WorldWideScience

Sample records for structure properties relationships

  1. 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 relationship...

  2. Structure–property relationship of specialty elastomer–clay nanocomposites

    Indian Academy of Sciences (India)

    Anirban Ganguly; Madhuchhanda Maiti; Anil K Bhowmick

    2008-06-01

    The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray diffraction and physico-mechanical properties. Due to polarity match, hydrophilic unmodified montmorillonite clay showed enhanced properties in resulting fluoroelastomer nanocomposites, while hydrophobic organo-clay showed best results in SEBS nanocomposites.

  3. Electron beam crosslinked PVC : structure property relationships

    International Nuclear Information System (INIS)

    PVC is used extensively for its insulating properties for the manufacture of wires and cables and for other applications. Its gradual degradation, oxidation and even dehydro chlorination restricts use for long lasting period in installations such as high temperature zones, underground cables, communication systems, electro-nuclear facilities, etc. The technological properties and performance characteristics of PVC based insulation can be improved via crosslinking by high-energy electrons. PVC is however a polymer, which on irradiation predominantly undergoes degradation. To avoid degradation, it needs to be compounded with sensitizing agents or multifunctional monomers so that crosslinking is the predominant reaction. Radiation cross linkable formulations are complex mixtures of resin and various additives incorporated for achieving desired technological and performance characteristics, ease of processing and improving quality. The proper choice of additives and sensitizing agents enable low dose requirements for efficient crosslinking and improvements in various technological properties. The purposes of this work was to investigate the effect of using a binary sensitizer blend of a trifunctional monomer and a rubber in PVC, and develop suitable electron beam cross linkable formulations for wire insulation. This paper presents some aspects of the investigations and development of insulation demonstrated at industrial scale

  4. A complete representation of structure-property relationships in crystals

    Science.gov (United States)

    van de Walle, A.

    2008-06-01

    Whereas structure-property relationships have long guided the discovery and optimization of novel materials, formal quantitative methods to identify such relationships in crystalline systems are beginning to emerge. Among them is cluster expansion, which has been successfully used to parametrize the configurational dependence of important scalar physical properties such as bandgaps, Curie temperatures, equation-of-state parameters and densities of states. However, cluster expansion is currently unable to handle anisotropic properties, a key distinguishing feature of crystalline systems central to the design of modern epitaxial structures and devices. Here, I introduce a tensorial cluster expansion enabling the prediction of fundamental tensor-valued material properties such as elasticity, piezoelectricity, dielectric constants, optoelectric coupling, anisotropic diffusion coefficients, surface energy and stress. As an application, I develop predictive ab initio models of anisotropic properties relevant to the design and optimization of III-V semiconductor epitaxial optoelectronic devices.

  5. Structure–property relationships of iron arsenide superconductors

    OpenAIRE

    Johrendt, Dirk

    2011-01-01

    Iron based superconductors sent material scientists into a renewed excitement reminiscent of the time when the first high-Tc superconductors were discovered 25 years ago. This feature article reviews relationships between structural chemistry and magnetic as well as superconducting properties of iron arsenide compounds, which are outstandingly rich and uniquely coupled. Particular attention is paid to the nature of the structural phase transitions of the parent compounds and their...

  6. 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.

  7. 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.

  8. Changing environments and structure–property relationships in marine biomaterials

    Science.gov (United States)

    Waite, J. Herbert; Broomell, Christopher C.

    2012-01-01

    Summary Most marine organisms make functional biomolecular materials that extend to varying degrees ‘beyond their skins’. These materials are very diverse and include shells, spines, frustules, tubes, mucus trails, egg capsules and byssal threads, to mention a few. Because they are devoid of cells, these materials lack the dynamic maintenance afforded intra-organismic tissues and thus are usually assumed to be inherently more durable than their internalized counterparts. Recent advances in nanomechanics and submicron spectroscopic imaging have enabled the characterization of structure–property relationships in a variety of extra-organismic materials and provided important new insights about their adaptive functions and stability. Some structure–property relationships in byssal threads are described to show how available analytical methods can reveal hitherto unappreciated interdependences between these materials and their prevailing chemical, physical and ecological environments. PMID:22357581

  9. Water Activated Carbon Organics Adsorption Structure - Property Relationships

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2004-08-01

    Full Text Available Investigation (determination of chemical compounds properties need time and many resources when is performed by classical way, or experimentations. Nowadays a number of quantitative structure-property relationships (QSPRs were developed in order to shorting the research and analysis time of chemical properties on classes of compounds. The ability of the molecular descriptor family (MDF was used to produce QSPRs for estimating the adsorption onto activated carbon in water. A number of sixteen organics and theirs adsorption onto activated carbon in water serves for QSPRs obtaining. The MDF methodology include the three-dimensional model of the molecules building using the HyperChem software, MDF members generating using a set of Pre Hypertext Processor (PHP programs, storing using a MySQL database server, and finally with a set of Delphi Multiple Linear Regression programs structure-property relationships findings. A number of 105319 MDF members enter into multiple linear regressions findings. Five from our best QSPRs are presented, one mono-varied, two bi-varied and two tri-varied models. The MDF QSPR methodology has big potential in finding QSPR models and is proved for adsorption onto activated carbon in water of studied organics.

  10. Structure/property relationships in multipass GMA welding of beryllium.

    Energy Technology Data Exchange (ETDEWEB)

    Hochanadel, P. W. (Patrick W.); Hults, W. L. (William L.); Thoma, D. J. (Dan J.); Dave, V. R. (Vivek R.); Kelly, A. M. (Anna Marie); Pappin, P. A. (Pallas A.); Cola, M. J. (Mark J.); Burgardt, P. (Paul)

    2001-01-01

    Beryllium is an interesting metal that has a strength to weight ratio six times that of steel. Because of its unique mechanical properties, beryllium is used in aerospace applications such as satellites. In addition, beryllium is also used in x-ray windows because it is nearly transparent to x-rays. Joining of beryllium has been studied for decades (Ref.l). Typically joining processes include braze-welding (either with gas tungsten arc or gas metal arc), soldering, brazing, and electron beam welding. Cracking which resulted from electron beam welding was recently studied to provide structure/property relationships in autogenous welds (Ref. 2). Braze-welding utilizes a welding arc to melt filler, and only a small amount of base metal is melted and incorporated into the weld pool. Very little has been done to characterize the braze-weld in terms of the structure/property relationships, especially with reference to multipass welding. Thus, this investigation was undertaken to evaluate the effects of multiple passes on microstructure, weld metal composition, and resulting material properties for beryllium welded with aluminum-silicon filler metal.

  11. Relationships among Genetic, Structural, and Functional Properties of Rice Starch.

    Science.gov (United States)

    Kong, Xiangli; Chen, Yaling; Zhu, Ping; Sui, Zhongquan; Corke, Harold; Bao, Jinsong

    2015-07-15

    We determined the relationships among the structural properties, in vitro digestibility, and genetic factors in starches of 14 rice cultivars. Weight-based chain-length distributions in amylopectin ranged from 18.07% to 24.71% (fa, DP 6-12), 45.01% to 55.67% (fb1, DP 13-24), 12.72% to 14.05% (fb2, DP 25-36), and 10.80 to 20.72% (fb3, DP > 36), respectively. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) ranged from 78.5% to 87.5%, 1.2% to 6.0%, and 10.1% to 18.0%, respectively. AAC was negatively correlated with RDS content but positively correlated with RS content in rice starch. The proportion of short chains in amylopectin, i.e. the amount of fraction IIa (FrIIa) fractionated by gel permeation chromatography (GPC), was positively correlated with RDS. Starch synthase IIa (SSIIa) gene controlled the degree of crystallinity, the amount of fa chains of amylopectin. SSIIIa gene controlled the amount of fb1 chains. Wx gene controlled the FrI, FrIIa, RDS, and RS. Starch debranching enzyme isoamylase II (ISA2) gene also controlled the RDS, which may suggest that RDS was also affected by amylopectin structure, although no correlation between them was found. This study indicated that genetics (i.e., starch biosynthesis related genes) controlled the structural properties of starch, and both amylose content and amylopectin fine structure determined functional properties of rice starch (i.e., the digestion), each in a different way. Understanding the "genetics-structure-function" relationships in rice starches will assist plant breeders and food processors in developing new rice varieties and functional foods. PMID:26083191

  12. Structure-functional property relationships in thin film vanadium dioxide

    Science.gov (United States)

    Ko, Changhyun

    2011-12-01

    The metal-insulator transition (MIT) in VO2 induces a dramatic change in electric, dielectric and optical characteristics in the vicinity of room temperature. This fascinating phenomenon has attracted great attention from fundamental research to reveal its mechanisms relevant to the electronic correlation as well as from applications to exploit its effect in novel electronic and photonic devices. This dissertation includes detailed studies on the correlation among microstructure characteristics, functional electrical and dielectric properties, and chemical composition of VO2 thin films as well as the critical effects of synthesis conditions on them and their relationships on the basis of electrical transport measurements, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction analysis. We also demonstrated the novel post-deposition heat treatment method based on photon irradiation to modify MIT properties of VO2 thin films at temperature much lower than the synthesis temperature and showed the excellent stability of the MIT functionality of VO2 thin films through multiple cyclic transition experiments along with electric and structural property characterizations. Using experimental combination of temperature-variable Kelvin probe microscopy, electric property characterizations, and in-depth XPS profiling, we explored the discrepancy of MIT evolution on the film surface and inside bulk region of VO2 films in terms of work function, stoichiometry, and film conductivity. Further, we have introduced novel approaches to investigate MIT phenomena in nanoscale utilizing simple exploratory capacitor and metal-oxide-semiconductor structures based on VO2 thin layers.

  13. Structure-property relationship in organometallic compounds regarding SHG

    Science.gov (United States)

    Heck, Jürgen; Prosenc, Marc H.; Meyer-Friedrichsen, Timo; Holtmann, Jan; Walczuk, Edyta; Dede, Markus; Farrell, Tony; Manning, Anthony R.; Kuball, Hans-Georg; Archetti, Graziano; Wang, Yan-Hua; Liu, Kai; Luo, Yi

    2007-09-01

    Structure-property relationships based on experimental as well as theoretical results will be elucidated. For this purpose different dipolar organometallic compounds were synthesized and characterized. The alteration of the donor and acceptor termini in mono- and dinuclear sesquifulvalene complexes results in spectroscopic and even structural modifications. The structural and 1H NMR spectroscopic changes correlate with the experimentally obtained first hyperpolarizability. The potent electron-donating (D) group [(CpFeCO) II(?-CO)(?-C=CH-)] is combined with different electron-accepting units (A), yielding the push-pull complexes [(CpFeCO) II(?CO)(?-C=CH-CH=A)]. The extent of electron delocalization within the ?-bridge connecting the donor D and the acceptor A can be monitored by means of 1H NMR spectroscopy. A correlation between the 3J(H ?-H ?) coupling constants and the first hyperpolarizability is found, which very much resembles the dependence of the first hyperpolarizability on the bond length alternation. In order to elucidate the dependence of the NLO response on the conformation of triply branched NLOphores, a new series of dendritic D-?-A structures has been synthesized. A combined approach of experiments and computational predictions was applied both on the dendrimers and on the corresponding single-strand chromophores. These results demonstrate that theoretical calculations are able to reproduce experimental results and show the tendency of the effects due to structural changes

  14. 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.

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

    Science.gov (United States)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT concentration, an evolution of PNR?PND (polar nano domains)? micron-domains?macro-domains was found. In addition, a domain hierarchy was observed for the compositions near a morphotropic phase boundary (MPB) on various length scales ranging from nanometer to millimeter. The existence of a domain hierarchy down to the nm scale fulfills the requirement of low domain wall energy, which is necessary for polarization rotation. Thus, upon applying an E-field along direction(s) in a composition near the MPB, low symmetry phase transitions (monoclinic or orthorhombic) can easily be induced. For PMN-30%PT, a complete E-T (electric field vs temperature) diagram has been established. As for Fe-x at.% Ga alloys, short-range Ga-pairs serve as both magnetic and magnetoelastic defects, coupling magnetic domains with bulk elastic strain, and contributing to enhanced magnetostriction. Such short-range ordering was evidenced by a clear 2theta peak broadening on neutron scattering profiles near A2-DO3 phase boundary. In addition, a strong degree of preferred [100] orientation was found in the magnetic domains of Fe-12 at.%Ga and Fe-20 at.%Ga alloys with the A2 or A2+DO3 structures, which clearly indicates a deviation from cubic symmetry; however, no domain alignment was found in Fe-25 at.%Ga with the DO3 structure. Furthermore, an increasing degree of domain fluctuations was found during magnetization rotation, which may be related to short-range Ga-pairs cluster with a large local anisotropy constant, due to a lower-symmetry structure.

  16. Cement-aggregate compatibility and structure property relationships including modelling

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, H.M.; Xi, Y.

    1993-07-15

    The role of aggregate, and its interface with cement paste, is discussed with a view toward establishing models that relate structure to properties. Both short (nm) and long (mm) range structure must be considered. The short range structure of the interface depends not only on the physical distribution of the various phases, but also on moisture content and reactivity of aggregate. Changes that occur on drying, i.e. shrinkage, may alter the structure which, in turn, feeds back to alter further drying and shrinkage. The interaction is dynamic, even without further hydration of cement paste, and the dynamic characteristic must be considered in order to fully understand and model its contribution to properties. Microstructure and properties are two subjects which have been pursued somewhat separately. This review discusses both disciplines with a view toward finding common research goals in the future. Finally, comment is made on possible chemical reactions which may occur between aggregate and cement paste.

  17. Structure-optical property relationships in organometallic sydnones.

    Science.gov (United States)

    Cooper, Thomas M; Hall, Benjamin C; McLean, Daniel G; Rogers, Joy E; Burke, Aaron R; Turnbull, Kenneth; Weisner, Andrew; Fratini, Albert; Liu, Yao; Schanze, Kirk S

    2005-02-17

    As part of an effort to develop a spectroscopic structure-property relationship in platinum acetylide oligomers, we have prepared a series of mesoionic bidentate Pt(PBu3)2L2 compounds containing sydnone groups. The ligand is the series o-Syd-(C6H4-C[triple bond]C)n-H, where n = 1-3, designated as Syd-PEn-H. The terminal oligomer unit consists of a sydnone group ortho to the acetylene carbon. We synthesized the platinum complex (Syd-PEn-Pt), the unmodified ligands (PEn-H), and the unmodified platinum complexes (PEn-Pt). The compounds were characterized by various methods, including X-ray diffraction, 13C NMR, ground-state absorption, fluorescence, phosphorescence, and laser flash photolysis. From solving the structure of Syd-PE1-Pt, we find the angle between the sydnone group and the phenyl group is 45 degrees . By comparison of the 13C NMR spectra of the sydnone-containing ligands, the sydnone complexes with the corresponding unmodified ligands and complexes not containing the sydnone group, the sydnone group is shown to polarize the nearest acetylenes and have a charge-transfer interaction with the platinum center. Ground-state absorption spectra of the complexes in various solvents give evidence that the Syd-PE1-Pt complex has an excited state less polar than the ground state, while the PE1-Pt complex has an excited state more polar than the ground state. In all the higher complexes the excited state is more polar than the ground state. The phosphorescence spectrum of the Syd-PE1-Pt complex has an intense vibronic progression distinctly different from the PE1-Pt complex. The sydnone effect is small in Syd-PE2-Pt and negligible in Syd-PE3-Pt. From absorption and emission spectra, we measured the singlet-state energy E(S), the triplet-state energy E(T), and the singlet-triplet splitting Delta E(ST). By comparison with energies obtained from the unmodified complexes, attachment of the sydnone lowers E(S) by approximately 0.1 eV and raises E(T) by approximately 0.1 eV. As a result, the sydnone group lowers Delta E(ST) by approximately 0.2 eV. The trends suggest one of the triplet-state singly occupied molecular orbitals (SOMOs) is localized on the sydnone group, while the other SOMO resides on the rest of the ligand. PMID:16833406

  18. Investigation of ion-conducting ormolytes : structure-property relationships

    OpenAIRE

    Judeinstein, Patrick; Schmidt, Helmut K.; Titman, J.; Stamm, M.

    1994-01-01

    Hybrid organic-inorganic composites with ionic properties, so called ormolytes (organically modified electrolytes) have been prepared by the sol-gel process from mixtures of tetraethoxysilane, tetraethylene glycol, and lithium salt. They show ionic conductivity up to 5 x 10-5 ?-1 cm-1, with activation energies around 0.6 eV. Their properties have been related to their structure using a multitechnique approach (IR, DSC, NMR, SAXS). These materials can be described as diphasic systems wit...

  19. Structure-Property Relationships for Branched Worm-Like Micelles

    Science.gov (United States)

    Beaucage, Gregory; Rai, Durgesh

    2013-03-01

    Micellar solutions can display a wide range of phase structure as a function of counter ion content, surfactant concentration, and the presence of ternary components. Under some conditions, common to consumer products, extended cylindrical structures that display persistence and other chain features of polymers are produced. These worm-like micelles (WLMs) can form branched structures that dynamically change under shear and even in quiescent conditions. The rheology of these branched WLMs is strongly dependent on migration of the branch points, and the dynamics of branch formation and removal. Persistence and other polymer-based descriptions are also of importance. We have recently developed a scattering model for branched polyolefins and other topologically complex materials that can quantify the branching density, branch length, branch functionality and the hyperbranch (branch-on-branch) content of polymers. This work is being extended to study branching in WLMs in work coupled with Ron Larson at UMich to predict rheological properties.

  20. Structure-mechanics property relationship of waste derived biochars.

    Science.gov (United States)

    Das, Oisik; Sarmah, Ajit K; Bhattacharyya, Debes

    2015-12-15

    The widespread applications of biochar in agriculture and environmental remediation made the scientific community ignore its mechanical properties. Hence, to examine the scope of biochar's structural applications, its mechanical properties have been investigated in this paper through nanoindentation technique. Seven waste derived biochars, made under different pyrolysis conditions and from diverse feedstocks, were studied via nanoindentation, infrared spectroscopy, X-ray crystallography, thermogravimetry, and electron microscopy. Following this, an attempt was made to correlate the biochars' hardness/modulus with reaction conditions and their chemical properties. The pine wood biochar made at 900°C and 60min residence time was found to have the highest hardness and elastic modulus of 4.29 and 25.01GPa, respectively. It was shown that a combination of higher heat treatment (?500°C) temperature and longer residence time (~60min) increases the values of hardness and modulus. It was further realized that pyrolysis temperature was a more dominant factor than residence time in determining the final mechanical properties of biochar particles. The degree of aromaticity and crystallinity of the biochar were also correlated with higher values of hardness and modulus. PMID:26322726

  1. Crystal structure-physical property relationships in perovskites

    International Nuclear Information System (INIS)

    The crystal structures of seven compounds with the perovskite structure are analysed in terms of their cation coordination polyhedra. The analysis shows that the occurrence of ferroelectricity in a perovskite of composition ABO3 requires the ratio of cuboctahedral A-ion volume to octahedral B-ion volume to be exactly five, and that there is a minimum octahedral B-ion volume associated with ferroelectric properties. The analysis also suggests that each ion may be assigned a characteristic range of polyhedral volumes which is transferable to other crystal structures. The methodology is applied to two perovskite ceramic systems, lead zirconate titanate (PZT) and lead zinc niobate (PZN). The phase diagram of the PZT system is rationalized in terms of the coordination polyhedra of the lead, zirconium and titanium ions, and a critical lead cuboctahedral volume is defined at the morphotropic phase boundary. The effect of the lanthanum ion in stabilizing the tetragonal phase to a higher Zr/Ti ratio and in reducing the Curie temperature is also discussed. In the PZN system the polyhedral analysis permits a rationalization of the behaviour of seven different additives in inhibiting the formation of a pyrochlore phase, Pb3Nb4O13, during the fabrication of PZN ceramic. The potential of the technique as a predictive structural tool is also assessed. (orig.)

  2. 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.

  3. 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.

  4. Structure-Property Relationships in Sulfonated Pentablock Copolymers

    Science.gov (United States)

    Choi, Jae-Hong; Willis, Carl; Winey, Karen I.

    2011-03-01

    Membranes of pentablock copolymers consisting of poly(tert-butyl styrene) (TBS), hydrogenated polyisoprene (HI), and partially sulfonated poly(styrene-ran-styrene sulfonate) (SS) were studied using small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The TBS-HI-SS-HI-TBS pentablock copolymer in solution forms spherical micelles with a core of SS and a corona of solvated HI and TBS. The spherical micelles in solution compact as the solvent evaporates and some of SS cores merge to form interconnected SS microdomains without substantially changing their shape. The number of connections increases with the volume fraction of the SS block, which increases with sulfonation level. The structure does not have long-range order, because strong ionic interactions prevent extensive rearrangement. The morphologies of the sulfonated pentablock copolymers will be correlated with their transport properties.

  5. Structure - property relationships in ceramic matrix composites reinforced using woven fibres

    International Nuclear Information System (INIS)

    Micro-structure - property relationships are an important topic in materials science. In textile composites, limited effort has been devoted to establishing these relationships, although these materials possess a highly heterogeneous structure. The mechanical behaviour of ceramic or carbon matrix composites reinforced with woven bundles was investigated. It is shown that composite structure and constituent properties control damage, stress redistribution and flaw population truncature processes. These processes determine the mechanical behaviour, fracture and properties including failure strength and fracture toughness. The influence of interfaces is also discussed. (author)

  6. 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...

  7. Structure property relationships in polycarbonate/polydimethylsiloxane copolymers

    International Nuclear Information System (INIS)

    Block copolymers based on polycarbonate (PC) and polydimethylsiloxane (PDMS) have been known for over 40 years. These materials have achieved commercial success due to a favorable combination of low temperature impact, melt processibility, weathering resistance and unique surface properties. Most commercial products are opaque due to scattering by the PDMS domains dispersed in the PC matrix. By controlling synthesis conditions, optically opaque or transparent materials may result from the same combination of base monomers and both types of materials have been prepared and characterized. Lower PDMS block lengths lead to higher levels of light transmission. Opaque materials typically have siloxane domains in the 5 um region while low haze products can be achieved when domains are less than 20 nm. Small siloxane domain copolymers exhibit considerable mixing of PC into the PDMS blocks. This likely alters the refractive index of the PDMS phase and contributes to the low haze measured in these copolymers. (author)

  8. 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.

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

    OpenAIRE

    Lee, Nayeon; Horstemeyer, M. F.; Rhee, Hongjoo; Nabors, Ben; LIAO, JUN; Williams, Lakiesha N.

    2014-01-01

    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 k...

  10. 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.

  11. 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.

  12. Grain Boundary Plane Orientation Fundamental Zones and Structure-Property Relationships.

    Science.gov (United States)

    Homer, Eric R; Patala, Srikanth; Priedeman, Jonathan L

    2015-01-01

    Grain boundary plane orientation is a profoundly important determinant of character in polycrystalline materials that is not well understood. This work demonstrates how boundary plane orientation fundamental zones, which capture the natural crystallographic symmetries of a grain boundary, can be used to establish structure-property relationships. Using the fundamental zone representation, trends in computed energy, excess volume at the grain boundary, and temperature-dependent mobility naturally emerge and show a strong dependence on the boundary plane orientation. Analysis of common misorientation axes even suggests broader trends of grain boundary energy as a function of misorientation angle and plane orientation. Due to the strong structure-property relationships that naturally emerge from this work, boundary plane fundamental zones are expected to simplify analysis of both computational and experimental data. This standardized representation has the potential to significantly accelerate research in the topologically complex and vast five-dimensional phase space of grain boundaries. PMID:26498715

  13. Structure-Property Relationships of Polymer-Based Nanocomposites with Polyhedral Oligomeric Silsesquioxanes as Nanofillers

    OpenAIRE

    Hao, Ning

    2007-01-01

    Polymer-based nanocomposites were prepared by blending Polyhedral Oligomeric Silsesquioxane (POSS) with different sidegroups, PhenethylPOSS and Chloropropyl-POSS, into Poly(bisphenol A carbonate) (PBAC) and polystyrene (PS) respectively. The samples were obtained by film-casting under optimized conditions. The structure-property relationships of the nanocomposites were investigated by dielectric relaxation spectroscopy and gas transport measurements. PhenethylPOSS can be blended into PBAC on ...

  14. 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.

  15. The Relationship of Physical Property Indicators and Clay Soil Structural Strength of Tomsk Oblast Territory

    Science.gov (United States)

    Kramarenko, V. V.; Nikitenkov, A. N.; Molokov, V. Y.; Matveenko, I. A.; Shramok, A. V.

    2015-11-01

    The article deals with the characteristic of initial condition in fine-grained soils - its structural strength - pstr. Estimation and measurement of this factor at soil testing are of primary importance for defining its physical and mechanical properties as well as for subsequent calculation of foundation settlements that is insufficiently covered in Code of practice, national standard and inefficiently applicable in practice of engineering geological investigations. The article reveals the relationship between soil physical property, its occurrence depth, which will make possible to forecast pstr over the given territory.

  16. Squeezing a gel to establish network structure-transport property relationships

    Science.gov (United States)

    Chan, Edwin; Nadermann, Nichole; McLeod, Kelly; Tew, Greg

    2015-03-01

    Gels are used in many applications, ranging from drug delivery to water purification, where regulating transport of a particular permeant is critical. The structure of the gel determines its transport properties but developing the gel structure-transport property relationships often require multiple measurement techniques. In this work, we demonstrate poroelastic relaxation indentation (PRI) as a single measurement tool to establish the relationships between the polymer network structure and the transport properties of well-defined hydrogel networks synthesized via a thiol-norbornene click reaction of poly(ethylene glycol) (PEG) chains. We use PRI to quantify the mechanical and transport properties of a series of ``click'' hydrogels with different crosslink densities. By applying various thermodynamic network swelling models to the describe the mechanical response of these gels as measured from PRI, we are able to extract thermodynamic parameters of these hydrogels including the Flory chi parameter and the mesh size. We validate our approach by comparing the thermodynamic parameters obtained from PRI with results from neutrons scattering studies of the same series of hydrogels.

  17. Significance of structure–property relationship in alumina based porcelain insulators to achieve quality

    Indian Academy of Sciences (India)

    Parvati Ramaswamy; S Vynatheya; S Seetharamu

    2005-12-01

    The catastrophic failures of porcelain insulators in power lines can be minimized by understanding the structure–property relationship that governs the performance. A study addressing the materials aspects has been conducted on alumina based porcelain insulators used in 25 kV railway traction lines. This article asserts the controls exercised by chemical composition, crystalline structural phases and microstructure on the functional reliability and durability of the insulators. Influences of the total alumina, -Al2O3 (corundum) and -quartz contents, microstructural features including morphologies of mullite needles, quartz and corundum grains in the alumino silicate glassy matrix, large inhomogeneities in matrix constituents and composition have been highlighted.

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

    Science.gov (United States)

    Hollowell, Kendall Birckhead

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

  19. 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.

  20. 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

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

    Science.gov (United States)

    Rmaile, Hassan H.

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

  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. Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes

    Science.gov (United States)

    Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

    2015-10-01

    Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials. Electronic supplementary information (ESI) available: The convergence test used in DFT calculation and the validation of the assumption of negligible Poisson effects can be found in the ESI, along with illustrations of total strain energy and the reaction force response of carbon-carbon, Al-O, and Si-O beam elements, von Mises stress and ? distributions of AlSiNT14 and 16, potential energy types, and boundary conditions in the simulations. The mol files of AlSiNT models with various diameters are also appended. See DOI: 10.1039/c5nr03365a

  4. 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.

  5. Structure-morphology-property relationships of non-perfluorinated proton-conducting membranes.

    Science.gov (United States)

    Peckham, Timothy J; Holdcroft, Steven

    2010-11-01

    A fundamental understanding of structure-morphology-property relationships of proton exchange membranes (PEMs) is crucial in order to improve the cost, performance, and durability of PEM fuel cells (PEMFCs). In this context, there has been an explosion over the past five years in the volume of research carried out in the area of non-perfluorinated, proton-conducting polymer membranes, with a particular emphasis on exploiting phase behavior associated with block and graft copolymers. This progress report highlights a selection of interesting studies in the area that have appeared since 2005, which illustrate the effects of factors such as acid and water contents and morphology upon proton conduction. It concludes with an outlook on future directions. PMID:20848594

  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. Elucidation of structure-to-property relationships of piezoresistive polymer-carbon nanotube nanocomposites

    Science.gov (United States)

    Fang, Weiqing; Leung, Siu N.

    2015-07-01

    Polymeric nanocomposites (PNC) filled with carbon nanotubes (CNTs) possess superior multifunctionality, including electrical, thermal, and mechanical properties, making them an emerging family of advanced and multifunctional materials. In recent years, flexible polymer/CNT nanocomposites are increasingly being considered as promising alternatives to conventional smart materials. Their piezoresistive behaviours have led to many potential applications in strain sensing. Despite extensive experimental and theoretical research, the underlying mechanisms for polymer/CNT nanocomposites' piezoresistive behaviours have yet been elucidated. This paper reports comprehensive investigations on the mechanisms and the structure-to-property relationships of these piezoresistive nanocomposites. Quantitative analyses revealed that piezoresistivity of polymer/CNT nanocomposites is predominantly governed by the three mechanisms related to the strain-induced morphological evolution of the CNT network embedded in the polymer matrix. Furthermore, both CNT content and CNT alignment are key structural parameters that affect the contribution of different mechanisms on PNCs' piezoresistivity and the sensitivity of flexible PNCs as strain sensors. For PNC filled with high content of randomly dispersed CNTs, the piezoresistivity was predominantly caused by the breakage of a complex conductive network into two or more simpler conductive paths. For PNC filled with low content of highly aligned CNTs, the piezoresistivity was mainly contributed by the complete disruption of originally interconnected CNTs in electrically conductive pathways.

  8. 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.

  9. 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.

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

    Science.gov (United States)

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

    2015-11-01

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

  11. 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

  12. Structure - property relationships in ceramic matrix composites reinforced using woven fibres; Relations structure-proprietes dans les composites a matrice ceramique et renfort textile

    Energy Technology Data Exchange (ETDEWEB)

    Lamon, J. [Laboratoire des Composites Thermostructuraux (LCTS), 33 - Pessac (France)

    2005-11-15

    Micro-structure - property relationships are an important topic in materials science. In textile composites, limited effort has been devoted to establishing these relationships, although these materials possess a highly heterogeneous structure. The mechanical behaviour of ceramic or carbon matrix composites reinforced with woven bundles was investigated. It is shown that composite structure and constituent properties control damage, stress redistribution and flaw population truncature processes. These processes determine the mechanical behaviour, fracture and properties including failure strength and fracture toughness. The influence of interfaces is also discussed. (author)

  13. Processing-structure-property relationships of carbon nanotube and nanoplatelet enabled piezoresistive sensors

    Science.gov (United States)

    Luo, Sida

    Individual carbon nanotubes (CNTs) possess excellent piezoresistive performance, which is manifested by the significant electrical resistance change when subject to mechanical deformation. In comparison to individual CNTs, the CNT thin films, formed by a random assembly of individual tubes or bundles, show much lower piezoresistive sensitivity. Given the progress made to date in developing CNT ensemble based-piezoresistive sensors, the related piezoresistive mechanism(s) are still not well understood. The crucial step to obtain a better understanding of this issue is to study the effects of CNT structure in the dispersion on the piezoresistivity of CNT ensemble based-piezoresistive sensors. To reach this goal, my Ph.D. research first focuses on establishing the processing-structure-property relationship of SWCNT thin film piezoresistive sensors. The key accomplishment contains: 1) developing the combined preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) method to quantitatively characterized SWCNT particle size in dispersions under various sonication conditions; 2) designing combined ultrasonication and microfluidization processing protocol for high throughput and large-scale production of high quality SWCNT dispersions; 3) fabricating varied SWCNT thin film piezoresistive sensors through spray coating technique and immersion-drying post-treatment; and 4) investigating the effect of microstructures of SWCNTs on piezoresistivity of SWCNT thin film sensors. This experimental methodology for quantitative and systematic investigation of the processing-structure-property relationships provides a means for the performance optimization of CNT ensemble based piezoresistive sensors. As a start to understand the piezoresistive mechanism, the second focus of my Ph.D. research is studying charge transport behaviors in SWCNT thin films. It was found that the temperature-dependent sheet resistance of SWCNT thin films could be explained by a 3D variable range hopping (3D-VRH) model. More importantly, a strong correlation between the length of SWCNTs and the VRH parameter T0, indicating the degree of disorder of the electronic system, has been identified. With the structure dependent transport mechanism study, a very interesting topic - how T0 changes when SWCNT thin film is under a mechanical deformation, would be helpful for better understanding the piezoresistive mechanism of SWCNT thin film sensors. As demonstrated in transport mechanism study, SWCNT thin film exhibits a negative temperature coefficient (NTC) of resistance. In contrast, another family of carbon nanomaterials, graphite nanoplatelets (GNPs), shows positive temperature coefficient (PTC) of resistance, attributed to their metallic nature. Therefore, upon a wise selection of mass ratio of SWCNTs to GNPs for fabrication of hybrid SWCNT/GNP thin film piezoresistive sensors, a near zero temperature coefficients of resistance in a broad temperature range has been achieved. This unique self-temperature compensation feature along with the high sensitivity of SWCNT/GNP hybrid sensors provides them a vantage for readily and accurately measuring the strain/stress levels in different conditions. With the unique features of SWCNT/GNP hybrid thin film sensors, my future work will focus on application exploration on SWCNT/GNP thin film sensor based devices. For example, we have demonstrated that it is potential for man-machine interaction and body monitoring when coating the hybrid sensor on highly stretchable nitrile glove. The structure health monitoring (SHM) of composite materials could also be realized by coating the thin film sensor on a glass fiber surface and then embedding the fiber sensor in composite structure.

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

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, Marcel; Mauro, John C.; Smedskjær, Morten Mattrup; Ellison, Adam J.; Youngman, Randall E.; Yue, Yuanzheng

    2012-01-01

    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-pr...

