = 0.01 and 0.01 ? y ? 0.02, high tunability is attributed to the small cooperative displacements of Ti4+ ions in the close packed oxygen octahedra of the BST system. The Q value gradually increases with y, potentially due to the microstructural evolution of the BST lattice structure characterized by Raman spectra. Interestingly, the high Q value of the composition with x = 0.01 and y ? 0.05 is in a wide frequency range, which may play an important role in the engineering of the electric-field tunable microwave elements.

  17. The Influence of Personal Characteristics and Relationship Properties on Marital Support

    OpenAIRE

    Verhofstadt, Lesley L.; Ann Buysse; Inge Devoldre; Kim De Corte

    2007-01-01

    Self-report data from 200 married couples were used to examine personal characteristics (i.e., extraversion, neuroticism, attachment-related anxiety and avoidance) and relationship properties (i.e., intimacy, commitment, marital conflict, and marital satisfaction) as determinants of supportive behaviours and perceptions of support availability within marital relationships. The data revealed that both personal and relational variables had important value in the prediction of support perception...

  18. Structure-activity relationship of immunostimulatory effects of phthalates

    Directory of Open Access Journals (Sweden)

    Nielsen Gunnar D

    2008-10-01

    Full Text Available Abstract Background Some chemicals, including some phthalate plasticizers, have been shown to have an adjuvant effect in mice. However, an adjuvant effect, defined as an inherent ability to stimulate the humoral immune response, was only observed after exposure to a limited number of the phthalates. An adjuvant effect may be due to the structure or physicochemical characteristics of the molecule. The scope of this study was to investigate which molecular characteristics that determine the observed adjuvant effect of the most widely used phthalate plasticizer, the di-(2-ethylhexyl phthalate (DEHP, which is documented as having a strong adjuvant effect. To do so, a series of nine lipophilic compounds with structural and physicochemical relations to DEHP were investigated. Results Adjuvant effect of phthalates and related compounds were restricted to the IgG1 antibody formation. No effect was seen on IgE. It appears that lipophilicity plays a crucial role, but lipophilicity does not per se cause an adjuvant effect. In addition to lipophilicity, a phthalate must also possess specific stereochemical characteristics in order for it to have adjuvant effect. Conclusion The adjuvant effect of phthalates are highly influenced by both stereochemical and physico-chemical properties. This knowledge may be used in the rational development of plasticizers without adjuvant effect as well as in the design of new immunological adjuvants.

  19. Relationship between chemical transformations and optical properties of aerosols

    Science.gov (United States)

    Lu, J.; Rudich, Y.; Flores, M.

    2010-12-01

    The optical properties of complex aerosols, important in determining their radiative forcing in the atmosphere and, subsequently, their impact on climate, are extensively examined. There is an abundance of natural and anthropogenic organic compounds in the atmosphere that can be released as primary aerosols or form secondary organic aerosols (SOAs) via photocchemical reactions with OH, NO3, and O3. SOAs can undergo further processing in the atmosphere with oxidative species, changing the chemical, physical, and optical properties of the particles. Absorbing aerosol components include nitrated aromatics, aromatic polycarboxylic acids, phenols, polycyclic aromatic hydrocarbons, and nitrated inorganics. Many of these species have been found in atmospheric particles. Some of them are strong absorbers at long UV wavelengths. Such aerosols may affect downward UV irradiances in urban location and may be important for predicting smog evolution in urban areas. It is possible that such species can form by reactions of NOx with organic aerosols. Using cavity ring down spectrometry and aerosol mass spectrometry we show for the first time that after exposure to NOx, aerosols coated by PAHs undergo a large change in the extinction efficiency as a result of a chemical reaction. The main product peak is mononitrated-BaP (m/z 267 and m/z 297). Its product formation is accompanied by a subsequent decrease in reactant peak (m/z 252), which appears to be mirrored by the increase in Qext with time. This study supports Mark Jacobson’s suggestion that aerosol aging downwind from urban location due to the coupling with NOx chemistry may lead to increased light extinction due to more absorption at longer wavelengths. This process may have implications for regional processes.

  20. Improved relationships for the thermodynamic properties of carbon phases at detonation conditions

    Science.gov (United States)

    Stiel, L. I.; Baker, E. L.; Murphy, D. J.

    2014-05-01

    Accurate volumetric and heat capacity relationships have been developed for graphite and diamond carbon forms for use with the Jaguar thermochemical equilibrium program for the calculation of the detonation properties of explosives. Available experimental thermodynamic properties and Hugoniot values have been analyzed to establish the equations of state for the carbon phases. The diamond-graphite transition curve results from the equality of the chemical potentials of the phases. The resulting relationships are utilized to examine the actual phase behaviour of carbon under shock conditions. The existence of metastable carbon states is established by analyses of Hugoniot data for hydrocarbons and explosives at elevated temperatures and pressures. The accuracy of the resulting relationships is demonstrated by comparisons for several properties, including the Hugoniot behaviour of oxygen-deficient explosives at overdriven conditions.

  1. Structure and Properties of LENRA/ Silica Composite

    International Nuclear Information System (INIS)

    The sol-gel reaction using tetra ethoxysilane (TEOS) was conducted for modified natural rubber (NR) matrix to obtain in situ generated NR/ silica composite. The present of acrylate group in the modified NR chain turns the composite into radiation-curable. The maximum amount of silica generated in the matrix was 50 p hr by weight. During the sol-gel process the inorganic mineral was deposited in the rubber matrix forming hydrogen bonding between organic and inorganic phases. The composites obtained were characterized by various techniques including thermogravimetric analysis and infrared spectrometry to study their molecular structure. The increase in mechanical properties was observed for low silica contents (30 p hr) where more silica were generated, agglomerations were observed at the expense of the mechanical properties. From the DMTA data, it shows an increase of the interaction between the rubber and silica phases up to 30 p hr TEOS. Structure and morphology of the heterogeneous system were analyzed by transmission electron microscopy. The average particle sizes of between 150 nm to 300 nm were achieved for the composites that contain less than 20 p hr of TEOS. (author)

  2. Anharmonic properties of rocksalt structure solids

    International Nuclear Information System (INIS)

    An effort has been made for obtaining the anharmonic properties of rocksalt structure solids starting from primary physical parameters viz. nearest-neighbor distance and hardness parameter assuming long- and short-range potentials at elevated temperatures. The elastic energy density for a deformed crystal can be expanded as power series of strains for obtaining coefficients of quadratic, cubic and quartic terms which are known as the second-, third- and fourth-order elastic constants, respectively. When the values of the higher-order elastic constants are known for a crystal, many of the anharmonic properties of the crystal can be treated within the limit of the continuum approximation in a quantitative manner. In this study, higher-order elastic constants are computed up to their melting temperature for rocksalt structure solids, which are alkali cyanides, sodium and potassium halides. The first order pressure derivatives of second- and third-order elastic constants, the second-order pressure derivatives of second-order elastic constants and partial contractions are also evaluated at different temperatures for these substances. The results thus obtained are compared with experimental data and found in well agreement with present values

  3. The influence of binarization threshold in soil percolation: relationships between soil physical properties

    Science.gov (United States)

    Capa Morocho, M. I.; Ruiz-Ramos, M.; Tarquis, A. M.

    2011-12-01

    This study examines the influence of the binarization threshold used to interpret 3D grey images acquired by X-ray computed tomography of a soil at different bulk densities. One objective was to generate criteria for choosing the optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation. The study also attempts to identify relationships between soil physical properties, density, porosity and connectivity. The starting point was the outputs of the simulation of 40000 particles following a directed random walk algorithms in soils with densities from 1.2 to1.6 (Mg/m3) and up to 7 thresholds for each image. These data consisted of 31 files containing the simulated end points of the 40000 random walks. MATLAB software was used for computing the frequency matrix of the number of particles arriving at every end point of the random walks and their 3D representation. The relationships identified were: the higher the bulk density the lower the porosity and the fewer the final positions of the 40000 particles; each soil sample shows different sensibility to the threshold; a higher threshold always reflects a higher porosity, greater connectivity and greater number of final positions at greater depth, regardless of density (Fig.1). Soil structure and connectivity between pores determines the 3D distribution of final positions with at least one fluid particle; and the higher the threshold, the lower the influence of the structure. A criterion to select the threshold was identified: final positions were divided in two subgroups, cg1 (positions with frequency of the number of particles received greater than the median) and cg2 (frequency lower or equal to median). Images with maximum difference between the Z coordinate of the center of gravity of both subgroups were selected as those with optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation, allowing us for comparing the percolation of soils with different bulk density. Acknoledgements This work has been funded by projects AGL2010-21501/AGR (MICINN) and PEII10-0248-5680 (JJCLM)

  4. Mapping the structure, composition and mechanical properties of human teeth

    International Nuclear Information System (INIS)

    The structure-property relationship in human adult and baby teeth was characterised by grazing-incidence synchrotron radiation diffraction, optical and atomic-force microscopy, in addition to Vickers indentation. Similarities and differences between both types of teeth have been highlighted and discussed. Depth-profiling results indicated the existence of contrasting but distinct gradual changes in crystal disorder, phase abundance, crystallite size and hardness within the baby and adult enamel, thus confirming the graded nature of human teeth. When compared to the adult tooth, the baby enamel is softer, more prone to fracture, but has larger hydroxyapatite grains. Vickers hardness of the enamel was load-dependent but load-independent in the dentine. The use of a 'bonded-interface' technique revealed the nature and evolution of deformation-microfracture damage around and beneath Vickers contacts

  5. Lease maturity and initial rent: is there a term structure for UK commercial property leases?

    OpenAIRE

    Bond, S. A.; Loizou, P.; McAllister, Patrick

    2005-01-01

    This paper investigates the relationship between lease maturity and rent in commercial property. Over the last decade market-led changes to lease structures, the threat of government intervention and the associated emergence of the Codes of Practice for commercial leases have stimulated growing interest in pricing of commercial property leases. Seminal work by Grenadier (1995) derived a set of hypotheses about the pricing of different lease lengths in different market conditions. Whilst there...

  6. A NON-LINEAR STRUCTURE-PROPERTY MODEL FOR OCTANOL-WATER PARTITION COEFFICIENT

    OpenAIRE

    Yerramsetty, Krishna M.; Neely, Brian J.; Gasem, Khaled A. M.

    2012-01-01

    Octanol-water partition coefficient (Kow) is an important thermodynamic property used to characterize the partitioning of solutes between an aqueous and organic phase and has importance in such areas as pharmacology, pharmacokinetics, pharmacodynamics, chemical production and environmental toxicology. We present a non-linear quantitative structure-property relationship model for determining Kow values of new molecules in silico. A total of 823 descriptors were generated for 11,308 molecules w...

  7. Molecular design chemical structure generation from the properties of pure organic compounds

    CERN Document Server

    Horvath, AL

    1992-01-01

    This book is a systematic presentation of the methods that have been developed for the interpretation of molecular modeling to the design of new chemicals. The main feature of the compilation is the co-ordination of the various scientific disciplines required for the generation of new compounds. The five chapters deal with such areas as structure and properties of organic compounds, relationships between structure and properties, and models for structure generation. The subject is covered in sufficient depth to provide readers with the necessary background to understand the modeling

  8. Anti-inflammatory effects of a triple-bond resveratrol analog: structure and function relationship.

    Science.gov (United States)

    Antus, Csenge; Radnai, Balazs; Dombovari, Peter; Fonai, Fruzsina; Avar, Peter; Matyus, Peter; Racz, Boglarka; Sumegi, Balazs; Veres, Balazs

    2015-02-01

    Resveratrol is a polyphenol found in grapes and red wine, showing well-characterized anti-inflammatory and antiproliferative activities. In order to exceed resveratrol?s biological effects and to reveal the structural determinants of the molecule?s activity, numerous derivatives were synthesized recently. Most of these resveratrol analogs vary from the original molecule in the number, position or identity of the phenolic functional groups. Investigation of the analogs provided important data regarding structure-activity relationship of the molecule. With the exception of cis- and trans-resveratrol and the reduced form dihydroresveratrol, little is known about the molecular effects of the stilbene backbone. In the present study we investigated the anti-inflammatory properties of a new, triple-bond resveratrol analog, 3,4',5-trihydroxy-diphenylacetylene (TDPA) on lipopolysaccharide-stimulated RAW macrophages. We found that the analog had weaker antioxidant activity and stronger inhibitory effect on nuclear factor-kappaB activation, and on cyclooxygenase-2, tumor necrosis factor ? and interleukin-6 production. It also prevented lipopolysaccharide-induced depolarization of the mitochondrial membrane. In contrast to resveratrol, TDPA increased the phosphorylation of c-Jun N-terminal and p38 mitogen activated protein kinases. In summary, we identified a novel compound with better anti-inflammatory properties than resveratrol. Our results contributed to a better understanding of the structural determinants of resveratrol?s biological activities. PMID:25528327

  9. Relationships between aging of PAHs and soil properties

    International Nuclear Information System (INIS)

    Sequestration and diffusion of three polycyclic aromatic hydrocarbons (PAHs) in seven Chinese soils were investigated for up to 200 days in sterile soil microcosms as functions of soil property and aging time. The aging of the PAHs, assessed using a mild extractant that removes primarily the labile fraction, showed a biphasic behavior. The rapid diffusion from labile to nonlabile domains was mainly dependent upon the distribution of meso- and micropore fraction and total organic carbon content. Meanwhile, the slow diffusion was found to decrease with the increase of the content of soil organic carbon, particularly of hard organic carbon (p < 0.01) and the meso- and micropore fraction, as well as with the increasing molecular size of PAHs. This work offers evidence that analyses of organic carbon fractionation and porosity are important to adequately assess the mechanistic basis of sequestration and diffusion of organic contaminants in soils. - Highlights: ? PAH aging exhibits a biphasic behavior in the soils. ? The rapid diffusion depends on meso- and micropore distribution and TOC content. ? The slow diffusion is controlled by hard organic carbon and pore distribution. ? Hard organic carbon can act as a better predictor of PAH sequestration than TOC. - Hard organic carbon and meso- and micropore distribution can act as better predictors of PAH sequestration in soils than total organic carbon and surface area, respectively.

  10. Relationships between the reinforcement properties and the crystallization of MMc

    Directory of Open Access Journals (Sweden)

    J. Jackowski

    2008-04-01

    Full Text Available Occurrence of a reinforcing phase in a cooling composite casting causes that its crystallization goes differently as compared to the casting without reinforcing (of traditional design. This affects the forming process of the composite structure since the moment of mixing of the components until total solidification of the composite matrix. The present paper aims at presenting several problems related to crystallization of composite castings (particle reinforced and with saturated reinforcement that have been the subjects of the research work performed by the team of the Foundry Section of the Pozna? University of Technology. The review displays the spheres of the technology of composite casting materials that are well known and the ones that require more detailed research.

  11. A data mining approach to finding relationships between reservoir properties and oil production for CHOPS

    Science.gov (United States)

    Cai, Yongxiang; Wang, Xin; Hu, Kezhen; Dong, Mingzhe

    2014-12-01

    Cold heavy oil production with sand (CHOPS) is a primary oil extraction process for heavy crude oil and reservoir properties are key factors that contribute to the effectiveness of CHOPS. However, identification of the key reservoir properties and quantification of the relationships between the reservoir properties and the oil production are still challenging tasks. In this paper, we propose the use of a data mining approach for finding quantitative relationships between various reservoir properties and oil production for CHOPS. The approach includes four steps: firstly, a set of reservoir properties are identified to describe reservoir characteristics through a petrophysical analysis. In addition to common parameters, such as porosity and permeability, two new parameters - a fluid mobility factor and the maximum inscribed rectangular of net pay (MIRNP) - are proposed. Secondly, three new parameters to describe the production performance of wells are proposed: the peak value, effective life cycle and effective yield. Next, the fuzzy ranking method is used to rank the importance of the identified reservoir properties in terms of oil production. Finally, association rule mining is used to obtain quantitative relationships between reservoir property variables and the production performance of wells. The proposed methods have been applied for 118 wells in the Sparky Formation of the Lloydminster heavy oil field in Alberta. The result shows that the production performance of wells in the area could be described and predicted by using the found quantitative relations.

  12. The relationship between structural and functional connectivity: graph theoretical analysis of an EEG neural mass model.

    Science.gov (United States)

    Ponten, S C; Daffertshofer, A; Hillebrand, A; Stam, C J

    2010-09-01

    We investigated the relationship between structural network properties and both synchronization strength and functional characteristics in a combined neural mass and graph theoretical model of the electroencephalogram (EEG). Thirty-two neural mass models (NMMs), each representing the lump activity of reasonably large groups of interacting excitatory and inhibitory neurons, were reciprocally and excitatory coupled using random rewiring as described by Watts and Strogatz. Numerical analysis of the network revealed an abrupt transition towards a synchronized state as a function of increasing coupling strength alpha. Synchronization increased with increasing degree and decreasing regularity of the network. Parameters of the functional network showed a diverse dependency on structural connectivity: normalized clustering coefficient gamma and path length lambda increased with increasing alpha. For sufficiently large alpha, however, gamma decreased with increasing rewiring probability p, while lambda increased. Hence, a structured functional network exists despite the randomness of the underlying structural network. That is, patterns of functional connectivity are influenced by patterns of the corresponding structural level but do not necessarily agree with those. PMID:19853665

  13. The Relationship among Ownership Structure, Managers’ Factors and Firm Technical Innovation: a Case Study

    OpenAIRE

    Xia, Dong

    2005-01-01

    The empirical research on the relationship between firm ownership structure and technical innovation, is the weak tache in existing research. Based on existing research result, this article empirically studies the impact of managers on relationship between ownership structure and technical innovation by analyzing large sample database. And it proves that firm manager is the important link between firm ownership structure and technical innovation.
    Key words: ownership structure, at...

  14. Composition, structure, and luminescent properties of SiOxNy(Si) composite layers containing Si nanocrystals

    OpenAIRE

    Baru, V. G.; Dyuzhikov, I. N.; Pokalyakin, V. I.; Shevchenko, O. F.; Skryleva, E. A.; Zhigalina, O. M.