  15. Structure-property relationships of meta-kerateine biomaterials derived from human hair.

    Science.gov (United States)

    Richter, Jillian R; de Guzman, Roche C; Greengauz-Roberts, Olga K; Van Dyke, Mark

    2012-01-01

    The structure-property relationships of kerateine materials were studied by separating crude hair extracts into two protein sub-fractions, referred to as ?- and ?-kerateines, followed by their de novo recombination into meta-kerateine hydrogels, sponges and films. The kerateine fractions were characterized using electrophoresis and mass spectrometry, which revealed that the ?-fraction contained complexes of type I and type II keratins and that the ?-fraction was primarily protein fragments of the ?-fraction along with three proteins of the KAP-1 family. Meta-kerateine materials with increased amounts of ?-kerateines showed diminished physical, mechanical and biological characteristics. Most notably, materials with higher ?-content formed less elastic and less solid-like hydrogels and sponges that were less hydrolytically stable. In addition, a model biological assay showed that meta-kerateine films with greater amounts of ?-kerateines were less supportive of hepatocyte attachment. Investigation into the mechanism of attachment revealed that hepatocyte adhesion to meta-kerateines is not mediated by the ?1 integrin subunit, despite the presence of LDV binding motifs within the type I ?-keratins. This work to define the role of protein composition on biomaterial function is essential for the optimization of keratin biomaterials for biomedical applications. PMID:21911088

  16. Quantitative structure-property relationship modeling of remote liposome loading of drugs.

    Science.gov (United States)

    Cern, Ahuva; Golbraikh, Alexander; Sedykh, Aleck; Tropsha, Alexander; Barenholz, Yechezkel; Goldblum, Amiram

    2012-06-10

    Remote loading of liposomes by trans-membrane gradients is used to achieve therapeutically efficacious intra-liposome concentrations of drugs. We have developed Quantitative Structure Property Relationship (QSPR) models of remote liposome loading for a data set including 60 drugs studied in 366 loading experiments internally or elsewhere. Both experimental conditions and computed chemical descriptors were employed as independent variables to predict the initial drug/lipid ratio (D/L) required to achieve high loading efficiency. Both binary (to distinguish high vs. low initial D/L) and continuous (to predict real D/L values) models were generated using advanced machine learning approaches and 5-fold external validation. The external prediction accuracy for binary models was as high as 91-96%; for continuous models the mean coefficient R(2) for regression between predicted versus observed values was 0.76-0.79. We conclude that QSPR models can be used to identify candidate drugs expected to have high remote loading capacity while simultaneously optimizing the design of formulation experiments. PMID:22154932

  17. Neuroprotective and cognition-enhancing properties of MK-801 flexible analogs. Structure-activity relationships.

    Science.gov (United States)

    Bachurin, S; Tkachenko, S; Baskin, I; Lermontova, N; Mukhina, T; Petrova, L; Ustinov, A; Proshin, A; Grigoriev, V; Lukoyanov, N; Palyulin, V; Zefirov, N

    2001-06-01

    Neuroprotective and biobehavioral properties of a series of novel open chain MK-801 analogs, as well as their structure-activity relationships have been investigated. Three groups of compounds were synthesized: monobenzylamino, benzhydrylamino, and dibenzylamino (DBA) analogs of MK-801. It was revealed that DBA analogs exhibit pronounced glutamate-induced calcium uptake blocking properties and anti-NMDA activity. The hit compound of DBA series, NT-1505, was investigated for its ability to improve cognition functions in animal model of Alzheimer's disease type dementia, simulated by treating animals with cholinotoxin AF64A. The results from an active avoidance test and a Morris water maze test showed that experimental animals, treated additionally with NT-1505, exhibited much better learning ability and memory than the control group (AF64A treated) and close to that of the vehicle group of animals (treated with physiological solution). Study of NT-1505 influence on locomotor activity revealed that it is characterized by a spectrum of behavioral activity radically different from that of MK-801, and in contrast to the latter one does not produce any psychotomimetic side effects in the therapeutically significant dose interval. The computed docking of MK-801 and its flexible analogs on the NMDA receptor elucidated the crucial role of the hydrogen bond formed between these compounds and the asparagine residue for magnesium binding in the NMDA receptor. It was suggested that strong hydrophobic interaction between MK-801 and the hydrophobic pocket in the NMDA receptor-channel complex determines much higher irreversibility of this adduct compared to the intermediates formed between this site and Mg ions or flexible DBA derivatives, which might explain the absence of PCP-like side effects of the latter compounds. PMID:11462774

  18. Quantitative Structure-Property Relationship (QSPR) Modeling of Drug-Loaded Polymeric Micelles via Genetic Function Approximation

    OpenAIRE

    Wu, Wensheng; Zhang, Canyang; Lin, Wenjing; Chen, Quan; Guo, Xindong; Qian, Yu; Zhang, Lijuan

    2015-01-01

    Self-assembled nano-micelles of amphiphilic polymers represent a novel anticancer drug delivery system. However, their full clinical utilization remains challenging because the quantitative structure-property relationship (QSPR) between the polymer structure and the efficacy of micelles as a drug carrier is poorly understood. Here, we developed a series of QSPR models to account for the drug loading capacity of polymeric micelles using the genetic function approximation (GFA) algorithm. These...

  19. 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 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)

  20. Environmental properties of long-chain alcohols. Structure-activity Relationship for Chronic Aquatic Toxicity

    DEFF Research Database (Denmark)

    Schaefers, Christoph; Sanderson, Hans; Boshof, Udo; Jurling, Hans; Belanger, Scott; Dyer, Scott; Nielsen, Allen; Willing, Andreas; Gamon, Konrad; Kasai, Yutaka; Eadsford, Charles; Fisk, Peter; Girling, Andrew

    2009-01-01

    Daphnia magna reproduction tests were performed with C10, C12, C14 and C15 alcohols to establish a structure-activity relationship of chronic effects of long-chain alcohols. The data generation involved substantial methodological efforts due to the exceptionally rapid biodegradability of the test substances and the need to test as close as possible to their water solubility limits. Test concentrations were determined by GC-MS before and after test solution renewal. Whereas apparent toxicity base...

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

    Science.gov (United States)

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

    2015-06-01

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

  2. 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

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

    OpenAIRE

    Köping-Höggård, 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...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-28

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

  5. Using transgenic poplars to elucidate the relationship between the structure and the thermal properties of lignins.

    Science.gov (United States)

    Baumberger, Stéphanie; Dole, Patrice; Lapierre, Catherine

    2002-04-10

    In an attempt to draw relationships between the molecular structure and the thermal behavior of lignins, thermomechanical analyses were run on six milled wood and enzyme poplar lignin fractions prepared from genetically modified and control woods. All the lignin samples displayed similar thermal profiles with a clear inflection point assigned to the glass transition point. The temperature (T(g)) at which this transition occurs showed large variations from 170 to 190 degrees C, depending both on the genetic modification and on the age of the tree. These variations were found to be closely related to the condensation degree of lignins evaluated by thioacidolysis. PMID:11929312

  6. Structure-processing-property relationships for polymer interphases in fiber reinforced composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Drzal, L.T. [Michigan State Univ., East Lansing, MI (United States)

    1995-12-31

    When polymer matrix composite materials are fabricated, polymers are processed to surround each reinforcing element while they are fluid and then they solidify in intimate contact with the reinforcement surface. For thermoset matrices, chemisorption of constituents, segregation of components. and processing constraints all can influence the resulting structure of the polymer in its solidified state. For thermoplastic matrices, segregation by molecular weight, morphological changes resulting from crystallization or additive segregation can also control the final matrix structure. In addition the surface of the fibers is coated with chemical agents that can also interact with the polymer. Examples will be given to illustrate the effect of the structure of this polymer interphase on adhesion. It will be shown that in some cases if the resulting polymer structure is known, adhesion and composite properties can be predicted.

  7. 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...

  8. 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.

  9. Quantitative structure-property relationship (QSPR) modeling of drug-loaded polymeric micelles via genetic function approximation.

    Science.gov (United States)

    Wu, Wensheng; Zhang, Canyang; Lin, Wenjing; Chen, Quan; Guo, Xindong; Qian, Yu; Zhang, Lijuan

    2015-01-01

    Self-assembled nano-micelles of amphiphilic polymers represent a novel anticancer drug delivery system. However, their full clinical utilization remains challenging because the quantitative structure-property relationship (QSPR) between the polymer structure and the efficacy of micelles as a drug carrier is poorly understood. Here, we developed a series of QSPR models to account for the drug loading capacity of polymeric micelles using the genetic function approximation (GFA) algorithm. These models were further evaluated by internal and external validation and a Y-randomization test in terms of stability and generalization, yielding an optimization model that is applicable to an expanded materials regime. As confirmed by experimental data, the relationship between microstructure and drug loading capacity can be well-simulated, suggesting that our models are readily applicable to the quantitative evaluation of the drug-loading capacity of polymeric micelles. Our work may offer a pathway to the design of formulation experiments. PMID:25780923

  10. 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.

  11. Investigating the Structure-Property Relationships of Aqueous Self-Assembled Materials

    Science.gov (United States)

    Krogstad, Daniel Vincent

    The components of all living organisms are formed through aqueous self-assembly of organic and inorganic materials through physical interactions including hydrophobic, electrostatic, and hydrogen bonding. In this dissertation, these physical interactions were exploited to develop nanostructured materials for a range of applications. Peptide amphiphiles (PAs) self-assemble into varying structures depending on the physical interactions of the peptides and tails. PA aggregation was investigated by cryo-TEM to provide insight on the effects of varying parameters, including the number and length of the lipid tails as well as the number, length, charge, hydrophobicity, and the hydrogen bonding ability of the peptides. It was determined that cylindrical micelles are most commonly formed, and that specific criteria must be met in order to form spherical micelles, nanoribbons, vesicles or less ordered aggregates. Controlling the aggregated structure is necessary for many applications---particularly in therapeutics. Additionally, two-headed PAs were designed to act as a catalyst and template for biomimetic mineralization to control the formation of inorganic nanomaterials. Finally, injectable hydrogels made from ABA triblock copolymers were synthesized with the A blocks being functionalized with either guanidinium or sulfonate groups. These oppositely charged polyelectrolyte endblocks formed complex coacervate domains, which served as physical crosslinks in the hydrogel network. The mechanical properties, the network structure, the nature of the coacervate domain and the kinetics of hydrogel formation were investigated as a function of polymer concentration, salt concentration, pH and stoichiometry with rheometry, SAXS and SANS. It was shown that the mechanical properties of the hydrogels was highly dependent on the structural organization of the coacervate domains and that the properties could be tuned with polymer and salt concentration. Polymer and salt concentration were also shown to play roles in determining the size and density of the coacervate domains. Additionally, 20 wt% hydrogels were shown to form through a nucleation and growth pathway, in which the coacervate domains formed within minutes, the BCC structure was predominant within 100 minutes, but the equilibrium structure was not achieved for months. Ultimately, the work presented in this dissertation has resulted in an improved understanding of the physical interactions that are needed for self-assembly and may eventually lead to smarter design of nanomaterials for therapeutic, electronic and mechanical applications.

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

    Science.gov (United States)

    Neilson, James R.

    2011-12-01

    A grand challenge in materials science and chemistry revolves around the preparation of materials with desired properties by controlling structure on multiple length scales. Biology approaches this challenge by evolving tactics to transform soluble precursors into materials and composites with macro-scale and atomic precision. Studies of biomineralization in siliceous sponges led to the discovery of slow, catalytic hydrolysis of molecular precursors in the biogenesis of silica skeletal elements with well defined micro- and nano-scale architectures. However, the role of aqueous hydrolysis in the limit of kinetic control is not well understood; this allows us to form a central hypothesis: that the kinetics of hydrolysis modulate the structures of materials and their properties. As a model system, the diffusion of a simple hydrolytic catalyst (such as ammonia) across an air-water interface into a metal salt solution reproduces some aspects of the chemistry found in biomineralization, namely kinetic and vectorial control. Variation of the catalyst concentration modulates the hydrolysis rate, and thus alters the resulting structure of the inorganic crystals. Using aqueous solutions of cobalt(II) chloride, each product (cobalt hydroxide chloride) forms with a unique composition, despite being prepared from identical mother liquors. Synchrotron X-ray total scattering methods are needed to locate the atomic positions in the material, which are not aptly described by a traditional crystallographic unit cell due to structural disorder. Detailed definition of the structure confirms that the hydrolysis conditions systematically modulate the arrangement of atoms in the lattice. This tightly coupled control of crystal formation and knowledge of local and average structures of these materials provides insight into the unusual magnetic properties of these cobalt hydroxides. The compounds studied show significant and open magnetization loops with little variation with composition or structure, yet subtle and systematic changes in the mean-field spin interaction strength and spin entropy loss. Meanwhile, neutron powder diffraction reveals a fully compensated ?eel state; a detailed analysis of the local structure defines the aperiodic clusters of polyhedra responsible for magnetic order. The rate of hydrolysis of metal precursors modulates the disposition of these polyhedral clusters. The strategy of kinetically controlling aqueous hydrolysis also extends to the formation of stoichiometrically ordered bimetallic crystals [MSn(OH)6], where the hydrolysis behavior for dissimilar metal cations must be controlled via counteranions or precursor selection. In the formation of these ordered double perovskite hydroxides, the rate of hydrolysis is held constant in the limit of kinetic control. Instead, the propensities of different cations to undergo controlled hydrolysis are probed by their ability to form ordered crystals. Collectively, these studies demonstrate how systematic variation in the kinetic conditions of materials preparation and the character of each solute control the structure and properties of materials, with a precision not attainable through traditional or near-equilibrium approaches.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-07

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

  14. Relationships between structural and luminescence properties in Eu 3+-doped new calcium borohydroxyapatite

    Science.gov (United States)

    Ternane, R.; Panczer, G.; Cohen-Adad, M. Th; Goutaudier, C.; Boulon, G.; Kbir-Ariguib, N.; Trabelsi-Ayedi, M.

    2001-02-01

    In apatitic structures such as Ca 10(PO 4) 6(OH) 2, borate groups are introduced as planar and regular BO 33- and substitute phosphate and hydroxyl groups. In order to study the influence in the change of the coordination environment of the cationic sites on the luminescent properties of RE ions doping calcium borohydroxyapatite, the time-resolved luminescence of the Eu 3+ ion in this new compound is reported. Site-selective excitation of the 5D 0 level was performed and luminescence decay times of each Eu 3+ site were measured at 77 K. By comparison with Eu-doped boron free apatites, it is shown that borate groups induce perturbations in the Eu 3+ luminescence features. The spectroscopic results are discussed in terms of possible charge compensation mechanisms correlated with the structural data.

  15. Structure–property relationships of electroluminescent polythiophenes: role of nitrogen-based heterocycles as side chains

    Indian Academy of Sciences (India)

    S Radhakrishnan; S J Ananthakrishnan; N Somanathan

    2011-07-01

    A series of conjugated polythiophenes containing nitrogen-containing heterocycles as side chain, with differing substituent nature and linkage have been studied using quantum-chemical calculations. The optical properties of synthesized polymers were compared with that of model compounds with intricate structural variations. The theoretically predicted optical characteristics are correlated with the experimentally determined parameters. Experimentally determined band gap and absorption maxima found to follow the predicted trends. Single emissive layer polymeric light emitting diodes are fabricated and the structural influence on photo- and electro-emission was studied in detail. The study shows that the nature of side chain substituent such as number/position of nitrogen atoms and mode of linking of side chain plays a crucial role in deciding the geometry which in turn controls the voltage response of the electroluminescence.

  16. Structure-Property relationship for H covered Fe3 O4 (001)

    Science.gov (United States)

    Liu, Fangyang; Kizilkaya, Orhan; Sprunger, Phillip; Kurtz, Richard; Jin, Rongying; Zhang, Jiandi; Plummer, Ward

    2015-03-01

    Magnetite (Fe3O4), the oldest permanent magnet, is still being studied, due to the fascinating surface properties. Clean B layer terminated Fe3O4(001) surface exhibits a (?2 × ?2)R45 reconstruction, which as reported by LEED experiments can be removed by hydrogen adsorption at RT. However, the mechanism of this surface structural change is unknown. Combining HREELS, LEIS, ARXPS, UPS and XANES, we discovered a very unusual adsorption mechanism. Hydrogen appears to be bonded to the surface iron atoms not oxygen as expected. We observe H-Fe vibration mode with HREELS while no OH mode is present. Furthermore LEIS experiments confirmed H is on the iron atoms site. We will discuss the adsorption mechanism and electronic structure change with information provided by the core level photoemission techniques. This work was supported by Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy.

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

    Directory of Open Access Journals (Sweden)

    Ester Betoret

    2015-02-01

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

  18. 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...

  19. 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.

  20. 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

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Prichard, P.D.

    1998-02-23

    Iron-aluminum alloys have been extensively evaluated as semi-continuous product such as sheet and bar, but have not been evaluated by net shape P/M processing techniques such as metal injection molding. The alloy compositions of iron-aluminum alloys have been optimized for room temperature ductility, but have limited high temperature strength. Hot extruded powder alloys in the Fe-Al-Si system have developed impressive mechanical properties, but the effects of sintering on mechanical properties have not been explored. This investigation evaluated three powder processed Fe-Al-Si alloys: Fe-15Al, Fe-15Al-2.8Si, Fe-15Al-5Si (atomic %). The powder alloys were produced with a high pressure gas atomization (HPGA) process to obtain a high fraction of metal injection molding (MIM) quality powder (D{sub 84} < 32 {micro}m). The powders were consolidated either by P/M hot extrusion or by vacuum sintering. The extruded materials were near full density with grain sizes ranging from 30 to 50 {micro}m. The vacuum sintering conditions produced samples with density ranging from 87% to 99% of theoretical density, with an average grain size ranging from 26 {micro}m to 104 {micro}m. Mechanical property testing was conducted on both extruded and sintered material using a small punch test. Tensile tests were conducted on extruded bar for comparison with the punch test data. Punch tests were conducted from 25 to 550 C to determine the yield strength, and fracture energy for each alloy as a function of processing condition. The ductile to brittle transition temperature (DBTT) was observed to increase with an increasing silicon content. The Fe-15Al-2.8Si alloy was selected for more extensive testing due to the combination of high temperature strength and low temperature toughness due to the two phase {alpha} + DO{sub 3} structure. This investigation provided a framework for understanding the effects of silicon in powder processing and mechanical property behavior of Fe-Al-Si alloys.

  3. 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.

  4. Determining pathway structure-property relationships through experimentation and analytical frameworks.

    Science.gov (United States)

    Domach, M M; Majewski, R A

    1987-01-01

    A brief description of the information content of the experimental methods that are becoming increasingly useful for probing intracellular processes, a framework for interpreting observations, and an example that combines framework results and 13C NMR observations have been presented. Results in terms of structural criterion have been obtained that suggest that it may be possible to develop a glossary of structure-function heuristics. From the engineering point of view, such general work may also provide keys to system/subsystem modeling due to having some classic and nonclassic network properties mapped in advance. However, we note that approaches based solely on kinetics ignore physiochemical processes. A number of potential processes were mentioned earlier. Investigations of the importance of such processes, though, have been limited due to the dominance of in vitro enzyme kinetic and regulation work. Nonetheless, interesting proposals have been advanced by a limited number of workers, such as the suggestion that membrane-bound and soluble populations of enzymes with high and low activity, respectively, exist in eukaryotes (e.g., aldolase22) and the balanced attained between the two populations is an important regulatory mechanism. In an effort to contribute to the evaluation of physiochemical processes, our formalism was recently used to explore the logic of enzyme turnover number-enzyme amount distributions from the standpoint of minimizing excess enzymatic capacity (i.e., minimizing excess energy expenditure for protein biosynthesis) and the use of limited cytoplasmic solvation capacity (i.e., concentrated cytoplasm is water-limited; hence, maintaining the solubility of all constituents is difficult). PMID:3324850

  5. Quantitative structure-property relationships in boron nitrides: the 15N- and 11B chemical shifts.

    Science.gov (United States)

    Marian, C M; Gastreich, M

    2001-01-01

    Nuclear Magnetic Resonance (NMR) chemical shifts(delta) for elements in solids may often be approached by ab initio cluster calculations. We employ this technique to investigate the influence of structural alterations on the 15N and 11B chemical shifts in boron nitrides--in both hexagonal and cubic modifications. Within a given class of connectivity, i.e., three- or fourfold coordinated nitrogen, for the first time, an almost linear correlation between the 15N chemical shift and N-B bond lengths could be established. Also, the 11B shifts in hexagonal boron nitride correlate with the B-N bond distance; however, the effect is less pronounced. For the value of the chemical shift (CS), the decisive property is the average bond length at the atom in focus. Variations of CS are predominantly caused by changes in the paramagnetic deshielding. Further, second-nearest neighbor effects on the shieldings at 15N nuclei are quantified by subtraction schemes. The present work is closely related to the verification of models for amorphous high-demand Si/B/N ceramics. PMID:11407601

  6. 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.

  7. 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 (Nylon-6 and EVOH pair. The interdiffusion was followed by studying multilayer films of alternating Nylon-6 and EVOH layers that were coextruded with increasing number of layers. The AFM confirmed that the layers interdiffused with increasing number of layers and were forced to a homogeneous blend after several multiplications. The oxygen permeability of Nylon-6/EVOH multilayers was strongly affected by the amount of interdiffusion. The symmetry of the multilayers made it possible to model the composition profile through the layer thickness by application of Fick's law of diffusion. Subsequently, the oxygen permeability was directly related to the composition profile in each layer and changed as the interdiffusion proceeded. This methodology enabled the extraction of the mutual diffusion co-efficient, D, for the Nylon-6/EVOH system. The effect of comonomer content in EVOH on the mutual diffusion coefficient was also studied by comparing the kinetics of interdiffusion of Nylon-6 with two EVOHs containing 24 and 44 mole % ethylene. Chapter 3. Exciting new developments in polyolefin 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

  8. Dehalogenation of persistent halogenated organic compounds: A review of computational studies and quantitative structure-property relationships.

    Science.gov (United States)

    Luo, Jin; Hu, Jiwei; Wei, Xionghui; Fu, Liya; Li, Lingyun

    2015-07-01

    Dehalogenation is one of the highly important degradation reactions for halogenated organic compounds (HOCs) in the environment, which is also being developed as a potential type of the remediation technologies. In combination with the experimental results, intensive efforts have recently been devoted to the development of efficient theoretical methodologies (e.g. multi-scale simulation) to investigate the mechanisms for dehalogenation of HOCs. This review summarizes the structural characteristics of neutral molecules, anionic species and excited states of HOCs as well as their adsorption behavior on the surface of graphene and the Fe cluster. It discusses the key physiochemical properties (e.g. frontier orbital energies and thermodynamic properties) calculated at various levels of theory (e.g. semiempirical, ab initio, density functional theory (DFT) and the periodic DFT) as well as their connections to the reactivity and reaction pathway for the dehalogenation. This paper also reviews the advances in the linear and nonlinear quantitative structure-property relationship models for the dehalogenation kinetics of HOCs and in the mathematical modeling of the dehalogenation processes. Furthermore, prospects of further expansion and exploration of the current research fields are described in this article. PMID:25765260

  9. 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

  10. 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).

  11. 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.

  12. Oligomeric surfactants as novel type of amphiphiles : structure - property relationships and behaviour with additives

    OpenAIRE

    Wattebled, Laurent

    2006-01-01

    The properties of a series of well-defined new surfactant oligomers (dimers to tetramers)were examined. From a molecular point of view, these oligomeric surfactants consist of simple monomeric cationic surfactant fragments coupled via the hydrophilic ammonium chloride head groups by spacer groups (different in nature and length). Properties of these cationic surfactant oligomers in aqueous solution such as solubility, micellization and surface activity, micellar size and aggregation number we...

  13. Relationship between galactomannan structure and physicochemical properties of films produced thereof.

    Science.gov (United States)

    Dos Santos, V R F; Souza, B W S; Teixeira, J A; Vicente, A A; Cerqueira, M A

    2015-12-01

    In this work five sources of galactomannans, Adenanthera pavonina, Cyamopsis tetragonolobus, Caesalpinia pulcherrima, Ceratonia siliqua and Sophora japonica, presenting mannose/galactose ratios of 1.3, 1.7, 2.9, 3.4 and 5.6, respectively, were used to produce galactomannan-based films. These films were characterized in terms of: water vapour, oxygen and carbon dioxide permeabilities (WVP, O 2 P and CO 2 P); moisture content, water solubility, contact angle, elongation-at-break (EB), tensile strength (TS) and glass transition temperature (T g ). Results showed that films properties vary according to the galactomannan source (different galactose distribution) and their mannose/galactose ratio. Water affinity of mannan and galactose chains and the intermolecular interactions of mannose backbone should also be considered being factors that affect films' properties. This work has shown that knowing mannose/galactose ratio of galactomannans is possible to foresee galactomannan-based edible films properties. PMID:26604406

  14. Structure/property relationship in intergranular corrosion of archaeological silver artefacts.

    Czech Academy of Sciences Publication Activity Database

    Lej?ek, Pavel; Jäger, Aleš; Gärtnerová, Viera; Vaní?ková, J.; D?d, J.; Haloda, J.

    638-642, - (2009), 2852-2857. ISSN 0255-5476 R&D Projects: GA ?R GA106/08/0369; GA AV ?R KAN300100801 Institutional research plan: CEZ:AV0Z10100520 Keywords : anisotropy of grain boundary properties * archaeological silver artefacts * intergranular failure * selective corrosion * solute segregation * EBSD Subject RIV: BM - Solid Matter Physics ; Magnetism

  15. Structure-Activity Relationships of Antimicrobial and Lipoteichoic Acid-Sequestering Properties in Polyamine Sulfonamides ?

    OpenAIRE

    Warshakoon, Hemamali J.; Burns, Mark R.; David, Sunil A.

    2008-01-01

    We have recently confirmed that lipoteichoic acid (LTA), a major constituent of the gram-positive bacterial surface, is the endotoxin of gram-positive bacteria that induces proinflammatory molecules in a Toll-like receptor 2 (TLR2)-dependent manner. LTA is an anionic amphipath whose physicochemical properties are similar to those of lipopolysaccharide (LPS), which is found on the outer leaflet of the outer membranes of gram-negative organisms. Hypothesizing that compounds that sequester LPS c...

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

    Energy Technology Data Exchange (ETDEWEB)

    Verevkin, Sergey P., E-mail: sergey.verevkin@uni-rostock.de [Faculty of Interdisciplinary Research, Department “Life, Light and Matter”, University of Rostock (Germany); Department of Physical Chemistry, University of Rostock, Dr-Lorenz-Weg. 1, 18059 Rostock (Germany); Zaitsau, Dzmitry H.; Emel’yanenko, Vladimir N.; Ralys, Ricardas V.; Yermalayeu, Andrei V. [Department of Physical Chemistry, University of Rostock, Dr-Lorenz-Weg. 1, 18059 Rostock (Germany); Schick, Christoph [Department of Physics, University of Rostock, Wismarsche Str. 43-45, 18057 Rostock (Germany)

    2013-06-20

    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 [C{sub n}mim][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.

  17. Investigations of the processing-structure-property relationships of selected semicrystalline polymers

    Science.gov (United States)

    Johnson, Matthew Brian

    2000-10-01

    An investigation was carried out on a three stage method (extrusion/annealing/uniaxial-stretching) (MEAUS) utilized to produce semicrystalline polymeric microporous membranes. The two semicrystalline polymers studied were selected based on a set-of-prerequisites proposed for the formation of highly porous membranes via the method in question. The prerequisites included "fast" crystallization kinetics, presence of an alphac relaxation, ability to form a planar stacked lamellar morphology with a "good" crystalline orientation upon melt-extrusion, and rapid heat transfer of the film during extrusion. The first polymer was isotactic poly(4-methyl-1-pentene) (PMP), and the second was polyoxymethylene (POM). Three PMP resins were studied, which differed in weight average molecular weight. Three POM resins were also investigated where two of resins were characterized by relatively narrow molecular weight distributions (MWD) ca 2 while the third POM resin possessed a MWD ca 5.9. The melt-extruded film morphologies and orientation values were a consequence of the melt-relaxation times as a result of the resin characteristics and/or the melt-extrusion conditions. Following the extrusion stage, the effect of annealing (second stage) on film properties was investigated. The annealing variables investigated included the temperature, time, and level of extension applied during annealing. The annealed films were then subjected to the uniaxially stretching stage (third stage) consisting of a cold and hot step, respectively, where deformation was along the extrusion direction. The variables of interest included the cold and hot stretch temperature and extension level. It was found that starting precursor morphology and orientation, annealing conditions, and stretching variables impact the final film microporous morphology and permeability. Additionally, the proposed prerequisites were verified in both the PMP and POM film series. In addition to the MEAUS study, a comprehensive investigation was conducted of the optical properties of blown and cast films made from conventional Ziegler-Natta catalyzed linear low density polyethylene (LLDPE) as well as metallocene-catalyzed LLDPE resins. From this work, it was determined that in PE blown and cast films made using conventional processing conditions, the optical haze properties are adversely affected due to enhanced surface roughness caused by the formation of spherulitic-like superstructures in polymer melts that possess fast relaxing and low melt elasticity rheological characteristics. This optical property study was also published in J. Appl. Polym. Sci., 77(13), 2845, (2000).

  18. New eco-friendly random copolyesters based on poly(propylene cyclohexanedicarboxylate: Structure-properties relationships

    Directory of Open Access Journals (Sweden)

    L. Genovese

    2015-11-01

    Full Text Available A series of novel random copolymers of poly(propylene 1,4-cyclohexanedicarboxylate (PPCE containing neo -pentyl glycol sub-unit (P(PCExNCEy were synthesized and characterized in terms of molecular and solid-state properties. In addition, biodegradability studies in compost have been conducted. The copolymers displayed a high and similar thermal stability with respect to PPCE. At room temperature, all the copolymers appeared as semicrystalline materials: the main effect of copolymerization was a lowering of crystallinity degree (?c and a decrease of the melting temperature compared to the parent homopolymer. In particular, Wide Angle X-Ray diffraction (WAXD measurements indicated that P(PCExNCEy copolymers are characterized by cocrystallization, PNCE counits cocrystallizing in PPCE crystalline phase. Final properties and biodegradation rate of the materials under study were strictly dependent on copolymer composition and ?c. As a matter of fact, the elastic modulus and the elongation at break decreased and increased, respectively, as neopentyl glycol cyclohexanedicarboxylate (NCE unit content was increased. The presence of a rigid-amorphous phase was evidenced by means of Dynamic Mechanical Thermal Analysis (DMTA analysis in all the samples under investigation. Lastly, the biodegradation rate of P(PCExNCEy copolymers was found to slightly increase with the increasing of NCE molar content.

  19. Novel indole and azaindole (pyrrolopyridine) cannabinoid (CB) receptor agonists: design, synthesis, structure-activity relationships, physicochemical properties and biological activity.

    Science.gov (United States)

    Blaazer, Antoni R; Lange, Jos H M; van der Neut, Martina A W; Mulder, Arie; den Boon, Femke S; Werkman, Taco R; Kruse, Chris G; Wadman, Wytse J

    2011-10-01

    The discovery, synthesis and structure-activity relationship (SAR) of a novel series of cannabinoid 1 (CB(1)) and cannabinoid 2 (CB(2)) receptor ligands are reported. Based on the aminoalkylindole class of cannabinoid receptor agonists, a biphenyl moiety was introduced as novel lipophilic indole 3-acyl substituent in 11-16. Furthermore, the 3-carbonyl tether was replaced with a carboxamide linker in 17-20 and the azaindole (pyrrolopyridine) nucleus was designed as indole bioisostere with improved physicochemical properties in 21-25. Through these SAR efforts, several high affinity CB(1)/CB(2) dual cannabinoid receptor ligands were identified. Indole-3-carboxamide 17 displayed single-digit nanomolar affinity and ~80 fold selectivity for CB(1) over the CB(2) receptor. The azaindoles displayed substantially improved physicochemical properties (lipophilicity; aqueous solubility). Azaindole 21 elicited potent cannabinoid activity. Cannabinoid receptor agonists 17 and 21 potently modulated excitatory synaptic transmission in an acute rat brain slice model of cannabinoid receptor-modulated neurotransmission. PMID:21885167

  20. Barium titanate/polyester resin nanocomposites: Development, structure-properties relationship and energy storage capability

    OpenAIRE

    I. A. Asimakopoulos; G. C. Psarras; L. Zoumpoulakis

    2014-01-01

    Nanocomposite materials based on two different types of polyester matrix (a commercial type and a laboratory produced one) with embedded barium titanate nano-particles were developed and characterized. Structural and morphological characteristics of the produced composite specimens were studied via X-ray diffraction, Fourier transformation infra red spectroscopy, and scanning electron microscopy. Thermal, mechanical and electrical performance was examined via differential scanning calorimetry...

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

    OpenAIRE

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

    2006-01-01

    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 ...

  2. 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.

  3. 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

  4. 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)

  5. Structure-property relationships of carboxymethyl hydroxypropyl guar gum in water and a hyperentanglement parameter.

    Science.gov (United States)

    Szopinski, Daniel; Kulicke, Werner-Michael; Luinstra, Gerrit A

    2015-03-30

    The viscoelastic properties of carboxymethyl hydroxypropyl guar gum (CMHPG) in aqueous solution were determined as function of concentration and of molecular weight, using SEC/MALLS/dRI and viscometry. The chain is more rigid as in native guar as was deduced from the molecular parameter in dilute solution. Superstructures are formed in moderately concentrated solutions as is shown from the comparison of steady state shear and small amplitude oscillatory shear (SAOS) experiments. The shear rate dependent viscosity of CMHPG can satisfactorily be described by the Carreau-Yasuda model with the rheological parameters (?0, ?0, n, b) obtained from the evaluation of viscosity data. A quantitative hyperentanglement parameter is introduced to account for the differences in responses in shear and SAOS experiments. PMID:25563956

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

    DEFF Research Database (Denmark)

    Langholm Jensen, Jesper; 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.

  7. Quantitative structure-property relationships of potentially bioactive fluoro phospho-silicate glasses.

    Science.gov (United States)

    Lusvardi, G; Malavasi, G; Tarsitano, F; Menabue, L; Menziani, M C; Pedone, A

    2009-07-30

    In this work, the glass transition temperature and chemical durability of bioactive phospho-silicate glasses were experimentally determined and correlated to the structural descriptor Fnet derived from classical molecular dynamics simulations. The replacement of CaF2 for Na2O in the parent glass 45S5 enhances both chemical durability and density, while the replacement of CaF2 for CaO lowers chemical durability. The proposed descriptor, Fnet, provides satisfactorily correlations with glass transition temperature and chemical durability over a wide range of compositions. PMID:19572677

  8. 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.

  9. 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.

  10. QUANTITATIVE STRUCTURE–PROPERTY RELATIONSHIP (QSPR) STUDY OF KOVATS RETENTION INDICES OF SOME OF ADAMANTANE DERIVATIVES BYTHE GENETIC ALGORITHM AND MULTIPLE LINEAR REGRESSION (GA-MLR) METHOD

    OpenAIRE

    Z. Bayat; M. Fakoor Yazdan Abad

    2011-01-01

    A quantitative structure–property relationship (QSPR) study was performed to develop models those relate the structures of 65 Kovats retention index (RI) of adamantane derivatives. Molecular descriptors derived solely from 3D structures of the molecular compounds. A genetic algorithm was also applied as a variable selection tool in QSPR analysis. The models were constructed using 52 molecules as training set, and predictive ability tested using 13 compounds. Modeling of RI of Adamantane deriv...

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

    Directory of Open Access Journals (Sweden)

    Pereira Fabiano V.

    2006-01-01

    Full Text Available 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.

  12. Composition-structure-property-performance relationship inMn-substituted LiMn2O4

    Energy Technology Data Exchange (ETDEWEB)

    Horne, Craig R.; Richardson, Thomas J.; Gee, B.; Tucker, Mike; Grush, Melissa M.; Bergmann, Uwe; Striebel, Kathryn A.; Cramer, StephenP.; Reimer, Jeffrey A.; Cairns, Elton J.

    2001-03-09

    The spinel LiMn{sub 2}O{sub 4} has been extensively studied as a positive electrode active material in lithium rechargeable batteries. Partial substitution of Mn by another metal has also been the subject of recent study in an effort to improve the cycling performance. In general, the literature has shown that Mn substitution results in improved cycling stability at the expense of capacity (1,2). Resistance to the formation of tetragonal phase upon lithiation of the starting spinel (via a higher nominal Mn oxidation state in the substituted spinel) has been suggested as a mechanism for the improved performance. The degree of substitution is an important factor to optimize in order to minimize capacity loss and costs. The spectroscopic investigations on LiMn{sub 2}O{sub 4} described in the previous paper (LixMn2O4) confirmed that the cooperative Jahn-Teller effect (CJTE) from the [Mn{sup 3+}O{sub 6}] octahedra is the mechanism for the cubic to tetragonal phase transformation. The driving force for the CJTE is based upon the electronic structure, therefore changes in electronic structure should lead to changes in the phase behavior. The fact that the LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} does not form tetragonal phase upon discharging (FUJI3, MUCK?), unlike the 100% Mn{sup 4+} spinel Li{sub 4}Mn{sub 5}O{sub 12} (THAC5), led to the hypothesis that an increased degree of covalency as a source for the behavior. An increased covalence would remove the driving force for the transformation, the increased electronic stability achieved in tetragonally-distorted [Mn{sup 3+}O{sub 6}] octahedra, due to a change in electron density and widening of the Mn 3d bands. The STH field is dependent upon the amount of unpaired spin density transferred between the magnetic (transition-metal) and diamagnetic ions through an intermittent oxygen ion, attributable to overlap and electron transfer effects. Therefore, the magnitude of the STH coupling constant reflects the degree of covalency (GESC, HUAN). In the case of LiMn{sub 2-y}Me{sub y}O{sub 4}, the STH coupling constant characterizes the amount of unpaired spin density transferred to the Li{sup +} from the Mn, Co, or Ni. Similarly, the La/Lb ratio of the Mn L-XES is sensitive to the amount of electron density at the Mn site as a higher ratio indicates that the Mn 3d{sub 5/2} level is more populated (GRUS1). An investigation into the effects of Mn-substitution on the electronic structure along with the ramifications to the phase behavior upon changing lithium content was carried out. To accomplish this, a set of LiMn{sub 2-y}Me{sub y}O{sub 4} with Me = Li, Co, or Ni over a range of y were synthesized, characterized, and subjected to changes in lithium content by various techniques.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fatyeyeva, K., E-mail: kateryna.fatyeyeva@univ-rouen.fr [Institute of Bioorganic Chemistry and Petrochemistry of National Academy of Science of Ukraine, 50 Kharkivske shose, Kyiv 02160 (Ukraine); Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087, Universite du Maine, Av. Olivier Messiaen, 72085 Le Mans cedex 9 (France); Laboratoire Polymeres, Biopolymeres et Surfaces, UMR 6270 and FR 3038 CNRS, Universite de Rouen, Bd. Maurice de Broglie, 76821 Mont Saint Aignan cedex (France); Pud, A.A. [Institute of Bioorganic Chemistry and Petrochemistry of National Academy of Science of Ukraine, 50 Kharkivske shose, Kyiv 02160 (Ukraine); Bardeau, J.-F.; Tabellout, M. [Laboratoire de Physique de l' Etat Condense, UMR CNRS 6087, Universite du Maine, Av. Olivier Messiaen, 72085 Le Mans cedex 9 (France)

    2011-10-17

    Highlights: {yields} Synthesis of surface conducting polymers based on aliphatic polyamides and polyaniline. {yields} The study revealed the layered structure of the surface conductive composites. {yields} Different dielectric relaxation processes were found as a function of doping agent and polyaniline oxidation state. {yields} Conductivity value (10{sup -4}-10{sup -11} S cm{sup -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.

  14. Barium titanate/polyester resin nanocomposites: Development, structure-properties relationship and energy storage capability

    Directory of Open Access Journals (Sweden)

    I. A. Asimakopoulos

    2014-09-01

    Full Text Available Nanocomposite materials based on two different types of polyester matrix (a commercial type and a laboratory produced one with embedded barium titanate nano-particles were developed and characterized. Structural and morphological characteristics of the produced composite specimens were studied via X-ray diffraction, Fourier transformation infra red spectroscopy, and scanning electron microscopy. Thermal, mechanical and electrical performance was examined via differential scanning calorimetry, bending and shear strength tests, and broadband dielectric spectroscopy, respectively. Mechanical strength appears to reduce with the increase of filler content. Commercial polyester’s composites exhibit brittle behaviour, while laboratory polyester’s composites exhibit an elastomeric performance. Dielectric data reveal the presence of four relaxation processes, which are attributed to motion of small parts of the polymer chain (?-mode, re-arrangement of polar side groups (?-mode, glass to rubber transition of the polymer matrix (?-mode and Interfacial Polarization between the systems’ constituents. Finally, the energy storing efficiency of the systems was examined by calculating the density of energy.

  15. A density functional theory study of structure-property relationships for Pt-Ni alloy catalysts

    Science.gov (United States)

    Cao, Liang; Mueller, Tim

    2013-03-01

    The ORR (Oxygen Reduction Reaction) is an important reaction in devices such as metal-air batteries and PEMFCs (Polymer Electrolyte Membrane fuel cells). Pure Pt is one of the most successful electrode catalysts for this key reaction. However, due to its expense, numerous efforts have been made to find a new catalysis system based on Pt bimetallic alloys, in which Pt is partially replaced by less expensive metals, such as Ni, Co and Fe. Experimental and theoretical works have shown that Pt3Ni alloys have a higher ORR activity than pure Pt. In order to investigate the enhanced catalytic activity, cluster expansions corresponding to a simplified 9-layer Pt-Ni slab model are built to accurately and quickly predict the energies of surfaces as a function of atomic order. With the help of this model, we can study systematically the atomic structure and the surface geometry of Pt3Ni surface system at a variety of temperature and chemical environments, and we can calculate the adsorption binding energies of O, OH and H on both equilibrium and non-equilibrium Pt-Ni(111) surfaces. Also, we can investigate the effects of off-stoichiometry on surface by searching for stable ground states under different concentrations.

  16. Structure-property relationships in main-chain liquid crystalline networks

    Science.gov (United States)

    Burke, Kelly Anne

    Main-chain liquid crystalline networks were prepared from mesogenic dienes using two different synthetic routes. First, main-chain liquid crystalline copolymers were synthesized by polymerizing a mesogen with a nonmesogenic comonomer using acyclic diene metathesis (ADMET) chemistry. The resulting polymers form nematic phases, with composition dictating the glass transition and isotropization temperatures. Free-radical crosslinking through the unsaturated bonds in the polymer was demonstrated for a selected composition to lead to an elastomeric network. This two step process was employed to control the polymer properties before crosslinking and serves as a viable route to tailored nematic networks for applications as anisotropic adhesives. Liquid crystalline elastomers (LCEs) were prepared using a second synthetic route that employed hydrosilylation chemistry to react the mesogens with hydrideterminated poly(dimethylsiloxane) and a vinyl crosslinker. The resulting LCEs formed a smectic-C phase with transition temperatures that depend on mesogen composition. The mesogens impart two distinct active behaviors to the elastomers. The first of these is actuation, the reversible extension and contraction of the polymer when cooled and heated, respectively, through the mesogen isotropization transition. Actuation is dependent on the crosslink density of the material and can cause the samples to elongate as much as 30% under tensile load. The second active behavior is shape memory, the ability to fix a temporary deformation and later recover the equilibrium shape by heating. The LCEs have excellent shape memory fixing and recovery ratios, both of which generally exceeded 95%. The ability of a soft network to fix strains above room temperature is unusual and was investigated using a combination of thermal analysis, mechanical testing, and wide angle x-ray scattering, where it was found that strain is fixed by freezing the mesogens within the smectic layers. The LCE's low modulus was exploited by reversible embossing, the localization of a temporary topography onto the LCE using shape memory. A microscale embossed topography was stable until erased by heating to recover the LCE's flat, permanent shape. Possible applications of these LCEs include artificial muscles, smart shear-based actuators, and active substrates.

  17. Structure-composition-property relationships in 5xxx series aluminum alloys

    Science.gov (United States)

    Unocic, Kinga A.

    Al-Mg alloys are well suited for marine applications due to their low density, ease of fabrication, structural durability, and most notably resistance to corrosion. The purpose of this study is to investigate the effects of alloying additions, mechanical processing and heat treatments on the development of grain boundary phases that have an effect on intergranular corrosion (IGC). Cu, Zn, and Si modified compositions of AA5083 were produced that were subjected to a low and high degree of cold work and various heat treatments. ASTM G67 (NAMLT) intergranular corrosion testing and detailed microstructural characterization for various alloys was carried out. An optimal composition and processing condition that yielded the best intergranular corrosion resistant material was identified based on the ASTM G67 test screening. Further, the outstanding modified AA5083 was selected for further microstructural analysis. This particular alloy with has a magnesium level high enough to make it susceptible to intergranular corrosion is very resistant to IGC. It was found that development of the appropriate sub-structure with some Cu, Si and Zn resulted in a material very resistant to IGC. Formation of many sinks, provided by sub-boundaries, within microstructure is very beneficial since it produces a relatively uniform distribution of Mg in the grain interiors, and this can suppress sensitization of this alloy very successfully. This is a very promising rote for the production of high-strength, and corrosion resistant aluminum alloys. Additionally in this study, TEM sample preparation become very crucial step in grain boundary phase investigation. Focus Ion Beam (FIB) milling was used as a primary TEM sample preparation technique because it enables to extract the samples from desired and very specific locations without dissolving grain boundary phases as it was in conventional electropolishing method. However, other issues specifically relevant to FIB milling of aluminum alloys related to Ga accumulation were discovered, that produce significant microstructural artifacts. It is well known that liquid gallium can cause Liquid Metal Embitterment (LME) aluminum alloys, and gallium readily penetrates aluminum grain boundaries. Low energy Ar ion nanomilling is potentially quite effective at removing gallium from the external and internal surfaces of aluminum thin foils, but can still leave persistent artifacts. Al-Mg alloys can be also susceptible to localized corrosion such as pitting corrosion in the presence of chloride ions. In this study the phases responsible for this type of corrosion were identified. ASSET (ASTM G66) test was used to determine the influence of heat-treatment on pitting corrosion on various modified AA5083 alloys. Additionally, potentiodynamic polarization as well as potentiostatic measurements in conjunction with SEM analysis were carried out to obtain pitting potential (Epit) and to determine the location of metastable pit initiation, respectively.

  18. 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.

  19. Structure-to-property relationships in fuel cell catalyst supports: Correlation of surface chemistry and morphology with oxidation resistance of carbon blacks

    Science.gov (United States)

    Artyushkova, Kateryna; Pylypenko, Svitlana; Dowlapalli, Madhu; Atanassov, Plamen

    2012-09-01

    Linking durability of carbon blacks, expressed as their oxidation resistance, used in PEMFCs as catalyst supports, with their chemistry and morphology is an important task towards designing carbon blacks with desired properties. Structure-to-property relationship between surface chemistry determined by X-ray photoelectron spectroscopy (XPS), morphological structure determined by digital image processing of scanning electron microscopy (SEM) images, physical properties, and electrochemical corrosion behavior determined in an air-breathing gas-diffusion electrode is studied for several un-altered and several modified carbon blacks. We are showing that surface chemistry, graphitic content and certain physical characteristics such as Brunauer-Emmett-Teller (BET) surface area and pore volume, determined by nitrogen adsorptions are not sufficient to explain high corrosion instability of types of carbon blacks. Inclusion of morphological characteristics, such as roughness, texture and shape parameters provide for more inclusive description and therefore more complete structure-to-property correlations of corrosion behavior of carbon blacks. This paper presents the first direct statistically-derived structure-to-property relationship, developed by multivariate analysis (MVA) that links chemical and physical structural properties of the carbon blacks to their critical properties as supports for PEMFC catalysts. We have found that balance between electrocatalytic activity and high resistance towards oxidation and corrosion is achieved by balance between amount of graphitic content and surface oxide coverage, smaller overall roughness and, finally, larger amount of big elongated and loose, and, hypothetically, more hydrophobic pores.

  20. 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.

  1. Quantitative structure-property relationship studies on electrochemical degradation of substituted phenols using a support vector machine.

    Science.gov (United States)

    Yuan, S; Xiao, M; Zheng, G; Tian, M; Lu, X

    2006-10-01

    A quantitative structure-property relationship (QSPR) model has been developed for the electrochemical degradation of substituted phenols using a support vector machine (SVM). Thirty descriptors, including quantum chemical parameters, steric effect descriptors and half wave potential (E1/2), were used for describing twelve substituted phenols, including mono- and multi-substituent phenols. A leave-one-out (LOO) cross validation procedure resulted in the selection of three descriptors, the total of electron and nuclear energies of the two-center terms for the carbon-chlorine or carbon-nitrogen bond (TE2), the net atomic charges on the chlorine or nitrogen (qx), and the largest negative atomic charge on an atom (q-). The model based on SVM yielded a Q2 value of 0.892, indicating a high predictive ability. Compared with models developed with partial least squares (PLS) and multiple linear regression (MLR), where Q2 were 0.804 and 0.799 respectively, SVM showed higher performances. PMID:17050187

  2. Structure-behavior-property relationship study of surfactants as foam stabilizers explored by experimental and molecular simulation approaches.

    Science.gov (United States)

    Hu, Xiaoying; Li, Ying; He, Xiujuan; Li, Chunxiu; Li, Zhengquan; Cao, Xulong; Xin, Xia; Somasundaran, P

    2012-01-12

    A multiscale stability study of foams stabilized by sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium polyoxyethylene alkylether sulfate (AES) was conducted, to investigate the relationship of surfactant molecular behavior and interfacial monolayer configuration of foam film to the foam film properties. Molecular dynamic (MD) simulations using a full-atom model was utilized to explore the microscopic features of the air/liquid interface layer. Several parameters such as the distribution of surfactant head groups and the order degree of surfactant hydrophobic tails were used to describe the molecular adsorption behavior. The effect of molecular structure on the nature of the foam film and the impact on the dynamic stability of wet foam is discussed. In the experimental evaluation, the SDBS foam films manifest strong stiffness and low viscoelasticity as shown by the interfacial shear rheology determination as well as texture analyzer (TA) measurement results, which agree very well with the array behavior of SDBS molecules at the air/water interface as described by the simulation results and is identified to be the reason for the poor dynamic stability. Comparing the molecular structure of SDS, SDBS, and AES, the special contributions of the linking groups such as the O atom, the phenyl group, and the EO (oxyethyl) chain to the interfacial array behavior of surfactants were characterized. It is concluded that microhardness of the foam film enhanced by rigid linking groups favors static foam stability but decreases the dynamic foam stability, while viscoelasticity of the foam film enhanced by soft linking groups increases the dynamic foam stability. PMID:22136447

  3. Relationships between Structural and Photo-induced Properties of the Thin Sol-gel TiO2 Layers.

    Czech Academy of Sciences Publication Activity Database

    Morozová, Magdalena; Kluso?, Petr; Dzik, P.; Veselý, M.; Baudys, M.; Krýsa, J.; Šolcová, Olga

    Prague : Institute of Chemical Technology, 2013 - (Krýsa, J.), s. 161 ISBN 978-80-7080-854-2. [International Conference on Semiconductor Photochemistry /4./. Prague (CZ), 23.06.2013-27.06.2013] R&D Projects: GA TA ?R TA01020804; GA TA ?R TA03010548 Institutional support: RVO:67985858 Keywords : thin TiO2 layers * structural properties * photo-induced properties Subject RIV: CI - Industrial Chemistry, Chemical Engineering http://www.sp4-prague.cz/

  4. 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.

  5. 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.

  6. Comprehensive Study of Third-Order Nonlinear Tungstates: Relationship between Structural and Vibrational Properties in Raman Shifters

    Science.gov (United States)

    Gallucci, E.; Goutaudier, C.; Bourgeois, F.; Boulon, G.; Cohen-Adad, M. Th.

    2002-02-01

    Although tungstates are now well known as laser Raman shifters, their physicochemical properties (especially the vibrational ones) were not often studied. We have carried out a comprehensive and systematic study of tungstate Raman spectra, thanks to which, structural and vibrational properties could be correlated. It was shown that the Raman scattering characteristics of these compounds are directed by simple physical chemistry parameters. They change logically with easy interpolation. The optimization of the search for tungstates as new efficient Raman shifters was realized through a figure of merit: a map where the Raman frequency is described versus a normalized parameter representative of the Raman gain.

  7. Relationship between the physical and structural properties of NbzSiyNx thin films deposited by dc reactive magnetron sputtering

    International Nuclear Information System (INIS)

    The optical and electrical properties of NbzSiyNx thin films deposited by dc reactive magnetron sputtering have been investigated as a function of the Si content (CSi). Optical properties were studied by both specular reflectivity and spectroscopic ellipsometry. Electrical resistivity was measured by the van der Pauw method at room temperature and as a function of the temperature down to 10 K. Both the optical and electrical properties of NbzSiyNx films are closely related with the chemical composition and microstructure evolution caused by Si addition. For CSi up to 4 at. % the Si atoms are soluble in the lattice of the NbN crystallites. In this compositional regime, the optical and electrical properties show little dependence on the Si content. Between 4 and 7 at. % the surplus of Si atoms segregates at the grain boundaries, builds an insulating SiNx layer, and originates important modifications in the optical and electrical properties of these films. Further increase of CSi leads to the formation of nanocomposite structures. The electrical properties of these films are well described by the grain-boundary scattering model with low probability for electrons to cross the grain boundary. The appearance of the intragranular-insulating SiNx layer and the reduction of the grain size are noticed in the dielectric function mainly as a strong damping of the plasma oscillation

  8. Branched isomeric 1,2,3-triazolium-based ionic liquids: new insight into structure-property relationships.

    Science.gov (United States)

    Lartey, M; Meyer-Ilse, J; Watkins, J D; Roth, E A; Bowser, S; Kusuma, V A; Damodaran, K; Zhou, X; Haranczyk, M; Albenze, E; Luebke, D R; Hopkinson, D; Kortright, J B; Nulwala, H B

    2015-11-28

    A series of four isomeric 1,2,3-triazolium-based ionic liquids (ILs) with vary degree of branching were synthesized and characterized to investigate the effect of ion branching on thermal and physical properties of the resulting IL. It was found that increased branching led to a higher ionicity and higher viscosity. The thermal properties were also altered significantly and spectral changes in the near edge X-ray absorption fine structure (NEXAFS) spectra show that branching affects intermolecular interaction. While the ionicity and viscosity varying linearly with branching, the MDSC and NEXAFS measurements show that the cation shape has a stronger influence on the melting temperature and absorptive properties than the number of branched alkyl substituents. PMID:26486091

  9. 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.

  10. 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

  11. 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, 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

  12. Supramolecular Dimerization and [2 + 2] Photocycloaddition Reactions of Crown Ether Styryl Dyes Containing a Tethered Ammonium Group: Structure-Property Relationships.

    Science.gov (United States)

    Ushakov, Evgeny N; Vedernikov, Artem I; Lobova, Natalia A; Dmitrieva, Svetlana N; Kuz'mina, Lyudmila G; Moiseeva, Anna A; Howard, Judith A K; Alfimov, Michael V; Gromov, Sergey P

    2015-12-31

    Molecular self-assembly is an effective strategy for controlling the [2 + 2] photocycloaddition reaction of olefins. The geometrical properties of supramolecular assemblies are proven to have a critical effect on the efficiency and selectivity of this photoreaction both in the solid state and in solution, but the role of other factors remains poorly understood. Convenient supramolecular systems to study the structure-property relationships are pseudocyclic dimers spontaneously formed by styryl dyes containing a crown ether moiety and a remote ammonium group. New dyes of this type were synthesized to investigate the effects of structural and electronic factors on the quantitative characteristics of supramolecular dimerization and [2 + 2] photocycloaddition in solution. Variable structural parameters for the styryl dyes were the size and structure of macrocyclic moiety, the nature of heteroaromatic residue, and the length of the ammonioalkyl group attached to this residue. Quantum chemical calculations of the pseudocyclic dimers were performed in order to interpret the relationships between the structure of the ammonium dyes and the efficiency of the supramolecular photoreaction. One of the dimeric complexes was obtained in the crystalline state and studied by X-ray diffraction. The results obtained demonstrate that the photocycloaddition in the pseudocyclic dimers can be dramatically affected by the electronic structure of the styryl moieties, as dependent on the electron-donating ability of the substituents on the benzene ring, and by the conformational flexibility of the pseudocycle, which determines the mobility of the olefinic bonds. The significance of electronic factors is highlighted by the fact that the photocycloaddition quantum yield in geometrically similar dimeric structures varies from ?10(-4) to 0.38. The latter value is unusually high for olefins in solution. PMID:26650887

  13. 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.

  14. 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

  15. A relationship between structural and electronic order-disorder effects and optical properties in crystalline TiO2 nanomaterials.

    Science.gov (United States)

    Silva Junior, E; La Porta, F A; Liu, M S; Andrés, J; Varela, J A; Longo, E

    2015-02-21

    The focus of this paper is on the analysis of the structural and electronic order-disorder effects at long, medium and short ranges of titanium dioxide (TiO2) nanoparticles synthesized by the sol-gel process followed by the microwave-assisted solvothermal (MAS) method at low temperatures and short reaction times. X-ray diffraction (XRD), Rietveld refinement, micro-Raman (MR) spectroscopy, transmission electron microscopy (TEM) and X-ray spectroscopy (EDX) were used to characterize the TiO2 nanoparticles. Optical properties were investigated by ultraviolet-visible (UV-vis) and photoluminescence (PL) measurements performed at room temperature. XRD and Rietveld refinement confirmed the presence of the anatase and brookite phases; nonetheless anatase is the major phase. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of only Ti(4+) but the nonstoichiometry revealed that TiO2 NPs contain defects assigned to oxygen vacancies that lead to structural and electronic order-disorder effects observed by band gap narrowing and PL wide band emission. These intermediary energy levels (shallow and deep levels) created within the band gap act as acceptors/donors of electrons and recombination centers. The oxygen vacancies (VO(x), VO? and VO??) responsible by degree of structural order-disorder are related to distortions (tilts) on the [TiO6] octahedron and changes in the bond lengths and bond angles between oxygen and titanium atoms that gave rise to new species of cluster makers such as [TiO6]', [TiO5·VO(x)], [TiO5·VO?] and [TiO5·VO??]. This structural transformation is consistent with a redistribution of electron density from highly ordered [TiO6](x) clusters which form distorted [TiO6]' as well as complex [TiO5·VO(x)], [TiO5·VO?] and [TiO5·VO??] clusters assigned to oxygen vacancies which were understood as displacements in the oxygen atoms' position in the bond lengths (Ti-O). PMID:25579134

  16. The mechanical properties of human adipose tissues and their relationships to the structure and composition of the extracellular matrix.

    Science.gov (United States)

    Alkhouli, Nadia; Mansfield, Jessica; Green, Ellen; Bell, James; Knight, Beatrice; Liversedge, Neil; Tham, Ji Chung; Welbourn, Richard; Shore, Angela C; Kos, Katarina; Winlove, C Peter

    2013-12-01

    Adipose tissue (AT) expansion in obesity is characterized by cellular growth and continuous extracellular matrix (ECM) remodeling with increased fibrillar collagen deposition. It is hypothesized that the matrix can inhibit cellular expansion and lipid storage. Therefore, it is important to fully characterize the ECM's biomechanical properties and its interactions with cells. In this study, we characterize and compare the mechanical properties of human subcutaneous and omental tissues, which have different physiological functions. AT was obtained from 44 subjects undergoing surgery. Force/extension and stress/relaxation data were obtained. The effects of osmotic challenge were measured to investigate the cellular contribution to tissue mechanics. Tissue structure and its response to tensile strain were determined using nonlinear microscopy. AT showed nonlinear stress/strain characteristics of up to a 30% strain. Comparing paired subcutaneous and omental samples (n = 19), the moduli were lower in subcutaneous: initial 1.6 ± 0.8 (means ± SD) and 2.9 ± 1.5 kPa (P = 0.001), final 11.7 ± 6.4 and 32 ± 15.6 kPa (P energy dissipation density was lower in subcutaneous AT (n = 13): 0.1 ± 0.1 and 0.3 ± 0.2 kPa, respectively (P = 0.006). Stress/relaxation followed a two-exponential time course. When the incubation medium was exchanged for deionized water in specimens held at 30% strain, force decreased by 31%, and the final modulus increased significantly. Nonlinear microscopy revealed collagen and elastin networks in close proximity to adipocytes and a larger-scale network of larger fiber bundles. There was considerable microscale heterogeneity in the response to strain in both cells and matrix fibers. These results suggest that subcutaneous AT has greater capacity for expansion and recovery from mechanical deformation than omental AT. PMID:24105412

  17. 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 (R2) for MLR model were 0.22 and 0.99 for the prediction set log Po/w

  18. 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.

  19. 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

  20. 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.)

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

    OpenAIRE

    Singh, S.K.; Sangita Saini; Bharat Verma; Mishra, D. N.

    2009-01-01

    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 ar...

  2. Quantitative structure-property relationship modeling of water-to-wet butyl acetate partition coefficient of 76 organic solutes using multiple linear regression and artificial neural network.

    Science.gov (United States)

    Dashtbozorgi, Zahra; Golmohammadi, Hassan

    2010-12-01

    The main aim of this study was the development of a quantitative structure-property relationship method using an artificial neural network (ANN) for predicting the water-to-wet butyl acetate partition coefficients of organic solutes. As a first step, a genetic algorithm-multiple linear regression model was developed; the descriptors appearing in this model were considered as inputs for the ANN. These descriptors are principal moment of inertia C (I(C)), area-weighted surface charge of hydrogen-bonding donor atoms (HACA-2), Kier and Hall index (order 2) ((2)?), Balaban index (J), minimum bond order of a C atom (P(C)) and relative negative-charged SA (RNCS). Then a 6-4-1 neural network was generated for the prediction of water-to-wet butyl acetate partition coefficients of 76 organic solutes. By comparing the results obtained from multiple linear regression and ANN models, it can be seen that statistical parameters (Fisher ratio, correlation coefficient and standard error) of the ANN model are better than that regression model, which indicates that nonlinear model can simulate the relationship between the structural descriptors and the partition coefficients of the investigated molecules more accurately. PMID:21082679

  3. Quantitative structure-property relationship study on first reduction and oxidation potentials of donor-substituted phenylquinolinylethynes and phenylisoquinolinylethynes: Quantum chemical investigation

    International Nuclear Information System (INIS)

    The relationship between the chemical structure, first reduction and oxidation potentials of 30 Phenylquinolinylethyne (PhQE), and Phenylisoquinolinylethyne (PhIE) derivative compounds has been elucidated employing ab initio calculations. Quantum chemical calculations (HF/6-31G) were carried out to obtain: the optimized geometry, energy levels, quantum chemical indices, charges and dipole moments of these compounds. The quantitative structure-property relationship (QSPR) of PhQE and PhIE was studied for the first reduction (Ered), and the first oxidation (Eox) potentials. The genetic algorithm (GA) was applied to select the variables that resulted in the best-fit models. After the variable selection, multiple linear regression (MLR) was utilized to construct linear QSPR models. The resulting QSPR equations indicated that the orbital energies, quantum chemical indices (i.e. electronegativity and softness) and localization of charge in molecules are important factors in the first oxidation and reduction potentials of PhQE and PhIE. The quantum-chemical calculations show that the HOMO and LUMO of both PhQE and PhIE derivatives are localized on the donor-substituted phenyl moiety, and the quinolinyl and isoquinolinyl acceptor moiety respectively. Thus, it was proposed that the first reduction and oxidation potentials can be ascribed to reduction at the quinolinyl acceptor moiety, and oxidation at the donor-substituted phenyl moiety.

  4. Drug structure–transport relationships

    OpenAIRE

    Roberts, Michael S.

    2010-01-01

    Malcolm Rowland has greatly facilitated an understanding of drug structure–pharmacokinetic relationships using a physiological perspective. His view points, covering a wide range of activities, have impacted on my own work and on my appreciation and understanding of our science. This overview summarises some of our parallel activities, beginning with Malcolm’s work on the pH control of amphetamine excretion, his work on the disposition of aspirin and on the application of clearance concepts i...

  5. Relationship between oxide-ion conduction and dielectric properties of Gd2Zr2O7 having a fluorite-type structure

    International Nuclear Information System (INIS)

    The relationship between electrical conduction and dielectric properties was investigated for the oxide-ion conductor Gd2Zr2O7 having a fluorite-type structure. Computer simulation clarified that the anomalously large dielectric constant (?r') was successfully explained by the superposition of the Debye-type polarization and the electrolyte-electrode interfacial polarization. Two Debye-type relaxations were observed at 673 K and above. The lower-frequency relaxation was ascribed to the dopant-vacancy associate, (GdCe' - Vo··-GdCe'), and the higher one to the long range migration of oxide ions on the basis of the discussions of both the activation energies and the relaxation frequencies. The frequency dependences of both the ac conductivity (?ac) and the loss tangent (tan?) were also successfully explained using the dielectric parameters of the Debye-type dopant-vacancy associates. (author)

  6. Relationship Between Attitude Properties and Psychological Commitment

    Directory of Open Access Journals (Sweden)

    JAEHYUN HA

    2011-01-01

    Full Text Available The purpose of the study was to examine the relationship between attitude properties and psychological commitment to a sports team. In addition, this study attempted to examine whether there were gender differences in the relationship between attitude properties and psychological commitment to the team. A total of 453 questionnaires were distributed and returned from students at a large public university. Out of 453, twenty-nine were excluded because they were not applicable. 424 questionnaires were utilized for the data analysis. Data were analyzed with correlation analysis, Cron-bach’s ? coefficient, confirmatory factor analysis, and three structural models (total data, male data, and female data. Based on the results of the total data, direct experience, importance, certainty, and extremity directly contributed to psychological commitment to the team. The results also indicated that direct experience, importance, and extremity were significantly related to psychological commitment to the team for males, while for females, only importance was a significant predictor of psychological commitment to the team.

  7. QUANTITATIVE STRUCTURE–PROPERTY RELATIONSHIP (QSPR STUDY OF KOVATS RETENTION INDICES OF SOME OF ADAMANTANE DERIVATIVES BYTHE GENETIC ALGORITHM AND MULTIPLE LINEAR REGRESSION (GA-MLR METHOD

    Directory of Open Access Journals (Sweden)

    Z. Bayat

    2011-05-01

    Full Text Available A quantitative structure–property relationship (QSPR study was performed to develop models those relate the structures of 65 Kovats retention index (RI of adamantane derivatives. Molecular descriptors derived solely from 3D structures of the molecular compounds. A genetic algorithm was also applied as a variable selection tool in QSPR analysis. The models were constructed using 52 molecules as training set, and predictive ability tested using 13 compounds. Modeling of RI of Adamantane derivatives as a function of the theoretically derived descriptors was established by multiple linear regression (MLR. The usefulness of the quantum chemical descriptors, calculated at the level of the DFT theories using 6-311+G** basis set for QSAR study of adamantane derivatives was examined. The use of descriptors calculated only from molecular structure eliminates the need to experimental determination of properties for use in the correlation and allows for the estimation of RI for molecules not yet synthesized. Application of the developed model to testing set of 13 drug organic compounds demonstrates that the model is reliable with goo predictive accuracy and simple formulation. The prediction results are in good agreement with the experimental value. A multi-parametric equation containing maximum Four descriptors at B3LYP/6-31+G** method with good statistical qualities (R2train=0.913, Ftrain=97.67, R2test=0.770, Ftest=3.21, Q2LOO=0.895, R2adj=0.904, Q2LGO=0.844 was obtained by Multiple Linear Regression using stepwise method.

  8. 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.)

  9. 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.

  10. 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.

  11. 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.

  12. 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 (<3) act as efficient gelators in a variety of solvents. However, the cholesteryl derivatives with longer alkyl chains (11 spacer) and adamantyl derivatives did not possess this ability. Self-assembled fibrous structures were constructed by gelators with short alkyl chains (<3), while flower-like structures were constructed by gelators with moderately longer alkyl chains (3-6) at their respective critical gelation concentrations (CGCs) according to SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) analyses. In some cases, a partial/weak gel was observed in different solvents, which exhibited uniform spherical 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

  13. Design and prediction of new anticoagulants as a selective Factor IXa inhibitor via three-dimensional quantitative structure-property relationships of amidinobenzothiophene derivatives

    Directory of Open Access Journals (Sweden)

    Gao JS

    2015-03-01

    Full Text Available Jia-Suo Gao,1* Xu-Peng Tong,2* Yi-Qun Chang,1 Yu-Xuan He,1 Yu-Dan Mei,1 Pei-Hong Tan,1 Jia-Liang Guo,1 Guo-Chao Liao,3 Gao-Keng Xiao,1 Wei-Min Chen,1 Shu-Feng Zhou,4 Ping-Hua Sun1 1Guangdong Province Key Laboratory of Pharmacodynamic Constituents of Traditional Chinese Medicine and New Drugs Research, College of Pharmacy, Jinan University, Guangzhou, People’s Republic of China; 2College of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of China; 3Department of Chemistry, Wayne State University, Detroit, Michigan, USA; 4College of Pharmacy, University of South Florida, Tampa, FL, USA *These authors contributed equally to this work Abstract: Factor IXa (FIXa, a blood coagulation factor, is specifically inhibited at the initiation stage of the coagulation cascade, promising an excellent approach for developing selective and safe anticoagulants. Eighty-four amidinobenzothiophene antithrombotic derivatives targeting FIXa were selected to establish three-dimensional quantitative structure–activity relationship (3D-QSAR and three-dimensional quantitative structure–selectivity relationship (3D-QSSR models using comparative molecular field analysis and comparative similarity indices analysis methods. Internal and external cross-validation techniques were investigated as well as region focusing and bootstrapping. The satisfactory q2 values of 0.753 and 0.770, and r2 values of 0.940 and 0.965 for 3D-QSAR and 3D-QSSR, respectively, indicated that the models are available to predict both the inhibitory activity and selectivity on FIXa against Factor Xa, the activated status of Factor X. This work revealed that the steric, hydrophobic, and H-bond factors should appropriately be taken into account in future rational design, especially the modifications at the 2'-position of the benzene and the 6-position of the benzothiophene in the R group, providing helpful clues to design more active and selective FIXa inhibitors for the treatment of thrombosis. On the basis of the three-dimensional quantitative structure–property relationships, 16 new potent molecules have been designed and are predicted to be more active and selective than Compound 33, which has the best activity as reported in the literature. Keywords: CoMFA, CoMSIA, 3D-QSAR, 3D-QSSR, benzothiophene antithrombosis

  14. 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

  15. 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

    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...