    2005-01-01

    A relationship between the chemical composition, structure and luminescent properties of light-emitting SiOxNy(Si) composite layers with Si nanocrystals is demonstrated. Photoluminescence (PL) with a maximum of intensity at 500-600 nm is observed in a narrow region of chemical compositions with relatively small Si excess (about 10 at. %). Composite layers structure is studied by means of HRTEM. Appearance of nanocrystals due to annealing is accompanied by substantial growth ...

  15. Structural properties of reflected Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars NØrvang; Mandjes, Michel

    2008-01-01

    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 ?(t) := EVt and ?(t) := VarVt. We prove that for the one- and two-sided reflection we have ?(t) is increasing and concave, whereas for the one-sided reflection we also show that ?(t) is increasing. In most proofs we first establish the claim for the discrete-time counterpart (that is, a reflected random walk), and then we use a limiting argument. A key step in our proofs for the two-sided reflection is a new representation of the position of the reflected process in terms of the driving Lévy process.

  16. Structural Properties of Realistic Cultural Space Distributions

    CERN Document Server

    Babeanu, Alexandru-Ionut; Garlaschelli, Diego

    2015-01-01

    An interesting sociophysical research problem consists of the compatibility between collective social behavior in the short term and cultural diversity in the long term. Recently, it has been shown that, when studying a model of short term collective behavior in parallel with one of long term cultural diversity, one is lead to the puzzling conclusion that the 2 aspects are mutually exclusive. However, the compatibility is restored when switching from the randomly generated cultural space distribution to an empirical one for specifying the initial conditions in those models. This calls for understanding the extent to which such a compatibility restoration is independent of the empirical data set, as well as the relevant structural properties of such data. Firstly, this work shows that the restoration patterns are largely robust across data sets. Secondly, it provides a possible mechanism explaining the restoration, for the special case when the cultural space is formulated only in terms of nominal variables. T...

  17. On Structure and Properties of Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Zbigniew H. Stachurski

    2011-09-01

    Full Text Available Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy materials: (i metallic; (ii thin films; (iii organic and inorganic thermoplastics; and (iv amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ideas of Bernal on the structure of liquids were followed by experiments and computer models for the packing of spheres. Modern approach is to carry out computer simulations with prediction that can be tested by experiments. A geometrical concept of an ideal amorphous solid is presented as a novel contribution to the understanding of atomic arrangements in amorphous solids.

  18. Quantitative structure carcinogenicity relationship for detecting structural alerts in nitroso-compounds

    International Nuclear Information System (INIS)

    In this work, Quantitative Structure-Activity Relationship (QSAR) modelling was used as a tool for predicting the carcinogenic potency of a set of 39 nitroso-compounds, which have been bioassayed in male rats by using the oral route of administration. The optimum QSAR model provided evidence of good fit and performance of predicitivity from training set. It was able to account for about 84% of the variance in the experimental activity and exhibited high values of the determination coefficients of cross validations, leave one out and bootstrapping (q2LOO = 78.53 and q2Boot = 74.97). Such a model was based on spectral moments weighted with Gasteiger-Marsilli atomic charges, polarizability and hydrophobicity, as well as with Abraham indexes, specifically the summation solute hydrogen bond basicity and the combined dipolarity/polarizability. This is the first study to have explored the possibility of combining Abraham solute descriptors with spectral moments. A reasonable interpretation of these molecular descriptors from a toxicological point of view was achieved by means of taking into account bond contributions. The set of relationships so derived revealed the importance of the length of the alkyl chains for determining carcinogenic potential of the chemicals analysed, and were able to explain the difference between mono-substituted and di-substituted nitrosoureas as well as to discriminate between isomeric structures with hyminate between isomeric structures with hydroxyl-alkyl and alkyl substituents in different positions. Moreover, they allowed the recognition of structural alerts in classical structures of two potent nitrosamines, consistent with their biotransformation. These results indicate that this new approach has the potential for improving carcinogenicity predictions based on the identification of structural alerts

  19. Structure-activity relationship of immunomodulating pectins from elderberries.

    Science.gov (United States)

    Ho, Giang Thanh Thi; Ahmed, Abeeda; Zou, Yuan-Feng; Aslaksen, Torun; Wangensteen, Helle; Barsett, Hilde

    2015-07-10

    The berries of Sambucus nigra have traditionally been used and are still used to treat respiratory illnesses such as cold and flu in Europe, Asia and America. The aim of this paper was to elucidate the structures and the immunomodulating properties of the pectic polymers from elderberries. All the purified fractions obtained from 50% ethanol, 50°C water and 100°C water extracts showed potent dose-dependent complement fixating activity and macrophage stimulating activity. The isolated fractions consisted of long homogalacturonan regions, in addition to arabinogalactan-I and arabinogalactan-II probably linked to a rhamnogalacturonan backbone. Reduced bioactivity was observed after reduction of Araf residues and 1?3,6 Gal by weak acid hydrolysis. The rhamnogalacturonan region in SnBe50-I-S3-I and SnBe50-I-S3-II showed higher activity compared to the native polymer, SnBe50-S3, after enzymatic treatment with endo-?-d-(1?4)-polygalacturonase. These results indicated that elderberries contained immunomodulating polysaccharides, where the ramified regions express the activities observed. PMID:25857988

  20. Mullite Ceramics: Its Properties Structure and Synthesis

    Directory of Open Access Journals (Sweden)

    Juliana Anggono

    2005-01-01

    Full Text Available Besides its importance for conventional ceramics, mullite has become a choice of material for advanced structural and functional ceramics due to its favourable properties. Some outstanding properties of mullite are low thermal expansion, low thermal conductivity, excellent creep resistance, high-temperature strength, and good chemical stability. The mechanism of mullite formation depends upon the method of combining the alumina- and silica-containing reactants. It is also related to the temperature at which the reaction leads to the formation of mullite (mullitisation temperature. Mullitisation temperatures have been reported to differ by up to several hundred degrees Celsius depending on the synthesis method used. The three synthesis methods used to prepare mullite are discussed in this paper together with an overview of mullite, its properties and the current application of mullite. Abstract in Bahasa Indonesia : Keramik mullite tidak hanya penting dalam penggunaan konvensional, tetapi juga sudah menjadi bahan pilihan untuk aplikasi struktural dan fungsional karena sifat-sifatnya yang menguntungkan. Beberapa keunggulan sifat mullite adalah sifat muai dan konduktivitas panasnya rendah, ketahanan mulur yang tinggi, kekuatan yang terjaga pada temperatur tinggi, dan sifat korosinya yang baik. Mekanisme pembentukan mullite bergantung pada bagaimana proses menggabungkan reaktan yang mengandung alumina dan silika. Mekanisme tersebut juga bergantung pada temperatur reaksi awal yang akan mengarah pada pembentukan mullite (mullitisation. Beberapa penelitian melaporkan terjadinya temperatur mullitisation yang bervariasi hingga beberapa ratus derajat Celsius bergantung pada proses sintesa yang digunakan. Artikel ini menjelaskan tiga proses sintesa yang menghasilkan mullite yang dibahas bersama dengan sifat-sifat dan aplikasi mullite saat ini. Kata kunci: mullite, mullitisation, fasa glassy, sol-gel, spray pyrolysis, chemical vapour deposition.

  1. Structure - property relationships of films based on polyurethane water dispersions.

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Poreba, Rafal; Špírková, Milena

    Prague : Institute of Macromolecular Chemistry AS CR, 2014. P3. ISBN 978-80-85009-79-8. [Workshop "Career in Polymers" /6./. 18.07.2014-19.07.2014, Prague] R&D Projects: GA ?R(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : charge carrier mobility * conjugated polymer * Marcus theory Subject RIV: CD - Macromolecular Chemistry

  2. Structure{leftrightarrow}property relationships in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Huebner, W.; Reed, D.M.; Anderson, H.U. [Univ. of Missouri, Rolla, MO (United States)

    1996-12-31

    The electrode reactions are a major cause of the energy losses in SOFC`s, and limit their use to higher temperatures, typically 800-1000{degrees}C. The electrode reactions have received much attention aimed at better understanding the electrode kinetics and mechanisms, but are still very primitive in their basic understanding. The electrode microstructure and its corresponding reactivity has commonly been studied by DC and AC impedance techniques. A common method of examining electrode reactions employs surface-mounted reference electrodes, although this technique often limits the experiment to examination of one electrode. In this study a new technique has been developed of utilizing a Pt voltage probe placed internally into the electrolyte to measure the IN and impedance spectra of both electrodes operating under cell conditions. Unlike surface mounted electrodes which need to be concerned with distance and dimensions of reference electrodes with respect to working and counter electrodes the internal Pt voltage probe is centered internally at a known depth within the electrolyte and between corresponding electrodes.

  3. Quantitative study of the relationships among proteolysis, lipid oxidation, structure and texture throughout the dry-cured ham process.

    Science.gov (United States)

    Harkouss, Rami; Astruc, Thierry; Lebert, André; Gatellier, Philippe; Loison, Olivier; Safa, Hassan; Portanguen, Stéphane; Parafita, Emilie; Mirade, Pierre-Sylvain

    2015-01-01

    Temperature, salt and water contents are key processing factors in dry-cured ham production. They affect how proteolysis, lipid oxidation, structure and texture evolve, and thus determine the sensory properties and final quality of dry-cured ham. The aim of this study was to quantify the interrelationships and the time course of (i) proteolysis, (ii) lipid oxidation, (iii) five textural parameters: hardness, fragility, cohesiveness, springiness and adhesiveness and (iv) four structural parameters: fibre numbers, extracellular spaces, cross section area, and connective tissue area, during the dry-cured ham process. Applying multiple polynomial regression enabled us to build phenomenological models relating proteolysis, salt and water contents to certain textural and structural parameters investigated. A linear relationship between lipid oxidation and proteolysis was also established. All of these models and relationships, once combined with salt penetration, water migration and heat transfer models, can be used to dynamically simulate all of these phenomena throughout dry-cured ham manufacturing. PMID:25053089

  4. Relationships among Properties of College Students' Self-Set Academic Goals and Academic Achievement

    Science.gov (United States)

    Acee, Taylor W.; Cho, Yoonjung; Kim, Jung-In; Weinstein, Claire Ellen

    2012-01-01

    The major purpose of this study was to investigate the relationships among properties of college students' self-set academic goals and academic achievement, using multiple theoretical perspectives. Using a personal goal-based research methodology, college students enrolled in a learning-to-learn course (N = 130) were asked to list 20 of their…

  5. Psychometric properties of the Interpersonal Relationship Inventory with a homeless sample.

    Science.gov (United States)

    Frohlich, K L; Fournier, L

    1997-06-01

    This paper examined the psychometric properties of the Interpersonal Relationship Inventory with a sample of homeless men who were first-time shelter users. The measure, based on social exchange theory and equity theory, has two subscales, one for support and the other for conflict. As yet, few measurements have been developed to assess conflict from within social networks. As part of a larger longitudinal study a sample of 166 first-time shelter users was administered the inventory. A student sample also filled out the inventory for comparison purposes. Internal consistency for both subscales was good, .90 for Support and .83 for Conflict. Weak interitem correlations were prevalent among many items in the Conflict subscale. A nearly zero correlation was found between scores on the Support and Conflict subscales, suggesting independence. An exploratory factor analysis using varimax rotation confirmed a dual factor structure. Analyses of variance and Scheffé contrast tests detected no statistically significant differences between age groups on either the Support or the Conflict subscales. A multiple regression analysis indicated that, when controlling for age, scores on the Support scale discriminated the homeless and student samples, while scores on the Conflict subscale do not. The Support subscale indicates excellent psychometric qualities, while the Conflict subscale should be refined. PMID:9198389

  6. Highlighting the structure-function relationship of the brain with the Ising model and graph theory.

    Science.gov (United States)

    Das, T K; Abeyasinghe, P M; Crone, J S; Sosnowski, A; Laureys, S; Owen, A M; Soddu, A

    2014-01-01

    With the advent of neuroimaging techniques, it becomes feasible to explore the structure-function relationships in the brain. When the brain is not involved in any cognitive task or stimulated by any external output, it preserves important activities which follow well-defined spatial distribution patterns. Understanding the self-organization of the brain from its anatomical structure, it has been recently suggested to model the observed functional pattern from the structure of white matter fiber bundles. Different models which study synchronization (e.g., the Kuramoto model) or global dynamics (e.g., the Ising model) have shown success in capturing fundamental properties of the brain. In particular, these models can explain the competition between modularity and specialization and the need for integration in the brain. Graphing the functional and structural brain organization supports the model and can also highlight the strategy used to process and organize large amount of information traveling between the different modules. How the flow of information can be prevented or partially destroyed in pathological states, like in severe brain injured patients with disorders of consciousness or by pharmacological induction like in anaesthesia, will also help us to better understand how global or integrated behavior can emerge from local and modular interactions. PMID:25276772

  7. Quantitative Structure-Retention Relationship Study of Gas Chromatographic Retention Indices for Halogenated Compounds

    Directory of Open Access Journals (Sweden)

    Teodora Ivanciuc

    2002-02-01

    Full Text Available A high interest in predicting physical, chemical, and biological properties of halogenated compounds is generated by the urgent need to develop alternatives to chlorofluorocarbons, new compounds with low ozone depletion potential and a low global warming potential. Quantitative structure-retention relationships (QSRR for halogenated compounds can be used to predict gas chromatographic retention indices by using theoretical descriptors computed from the chemical structure. QSRR models for the gas chromatographic retention indices of 207 halogenated compounds are established with the CODESSA (Comprehensive Descriptors for Structural and Statistical Analysis program. The best results are obtained with a group of QSRR models with six structural descriptors, with a correlation coefficient between 0.994 and 0.993 and a leave-one-out cross-validation correlation coefficient between 0.992 and 0.991. All QSRR models contain the Kier and Hall connectivity index 1?v, the number of F atoms NoF, and the gravitation index for all pairs of atoms G1. A fourth descriptor comes from the class of charged-partial surface area indices, while the remaining two descriptors are related to the number of I or Br atoms, bond order, or Randic connectivity index 1?. QSRR models developed with CODESSA allow accurate computation of the gas chromatographic retention indexes of halogenated compounds using simple constitutional, topological, geometric, electrostatic and quantum descriptors that can be computed with standard quantum chemistry packages.

  8. Structure and properties of carbon nanofibers. application as electrocatalyst support

    Directory of Open Access Journals (Sweden)

    S. del Rio

    2012-03-01

    Full Text Available The present work aimed to gain an insight into the physical-chemical properties of carbon nanofibers and the relationship between those properties and the electrocatalytic behavior when used as catalyst support for their application in fuel cells.

  9. Microcellular wood-fibre thermoplastic composites: Processing-structure-properties

    Science.gov (United States)

    Doroudiani, Saeed

    In this study, processing-structure-property relationships in foamed wood-fibre plastic composites made with a physical blowing agent were investigated. For the polymers studied, it was found that the crystallinity and morphology have a critical effect on the foaming process. Therefore, an investigation of both semicrystalline and amorphous polymers was conducted. Several amorphous and semicrystalline polymers were selected, based on preliminary experimental results. By non-isothermal crystallisation of the semicrystalline polymers at various cooling rates, specimens with different crystallinities and crystal morphologies were made. The microstructures and sorption properties of these specimens were studied. All the specimens were foamed in a batch process using carbon dioxide as blowing agent and their structures were, investigated. The results showed a great influence of crystallinity and morphology on the solubility and diffusivity of the blowing agent in and through the polymer and especially on the cellular structure of the resulting foams. In contrast to the work of Colton (1989), who suggested that the foaming process should be conducted at a temperature above the melting point, it was shown that by controlling the crystallinity and crystal morphology it is feasible to produce microcellular foams from semicrystalline polymers in the solid state. In the second phase of the study, high density polyethylene and polystyrene were used as the matrices in a foamed wood-fibre composite. Sheets of composites were produced by compounding polymers and fibre. These samples were saturated with carbon dioxide at high pressure and the saturated specimens were foamed at elevated temperatures. Structural analysis and characterisation were performed on both foamed and unfoamed samples. The experimental results showed that the addition of wood fibre had very different effects on the mechanical properties of polystyrene (a glassy polymer) and polyethylene (a semicrystalline ductile polymer). Fibres acted as nucleating agents in the crystallisation of the matrix, and drastically changed the morphology. The impact strength of PS increased when wood fibres were added, while wood fibre diminished the impact strength of PE. The presence of wood fibres significantly changed the microstructure of the composite in the foaming process. Overall, while diminishing the tensile properties (strength and modulus), foaming caused a significant improvement of impact strength of the wood-fibre composites.

  10. The Influence of Personal Characteristics and Relationship Properties on Marital Support

    Directory of Open Access Journals (Sweden)

    Lesley L Verhofstadt

    2007-10-01

    Full Text Available Self-report data from 200 married couples were used to examine personal characteristics (i.e., extraversion, neuroticism, attachment-related anxiety and avoidance and relationship properties (i.e., intimacy, commitment, marital conflict, and marital satisfaction as determinants of supportive behaviours and perceptions of support availability within marital relationships. The data revealed that both personal and relational variables had important value in the prediction of support perceptions, support seeking, and support provision in marriage. Furthermore, relational predictors were found to explain more variability in spousal support than personal characteristics. Finally, results indicated that personal influences on support perceptions and support behaviours were less pronounced when relationship features were taken into account. In conclusion, the present research advocates in favour of a relationship perspective on social support in marriage.

  11. Fundamental Structure-Activity Relationships of Titanium Dioxide-Based Photocatalysts

    Science.gov (United States)

    Roberts, Charles A.