  16. The relationship of physico-chemical properties and structure to the differential antiplasmodial activity of the cinchona alkaloids

    OpenAIRE

    Meyer David J; Adagu Ipemida S; Craig John C; Warhurst David C; Lee Sylvia Y

    2003-01-01

    Abstract Background The 8-amino and 9-hydroxy substituents of antimalarial cinchona alkaloids have the erythro orientation while their inactive 9-epimers are threo. From the X-ray structures a 90° difference in torsion angle between the N1-H1 and C9-O12 bonds in the two series is believed to be important. In order to kill the malaria parasite, alkaloids must cross the erythrocyte and parasite membranes to accumulate in the acid digestive vacuole where they prevent detoxication of haematin pro...

  17. Structural properties and evolutionary relationships of PspA, a surface protein of Streptococcus pneumoniae, as revealed by sequence analysis.

    OpenAIRE

    Yother, J; Briles, D E

    1992-01-01

    Analysis of the sequence for the gene encoding PspA (pneumococcal surface protein A) of Streptococcus pneumoniae revealed the presence of four distinct domains in the mature protein. The structure of the N-terminal half of PspA was highly consistent with that of an alpha-helical coiled-coil protein. The alpha-helical domain was followed by a proline-rich domain (with two regions in which 18 of 43 and 5 of 11 of the residues are prolines) and a repeat domain consisting of 10 highly conserved 2...

  18. Epicardial Fat in Nonalcoholic Fatty Liver Disease: Properties and Relationships With Metabolic Factors, Cardiac Structure, and Cardiac Function.

    Science.gov (United States)

    Psychari, Stavroula N; Rekleiti, Nectaria; Papaioannou, Nikolaos; Varhalama, Evangelia; Drakoulis, Christos; Apostolou, Thomas S; Iliodromitis, Efstathios K

    2016-01-01

    Nonalcoholic fatty liver disease (NAFLD) is closely related to insulin resistance and the metabolic syndrome and might be an important cardiovascular (CV) risk factor. Epicardial adipose tissue (EAT) has been implicated in the pathogenesis of obesity-related CV disease. In an NAFLD population, we investigated EAT thickness and its possible relations to NAFLD and cardiac structure and function. This was an observational study of 57 patients with NAFLD and 48 age-matched controls. Patients with NAFLD had significantly higher body mass index (P fat was not significantly related to NAFLD per se, but diabetes, glucose metabolism, and inflammation were closely related to its thickness. PMID:25818101

  19. 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.

  20. The relationship of physico-chemical properties and structure to the differential antiplasmodial activity of the cinchona alkaloids

    Directory of Open Access Journals (Sweden)

    Meyer David J

    2003-09-01

    Full Text Available Abstract Background The 8-amino and 9-hydroxy substituents of antimalarial cinchona alkaloids have the erythro orientation while their inactive 9-epimers are threo. From the X-ray structures a 90° difference in torsion angle between the N1-H1 and C9-O12 bonds in the two series is believed to be important. In order to kill the malaria parasite, alkaloids must cross the erythrocyte and parasite membranes to accumulate in the acid digestive vacuole where they prevent detoxication of haematin produced during haemoglobin breakdown. Methods Ionization constants, octanol/water distribution and haematin interaction are examined for eight alkaloids to explain the influence of small structural differences on activity. Results Erythro isomers have a high distribution ratio of 55:1 from plasma to the erythrocyte membrane, while for the more basic threo epimers this is only 4.5:1. This gives an increased transfer rate of the erythro drugs into the erythrocyte and thence into the parasite vacuole where their favourable conformation allows interaction with haematin, inhibiting its dimerization strongly (90 ± 7% and thereby killing the parasite. The threo compounds not only enter more slowly but are then severely restricted from binding to haematin by the gauche alignment of their N1-H1 and C9-O12 bonds. Confirmatory molecular models allowed measurement of angles and bond lengths and computation of the electronic spectrum of a quinine-haematin complex. Conclusion Differences in the antiplasmodial activity of the erythro and threo cinchona alkaloids may therefore be attributed to the cumulative effects of lipid/aqueous distribution ratio and drug-haematin interaction. Possible insights into the mechanism of chloroquine-resistance are discussed.

  1. SnO2 nanocrystals synthesized by microwave-assisted hydrothermal method: towards a relationship between structural and optical properties

    International Nuclear Information System (INIS)

    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 SnO2 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?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 SnO2 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.

  2. Phase transition induced by pressure in TbCrO{sub 4} oxide: Relationship structure-properties

    Energy Technology Data Exchange (ETDEWEB)

    Climent, E.; Gallardo, J.M. [Dpto. Quimica Inorganica, Facultad Ciencias Quimicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid (Spain); Romero de Paz, J. [CAI Tecnicas Fisicas, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Taira, N. [Dpto. Quimica Inorganica, Facultad Ciencias Quimicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid (Spain); Saez Puche, R., E-mail: rsp92@quim.ucm.e [Dpto. Quimica Inorganica, Facultad Ciencias Quimicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid (Spain)

    2009-12-04

    Terbium chromate TbCrO{sub 4}, which has been described as belonging to the zircon-type structure showing tetragonal symmetry, space group I4{sub 1}/amd, has been prepared as a dimorphic compound. When the zircon-type TbCrO{sub 4} polymorph is treated at 40 kbar and 833 K takes place a phase transition to the tetragonal scheelite-type TbCrO{sub 4} polymorph, space group I4{sub 1}/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 TbCrO{sub 4} polymorph behaves as ferromagnetic with a Curie temperature of 22 K, while the scheelite-type TbCrO{sub 4} polymorph is antiferromagnetic with T{sub N} = 29 K. M vs. H plots at different temperatures show the presence of a metamagnetic transition for the scheelite-type TbCrO{sub 4} 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.

  3. 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

  4. Relationship between structural characteristics and photoluminescent properties of (La1-xEux)2M2O7 (M=Zr, Hf, Sn) pyrochlores

    International Nuclear Information System (INIS)

    Eu-doped pyrochlores, La2M2O7 (M=Zr, Hf, Sn), were synthesized by solid-state reaction at a temperature range of 1473 and 1673 K, and their structures and optical properties were characterized by X-ray Rietveld analysis, field emission scanning electron microscope (FE-SEM), and photoluminescent spectroscopy. The Rietveld analysis indicated that the distortion of the (EuO8)n- scalenohedra increased with decreasing ionic radii of the M4+ ion, and the crystallinity increased with the sintering temperature. The splitting width of 5D0-7F1 transition of Eu3+ ions increased with the distortion of the (EuO8)n- scalenohedra. The luminescent intensity ratio of magnetic dipole transitions to electronic dipole transitions decreased with the crystallinity, and the chromaticity changed from deep-red to orange-red. The relationship between the chromaticity of phosphors and the crystallinity was clarified, and the control of crystallinity is an important factor that provides phosphors with required chromaticity

  5. A new quantitative structure-property relationship model to predict bioconcentration factors of polychlorinated biphenyls (PCBs) in fishes using E-state index and topological descriptors.

    Science.gov (United States)

    de Melo, Eduardo Borges

    2012-01-01

    A quantitative structure-property relationship (QSPR) study for predicting the logarithm of bioconcentration factors (LogBCF) of polychlorinated biphenyls (PCBs) is presented in this work. For this, the descriptors were obtained using only the Simplified Molecular Input Line Entry System (SMILES) strings in the free web server Parameter Client. The model was built using the Partial Least Squares (PLS) regression method. The best model presented five descriptors (one E-state index and four topological descriptors) and a high quality for fit, internal, and external predictions. The leave-N-out (LNO) cross validation and the y-randomization test showed the model is robust and has no shown chance correlation. With a second test set, the model was compared to other models and presented a root mean square error (RMSE) very close to the best model. The mechanistic interpretation was corroborated by other works in the literature and by the descriptors' theory. Thus, the results meet the five Organization for Economic Co-operation and Development (OECD) principles for validation of QSA(P)R models, and it is expected the model can effectively predict the BCF values in fishes of the PCB congeners without highly reliable experimental BCF. PMID:21959189

  6. Non-covalent interaction of dietary polyphenols with total plasma proteins of type II diabetes: molecular structure/property-affinity relationships.

    Science.gov (United States)

    Xiao, Jianbo; Zhao, Yaru; Wang, Hui; Yuan, Yongming; Yang, Fan; Zhang, Chao; Kai, Guoyin

    2011-11-01

    The molecular structure/property-affinity relationships of dietary polyphenols non-covalently binding to total plasma proteins of type II diabetes (IIDTPP) were investigated by comparing the binding constants obtained from the fluorescence titration method. An additional methoxy group in flavonoids increased their binding affinities for IIDTPP by 1.38 to 15.85 times. The hydroxylation at the 4' position (Ring B) of flavonols and the 5 position (Ring A) of isoflavones weakened the binding affinities; however, hydroxylation at other positions on flavonoids slightly enhanced or little affected the binding affinities for IIDTPP. The glycosylation of flavonoids slightly decreased or little affected the affinities for IIDTPP by less than 1 order of magnitude. The hydrogenation of the C2[double bond, length as m-dash]C3 double bond of flavone, 6-hydroxyflavone, 6-methoxyflavone and myricetin decreased the binding affinities. The galloylation of catechins significantly improved the binding affinities with IIDTPP approximately 10 to 1000 times. The esterification of gallic acid increased its binding affinity. The hydrophobic force played an important role in the binding interaction between polyphenols and IIDTPP. PMID:21947088

  7. Quantitative Structure-Property Relationship (QSPR) Models for a Local Quantum Descriptor: Investigation of the 4- and 3-Substituted-Cinnamic Acid Esterification.

    Science.gov (United States)

    Rodrigues-Santos, Cláudio E; Echevarria, Aurea; Sant'Anna, Carlos M R; Bitencourt, Thiago B; Nascimento, Maria G; Bauerfeldt, Glauco F

    2015-01-01

    In this work, the theoretical description of the 4- and 3-substituted-cinnamic acid esterification with different electron donating and electron withdrawing groups was performed at the B3LYP and M06-2X levels, as a two-step process: the O-protonation and the nucleophile attack by ethanol. In parallel, an experimental work devoted to the synthesis and characterization of the substituted-cinnamate esters has also been performed. In order to quantify the substituents effects, quantitative structure-property relationship (QSPR) models based on the atomic charges, Fukui functions and the Frontier Effective-for-Reaction Molecular Orbitals (FERMO) energies were investigated. In fact, the Fukui functions, ƒ?C and ƒ(-)O, indicated poor correlations for each individual step, and in contrast with the general literature, the O-protonation step is affected both by the FERMO energies and the O-charges of the carbonyl group. Since the process was shown to not be totally described by either charge- or frontier-orbitals, it is proposed to be frontier-charge-miscere controlled. Moreover, the observed trend for the experimental reaction yields suggests that the electron withdrawing groups favor the reaction and the same was observed for Step 2, which can thus be pointed out as the determining step. PMID:26402661

  8. Quantitative Structure–Property Relationship (QSPR Models for a Local Quantum Descriptor: Investigation of the 4- and 3-Substituted-Cinnamic Acid Esterification

    Directory of Open Access Journals (Sweden)

    Cláudio E. Rodrigues-Santos

    2015-09-01

    Full Text Available In this work, the theoretical description of the 4- and 3-substituted-cinnamic acid esterification with different electron donating and electron withdrawing groups was performed at the B3LYP and M06-2X levels, as a two-step process: the O-protonation and the nucleophile attack by ethanol. In parallel, an experimental work devoted to the synthesis and characterization of the substituted-cinnamate esters has also been performed. In order to quantify the substituents effects, quantitative structure–property relationship (QSPR models based on the atomic charges, Fukui functions and the Frontier Effective-for-Reaction Molecular Orbitals (FERMO energies were investigated. In fact, the Fukui functions, ƒ+C and ƒ?O, indicated poor correlations for each individual step, and in contrast with the general literature, the O-protonation step is affected both by the FERMO energies and the O-charges of the carbonyl group. Since the process was shown to not be totally described by either charge- or frontier-orbitals, it is proposed to be frontier-charge-miscere controlled. Moreover, the observed trend for the experimental reaction yields suggests that the electron withdrawing groups favor the reaction and the same was observed for Step 2, which can thus be pointed out as the determining step.

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

    Science.gov (United States)

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

    2009-05-20

    A series of highly soluble and fluorescent, at core tetraaryloxy-substituted and in imide positions hydrogen atom containing perylene bisimide (PBI) dyes 1a-e with varying peripheral side chains have been synthesized and thoroughly characterized. The self-assembly of these PBIs has been studied in detail by UV/vis, linear dichroism (LD) and circular dichroism (CD) spectroscopy, and scanning probe microscopy (AFM, STM). These studies revealed that the present PBIs self-assemble into extended double string cables, which consist of two hydrogen-bonded supramolecular polymeric chains of densely packed and strongly excitonically coupled PBI chromophores, providing highly fluorescent J-aggregates. The aggregation strength ("melting" temperature) and the fluorescence properties of these J-aggregates are dependent on the number and chain length of the peripheral alkoxy substituents, thus revealing a structure-property relationship. In contrast to previously reported assemblies of PBIs, for which the aggregation process is described by the isodesmic (or equal K) model, a cooperative nucleation-elongation mechanism applies for the aggregation of the present assemblies as revealed by concentration-dependent UV/vis absorption studies with the chiral PBI 1e, providing equilibrium constants for dimerization (= nucleation) of K(2) = 13 +/- 11 L mol(-1) and for elongation of K = 2.3 +/- 0.1 x 10(6) L mol(-1) in methylcyclohexane (MCH). LD spectroscopic measurements have been performed to analyze the orientation of the monomers within the aggregates. The nonlinearity of chiral amplification in PBI aggregates directed by sergeants-and-soldiers principle has been elucidated by coaggregation experiments of different PBI dyes using CD spectroscopy. The dimensions as well as the molecular arrangement of the monomeric units in assemblies have been explored by atomic force microscopy (AFM) and scanning tunneling microscopy (STM). PMID:19388696

  10. Investigation into the structure–property relationship and technical properties of TPEs and TPVs derived from ethylene octene copolymer (EOC) and polydimethyl siloxane (PDMS) rubber blends

    Science.gov (United States)

    Padmanabhan, R.; Naskar, Kinsuk; Nando, Golok B.

    2015-10-01

    This work focuses on the study of thermoplastic vulcanizates based on ethylene octene copolymer (EOC) and poly dimethyl siloxane (PDMS) rubber prepared by melt mixing technique using dicumyl peroxide (DCP). It is found that the addition of peroxide causes crosslinking in both the phases. However, crosslinking without affecting the crystallinity of the EOC polymer leads to tremendous improvement in the mechanical properties, including the tensile strength which has improved by nearly 60%. For better understanding about the crosslinking characteristics of thermoplastic vulcanizates (TPVs), significant correlation has been made between the vulcanized network and the physico-mechanical properties. Further, the dynamic mechanical properties and creep behavior of these thermoplastic elastomers (TPEs) and TPVs have also been studied. It is inferred that the TPVs show a 19% decrease in the creep compliance, i.e. higher creep resistance compared to uncrosslinked blends. Subsequently, the morphology of the blends before and after vulcanization shows a decrease in the spherical PDMS domains from 0.8 ?m to > 0.4 ?m. Ageing and reprocessing studies of the prepared TPVs also show better physico-mechanical properties even after reprocessing twice. Thus, the prepared TPVs may have tremendous applications in automobile sectors.

  11. 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.; Burgert, I.

    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 ...

  12. Structure–property relationships along the Fe-substituted CuInS{sub 2} series: Tuning of thermoelectric and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, Johanna D. [Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States); Gourdon, Olivier [Chemical and Engineering Materials Division, Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); International Centre for Diffraction Data, 12 Campus Boulevard, Newtown Square, PA 19073-3273 (United States); Ranmohotti, Kulugammana G.S.; Takas, Nathan J.; Djieutedjeu, Honore; Poudeu, Pierre F.P. [University of Michigan, Department of Materials Science and Engineering, Laboratory of Emerging Energy and Electronic Materials LE3M, Ann Arbor, MI 48109 (United States); Aitken, Jennifer A., E-mail: aitkenj@duq.edu [Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15282 (United States)

    2014-09-15

    CuIn{sub 1?x}Fe{sub x}S{sub 2} (x = 0–0.15) was synthesized via high-temperature, solid-state synthesis. Rietveld refinements using the neutron and synchrotron powder diffraction data indicate that all Fe-substituted materials are phase pure with the exception of the CuIn{sub 0.85}Fe{sub 0.15}S{sub 2} sample, which contains a minute secondary phase. These refinements also verify that iron resides on the indium site in the CuIn{sub 1?x}Fe{sub x}S{sub 2} materials. CuIn{sub 0.875}Fe{sub 0.125}S{sub 2} displayed the lowest total thermal conductivity of the series, 1.37 W m{sup ?1} K{sup ?1} at 570 K, as well as the highest thermopower, ?172 ?V K{sup ?1} at 560 K. The electrical conductivity increases over six times upon going from CuInS{sub 2} to CuIn{sub 0.875}Fe{sub 0.125}S{sub 2}. These improved properties result in an increase in the thermoelectric figure of merit (ZT) of CuInS{sub 2} by over an order of magnitude for the x = 0.125 sample. Magnetic measurements reveal the x = 0–0.10 samples to be paramagnetic, while the sample in which x = 0.125 displays ferromagnetic ordering below 95 K. - Highlights: • Up to 12.5% of the In{sup 3+} is replaced with Fe{sup 3+} in CuInS{sub 2}. • Rietveld refinements using powder diffraction data show iron on the indium site. • CuIn{sub 0.875}Fe{sub 0.125}S{sub 2} is ferromagnetic below 95 K. • The thermal conductivity of CuIn{sub 0.875}Fe{sub 0.125}S{sub 2} is 1.37 W m{sup ?1} K{sup ?1} at 570 K. • The ZT of CuInS{sub 2} increased by over an order of magnitude with iron substitution.

  13. The structural properties of sustainable, continuous change

    DEFF Research Database (Denmark)

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

    2013-01-01

    Recent studies show that the relationship between structure and inertia in changing environments may be more complex than previously held and that the theoretical logics tying inertia with flexibility and efficiency remain incomplete. Using a computational model, this article aims to clarify this relationship by exploring what structural properties enable continuous change in inertia-generating organizations and what their performance consequences are in dynamic environments. The article has thr...

  14. Structural Antitumoral Activity Relationships of Synthetic Chalcones

    OpenAIRE

    Cesar Echeverria; Juan Francisco Santibañez; Oscar Donoso-Tauda; Escobar, Carlos A.; Rodrigo Ramirez-Tagle

    2009-01-01

    Relationships between the structural characteristic of synthetic chalcones and their antitumoral activity were studied. Treatment of HepG2 cells for 24 h with synthetic 2’-hydroxychalcones resulted in apoptosis induction and dose-dependent inhibition of cell proliferation. The calculated reactivity indexes and the adiabatic electron affinities using the DFT method including solvent effects, suggest a structure-activity relationship between the Chalcones structure and the apoptosis in Hep...

  15. Microstructure-property relationships in discontinuous fiber reinforced thermoplastic composites

    Energy Technology Data Exchange (ETDEWEB)

    Vyakarnam, M.N.; Drzal, L.T. [Michigan State Univ., East Lansing, MI (United States)

    1996-12-31

    A novel Aligned Discontinuous Fiber (ADF) composite process has been developed to optimize performance and processability of discontinuous fiber thermoplastic composites. The principle feature of this process is the alignment of the fibers using electric fields in air. The successful control of the orientation state of the fibers using the ADF process led to the fabrication of micro-structure controlled discontinuous fiber composites and the subsequent investigation into the microstructure-property relationships of these materials.

  16. 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.

  17. 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.

  18. 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.

  19. Structure-property relationships for N-phosphoryl substituted E,E-3,5-bis(arylidene)piperid-4-ones

    Science.gov (United States)

    Khrustalev, Victor N.; Nayani, Shravana L.; Leonova, Evgeniya S.; Puntus, Lada N.; Summeth, David M.; Makarov, Michael V.; Odinets, Irina L.; Timofeeva, Tatiana V.

    2013-07-01

    The structures and one- and two-photon absorption properties of a series of phosphoryl substituted 3,5-bis(arylidene)piperid-4-ones bearing amino groups, nitro groups or fluorine atoms in the para-positions of the arene rings have been investigated. The measurable two-photon absorption cross sections and low fluorescence quantum yields have been observed for piperidone compounds with the general D-?-A-?-D structure. However, no fluorescence and, consequently, two-photon absorption cross sections (in the frame of the experimental method used) have been observed for the compounds containing the electron withdrawing substituents, such as nitro groups or fluorine atoms in the side aryl ligands. The X-ray diffraction analysis revealed the tendency of increasing of cytotoxic activity with the increase of planarity of the main backbone of phosphoryl substituted piperidone molecules. The results obtained furnish a link between structural features of these molecules and their photo- and cytotoxic activities to allow a design of new compounds of this class with the tuning of biological properties.

  20. Structure–Property Relationship Study of Substitution Effects on Isoindigo-Based Model Compounds as Electron Donors in Organic Solar Cells

    Science.gov (United States)

    2015-01-01

    We designed and synthesized a series of isoindigo-based derivatives to investigate how chemical structure modification at both the 6,6?- and 5,5?-positions of the core with electron-rich and electron-poor moieties affect photophysical and redox properties as well as their solid-state organization. Our studies reveal that 6,6?-substitution on the isoindigo core results in a stronger intramolecular charge transfer band due to strong electronic coupling between the 6,6?-substituent and the core, whereas 5,5?-substitution induces a weaker CT band that is more sensitive to the electronic nature of the substituents. In the solid state, 6,6?-derivatives generally form J-aggregates, whereas 5,5?-derivatives form H-aggregates. With only two branched ethylhexyl side chains, the 6,6?-derivatives form organized lamellar structures in the solid state. The incorporation of electron-rich benzothiophene, BT, substituents further enhances ordering, likely because of strong intermolecular donor–acceptor interactions between the BT substituent and the electron-poor isoindigo core on neighboring compounds. Collectively, the enhanced photophysical properties and solid-state organization of the 6,6?-benzothiophene substituted isoindigo derivative compared to the other isoindigo derivatives examined in this study resulted in solar cells with higher power conversion efficiencies when blended with a fullerene derivative. PMID:25089728

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

    OpenAIRE

    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 ...

  3. Structure-Function-Property-Design Interplay in Biopolymers: Spider Silk

    OpenAIRE

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L.

    2013-01-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures, and mechanical properties found in different types of spider silks are described, along with a discussio...

  4. Novel Self-Dyed Wholly Aromatic Polyamide-Hydrazides Covalently Bonded with Azo Groups in Their Main Chains: 1. Structure-Property Relationships

    Directory of Open Access Journals (Sweden)

    Nadia A. Mohamed

    2012-11-01

    Full Text Available Twelve novel intrinsically colored wholly aromatic azopolyamide-hydrazides containing various proportions of para- and meta-phenylene units were successfully synthesized by a low temperature (?10 °C solution polycondensation reaction of either 4-amino-3-hydroxybenzhydrazide (4A3HBH or 3-amino-4-hydroxybenzhydrazide (3A4HBH with an equimolar amount of either 4,4'-azodibenzoyl chloride (4,4'ADBC, 3,3'-azodibenzoyl chloride (3,3'ADBC, or mixtures of various molar ratios of 4,4'ADBC and 3,3'ADBC in anhydrous N,N-dimethyl acetamide (DMAc containing 3% (wt/v LiCl as a solvent. The structures of the polymers were proven by elemental analysis, FTIR, 1H- and 13C-NMR spectroscopy. The polymers’ properties were strongly affected by their various structures. The intrinsic viscosities of the polymers were ranged from 0.7 to 4.75 dL g?1 and increased with the para-phenylene units content. The polymers are partially soluble in DMAc, dimethyl formamide (DMF and N-methyl-2-pyrrolidone (NMP. Their solubility increases with the introduction of meta-phenylene moieties into the polymer chains. The polymers exhibit a great affinity for water sorption. Their hydrophilicity increases as a function of the content of meta-phenylene rings incorporated into the polymer. Mechanical properties of the polymer films are improved markedly by substitution of para-phenylene units for meta-phenylene units. The completely para-oriented type polymer has the best thermal and thermo-oxidative stability relative to those of the other polymers.

  5. Quantitative structure-property relationships of electroluminescent materials: Artificial neural networks and support vector machines to predict electroluminescence of organic molecules

    Indian Academy of Sciences (India)

    Alana Fernandes Golin; Ricardo Stefani

    2013-12-01

    Electroluminescent compounds are extensively used as materials for application in OLED. In order to understand the chemical features related to electroluminescence of such compounds, QSPR study based on neural network model and support vector machine was developed on a series of organic compounds commonly used in OLED development. Radial-basis function-SVM model was able to predict the electroluminescence with good accuracy ( = 0.90). Moreover, RMSE of support vector machine model is approximately half of RMSE observed for artificial neural networks model, which is significant from the point of view of model precision, as the dataset is very small. Thus, support vector machine is a good method to build QSPR models to predict the electroluminescence of materials when applied to small datasets. It was observed that descriptors related to chemical bonding and electronic structure are highly correlated with electroluminescence properties. The obtained results can help in understating the structural features related to the electroluminescence, and supporting the development of new electroluminescent materials.

  6. 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.

  7. Toward a “structural BLAST”: Using structural relationships to infer function

    OpenAIRE

    Dey, Fabian; Cliff Zhang, Qiangfeng; Petrey, Donald; Honig, Barry

    2013-01-01

    We outline a set of strategies to infer protein function from structure. The overall approach depends on extensive use of homology modeling, the exploitation of a wide range of global and local geometric relationships between protein structures and the use of machine learning techniques. The combination of modeling with broad searches of protein structure space defines a “structural BLAST” approach to infer function with high genomic coverage. Applications are described to the prediction of p...

  8. Dissecting the relationship between protein structure and sequence variation

    Science.gov (United States)

    Shahmoradi, Amir; Wilke, Claus; Wilke Lab Team

    2015-03-01

    Over the past decade several independent works have shown that some structural properties of proteins are capable of predicting protein evolution. The strength and significance of these structure-sequence relations, however, appear to vary widely among different proteins, with absolute correlation strengths ranging from 0 . 1 to 0 . 8 . Here we present the results from a comprehensive search for the potential biophysical and structural determinants of protein evolution by studying more than 200 structural and evolutionary properties in a dataset of 209 monomeric enzymes. We discuss the main protein characteristics responsible for the general patterns of protein evolution, and identify sequence divergence as the main determinant of the strengths of virtually all structure-evolution relationships, explaining ~ 10 - 30 % of observed variation in sequence-structure relations. In addition to sequence divergence, we identify several protein structural properties that are moderately but significantly coupled with the strength of sequence-structure relations. In particular, proteins with more homogeneous back-bone hydrogen bond energies, large fractions of helical secondary structures and low fraction of beta sheets tend to have the strongest sequence-structure relation. BEACON-NSF center for the study of evolution in action.

  9. 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…

  10. 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

  11. 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.

  12. 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

  13. Combining Theoretical Perspectives on the Organizational Structure-Performance Relationship

    Directory of Open Access Journals (Sweden)

    Starling David Hunter

    2015-08-01

    Full Text Available Much of the literature linking organization structure to performance falls into two broad research streams. One stream concerns formal structure – the hierarchy of authority or reporting relationships as well as the degree of standardization, formalization, specialization, etc. The impact of formal structure and other elements of organization design on performance is typically contingent on factors such as strategic orientation, task characteristics, and environmental conditions. The other research stream focuses on informal structure – a network of interpersonal and intra-organizational relationships. Properties of informal structure are typically shown to have a more direct (less contingent impact on organizational performance. Despite these pronounced differences in the conceptualization of organization structure, considerable overlap and complementarity exist between the two research streams. In this article, I compare and contrast a pair of exemplars from each stream – the information processing perspective and the social network perspective – with respect to their conceptualizations of organization structure and its relationship to performance. Several recommendations for future research that combines the two approaches are offered.

  14. 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.

  15. Structural Properties of Ego Networks

    CERN Document Server

    Gupta, Sidharth; Lerman, Kristina

    2014-01-01

    The structure of real-world social networks in large part determines the evolution of social phenomena, including opinion formation, diffusion of information and influence, and the spread of disease. Globally, network structure is characterized by features such as degree distribution, degree assortativity, and clustering coefficient. However, information about global structure is usually not available to each vertex. Instead, each vertex's knowledge is generally limited to the locally observable portion of the network consisting of the subgraph over its immediate neighbors. Such subgraphs, known as ego networks, have properties that can differ substantially from those of the global network. In this paper, we study the structural properties of ego networks and show how they relate to the global properties of networks from which they are derived. Through empirical comparisons and mathematical derivations, we show that structural features, similar to static attributes, suffer from paradoxes. We quantify the diff...

  16. Structure-function-property-design interplay in biopolymers: spider silk.

    Science.gov (United States)

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L

    2014-04-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures and mechanical properties found in different types of spider silks are described, along with a discussion of artificial spinning of these proteins and their bioapplications, including the role of silks in biomineralization and fabrication of biomaterials with controlled properties. PMID:23962644

  17. Structure-mechanics relationships in mineralized tendons.

    Science.gov (United States)

    Spiesz, Ewa M; Zysset, Philippe K

    2015-12-01

    In this paper, we review the hierarchical structure and the resulting elastic properties of mineralized tendons as obtained by various multiscale experimental and computational methods spanning from nano- to macroscale. The mechanical properties of mineralized collagen fibres are important to understand the mechanics of hard tissues constituted by complex arrangements of these fibres, like in human lamellar bone. The uniaxial mineralized collagen fibre array naturally occurring in avian tendons is a well studied model tissue for investigating various stages of tissue mineralization and the corresponding elastic properties. Some avian tendons mineralize with maturation, which results in a graded structure containing two zones of distinct morphology, circumferential and interstitial. These zones exhibit different amounts of mineral, collagen, pores and a different mineral distribution between collagen fibrillar and extrafibrillar space that lead to distinct elastic properties. Mineralized tendon cells have two phenotypes: elongated tenocytes placed between fibres in the circumferential zone and cuboidal cells with lower aspect ratios in the interstitial zone. Interestingly some regions of avian tendons seem to be predestined to mineralization, which is exhibited as specific collagen cross-linking patterns as well as distribution of minor tendon constituents (like proteoglycans) and loss of collagen crimp. Results of investigations in naturally mineralizing avian tendons may be useful in understanding the pathological mineralization occurring in some human tendons. PMID:25922092

  18. Spanish Version of the Savings Inventory-Revised: Adaptation, Psychometric Properties, and Relationship to Personality Variables

    Science.gov (United States)

    Tortella-Feliu, Miquel; Fullana, Miquel A.; Caseras, Xavier; Andion, Oscar; Torrubia, Rafael; Mataix-Cols, David

    2006-01-01

    The factor structure, psychometric properties, and relationship with personality variables of a Spanish version of the Savings Inventory-Revised (SI-R) are investigated in a sample of 381 undergraduate students. A maximum likelihood factor analysis suggests a three-factor structure, which is similar but not identical to that of the original…

  19. 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%.

  20. Microstructure-Property Relationships in Cast Irons

    International Nuclear Information System (INIS)

    Several cast irons, prepared with different chemical compositions and microstructures have been examined by extensive mechanical testing and optical and scanning electron microscopy (SEM). Properties arising from various microstructures are tabulated. Mechanical properties are shown to be a function of both the matrix and graphite (or carbide) forms. Changing the matrix from ferritic-pearlitic to bainitic-martensitic type results in effects similar to those experienced in steels containing these phases respectively. The influence of graphite (or carbides) on the final properties, however, is dictate by the respective shapes and distributions of these microstructural constituents. The coupled zone-eutectic region in gray cast iron is asymmetrical and inclined to the right-hand side in Fe-C equilibrium phase diagram. Consequently, hypereutectic compositions reveal dendrites of primary austenite. In white cast iron, the coupled zone symmetry is thought to arise from the high volume fraction of cementite which compensates for its growth rate anisotropy. (author)

  1. Structural and functional properties of designed globins

    Indian Academy of Sciences (India)

    Yasuhiro Isogai; Anna Ishii; Manabu Ishida; Masahiro Mukai; Motonori Ota; Ken Nishikawa; Tetsutaro Iizuka

    2000-06-01

    De novo design of artificial proteins is an essential approach to elucidate the principles of protein architecture and to understand specific functions of natural proteins and also to yield novel molecules for medical and industrial aims. We have designed artificial sequences of 153 amino acids to fit the main-chain framework of the sperm whale myoglobin structure based on the knowledge-based energy functions to evaluate the compatibility between protein tertiary structures and amino acid sequences. The synthesized artificial globins bind a single heme per protein molecule as designed, which show well-defined electrochemical and spectroscopic features characteristic of proteins with a low-spin heme. Redox and ligand binding reactions of the artificial heme proteins were investigated and these heme-related functions were found to vary with their structural uniqueness. Relationships between the structural and functional properties are discussed.

  2. 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.