    Heterogeneous photocatalysis has been identified as a means of using renewable solar energy to produce the sustainable, non-carbon fuel H 2 and a variety of useful chemical intermediates. Currently, however, heterogeneous photocatalytic reactions are too inefficient to be industrially relevant and a deeper understanding of the effect of fundamental photocatalytic material properties on photoactivity is needed to further enhance the yields of desired products. In the general field of heterogeneous catalysis, structure-activity relationships aid in the rational design of improved catalysts and this ideology was applied to photocatalytic reactions over TiO2 based photocatalysts and model supported TiO2/SiO2 catalysts in this study. The model supported TiO2/SiO2 catalysts contain well-defined TiOx nanodomain structures that vary in domain size and electronic structure and greatly facilitate the determination of structure-photoactivity relationships. These catalysts were used in reactor studies during photocatalytic water splitting and cyclohexane photo-oxidation, and were monitored for production of H2 and cyclohexanone, respectively. It was found that for both reactions the trend in photoactivity for the TiOx nanodomains proceeded as: pure TiO2 (anatase) (24 nm) > TiO2 (anatase) nanoparticles (4--11 nm) > polymeric surface TiO5 (˜1 nm) > surface isolated TiO4 (˜0.4 nm). Photoluminescence (PL) spectroscopy was employed to yield insight into how exciton generation and recombination are related to TiOx domain size and, thus, to the photoactivity of the examined reactions. Transient PL decay studies determined that the larger bulk structure found in TiO 2 (anatase) nanoparticles (NPs) acts as a reservoir for excitons exhibiting slow recombination kinetics, which have an increased opportunity to participate in photochemistry at the surface active sites. The reactions were also studied using in situ attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR) to observe the formation of adsorbed intermediates and products. For cyclohexane photo-oxidation, cyclohexanone intermediates and products were identified and the high photoactivity of the unsupported TiO2 (anatase) NPs was attributed to improved product desorption characteristics. The identification of intermediates during water splitting is made difficult by the extremely high absorption of infrared wavelengths by H2O. ATR-FTIR and Raman spectroscopy measurements were performed during photocatalytic splitting of water in an attempt to confirm the surface reaction intermediates currently identified in the literature and evidence for both superoxide (O2-) and peroxide (O2 2-) adsorbed species were found by ATR-FTIR, but no surface Ti-OOH was detected by Raman. Finally, alternate Ti-containing structures, titanate and TiO2 (anatase) nanotubes, were characterized with Raman spectroscopy and screened for their photocatalytic activity. Depending on the photo-reaction (4-chlorophenol decomposition or water splitting), thermal treatment to form the anatase phase in the nanotubular structure is a benefit to photoactivity due to the increased crystallinity. For water splitting, however, the structure-activity relationship found for supported TiO 2/SiO2 holds, and the presence of a larger bulk structure yields the best H2 production photoactivity. The structure-photoactivity relationship in this dissertation exists for two different photo-reactions and is expected to be a beneficial aid to future studies on the rational design of new and novel photocatalysts.

  12. Thyroid hormone structure-activity relationships: molecular structure of 3,5,3'-triiodothyropropionic acid.

    Science.gov (United States)

    Cody, V

    1988-01-01

    The crystal and molecular structures of 3,5,3'-triiodothyropropionic acid (T3P), determined as an N-diethanolamine salt, were carried out and the results are compared with those of other thyroid hormone structures. These data show that T3P has an unusual conformation with the diphenyl ether bridge outside the range normally observed for other thyroactive acid structures and has the largest deviations from the ideal skewed conformation predicted for 3,5-diiodothyroactive compounds. These conformational properties are not observed in the structures of thyroformic or acetic acid analogues. Biochemical data indicate that thyropropionic acid analogue activity differs from that other acid analogues which could imply that their metabolism and activity can be controlled differently from that of other hormone metabolites. PMID:3168955

  13. Structural properties of sodium-iron phosphate glasses

    Science.gov (United States)

    Wang, Guomei; Wang, Yuan; Jin, Baohui

    1994-10-01

    The affects of iron on the structure, physical, and optical properties of several iron phosphate and sodium-iron phosphate glasses were investigated using x-ray photoelectron spectroscopy (XPS), Mossbauer spectroscopy, and infrared spectroscopy (IR). Archimedes method, differential scanning colorimeter and Able refractometer measurements were used to determine the glass density (d), transition temperature (Tg), and refractive index (n), respectively. XPS and Mossbauer spectra showed the presence of iron in both the Fe2+ and Fe3+(4- and 6-coordinated) states. With the increase of Fe2O3 content in the iron phosphate glasses and the increase of Na2O content in the sodium-iron phosphate glasses, the Fe2+/Fe ratio decreases and the Fe3+(4-coordinated)/Fe ratio increases. The infrared measurements showed that the increase in the Fe2O3 content or the Na2O content caused a change in coordination from FeO6 to FeO4. Finally, the relationship between the properties and the Fe2+Fe3+(4-coordination) ratio is discussed briefly.

  14. Electrical and dielectric properties of bovine trabecular bone - relationships with mechanical properties and mineral density

    International Nuclear Information System (INIS)

    Interrelationships of trabecular bone electrical and dielectric properties with mechanical characteristics and density are poorly known. While electrical stimulation is used for healing fractures, better understanding of these relations has clinical importance. Furthermore, earlier studies have suggested that bone electrical and dielectric properties depend on the bone density and could, therefore, be used to predict bone strength. To clarify these issues, volumetric bone mineral density (BMDvol), electrical and dielectric as well as mechanical properties were determined from 40 cylindrical plugs of bovine trabecular bone. Phase angle, relative permittivity, loss factor and conductivity of wet bovine trabecular bone were correlated with Young's modulus, yield stress, ultimate strength, resilience and BMDvol. The reproducibility of in vitro electrical and dielectric measurements was excellent (standardized coefficient of variation less than 1%, for all parameters), especially at frequencies higher than 1 kHz. Correlations of electrical and dielectric parameters with the bone mechanical properties or density were frequency-dependent. The relative permittivity showed the strongest linear correlations with mechanical parameters (r > 0.547, p vol (r 0.866, p vol were high properties or BMDvol were highest at frequencies over 6 kHz. In addition, a significant site-dependent variation of electrical and dielectric characteristics, mechanical properties and BMDvol was revealed in bovine femur (p < 0.05, Kruskall-Wallis H-test). Based on the present results, we conclude that the measurement of electrical and dielectric properties provides quantitative information that is related to bone quantity and quality

  15. Transcallosal sensorimotor fiber tract structure-function relationships

    OpenAIRE

    Fling, Brett W.; Benson, Bryan L.; Seidler, Rachael D.

    2011-01-01

    Recent studies have demonstrated neuroanatomically selective relationships between white matter tract microstructure, physiological function and task performance. Such findings suggest that the microstructure of transcallosal motor fibers may reflect the capacity for interhemispheric inhibition between the primary motor cortices, although full characterization of the transcallosal inhibitory sensorimotor network is lacking. Thus, the goal of the current study was to provide a comprehensive de...

  16. The synthesis: Structure relationship in the ZnO-Cr2O3 system

    Directory of Open Access Journals (Sweden)

    Man?i? Lidija T.

    2004-01-01

    Full Text Available In this work the development of the spinel phase in the ZnO-Cr2O3 system was discussed from the viewpoint of the synthesis-structure relationship. The nanostructure evolution in particles obtained either via solution-based (spray pyrolysis or solid-state (mechanical activation synthesis procedures were investigated by XRD analysis. A detailed structural analysis of the spinel phase lattice parameters, average primary crystallite sizes and micro strains were performed in accordance with a procedure based on the Koalariet-Xfit program. Due to the importance of spinel-phase cat ion distribution for chemical and physical properties, a study of the site occupation factors, i.e. changes in the stoichiometric, of ZnCr2O4 spinals was undertaken. The calculation based on atomistic methods for the description of both perfect and defect spinel ZnCr2O4 crystal lattices has been applied and the presence of individual structural defects was determined.

  17. Introducing Spectral Structure Activity Relationship (S-SAR Analysis. Application to Ecotoxicology

    Directory of Open Access Journals (Sweden)

    Ana-Maria Lacrămă

    2007-05-01

    Full Text Available A novel quantitative structure-activity (property relationship model, namelySpectral-SAR, is presented in an exclusive algebraic way replacing the old-fashionedmulti-regression one. The actual S-SAR method interprets structural descriptors as vectorsin a generic data space that is further mapped into a full orthogonal space by means of theGram-Schmidt algorithm. Then, by coordinated transformation between the data andorthogonal spaces, the S-SAR equation is given under simple determinant form for anychemical-biological interactions under study. While proving to give the same analyticalequation and correlation results with standard multivariate statistics, the actual S-SARframe allows the introduction of the spectral norm as a valid substitute for the correlationfactor, while also having the advantage to design the various related SAR models throughthe introduced “minimal spectral path” rule. An application is given performing a completeS-SAR analysis upon the Tetrahymena pyriformis ciliate species employing its reportedeco-toxicity activities among relevant classes of xenobiotics. By representing the spectralnorm of the endpoint models against the concerned structural coordinates, the obtainedS-SAR endpoints hierarchy scheme opens the perspective to further design the eco-toxicological test batteries with organisms from different species.

  18. Structure-activity relationship of berberine and derivatives acting as antifungal compounds

    Scientific Electronic Library Online (English)

    R. D., Enriz; M. L., Freile.

    2006-07-01

    Full Text Available Se presenta un estudio de correlación estructura-actividad de berberina y compuestos estructuralmente relacionados. Se modifico químicamente a berberina con el objeto de obtener canadina y oxiberberina. Se informa también la actividad antifúngica in vitro de bereberina, canadina, oxyberberina, lirio [...] denina, o-metil-mostachatolina y otros cuatro derivados. Nuestros resultados nos han permitido determinar los mínimos requerimientos estructurales para producir la respuesta antifúngica y pueden dar una guía para el diseño de nuevos compuestos con estas propiedades. Abstract in english A structure-activity relationship study of berberine and structurally related compounds is reported. Berberine, was chemically modified in order to obtain canadine and oxyberberine. The in vitro evaluation of antifungal activity of berberine, canadine, oxyberberine, liriodenine, o-methyl-mostachatol [...] ine and other four derivatives is also reported here. Our results allow us to determine the minimal structural requirements to produce the antifungal response and can provide a guide for the design of new compounds with these properties.

  19. Linear free energy relationship applied to trivalent cations with lanthanum and actinium oxide and hydroxide structure

    International Nuclear Information System (INIS)

    Linear free energy relationships for trivalent cations with crystalline M2O3 and, M(OH)3 phases of lanthanides and actinides were developed from known thermodynamic properties of the aqueous trivalent cations, modifying the Sverjensky and Molling equation. The linear free energy relationship for trivalent cations is as ?Gf,MvX0=aMvX?Gn,M3+0+bMvX+?MvXrM3+, where the coefficients aMvX, bMvX, and ?MvX characterize a particular structural family of MvX, rM3+ is the ionic radius of M3+ cation, ?Gf,MvX0 is the standard Gibbs free energy of formation of MvX and ?Gn,M3+0 is the standard non-solvation free energy of the cation. The coefficients for the oxide family are: aMvX=0.2705, bMvX=-1984.75 (kJ/mol), and ?MvX=197.24 (kJ/molnm). The coefficients for the hydroxide family are: aMvX=0.1587, bMvX=-1474.09 (kJ/mol), and ?MvX=791.70 (kJ/molnm).

  20. Modeling structural acoustic properties of loudspeaker cabinets

    DEFF Research Database (Denmark)

    Luan, Yu

    2011-01-01

    In this dissertation, a theoretical/numerical methodology is presented for coarse and fast predictions of cabinet vibrations. The study is focused on vibrations of rib-stiffened panels by improving a smearing technique and employing it into finite element modeling. The computationally efficient smearing technique for a cross-stiffened flat thin rectangular plate has been known for many years, but so far the accuracy of predicted natural frequencies has been inadequate. To improve predictions, all stiffeners including the ones neglected in the ordinary smearing technique are taken into account in the calculation of bending stiffness in this dissertation. The improved smearing technique results in good accuracy for predicted natural frequencies and forced vibrations of flat stiffened plates. Another improvement concerns the orientation of the stiffeners. The original smearing technique presupposes that the stiffeners are parallel to the edges of the plate, but simple considerations make it possible to relax this requirement. Whereas the improved smearing technique is well established for stiffened flat panels, there is no similar established technique for doubly curved stiffened shells. In an additional study, the improved smearing technique is combined with the equation of motion for a doubly curved thin rectangular shell, and a solution is offered for using the smearing technique for stiffened shell structures. Finally, the developed smearing technique is employed in a finite element modeling for estimating the vibrational properties and associated sound radiation of models including stiffened panels. Overall, the developed technique is found to be a good method for fast estimations of cabinet vibrations.

  1. Synthesis route and structural properties of nanoferrites

    International Nuclear Information System (INIS)

    The nano dimensional magnesium ferrite materials Mg0.25Fe2.75O4 , Mg0.5Fe2.5O4 and MgFe2O4 with different stoichiometry were prepared by co-precipitation procedure using MgCl2 •6H2O, FeCl2 •4H2O and FeCl3 •6H2O and NaOH as precipitant. The physicochemical methods - X-ray diffraction analysis, Moessbauer spectroscopy and FTIR spectroscopy were performed to investigate the structural properties of obtained nano size magnesium ferrite type samples. The registered experimental data were determined the presence of spinel ferrites and additional precursor phases as iron oxihydroxides and double layered hydroxides in ferrite materials MgxFe3-xO4 (x=0.5;1). In the case of magnesium ferrite sample MgxFe3-xO4 (x=0.25) the existence of non-stoichiometric spinel ferrite and intermediate phase - iron oxihydroxides were observed only. Key words: magnesium ferrites, co-precipitation, physicochemical methods

  2. Silicene oxides: formation, structures and electronic properties.

    Science.gov (United States)

    Wang, Rong; Pi, Xiaodong; Ni, Zhenyi; Liu, Yong; Lin, Shisheng; Xu, Mingsheng; Yang, Deren

    2013-01-01

    Understanding the oxidation of silicon has been critical to the success of all types of silicon materials, which are the cornerstones of modern silicon technologies. For the recent experimentally obtained two-dimensional silicene, oxidation should also be addressed to enable the development of silicene-based devices. Here we focus on silicene oxides (SOs) that result from the partial or full oxidation of silicene in the framework of density functional theory. It is found that the formation of SOs greatly depends on oxidation conditions, which concern the oxidizing agents of oxygen and hydroxyl. The honeycomb lattice of silicene may be preserved, distorted or destroyed after oxidation. The charge state of Si in partially oxidized silicene ranges from +1 to +3, while that in fully oxidized silicene is +4. Metals, semimetals, semiconductors and insulators can all be found among the SOs, which show a wide spectrum of electronic structures. Our work indicates that the oxidation of silicene should be exquisitely controlled to obtain specific SOs with desired electronic properties. PMID:24336409

  3. Record breaking properties for typical autocorrelation structures

    Science.gov (United States)

    Anagnostopoulou, Eirini; Galani, Andriani; Dimas, Panagiotis; Karanasios, Alexandros; Mastrotheodoros, Theodoros; Michaelidi, Eleni-Maria; Nikolopoulos, Dionisios; Pontikos, Stamatis; Sourla, Fani; Chazapi, Anna; Papalexiou, Simon Michael; Koutsoyiannis, Demetris

    2013-04-01

    Record-breaking occurrences in hydrometeorological processes are often used particularly in communicating information to the public and their analysis offers the possibility of better comprehending extreme events. However, the typical comprehension depends on prototypes characterized by pure randomness. In fact the occurrence of record breaking depends on the marginal distribution and the autocorrelation function of the process as well the length of available record. Here we study the influence of the process autocorrelation structure on the statistics of record-breaking occurrences giving emphasis on the differences with those of a purely random process. The particular stochastic processes, which we examine, are the AR(1), AR(2) and ARMA(1,1), as well as the Hurst-Kolmogorov process. The necessary properties are calculated using either analytical methods when possible or Monte Carlo simulation. We also compare the model results with observed hydrometeorological time series. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  4. How does servitization impact inter-organisational structure and relationships of a truck manufacturer's network?

    OpenAIRE

    Cakkol, Mehmet

    2013-01-01

    Network relationships play a significant role in the provision of servitized offerings. To date, little empirical research has been conducted to investigate the link between servitization and inter-organisational relationships. The objective of this doctoral thesis is to explore the implications of servitization on a manufacturer’s network. Particular emphasis is placed on the impact on the network structure and relationship attributes. An exploratory in-depth case study was conducted withi...

  5. Relationship between electrical and rheological properties of sewage sludge - Impact of temperature.

    Science.gov (United States)

    Ségalen, C; Dieudé-Fauvel, E; Clément, J; Baudez, J C

    2015-04-15

    Rheological properties are key criteria for sewage sludge management but are difficult to determine in situ. Because the literature often links rheological characteristics to surface charges of particles that interact, the underlying electrostatic interactions could be key characteristics explaining the rheological behavior of sludge. This paper analyzed the impact of temperature on both rheological and electrical properties. Both liquid and solid properties appear to be related to electrical impedance spectroscopy measurements because they obey the same relationships with the same activation energies. Infinite viscosity follows an Arrhenius law with temperature, whereas the storage modulus shows VTF (Vogel-Tamman-Fulcher) behavior. Sludge electrical behavior can be modeled by an equivalent 2-branch parallel circuit whose respective impedances follow Arrhenius and VTF relationships. More interestingly, resistors are proportional to (dissipative) viscous characteristics, whereas capacitances are proportional to the (storage) elastic modulus. These similarities and relationships underlie the same interactions that seem to be involved in both rheological and electrical properties. These interdependences are quite logical but open new insights into sludge characterization. PMID:25634652

  6. Optical properties of germanium dioxide in the rutile structure

    Science.gov (United States)

    Sahnoun, M.; Daul, C.; Khenata, R.; Baltache, H.

    2005-06-01

    We present first-principles calculations for the optical properties of germanium dioxide in the rutile structure. The electronic band structure has been calculated self-consistently within the local density approximation using the full-potential linearized augmented plane wave method. The electronic band structure shows that the fundamental energy gap is direct at the center of the Brillouin zone. The determinant role of a band structure computation with respect to the analysis of the optical properties is discussed.