  3. Antibacterial Barbituric Acid Analogues Inspired from Natural 3-Acyltetramic Acids; Synthesis, Tautomerism and Structure and Physicochemical Property-Antibacterial Activity Relationships

    Directory of Open Access Journals (Sweden)

    Yong-Chul Jeong

    2015-02-01

    Full Text Available The synthesis, tautomerism and antibacterial activity of novel barbiturates is reported. In particular, 3-acyl and 3-carboxamidobarbiturates exhibited antibacterial activity, against susceptible and some resistant Gram-positive strains of particular interest is that these systems possess amenable molecular weight, rotatable bonds and number of proton-donors/acceptors for drug design as well as less lipophilic character, with physicochemical properties and ionic states that are similar to current antibiotic agents for oral and injectable use. Unfortunately, the reduction of plasma protein affinity by the barbituric core is not sufficient to achieve activity in vivo. Further optimization to reduce plasma protein affinity and/or elevate antibiotic potency is therefore required, but we believe that these systems offer unusual opportunities for antibiotic drug discovery.

  4. Relationships between structure and superconducting properties in new ternary silicides of the systems: rare earths or thorium - transition metal (Rh or Ir) - silicon

    International Nuclear Information System (INIS)

    Nine families of ternary silices Msub(x)Tsub(y)Sisub(z) have been prepared in the rare earths of thorium (M) - transition metals (T = Th or Ir) - silicon systems: MT3Si2, MT2Si2 (two polymorphic forms), MTSi (TiNiSi and SrSi2-type), M2T3Si5, MTSi2, MTSi3 and M2TSi3. The occurence of superconductivity in these compounds has been related both to their crystal structure and composition

  5. Piperine and Derivatives: Trends in Structure-Activity Relationships.

    Science.gov (United States)

    Singh, Inder Pal; Choudhary, Alka

    2015-01-01

    Piperine is the main constituent of pepper, a commonly used kitchen spice and has been reported to possess various pharmacological activities. The structural features, an aromatic ring with a methylenedioxy bridge, a conjugated dienone system and a piperidine ring constituting an amide bond, possessed by the molecule have been considered important for the molecule to exhibit an array of bioactivities. Several modifications of above structural units have affected the biological properties of piperine, either enhancing or in some cases completely abolishing the activity. The present review emphasizes on the synthetic aspects of piperine along with the structure-activity relationships of its derivatives so as to rationalize the discovery of newer piperine based molecules. PMID:25915609

  6. Structure-barrier property relationship of biodegradable poly(butylene succinate) and poly[(butylene succinate)-co-(butylene adipate)] nanocomposites: influence of the rigid amorphous fraction.

    Science.gov (United States)

    Charlon, S; Marais, S; Dargent, E; Soulestin, J; Sclavons, M; Follain, N

    2015-11-28

    Composites composed of polyesters, poly(butylene succinate) (PBS) or poly[(butylene succinate)-co-(butylene adipate)] (PBSA), and 5 wt% of montmorillonite (CNa) or organo-modified montmorillonite (C30B) were melt-processed and transformed into films by either compression-molding or extrusion-calendering. XRD, rheological measurements and TEM images clearly indicated that films containing CNa are microcomposites, while nanocomposites were observed for those containing C30B. Using Flash DSC, it was possible, for the first time, not only to measure the heat capacity step at the glass transition of these two materials in their amorphous state, but also to investigate whether the preparation technique influenced the Rigid Amorphous Fraction (RAF) in our PBS- and PBSA-based nanocomposites. In this work, we have successfully shown the correlation between the microstructure of the films and their barrier properties, and especially the role played by the RAF. Indeed, the lowest permeabilities to gases and to water were determined in the films containing the highest RAF in both PBS- and PBSA-based materials. PMID:26489904

  7. The relationship of the magnetic properties of M (M =  Mn, Fe, Co)-doped ZnO single crystals and their electronic structures.

    Science.gov (United States)

    Tamura, T; Ozaki, H

    2009-01-14

    The electronic density of states and magnetic properties were investigated by tunneling spectroscopy and SQUID, respectively, for a series of 3d transition-metal (Mn, Fe, Co)-doped ZnO. By tunneling spectroscopy an additional density of states was observed in Mn- and Co-doped ZnO adjacent to the top of the valence band of the host ZnO. Instead, in the Fe-doped sample, a band of density of states was observed across the Fermi level in the mid-gap. The magnetization curve (M versus H) obtained by SQUID showed a ferromagnetic hysteresis at room temperature for the Fe-doped sample, whereas for the Mn- and Co-doped samples, the M versus H curve showed only a linear characteristic without hysteresis. From the comparison of the density of states and the magnetization characteristics, it is strongly suggested that the ferromagnetism in Fe-doped ZnO at room temperature originates from the half-filled Fe 3d band in the mid-gap of the host ZnO. PMID:21814002

  8. The relationship of the magnetic properties of M (M = Mn, Fe, Co)-doped ZnO single crystals and their electronic structures

    International Nuclear Information System (INIS)

    The electronic density of states and magnetic properties were investigated by tunneling spectroscopy and SQUID, respectively, for a series of 3d transition-metal (Mn, Fe, Co)-doped ZnO. By tunneling spectroscopy an additional density of states was observed in Mn- and Co-doped ZnO adjacent to the top of the valence band of the host ZnO. Instead, in the Fe-doped sample, a band of density of states was observed across the Fermi level in the mid-gap. The magnetization curve (M versus H) obtained by SQUID showed a ferromagnetic hysteresis at room temperature for the Fe-doped sample, whereas for the Mn- and Co-doped samples, the M versus H curve showed only a linear characteristic without hysteresis. From the comparison of the density of states and the magnetization characteristics, it is strongly suggested that the ferromagnetism in Fe-doped ZnO at room temperature originates from the half-filled Fe 3d band in the mid-gap of the host ZnO.

  9. Mixture designs to assess composition-structure-property relationships in SiO?-CaO-ZnO-La?O?-TiO?-MgO-SrO-Na?O glasses: potential materials for embolization.

    Science.gov (United States)

    Kehoe, Sharon; Langman, Maxine; Werner-Zwanziger, Ulli; Abraham, Robert J; Boyd, Daniel

    2013-09-01

    Embolization with micron-sized particulates is widely applied to treat uterine fibroids. The objective of this work was to develop mixture designs to predict materials composition-structure-property relationships for the SiO?-CaO-ZnO-La?O?-TiO?-MgO-SrO-Na?O glass system and compare its fundamental materials properties (density and cytocompatibility), against a state-of-the-art embolic agent (contour polyvinyl alcohol) to assess the potential of these materials for embolization therapies. The glass structures were evaluated using ²?Si MAS NMR to identify chemical shift and line width; the particulate densities were determined using helium pycnometry and the cell viabilities were assessed via MTT assay. ²?Si MAS NMR results indicated peak maxima for each glass in the range of -82.3?ppm to -89.9?ppm; associated with Q² to Q³ units in silicate glasses. All experimental embolic compositions showed enhanced in vitro compatibility in comparison to Contour PVA with the exceptions of ORP9 and ORP11 (containing no TiO?). In this study, optimal compositions for cell viability were obtained for the following compositional ranges: 0.095-0.188?mole fraction ZnO; 0.068-0.159?mole fraction La?O?; 0.545-0.562?mole fraction SiO? and 0.042-0.050?mole fraction TiO?. To ensure ease of producibility in obtaining good melts, a maximum loading of 0.068?mole fraction La?O? is required. This is confirmed by the desirability approach, for which the only experimental composition (ORP5) of the materials evaluated was presented as an optimum composition; combining high cell viability with ease of production (0.188?mole fraction ZnO; 0.068?mole fraction La?O?; 0.562?mole fraction SiO? and 0.042?mole fraction TiO?). PMID:22863846

  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. 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>Isosorbide(exo)SO4Na?IsosorbideendoSO4Na?E8?NMe2O>E7>E6?Glucosyl>E5?Diglyceryl?E4>E3>E2?Isosorbide(exo)>Glyceryl>Isosorbide(endo). 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

  12. Semiconductor alloys - Structural property engineering

    Science.gov (United States)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  13. Structural Analysis of Laplacian Spectral Properties in Complex Electric Grids

    CERN Document Server

    Preciado, Victor M; Verghese, George C

    2011-01-01

    Motivated by recent interest for power grid architectures, we study the relationship between structural features of electrical transmission networks and the behavior of certain dynamical processes taking place in the network. The spectrum of the Laplacian matrix plays a key role in a wide range of networked dynamical problems, from transient stability analysis to distributed control. Using methods from algebraic graph theory and convex optimization, we study the relationship between structural features of the network and spectral properties of the Laplacian matrix. We illustrate our results by studying the influence of structural properties on the Laplacian eigenvalues of the American (western states), Spanish and French high-voltage transmission networks.

  14. Liquid tellurides: Structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Saboungi, M.L.; Fortner, J.; Richardson, J.W. [Argonne National Lab., IL (United States); Petric, A. [McMaster Univ., Hamilton, ON (Canada); Doyle, M. [Northwestern Univ., Evanston, IL (United States). Div. of Educational Programs; Enderby, J.E. [Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.

    1992-10-01

    In this paper a review of the thermodynamic, electrical and structural properties of liquid alkali-tellurium alloys is presented with a special emphasis on the interplay between these properties. The thermodynamic properties indicate ordering of the solutions at compositions corresponding to about 12, 50, and 67 atom% of alkali atoms. The electrical conductivity and thermopower data confirm that these liquids are true semiconductors. The neutron diffraction patterns coupled with the above information indicate that in the case of liquid K{sub 0.12}Te{sub 0.88} the measured structure is dominated by the Te-Te contribution, and is remarkably similar to that of pure liquid tellurium, while the equiatomic alloy K{sub 0.50}Te{sub 0.50} is shown to contain mostly Te pairs which are identified with Zintl ions, Te{sub 2}{sup 2{minus}}.

  15. Liquid tellurides: Structure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Saboungi, M.L.; Fortner, J.; Richardson, J.W. (Argonne National Lab., IL (United States)); Petric, A. (McMaster Univ., Hamilton, ON (Canada)); Doyle, M. (Northwestern Univ., Evanston, IL (United States). Div. of Educational Programs); Enderby, J.E. (Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.)

    1992-10-01

    In this paper a review of the thermodynamic, electrical and structural properties of liquid alkali-tellurium alloys is presented with a special emphasis on the interplay between these properties. The thermodynamic properties indicate ordering of the solutions at compositions corresponding to about 12, 50, and 67 atom% of alkali atoms. The electrical conductivity and thermopower data confirm that these liquids are true semiconductors. The neutron diffraction patterns coupled with the above information indicate that in the case of liquid K[sub 0.12]Te[sub 0.88] the measured structure is dominated by the Te-Te contribution, and is remarkably similar to that of pure liquid tellurium, while the equiatomic alloy K[sub 0.50]Te[sub 0.50] is shown to contain mostly Te pairs which are identified with Zintl ions, Te[sub 2][sup 2[minus

  16. Structural properties of Haeckelite nanotubes

    Science.gov (United States)

    Lambin, Ph; Biró, L. P.

    2003-10-01

    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.

  17. 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

  18. Quantitative Structure-Cytotoxicity Relationship of Oleoylamides.

    Science.gov (United States)

    Sakagami, Hiroshi; Uesawa, Yoshihiro; Ishihara, Mariko; Kagaya, Hajime; Kanamoto, Taisei; Terakubo, Shigemi; Nakashima, Hideki; Takao, Koichi; Sugita, Yoshiaki

    2015-10-01

    Eighteen oleoylamides were subjected to quantitative structure-activity relationship analysis based on their cytotoxicity, tumor selectivity and anti-HIV activity, in order to assess their biological activities. Cytotoxicity against four human oral squamous cell carcinoma (OSCC) cell lines and five human oral normal cells (gingival fibroblast, periodontal ligament fibroblast, pulp cell, oral keratinocyte, primary gingival epithelial cells) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. Tumor-selectivity (TS) was evaluated by the ratio of the mean 50% cytotoxic concentration (CC50) against normal human oral cells to that against OSCC cell lines. Potency-selectivity expression (PSE) was determined by the ratio of TS to CC50 against OSCC. Anti-HIV activity was evaluated by the ratio of CC50 to the concentration leading to 50% cytoprotection from HIV infection (EC50). Physicochemical, structural and quantum-chemical parameters were calculated based on the conformations optimized by the LowModeMD method. Among 18 derivatives, compounds 8: with a catechol group) and 18: with a (2-pyridyl)amino group) had the highest TS. On the other hand, doxorubicin and 5-fluorouracil (5-FU) were more highly cytotoxic to normal epithelial cells, displaying unexpectedly lower TS and PSE values. None of the compounds had anti-HIV activity. Among 330 chemical descriptors, 75, 73 and 19 descriptors significantly correlated to the cytotoxicity to normal and tumor cells, and TS, respectively. Multivariate statistics with chemical descriptors for molecular polarization and hydrophobicity may be useful for the evaluation of cytotoxicity and TS of oleoylamides. PMID:26408695

  19. Structure-properties relationships in polymeric fibres

    OpenAIRE

    Penning, Jan Paul,

    1994-01-01

    Dit proefschrift beschrijft een onderzoek naar de samenhang tussen de struktuur en de mechanische eigenschappen van polymere vezels, met als centrale vraag hoe men deze eigenschappen het best kan beschrijven op grond van de vezelstruktuur en hoe deze struktuur onstaat tijdens de diverse stappen van het bereidingsproces. De aandacht richt zich hierbij voornamelijk op vezels die verkregen zijn door het vanuit oplossing verspinnen van flexibele polymeren. Het grootste deel van het proefschrift h...

  20. Structure-Property Relationships in Polyolefins

    OpenAIRE

    Hedesiu, Cristian Eugen

    2007-01-01

    Änderungen der starren, halbweichen und weichen Fraktion, der Kettendynamik und der Domänengröße von isotaktischem Polypropylen (iPP) wurden in Abhängigkeit der Temperatur, der Lagerungstemperatur sowie -zeit, dem Ziehverhältnis, der dabei herrschenden Temperatur, der Ziehgeschwindigkeit, dem Ethylen-Propylen-Gummi-Gehalt und der Zugabe von Nukleierungsmitteln untersucht. Diese Änderungen wurden mit hoher Empfindlichkeit per Niedrig- und Hochfeld-Festkörper-Kernspinresonanz (NMR), Transmissio...

  1. 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.

  2. Relationships between properties and functional targets of Chinese herbs

    OpenAIRE

    Bin Xiao; Yun Wang

    2011-01-01

    Abstract: Functional targets are the objects that Chinese herbal medicines act directly upon. If the relationships between the properties of Chinese herbs and their functional targets were analyzed clearly, it would benefit the overall understanding of the holistic mechanisms of Chinese herbal treatments. In this paper, data regarding the properties of Chinese herbs and their functional targets were collected from the 2005 edition of The People’s Republic of China Pharmacopoeia. After analyzi...

  3. 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.

  4. Estimation of exposure and ecotoxicity of chemicals by computer based structure-property and structure-activity relationships; Abschaetzung des umweltchemischen und oekotoxikologischen Verhaltens von Stoffen durch computergestuetzte Analyse von Struktur und Verhalten sowie von Struktur und Wirkung

    Energy Technology Data Exchange (ETDEWEB)

    Jaeckel, H. [Fraunhofer-Institut fuer Umweltchemie und Oekotoxikologie, Schmallenberg (Germany); Mueller, M. [Fraunhofer-Institut fuer Umweltchemie und Oekotoxikologie, Schmallenberg (Germany); Nendza, M. [Fraunhofer-Institut fuer Umweltchemie und Oekotoxikologie, Schmallenberg (Germany); Klein, W. [Fraunhofer-Institut fuer Umweltchemie und Oekotoxikologie, Schmallenberg (Germany); Gies-Reuschel, A. [Umweltbundesamt, Berlin (Germany)

    1993-12-31

    Risk assessment of chemicals requires comprehensive data material, which often is not available. To provide substitutes for the lacking experimental ecotoxicological and physico-chemical data, a software-system (SAR-System) has been developed comprising more than 90 estimation models for relevant endpoints. The approach is based on qualitative structure-activity relationships (QSAR). Two major aspects characterize the SAR-System: (1) The implemented models were tested for their validity and application range. (2) The QSARs are accessible by a menu-driven programme package. The following endpoints are included: Physico-chemical Data: 1-Octanol/water-partition-coefficient log P{sub ow}, vapour pressure, water solubility, pK{sub a}-value, boiling point. Biological Data: Toxicity towards fish, daphnia, tetrahymenae, algae, bacteria and mammals, mutagenicity. Distribution: Soil sorption, bioconcentration, Henry-Constant, Mackay (Level I). Degradation: Photodegradation, biodegradability. (orig.) [Deutsch] Die Bewertung von Chemikalien in der Umwelt erfordert eine Vielzahl von haeufig nicht verfuegbaren Stoffdaten. Um experimentelle oekotoxikologische und physikochemische Daten zu ergaenzen, wurde ein Software-System (SAR-System) entwickelt, welches ueber 90 Schaetzverfahren auf der Basis von Quantitativen Struktur-Aktivitaets-Beziehungen (QSAR) enthaelt. Zwei wesentliche Kriterien zeichnen das SAR-System aus: 1) Die implementierten Modelle wurden einer Validierung zur Feststellung des gueltigen Anwendungsbereichs unterzogen. 2) Die Schaetzverfahren sind ueber ein benutzerfreundliches, ausschliesslich menuegesteuertes Programmpaket zugaenglich. Zu folgenden Parametern stehen Schaetzverfahren zur Verfuegung: Physiko-chemische Daten: 1-Octanol/Wasser-Verteilungskoeffizient log P{sub ow}, Dampfdruck, Wasserloeslichkeit, pK{sub a}-Wert, Siedepunkt. Biologische Endpunkte: Toxizitaet gegenueber Fischen, Daphnien, Tetrahymenae, Algen, Bakterien und Saeugetieren, Mutagenitaet. Verteilung: Bodensorption, Biokonzentration, Henry-Konstante, Mackay (Level I). Abbau: Photoabbau, Bioabbaubarkeit. (orig.)

  5. Grain boundary structure and properties

    International Nuclear Information System (INIS)

    An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of our knowledge of these fundamentals is given. Included are the following: (1) structure of ideal perfect boundaries; (2) defect structure of grain boundaries; (3) diffusion at grain boundaries; (4) grain boundaries as sources/sinks for point defects; (5) grain boundary migration; (6) dislocation phenomena at grain boundaries; (7) atomic bonding and cohesion at grain boundaries; (8) non-equilibrium properties of grain boundaries; and (9) techniques for studying grain boundaries

  6. Mereology of Quantitative Structure-Activity Relationships Models

    Directory of Open Access Journals (Sweden)

    Guillermo Restrepo

    2015-12-01

    Full Text Available In continuing with the research program initiated by Llored and Harré of exploring the part/whole (mereological discourses of chemistry, we analyse Quantitative Structure-Activity Relationships (QSAR studies, which are widespread approaches for modeling substances’ properties. The study is carried out by analyzing a particular QSAR model, and it is found that different mereologies are needed: from those regarding bulk substances as wholes and molecular entities as parts and to mereologies where the wholes are molecules whose parts are atoms, structured subsets of atoms, nuclei and electronic densities. We suggest a relationship between successful QSAR models and a deep understanding of the mereologies used and the ways they are intertwined. We note that QSAR modelers prefer the mereology of substance-molecule and then discuss how that is related to simplicity and computational capacity. Historical questions are opened, e.g. how the mereologies of substances have changed over time? and why they are mostly oriented toward organic chemistry?

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

    OpenAIRE

    Ajayi M. T. A.; Ogunbajo A. Rukaiyat; Sule I. Abass; 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 examine ...

  8. Thapsigargin, origin, chemistry, structure-activity relationships and prodrug development.

    DEFF Research Database (Denmark)

    Doan, Thi Quynh Nhu; Christensen, SØren BrØgger

    2015-01-01

    Thapsigargin was originally isolated from the roots of the Mediterranean umbelliferous plant Thapsia garganica in order to characterize the skin irritant principle. The biological activity was related to the subnanomolar affinity for the sarco-endoplasmic reticulum calcium ATPase. Prolonged inhibition of the pump afforded collapse of the calcium homeostasis and eventually apoptosis. Structure-activity relationships enabled design of an equipotent analogue containing a linker. Conjugation of a peptide, which only is a substrate for prostate specific antigen enabled design of a prodrug (G115) targeted against prostate cancer. Conjugation to a peptide, which only is a substrate for prostate specific membrane antigen enabled development of a prodrug (G202), which is targeted towards a number of cancer diseases including hepatocellular carcinoma. G202 has under the name of mipsagargin in clinical trials 2 shown promising properties against hepatocellular carcinoma.

  9. 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

  10. Learning the Structure of Biomedical Relationships from Unstructured Text.

    Science.gov (United States)

    Percha, Bethany; Altman, Russ B

    2015-07-01

    The published biomedical research literature encompasses most of our understanding of how drugs interact with gene products to produce physiological responses (phenotypes). Unfortunately, this information is distributed throughout the unstructured text of over 23 million articles. The creation of structured resources that catalog the relationships between drugs and genes would accelerate the translation of basic molecular knowledge into discoveries of genomic biomarkers for drug response and prediction of unexpected drug-drug interactions. Extracting these relationships from natural language sentences on such a large scale, however, requires text mining algorithms that can recognize when different-looking statements are expressing similar ideas. Here we describe a novel algorithm, Ensemble Biclustering for Classification (EBC), that learns the structure of biomedical relationships automatically from text, overcoming differences in word choice and sentence structure. We validate EBC's performance against manually-curated sets of (1) pharmacogenomic relationships from PharmGKB and (2) drug-target relationships from DrugBank, and use it to discover new drug-gene relationships for both knowledge bases. We then apply EBC to map the complete universe of drug-gene relationships based on their descriptions in Medline, revealing unexpected structure that challenges current notions about how these relationships are expressed in text. For instance, we learn that newer experimental findings are described in consistently different ways than established knowledge, and that seemingly pure classes of relationships can exhibit interesting chimeric structure. The EBC algorithm is flexible and adaptable to a wide range of problems in biomedical text mining. PMID:26219079

  11. Asymptotic Properties of Parameters for Linear Circular Functional Relationship Model

    Directory of Open Access Journals (Sweden)

    A.G. Hussin

    2008-01-01

    Full Text Available This study discusses the asymptotic properties of parameters for unreplicated linear circular functional relationship model. The model is formulated assuming both variables are circular, subject to errors and there is a linear relationship between them. The Maximum Likelihood Estimation (MLE have been used to estimate the slope parameters (β, intercept (α and error concentration parameters for both variables which are κ and v, respectively. The Fisher information matrix have been derived and based on this we estimated the asymptotic covariance matrix of

  12. Elastic properties of chalcopyrite structured solids

    International Nuclear Information System (INIS)

    Highlights: ? In this paper the authors have been evaluated six independent elastic stiffness constants, C11, C12, C13, C22, C33 and C44 for chalcopyrite (AIBIIIC2VI and AIIBIVC2V) structured solids with the help of ionic charge theory. ? The proposed relationship only the kBTm/? normalization and ionic charge are required as input, the computation of elastic constants itself is trivial, and the accuracy of the results compares well with experimental values. ? The method turns out to be widely applicable. - Abstract: Elastic properties (i.e. six independent elastic stiffness constants, C11, C12, C13, C33, C44 and C66) of chalcopyrite structured solids were evaluated. Values of C11, C33, C44, C66, of AIBIIIC2VI and AIIBIVC2V chalcopyrite semiconductors exhibit a linear relationship when plotted against the kBTm/? (kB = Boltzmann's constant, Tm = melting temperature, ? = atomic volume) normalization, but fall on two straight lines according to the product of ionic charges of the compounds. The calculated results are compared with available experimental data and previous calculations based on phenomenological models.

  13. Quantitative structure-activity relationship correlation between molecular structure and the Rayleigh enantiomeric enrichment factor.

    Science.gov (United States)

    Jammer, S; Rizkov, D; Gelman, F; Lev, O

    2015-08-01

    It was recently demonstrated that under environmentally relevant conditions the Rayleigh equation is valid to describe the enantiomeric enrichment - conversion relationship, yielding a proportional constant called the enantiomeric enrichment factor, ?ER. In the present study we demonstrate a quantitative structure-activity relationship model (QSAR) that describes well the dependence of ?ER on molecular structure. The enantiomeric enrichment factor can be predicted by the linear Hansch model, which correlates biological activity with physicochemical properties. Enantioselective hydrolysis of sixteen derivatives of 2-(phenoxy)propionate (PPMs) have been analyzed during enzymatic degradation by lipases from Pseudomonas fluorescens (PFL), Pseudomonas cepacia (PCL), and Candida rugosa (CRL). In all cases the QSAR relationships were significant with R(2) values of 0.90-0.93, and showed high predictive abilities with internal and external validations providing QLOO(2) values of 0.85-0.87 and QExt(2) values of 0.8-0.91. Moreover, it is demonstrated that this model enables differentiation between enzymes with different binding site shapes. The enantioselectivity of PFL and PCL was dictated by electronic properties, whereas the enantioselectivity of CRL was determined by lipophilicity and steric factors. The predictive ability of the QSAR model demonstrated in the present study may serve as a helpful tool in environmental studies, assisting in source tracking of unstudied chiral compounds belonging to a well-studied homologous series. PMID:26153539

  14. Relationship between protein structure and geometrical constraints

    DEFF Research Database (Denmark)

    Lund, Ole; Hansen, Jan; Brunak, Søren; Bohr, Jakob

    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 ef...

  15. Relationship between protein structure and geometrical constrains

    DEFF Research Database (Denmark)

    Lund, Ole; Hansen, Jan; Brunak, Søren; Bohr, Jakob

    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 ef...

  16. Preparation, structure and dielectric property of barium stannate titanate ceramics

    International Nuclear Information System (INIS)

    The processing route of barium stannate titanate ceramics were optimized to prepare full composition range solid solution sample. The phase structure, microscopic morphology and dielectric properties of barium stannate titanate ceramics were studied. X-ray diffraction patterns indicated that the samples are of single perovskite structure. Linear empirical relationship between crystal lattice and tin content was proposed. This relationship is valid covering the full composition range, which suggests that this solid solution system is ultimate mutual soluble. The phase transition behavior was studied and a phase diagram was obtained based on the dielectric measurements

  17. Structure-function relationships in methionine adenosyltransferases

    OpenAIRE

    Markham, George D.; Pajares, María A.

    2009-01-01

    Methionine adenosyltransferases (MAT) are the family of enzymes that synthesize the main biological methyl donor, S-adenosylmethionine. The high sequence conservation among catalytic subunits from bacteria and Eukarya preserves key residues that control activity and oligomerization, which is reflected in the protein structure. However, structural differences among complexes with substrates and products have led to proposals of several reaction mechanisms. In parallel, folding studies are star...

  18. [Psychometric Properties of the Sibling Relationship Questionnaire in the German Version (SRQ-deu)].

    Science.gov (United States)

    Bojanowski, Sabine; Riestock, Nora; Nisslein, Joel; Weschenfelder-Stachwitz, Heike; Lehmkuhl, Ulrike

    2015-09-01

    The present study examines the psychometric properties of the German version of the Sibling Relationship Questionnaire (SRQ-deu, self-rating) in 961 children and adolescents aged 8-18 years. Internal consistency was satisfactory to high. Associations with other clinical instruments point in the expected direction and support the external validity of the SRQ-deu. A confirmatory factor analysis largely supported the 4-factor structure generated by the German version of the SRQ (SRQ-deu). PMID:26039367

  19. 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 ca...

  20. Structure-activity relationships of bumetanide derivatives

    DEFF Research Database (Denmark)

    Pedersen, Kasper Lykke; Töllner, Kathrin; Römermann, Kerstin; Feit, Peter W; Erker, Thomas; MacAulay, Nanna; Löscher, Wolfgang

    2015-01-01

    BACKGROUND AND PURPOSE: The N-K-Cl cotransporters (NKCCs) mediate the coupled, electroneutral movement of Na(+) , K(+) and Cl(-) ions across cell membranes. There are two isoforms of this cation co-transporter, NKCC1 and NKCC2. NKCC2 is expressed primarily in the kidney and is the target of diuretics such as bumetanide. Bumetanide was discovered by screening ?5000 3-amino-5-sulfamoylbenzoic acid derivatives, long before NKCC2 was identified in the kidney. Therefore, structure-activity studies on...

  1. Structure-function relationships in telomerase genes.

    Czech Academy of Sciences Publication Activity Database

    Sýkorová, Eva; Fajkus, Ji?í

    2009-01-01

    Ro?. 101, ?. 7 (2009), s. 375-392. ISSN 0248-4900 R&D Projects: GA AV ?R(CZ) IAA600040505; GA AV ?R(CZ) IAA500040801; GA MŠk(CZ) LC06004 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : telomerase * alternative splicing * gene structure Subject RIV: BO - Biophysics Impact factor: 3.974, year: 2009

  2. Ecto-5’-nucleotidase: Structure function relationships

    OpenAIRE

    Sträter, Norbert

    2006-01-01

    Ecto-5’-nucleotidase (ecto-5’-NT) is attached via a GPI anchor to the extracellular membrane, where it hydrolyses AMP to adenosine and phosphate. Related 5’-nucleotidases exist in bacteria, where they are exported into the periplasmic space. X-ray structures of the 5’-nucleotidase from E. coli showed that the enzyme consists of two domains. The N-terminal domain coordinates two catalytic divalent metal ions, whereas the C-terminal domain provides the substrate specificity pocket for the nucle...

  3. 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.

  4. A structurally-based model of irradiated graphite properties

    Energy Technology Data Exchange (ETDEWEB)

    Bradford, Mark R. [Design Authority, British Energy, Barnett Way, Barnwood, Gloucester GL4 3RS (United Kingdom)], E-mail: mark.r.bradford@british-energy.com; Steer, Alan G. [Design Authority, British Energy, Barnett Way, Barnwood, Gloucester GL4 3RS (United Kingdom)

    2008-10-31

    In this paper, we describe a model of irradiated graphite properties that is based on an understanding of the interconnection of the structure. Simplified conceptual models have enabled us to explain many of the correlations that exist between irradiated graphite material properties and derive mathematical formulations that appear to be of widespread applicability. The principles of the model are illustrated with reference to the irradiation 'structure term' of Young's modulus. It is shown that the currently used definition may be considered to be a combination of three separate processes - pore closure driven densification, increased structural interconnectivity and (latterly) pore generation. It is the structural interconnectivity component that is most closely linked to the changes in other properties such as dimensional change rate and coefficient of thermal expansion, and this relationship is used to direct the mathematical formulations.

  5. The Structure, Functions, and Mechanical Properties of Keratin

    Science.gov (United States)

    McKittrick, J.; Chen, P.-Y.; Bodde, S. G.; Yang, W.; Novitskaya, E. E.; Meyers, M. A.

    2012-04-01

    Keratin is one of the most important structural proteins in nature and is widely found in the integument in vertebrates. It is classified into two types: ?-helices and ?-pleated sheets. Keratinized materials can be considered as fiber-reinforced composites consisting of crystalline intermediate filaments embedded in an amorphous protein matrix. They have a wide variety of morphologies and properties depending on different functions. Here, we review selected keratin-based materials, such as skin, hair, wool, quill, horn, hoof, feather, and beak, focusing on the structure-mechanical property-function relationships and finally give some insights on bioinspired composite design based on keratinized materials.

  6. 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

  7. 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

  8. 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; Mueller-Harvey, Irene; Fryganas, Christos; Thamsborg, Stig Milan

    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 structure and anthelmintic activity using an in vitro assay. We used a series of purified t...

  9. 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.; Mueller-Harvey, I.; Fryganas, C.; M. Thamsborg, S.

    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 pur...

  10. Structure–Function Relationships in Highly Modified Shoots of Cactaceae

    OpenAIRE

    MAUSETH, JAMES D.

    2006-01-01

    • Background and Aims Cacti are extremely diverse structurally and ecologically, and so modified as to be intimidating to many biologists. Yet all have the same organization as most dicots, none differs fundamentally from Arabidopsis or other model plants. This review explains cactus shoot structure, discusses relationships between structure, ecology, development and evolution, and indicates areas where research on cacti is necessary to test general theories of morphogenesis.

  11. Structural and electronic properties of atomic chains

    International Nuclear Information System (INIS)

    Structural and electronic properties of atomic chains are investigated in terms of transfer-matrix-technique within Landauer-model for electrical conductance. The role of structural defects (within deterministic and statistical models) in formation of resistivity and spectral properties is shown. A semi-phenomenological approach to elastic electron scattering on the ad atomic complex is considered. 33 refs.; 4 figs. (author)

  12. Structure-function relationships of immunostimulatory polysaccharides: A review.

    Science.gov (United States)

    Ferreira, Sónia S; Passos, Cláudia P; Madureira, Pedro; Vilanova, Manuel; Coimbra, Manuel A

    2015-11-01

    Immunostimulatory polysaccharides are compounds capable of interacting with the immune system and enhance specific mechanisms of the host response. Glucans, mannans, pectic polysaccharides, arabinogalactans, fucoidans, galactans, hyaluronans, fructans, and xylans are polysaccharides with reported immunostimulatory activity. The structural features that have been related with such activity are the monosaccharide and glycosidic-linkage composition, conformation, molecular weight, functional groups, and branching characteristics. However, the establishment of structure-function relationships is possible only if purified and characterized polysaccharides are used and selective structural modifications performed. Aiming at contributing to the definition of the structure-function relationships necessary to design immunostimulatory polysaccharides with potential for preventive or therapeutical purposes or to be recognized as health-improving ingredients in functional foods, this review introduces basic immunological concepts required to understand the mechanisms that rule the potential claimed immunostimulatory activity of polysaccharides and critically presents a literature survey on the structural features of the polysaccharides and reported immunostimulatory activity. PMID:26256362

  13. 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

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

    DEFF Research Database (Denmark)

    Jensen, Jens Dahl; Pantleon, Karen; Somers, Marcel A.J.

    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 atomi...

  15. 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)

  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. Mechanical properties and structure of austempered ductile iron -ADI

    OpenAIRE

    Krzy?ska A.; Kaczorowaki M.

    2007-01-01

    The results of experimental study of austempered ductile iron are presented. The aim of the investigations was to look closer into the structure – mechanical properties relationships of this very attractive cast material. The experiment was carried out with 500 7 grade ductile iron, which was austempered using different parameters of heat treatment. The specimens were first solution treated 1 hour in 910oC and then isothermally quenched for different time in silicon oil bath of temperature 27...