  7. Assessment of Romantic Perfectionism: Psychometric Properties of the Romantic Relationship Perfectionism Scale

    Science.gov (United States)

    Matte, Melody; Lafontaine, Marie-France

    2012-01-01

    The objective of the present study was to provide validity evidence for the scores from the Romantic Relationship Perfectionism Scale. Results indicate a two-factor structure, adequate reliability, and overall good convergent, concurrent, discriminant, and incremental validity evidence. The strengths and limitations of this measure are discussed.…

  8. Social Structure-Personality: What is the Relationship Between Social Class and Child-Rearing Values

    Science.gov (United States)

    Lashbrook, Jeffrey

    The sociologist, Melvin Kohn, argued that people's locations in social structures, particularly the occupational structure, influenced the values they would stress for their children because variations in structural locations exposed them to different experiences. His research, however, was done some time ago. Much has changed in our social world since then. Does the original relationship still hold?

  9. Study on the relationship of physical-mechanical properties and microstructures of cohesive soil in the Laizhou Bay, China

    Science.gov (United States)

    Li, P.

    2013-12-01

    Microstructure is main factor that determines the physical-mechanical properties of soil, so study on microstructure of sediment has important significance for understanding its engineering properties. This paper takes the cohesive soil in Laizhou Bay as research object, studies about its physical-mechanical properties and microstructure, and analyses their relationship from the qualitative and quantitative aspects. The cohesive soil in Laizhou Bay is mainly muddy clay, with a small amount of mud and silty clay. On the whole, it has the characteristics of low water content, high density, low void ratio, low plasticity, low compressibility, high shear strength, high vane shear strength, and high miniature penetration resistance. According to the classification of Gao Guo Rui, we can divide the microstructures of the cohesive soil in the Laizhou Bay into the following three types: granular cementation structure, granular link-bond structure, flocculent link-bongd structure, the dominant types is flocculent link-bongd structure, soil with this structure has the characteristics of medium to high strength, low to medium porosity, low to medium compressibility. Microstructure can better reflect the characteristics of the physical-mechanical properties of cohesive soil. By using IPP image processing software, the microstructure images of cohesive soil in Laizhou Bay is processed and pore (particles) area, number, pore size (particle size), circumference, roundness and surface fractal dimension are extracted. The average pore and particle of granular cementation, granular link-bond, flocculent link-bongd structure reduces gradually, the number increases gradually, the shape becomes regular gradually. The engineering geological characteristics reflected by structural parameters indicate that, the water content, void ratio, compressibility of granular cementation, granular link-bond and flocculent link-bongd structure increases gradually, and the strength reduces gradually. Multiple linear regression analysis of the microstructural parameters and physical-mechanical properties indexes of cohesive soil in this area indicates that the physical indexes are mainly related to the parameters that characterize the pore size and number, the mechanical indexes not only affect by the size, number of pore, but also the geometry of pore.

  10. Body Mass Index, Perceived Health, and Happiness: Their Determinants and Structural Relationships

    Science.gov (United States)

    Cornelisse-Vermaat, Judith R.; Antonides, Gerrit; Van Ophem, Johan A. C.; Van Den Brink, Henriette Maassen

    2006-01-01

    The structural relationships between body mass index, perceived health and happiness have been studied in a survey of 700 native Dutch citizens. We found an indirect effect of body mass index on happiness, via perceived health. Age had an inverted U-shaped relationship with body mass index, and both education and smoking had a negative effect on…

  11. Structural Features of Sibling Dyads and Attitudes toward Sibling Relationships in Young Adulthood

    Science.gov (United States)

    Riggio, Heidi R.

    2006-01-01

    This study examined sibling-dyad structural variables (sex composition, age difference, current coresidence, position adjacency, family size, respondent and/or sibling ordinal position) and attitudes toward adult sibling relationships. A sample of 1,053 young adults (M age = 22.1 years) described one sibling using the Lifespan Sibling Relationship…

  12. Structures and physicochemical properties of molecular aggregates of lipids

    International Nuclear Information System (INIS)

    Structures and physicochemical properties of lipids such as fatty acids, alcohols, acylglycerols and steroids in their two- or three-dimensional states were studied through the measurements of surface pressure (?), surface-molecular area (A), vapor-pressure osmosis, radioactivity (R), self-diffusion coefficient (D), density, viscosity, near-infrared spectroscopy (NIR), 13C-NMR spin-lattice relaxation time (T1), ESR, SEM, DSC, X-ray diffraction and small-angle neutron scattering (SANS). Following results are obtained: (1) ?-A and R-A relationships indicate that the explanation, being widely believed, of the reaction occurred in the oleic acid or the trioleylglycerol monolayer on the aqueous KMnO4 solution is incorrect. (2) By using the LB film of 3H-labelled fatty acid, the upper limit of the neutrino mass was determined. In addition, by using the LB film of 14C-labelled fatty acid, a new type of crystal-transformation process was found, in which fatty-acid crystal transforms from its unstable state to its stable one by the transfer of the fatty acid molecules through the vapor phase. (3) Fatty acids always exist as their dimers in their liquid state and mostly in non-polar solvents; the dimers are the units of the molecular movements in the molten liquid and in solvents. T1 results clearly showed the internal molecular movements of the dimers. In addition, D and SANS results indicated that two differe SANS results indicated that two different kinds of fatty acids in their binary mixture make only each homodimers. (4) Furthermore, the study on the liquid structure of fatty acids such as cis-6-, cis-9-, cis-11-, trans-9-octadecenoic acids and stearic acid indicated that these fatty-acid dimers construct the clusters resemble to the smectic-liquid crystal in the liquid state. The clusters determine the physicochemical properties of the liquid of the fatty acid. (author)

  13. Structure and electronic properties of pure and nitrogen doped nanocrystalline tungsten oxide thin films

    Science.gov (United States)

    Vemuri, Venkata Rama Sesha Ravi Kumar

    Tungsten oxide (WO3) is a multifunctional material which has applications in electronics, sensors, optoelectronics, and energy-related technologies. Recently, electronic structure modification of WO3 to design novel photocatalysts has garnered significant attention. However, a fundamental understanding of nitrogen-induced changes in the structure, morphology, surface/ interface chemistry, and electronic properties of WO 3 is a prerequisite to producing materials with the desired functionality and performance. Also, understanding the effect of thermodynamic and processing variables is highly desirable in order to derive the structure-property relationships in the W-O/W-O-N material system. The present work was, therefore, focused on studying the effects of processing parameters on the microstructure, optical properties, electrical conductivity, and electronic structures of pure and nitrogen-doped (N-doped) WO3 films grown by sputter deposition. Efforts were made to understand the properties and phenomena of pure and N-doped WO3 at reduced dimensionality (i.e., nanoscale dimensions). The results and analyses indicate that the growth temperature (Ts) has a significant effect on the microstructure of WO3 films. The grain size increases from 9 to 50 nm coupled with a phase transformation in the following sequence: amorphous (a) to monoclinic (m) to tetragonal (t) with increasing Ts (25--500°C). The nanocrystalline t-WO 3 films exhibit a strong (001) texturing. The band gap narrowing from 3.25 to 2.92 eV with grain size occurs due to quantum confinement effects. Correlated with the structure and optical properties, electrical conductivity also increases. Physical properties such as thickness, grain size, and density are also sensitive to oxygen/ nitrogen partial pressure during W-O/W-O-N sample fabrications. A direct relationship between film density and band gap is evident in nanocrystalline t-WO3 films grown at various oxygen pressures. It is observed that nitrogen doping significantly influences the structure-property relationships. Crystallographic analysis revealed that excess nitrogen trapped in the WO 3 crystal lattice induces a t--m phase transformation. The unique approach adopted in this work indicates a structure-dependent optical band gap variation leading to the lowest optical band gap (˜2.14 eV) at 0.7 at.% of N incorporation into t-WO3 films. The results clearly provide evidence to tune the electronic structure and properties with controlled N doping coupled with specific phase stabilization of WO3. The results provide a road map to phase-controlled synthesis of pure and Ndoped nanocrystalline WO3 films with desired properties.

  14. Quantitative structure-activity relationship of Morita-Baylis-Hillman adducts with leishmanicidal activity.

    Science.gov (United States)

    de Souza, Rodrigo Octavio M A; Barros, José C; da Silva, Joaquim F M; Antunes, Octavio A C

    2011-01-01

    A quantitative structure-activity relationship model for Morita-Baylis-Hillman adducts with leishmanicidal activities was developed which correlates molecular orbital energy and dipole with percentage in the promastigote stage. PMID:21630587

  15. 3D Printers Can Provide an Added Dimension for Teaching Structure-Energy Relationships

    Science.gov (United States)

    Blauch, David N.; Carroll, Felix A.

    2014-01-01

    A 3D printer is used to prepare a variety of models representing potential energy as a function of two geometric coordinates. These models facilitate the teaching of structure-energy relationships in molecular conformations and in chemical reactions.

  16. Changing structure of income indoor air pollution relationship in India

    International Nuclear Information System (INIS)

    Bio fuels are still a major source for cooking by many households in developing countries such as India causing significant disease burden due to indoor air pollution. While household income influences the choice of fuel the policies that affect accessibility and price of fuels also have an important role in determining the fuel choice. This study analyzes the pollution-income relationship for the period 1983-2000, separately across rural and urban households in India based on unit record data on fuel consumption obtained through National Sample Surveys. While a non-monotonic relationship is observed in rural India in both the decades, in urban India a similar relationship is observed only for the initial period indicating faster transition towards 'cleaner' fuels mainly enabled by policies that have been pro-urban. The study also finds that the impact of household size and composition on bio fuels is more negative than for clean fuels and is increasingly negative over time possibly due to greater awareness about the ill effects of such fuels

  17. Structure of vitreous body and its relationship with liquefaction

    OpenAIRE

    Makoto Kodama; Toyoaki Matsuura; Yoshiaki Hara

    2013-01-01

    The aim of the study is to clarify the vitreous body structure and liquefaction phenomena. It was found that when melting a frozen rabbit vitreous body, the gel-sol transition phenomenon occurs and the gel structure is broken. This is almost like the liquefaction of the vitreous body in vivo. We try to clarify the liquefaction phenomenon by using this animal model. The native vitreous body has three dimensional meshwork structures. After liquefaction, it is changed into two parts, namely fib...

  18. Effect of surfactant structure on properties of oil/water interfaces : A coarse-grained molecular simulation study.

    OpenAIRE

    Rekvig, Live

    2004-01-01

    The elastic properties of oil/water/surfactant interfaces play an important role in the phase behaviour of microemulsions and for the stability of macroemulsions. The aim of this thesis is to obtain an understanding of the relationship between the structure of the surfactant molecules, the structure of the interface, and macroscopic interfacial properties. To achieve this aim, we performed molecular simulations of oil/water/surfactant systems. We made a quantitative comparison of various mo...

  19. Design of Hybrid Solid Polymer Electrolytes: Structure and Properties

    Science.gov (United States)

    Bronstein, Lyudmila M.; Karlinsey, Robert L.; Ritter, Kyle; Joo, Chan Gyu; Stein, Barry; Zwanziger, Josef W.

    2003-01-01

    This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.

  20. The Relationship between Work-Family Conflict and Job Satisfaction: A Structural Equation Modeling (SEM) Approach

    OpenAIRE

    Nilgün Anafarta

    2011-01-01

    The aim of this study is to investigate the relationship between work-family conflict, family-work conflict andjob satisfaction using structural equation modeling. The data is obtained from 226 health service staff (doctorsand nurses) in Turkey. Considering the findings, it is concluded that health employees experience work-familyconflict more than they experience family-work conflict. Results obtained from the structural equation modelingindicate that there is a reciprocal relationship betwe...

  1. Species interactions–area relationships: biological invasions and network structure in relation to island area

    OpenAIRE

    Sugiura, Shinji

    2010-01-01

    The relationship between species number and island area is a fundamental rule in ecology. However, the extent to which interactions with exotic species and how the structure of species interactions is related to island area remain unexplored. Here, I document the relationship between island area and (i) interactions with exotic species and (ii) network structure of species interactions in the context of mutualistic interactions between ants and extrafloral nectary-bearing plants on the oceani...

  2. The Integrative Structure and Outcome Model of Relationship Benefits: Using Data Mining

    OpenAIRE

    Qingmin Kong; Mingli Zhang

    2011-01-01

    In recent years, the concept of relationship benefits has attracted increasing attention among marketing researchers and practitioners. Despite a growing body of literature in this area, no generally accepted integrative structure model and outcome model have emerged from the marketing literature. The present paper uses data mining to investigate the structure of relationship benefits based on the theoretical foundations of relational bonds, then, establishes the integrative outcome model. It...

  3. Molecular Descriptors Family on Structure Activity Relationships 1. Review of the Methodology

    OpenAIRE

    Ja?ntschi, Lorentz

    2005-01-01

    This review cumulates the knowledge about the use of Molecular Descriptors Family usage on Structure Activity Relationships. The methodology is augmented through the general Structure Activity Relationships methodology. The obtained models in a series of five papers are quantitatively analyzed by comparing with previous reported results by using of the correlated correlations tests. The scores for a series of 13 data sets unpublished yet results are presented. Two unrestricted online access p...

  4. Microstructure property relationships in prealloyed Ti-6Al-4V for gas turbine applications

    International Nuclear Information System (INIS)

    Recent advances in prealloyed titanium powder metallurgy offer the potential for cost-effective processing and have made it possible to produce fully dense components with mechanical properties at least equivalent to those found in wrought titanium. The present work focuses on the microstructure/property relationships in PREP (plasma rotating electrode process) Ti-6Al-4V powder. The mechanism of microstructural formation during hot isostatic pressing (HIP) has been examined, and the possibility of microstructural modification has been demonstrated. Processing of powder has resulted in the ability to produce controlled microstructures. 16 references

  5. Microstructure/property relationships in prealloyed Ti-6Al-4V for gas turbine applications

    International Nuclear Information System (INIS)

    Recent advances in prealloyed titanium powder metallurgy offer the potential for cost-effective processing and have made it possible to produce fully dense components with mechanical properties at least equivalent to those found in wrought titanium. The present work focuses on the microstructure/property relationships in PREP (plasma rotating electrode process) Ti-6Al-4V powder. The mechanism of microstructural formation during hot isostatic pressing (HIP) has been examined, and the possibility of microstructural modification has been demonstrated. Processing of powder has resulted in the ability to produce controlled microstructures. 16 references

  6. Microstructure property relationships in prealloyed Ti-6Al-4V for gas turbine applications

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, G.I.; Moxson, V.S.

    1986-02-01

    Recent advances in prealloyed titanium powder metallurgy offer the potential for cost-effective processing and have made it possible to produce fully dense components with mechanical properties at least equivalent to those found in wrought titanium. The present work focuses on the microstructure/property relationships in PREP (plasma rotating electrode process) Ti-6Al-4V powder. The mechanism of microstructural formation during hot isostatic pressing (HIP) has been examined, and the possibility of microstructural modification has been demonstrated. Processing of powder has resulted in the ability to produce controlled microstructures. 16 references.

  7. 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 phio as a more accurate hydrophobicity descriptor than Rmw. Phio is negatively correlated with theoretically calculated density, surface tension, and refractive index for the molecules. These models could be used to predict toxicity (absorption, distribution, metabolism, excretion, toxicity; ADMET) properties of the azo dyes and may also play useful roles in computer-assisted molecular discovery of nontoxic azo dyes. PMID:17373463

  8. Structural relationships in rhombohedral perovskites with R-3C symmetry

    International Nuclear Information System (INIS)

    In rhombohedral perovskites the structure parameters, e.g. the interaxial angle alpha/sub rh/ or the hexagonal lattice parameters a/sub H/ and c/sub H/ are completely determined by the tilt angle omega. The geometrical relations between these structural parameters and the tilt angle omega are reported

  9. Computer-aided visualization of database structural relationships

    International Nuclear Information System (INIS)

    Interactive computer graphic displays can be extremely useful in augmenting understandability of data structures. In complexly interrelated domains such as bibliographic thesauri and energy information systems, node and link displays represent one such tool. This paper presents examples of data structure representations found useful in these domains and discusses some of their generalizable components. 2 figures

  10. Engineering of Metal Microstructures; Process-Microstructure-Property Relationships for Electrodeposits

    DEFF Research Database (Denmark)

    Jensen, Jens Dahl

    2002-01-01

    The relationships between growth-conditions, topography and microstructure, and physical properties of electrochemically deposited copper, nickel and zinc-iron alloys were studied. Growth was investigated while systematically varying process parameters such as electrolyte chemistry, type and concentration of additives, current density, and mass transport. The grown films were analysed by a variety of characterisation techniques - including optical light microscopy, electron microscopy, atomic force microscopy, X-ray diffraction, thin film tensile testing, and nano-indentation. Studies of anomalous Zn-Fe alloy electrodeposition from a chloride-based electrolyte, suggest that a zinc-chloro-hydroxy-precipitate layer forms close to the cathode during deposition. Deposition current density, as well as the chloride-content of the electrolyte, controls the stability of the corresponding boundary layer at the cathode and hereby the composition of the deposited Zn-Fe alloy. Alloys with Fe-contents ranging from 5-80 wt-% were deposited from the same electrolyte, characterised by a sharp change in deposit-composition with electrochemical current density, which made the deposition of well-defined Zn-Fe compositionally modulated alloys (CMA) possible. Ni membranes were deposited from a Watts type electrolyte with or without the sulphur-containing additive sodium-saccharin. This additive caused a strong levelling as well as a grain refining effect on Ni-deposits. However, additional microstructural defects were introduced in the deposits with the use of sodium-saccharin, which led to embrittlement of the deposits. By using ultrasonic streaming near the cathode during electrodeposition in the Watts type electrolyte, improved material distribution in machined 3-dimensional groove geometries was observed. Electrochemical deposition of buried contacts for high efficiency silicon photovoltaic cells led to the development of a patented process for superconformal Cu-filling of high aspect ratio vias, while further studies on electrochemical Cu-deposition from acidic electrolytes led to the formulation of a 3-dimensional zone-structure diagram for electrodeposited Cu.

  11. Affine invariant texture analysis based on structural properties

    OpenAIRE

    Zhang, JianGuo; Tan, Tieniu

    2002-01-01

    This paper presents a new texture analysis method based on structural properties. The texture features extracted using this algorithm are invariant to affine transform (including rotation, translation, scaling, and skewing). Affine invariant structural properties are derived based on texel areas. An area-ratio map utilizing these properties is introduced to characterize texture images. Histogram based on this map is constructed for texture classification. Efficiency of this algorithm for affi...

  12. Electronic structure and properties of rare earth and actinide intermetallics

    International Nuclear Information System (INIS)

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

  13. Structural Polymer-Based Carbon Nanotube Composite Fibers: Understanding the Processing–Structure–Performance Relationship

    Directory of Open Access Journals (Sweden)

    Marilyn L. Minus

    2013-06-01

    Full Text Available Among the many potential applications of carbon nanotubes (CNT, its usage to strengthen polymers has been paid considerable attention due to the exceptional stiffness, excellent strength, and the low density of CNT. This has provided numerous opportunities for the invention of new material systems for applications requiring high strength and high modulus. Precise control over processing factors, including preserving intact CNT structure, uniform dispersion of CNT within the polymer matrix, effective filler–matrix interfacial interactions, and alignment/orientation of polymer chains/CNT, contribute to the composite fibers’ superior properties. For this reason, fabrication methods play an important role in determining the composite fibers’ microstructure and ultimate mechanical behavior. The current state-of-the-art polymer/CNT high-performance composite fibers, especially in regards to processing–structure–performance, are reviewed in this contribution. Future needs for material by design approaches for processing these nano-composite systems are also discussed.

  14. Cucurbitane Glycosides Derived from Mogroside IIE: Structure-Taste Relationships, Antioxidant Activity, and Acute Toxicity

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2014-08-01

    Full Text Available Mogroside IIE is a bitter triterpenoid saponin which is the main component of unripe Luo Han Guo fruit and a precursor of the commercially available sweetener mogroside V. In this study, we developed an enzymatic glycosyl transfer method, by which bitter mogroside IIE could be converted into a sweet triterpenoid saponin mixture. The reactant concentration, temperature, pH and buffer system were studied. New saponins with the ?-glucose group were isolated from the resulting mixtures, and the structures of three components of the extract were determined. The structure-taste relationships of these derivatives were also studied together with those of the natural mogrosides. The number and stereoconfiguration of glucose groups present in the mogroside molecules were found to be the main factor to determine the sweet or bitter taste of a compound. The antioxidant and food safety properties were initially evaluated by their radical scavenging ability and via 7 day mice survival tests, respectively. The results showed that the sweet triterpenoid saponin mixture has the same favorable physiological and safety characteristics as the natural mogrosides.

  15. Structure and function relationship in the abdominal stretch receptor organs of the crayfish.

    Science.gov (United States)

    Purali, Nuhan

    2005-08-01

    The structure/function relationship in the rapidly and slowly adapting stretch receptor organs of the crayfish (Astacus leptodactylus) was investigated using confocal microscopy and neuronal modeling methods. Both receptor muscles were single muscle fibers with structural properties closely related to the function of the receptors. Dendrites of the rapidly adapting neuron terminated in a common pile of nerve endings going in all directions. Dendrites of the slowly adapting neuron terminated in a characteristic T shape in multiple regions of the receptor muscle. The slowly adapting main dendrite, which was on average 2.1 times longer and 21% thinner than the rapidly adapting main dendrite, induced larger voltage attenuation. The somal surface area of the slowly adapting neuron was on average 51% larger than that of the rapidly adapting neuron. Variation in the neuronal geometry was greatest among the slowly adapting neurons. A computational model of a neuron pair demonstrated that the rapidly and the slowly adapting neurons attenuated the dendritic receptor potential like low-pass filters with cut-off frequencies at 100 and 20 Hz, respectively. Recurrent dendrites were observed mostly in the slowly adapting neurons. Voltage signals were calculated to be propagated 23% faster in the rapidly adapting axon, which is 51% thicker than the slowly adapting axon. The present findings support the idea that the morphology of the rapidly and the slowly adapting neurons evolved to optimally sense the dynamic and the static features of the mechanical stimulus, respectively. PMID:15973677

  16. Relationship between magnetic structure and ferroelectricity of systems with CuO 2 ribbon chains

    Science.gov (United States)

    Masatoshi, Sato; Yukio, Yasui; Yoshiaki, Kobayashi; Kenji, Sato; Yutaka, Naito; Yasuko, Tarui; Yuji, Kawamura

    2010-05-01

    Results of experimental studies carried out by various methods on systems with CuO 2 ribbon chains are presented. For LiVCuO 4, which was found to have helimagnetic and ferroelectric simultaneous transitions (multiferroic transitions), the relationship between the magnetic structure and the ferroelectricity is described in detail by showing their magnetic field dependences. For Li 2ZrCuO 4, NMR studies have revealed that the system has ac-helical magnetic structure. However, we have not observed the ferroelectricity in this ordered phase. This result suggests that there may exist the antiferro-type ordering, for example, of the helical axis vectors, of the CuO 2 chains. Several new findings are also shown on the magnetic and dielectric properties of other ribbon chain systems, LiVCuO 4, Li 2ZrCuO 4, LiCu 2O 2 and NaCu 2O 2 and a related system Na 2Cu 3(GeO 3) 4.

  17. Study of transport properties of bodies with a perovskite structure: application to the MgSiO3 perovskite

    International Nuclear Information System (INIS)

    After some recalls on transport in ionic solids (Nernst-Einstein relationship, variation of ionic conductivity, hybrid conduction, fast ionic conduction), this research thesis presents the physical properties of perovskites and more particularly the structure and stability of the MgSiO3 perovskite: structure and elastic properties, electric conductivity and transport properties in compounds with a perovskite structure. Then, the author reports the experimental study of the KZnF3 perovskite (a structural analogous of MgSiO3): measurements of electric conductivity under pressure, measurements under atmospheric pressure, result discussion. The next part addresses the numerical simulation of MgSiO3: simulation techniques (generalities on molecular dynamics, model description), investigation of structural, elastic and thermodynamic properties, diffusion properties in quadratic phase

  18. USING STRUCTURAL EQUATION MODELING TO INVESTIGATE RELATIONSHIPS AMONG ECOLOGICAL VARIABLES

    Science.gov (United States)

    This paper gives an introductory account of Structural Equation Modeling (SEM) and demonstrates its application using LISREL< with a model utilizing environmental data. Using nine EMAP data variables, we analyzed their correlation matrix with an SEM model. The model characterized...

  19. The Quest for Relationships between Conformation and Chiroptical Properties: From Solution to Solid State

    Scientific Electronic Library Online (English)

    Ernesto, Brunet; Hussein M.H., Alhendawi; Olga, Juanes; Juan Carlos, Rodríguez-Ubis.

    2009-09-01

    Full Text Available El enorme interés por los problemas estereoquímicos de toda índole mostrado por el tristemente desaparecido Prof. Ernest Ludwig Eliel ha dado lugar, no sólo a su larga y notoria lista de publicaciones, libros y conferencias, sino al no menos importante hecho de dejar la huella de su preocupación en [...] muchos de los que tuvimos la enorme suerte de trabajar con él. En este trabajo describimos cómo Ernest sembró en uno de nosotros la necesidad de buscar relaciones entre propiedades conformacionales y quirópticas. La semilla fue una molécula sencilla, el S-óxido del cis-3-hidroxitiano, en la que mostramos que la rotación específica en cualquier posición de su equilibrio conformacional es una media ponderada de la rotación específica de las conformaciones individuales. En el presente estamos dedicados a la construcción de estructuras sólidas. La unión de fosfonatos ópticamente puros entre las capas del ?-fosfato de zirconio da lugar a quiralidad a nivel supramolecular. Hemos mostrado que los términos conformación y propiedades quirópticas también están íntimamente relacionados en el estado sólido. Abstract in english The enormous interest of the late Prof. Ernest Ludwig Eliel for stereochemical problems has led not only to his publication of a impressively long list of papers, books and countless invitations for keynote lectures at conferences, but has stimulated a similar interest in this field among the many w [...] ho have had the opportunity to work with him. Ernest's seed on one of us turn out in the quest for new relationships between conformation and chiroptical properties. The germ was a simple molecule, cis-3-hydroxythiane S-oxide, that enabled us to show that the specific rotation at any position of its conformational equilibrium is a weighted average of the specific rotation of the individual conformations. We are now currently involved in the challenging task of the controlled building of solid structures from bottom-up approaches. To this end we have covalently attached optically pure phosphonates within the layers of ?-zirconium phosphate leading to chirality at the supramolecular level. We have shown that conformation and chiroptical properties are also strongly intertwined in the solid state.

  20. An examination of a reciprocal relationship between network governance and network structure

    DEFF Research Database (Denmark)

    Bergenholtz, Carsten; Goduscheit, René Chester

    2011-01-01

    In the present article, we examine the network structure and governance of inter-organisational innovation networks over time. Network governance refers to the issue of how to manage and coordinate the relational activities and processes in the network while research on network structure deals with the overall structural relations between the actors in the network. These streams of research do contain references to each other but they mainly rely on a static conception of the relationship between network structure and the applied network governance. Based on a case study of a loosely coupled Danish inter-organisational innovation network, the proposition is that a reciprocal relationship between network governance and network structure can be identified. Such a reciprocal relationship involves theoretical and practical implications for how to govern an inter-organisational network.

  1. Croatian banking sector research: relationship between ownership structure, concentration, owners’ type and bank performance

    Directory of Open Access Journals (Sweden)

    Igor Tomi?i?

    2012-12-01

    Full Text Available Banks are important financial intermediaries of any national economy, and corporate governance has an important role in banking sector; especially due to processes of the globalization and the internationalization, and also because of the sensitivity of the activities between the interest groups. The objective of this paper is to examine the relationship between ownership structure, concentration, owners’ type and bank performance. The authors made a research of banks' ownership structure using publicly available data. Using statistical tools authors discovered relationships between bank ownership structure and bank performance indicators (average asset, total asset, average equity, profit (loss before taxes, profit (loss after taxes, ROAA, ROAE. Further they discuss the relationships between ownership structure and a number of consequences for the bank performance. The authors discovered significant correlation between bank ownership structure and performance indicators variables that are described in the paper.

  2. Representation of molecular structure using quantum topology with inductive logic programming in structure-activity relationships.

    Science.gov (United States)

    Buttingsrud, Bård; Ryeng, Einar; King, Ross D; Alsberg, Bjørn K

    2006-06-01

    The requirement of aligning each individual molecule in a data set severely limits the type of molecules which can be analysed with traditional structure activity relationship (SAR) methods. A method which solves this problem by using relations between objects is inductive logic programming (ILP). Another advantage of this methodology is its ability to include background knowledge as 1st-order logic. However, previous molecular ILP representations have not been effective in describing the electronic structure of molecules. We present a more unified and comprehensive representation based on Richard Bader's quantum topological atoms in molecules (AIM) theory where critical points in the electron density are connected through a network. AIM theory provides a wealth of chemical information about individual atoms and their bond connections enabling a more flexible and chemically relevant representation. To obtain even more relevant rules with higher coverage, we apply manual postprocessing and interpretation of ILP rules. We have tested the usefulness of the new representation in SAR modelling on classifying compounds of low/high mutagenicity and on a set of factor Xa inhibitors of high and low affinity. PMID:17054018

  3. Quantitative structure carcinogenicity relationship for detecting structural alerts in nitroso-compounds

    International Nuclear Information System (INIS)

    Prevention of environmentally induced cancers is a major health problem of which solutions depend on the rapid and accurate screening of potential chemical hazards. Lately, theoretical approaches such as the one proposed here - Quantitative Structure-Activity Relationship (QSAR) - are increasingly used for assessing the risks of environmental chemicals, since they can markedly reduce costs, avoid animal testing, and speed up policy decisions. This paper reports a QSAR study based on the Topological Substructural Molecular Design (TOPS-MODE) approach, aiming at predicting the rodent carcinogenicity of a set of nitroso-compounds selected from the Carcinogenic Potency Data Base (CPDB). The set comprises nitrosoureas (14 chemicals), N-nitrosamines (18 chemicals) C-nitroso-compounds (1 chemical), nitrosourethane (1 chemical) and nitrosoguanidine (1 chemical), which have been bioassayed in male rat using gavage as the route of administration. Here we are especially concerned in gathering the role of both parameters on the carcinogenic activity of this family of compounds. First, the regression model was derived, upon removal of one identified nitrosamine outlier, and was able to account for more than 84% of the variance in the experimental activity. Second, the TOPS-MODE approach afforded the bond contributions - expressed as fragment contributions to the carcinogenic activity - that can be interpreted and provide tools for better understanding the mechanisms of carcinogenenderstanding the mechanisms of carcinogenesis. Finally, and most importantly, we demonstrate the potentialities of this approach towards the recognition of structural alerts for carcinogenicity predictions

  4. Structural and Interfacial Properties of Hyperbranched-Linear Polymer Surfactant.

    Science.gov (United States)

    Qiang, Taotao; Bu, Qiaoqiao; Huang, Zhaofeng; Wang, Xuechuan

    2014-01-01

    With oleic acid grafting modification, a series of hyperbranched-linear polymer surfactants (HLPS) were prepared by hydroxyl-terminated hyperbranched polymer (HBP), which was gained through a step synthesis method using trimethylolpropane and AB2 monomer. The AB2 monomers were obtained through the Michael addition reaction of methyl acrylate and diethanol amine. The structures of HLPS were characterised by Fourier transform infrared spectrophotometer and nuclear magnetic resonance (NMR), which indicated that HBP was successfully modified by oleic acid. Furthermore, the properties of surface tension and critical micelle concentration of HLPS solution showed that HLPS can significantly reduce the surface tension of water. The morphology of the HLPS solution was characterised by dynamic light scattering, which revealed that HLPS exhibited a nonmonotonic appearance in particle size at different scattering angles owing to the different replaced linear portions. The relationships of the surface pressure to monolayer area and time were measured using the Langmuir-Blodgett instrument, which showed that the surface tension of monolayer molecules increased with the increasing of hydrophobic groups. In addition, the interface conditions of different replaced HLPS solutions were simulated. PMID:25152609

  5. Structure-function relationships of autotaxin, a secreted lysophospholipase D.

    Science.gov (United States)

    Hausmann, Jens; Perrakis, Anastassis; Moolenaar, Wouter H

    2013-01-01

    Autotaxin (ATX or ENPP2) is an ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) that functions as a secreted lysophospholipase D to produce the multifunctional lipid mediator lysophosphatidic acid (LPA) from more complex lysophospholipids. LPA acts on distinct G protein-coupled receptors thereby activating multiple signaling cascades and cellular responses. The ATX-LPA signaling axis is implicated in a remarkably wide variety of physiological and pathological processes, ranging from vascular and neural development to lymphocyte homing, fibrosis and cancer. Despite much progress in understanding LPA receptor signaling, the precise mode of action of ATX has long remained elusive due to the lack of structural data. In particular, it has been unclear what makes ATX a unique lysophospholipase D and how the enzyme is targeted to LPA-responsive cells. Recent structural studies have begun to clarify these issues. Here we discuss new insights and inferences from the ATX structure. PMID:23069371

  6. Microstructure - property relationship in 22 mm thick X80 coil skelp

    Energy Technology Data Exchange (ETDEWEB)

    Liebeherr, M.; Bernier, N. [ArcelorMittal Global RnD Ghent, Zelzate, (Belgium); Ilic, N. [ArcelorMittal Bremen, Bremen, (Germany); Lebre, D.; Quidort, D. [ArcelorMittal Fos-sur-Mer, Fos-sur-Mer, (France)

    2010-07-01

    ArcelorMittal is looking for improving the low temperature toughness at heavy gauges. To understand the relationship between microstructure and toughness is crucial for future improvements. The study investigated the microstructure by performing two trials coils of different properties. These two coil samples are two industrially hot rolled X80 steels with thickness 21.6 mm. Battelle drop weight tear (BDWTT) tests and Charpy tests have been performed at different positions in the cross section, to determine the mechanical properties of the both coils. The quantification of the grain size and the observation of the texture were conducted using electron backscattering diffractaction (EBSD). The microstructure is fairly homogeneous over the cross section. A relation between the tensile strength and the Hall-Petch effect has been found, but a relation between the mean grain size and the toughness properties could not be found.