  18. Structural properties of semenogelin I.

    OpenAIRE

    Malm, Johan; Jonsson, Magnus; Frohm, Birgitta; Linse, Sara

    2007-01-01

    The zinc-binding protein semenogelin I is the major structural component of the gelatinous coagulum that is formed in freshly ejaculated semen. Semenogelin I is a rapidly evolving protein with a primary structure that consists of six repetitive units, each comprising approximately 60 amino acid residues. We studied the secondary and tertiary structure of semenogelin I by circular dichroism (CD) spectroscopy and Trp fluorescence emission spectroscopy. Fitting to the far-UV CD data indicated th...

  19. Exploring structure-function relationships between TRP and Kv channels

    OpenAIRE

    Kalia, Jeet; Swartz, Kenton J.

    2013-01-01

    The molecular mechanisms underlying the activation of Transient Receptor Potential (TRP) ion channels are poorly understood when compared to those of the voltage-activated potassium (Kv) channels. The architectural and pharmacological similarities between the members of these two families of channels suggest that their structure-function relationships may have common features. We explored this hypothesis by replacing previously identified domains and critical structural motifs of the membrane...

  20. Numerical calculations of effective elastic properties of two cellular structures

    International Nuclear Information System (INIS)

    Young's moduli of regular two-dimensional truss-like and eye-shaped structures are simulated using the finite element method. The structures are idealizations of soft polymeric materials used in ferro-electret applications. In the simulations, the length scales of the smallest representative units are varied, which changes the dimensions of the cell walls in the structures. A power-law expression with a quadratic as the exponent term is proposed for the effective Young's moduli of the systems as a function of the solid volume fraction. The data are divided into three regions with respect to the volume fraction: low, intermediate and high. The parameters of the proposed power-law expression in each region are later represented as a function of the structural parameters, the unit-cell dimensions. The expression presented can be used to predict a structure/property relationship in materials with similar cellular structures. The contribution of the cell-wall thickness to the elastic properties becomes significant at concentrations >0.15. The cell-wall thickness is the most significant factor in predicting the effective Young's modulus of regular cellular structures at high volume fractions of solid. At lower concentrations of solid, the eye-shaped structure yields a lower Young's modulus than a truss-like structure with similar anisotropy. Comparison of the numerical results with those of experimental data for poly(propylene) show good agreement regarding the influence of cell-wall thickness on elastic properties of thin cellular films

  1. Structural Diversity and Close Interracial Relationships in College

    Science.gov (United States)

    Bowman, Nicholas A.

    2012-01-01

    Recent legal and political actions have challenged the use of race-conscious college admissions policies. Earlier research offers mixed evidence about the link between an institution's racial/ethnic composition (i.e., structural diversity) and the formation of close interracial relationships, so the present study examines this topic directly for…

  2. 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)

  3. Nicotinamide Phosphoribosyltransferase Inhibitors, Design, Preparation, and Structure-Activity Relationship

    DEFF Research Database (Denmark)

    Christensen, Mette K; Erichsen, Kamille D; Høgh Olesen, Uffe; Tjørnelund, Jette; Fristrup, Peter; Thougaard, Annemette; Nielsen, Søren Jensby; Sehested, Maxwell; Jensen, Peter B; Loza, Einars; Kalvinsh, Ivars; Garten, Antje; Kiess, Wieland; Björkling, Fredrik

    2013-01-01

    Existing pharmacological inhibitors for nicotinamide phosphoribosyltransferase (NAMPT) are promising therapeutics for treating cancer. By using medicinal and computational chemistry methods, the structure-activity relationship for novel classes of NAMPT inhibitors is described, and the compounds are optimized. Compounds are designed inspired by the NAMPT inhibitor APO866 and cyanoguanidine inhibitor scaffolds. In comparison with recently published derivatives, the new analogues exhibit an equall...

  4. The relationship between administration forms, creativity management and organization structures

    OpenAIRE

    Iraz, Rifat; Gok, Suudan Gokce

    2014-01-01

       Today,   managing   creativity   is   an   obligation   for   contemporary   companies  for   preventing   their   competitive   position.   Creativity   management,   as   a  technic  of  human  resource  management  demands  continuous,  integrated  and   systematic   applications   The   purpose   of   this   study   is   to   uncover   the  relationship   between   administration   forms,   creativity   management   and  organization  structures.  In  this  context,  a  questionnaire  ...

  5. 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…

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

    Science.gov (United States)

    Tiley, Jaimie Scott

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

  7. Application of the rough sets theory in structure activity relationship of antielectrostatic ammonium compounds.

    Science.gov (United States)

    Krysi?ski, Jerzy; Skrzypczak, Andrzej; Demski, Grzegorz

    2003-01-01

    The relationships between the chemical structure and the antielectrostatic effect of 112 ammonium compounds were analysed using the method of rough sets. The antielectrostatic activity was determined by measurements of the maximum voltage induced. Using the rough sets approach the smallest set of condition attributes significant for high quality of classification has been found. The resulting decision rules describe relations between the structure and the antielectrostatic properties of ammonium chlorides in terms of significant condition attributes. This may be helpful in predicting the structures of the new antielectrostatic compounds to be synthesized. PMID:13678321

  8. 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

  9. 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.

  10. Alternating and direct current field effects on the structure-property relationships in Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-x%BaTiO{sub 3} textured ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Wenwei; Li, Jiefang; Viehland, D. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Maurya, Deepam; Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2013-06-03

    The influence of alternating (ac) and direct current (dc) fields on the structural and dielectric properties of [001]{sub PC} textured Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} (NBT-7%BT) ceramics has been investigated. X-ray diffraction measurements revealed that the depolarization at temperature T{sub d} in poled samples resulted from a tetragonal {yields} pseudo-cubic transition on heating. Moderate ac drive and dc bias had opposite influences on T{sub d}: ac drive decreased the T{sub d}, whereas dc bias increased it. These investigations suggested an effective method to expand the working temperature range of NBT-x%BT textured ceramics to a high temperature.

  11. Alternating and direct current field effects on the structure-property relationships in Na0.5Bi0.5TiO3-x%BaTiO3 textured ceramics

    Science.gov (United States)

    Ge, Wenwei; Maurya, Deepam; Li, Jiefang; Priya, Shashank; Viehland, D.

    2013-06-01

    The influence of alternating (ac) and direct current (dc) fields on the structural and dielectric properties of [001]PC textured Na0.5Bi0.5TiO3-7%BaTiO3 (NBT-7%BT) ceramics has been investigated. X-ray diffraction measurements revealed that the depolarization at temperature Td in poled samples resulted from a tetragonal ? pseudo-cubic transition on heating. Moderate ac drive and dc bias had opposite influences on Td: ac drive decreased the Td, whereas dc bias increased it. These investigations suggested an effective method to expand the working temperature range of NBT-x%BT textured ceramics to a high temperature.

  12. Relationships between the structural properties and the superconductivity in Y0.4Pr0.6Ba2-xSrxCu3O7-? (x=0, 1.0)

    International Nuclear Information System (INIS)

    The Y0.4Pr0.6Ba2-xSrxCu3O7-? (x=0, 1.0) samples were prepared and the structural properties were studied by X-ray Rietveld analysis. It has been found that the average Pr-O bond length increases from 2.435 A at x=0 to 2.457 A at x=1.0, the Cu(2)-O-Cu(2) angles within the CuO2 planes become larger, and there is no significant mutual substitution between Pr and Sr ions. The BVS calculation suggests that Sr doping brings about the increase of the hole concentration on CuO2 planes and the weakening of Pr-O covalent mixing. Our work supports that Pr-O covalent mixing effect is responsible for the superconductivity suppression by Pr. (orig.)

  13. 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.

  14. Enhanced Small Molecule Similarity for Quantitative Structure-Activity Relationship Modeling and Cheminformatics Applications

    OpenAIRE

    Girschick, Tobias

    2014-01-01

    This thesis introduces concepts for the enhancement of the calculation and application of small molecule similarity as it is used in the pharmaceutical and chemical industry. The main focus is on machine learning as well as data mining approaches used for the prediction of properties of uncharacterized molecules and for database similarity searches. The work shows how (quantitative) structure-activity relationships can be improved using enhanced small molecule similarity concepts.

  15. Relationship between oxygen chemical potential, annealing conditions, and superconducting properties of YBa2Cu3Ox

    International Nuclear Information System (INIS)

    A strong relationship between superconducting properties, oxygen chemical potential, and heat treatment during preparation of YBa2Cu3Ox is investigated. Resistivity measurements as a function of temperature, isochoric solid-gas equilibrium determination, and thermogravimetric studies under different gas atmospheres were carried out. The results can be explained either by a quasi-binary solid solution of oxygen in YBa2Cu3Ox or by a coexistence of two ternary solid solutions of different structures. There is a high mobility of oxygen in the lattice and superconductivity is very sensitive to small changes in the oxygen occupation ?x

  16. Evaluation of Relationship Between Mechanical Properties of High Strength Self Compacting Concrete

    Directory of Open Access Journals (Sweden)

    S.SeshaPhani

    2013-01-01

    Full Text Available In the present experimental investigation an attempt is made to report relationship between compressive strength , Split tensile Strength and Flexural Strength of High Strength Self Compacting Concrete with mineral admixtures . It is well known that the properties of concrete are affected by cementitious matrix,aggregate and the transition zone between the two phases. Reducing water powder ratio and addition of pozollona admixtures like Fly ash and Micro silica are often used to modify the micro structure of the matrix and to optimize the transition zone.

  17. Characterization of the structure-function relationship at the ligament-to-bone interface.

    Science.gov (United States)

    Moffat, Kristen L; Sun, Wan-Hsuan S; Pena, Paul E; Chahine, Nadeen O; Doty, Stephen B; Ateshian, Gerard A; Hung, Clark T; Lu, Helen H

    2008-06-10

    Soft tissues such as ligaments and tendons integrate with bone through a fibrocartilaginous interface divided into noncalcified and calcified regions. This junction between distinct tissue types is frequently injured and not reestablished after surgical repair. Its regeneration is also limited by a lack of understanding of the structure-function relationship inherent at this complex interface. Therefore, focusing on the insertion site between the anterior cruciate ligament (ACL) and bone, the objectives of this study are: (i) to determine interface compressive mechanical properties, (ii) to characterize interface mineral presence and distribution, and (iii) to evaluate insertion site-dependent changes in mechanical properties and matrix mineral content. Interface mechanical properties were determined by coupling microcompression with optimized digital image correlation analysis, whereas mineral presence and distribution were characterized by energy dispersive x-ray analysis and backscattered scanning electron microscopy. Both region- and insertion-dependent changes in mechanical properties were found, with the calcified interface region exhibiting significantly greater compressive mechanical properties than the noncalcified region. Mineral presence was only detectable within the calcified interface and bone regions, and its distribution corresponds to region-dependent mechanical inhomogeneity. Additionally, the compressive mechanical properties of the tibial insertion were greater than those of the femoral. The interface structure-function relationship elucidated in this study provides critical insight for interface regeneration and the formation of complex tissue systems. PMID:18541916

  18. Correlation of Local Structure and Electronic Properties of Glass Materials

    Science.gov (United States)

    Lordi, Vincenzo; Adelstein, Nicole

    2015-03-01

    Wide band gap glasses such as silica and its derivatives are typically considered insulators. However, electronic transport in glasses can be important for certain applications, such as when used as the host material for a scintillator radiation detector. Here we explore the relationship between local structure in glass materials and the corresponding electronic properties of carrier transport and charge trapping. We present a novel analysis that decomposes the distribution of localized band tail states in terms of specific local structural features in the glass. Comparison of the structure-related transport properties of different glass compositions is given, using silica and sodium silicate as prototypes. Prepared by LLNL under Contract DE-AC52-07NA27344.

  19. Structural properties of screened Coulomb balls

    CERN Document Server

    Bonitz, M; Arp, O; Golubnychiy, V; Baumgartner, H; Ludwig, P; Piel, A; Filinov, A

    2005-01-01

    Small three-dimensional strongly coupled charged particles in a spherical confinement potential arrange themselves in a nested shell structure. By means of experiments, computer simulations and theoretical analysis, it is shown that their structural properties depend on the type of interparticle forces. Using an isotropic Yukawa interaction, quantitative agreement for shell radii and occupation is obtained.

  20. Grain boundary structure and properties

    International Nuclear Information System (INIS)

    An attempt is made to distinguish those fundamental aspects of grain boundaries which should be relevant to the problem of the time dependent fracture of high temperature structural materials. These include the basic phenomena which are thought to be associated with cavitation and cracking at grain boundaries during service and with the more general microstructural changes which occur during both processing and service. A very brief discussion of the current state of knowledge of these fundamentals is given

  1. 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...

  2. 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.

  3. 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

  4. Finite Element Estimation of Meteorite Structural Properties

    Science.gov (United States)

    Hart, Kenneth Arthur

    2015-01-01

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

  5. Thapsigargin, origin, chemistry, structure-activity relationships and prodrug development

    DEFF Research Database (Denmark)

    Doan, Thi Quynh Nhu; Christensen, Søren Brøgger

    2015-01-01

    Thapsigargin was originally isolated from the roots of the Mediterranean umbelliferous plant Thapsia garganica in order to characterize the skin irritant principle. The biological activity was related to the subnanomolar affinity for the sarco-endoplasmic reticulum calcium ATPase. Prolonged inhibition of the pump afforded collapse of the calcium homeostasis and eventually apoptosis. Structure-activity relationships enabled design of an equipotent analogue containing a linker. Conjugation of a pe...

  6. 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 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)

  7. 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

  8. 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.

  9. Sintering and microstructure property relationships of porous hydroxyapatite

    Science.gov (United States)

    Zakaria, Fadzil Ayad

    2000-09-01

    The use of ceramics inside the body, as implant materials, is a relatively new technology, the first instance having been reported just 20 years ago. The ceramics used for the repair and reconstruction of diseased, damaged or 'worn out' parts of the body are referred to as bioceramics, and such a material is hydroxyapatite. The use of calcium phosphate to repair bone defects has been based on the rationale that calcium phosphate resembles vertebrate tooth and bone mineral, and is biologically compatible with these and surrounding tissues. The concept of preparing porous hydroxyapatite was developed to prevent loosening of implants by enhancing the ingrowth of tissue into the pores (biological fixation). A structural limitation of this type of implant is the requirement to have a minimal pore size between 80- 100 m in diameter to allow bone to grow into the pores. The presence of such porosity would lead to a lower strength of the bioceramic component, but this is offset by the advantages of biocompatibility. It is well known that hydroxyapatite is a brittle material and making it porous would reduce the existing mechanical properties. This study was carried out to optimise the mechanical properties by investigating the processing conditions and methods of preparation. The effect of forming method, pore geometry, pore size, sintering cycle, sintering atmosphere and types of spherical polymers on the microstructure and mechanical properties were studied. As a consequence of the experiments, it was observed that porous hydroxyapatite is formed using an isostatic pressing technique, with 53 vol. % of HMWPVC as the porosifier. Sintering in air, with a heating rate of 50C/h, held for 1h at 600C in the first stage, and a heating rate of 100C/h, held for 4h at between 1200 and 1250C, generated a spherical pore geometry which gave the best combination of properties. This fabrication route resulted in an interconnected porous hydroxyapatite with a pore size ~90 m, the volume fraction of porosity ~35%, relative density of ~60%, a grain size ~1.7-2 m, a compressive strength between 14-18 MPa and a tensile strength of 4-5 MPa.

  10. Structural properties of the Hugoniot curve

    International Nuclear Information System (INIS)

    This report is devoted to the structural properties analysis of the HUGONIOT curve, independently of the equation of state (E 0 S) display. The general properties so coming out are applied to the shock waves interacting studies. When phase transitions are present we investigate the splitting of shock waves and also the rarefaction waves. To end with, we present the shock instabilities and the non-uniqueness of solutions when specific E 0 S are present. (author)

  11. Electronic structure and magnetic properties of actinides

    International Nuclear Information System (INIS)

    The study of the actinide series shows the change between transition metal behavior and lanthanide behavior, between constant weak paramagnetism for thorium and strong Curie-Weiss paramagnetism for curium. Curium is shown to be the first metal of the actinide series to be magnetically ordered, its Neel temperature being 52K. The magnetic properties of the actinides depending on all the peripheral electrons, their electronic structure was studied and an attempt was made to determine it by means of a phenomenological model. Attempts were also made to interrelate the different physical properties which depend on the outer electronic structure

  12. Correlated structure-optical properties studies of plasmonic nanoparticles

    International Nuclear Information System (INIS)

    Interest in nanotechnology is driven by unprecedented means to tailor the physical behaviour via structure and composition. Unlike bulk materials, minute changes in size and shape can affect the optical properties of nanoparticles. Characterization, understanding, and prediction of such structure-function relationships is crucial to the development of novel applications such as plasmonic sensors, devices, and drug delivery systems. Such knowledge has been recently vastly expanded through systematic, high throughput correlated measurements, where the localized surface plasmon resonance (LSPR) is probed optically and the particle shape investigated with electron microscopy. This paper will address some of the recent experimental advances in single particle studies that provide new insight not only on the effects of size, composition, and shape on plasmonic properties but also their interrelation. Plasmon resonance frequency and decay, substrate effects, size, shape, and composition will be explored for a variety of plasmonic systems

  13. Contenido de fenoles solubles e insolubles en las estructuras del grano de maíz y su relación con propiedades físicas / Content of soluble and insoluble phenols in the structures of corn grain and their relationship with physical properties

    Scientific Electronic Library Online (English)

    M. Luisa, Cabrera-Soto; Yolanda, Salinas-Moreno; Gustavo A., Velázquez-Cardelas; Edgar, Espinosa Trujillo.

    2009-12-01

    Full Text Available El estudio de los compuestos fenólicos es importante por las funciones de algunos de ellos en los mecanismos de defensa de la planta contra el ataque de patógenos, así como por sus propiedades antioxidantes, antimutagénicas y anticancerígenas. Los objetivos de este trabajo fueron determinar el conte [...] nido de fenoles solubles (FS) e insolubles (FI) en el pericarpio, endospermo y germen del grano de maíz (Zea mays) y su correlación con las propiedades físicas del grano. Se trabajó con dos genotipos experimentales (HE y H-161) cultivados en diferentes localidades y tres maíces comerciales (Oso, Sable y Leopardo). Se analizaron los FS (libres, glucosilados y esterificados) y FI mediante el método de Folin-Ciocalteu. Las variables físicas del grano fueron: peso hectolítrico (PH), índice de flotación (IF), color de grano (CG) y peso de 100 granos (PCG). El contenido de FS fue más elevado en el germen, seguido del pericarpio y endospermo. Dentro de este tipo de fenoles, en las tres estructuras dominaron los fenoles libres. El mayor contenido de FI se presentó en el pericarpio, seguido del germen y endospermo. Existió diferencia estadística (p Abstract in english The study of phenolic compounds is important for the functions of some of them in plant defense mechanisms plant against pathogen attack and by its antioxidant, antimutagenic and anticarcinogenic properties. The objectives of this study were to determine soluble phenol content (FS) and insoluble (FI [...] ) in the pericarp, endosperm and germ of the corn grain (Zea mays) and its correlation with the physical properties of the grain. This work was done with two experimental genotypes (H and H-161) grown in different locations and three commercial maizes (Oso, Sable and Leopardo). The FS were analyzed (free, glycosylated and esterified) as well as FI using the method of Folin-Ciocalteu. The physical variables of the grain were: hectolitric weight (PH), flotation index (FI), grain color (CG) and weight of 100 grains (PCG). The content of FS was higher in the germ, followed by the pericarp and endosperm. Within this type of phenols, free phenols prevailed in the three structures. The highest content of FI was found in the pericarp, followed by the germ and endosperm. There was statistical difference (p

  14. Relationship between radiation interception and photosynthesis in forest canopies: effect of stand structure and latitude

    International Nuclear Information System (INIS)

    Interception of radiation and the consequent potential photosynthesis was studied, by sing a simulation model, in structurally different forest stands at latitudes 40° and 60°. The studied stands were of two different types with respect to the leaf-area distribution: horizontally homogenous canopies and canopies with an aggregation of leaves into individual crowns. The effect of canopy structure on interception of radiation and photosynthesis was studied by varying leaf area index, stand density, and crown size and shape. In none of the studied cases was the relationship between accumulated radiation interception and photosynthesis strictly linear, but on a longer time-scale (one growing season) this non-linearity was not very pronounced. Neither canopy structure nor latitude substantially affected the slope of the relationship. In conclusion, while properties of canopy structure and incoming radiation determine the actual amount of radiation intercepted by the canopy, the conversion efficiency between intercepted radiation and photosynthesis appeared to be rather insensitive to differences in canopy structure and in properties of incoming radiation. (author)

  15. 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.

  16. 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.

  17. Semiconducting clathrates: synthesis, structure and properties

    International Nuclear Information System (INIS)

    The review surveys different aspects of chemical studies of semiconducting clathrates belonging to a unique family of inclusion compounds. The classification, crystal and electronic structures, properties and methods for the synthesis of semiconducting clathrates are considered on the basis of analysis of recent publications. The prospects for fundamental research and the construction of new-generation materials based on semiconducting clathrates are discussed.

  18. 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.

  19. 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

  20. Structure-antioxidant relationship of flavonoids from fermented rooibos.

    Science.gov (United States)

    Krafczyk, Nicole; Woyand, Franziska; Glomb, Marcus A

    2009-05-01

    Rooibos tea (Aspalathus linearis) contains different bioactive phenolic compounds such as dihydrochalcones, flavonols, flavanones, flavones, and flavanols. Flavonoids isolated from rooibos were subjected to different in vitro assays: Trolox equivalent antioxidant activity, LDL oxidation and Fremy's salt assays to determine the total antioxidant activity (TAA). Assay results were compared, and the structure-antioxidant relationship was investigated. A decoupled LDL oxidation test was established with the objective of having an assay adapted more to an in vivo situation. The different in vitro methods were coupled offline to HPLC-DAD. Results from these coupled offline methods were compared to the TAA to assess the usefulness of the coupling setup. PMID:19156714

  1. 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.

  2. 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

  3. Defect structure and thermodynamic properties of nonstoichiometric vanadium monoxide

    International Nuclear Information System (INIS)

    The relationship between the defect structure of oxides in the homogeneity region of VO and their thermodynamic properties has been established. The energy of the formation and interaction of defects responsible for the existence of VO has been determined. Possible ordering of the defect arrangement in VO in a wide temperature range has been elucidated. Seven zones of VO homogeneity have been considered according to the nature of ? anti Ssub o2)sup(0)/? anti H sub(o2)sup(0)/. The energy characteristics of the defects (kcal) have been determined on the basis of the found relationships for three temperature values in therange 1173-1373 deg K..It has been conluded that in the middle part of the homogeneity region of VO considerable attraction of opposite defects can lead to the formation of the complexes of the defects; at temperatures lower than considered an individual phase, similar in composition to VO, may be formed

  4. 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.

  5. 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

  6. 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.)

  7. Electronic and structural properties of complex oxides

    Science.gov (United States)

    Christie, Diane Marie

    This thesis focuses on oxides whose crystalline forms are isomorphic with silica (SiO2) in order to understand their electronic and structural properties. Silica is one of the most widely investigated oxides due to its important electronic, geophysical arid chemical properties. As many as 40 crystalline polymorphs along with amorphous and liquid forms have been described and studied in the literature. The alpha-quartz structure of silica exhibits interesting mechanical and pressure induced behavior. For example, when it is subjected to pressure, it will undergo a slow amorphization. There are many materials that are isostructural with SiO2. Isostructural materials should have similar properties and exhibit similar characteristics. Here we examine three materials: AlPO4, GaAsO4 and GeO 2. AlPO4 has attracted considerable attention owing to the potential technological importance of its high pressure behavior as a memory glass. GaAsO4 is another III-V analog compound, but shows no evidence of pressure induced amorphization as quartz does. GeO2, like silica, undergoes pressure induced amorphization in the alpha-quartz structure, but unlike silica, occurs only in two stable polymorphs. The objective of this thesis is to present a comprehensive picture of oxides that are isostructural with silica. We have computed a variety of properties of each material: (1) Equation of state in the form of volume versus pressure, (2) Structural properties as a function of pressure such as lattice constants and the internal coordinates describing the positions of constituent atoms within the cell, (3) Elastic properties such as the bulk modulus, (4) Electronic properties such as density of states, band structure, and charge density. Computations were performed using a quantum mechanical method based on "soft" ab initio pseudopotentials constructed within a local density approximation. The pseudopotentials required can be extracted from atomic structure calculations. A key element of the pseudopotential includes the elimination of chemically inert states, i.e., the core states. The resulting pseudopotential is weak and the wavefunctions can be described by simple basis sets such as plane waves. This approach is attractive for its reliability and its high predictive power.

  8. Short range ordering and microstructure property relationship in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shariq, A.

    2006-07-01

    A novel algorithm, ''Next Neighbourhood Evaluation (NNE)'', is enunciated during the course of this work, to elucidate the next neighbourhood atomic vicinity from the data, analysed using tomographic atom probe (TAP) that allows specifying atom positions and chemical identities of the next neighbouring atoms for multicomponent amorphous materials in real space. The NNE of the Pd{sub 55}Cu{sub 23}P{sub 22} bulk amorphous alloy reveals that the Pd atoms have the highest probability to be the next neighbours to each other. Moreover, P-P correlation corroborates earlier investigations with scattering techniques that P is not a direct next neighbour to another P atom. Analogous investigations on the Fe{sub 40}Ni{sub 40}B{sub 20} metallic glass ribbons, in the as quenched state and for a state heat treated at 350 C for 1 hour insinuate a pronounced elemental inhomogeneity for the annealed state, though, it also depicts glimpse of a slight inhomogeneity for B distribution even for the as quenched sample. Moreover, a comprehensive microstructural investigation has been carried out on the Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy system. TEM and TAP investigations evince that the as cast bulk samples constitutes a composite structure of an amorphous phase and crystalline phase(s). The crystallization is essentially triggered at the mould walls due to heterogeneous nucleation. The three dimensional atomic reconstruction maps of the volume analysed by TAP reveal a complex stereological interconnected network of two phases. The phase that is rich in Zr and Al concentration is depleted in Co concentration while the phase that is rich in Co concentration is depleted both in Zr and Al. Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy splat samples exhibit a single exothermic crystallization peak contrary to the as cast bulk sample with a different T{sub g} temperature. A single homogeneous amorphous phase revealed by TEM investigations depicts that the faster cooling rate during splat quenching is sufficient for the vitrification of this alloy system. Zr{sub 53}Co{sub 23.5}Al{sub 23.5} bulk samples and splat samples, both exhibit very soft ferromagnetic properties. The heat treatment of as cast bulk sample results in an increase in net magnetization. The crystallization kinetics during the heat treatment, effects both the remanent magnetization, M{sub r} and coercivity, H{sub c} accordingly. Intriguingly, a salient increase in soft ferromagnetic properties is recorded for the heat treated splat samples. (orig.)

  9. Structural properties of small rhodium clusters

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-24

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

  10. 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

  11. 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.

  12. 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)

  13. 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

  14. Structure and Frictional Properties of Colloid Gel

    Directory of Open Access Journals (Sweden)

    Masayuki Tokita

    2014-03-01

    Full Text Available Polymer gels are known to be opaque when the preparation conditions, such as the reaction temperature and the composition, are changed. The increase of the opaqueness of the gel suggests strongly the change of network structure. Here, we are going to review the recent studies on the structure and the frictional study of the opaque poly(acrylamide gel. The results indicate that the opaque poly(acrylamide gel consists of the fractal aggregate of the colloidal particles of sub-micrometer in size. The density of the colloid particle is calculated from the structural parameters and is found to be of the order of about 1 g/cm3. The results indicate that the main chain component and the cross-linker is densely cross-linked into the particle. The frictional property of poly(acrylamide gel is analyzed in terms of the structural parameters of the gel. It is found that the frictional property of the opaque gel is well explained in terms of the structural parameters of the opaque gel.

  15. The structural acoustic properties of stiffened shells

    DEFF Research Database (Denmark)

    Luan, Yu

    2008-01-01

    Plates stiffened with ribs can be modeled as homogeneous isotropic or orthotropic plates, and modeling such an equivalent plate numerically with, say, the finite element method is, of course, far more economical in terms of computer resources than modelling the complete, stiffened plate. This is important when a number of stiffened plates are combined in a complicated structure composed of many plates. However, whereas the equivalent plate theory is well established there is no similar established theory for stiffened shells. This paper investigates the mechanical and structural acoustic properties of curved shells with stiffening ribs. Finite element simulations and experimental data will be compared and discussed.

  16. Structure and electronic properties of amino acid ionic liquids.

    Science.gov (United States)

    Mohajeri, Afshan; Ashrafi, Abolfazl

    2011-06-23

    The interactions between eight amino acid based anions and four imidazolium-based cations have been investigated by density functional theory. The electronic and structural properties of the resulting amino acid ionic liquids (AAILs) have been unveiled by means of the atoms in molecules framework. The calculated interaction energy was found to increase in magnitude with decreasing alkyl chain length at imidazolium ring. Moreover, AAILs composed of an amino acid with some functional group such as aromatic ring had decreased interaction energy. Finally, several correlative relationships between glass transition temperature and interaction energy as well as density at bond critical point have been checked for 1-ethyl-3-methylimidazolium based ILs. Although the obtained correlations do not show excellent fits, a preliminary estimation of the glass transition temperature of different AAILs can be achieved by use of their electronic properties. PMID:21615160

  17. Numerical calculations of effective elastic properties of two cellular structures

    CERN Document Server

    Tuncer, E

    2004-01-01

    Young's moduli of regular two-dimensional truss-like and eye-shape-like structures are simulated by using the finite element method. The structures are the idealizations of soft polymeric materials used in the electret applications. In the simulations size of the representative smallest units are varied, which changes the dimensions of the cell-walls in the structures. A power-law expression with a quadratic as the exponential term is proposed for the effective Young's moduli of the systems as a function of the solid volume fraction. The data is divided into three regions with respect to the volume fraction; low, intermediate and high concentrations. The parameters of the proposed power-law expression in each region are later represented as a function of the structural parameters, unit-cell dimensions. The presented expression can be used to predict structure/property relationship in materials with similar cellular structures. It is observed that the structures with volume fractions of solid higher than 0.15 ...

  18. 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.

  19. Structure and properties of small sodium clusters

    OpenAIRE

    Solov'yov, Ilia A.; Solov'yov, Andrey V.; Greiner, Walter

    2001-01-01

    We have investigated structure and properties of small metal clusters using all-electron ab initio theoretical methods based on the Hartree-Fock approximation and density functional theory, perturbation theory and compared results of our calculations with the available experimental data and the results of other theoretical works. We have systematically calculated the optimized geometries of neutral and singly charged sodium clusters having up to 20 atoms, their multipole mom...

  20. 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.

  1. Relationship between electronic properties and drug activity of seven quinoxaline compounds: A DFT study

    Science.gov (United States)

    Behzadi, Hadi; Roonasi, Payman; Assle taghipour, Khatoon; van der Spoel, David; Manzetti, Sergio

    2015-07-01

    The quantum chemical calculations at the DFT/B3LYP level of theory were carried out on seven quinoxaline compounds, which have been synthesized as anti-Mycobacterium tuberculosis agents. Three conformers were optimized for each compound and the lowest energy structure was found and used in further calculations. The electronic properties including EHOMO, ELUMO and related parameters as well as electron density around oxygen and nitrogen atoms were calculated for each compound. The relationship between the calculated electronic parameters and biological activity of the studied compounds were investigated. Six similar quinoxaline derivatives with possible more drug activity were suggested based on the calculated electronic descriptors. A mechanism was proposed and discussed based on the calculated electronic parameters and bond dissociation energies.

  2. Protein structure. Direct observation of structure-function relationship in a nucleic acid-processing enzyme.

    Science.gov (United States)

    Comstock, Matthew J; Whitley, Kevin D; Jia, Haifeng; Sokoloski, Joshua; Lohman, Timothy M; Ha, Taekjip; Chemla, Yann R

    2015-04-17

    The relationship between protein three-dimensional structure and function is essential for mechanism determination. Unfortunately, most techniques do not provide a direct measurement of this relationship. Structural data are typically limited to static pictures, and function must be inferred. Conversely, functional assays usually provide little information on structural conformation. We developed a single-molecule technique combining optical tweezers and fluorescence microscopy that allows for both measurements simultaneously. Here we present measurements of UvrD, a DNA repair helicase, that directly and unambiguously reveal the connection between its structure and function. Our data reveal that UvrD exhibits two distinct types of unwinding activity regulated by its stoichiometry. Furthermore, two UvrD conformational states, termed "closed" and "open," correlate with movement toward or away from the DNA fork. PMID:25883359

  3. Relationship between molecular structure and Raman spectra of quinolines

    Science.gov (United States)

    Frosch, Torsten; Popp, Jürgen

    2009-04-01

    DFT calculations were applied to investigate the relationship between the molecular structure and the Raman spectra of quinolines. A variety of different quinolines with increasing complexity was investigated and an aminoquinoline nucleus was found that describes the Raman spectrum of protonated chloroquine. It was discovered that the biological important, rigid C7-chloro group and C4-side chain of chloroquine significantly disturb certain molecular vibrations. The protonation at the N1 position causes dramatic changes of the Raman bands in the wavenumber region between 1500 cm -1 and 1650 cm -1. These bands are putative marker bands of the aminoquinoline drugs for ?-? interactions to the hematin targets in malaria infected cells. The calculation of the normal modes and the illustration of the associated atomic displacements are very valuable for a deeper understanding of the associated bands in the Raman spectra.

  4. 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

    OpenAIRE

    Saldana D.A.; Creton B.; Mougin P.; Jeuland N.; Rousseau B.; Starck L.

    2013-01-01

    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...

  5. Structural characterization and pharmaceutical properties of porphyran

    Directory of Open Access Journals (Sweden)

    Saurabh Bhatia

    2015-01-01

    Full Text Available Marine polysaccharides remain an untapped reservoir for development of novel biomaterials. Algae derived sulfated polysaccharides (SPs have their interesting pharmaceutical and biological properties. Degree and pattern of sulfation of such biopolymers favors their binding property with tissues when compared with non-SPs. Due to the gel formation potential, hydrocolloids such as agar, carrageenan, fucoidan, and alginate are extensively studied food and nonfood applications. Degree of sulfation and favorable physical properties are essentially required for tissue engineering applications. Therefore, our investigation explores the structural and gelling properties of novel polysaccharide porphyran (POR isolated from Porphyra vietnamensis by alkali hydrolysis. Percentage yield of POR was found to be 19.7%. The sulfate content of the polysaccharide was 11.1% and the main sugars present were D-galactose (16.1%, 3, 6-anhydro galactose (3, 6-AG (10.1% and 6-O-methyl D-galactose (7.81%. After hydrolysis D-galactose was again confirmed by paper chromatography (Rf: 0.8 and phenol-sulfuric acid method. Gelling properties, including gelling strength (241 g/cm 2 , gelling temperature (35.8°C, melting temperature (70.7 ± 0.4 and apparent viscosity (56.2 ? were also explored. Differential scanning calorimeter analysis showed purified fraction has gel melt between 70°C and 80°C and show glass transition between 35°C and 38°C. Viscometric analysis was examined to analyze the different behavior of SPs fraction under the influence of cationic and anionic salts and polysaccharides. Molecular mass of POR was determined (16,280. SPs were characterized by Fourier transform infrared and nuclear magnetic resonance spectroscopy, which showed the presence of linear backbone structure called as POR. The rheological behavior of POR exhibits a gel-like behavior close to the one observed in commercial agar.