  7. On the relationship between the properties and the microstructure of multiphase materials

    International Nuclear Information System (INIS)

    The electrical resistivity, Youngs modulus of elasticity and the thermal expansion coefficient of multiphase materials depend on their microstructure, that is on the geometry and geometrical arrangement of their phases. The present contribution in four parts deals with the derivation and experimental confirmation of quantitative relationships between properties and microstructure. It is introduced by summarizing the state-of-the-art to the problem and considering the microstructure description quantitatively from data measured by quantitative microstructural analysis. The derivation of microstructure-property-equations follows providing the interrelationship between the microstructure of two phase materials including porous materials and their electrical resistivity, Youngs modulus of elasticity and thermal expansion coefficient. Calculated properties are compared to those measured for two phase materials including porous materials. (orig./WBU)

  8. Relationship between free volume and mechanical properties of polyurethane irradiated by gamma rays

    International Nuclear Information System (INIS)

    Polyurethane was irradiated at various gamma radiation doses up to 1,000 kGy at room temperature in nitrogen. Positron annihilation lifetime spectroscopy, tensile test and dynamic mechanical analysis were used to find the relationship between free volume and mechanical properties. An increase of the free volume fraction in soft segments (SS) and a decrease of the free volume fraction in hard segments (HS) during gamma radiation was observed and analyzed. The results showed that HS in polyurethane had the excellent resistance to gamma radiation, whereas SS had a tendency to degrade. The reason for the decrease of the strain at break and the ultimate tensile strength was analyzed, which showed the changes in the mechanical properties of polyurethane irradiated by gamma rays were mainly determined by the changes of free volume in SS. If the resistance properties of polyurethanes exposed to radiations need to be improved, SS should be paid more attention to. (author)

  9. Simulating liquid water for determining its structural and transport properties

    International Nuclear Information System (INIS)

    Molecular dynamics simulations are carried out for calculating structural and transport properties of pure liquid water, such as radial distribution functions and self-diffusion and viscosity coefficients, respectively. We employed reparameterized versions of the ab initio water potential by Niesar, Clementi and Corongiu (NCC). In order to investigate the role of the electrostatic contribution, the partial charges of the NCC model are adjusted so that to reproduce the dipole moment values of the SPC/E, SPC/Fw and TIP4P/2005 water models. The single and collective transport coefficients are obtained by employing the Green–Kubo relations at various temperatures. Additionally, in order to overcome convergence difficulties arising from the long correlation times of the stress-tensor autocorrelation functions, a previously reported fitting scheme was employed. The present results indicate that there is a significant relationship between the dipole moment value of the model, and the calculated transport coefficients. We found that by adjusting the molecular dipole moment of the NCC to the value of the TIP4P/2005, the obtained values for the self-diffusion and viscosity coefficients are in better agreement with experiment, compared to the values obtained with the original NCC model. Even though the predictions of the present model exhibits an overall correct behavior, we conclude that further improvements are still required. In order to achieve that, a careful reparameterization of the repulsion–dispersion terms of the potential model is proposed. Also, the effect of the inclusion of many-body effects such as polarizability, should also be investigated. - Highlights: ? Transport properties of liquid water are important in bio-simulations. ? Self-diffusion coefficient, shear and bulk viscosities calculations from NVE molecular dynamics simulations. ? Their comparison with experimental data provides information on intermolecular forces, and serve to develop water models

  10. Foundations of compositional models: structural properties.

    Czech Academy of Sciences Publication Activity Database

    Jiroušek, Radim; Kratochvíl, Václav

    2015-01-01

    Ro?. 44, ?. 1 (2015), s. 2-25. ISSN 0308-1079 R&D Projects: GA ?R GA13-20012S Grant ostatní: GA ?R(CZ) GAP403/12/2175 Institutional support: RVO:67985556 Keywords : multidimensional distribution * conditional independence * composition * semigraphoid properties * running intersection property Subject RIV: BA - General Mathematics Impact factor: 0.786, year: 2013 http://library.utia.cas.cz/separaty/2015/MTR/jirousek-0442412.pdf

  11. Relationship between Magnetic Domain Structures and Shear Stress in Magnetic Minerals of Geological Materials

    Science.gov (United States)

    Yagyu, E.; Kanamaru, T.; Takemura, T.

    2014-12-01

    The magnetic properties of rocks are affected by geomagnetic fields, heat and shearing stresses after formation. The shear stress associated with tectonic stress, for example, from a fault, can cause magnetic domain­-wall displacement. The wall displacement is thought to reflect the magnetic domain structure. Therefore, the hysteresis of strain, which rocks are subjected to in fault movements, can be used to estimate the structural disturbances of the magnetic domain. Previous studies have shown that the stress effect on magnetic domains can be observed by using industrial and synthetic materials, such as Si-Fe alloys (Chikazumi & Suzuki, 1995). However, few studies have used natural geological materials to study the effect of stress on magnetic domains. This study's objective is to verify the shear stress history of rocks by observing the magnetic domain structures via the Bitter method and magnetic force microscopy (MFM). Here, the Bitter method is the powder pattern method, whereby a colloidal suspension of the magnetic powder is prepared from magnetic materials, and the patterns of the domain wall produced by ferromagnetic particles are observed under a microscope. On observing the domain structures of industrial and synthetic materials, the remnant stress on the surface layer is removed after mechanical polishing (Hoffmann et al., 1987) because the remnant stress influences the domain structures. There are several technical problems during the observation of rocks compared with those during observation of industrial and synthetic materials. Electrolytical polishing does not work because the electrical conductivity is very low (e.g., Hoffmann et al., 1987). In previous studies of the observation of magnetic domains of rock minerals, the surface strain layer was removed by polishing with colloidal silica (Ozdemir, 1995,etc). In this study, we will attempt to conduct a verification experiment and observations of the magnetic domain structures in natural minerals of rocks, and would like to discuss the relationship between the shear stress and magnetic domain structures. Here, the polishing method was according to Hoffmann et al. (1987), and the magnetic domain was observed by the Bitter method and MFM. As a result, we can observe the magnetic domain walls, and each domain wall has a spacing of 3-5 ?m.

  12. Structure of vitreous body and its relationship with liquefaction

    Directory of Open Access Journals (Sweden)

    Makoto Kodama

    2013-07-01

    Full Text Available The aim of the study is to clarify the vitreous body structure and liquefaction phenomena. It was found that when melting a frozen rabbit vitreous body, the gel-sol transition phenomenon occurs and the gel structure is broken. This is almost like the liquefaction of the vitreous body in vivo. We try to clarify the liquefaction phenomenon by using this animal model. The native vitreous body has three dimensional meshwork structures. After liquefaction, it is changed into two parts, namely fiber aggregates and soluble amorphous aggregates. The surface of native vitreous body meshwork is mucopolysacharide, but that of fiber aggregates after liquefaction is changed into connective tissue, which means the conformational change of vitreous body in liquefaction. The soluble proteins after liquefaction were analyzed and identified as crystallin family. It is suggested that the liquefaction is induced by detachment of non-collagenous protein beads containing crystallins, resulting in the collapse of the three dimensional structure to release watery liquid trapped within. And the new gel-sol transition model of vitreous bod is proposed.

  13. Structure-efficiency relationship of [1,2,4]triazol-3-ylamines as novel nicotinamide isosteres that inhibit tankyrases.

    Science.gov (United States)

    Shultz, Michael D; Majumdar, Dyuti; Chin, Donovan N; Fortin, Pascal D; Feng, Yun; Gould, Ty; Kirby, Christina A; Stams, Travis; Waters, Nigel J; Shao, Wenlin

    2013-09-12

    Tankyrases 1 and 2 are members of the poly(ADP-ribose) polymerase (PARP) family of enzymes that modulate Wnt pathway signaling. While amide- and lactam-based nicotinamide mimetics that inhibit tankyrase activity, such as XAV939, are well-known, herein we report the discovery and evaluation of a novel nicotinamide isostere that demonstrates selectivity over other PARP family members. We demonstrate the utilization of lipophilic efficiency-based structure-efficiency relationships (SER) to rapidly drive the evaluation of this series. These efforts led to a series of selective, cell-active compounds with solubility, physicochemical, and in vitro properties suitable for further optimization. PMID:23879431

  14. Spiders in Motion: Demonstrating Adaptation, Structure-Function Relationships, and Trade-Offs in Invertebrates

    Science.gov (United States)

    Bowlin, Melissa S.; McLeer, Dorothy F.; Danielson-Francois, Anne M.

    2014-01-01

    Evolutionary history and structural considerations constrain all aspects of animal physiology. Constraints on invertebrate locomotion are especially straightforward for students to observe and understand. In this exercise, students use spiders to investigate the concepts of adaptation, structure-function relationships, and trade-offs. Students…

  15. Examining Relationships among Enabling School Structures, Academic Optimism and Organizational Citizenship Behaviors

    Science.gov (United States)

    Messick, Penelope Pope

    2012-01-01

    This study examined the relationships among enabling school structures, academic optimism, and organizational citizenship behaviors. Additionally, it sought to determine if academic optimism served as a mediator between enabling school structures and organizational citizenship behaviors. Three existing survey instruments, previously tested for…

  16. The Relationship between Organizational Structure and Organizational Justice

    OpenAIRE

    Amir Babak Marjani; Fateme Tohidy Ardahaey

    2012-01-01

    Organizational justice in this rapidly-developing work-life may become an increasingly important issue to both managers and employees. This article aims to study the effective organizational justice model for Iranian public organizations. It initially identifies antecedents and consequences of organizational justice. Then, it examines the effect of organizational justice on organizational commitment, trust, OCB, turnover, and job satisfaction as well as the impact of organizational structure ...

  17. Crystal structures, phase relationships, and magnetic phase transitions of R5M4 compounds (R = rare earths, M = Si, Ge)

    International Nuclear Information System (INIS)

    Our recent studies of the crystal structures, phase transitions, and magnetic properties of intermetallic compounds R5M4 (R = rare earths; M = Si, Ge) are reviewed briefly. First, crystal structures, phase relationships, and magnetic properties of several 5:4 compounds, including Nd5Si4?xGex, Pr5Si4?xGex, Gd5?xLaxGe4, La5Si4, and Gd5Sn4, are presented. In particular, the canted spin structures as well as the magnetic phase transitions in Pr5Si2Ge2 and Pr5Ge4 investigated by neutron powder diffractions and small-angle neutron scattering are reviewed. Second, the crystal structures and magnetic properties of the most studied compounds Gd5(Si,Ge)4 are summarized. The focus is on the parent compound Gd5Ge4, which is an amazing material exhibiting magnetic anisotropy, angular dependent spin-flop transition, metastable magnetic response, Griffiths-like phase, thermal effect under pulsed fields, antiferromagnetic and ferromagnetic resonances, pronounced effects of impurities, and high-field induced magnetic transitions. (topical review - magnetism, magnetic materials, and interdisciplinary research)

  18. Structure, reactivity, and biological properties of hidantoines

    International Nuclear Information System (INIS)

    Hydantoin (imidazolidine-2,4-dione) is a 2,4-diketotetrahydroimidazole discovered by Baeyer in 1861. Thiohydantoins and derivatives were prepared, having chemical properties similar to the corresponding carbonyl compounds. Some biological activities (antimicrobial, anticonvulsant, schistosomicidal) are attributed to the chemical reactivity and consequent affinity of hydantoinic rings towards biomacromolecules. Therefore, knowledge about the chemistry of hydantoins has increased enormously. In this review, we present important aspects such as reactivity of hydantoins, acidity of hydantoins, spectroscopy and crystallographic properties, and biological activities of hydantoin and its derivatives. (author)

  19. Structure-composition-activity relationships in transition-metal oxide and oxyhydroxide oxygen-evolution electrocatalysts

    Science.gov (United States)

    Trotochaud, Lena

    Solar water-splitting is a potentially transformative renewable energy technology. Slow kinetics of the oxygen evolution reaction (OER) limit the efficiency of solar-watersplitting devices, thus constituting a hurdle to widespread implementation of this technology. Catalysts must be stable under highly oxidizing conditions in aqueous electrolyte and minimally absorb light. A grand goal of OER catalysis research is the design of new materials with higher efficiencies enabled by comprehensive understanding of the fundamental chemistry behind catalyst activity. However, little progress has been made towards this goal to date. This dissertation details work addressing major challenges in the field of OER catalysis. Chapter I introduces the current state-of-the-art and challenges in the field. Chapter II highlights work using ultra-thin films as a platform for fundamental study and comparison of catalyst activity. Key results of this work are (1) the identification of a Ni0.9Fe0.1OOH catalyst displaying the highest OER activity in base to date and (2) that in base, many transition-metal oxides transform to layered oxyhydroxide materials which are the active catalysts. The latter result is critical in the context of understanding structure-activity relationships in OER catalysts. Chapter III explores the optical properties of these catalysts, using in situ spectroelectrochemistry to quantify their optical absorption. A new figure-of-merit for catalyst performance is developed which considers both optical and kinetic losses due to the catalyst and describes how these factors together affect the efficiency of composite semiconductor/catalyst photoanodes. In Chapter IV, the fundamental structure-composition-activity relationships in Ni1--xFexOOH catalysts are systematically investigated. This work shows that nearly all previous studies of Ni-based catalysts were likely affected by the presence of Fe impurities, a realization which holds significant weight for future study of Ni-based catalyst materials. Chapter V discusses the synthesis of tin-titanium oxide nanoparticles with tunable lattice constants. These materials could be used to make high-surface-area supports for thin layers of OER catalysts, which is important for maximizing catalyst surface area, minimizing the use of precious-metal catalysts, and optimizing 3D structure for enhanced mass/bubble transport. Finally, Chapter VI summarizes this work and outlines directions for future research.

  20. Structure-antioxidant relationships of sulfated galactomannan from guar gum.

    Science.gov (United States)

    Wang, Xiaofang; Wang, Junlong; Zhang, Ji; Zhao, Baotang; Yao, Jian; Wang, Yunpu

    2010-01-01

    Sulfated polysaccharides exerted potential biological property which was relative to degree of sulfation (DS), M(w), substitution position and chain conformation. In the present study, commercial guar gum was purified and its sulfated derivates with different DS and M(w) were synthesized. FT-IR and 13C NMR analysis indicated that C-6 substitution was predominant in sulfated samples compared with other positions. In the sulfation reaction, a sharp decrease in M(w) was observed. The d(f) values from 1.92 to 2.85 indicated that the -SO3H groups led to the relatively expanded conformation of sulfated polysaccharides. Antioxidant assays showed that sulfated polysaccharides had better antioxidant activities. The data obtained in in vitro models indicated that high DS and low M(w) showed the best antioxidant capacities. PMID:19836415

  1. Electronic Structure of some A3 Adenosine-Receptor Antagonist——A Structure Activity Relationship

    Directory of Open Access Journals (Sweden)

    M. F Shibl

    2011-06-01

    Full Text Available DFT quantum chemical computations have been carried out at the B3LYP/6-31G (d level. Full geometry optimization has been performed and equilibrium geometries for a new series of phenyl thiazoles have been located. Ground state electronic properties, charge density distributions, dipole moments and its components have been calculated and reported. Effect of substituents on the geometry and on the polarization of the studied series of compounds are analyzed and discussed. Some structural features have been pinpointed to underline the affinity and selectivity of the studied compounds as adenosine A3-receptor antagonists. Results of the present work indicate that activity towards A3 receptor sites is directly correlated with both of the polarity and the co-planarity of the thiazole.

  2. Structure-activity relationships of strychnine analogues at glycine receptors

    DEFF Research Database (Denmark)

    Mohsen, A.M.Y.; Heller, Eberhard

    2014-01-01

    Nine strychnine derivatives including neostrychnine, strychnidine, isostrychnine, 21,22-dihydro-21-hydroxy-22-oxo-strychnine, and several hydrogenated analogs were synthesized, and their antagonistic activities at human ?1 and ?1? glycine receptors were evaluated. Isostrychnine has shown the best pharmacological profile exhibiting an IC50 value of 1.6??M at ?1 glycine receptors and 3.7-fold preference towards the ?1 subtype. SAR Analysis indicates that the lactam moiety and the C(21)[DOUBLE BOND]C(22) bond in strychnine are essential structural features for its high antagonistic potency at glycine receptors

  3. Quantitative Structure – Antioxidant Activity Relationships of Flavonoid Compounds

    Directory of Open Access Journals (Sweden)

    Károly Héberger

    2004-12-01

    Full Text Available A quantitative structure ??? ?? antioxidant activity relationship (QSAR study of 36 flavonoids was performed using the partial least squares projection of latent structures (PLS method. The chemical structures of the flavonoids have been characterized by constitutional descriptors, two-dimensional topological and connectivity indices. Our PLS model gave a proper description and a suitable prediction of the antioxidant activities of a diverse set of flavonoids having clustering tendency.

  4. Synthesis and Structure-Activity Relationships of Second-Generation Hydroxamate Botulinum Neurotoxin A Protease Inhibitors

    OpenAIRE

    ?apková, Kate?ina; Yoneda, Yoshiyuki; Dickerson, Tobin J.; Janda, Kim D

    2007-01-01

    Botulinum neurotoxins are the most toxic proteins currently known. Based on a recently identified potent lead structure, 2,4-dichlorocinnamic acid hydroxamate, herein we report on the structure-activity relationship of a series of hydroxamate BoNT/A inhibitors. Among them, 2-bromo-4-chlorocinnamic acid hydroxamate, 2-methyl-4-chlorocinnamic acid hydroxamate and 2-trifluoromethyl-4-chlorocinnamic acid hydroxamate, displayed comparable inhibitory activity to that of the lead structure.

  5. Water-mediated protein-DNA interactions: the relationship of thermodynamics to structural detail.

    OpenAIRE

    Morton, C. J.; Ladbury, J. E.

    1996-01-01

    The elucidation of a relationship between the thermodynamic parameters and the structural changes accompanying biomolecular interactions could lead to predictive algorithms. For example, based on some knowledge of the structure of a target molecule the affinities of ligands could be determined with obvious implications for the pharmaceutical industry. In attempting to relate the thermodynamic and structural changes on formation of a protein-DNA complex, the correlation between change in heat ...

  6. Investigating The Relationship Between Flourishing And Self-Compassion: A Structural Equation Modeling Approach

    OpenAIRE

    Seydi Ahmet Satici; Recep Uysal; Ahmet Akin

    2013-01-01

    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 analysi...

  7. Okun's Law. Does the Austrian unemployment-GDP relationship exhibit structural breaks?

    OpenAIRE

    Sögner, Leopold

    2000-01-01

    Okun's Law postulates an inverse relationship between movements of the unemployment rate and the real gross domestic product (GDP). Empirical estimates for US data indicate that a two to three percent GDP growth rate above the natural or average GDP growth rate causes unemployment to decrease by one percentage point and vice versa. In this investigation we check whether this postulated relationship exhibits structural breaks by means of Markov-Chain Monte Carlo methods. We estimate a regressi...

  8. Structure-activity relationships of polybiguanides with activity against human immunodeficiency virus type 1

    OpenAIRE

    Passic, Shendra R.; Ferguson, Mary Lee; Catalone, Bradley J.; Kish-Catalone, Tina; Kholodovych, Vladyslav; Zhu, Wei; Welsh, William; Rando, Robert; Howett, Mary K.; Wigdahl, Brian; Labib, Mohamed; Fred C. Krebs

    2010-01-01

    Previous investigations showing that polydisperse biguanide (PDBG) molecules have activity against human immunodeficiency virus type 1 (HIV-1) also suggested a relationship between PDBG biologic activity and the lengths of hydrocarbon linkers surrounding the positively charged biguanide unit. To better define structure-activity relationships, PDBG molecules with select linker lengths were evaluated for cytotoxicity, anti-HIV-1 activity, and in vivo toxicity. Results of the in vitro experiment...

  9. Body mass index, perceived health, and happiness: their determinants and structural relationships

    OpenAIRE

    Cornelisse-vermaat, J. R.; Antonides, G.; Ophem, J. A. C.; Maassen Den Brink, H.

    2006-01-01

    The structural relationships between body mass index, perceived health and happiness have been studied in a survey of 700 native Dutch citizens. We found an indirect effect of body mass index on happiness, via perceived health. Age had an inverted U-shaped relationship with body mass index, and both education and smoking had a negative effect on body mass index. Being married, doing paid work, owning a house, and doing sports had positive effects on perceived health, suggesting that living a ...

  10. The relations of organization structure and customer relationship management in Ansar Bank of Urmia

    OpenAIRE

    Fariba Azizzadeh; Hamidreza Bahrami; Rasool Sarihi Sfestani

    2014-01-01

    This study attempts to examin the relationship between dimensions of organizational structure with customer relationship management in Ansar Bank of Urmia. Data was collected in 2012. A questionnaire as an instrument and Likert mode was used. Cronbach`s alpha was used to determine the reliability of questionnaire. The reliability of 0.887 was calculated. The Study sample includes all staff of Ansar Bank in Urmia that is 100 persons. After evaluation of validity and reliability of questions, d...

  11. Structure-activity relationship (SAR) modelling of mosquito larvicides.

    Science.gov (United States)

    Devillers, J; Doucet-Panaye, A; Doucet, J P

    2015-04-01

    An attempt was made to derive structure-activity models allowing the prediction of the larvicidal activity of structurally diverse chemicals against mosquitoes. A database of 188 chemicals with their activity on Aedes aegypti larvae was constituted from analysis of original publications. The activity values were expressed in log 1/IC50 (concentration required to produce 50% inhibition of larval development, mmol). All the chemicals were encoded by means of CODESSA and autocorrelation descriptors. Partial least squares analysis, classification and regression tree, random forest and boosting regression tree analyses, Kohonen self-organizing maps, linear artificial neural networks, three-layer perceptrons, radial basis function artificial neural networks and support vector machines with linear, polynomial, radial basis function and sigmoid kernels were tested as statistical tools. Because quantitative models did not give good results, a two-class model was designed. The three-layer perceptron significantly outperformed the other statistical approaches regardless of the threshold value used to split the data into active and inactive compounds. The most interesting configuration included eight autocorrelation descriptors as input neurons and four neurons in the hidden layer. This led to more than 96% of good predictions on both the training set and external test set of 88 and 100 chemicals, respectively. From the overall simulation results, new candidate molecules were proposed which will be shortly synthesized and tested. PMID:25864415

  12. Structure and phytogeographic relationships of swamp forests of Southeast Brazil

    Scientific Electronic Library Online (English)

    Bruno Coutinho, Kurtz; Jorge Caruzo, Gomes; Fabio Rubio, Scarano.

    2013-12-01

    Full Text Available Swamp forests are associated with soils that are saturated or inundated because of a high water table. In Brazil, little is known about the plant ecology of such forests. In this paper, we aimed to describe the phytosociological structure of the tree layer of swamp forests in Restinga de Jurubatiba [...] National Park, in the northern part of the state of Rio de Janeiro, and to evaluate the floristic similarities between these forests and some other possibly related types of vegetation formations in Brazil. The sampling included 84 species, within 62 genera and 34 families. The Shannon diversity index was 3.42, and the Shannon evenness index was 0.77. The forests studied showed an oligarchic structure; Tapirira guianensis, Calophyllum brasiliense and Protium icicariba were the most important species. Oligarchy, or monodominance, and relatively low species richness are the norm in the swamp forests of southeastern Brazil and result from the strong selective character of the saturated/inundated soils. In comparison with local areas of restinga (coastal woodland), Atlantic Forest sensu stricto, other swamp forests and flooded riparian forests, the similarity was low (Jaccard similarity coefficient

  13. Atomic structure-colour relationship in natural diamonds

    International Nuclear Information System (INIS)

    Colour is a physical attribute that can be very difficult to characterise in diamond and consequently it receives regular attention from scientists working in the gem industry. In this work we compare natural brown (the most common colour) and colourless type IIa diamonds containing only trace quantities (< 1 at. ppm) of nitrogen. Numerous attempts have been made to trace the origin of brown tints in natural diamond, with the most likely culprits, i.e. dislocations and nitrogen impurities, ruled out through the application of various analytical techniques. Consequently more emphasis has recently been placed on the study of smaller defects in the diamond structure and their influence on colour. The focus of this research work is the analysis of vacancy defects having a size of the order of 1nm using aberration corrected scanning transmission electron microscopy (AC-STEM). The small electron probe size and depth of focus afforded by this technique allows such defect structures together with their position to be resolved far more readily than with conventional HR-TEM. Small-scale contrast variations are apparent in the lattice images of brown and not of colourless diamonds. These features have been compared to simulated phase contrast images of vacancy clusters in diamond. In addition, both experimental and simulated defocus series indicate that such features are not restricted to the surface of the specimen.

  14. Novel optical transmission property of metal-dielectric multilayered structure

    International Nuclear Information System (INIS)

    A kind of planar metal-dielectric multilayered plasmonic structure has been proposed and its optical properties have been studied. Numerical calculations show that both the electric resonance (surface-plasmon polariton resonance) and the magnetic resonance (localized magnetic-plasmon resonance) can enhance the optical transmission. Moreover, by modulating the dimensions of the proposed structure, a large resonance quality factor and a continuum resonance can be achieved. These controllable optical properties might be useful for various practical implementations.

  15. Ceramic and glass materials structure, properties and processing

    CERN Document Server

    Shackelford, James F

    2008-01-01

    Ceramics and Glasses: Structure, Properties and Processing covers a wide range of important ceramic and glass materials used in modern technology. The book provides essential information on the nature of key ceramic raw materials including their structure, properties, processing methods and applications in engineering and technology. Coverage extends to materials such as Alumina; Aluminates; Andalusite, Kyanite, and Sillimanite; Clays; Concrete and Cement; Lead Compounds; Mullite; Quartzes and Silicas; Refractory Oxides; Zirconia and more. Written by recognized leaders in the field of ceramic

  16. Structure and properties of Titanium for dental implants

    OpenAIRE

    Greger, M.; C?erny?, M.; Kander, L.; Kliber, J.

    2009-01-01

    This paper describes manufacture of nano-structural titanium, its structure and properties. Nano-titanium has higher specific strength properties than ordinary (coarse-grained) titanium. Nano-titanium was produced by the equal-channel angular pressing (ETAP) process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of nano-titanium varies aroun...

  17. Mechanical properties along interfaces of bonded structures in fusion reactors

    International Nuclear Information System (INIS)

    Proper assessment of the mechanical properties along interfaces of bonded structures currently used in many fusion reactor designs is essential to compare the different fabrication techniques. A Mechanical Properties Microprobe (MPM) was used to measure hardness and Young's modules along the interfaces of Be/Cu bonded structure. The MPM was able to distinguish different fabrication techniques by a direct measurement of the hardness, Young's modules, and H/E2 which reflects the ability of deformation of the interfacial region

  18. Structural properties of fluorozirconate-based glass ceramics doped with multivalent europium

    OpenAIRE

    Paßlick, C; Müller, O; Lützenkirchen-Hecht, D.; R. Frahm; Johnson, J.A.; Schweizer, S.

    2011-01-01

    The structure/property relationships of fluorochlorozirconate glass ceramics as a function of divalent and trivalent europium (Eu) co-doping and thermal processing have been investigated; the influence of doping ratio on the formation of barium chloride (BaCl2) nanocrystals therein was elucidated. X-ray absorption near-edge structure spectroscopy shows that the post-thermal annealing changes the Eu valence of the as-poured glass slightly, but during the melting process Eu3+ is more strongly r...

  19. Geometric and electronic structure of dysprosium thin films on tungsten surfaces Structural and magnetic properties

    CERN Document Server

    Moslemzadeh, N

    2001-01-01

    The rare earth thin films are frequently the focus of investigators due to their unusual structural and magnetic properties. Despite the potential interest of Dy/W systems to the surface/rare earth community, they have been little studied. This study is the first try of growing Dy on W(100) and W(112) and W(110) in which almost a complete set of information about film morphology and electronic structure of the surface and interface have been achieved. A set of different experiments have been done for this purpose including LEED, XPS, UPS (with synchrotron radiation) and STM. The growth modes of Dy on different W substrates (W(100), W(112) and W(110)) at RT and at elevated temperatures have been determined by XPS of Dy 3d sub 3 sub / sub 2 and W 4f intensities. Crystallographic ordering and the epitaxial relationship between adsorbate Dy and different W substrates have been studied with LEED and the effect of annealing temperature on the resultant superstructures was investigated. As a complementary study to t...

  20. Quantitative Structure activity relationship and risk analysis of some pesticides in the cattle milk

    Directory of Open Access Journals (Sweden)

    Faqir Muhammad*, Ijaz Javed, Masood Akhtar1, Zia-ur-Rahman, Mian Muhammad Awais1, Muhammad Kashif Saleemi2 and Muhammad Irfan Anwar3

    2012-10-01

    Full Text Available Milk of cattle was collected from various localities of Faisalabad, Pakistan. Pesticides concentration was determined by HPLC using solid phase microextraction. The residue analysis revealed that about 40% milk samples were contaminated with pesticides. The mean±SE levels (ppm of cyhalothrin, endosulfan, chlorpyrifos and cypermethrin were 0.38±0.02, 0.26±0.02, 0.072±0.01 and 0.085±0.02, respectively. Quantitative structure activity relationship (QSAR models were used to predict the residues of unknown pesticides in the milk of cattle using their known physicochemical properties such as molecular weight (MW, melting point (MP, and log octanol to water partition coefficient (Ko/w as well as the milk characteristics such as pH, % fat, and specific gravity (SG in this species. The analysis revealed good correlation coefficients (R2 = 0.91 for cattle QSAR model. The coefficient for Ko/w for the studied pesticides was higher in cattle milk. Risk analysis was conducted based upon the determined pesticide residues and their provisional tolerable daily intakes. The daily intake levels of pesticide residues including cyhalothrin, chlorpyrifos and cypermethrin in present study were 3, 11, 2.5 times higher, respectively in cattle milk. This intake of pesticide contaminated milk might pose health hazards to humans in this locality.

  1. Growth and structural properties of silicene at multilayer coverage.

    Science.gov (United States)

    Salomon, E; El Ajjouri, R; Le Lay, G; Angot, T

    2014-05-01

    At monolayer coverage, silicene on Ag(1?1?1) may present different structural phases depending on the growth conditions. At multilayer coverage, only one structural phase has been reported: the [Formula: see text] phase. However, no link between the structural arrangement of the monolayer and that of the multilayer has been addressed. In this paper, reporting experimental work based on low-energy electron diffraction and scanning tunneling microscopy, we focus on the structural aspects of a multilayer film of silicene. We demonstrate that it exhibits one structural arrangement, namely the [Formula: see text] form, but with different domain orientations resulting from the structural properties of the initial wetting monolayer. PMID:24728034

  2. Influence of surface structure on thermoprotection properties of intumescent systems

    Science.gov (United States)

    Reshetnikov, Igor S.; Yablokova, Marina Yu.; Khalturinskij, Nikolay A.

    1997-06-01

    Intumescent fire retardant coatings have found great application due to high thermoprotection properties, which reduce heat flow on the polymer surface. However there were no attempts to study the influence of surface structure on foamed char formation processes. In this work we present the experimental investigation of thermoprotection properties of CFR with a PTFE modified surface.

  3. Structure-function relationships of the vitamin D hormone receptor

    International Nuclear Information System (INIS)

    Avian intestinal cytosoluble receptors for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were subjected to limited trypsin digestion, endogenous proteolytic action, as well as carboxypeptidase treatment, and the physical and functional properties of the resulting discrete polypeptide fragments were identified and contrasted with the native 1,25(OH)2D3 receptor. Resultant fragments were followed by tracing either radioactive 1,25(OH)2D3 or by probing with anti-receptor monoclonal antibodies. Two differentially trypsin-sensitive effects on the 1,25(OH)2D3 receptor were noted when fragments were detected by their ability to bind 1,25(OH)2[3H]D3. Two hormone-bound fragments of 40 and 30 kDa were formed; neither bound to DNA-cellulose nor anti-receptor monoclonal antibodies. Immunoblot technology was used to show the disappearance of the 60 kDA receptor with increasing trypsin concentrations, paralleling the appearance of an immunoreactive 20 kDA fragment. The 20 kDA fragment did not bind hormone but was capable of interacting with DNA-cellulose in a fashion identical to that of the 60 kDA receptor. In contrast to the exogeneous effect of trypsin, incubation of chick intestinal cytosol resulted in the time-dependent formation of an endogenous protease-derived fragment of 45 kDa

  4. Relationship between pyrolysis reactivity and aromatic structure of coal

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, H.; Isoda, T.; Kusakabe, K.; Morooka, S. [Kyushu University, Fukuoka (Japan). Dept. of Materials Physics and Chemistry

    2000-06-01

    Illinois No. 6 coal was depolymerized by treatment with trifluoromethanesulfonic acid in methylcyclopentane at 120{degree}C. The yield of tetrahydrofuran (THF) extract was increased to 89 wt%. This increase was explained by the cleavage of bridges between aromatic units. The extract (TS{sub d} fraction) was further hydrogenated using a Ru/carbon catalyst in a mixed solvent of THF and acetic acid at 120{degree}C for 12-72 h under a hydrogen pressure of 10 MPa. Phenolic resin and polystyrene samples were used as references and were also hydrogenated over Ru/Al{sub 2}O{sub 3} catalyst under the same conditions. After hydrogenation for 72 h, the aromaticity of the hydrogenated TS{sub d} fraction (H-TS{sub d} fraction), f{sub a}. decreased to 0.33 from the original value, 0.6. The pyrolysis reactivity of the treated coals was evaluated using a Curie-point pyrolyser (CPP) at 500-764{degree}C in a stream of helium. The reactivity of the TS{sub d} fraction was greatly enhanced as a result of the hydrogenation, and 96 wt% of the H-TS{sub d} fraction was converted to volatiles during the pyrolysis at 764{degree}C. A good correlation between the aromaticity and the yield of volatiles was found for both the treated coals and phenolic resins, but not for the polystyrenes. This suggests that pyrolysis reactivity was related to the aromatic structures of the main chains, and that those structures were changed by the hydrogenation. 27 refs., 14 figs., 1 tab.

  5. Electronic and Thermal Properties of Graphene and Carbon Structures

    Science.gov (United States)

    Anthony, Gilmore; Khatun, Mahfuza

    2011-10-01

    We will present the general properties of carbon structures. The research involves the study of carbon structures: Graphene, Graphene nanoribbons (GNRs), and Carbon Nanotubes (CNTs). A review of electrical and thermal conduction phenomena of the structures will be discussed. Particularly carbon nanoribbons and CNTs have many interesting physical properties, and have the potential for device applications. Our research interests include the study of electronic structures, electrical and thermal transport properties of the carbon structures. Results are produced analytically as well as by simulation. The numerical simulations are conducted using various tools such as Visual Molecular Dynamics (VMD), Large Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), NanoHub at Purdue University and the Beowulf Cluster at Ball State University.

  6. Plasticization effect of triacetin on structure and properties of starch ester film.

    Science.gov (United States)

    Zhu, Jie; Li, Xiaoxi; Huang, Chen; Chen, Ling; Li, Lin

    2013-05-15

    The aim of this work was to evaluate the plasticizing effect of triacetin on the structure and properties of starch ester film and further establish the structure-property relationships. The presence of triacetin resulted in multiple structure changes of the film. The mobility of macromolecular chain was increased to form scattered crystallite during the film formation process. The amorphous region was enlarged to contain more triacetin squeezed from crystalline region. The plasticization of triacetin and restriction of crystallite oppositely influenced the mobility of macromolecular chains in different regions. The thermal stability of triacetin changed along with its fluctuant interaction with macromolecules. Comparatively, the enhanced ether bond and the restriction from crystalline regions on the mobility of the amorphous chain consequently improved the thermal stability of the film matrix. The interaction between triacetin and starch ester was essential to film forming but unexpectedly lowered the triacetin stability. PMID:23544645

  7. Using crystallographic water properties for the analysis and prediction of lectin-carbohydrate complex structures.

    Science.gov (United States)

    Modenutti, C; Gauto, D; Radusky, L; Blanco, J; Turjanski, A; Hajos, S; Marti, Ma

    2015-02-01

    Understanding protein-ligand interactions is a fundamental question in basic biochemistry, and the role played by the solvent along this process is not yet fully understood. This fact is particularly relevant in lectins, proteins that mediate a large variety of biological processes through the recognition of specific carbohydrates. In the present work, we have thoroughly analyzed a nonredundant and well-curated set of lectin structures looking for a potential relationship between the structural water properties in the apo-structures and the corresponding protein-ligand complex structures. Our results show that solvent structure adjacent to the binding sites mimics the ligand oxygen structural framework in the resulting protein-ligand complex, allowing us to develop a predictive method using a Naive Bayes classifier. We also show how these properties can be used to improve docking predictions of lectin-carbohydrate complex structures in terms of both accuracy and precision, thus developing a solid strategy for the rational design of glycomimetic drugs. Overall our results not only contribute to the understanding of protein-ligand complexes, but also underscore the role of the water solvent in the ligand recognition process. Finally, we discuss our findings in the context of lectin specificity and ligand recognition properties. PMID:25267604

  8. THE RELATIONSHIPS BETWEEN BIOCHEMICAL ACTIVITY CHARACTERICTIES AND SOIL PROPERTIES OF HAZELNUT GROWN SOILS

    Directory of Open Access Journals (Sweden)

    Ayten KARACA

    1998-03-01

    Full Text Available In this research, enzyme activities of soil cultivated for hazelnut in Terme and Ünye townships were determined and the relationships between the activities and some soil properties, trace elements and heavy metals were evaluated. Correlation and regression analysis showed that there was significant positive correlation between urease activity and organic carbon, nitrogen and extractable Cu; strong positive correlation between acid phosphates activity and organic matter, organic carbon and nitrogen; but negative correlation between the activities and extractable Mn content. Additionally, positive correlation was found between alkaline phosphatase activity and pH, available P, extractable Cu, Zn and Pb contents. With the exception of C/N ratio and extractable Cd content, no significant correlation was observed between ß- glikosidase activity and soil properties.