  6. Relationship Between Composition, Structure and Permeability of Drilling Filter Cakes Relations entre la composition, la structure et la perméabilité des cakes de forage

    OpenAIRE

    Durand C.; Lecourtier J.; Rosenberg E.; Loeber L.

    2006-01-01

    During drilling operations there is a need to build mud cakes as impervious as possible on the wall of the borehole to prevent damage by fluid loss. To establish the relationship between the filtration properties of mud filter cakes and their structure, drilling fluids containing montmorillonite clay, flexible (Drispac) or rigid (xanthan) anionic polymers, electrolytes and barite were investigated. Standard API filtration and polymer adsorption measurements were performed. The cake structure ...

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

    Science.gov (United States)

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

    2014-04-21

    While phosphorescent cyclometalated iridium(iii) complexes have been widely studied, only correlations between oxidation potential EOX and Hammett constant ?, and between the redox gap (?EREDOX = EOX-ERED) and emission or absorption wavelength (?abs, ?em) have been reported. We present now a quantitative model based on Hammett parameters that rationalizes the effect of the substituents on the properties of cyclometalated iridium(iii) complexes. This simple model allows predicting the apparent redox potentials as well as the electrochemical gap of homoleptic complexes based on phenylpyridine ligands with good accuracy. In particular, the model accounts for the unequal effect of the substituents on both the HOMO and the LUMO energy levels. Consequently, the model is used to anticipate the emission maxima of the corresponding complexes with improved reliability. We demonstrate in a series of phenylpyridine emitters that electron-donating groups can effectively replace electron-withdrawing substituents on the orthometallated phenyl to induce a blue shift of the emission. This result is in contrast with the common approach that uses fluorine to blue shift the emission maximum. Finally, as a proof of concept, we used electron-donating substituents to design a new fluorine-free complex, referred to as EB343, matching the various properties, namely oxidation and reduction potentials, electrochemical gap and emission profile, of the standard sky-blue emitter FIrPic. PMID:24345847

  8. Structure-kinetic relationships of choriogonadotropin and related molecules.

    Science.gov (United States)

    Liu, L; Southers, J L; Cassels, J W; Banks, S M; Wehmann, R E; Blithe, D L; Chen, H C; Nisula, B C

    1989-06-01

    To assess how profound differences in carbohydrate and/or polypeptide structures affect parameters of plasma disappearance of glycoprotein hormones, we calculated and compared the initial volume of distribution, rate constants, and metabolic clearance rates of several highly purified human choriogonadotropin (hCG) analogues in monkeys. hCG, deglycosylated hCG, desialylated hCG, or core fragment of hCG-beta purified from pregnancy urine (beta-core) was administered as a rapid intravenous injection to adult male cynomolgus monkeys (n = 3/group). The metabolic clearance rates of deglycosylated hCG, beta-core fragment, and desialylated hCG were increased 15-, 47-, and 152-fold, respectively, over that of hCG. Their corresponding initial volumes of distribution, however, remained essentially unchanged compared with that of hCG and approximated the estimated plasma volume. In contrast, the fast and slow rate constants of plasma disappearance of the hCG analogues were increased as much as 18- and 23-fold, respectively, relative to those of hCG. These studies of structure-kinetic relationships in primates show that major carbohydrate and polypeptide modifications of a glycoprotein hormone cause profound changes in the rate constants of the disappearance curves without changes in the initial volume of distribution. PMID:2472071

  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. Structure–Function Relationships in Fungal Large-Subunit Catalases

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, A.; Valdez, V; Rudino-Pinera, E; Horjales, E; Hansberg, W

    2009-01-01

    Neurospora crassa has two large-subunit catalases, CAT-1 and CAT-3. CAT-1 is associated with non-growing cells and accumulates particularly in asexual spores; CAT-3 is associated with growing cells and is induced under different stress conditions. It is our interest to elucidate the structure-function relationships in large-subunit catalases. Here we have determined the CAT-3 crystal structure and compared it with the previously determined CAT-1 structure. Similar to CAT-1, CAT-3 hydrogen peroxide (H{sub 2}O{sub 2}) saturation kinetics exhibited two components, consistent with the existence of two active sites: one saturated in the millimolar range and the other in the molar range. In the CAT-1 structure, we found three interesting features related to its unusual kinetics: (a) a constriction in the channel that conveys H{sub 2}O{sub 2} to the active site; (b) a covalent bond between the tyrosine, which forms the fifth coordination bound to the iron of the heme, and a vicinal cysteine; (c) oxidation of the pyrrole ring III to form a cis-hydroxyl group in C5 and a cis-{gamma}-spirolactone in C6. The site of heme oxidation marks the starts of the central channel that communicates to the central cavity and the shortest way products can exit the active site. CAT-3 has a similar constriction in its major channel, which could function as a gating system regulated by the H{sub 2}O{sub 2} concentration before the gate. CAT-3 functional tyrosine is not covalently bonded, but has instead the electron relay mechanism described for the human catalase to divert electrons from it. Pyrrole ring III in CAT-3 is not oxidized as it is in other large-subunit catalases whose structure has been determined. Different in CAT-3 from these enzymes is an occupied central cavity. Results presented here indicate that CAT-3 and CAT-1 enzymes represent a functional group of catalases with distinctive structural characteristics that determine similar kinetics.

  11. 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

  12. Relationship between soil properties and natural regeneration pattern of Juniperus excelsa forest in Ziarat, Balochistan

    International Nuclear Information System (INIS)

    In this study relationship of soil properties with the natural regeneration pattern of Juniperus excelsa forests of Ziarat was evaluated. Thirty stands were quantitatively sampled from different areas of Ziarat, Balochistan. Out of 30 stands we observed sufficient recruitment of Juniper seedlings in 27 stands. Diverse regeneration pattern was observed among and within sampling locations. Zizri Tore Sagran occupied highest seedling numbers i.e. 439 plants ha/sup -1/ on north-east facing slope at 2948m altitude. Nishpa valley had 99 plants ha/sup -1/ on south west facing slope at 2660m altitude, which is lowest density. In this study we computed 194±103 plants ha/sup -1/ overall density and 67±21 cm/sup 2/ ha/sup -1/ average basal area. Mild relationship was observed between seedling numbers and stand density while stand basal area and seedling numbers exhibited positive significant correlation (r=0.281, p<.05). Soil characteristics showed significant differences among the variables at significant levels of (p<0.01) and (p<0.05). Generally, the vegetative characteristics of Juniperus excelsa in the study area had significant correlation with the soil characteristics. The combine data showed balanced size class structures of J-shaped distribution. (author)

  13. Relationship between physical properties of graphite and its texture

    International Nuclear Information System (INIS)

    The dependence of anisotropy of thermal conductivity and specific resistance of graphite obtained by means of piercing pressing on texture arising at different molding material flow rates is investigated. It is shown that anisotropy of physical properties is caused by the texture arising during the pressing process. With pressing rate growth the degree of the anisotropy increases in radial direction

  14. Using nonlinearity and spatiotemporal property modulation to control effective structural properties: dynamic rods

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Blekhman, Iliya I.

    2007-01-01

    What are the effective properties of a generally nonlinear material or structure, whose local properties are modulated in both space and time? It has been suggested to use spatiotemporal modulation of structural properties to create materials and structures with adjustable effective properties, and to call these dynamic materials or spatiotemporal composites. Also, according to theoretical predictions, structural nonlinearity enhances the possibilities of achieving specific effective properties....

  15. Artificial Microstructures to Investigate Microstructure-Property Relationships in Metallic Glasses

    Science.gov (United States)

    Sarac, Baran

    Technology has evolved rapidly within the last decade, and the demand for higher performance materials has risen exponentially. To meet this demand, novel materials with advanced microstructures have been developed and are currently in use. However, the already complex microstructure of technological relevant materials imposes a limit for currently used development strategies for materials with optimized properties. For this reason, a strategy to correlate microstructure features with properties is still lacking. Computer simulations are challenged due to the computing size required to analyze multi-scale characteristics of complex materials, which is orders of magnitude higher than today's state of the art. To address these challenges, we introduced a novel strategy to investigate microstructure-property relationships. We call this strategy "artificial microstructure approach", which allows us to individually and independently control microstructural features. By this approach, we defined a new way of analyzing complex microstructures, where microstructural second phase features were precisely varied over a wide range. The artificial microstructures were fabricated by the combination of lithography and thermoplastic forming (TPF), and subsequently characterized under different loading conditions. Because of the suitability and interesting properties of metallic glasses, we proposed to use this toolbox to investigate the different deformation modes in cellular structures and toughening mechanism in metallic glass (MG) composites. This study helped us understand how to combine the unique properties of metallic glasses such as high strength, elasticity, and thermoplastic processing ability with plasticity generated from heterostructures of metallic glasses. It has been widely accepted that metallic glass composites are very complex, and a broad range of contributions have been suggested to explain the toughening mechanism. This includes the shear modulus, morphology, size, spacing, volume fraction of the second phase, and strength and toughness of the interface. Previous studies suggest these contributions, however, do not provide quantitative experimental evidence. Within this thesis, we paid tribute to the complexity of the toughening mechanism by revealing the correlation between plastic zone size (Rp) and second phase spacing (s ), and the results guided us how to design elasticity through the second phase morphology (AB pore stacking) in MG heterostructures. The second phase elasticity and shear modulus were also found to be contributing to the overall elasticity. We identified the pores' ratio of diameter to spacing (d/s) as one of the major factors controlling the mechanical properties of MG hetero structures, which is most efficient when d/s ? 1. Effectiveness of MG heterostructures also depends on the size of the sample, w, in comparison to s. Our experimental findings illuminate the complexity in MG composites, which can be resolved with our artificial microstructure approach. Another subject where we use artificial microstructures is to identify the effect of length scales on structural properties of MG heterostructures. MG structures can be fabricated over 7 orders of magnitude length scale (nm to cm), where the effect of the feature size determines whether the deformation will be homogenous throughout the sample, it will be localized into shear bands, or it will not show any shear bands (no plasticity) during bending and tension. We investigated the deformation modes of Zr-based MGs in hexagonal cellular structures controlled by the relative density, and revealed three distinctive deformation regions: collective buckling, local failure, and global failure which originate from size effects in metallic glasses. The relative density of ˜25.0% was determined as the ideal relative density for energy absorption, strength and plasticity in MG cellular structures. Besides two specific examples studied in detail here, the artificial microstructure concept can be applied to a wide range of problems in micro

  16. 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.

  17. Thermal-structural relationship of individual titania nanotubes.

    Science.gov (United States)

    Brahmi, Hatem; Katwal, Giwan; Khodadadi, Mohammad; Chen, Shuo; Paulose, Maggie; Varghese, Oomman K; Mavrokefalos, Anastassios

    2015-12-01

    The thermal properties of nano-scale materials are largely influenced by their geometry. The zero, one and quasi one dimensional forms of the same material could exhibit unique thermal transport properties depending upon the shape and nano-scale feature size. In order to gain a clear understanding of the contributions from geometrical scattering effects on thermal transport, it is required to study these nano-materials in a single isolated form rather than in clusters or films. In the past decade, titanium dioxide nanotube arrays fabricated by anodic oxidation of titanium emerged as a useful semiconductor architecture for a variety of applications, particularly for solar energy conversion. Nonetheless, the thermal properties of individual nanotubes that are important for their use in high temperature applications have not been clearly understood. Here we report the thermal transport properties of individual titania nanotubes as revealed by our preliminary study using a suspended microdevice that facilitates the thermal conductivity measurements and crystal structure investigation on the same nanotube. The nanotubes were prepared by anodic oxidation of a titanium foil in HF-DMSO electrolyte at 60 V, having outer diameters in the range of 200 to 300 nm and wall thicknesses of ?30 to 70 nm in either amorphous or polycrystalline anatase phase. The thermal conductivity of single nanotubes was found to be very close to that of the amorphous phase (1.5 W mK(-1) and 0.85 W mK(-1) respectively) and it was only half of the thermal conductivity of the nanotube arrays in the film form. The thermal conductivity of bulk TiO2 is known to be almost six times higher. The observed thermal conductivity suppression in single nanotubes was explained using a transport model developed by considering diffuse phonon-surface scattering and scattering of phonons by ionized impurities of concentrations in the order of 10(18)-10(19) cm(-3). PMID:26512924

  18. Thermal-structural relationship of individual titania nanotubes

    Science.gov (United States)

    Brahmi, Hatem; Katwal, Giwan; Khodadadi, Mohammad; Chen, Shuo; Paulose, Maggie; Varghese, Oomman K.; Mavrokefalos, Anastassios

    2015-11-01

    The thermal properties of nano-scale materials are largely influenced by their geometry. The zero, one and quasi one dimensional forms of the same material could exhibit unique thermal transport properties depending upon the shape and nano-scale feature size. In order to gain a clear understanding of the contributions from geometrical scattering effects on thermal transport, it is required to study these nano-materials in a single isolated form rather than in clusters or films. In the past decade, titanium dioxide nanotube arrays fabricated by anodic oxidation of titanium emerged as a useful semiconductor architecture for a variety of applications, particularly for solar energy conversion. Nonetheless, the thermal properties of individual nanotubes that are important for their use in high temperature applications have not been clearly understood. Here we report the thermal transport properties of individual titania nanotubes as revealed by our preliminary study using a suspended microdevice that facilitates the thermal conductivity measurements and crystal structure investigation on the same nanotube. The nanotubes were prepared by anodic oxidation of a titanium foil in HF-DMSO electrolyte at 60 V, having outer diameters in the range of 200 to 300 nm and wall thicknesses of ~30 to 70 nm in either amorphous or polycrystalline anatase phase. The thermal conductivity of single nanotubes was found to be very close to that of the amorphous phase (1.5 W mK-1 and 0.85 W mK-1 respectively) and it was only half of the thermal conductivity of the nanotube arrays in the film form. The thermal conductivity of bulk TiO2 is known to be almost six times higher. The observed thermal conductivity suppression in single nanotubes was explained using a transport model developed by considering diffuse phonon-surface scattering and scattering of phonons by ionized impurities of concentrations in the order of 1018-1019 cm-3.

  19. A new measure of population structure using multiple single nucleotide polymorphisms and its relationship with FST

    Directory of Open Access Journals (Sweden)

    Sarkar Bayazid

    2009-02-01

    Full Text Available Abstract Background Large-scale genome-wide association studies are promising for unraveling the genetic basis of complex diseases. Population structure is a potential problem, the effects of which on genetic association studies are controversial. The first step to systematically quantify the effects of population structure is to choose an appropriate measure of population structure for human data. The commonly used measure is Wright's FST. For a set of subpopulations it is generally assumed to be one value of FST. However, the estimates could be different for distinct loci. Since population structure is a concept at the population level, a measure of population structure that utilized the information across loci would be desirable. Findings In this study we propose an adjusted C parameter according to the sample size from each sub-population. The new measure C is based on the c parameter proposed for SNP data, which was assumed to be subpopulation-specific and common for all loci. In this study, we performed extensive simulations of samples with varying levels of population structure to investigate the properties and relationships of both measures. It is found that the two measures generally agree well. Conclusion The new measure simultaneously uses the marker information across the genome. It has the advantage of easy interpretation as one measure of population structure and yet can also assess population differentiation.

  20. Mechanical properties and the structure of magnetic composite materials

    Directory of Open Access Journals (Sweden)

    L.A. Dobrza?ski

    2006-08-01

    Full Text Available Purpose: The purpose of the paper is to present the material and technological solution which makes possibleobtaining soft and hard magnetic composite materials: nanocrystalline material – polymer.Design/methodology/approach: The main base of the paper is to compare the structure and mechanicalproperties of chosen magnetic composite materials with polymer matrix reinforced with Nd-Fe-B or FINEMETparticles manufactured by one-sided uniaxal pressing. The complex relationships among the manufacturingtechnology of these materials, their microstructure, as well as their mechanical and physical properties wereevaluated.Findings: Modern magnetic materials have optimum technology of production with properties that allow forminiaturizing, simplification and lowering the costs of devicesPractical implications: The manufacturing of composite materials greatly expands the applicable possibilitiesof nanocrystalline powders of magnetically hard and soft materials however further examination obtainimproved properties of magnetic composite materials. The investigations of constructing of new machines anddevices with these materials elements are still needed.Originality/value: The paper shows the base of the material and technological solution which make possibleobtaining magnetic composite materials and their mechanical properties which are not commonly presented inother papers.

  1. Calculating Internal Structure and Mass-Radius Relationships of Rocky Exoplanets

    Science.gov (United States)

    Desch, Steve; Lorenzo, Alejandro; Ko, Byeongkwan

    2015-12-01

    We present a code (ExoPlex) we have written to calculate the internal structures and mass-radius relationships of rocky exoplanets. Existing codes described in the literature consider only a limited range of compositions for the core and mantle, and they generally assume that mineral phases are always present as a single high-pressure polymorph. These restrictions arise from the need to specify material properties, such as bulk modulus, at every depth in the planet, which requires knowledge of the phases present. Existing codes also neglect the effects of temperature on material properties, assuming values attained in the low-temperature limit. Our code circumvents these problems. We specify a stoichiometry for the core and for the mantle, we find the pressure at depth by integrating the equation of hydrostatic equilibrium, and we assume adiabatic temperature gradients in the mantle and in the core. We then supply pressure, temperature, and composition as inputs to the PerpleX software package that calculates the mineral phases present in thermodynamic equilibrium, and their material properties. This allows us to explore mass-radius relationships across a wide range of compositional and mineralogical parameter space. We discuss preliminary results.

  2. Scientific habits of mind: A reform of structure and relationships

    Science.gov (United States)

    Mooney, Linda Beth

    This research was designed to broaden current elementary science reform efforts by including the voices of our young scientists. Ten high school students who were defined as possessing both coherent science knowledge and scientific habits of mind were selected for the study. Through a three-part series of in-depth, phenomenological interviews, these students revealed early childhood experiences from birth through age ten to which they attributed their development of science knowledge and scientific habits of mind. Educational connoisseurship and criticism provided the framework through which the experiences were analyzed. The research revealed the overwhelming role of scientific habits of mind in the current success of these young scientists. Scientific habits of mind were developed through the structures and relationships in the home. Parents of the participants provided a non-authoritarian, fun, playful, tolerant atmosphere in which messes and experimentation were the norm. Large blocks of uninterrupted, unstructured time and space that "belonged" to the child allowed these children to follow where curiosity led. Frequently, the parent modeled scientific habits of mind. Good discipline in the minds of these families had nothing to do with punishments, rewards, or rules. The parents gave the children responsibilities, "free rein," and their trust, and the children blossomed in that trust and mutual respect. Parents recognized and supported the uniqueness, autonomy, interests, and emotions of the child. Above all, the young scientists valued the time, freedom, patience, and emotional support provided by their parents. For girls, construction toys, hot wheels, sand boxes, and outdoor experiences were particularly important. Art classes, free access to art media, sewing, music, and physical activity facilitated observational skills and spatial relationship development. The girls knew that doing traditionally masculine and feminine activities were acceptable and celebrated by both parents. The time has come to include scientific habits of mind in science education reform. The time has come for science education reform to espouse fun and playfulness, large blocks of unstructured time, responsibility and trust, emotional support, and caring teacher-child relationships. The time has come to listen to the voices of our young scientists.

  3. 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

  4. 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.

  5. Relationship of geological and geothermal field properties; mid-continent area, USA, an example

    Energy Technology Data Exchange (ETDEWEB)

    Forster, A. (GeoforschungsZentrum, Potsdam (Germany)); Merriam, D.F. (Kansas Geological Survey, Lawrence, KS (United States)); Brower, J.C. (Syracuse Univ., NY (United States))

    1993-02-01

    Quantitative approaches to data analysis have become important in basin modeling and mineral-resource estimation in the last decade. The interrelation of geological, geophysical, geochemical, and geohydrological variables is important in adjusting a model to a real-world situation. Revealing the interdependences of variables can contribute in understanding the processes interacting in sedimentary basins. It is simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques can be used to ascertain the relations of standardized spatial data. In this example, structural configuration on five different stratigraphic horizons, one total sediment thickness map, and four maps of geothermal information were compared. The structural maps were highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients (1) derived from borehole logging measurements under equilibrium conditions with the surrounding rock and (2) derived from unequilibrated bottomhole temperatures (BHT) are mainly independent of each other. This was expected and confirmed for the two temperature maps at 1000 ft which were constructed using both types of gradient values. Thus, it is evident that the use of BHT without correction to equilibrium conditions does not reflect the geothermal regime of the area. Nevertheless, it seemed useful to determine to what degree unequilibrated temperatures could reflect relationships to the geological conditions. Comparing all maps of geothermal information versus the structural and the sediment thickness maps it was determined that all correlations are moderately negative or slightly positive. These results are clearly shown by the cluster analysis and the principal components and support the assumption that the temperatures within the sediment are related closely to the lithological properties (rock conductivity) of the stratigraphic units.

  6. Establishing collaborative structures and relationships: Teacher leaders' experiences

    Science.gov (United States)

    Canizo, Thea Lynne

    2002-04-01

    The purpose of this study was to explore teacher leaders' experiences as they attempted to establish collaborative structures and relationships resulting in improved science instruction at their schools. Teacher leaders were middle school science facilitators, full-time classroom teachers who acted as liaisons between the science teachers at their schools and a change initiative funded by the National Science Foundation. This was a qualitative study, using interviews to create a case study. The researcher used a three-part interview design developed by Seidman (1991). Six research questions served as a framework for the data analysis. Participants identified the following as factors which contributed to their success: support from the principal, other science teachers, central staff personnel, and the district-wide group of science facilitators; professional development; and the successful completion of a scope and sequence for science instruction. Factors identified as hindering their success were: lack of support or conflict with the principal; resistance to change; time constraints; a district policy which limited meeting time; teacher and administrator turnover; tension between the middle school and junior high school models; and personal doubts. From descriptions of their understanding and exercising of leadership, the researcher concluded that teacher leaders had become empowered. The school culture was seen to have a great effect on teacher leaders. The contrasts between a school with a positive culture and another school in disarray were presented. Structures such as summer institutes and release time during the school day were identified as critical for giving teachers the time needed to establish more collaborative working relationships. Once greater trust and understanding were present, teachers were better able to examine their teaching practices more critically. Participants identified mentoring of new members, a continuing role for science facilitators, and central support as necessary for ensuring the sustainability of the changes made during the years of the grant initiative. The researcher concluded that teacher leaders can be a powerful force for bringing about change in schools when provided with training and time during the school day to work with colleagues.

  7. Relationships between microstructure and mechanical properties in ductile cast irons: a review

    International Nuclear Information System (INIS)

    The progress achieved in the understanding of the relationships between the microstructure and the mechanical properties of ductile cast iron is reviewed. It is also described the applications of heat treatment of austempered to ductile irons (ADI), which have allowed to improve substantially the mechanical properties of these materials. It is proposed a research program to obtain the crack growth resistance under corrosive atmospheres and to model the mechanical properties. (Author) 83 refs

  8. 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.

  9. 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

  10. Relationships Between Skin Properties and Body Water Level

    OpenAIRE

    Andersson, Ida; Hedvall, Anders

    2013-01-01

    A need for a quantitative method to determine body water level has been identified by a team of Clinical Innovation Fellows at the Centre for Technology in Medicine and Health (CTMH). A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing. A possible solution is a sensor that would measure alterations in skin properties due to changes in total body water. CTMH has had an idea of such a senso...

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

    OpenAIRE

    C.H. Azhari; Wong, S. F.

    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...

  12. Relationships between fracture toughness and other material properties. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Perra, M.; Finnie, I.

    1974-01-01

    The key experimental and analytical studies which have led to our present understanding of the mechanisms of ductile fracture are reviewed. It is concluded that insufficient progress has been made in the quantitative description of ductile separation mechanisms on a microscale to allow the realistic prediction of fracture toughness from material properties and microstructure. An experimental study of ductile fracture is underway which has the aim of determining the growth rate of voids in known plastic deformation fields as a function of triaxiality of stress and material work-hardening. Novel specimens of particularly well characterized microstructure are utilized.

  13. Synthesis, structure and properties of polymer nanocomposites

    Science.gov (United States)

    Zeng, Changchun

    Over the last decade, the concept of utilizing nanoparticles to enhance polymer performance has drawn a great deal of research interest. Significant property enhancement can be achieved with a small amount of addition of nanoparticles. Spherical, platelet or tube/fiber like particles have all been used in the fabrication of nanocomposites. In this study, we chose platelet like clay particles to study the particle dispersion and properties of polymer nanocomposites and polymer nanocomposite foams. Free radical polymerization of methylmethacrylate (MMA) and styrene (St) in the presence of clay nanoparticles were studied in detail. The effect of interactions between the monomer, the initiator and clay surface modification was studied. By careful surface modification of clay surface and choice of initiator, clay particles can be dispersed uniformly at the nanometer scale (exfoliation). Exfoliation was achieved for PS nanocomposites with a clay concentration as high as 20 wt%. For PMMA, although fully exfoliated nanocomposite was only observed for clay concentration of 5 wt%, substantial exfoliation was observed in the 20 wt% nanocomposite. Nanocomposites were also prepared by extrusion compounding, with or without the aid of CO2. The effect of processing conditions on the degree of clay dispersion was studied. The relationships between clay dispersion, surfactant thermal stability and the resulting thermal properties, e.g., thermal stability, dimension stability, fire resistance were investigated. Novel polymer clay nanocomposite foams were prepared using carbon dioxide as the foaming agent. The role of clay on the foaming process was thoroughly investigated. It was found that clay serves as an efficient nucleation agent. Nucleation efficiency increases as the degree of clay dispersion improves. The exfoliated clay provides the highest nucleation efficiency. Nucleation efficiency can be further improved by tuning the interaction between polymer, CO2 and the surface property of clay nanoparticles. Ultramicrocellular PMMA nanocomposite foam was successfully prepared. Moreover, based on the understanding of clay dispersion and polymer-CO2-clay surface interaction, a new approach to produce microcellular PS nanocomposite foams was demonstrated, which has considerable potential of expanding the commercial applications of microcellular foaming technology.

  14. Structure and properties of glassy metals

    International Nuclear Information System (INIS)

    Glassy metals may be obtained in a number of ways, electrochemical deposition, vacuum evaporation, sputtering, liquid quenching. The basic principles of the preparation techniques, the type of glassy alloy best obtained and the most important limitations of each technique are given. A number of experimental methods for examining the structure of glassy metals are available, the analysis of x-ray diffraction patterns being the most significant one used to date. Much experimental work has been concerned with many aspects of the amorphous-to-crystalline transition, however, this is still little understood. The glassy metals have some unique physical properties. They have generally high resistivity, > 100?omega cm at room temperature and very low temperature coefficients which can be zero or negative. The glassy metals have provided new opportunities for studying composition effects on the Kondo effect. Superconductivity has been reported in both vacuum deposited and liquid quenched samples. The magnetic properties of a number of ferromagnetic glassy alloys have been studied. Difficulties in specimen preparation held up investigations of mechanical properties and there is much difficulty in explaining the usual ductility of these glasses. 133 refs

  15. Classification Framework and Structure-Activity-Relationship (SAR) of Tetracycline-Structure-Based Drugs

    OpenAIRE

    Domenico Fuoco

    2011-01-01

    By studying the literature about tetracyclines (TCs), it becomes clearly evident that TCs are very dynamic molecules. In some cases, their structure-activity-relationship (SAR) are well known, especially against bacteria, while against other targets, they are virtually unknown. In other diverse fields of research—such as neurology, oncology and virology—the utility and activity of the tetracyclines are being discovered and are also emerging as new technological fronts. The first aim of this p...

  16. Structural Properties of III-Nitride Semiconductors

    Science.gov (United States)

    Wei, Yong

    Group III-nitride semiconductors have been commercially used in the fabrication of light-emitting diodes and laser diodes, covering the ultraviolet-visible-infrared spectral range and exhibit unique properties suitable for modern optoelectronic applications. InGaN ternary alloys have energy band gaps ranging from 0.7 to 3.4 eV. It has a great potential in the application for high efficient solar cells. AlGaN ternary alloys have energy band gaps ranging from 3.4 to 6.2 eV. These alloys have a great potential in the application of deep ultra violet laser diodes. However, there are still many issues with these materials that remain to be solved. In this dissertation, several issues concerning structural, electronic, and optical properties of III-nitrides have been investigated using transmission electron microscopy. First, the microstructure of InxGa1-xN (x = 0.22, 0.46, 0.60, and 0.67) films grown by metal-modulated epitaxy on GaN buffer /sapphire substrates is studied. The effect of indium composition on the structure of InGaN films and strain relaxation is carefully analyzed. High luminescence intensity, low defect density, and uniform full misfit strain relaxation are observed for x = 0.67. Second, the properties of high-indium-content InGaN thin films using a new molecular beam epitaxy method have been studied for applications in solar cell technologies. This method uses a high quality AlN buffer with large lattice mismatch that results in a critical thickness below one lattice parameter. Finally, the effect of different substrates and number of gallium sources on the microstructure of AlGaN-based deep ultraviolet laser has been studied. It is found that defects in epitaxial layer are greatly reduced when the structure is deposited on a single crystal AlN substrate. Two gallium sources in the growth of multiple quantum wells active region are found to cause a significant improvement in the quality of quantum well structures.

  17. 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.

  18. 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.

  19. Review of Quantitative Structure - Activity Relationships for Acute Mammalian Toxicity

    Directory of Open Access Journals (Sweden)

    Iglika Lessigiarska

    2006-12-01

    Full Text Available This paper reviews Quantitative Structure-Activity Relationship (QSAR models for acute mammalian toxicity published in the last decade. A number of QSAR models based on cytotoxicity data from mammalian cell lines are also included because of their possible use as a surrogate system for predicting acute toxicity to mammals. On the basis of the review, the following conclusions can be made: i a relatively small number of models for in vivo toxicity are published in the literature. This is due to the nature of the endpoint - acute systemic toxicity is usually related to whole body phenomena and therefore is very complex. The complexity of the mechanisms involved leads to difficulties in the QSAR modelling; ii most QSAR models identify hydrophobicity as a parameter of high importance for the modelled toxicity. In addition, many models indicate the role of the electronic and steric effects; iii most of the literature-based models are restricted to single chemical classes. Models based on more heterogeneous data sets are those incorporated in expert systems. In general, the QSAR models for mammalian toxicity identified in this review are considered useful for investigating the mechanisms of toxicity of defined chemical classes. However, for predictive purposes in the regulatory assessment of chemicals most of the models require additional information to satisfy internationally agreed validation principles. In addition, the development of new models covering larger chemical domains would be useful for the regulatory assessment of chemicals.

  20. Nicotinamide Phosphoribosyltransferase Inhibitors, Design, Preparation, and Structure-Activity Relationship

    DEFF Research Database (Denmark)

    Christensen, Mette K; Erichsen, Kamille D

    2013-01-01

    Existing pharmacological inhibitors for nicotinamide phosphoribosyltransferase (NAMPT) are promising therapeutics for treating cancer. By using medicinal and computational chemistry methods, the structure-activity relationship for novel classes of NAMPT inhibitors is described, and the compounds are optimized. Compounds are designed inspired by the NAMPT inhibitor APO866 and cyanoguanidine inhibitor scaffolds. In comparison with recently published derivatives, the new analogues exhibit an equally potent antiproliferative activity in vitro and comparable activity in vivo. The best performing compounds from these series showed subnanomolar antiproliferative activity toward a series of cancer cell lines (compound 15: IC50 0.025 and 0.33 nM, in A2780 (ovarian carcinoma) and MCF-7 (breast), respectively) and potent antitumor in vivo activity in well-tolerated doses in a xenograft model. In an A2780 xenograft mouse model with large tumors (500 mm(3)), compound 15 reduced the tumor volume to one-fifth of the starting volume at a dose of 3 mg/kg administered ip, bid, days 1-9. Thus, compounds found in this study compared favorably with compounds already in the clinic and warrant further investigation as promising lead molecules for the inhibition of NAMPT.

  1. 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.

  2. 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.

  3. Structure-property evolution during polymer crystallization

    Science.gov (United States)

    Arora, Deepak

    The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical spectroscopy, is not caused by packing/jamming of spherulites but by the formation of a percolating network structure. The effect of strain, Weissenberg number (We ) and specific mechanical work (w) on rate of crystallization (nucleation followed by growth) and on growth of anisotropy was studied for shear-induced crystallization of isotactic poly-1-butene. The samples were sheared for a finite strain at the beginning of the experiment and then crystallized without further flow (Janeschitz-Kriegl protocol). Strain requirements to attain steady state/leveling off of the rate of crystallization were found to be much larger than the strain needed to achieve steady state of flow. The large strain and We>1 criteria were also observed for morphological transition from spherulitic growth to oriented growth. An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of 20 ms. The experiments were controlled and analyzed with a LabVIEW(TM) based code (LabVIEW(TM) 7.1) in real time. The SALS apparatus was custom built for ExxonMobil Research in Clinton NJ.

  4. 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.

  5. Study of quantitative structure - property methods of linear regression analysis and neural networks

    Directory of Open Access Journals (Sweden)

    ?.?. ??????

    2007-02-01

    Full Text Available  Modelation of protonisation dependence on the values of molecular discriptors of various classesorganic compounds is carried out by the methods of multydimensional regressive analysis and neuron nets. Advantage of neuron nets method for guantitive relationships structure-property description is shown.

  6. Looking beyond Lewis Structures: A General Chemistry Molecular Modeling Experiment Focusing on Physical Properties and Geometry

    Science.gov (United States)

    Linenberger, Kimberly J.; Cole, Renee S.; Sarkar, Somnath

    2011-01-01

    We present a guided-inquiry experiment using Spartan Student Version, ready to be adapted and implemented into a general chemistry laboratory course. The experiment provides students an experience with Spartan Molecular Modeling software while discovering the relationships between the structure and properties of molecules. Topics discussed within…

  7. 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

  8. 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.