  9. Relationship between electric properties and width of cracks of Inconel alloy

    International Nuclear Information System (INIS)

    In Service Inspection (ISI) of Steam Generator tubes in Pressurized Water React, ECT technique which is one of most common Non Destructive Inspection (NDI) techniques, is routinely used. To evaluate the detectability of cracks by Eddy Current Testing (ECT), it is very important to clarify the change of electric properties of the material due to existence of the cracks. In this study, they investigated the relationship between the change of electric properties, especially electric resistivity, and the width of cracks of test pieces of Inconel alloy by both experiments and numerical analysis. Artificial Stress Corrosion Cracks (SCC) and a fatigue crack were used in the experiments. Measurements by ECT were carried out for those cracks with various widths which were controlled by a three-point loading method. The coil impedance change did not increase significantly, as the width of the cracks increased, From these results, they could conclude that ECT might detect very thin cracks with the width less than 1 microm

  10. The relationship between soil physical properties and alpine plant diversity on Qinghai-Tibet Plateau

    Directory of Open Access Journals (Sweden)

    Lin Tang

    2015-04-01

    Full Text Available Through a large-scale research, we examined the heterogeneity of soil properties and plant diversity, as well as their relationships across alpine grassland types on Qinghai-Tibet Plateau. The soil pH and EC value increased with the constant deepening of the soil in all the three alpine grassland types which in order of absolute value in every soil layer were alpine desert steppe, alpine steppe and alpine meadow. Among the three grassland types, the alpine meadow possessed the highest SM but the lowest SBD. For plant diversity, alpine meadow was the highest, alpine desert steppe ranked the second and alpine steppe was the last. SM and SBD were the highest influential soil physical properties to species richness, but with opposite effects.

  11. Relationship between ultrasonic characteristics and mechanical properties of tempered martensitic stainless steel

    Science.gov (United States)

    Hsu, Cheng-Hsun; Teng, Hwei-Yuan; Chen, Yeong-Jern

    2004-10-01

    This research studied the relationship between the ultrasonic characteristics and the mechanical properties of tempered CA-15 martensitic stainless steel (MSS). The results show that, for as-quenched specimens, a chromium carbide film at the martensitic boundary of the as-cast specimen will disappear causing a change in the mechanical properties (e.g., the tensile strength is decreased or the hardness and the toughness are increased). For the tempered MSS, the correlation of the ultrasonic velocity and the tensile strength, hardness, and toughness is not obvious. However, there is a highly positive correlation with the elastic modulus (E) of the material. For the ultrasonic attenuation evaluation, the attenuation coefficient (?) has a positive correlation with the tensile strength and the hardness, while there is a negative correlation with the toughness and the elongation. Also, a higher-frequency probe would cause the better sensitivity, but the data are relatively dispersed.

  12. On Structure and Properties of Amorphous Materials

    OpenAIRE

    Zbigniew H. Stachurski

    2011-01-01

    Mechanical, optical, magnetic and electronic properties of amorphous materials hold great promise towards current and emergent technologies. We distinguish at least four categories of amorphous (glassy) materials: (i) metallic; (ii) thin films; (iii) organic and inorganic thermoplastics; and (iv) amorphous permanent networks. Some fundamental questions about the atomic arrangements remain unresolved. This paper focuses on the models of atomic arrangements in amorphous materials. The earliest ...

  13. Disjunction Property and Complexity of Structural Logics.

    Czech Academy of Sciences Publication Activity Database

    Hor?ík, Rostislav

    Lisbon : Instituto Superior Técnico - Departemanto de Matemática, 2010 - (Béziau, J.; Caleiro, C.; Costa-Leite, A.; Ramos, J.). s. 52-52 ISBN 978-972-99289-2-5. [UniLog 2010. World Congress and School on Universal Logic /3./. 18.04.2010-25.04.2010, Monte Estoril] Institutional research plan: CEZ:AV0Z10300504 Keywords : disjunction property * substructural logic * computational complexity Subject RIV: BA - General Mathematics

  14. The properties and structure of the carburizers

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2010-01-01

    Full Text Available The results of examinations of the carburizers for foundry industry were presented in the article. The commonly used carburizers were selected for the experiments (anthracite, natural and synthetic graphite, petroleum coke of various grades, cupola coke and charcoal as well. The experiments consist of bulk and standard density, screen analysis (on the basis of it the equivalent diameter was calculated and the microstructure of the carburizers measurements. The chemical composition and basic properties of carburizers were described too.

  15. The influence of chemical composition on structure and mechanical properties of austenitic Cr-Ni steels

    Directory of Open Access Journals (Sweden)

    A. Kurc-Lisiecka

    2013-12-01

    Full Text Available Purpose: The aim of the paper is to investigated the influence of the chemical composition on the structure and mechanical properties of austenitic Cr-Ni steels. Special attention was put on the effect of solution heat treatment on mechanical properties of examined steels. Design/methodology/approach: The examinations of static tensile tests were conducted on ZWICK 100N5A. Hardness measurements were made by Vickers method. The X-ray analyzes were realized with the use of Dron 2.0 diffractometer equipped with the lamp of the cobalt anode. The metallographic observations were carried out on LEICA MEF 4A light microscope. Findings: Results shown that after solution heat treatment the values of strength properties (UTS, YS0.2 and hardness (HV of both investigated steels decrease and their elongation (EL increases. The X5CrNi18-8 steel in delivery state shown austenitic microstructure with twins and numerous non-metallic inclusions, while in steel X10CrNi18-8 revealed a austenitic microstructure with numerous slip bands in areas with deformation martensite ?’. The examined steels after solution heat treatment followed by water-cooling has the structure of austenite. Research limitations/implications: To investigate in more detail the influence of chemical composition on structure and mechanical properties the examinations of substructure by TEM should be conducted. Originality/value: The relationship between the solution heat treatment, structure and mechanical properties of investigated steels was specified.

  16. Magnetic and structural properties of thulium chromate

    International Nuclear Information System (INIS)

    Full text: The Cr5+ S = 1/2 sub-lattice of tetragonal TmCrO4 orders magnetically at TC = 18.75 K. Neutron diffraction at 2 K shows ferromagnetic Tm3+ and Cr5+ sub-lattices aligned parallel to the c-axis. According to 169Tm Moessbauer spectroscopy, the magnetic phase (at least that of the Tm3+ sub-lattice) grows at the expense of the paramagnetic phase as the temperature decreases below TC. A second structural phase (approximately 25%) is also observed over a wide temperature range. However, this is not supported by neutron diffraction which indicates a single tetragonal structure at 50K and a single orthorhombic structure at 20 K and 2 K. It is possible that Moessbauer spectroscopy is observing a local dynamic distortion. Attempts to interpret Moessbauer and inelastic neutron scattering data in terms of the rare earth site crystal field interaction will also be described. (authors)

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

    International Nuclear Information System (INIS)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shih-Jye [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Lin, Ken-Huang; Li, Jia-Yun [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Ju, Shin-Pon, E-mail: jushin-pon@mail.nsysu.edu.tw [Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2014-10-07

    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.

  19. Structure and functional relationships in human pur H.

    Science.gov (United States)

    Beardsley, G P; Rayl, E A; Gunn, K; Moroson, B A; Seow, H; Anderson, K S; Vergis, J; Fleming, K; Worland, S; Condon, B; Davies, J

    1998-01-01

    1. The human pur H (ATIC) gene encoding a bifunctional protein, hPurH, which carries the penultimate and final enzymatic activities of the purine nucleotide synthesis pathway, AICARFT & IMPCH, has been cloned and sequenced. The gene product, hPurH has been overexpressed in E. coli, purified to homogeneity and crystallized. 2. The human pur H gene lies on chromosome 2, between band q34 and q35. There is at least one intron of 278 bp near the 5' end. 3. Truncation mutant studies demonstrate two non-overlapping functional domains in the protein arranged as indicated in Figure 5. The existence of a linker or interaction region between the catalytic domains remains to be established. 4. Cleland-type kinetic inhibition experiments indicate that the AICARFT reaction is of the ordered, sequential type with the reduced folate cofactor binding first. 5. The reaction has a broad pH optimum in the alkaline range, with a maximum at about pH 8.2. 6. Preliminary transient phase kinetic studies show the presence of a "burst" indicating that a late step in the reaction sequence is rate limiting. 7. A PurH crystal structure is that of a dimer, with a putative single binding site for the reduced folate cofactor formed using elements from each of the monomer subunits. Probable binding sites for AICAR and FAICAR can be identified on each monomer. 8. Equilibrium sedimentation studies show hPurH apoprotein to be a monomer:dimer equilibrium mixture with a kD of 0.55 uM. 9. The crystal structure has permitted identification of a number of candidate amino acid residues likely to be involved in catalysis and/or substrate binding. Among these, we have thus far completed studies on two, Lysine 265 and Histidine 266. These appear to be critically involved in the AICARFT reaction, although whether their role(s) are in catalysis or binding remains to be determined. PMID:9598063

  20. Composition, structure and properties of tantalum boride nanostructured films

    International Nuclear Information System (INIS)

    The structure, as well as the phase and elemental compositions, of tantalum diboride-based nano-structured films deposited by radiofrequency magnetron sputtering under various conditions are studied by X-ray diffraction, electron microscopy, and secondary ion mass spectrometry. The physicomechanical properties of the films (hardness, as well as elastic and plastic properties) are determined. The maximum hardness and elastic modulus of the synthesized films are 42 and 240 GPa, respectively. The grain size is found to influence the physicomechanical and electrical properties of the films

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

    International Nuclear Information System (INIS)

    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

  2. Quantitative Structure-Activity Relationships Predicting the Antioxidant Potency of 17?-Estradiol-Related Polycyclic Phenols to Inhibit Lipid Peroxidation

    Directory of Open Access Journals (Sweden)

    Katalin Prokai-Tatrai

    2013-01-01

    Full Text Available The antioxidant potency of 17?-estradiol and related polycyclic phenols has been well established. This property is an important component of the complex events by which these types of agents are capable to protect neurons against the detrimental consequences of oxidative stress. In order to relate their molecular structure and properties with their capacity to inhibit lipid peroxidation, a marker of oxidative stress, quantitative structure-activity relationship (QSAR studies were conducted. The inhibition of Fe3+-induced lipid peroxidation in rat brain homogenate, measured through an assay detecting thiobarbituric acid reactive substances for about seventy compounds were correlated with various molecular descriptors. We found that lipophilicity (modeled by the logarithm of the n-octanol/water partition coefficient, logP was the property that influenced most profoundly the potency of these compounds to inhibit lipid peroxidation in the biological medium studied. Additionally, the important contribution of the bond dissociation enthalpy of the phenolic O-H group, a shape index, the solvent-accessible surface area and the energy required to remove an electron from the highest occupied molecular orbital were also confirmed. Several QSAR equations were validated as potentially useful exploratory tools for identifying or designing novel phenolic antioxidants incorporating the structural backbone of 17?-estradiol to assist therapy development against oxidative stress-associated neurodegeneration.

  3. Atomic force microscopy study of the structure function relationships of the biofilm-forming bacterium Streptococcus mutans

    Science.gov (United States)

    Cross, Sarah E.; Kreth, Jens; Zhu, Lin; Qi, Fengxia; Pelling, Andrew E.; Shi, Wenyuan; Gimzewski, James K.

    2006-02-01

    Atomic force microscopy (AFM) has garnered much interest in recent years for its ability to probe the structure, function and cellular nanomechanics inherent to specific biological cells. In particular, we have used AFM to probe the important structure-function relationships of the bacterium Streptococcus mutans. S. mutans is the primary aetiological agent in human dental caries (tooth decay), and is of medical importance due to the virulence properties of these cells in biofilm initiation and formation, leading to increased tolerance to antibiotics. We have used AFM to characterize the unique surface structures of distinct mutants of S. mutans. These mutations are located in specific genes that encode surface proteins, thus using AFM we have resolved characteristic surface features for mutant strains compared to the wild type. Ultimately, our characterization of surface morphology has shown distinct differences in the local properties displayed by various S. mutans strains on the nanoscale, which is imperative for understanding the collective properties of these cells in biofilm formation.

  4. Structure–function relationship of ?-lactoglobulin in the presence of sodium dodecylbenzenesulfonate

    International Nuclear Information System (INIS)

    Highlights: ? Stability parameters and retinol binding property of ?-lg in the presence of SDBS have been determined at various pH. ? Higher denaturating effect of SDBS at acidic pH can be due to positive charge density of ?-lg at this pH. ? SDBS enhances the retinol binding affinity of ?-lg in all of its concentration range. ? The ?-lg/retinol binding is pH-dependent. - Abstract: Bovine ?-lactoglobulin (?-lg) present in milks has been found “in vivo” in complexes with lipids such as butyric and oleic acids. To elucidate the still unknown structure–function relationship in this protein, the structural changes of ?-lactoglobulin variant A (?-lg A) were investigated in the presence of sodium dodecylbenzenesulfonate (SDBS) as an anionic surfactant using spectrofluorimetry. Subsequently, the retinol binding was investigated by ?-lg in the presence of various amounts of this surfactant as its extrinsic functional binding fluorophore. The comparison of the results allowed for determining the binding of retinol by ?-lg in the presence of SDBS. The results of fluorescence studies showed a higher denaturating effect of SDBS at acidic pH that can be due to the positive charge density of ?-lg at this pH which was calculated using the Henderson–Hasselbalch equation and pKa values of its ionizable groups. For each transition curve, the conventional method of analysis which assumed a linear concentration dependence of the pre- and post-transitid post-transition base lines gave the most realistic values for ?GDo(H2O). The value of about 21.6 kJ · mol?1 was obtained for ?GDo(H2O) at various pH from transition curves. The results of retinol binding studies represented the substantial enhancement of retinol binding affinity of ?-lg in the presence of this surfactant at various pH levels. Moreover, the obtained results confirmed that the ?-lg/retinol binding was pH-dependent.

  5. [Perspective of predictive toxicity assessment of in vivo repeated dose toxicity using structural activity relationship].

    Science.gov (United States)

    Ono, Atsushi

    2010-01-01

    Tens of thousands of existing chemicals have been widely used for manufacture, agriculture, household and other purposes in worldwide. Only approximately 10% of chemicals have been assessed for human health hazard. The health hazard assessment of residual large number of chemicals for which little or no information of their toxicity is available is urgently needed for public health. However, the conduct of traditional toxicity tests which involves using animals for all of these chemicals would be economically impractical and ethically unacceptable. (Quantitative) Structure-Activity Relationships [(Q)SARs] are expected as method to have the potential to estimate hazards of chemicals from their structure, while reducing time, cost and animal testing currently needed. Therefore, our studies have been focused on evaluation of available (Q)SAR systems for estimating in vivo repeated toxicity on the liver. The results from our preliminary analysis showed the distribution for LogP of the chemicals which have potential to induce liver toxicity was bell-shape and indicating the possibility to estimate liver toxicity of chemicals from their physicochemical property. We have developed (Q)SAR models to in vivo liver toxicity using three commercially available systems (DEREK, ADMEWorks and MultiCASE) as well as combinatorial use of publically available chemoinformatic tools (CDK, MOSS and WEKA). Distinct data-sets of the 28-day repeated dose toxicity test of new and existing chemicals evaluated in Japan were used for model development and performance test. The results that concordances of commercial systems and public tools were almost same which below 70% may suggest currently attainable knowledge of in silico estimation of complex biological process, though it possible to obtain complementary and enhanced performance by combining predictions from different programs. In future, the combinatorial application of in silico and in vitro tests might provide more accurate information which support regulatory decisions. At the same time, an appropriate strategy to use (Q)SAR for of the efficiency and accuracy in chemical management is necessary. PMID:21381395

  6. Gill structure and relationships of the Triassic cycloid crustaceans.

    Science.gov (United States)

    Dzik, Jerzy

    2008-12-01

    Unusually well-preserved fossils of a Halicyne-like cycloid crustacean frequently occur in the early Late Triassic lacustrine clay bed at Krasiejów in Opole Silesia, southern Poland. Its gill-like structures form a horseshoe-shaped pair of units composed of numerous calcified blades with reverse U-shaped cross-section. Originally, these were parallel slits opening on the ventral surface of the carapace. Lobation of the posterior margin of the carapace, of unusually large mature size for the group, make the animal different from other members of Halicynidae, and the new name Opolanka decorosa gen. et sp. nov. is proposed for it. More completely preserved specimens of cycloids from Vosges, France, and Madagascar show that the slit openings were located above radially arranged coxae of the walking appendages and a reduced abdomen. The disposition and arrangement of the cycloid gills suggest at least close analogy, and possibly homology, with the "respiratory areas" of the Branchiura, serving mostly as ion-exchange organs. It is proposed that they originated, in connection with the body size increase and adaptation to fresh-water environment, as radially arranged infoldings of the respiratory areas cuticle, with strongly calcified rigid dorsal parts suspended from the carapace. At least three ecologically and anatomically distinct lineages were represented in the order Cyclida, which was probably initially confined to marine environments and gradually adapted to life in continental waters. New taxa Schraminidae fam. nov. (with Schramine gen. nov.) and Americlidae fam. nov. (with Americlus gen. nov.) are proposed. PMID:18690662

  7. Correlation of stability/rheology relationship with coal properties and chemical additives

    Energy Technology Data Exchange (ETDEWEB)

    Ohene, F.

    1989-01-01

    Coal-water slurry (CWS) is being considered as a near term replacement for oil in both industrial and utility applications. Selecting an economical, yet technically compatible feedstock for producing highly loaded CWS is important to the commercializatio