  9. Mechanical properties and structure of austempered ductile iron -ADI

    Directory of Open Access Journals (Sweden)

    Krzy?ska A.

    2007-01-01

    Full Text Available The results of experimental study of austempered ductile iron are presented. The aim of the investigations was to look closer into the structure – mechanical properties relationships of this very attractive cast material. The experiment was carried out with 500 7 grade ductile iron, which was austempered using different parameters of heat treatment. The specimens were first solution treated 1 hour in 910oC and then isothermally quenched for different time in silicon oil bath of temperature 275, 325, 300 and 350oC. The mechanical properties heat treated specimens were tested in tensile to evaluate yield stress Re, 0.2, tensile strength Rm and elongation A10. Additionally hardness of heat treated samples was measured using Brinell-Rockwell hardness tester. Structure of the specimens was studied either with conventional metallography, scanning (SEM and transmission (TEM electron microscopy. It followed from the study that conventional grade ductile iron enabled to produce both low and high strength ADI, depend on heat treatment parameters. As expected the low temperature isothermal quenching produced higher strength ADI compare to the same ductile iron but austempered at 350oC. It was discovered however, that low yield strength ADI obtained for short time quenching at 275oC exhibited high strengthening effect while strained in tensile. So it was concluded that this had to by cause by large amount of untransformed austenite, which FCC lattice is characterized by high strengthening coefficient.

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

    International Nuclear Information System (INIS)

    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.

  11. Processing microstructure property relationships in severely deformed tantalum

    International Nuclear Information System (INIS)

    Bars of as-cast, large grained and highly textured Ta were deformed by multipass equal channel angular extrusion (ECAE) at room temperature to strains of 4.6 through 90 deg. die-angle tooling. The ability of ECAE processing to produce a uniform fine-grained microstructure with homogenous deformation characteristics is investigated. Comparisons of the microstructure and mechanical properties after four consecutive extrusions via route C (180 deg. rotation between passes) and E (2C, 90 deg. rotation then 2C) are made in both the as-worked (submicron-scale grains) and recrystallized (micron-scale grains) states. It is shown that the as-worked grain size levels out at 200-300 nm after four passes. The recrystallized grain size after two to four passes is ?10-15 ?m with microstructural uniformity that is dependent on the microstructural uniformity in the starting material. It is also demonstrated that four pass ECAE processing of as-cast large grained BCC materials is not necessarily enough to homogenize texture. A pre-processing step with combined severe plastic deformation and recrystallization improves microstructural uniformity and lessens texture gradients in subsequent deformation processing steps

  12. Global Relationships Among the Physical Properties of Stellar Systems

    CERN Document Server

    Burstein, D; Faber, S; Nolthenius, R; Burstein, David; Bender, Ralf; Faber, Sandra; Nolthenius, Richard

    1997-01-01

    The kappa-space three-dimensional parameter system was originally defined for the physical properties of dynamically hot galaxies. Here we define self-consistent kappa-parameters for disk galaxies, galaxy groups and clusters, and globular clusters and project an integrated view of the major classes of self-gravitating, equilibrium stellar systems in the universe. Six different fundamental planes exist that are interrelated and interconnected - the ``cosmic metaplane.'' The kappa-3 vs. kappa-1 projection (M/L vs. Mass) views all planes edge-on, M/L increasing or constant with Mass. Within the cosmic metaplane (kappa-2 vs. kappa-1 projection), no stellar system violates the rule that kappa-1 + kappa-2 < 8, meaning the maximum volume luminosity density of stellar systems varies as a (K times M^{-4/3}; the ``zone of exclusion''). Galaxies march away from ZOE as a function of Hubble type: DHGs closest, Sm-Irr's furthest away. We test current ideas of galaxy formation via hierarchical clustering and merging and ...

  13. 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

  14. Clarifying Media Dependency Relationships through Structural Equation and Measurement Models.

    Science.gov (United States)

    McDonald, Daniel G.

    A study was conducted to clarify some of the ambiguous findings reported in the media dependency literature. Specifically, it sought to establish whether relationships between use of the media and surveillance gratifications obtained from that use were affected by an individual's medium of primary reliance or whether these relationships might be…

  15. Multidimensional Aspects of Marital Relationships: Factor Structure of the MSI.

    Science.gov (United States)

    Wendler, Cathy L. W.; Zachary, Robert A.

    Because marriage and family counselors need to examine all areas of a marital relationship, a study was undertaken to investigate several parts of a marital relationship using the Marital Satisfaction Inventory (MSI). Participants (N=495) who were engaged in conjoint marital counseling, completed the MSI, a self-reporting measure with 280…

  16. Plant trait-species abundance relationships vary with environmental properties in subtropical forests in eastern china.

    Science.gov (United States)

    Yan, En-Rong; Yang, Xiao-Dong; Chang, Scott X; Wang, Xi-Hua

    2013-01-01

    Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivariate (PCA axes) environmental properties such as air humidity, soil moisture content, soil temperature, soil pH, and soil organic matter, nitrogen (N) and phosphorus (P) contents. At the landscape scale, plant maximum height, and twig and stem wood densities were positively correlated, whereas mean leaf area (MLA), leaf N concentration (LN), and total leaf area per twig size (TLA) were negatively correlated with species abundance. At the plot scale, plant maximum height, leaf and twig dry matter contents, twig and stem wood densities were positively correlated, but MLA, specific leaf area, LN, leaf P concentration and TLA were negatively correlated with species abundance. Plant trait-species abundance relationships shifted over the range of seven single environmental properties and along multivariate environmental axes in a similar way. In conclusion, strong relationships between plant traits and species abundance existed among and within communities. Significant shifts in plant trait-species abundance relationships in a range of environmental properties suggest strong environmental filtering processes that influence species abundance and rarity in the studied subtropical forests. PMID:23560114

  17. A structure-activity relationship study of platelet-activating factor

    Energy Technology Data Exchange (ETDEWEB)

    Surles, J.R.

    1987-01-01

    Several analogues of platelet-activating factor (1-0-alkyl-2-0-acetyl-sn-glycero-3-phosphocholine, PAF), an alkylglycerophospholipid that was found to be a mediator in Type I immediate hypersensitivity and also possessed potent hypotensive properties, were synthesized. These PAF analogues were evaluated in a qualitative structure-activity relationship study for their rabbit neutrophil degranulation properties and their antihypertensive properties in rats. Variations were made in each of the moieties attached to the three glycerol backbone carbons. Variation in sn-1-0-alkyl chain length from fourteen to nineteen carbons and introduction of one or two double bonds revealed that the 1-0-hexadecyl species of PAF was the most active analogue in this series in our assay systems. Substitution of various deoxyalkyl groups for the 2-0-acetyl moiety resulted in severely diminished bioactivities and no inhibition of rat plasma acetylhydrolase activity. Substitution of bulky trialkylammonium moieties for the trimethylammonium portion of the phosphocholine moiety resulted in an analogue (triethylammonium, 41) with reduced immediate hypersensitivity properties and 560% relative antihypertensive potency.

  18. Structure-activity relationships for novel drug precursor N-substituted-6-acylbenzothiazolon derivatives: A theoretical approach

    Science.gov (United States)

    S?d?r, Yadigar Gülseven; S?d?r, ?sa

    2013-08-01

    In this study, the twelve new modeled N-substituted-6-acylbenzothiazolon derivatives having analgesic analog structure have been investigated by quantum chemical methods using a lot of electronic parameters and structure-activity properties; such as molecular polarizability (?), dipole moment (?), EHOMO, ELUMO, q-, qH+, molecular volume (Vm), ionization potential (IP), electron affinity (EA), electronegativity (?), molecular hardness (?), molecular softness (S), electrophilic index (?), heat of formation (HOF), molar refractivity (MR), octanol-water partition coefficient (log P), thermochemical properties (entropy (S), capacity of heat (Cv)); as to investigate activity relationships with molecular structure. The correlations of log P with Vm, MR, ?, EA, EHOMO - ELUMO (?E), HOF in aqueous phase, ?, ?, S, ? parameters, respectively are obtained, while the linear relation of log P with IP, Cv, HOF in gas phase are not observed. The log P parameter is obtained to be depending on different properties of compounds due to their complexity.

  19. 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...

  20. Development of structure-activity relationship for metal oxide nanoparticles

    Science.gov (United States)

    Liu, Rong; Zhang, Hai Yuan; Ji, Zhao Xia; Rallo, Robert; Xia, Tian; Chang, Chong Hyun; Nel, Andre; Cohen, Yoram

    2013-05-01

    Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions.Nanomaterial structure-activity relationships (nano-SARs) for metal oxide nanoparticles (NPs) toxicity were investigated using metrics based on dose-response analysis and consensus self-organizing map clustering. The NP cellular toxicity dataset included toxicity profiles consisting of seven different assays for human bronchial epithelial (BEAS-2B) and murine myeloid (RAW 264.7) cells, over a concentration range of 0.39-100 mg L-1 and exposure time up to 24 h, for twenty-four different metal oxide NPs. Various nano-SAR building models were evaluated, based on an initial pool of thirty NP descriptors. The conduction band energy and ionic index (often correlated with the hydration enthalpy) were identified as suitable NP descriptors that are consistent with suggested toxicity mechanisms for metal oxide NPs and metal ions. The best performing nano-SAR with the above two descriptors, built with support vector machine (SVM) model and of validated robustness, had a balanced classification accuracy of ~94%. An applicability domain for the present data was established with a reasonable confidence level of 80%. Given the potential role of nano-SARs in decision making, regarding the environmental impact of NPs, the class probabilities provided by the SVM nano-SAR enabled the construction of decision boundaries with respect to toxicity classification under different acceptance levels of false negative relative to false positive predictions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01533e

  1. Quantitative analysis of structure-activity relationships of tetrahydro-2H-isoindole cyclooxygenase-2 inhibitors.

    Science.gov (United States)

    Khayrullina, V R; Gerchikov, A Ya; Lagunin, A A; Zarudii, F S

    2015-01-01

    Using the GUSAR program, structure-activity relationships on inhibition of cyclooxygenase-2 (COX-2) catalytic activity were quantitatively analyzed for twenty-six derivatives of 4,5,6,7-tetrahydro-2H-isoindole, 2,3-dihydro-1H-pyrrolyzine, and benzothiophene in the concentration range of 0.6-700 nmol/liter IC50 values. Six statistically significant consensus QSAR models for prediction of IC50 values were designed based on MNA- and QNA-descriptors and their combinations. These models demonstrated high accuracy in the prediction of IC50 values for structures of both training and test sets. Structural fragments of the COX-2 inhibitors capable of strengthening or weakening the desired property were determined using the same program. This information can be taken into consideration on molecular design of new COX-2 inhibitors. It was shown that in most cases, the influence of structural fragments on the inhibitory activity of the studied compounds revealed with the GUSAR program coincided with the results of expert evaluation of their effects based on known experimental data, and this can be used for optimization of structures to change the value of their biological activity. PMID:25754042

  2. Structure Property Studies for Additively Manufactured Parts

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-17

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

  3. 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.

  4. Relationship between hydraulic properties and plant coverage of the closed-landfill soils in Piacenza (Po Valley, Italy)

    Science.gov (United States)

    Cassinari, C.; Manfredi, P.; Giupponi, L.; Trevisan, M.; Piccini, C.

    2015-07-01

    In this paper the results of a study of soil hydraulic properties and plant coverage of a landfill located in Piacenza (Po Valley, Italy) are presented, together with the attempt to relate the hydraulic properties in relation with plant coverage. The measured soil water retention curve was first compared with the output of pedotransfer functions taken from the literature and then compared with the output of the same pedotransfer functions applied to a reference soil. The landfill plant coverage was also studied. The relationship between soil hydraulic properties and plant coverage showed that the landfill soils have a low water content available for plants. The soils' low water content, together with a lack of depth and a compacted structure, justifies the presence of a nitrophilous, disturbed-soil vegetation type, dominated by ephemeral annual species (therophytes).

  5. Analysis of genetic structure and relationship among nine indigenous Chinese chicken populations by the Structure program

    Indian Academy of Sciences (India)

    H. F. Li; W. Han; Y. F. Zhu; J. T. Shu; X. Y. Zhang; K. W. Chen

    2009-08-01

    The multi-locus model-based clustering method Structure program was used to infer the genetic structure of nine indigenous Chinese chicken (Gallus gallus) populations based on 16 microsatellite markers. Twenty runs were carried out at each chosen value of predefined cluster numbers $(K)$ under admixture model. The Structure program properly inferred the presence of genetic structure with 0.999 probabilities. The genetic structure not only indicated that the nine kinds of chicken populations were defined actually by their locations, phenotypes or culture, but also reflected the underlying genetic variations. At $K = 2$, nine chicken populations were divided into two main clusters, one light-body type, including Chahua chicken (CHA), Tibet chicken (TIB), Xianju chicken (XIA), Gushi chicken (GUS) and Baier chicken (BAI); and the other heavy-body type, including Beijing You chicken (YOU), Xiaoshan chicken (XIA), Luyuan chicken (LUY) and Dagu chicken (DAG). GUS and DAG were divided into independent clusters respectively when equaled 4, 5, or 6. XIA and BIA chicken, XIA and LUY chicken, TIB and CHA chicken still clustered together when equaled 6, 7, and 8, respectively. These clustering results were consistent with the breeding directions of the nine chicken populations. The Structure program also identified migrants or admixed individuals. The admixed individuals were distributed in all the nine chicken populations, while migrants were only distributed in TIB, XIA and LUY populations. These results indicated that the clustering analysis using the Structure program might provide an accurate representation of the genetic relationship among the breeds.

  6. Family Structure History: Links to Relationship Formation Behaviors in Young Adulthood

    Science.gov (United States)

    Ryan, Suzanne; Franzetta, Kerry; Schelar, Erin; Manlove, Jennifer

    2009-01-01

    Using data from three waves of the National Longitudinal Study of Adolescent Health (N = 4,667), we examined the intergenerational link between parental family structure history and relationship formation in young adulthood. We investigated (a) whether parental family structure history is associated with young adults' own relationship formation…

  7. [Structure and properties of proprotein convertase inhibitors].

    Science.gov (United States)

    Kibirev, V K; Osadchuk, T V

    2012-01-01

    This review is devoted to structure and properties of proprotein convertases (PCs), the intracellular Ca(2+)-dependent serine endoproteases of mammalia, that play the essential role in the processing of inactive protein precursors and their transforming into bioactive mature products. PCs are also implicated in development of a great variety of diseases including bacterial or viral infections and such pathologies as cancer, Alzheimer's disease, obesity and so on. Owing to these findings, PCs are considered as promising targets for design of their inhibitors and development of new potential therapeutic agents. Only several endogenous protein inhibitors are identified now for PCs: pro7B2 (Proprotein 7B2), the specific chaperon of PC2, granine-like precursor of neuroendocrine protein proSAAS, the selective ligand of PC1, and serpin Spn4A (Serine Proteinase Inhibitor) of Drosophila melanogaster that inhibits PC2 and furin. By the methods of site-directed mutagenesis, the bioengineered inhibitors of PCs were also designed. Structures and properties of protein or peptide fragments as inhibitors of PCs were also discussed. Particularly, the properties of polyarginines and small peptides containing pseudopeptide bond at the scissile site a suitable peptide substrate were described. The inhibitory activity of non-peptide compounds such as derivatives of andrographolid from Andrographis paniculata (K(i) = 2.6-200 microM against furin), certain complexes of pyridine analogs with ions of Cu2+ or Zn2+ inhibiting furin with IC50 = 5-10 microM, derivatives of 2,5-dideoxy-streptamine containing several guanidine groups (K(i) = 6-812 nM for furin) and also a number of dicoumarols (K(i) = 1-185 microM against furin) and some flavonoids (with K(i) = 5-230 microM for furin) were reflected in the article. The effects of enediynyl-amino acids derivatives or their peptides (K(i) = 40 nM against furin) were considered. Inhibition of PC2 by N-acylated bicyclic guanidines (K(i) = 3.3-10 microM) or derivatives of pyrrolidin bispyperazines (K(i) = 0.54-10 microM) are considered too. Some of synthesized derivatives may serve as lead compounds for design of the specific inhibitors for individual PCs. PMID:22642118

  8. Structural Properties of Green Tea Catechins.

    Science.gov (United States)

    Botten, Dominic; Fugallo, Giorgia; Fraternali, Franca; Molteni, Carla

    2015-10-01

    Green tea catechins are polyphenols which are believed to provide health benefits; they are marketed as health supplements and are studied for their potential effects on a variety of medical conditions. However, their mechanisms of action and interaction with the environment at the molecular level are still not well-understood. Here, by means of atomistic simulations, we explore the structural properties of four green tea catechins, in the gas phase and water solution: specifically, (-)-epigallocatechin-3-gallate, which is the most abundant, (-)-epicatechin-3-gallate, (-)-epigallocatechin-3-O-(3-O-methyl)-gallate, and (-)-epigallocatechin. We characterize the free energy conformational landscapes of these catechins at ambient conditions, as a function of the torsional degrees of freedom of the pholyphenolic rings, determining the stable conformers and their connections. We show that these free energy landscapes are only subtly influenced by the interactions with the solvent and by the structural details of the polyphenolic rings. However, the number and position of the hydroxyl groups (or their sustituents) and the presence/absence of the galloyl moiety have significant impact on the selected catechin solvation shells and hydrogen bond capabilities, which are ultimately linked to their ability to interact with and affect the biological environment. PMID:26369298

  9. Miscibility and structure-property relationships in some novel polyolefins

    Science.gov (United States)

    Kamdar, Akshay Rajprakash

    In the first chapter, miscibility of homogeneous propylene/ethylene (P/E) copolymers of relatively narrow molecular weight distribution was studied as a function of constituent comonomer content. Polymers with up to 31 mol% ethylene were blended in pairs in order to vary the comonomer content difference. Copolymers of molecular weight about 200 kg mol-1 were miscible if the difference in ethylene content was less than about 18 mol%, and immiscible if the ethylene content difference was greater than about 20 mol%. Blends with constituent composition difference in the range of 18-20 mol% exhibited partial miscibility in the melt. In the second chapter, the effect of chain microstructure on the miscibility and phase behavior of ethylene-octene (EO) copolymer blends was studied. Binary blends of two statistical copolymers (EO/EO blends) that differed in comonomer content were compared with blends of an EO with an olefinic blocky ethylene-octene copolymer, OBC (EO/OBC blends). Two EOs of molecular weight about 100 kg/mol were miscible if the difference in octene content was less than about 10 mol% and immiscible if the octene content difference was greater than about 13 mol%. The blocky nature of the OBCs reduced the miscibility and broadened the partial miscibility window of EO/OBC blends compared to EO/EO blends. The EO/OBC blends were miscible if the octene content difference was less than 7 mol% and immiscible above 13 mol% octene content difference. In the third chapter, the adhesion of some ethylene-octene copolymers to polypropylene (PP) and high density polyethylene (HDPE) was studied in order to evaluate their suitability as compatibilizers for PP/HDPE blends. A one-dimensional model of the compatibilized blend was fabricated by layer-multiplying coextrusion. The microlayered tapes consisted of many alternating layers of PP and HDPE with a thin tie-layer inserted at each interface. The thickness of the tie-layer varied from 0.1 to 14 mum, which included thicknesses comparable to those of the interfacial layer in a compatibilized blend. A blocky copolymer (OBC) consistently exhibited better adhesion to PP than statistical copolymers (EO). Inspection of the crack-tip damage zone revealed a change from a continuous plastic damage zone in tie-layers 2 mum or thicker to a highly fibrillated damage zone in thinner tie-layers.

  10. Structure / property relationship for grain boundary engineering of polycrystals.

    Czech Academy of Sciences Publication Activity Database

    Lej?ek, Pavel; Hoffmann, S.; Paidar, Václav

    Auckland : The Institute of Materials Engineering Australasia, 2000 - (Zhang, K.; Pickering, K.; Xiong, X.), s. 615-620 [International Conference on Advanced Materials Processing /1./. Rotorua (NZ), 19.11.2000-23.11.2000] R&D Projects: GA ?R GA106/99/1178; GA ?R GA202/99/1665; GA MŠk OC 517.40 Grant ostatní: Copernicus(XX) ERBIC15 CT980812 Institutional research plan: CEZ:AV0Z1010914 Subject RIV: BM - Solid Matter Physics ; Magnetism

  11. Structure-property relationships in polyamide nanocomposites containing rubber particles.

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kotek, Ji?í; Kaprálková, Ludmila

    San Francisco : Delta Kunststoffe Company , 2004, s. 1-9. [Conference on Nanocomposites. San Francisco (US), 01.09.2004-03.09.2004] R&D Projects: GA ?R GA106/03/0679 Institutional research plan: CEZ:AV0Z4050913 Keywords : polyamide 6 * nanocomposite * toughness Subject RIV: CD - Macromolecular Chemistry

  12. 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.

  13. Preparation of polymeric nanocomposites and their structure-property relationships

    OpenAIRE

    Ristolainen-Virtanen, Noora

    2009-01-01

    Polymer nanocomposites were prepared by two different methods: (1) by melt blending polypropylene and layered clay in the presence of compatibilizers, and (2) by electrospinning poly(vinyl alcohol)/nanoclay, poly(vinyl alcohol)/nano titanium dioxide, and polyamide/nanoclay dispersions. In this work, the preparation of PP/nanoclay composites began by exchanging the originals of natural layered clay for octadecylamine and N-methylundecenylamine. This modification yielded the desired interc...

  14. 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

  15. Post-structural conceptualizations of power relationships in physiotherapy.

    Science.gov (United States)

    Eisenberg, Naomi R

    2012-08-01

    This paper uses a post-structuralist lens to explore the nature of power relationships within the patient-physical therapist relationship. To ground the discussion, I begin with an overview of the salient aspects of the traditional evolution of Western medicine. I then draw from the philosophy/history of Foucault to challenge traditional thinking and consider the applications to physiotherapy. The analysis reveals that the application of a Foucauldian frame of reference has the potential of modifying the therapeutic relationship to one that is more equitable as opposed to the hierarchical one. I conclude with a discussion of the implications for the development and education of physiotherapists. PMID:22765214

  16. Influence of surface and subsurface tillage on soil physical properties and soil/plant relationships of planted loblolly pine

    Energy Technology Data Exchange (ETDEWEB)

    D. L. Kelting; H. L. Allen

    2000-05-01

    Soil tillage can improve tree survival and growth by reducing competing vegetation, increasing nutrient availability, improving planting quality, and improving soil physical properties. The authors conducted a tillage study with competition control and nutrient amendments to isolate the physical effects of tillage on tree growth. The objectives of this study were to understand: (1) how tillage affects soil physical properties; (2) the relationships between these properties and root growth; (3) linkages between root growth response and aboveground growth; and (4) tillage effects on aboveground growth. Four replicates of a 2x2 factorial combination of surface (disking) and subsurface (subsoiling) were installed on a well-drained, clay-textured subsoil, soil located on the Piedmont of North Carolina. Disking improved soil physical properties (reduced bulk density and increased aeration porosity) in the surface 20-cm of soil. Subsoiling improved soil physical properties at all depths in the planting row, with improvements still noted at 60-cm from the planting row in the surface 10-cm of soil. Rooting patterns followed the changes in soil physical properties. Despite improvements in soil physical properties and changes in rooting patterns, aboveground tree growth was not affected by tillage. The results of this study point to the need for better diagnostics for identifying sites were tillage is appropriate in situations where fertilization and vegetation control are planned. Potential factors to consider are presence and abundance of old root channels, soil shrink/swell capacity, soil structure, presence and depth to root restricting layers, and historical precipitation records.

  17. Structural Effects on the Electronic and Electrochemical Properties of Polyarylenes

    Science.gov (United States)

    Child, Andrew David

    The structural modification of conducting polymers has proven to be an important factor in the tailoring of the electronic, electrochemical and solubility properties of these materials. This work describes the determination of structure property relationships in a series of thiophene, furan, and phenylene-based polymers by the investigation of the effects of pendant group substitution on their properties. Following a short introduction and experimental descriptions, the synthesis of the water soluble polymer poly(2,5-di(propoxy-3-sulfonate)-1,4-phenylene-alt-1,4 -phenylene) by a modified boronic acid coupling polymerization is described in Chapter 3. A model compound, which is essentially the phenyl-capped trimer of the polymer, was synthesized to assist in spectroscopic characterization. The polymer was found to be electroactive in various electrolytes and capable of both p-type and n-type redox doping. The effects of the propoxysulfonate pendants on the properties of the neutral polymer, aside from the tremendous change in solubility, were found to be minimal when compared with literature reports on unsubstituted poly(p-phenylene). Optoelectrochemical spectra demonstrate that the propoxy sulfonate derivative possesses a similar band gap to poly(p-phenylene). However, the pendants impart a stabilizing effect on the p-doped substituted polymer as observed by a lower degree of distortion and more symmetric band structure. The effects of substitution of the electronic properties of poly (1,4-bis(2-heterocycle)phenylenes) are outlined in Chapters 4 and 5, where the heterocycle employed is thiophene and furan respectively. The electrochemical behavior of these systems has been found to be highly dependent on the substituents. The alkoxy substituted derivatives of both systems show a decreased oxidation potential, along with lower band gaps, relative to the unsubstituted polymers. Long chain alkoxy substitution results in the separation of the neutral-to-polaron and polaron-to-bipolaron transition during electrochemical oxidation, as evidenced by the presence of two peaks in the cyclic voltammograms and appreciable paramagnetism observed during potential dependent EPR experiments.

  18. The Structure of the Relationship between Attention and Intelligence

    Science.gov (United States)

    Schweizer, Karl; Moosbrugger, Helfried; Goldhammer, Frank

    2005-01-01

    The relationship between attention and general intelligence was investigated considering the different types of attention: alertness, sustained attention, focused attention, attentional switching, divided attention, attention according to the supervisory attentional system, attention as inhibition, spatial attention, attention as planning,…

  19. 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.

  20. Phase relations, crystal structures and physical properties of nuclear fuels

    International Nuclear Information System (INIS)

    Phase relations, crystal structures and physical properties of the compounds for nuclear fuels are presented, including melting point, thermal expansion, diffusion and magnetic and electric properties. Emphasis is on oxides, carbides and nitrides of thorium, uranium and plutonium. (auth.)

  1. 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 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

  2. Structure Activity Relationships of ?v Integrin Antagonists for Pulmonary Fibrosis by Variation in Aryl Substituents.

    Science.gov (United States)

    Adams, James; Anderson, Edward C; Blackham, Emma E; Chiu, Yin Wa Ryan; Clarke, Thomas; Eccles, Natasha; Gill, Luke A; Haye, Joshua J; Haywood, Harvey T; Hoenig, Christian R; Kausas, Marius; Le, Joelle; Russell, Hannah L; Smedley, Christopher; Tipping, William J; Tongue, Tom; Wood, Charlotte C; Yeung, Jason; Rowedder, James E; Fray, M Jonathan; McInally, Thomas; Macdonald, Simon J F

    2014-11-13

    Antagonism of ?v?6 is emerging as a potential treatment of idiopathic pulmonary fibrosis based on strong target validation. Starting from an ?v?3 antagonist lead and through simple variation in the nature and position of the aryl substituent, the discovery of compounds with improved ?v?6 activity is described. The compounds also have physicochemical properties commensurate with oral bioavailability and are high quality starting points for a drug discovery program. Compounds 33S and 43E1 are pan ?v antagonists having ca. 100 nM potency against ?v?3, ?v?5, ?v?6, and ?v?8 in cell adhesion assays. Detailed structure activity relationships with these integrins are described which also reveal substituents providing partial selectivity (defined as at least a 0.7 log difference in pIC50 values between the integrins in question) for ?v?3 and ?v?5. PMID:25408832

  3. Relationship of fiber properties to vortex yarn quality via partial least squares

    Science.gov (United States)

    The Cotton Quality Research Station (CQRS) of the USDA-ARS, recently completed a comprehensive study of the relationship of cotton fiber properties to the quality of spun yarn. The five year study, began in 2001, utilized commercial variety cotton grown, harvested and ginned in each of three major ...

  4. The contribution of the strength and structure of extratropical cyclones to observed cloud-aerosol relationships

    OpenAIRE

    Grandey, B. S.; Stier, P; Grainger, R. G.; Wagner, T. M.

    2013-01-01

    Meteorological conditions may drive relationships between aerosol and cloud-related properties. It is important to account for the meteorological contribution to observed cloud–aerosol relationships in order to improve understanding of aerosol–cloud–climate interactions. A new method of investigating the contribution of meteorological covariation to observed cloud–aerosol relationships is introduced. Other studies have investigated the contribution of local meteorology to cl...

  5. Relationships between inherent optical properties in the Baltic Sea for application to the underwater imaging problem

    Directory of Open Access Journals (Sweden)

    S?awomir Sagan

    2013-02-01

    Full Text Available Statistical relationships between coefficients of light attenuation, scattering and backscattering at wavelength 550 nm derived from series of optical measurements performed in Baltic Sea waters are presented. The relationships were derived primarily to support data analysis from underwater imaging systems. Comparison of these relations with analogous empirical data from the Atlantic and Pacific Oceans shows that the two sets of relationships are similar, despite the different water types and the various experimental procedures and instrumentation applied. The apparently universal character of the relationships enables an approximate calculation of other optical properties and subsequently of the contrast, signal/noise ratio, visibility range and spatial resolution of underwater imaging systems based on attenuation coefficients at wavelength 550 nm only.

  6. Synthesis, structure, and properties of azatriangulenium salts

    DEFF Research Database (Denmark)

    Laursen, B.W.; Krebs, Frederik C

    2001-01-01

    A general synthetic route to novel nitrogen-bridged heterocyclic carbenium ions of the acridinium and triangulenium type has been developed and investigated. The synthetic method is based on nucleophilic aromatic substitution (SNAr) on the tris(2,6-dimethoxyphenyl)carbenium ion (1) with primary amines and, by virtue of its stepwise and irreversible nature, provides a powerful tool for the preparation of a wide variety of new heterocyclic carbenium salts. Several derivatives of the three new oxygen- and/or nitrogen-bridged triangulenium salts, azadioxa- (6), diazaoxa- (7), and triazatriangulenium (4), have been synthesized and their physicochemical properties have been investigated. Crystal structures for compounds 2 b-PF6: 2d-PF6, 4b-BF4, 4c-BF4, 6e-BF4, and 8 are reported. The different packing modes found for the triazatriagulenium salts are discussed in relation to the electrostatic and space-filling requirements of the ions. The stabilities of the cations 6a. 7b, and 4a, as expressed by their pK(R+) values, have been determined in strongly basic nonaqueous solution by use of the C- acidity function; the values obtained were 14.5, 19.4, and 23.7, respectively. This study further implied that the C- scale in its present form is unsuitable for the precise determination of pK(R+) values beyond 22.

  7. Quantitative structure fate relationships for multimedia environmental analysis

    OpenAIRE

    Martínez Brito, Izacar Jesús

    2010-01-01

    Key physicochemical properties for a wide spectrum of chemical pollutants are unknown. This thesis analyses the prospect of assessing the environmental distribution of chemicals directly from supervised learning algorithms using molecular descriptors, rather than from multimedia environmental models (MEMs) using several physicochemical properties estimated from QSARs. Dimensionless compartmental mass ratios of 468 validation chemicals were compared, in logarithmic units, between: a) SimpleBox...

  8. Evaluating the effectiveness of common structures in property portfolio construction

    OpenAIRE

    Devaney, S.

    2003-01-01

    A good portfolio structure enables an investor to diversify more effectively and understand systematic influences on their performance. However, in the property market, the choice of structure is affected by data constraints and convenience. Using individual return data, this study tests the hypothesis that some common structures in the UK do not explain a significant amount about property returns. It is found that, in the periods studied, not all the structures were effective and, for the a...

  9. Quantum properties of a cyclic structure based on tripolar fields

    OpenAIRE

    Yershov, V. N.

    2006-01-01

    The properties of cyclic structures (toroidal oscillators) based on classical tripolar (colour) fields are discussed, in particular, of a cyclic structure formed of three colour-singlets spinning around a ring-closed axis. It is shown that the helicity and handedness of this structure can be related to the quantum properties of the electron. The symmetry of this structure corresponds to the complete cycle of ${2/3}\\pi$-rotations of its constituents, which leads to the exact ...

  10. Creativity: Its Relationship to Single Parent Family Structure.

    Science.gov (United States)

    Jenkins, Jeanne E.

    The insecurities generated in children by stressful environmental changes can compromise their receptivity to learning and their attitude toward school. Studies examining divorce outcomes focus primarily on two cognitive indicators: achievement and intelligence. This study explored the relationship between creative thinking components and family…

  11. Relationship between organizational structure and creativity in teaching hospitals

    OpenAIRE

    REZAEE, RITA; MARHAMATI, SAADAT; NABEIEI, PARISA; MARHAMATI, RAHELEH

    2014-01-01

    Introduction: Organization structure and manpower constitute two basic components of anorganization and both are necessary for stablishing an organization. The aim of this survey was to investigate the type of the organization structure (mechanic and organic) from viewpoint of senior and junior managers in Shiraz teaching hospitals and creativity in each of these two structures.

  12. The relationship between molecular structure and biological activity of alkali metal salts of vanillic acid: Spectroscopic, theoretical and microbiological studies

    Science.gov (United States)

    ?wis?ocka, Renata; Piekut, Jolanta; Lewandowski, W?odzimierz

    In this paper we investigate the relationship between molecular structure of alkali metal vanillate molecules and their antimicrobial activity. To this end FT-IR, FT-Raman, UV absorption and 1H, 13C NMR spectra for lithium, sodium, potassium, rubidium and caesium vanillates in solid state were registered, assigned and analyzed. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris, Bacillus subtilis and Candida albicans. In order to evaluate the dependence between chemical structure and biological activity of alkali metal vanillates the statistical analysis was performed for selected wavenumbers from FT-IR spectra and parameters describing microbial activity of vanillates. The geometrical structures of the compounds studied were optimized and the structural characteristics were determined by density functional theory (DFT) using at B3LYP method with 6-311++G** as basis set. The obtained statistical equations show the existence of correlation between molecular structure of vanillates and their biological properties.

  13. 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.

  14. Structure-activity relationship of the pro- and anticoagulant effects of Fucus vesiculosus fucoidan.

    Science.gov (United States)

    Zhang, Z; Till, S; Jiang, C; Knappe, S; Reutterer, S; Scheiflinger, F; Szabo, C M; Dockal, M

    2014-03-01

    Fucoidan is a highly complex sulfated polysaccharide commonly extracted from brown seaweed. In addition to their many biological activities, fucoidans have recently been demonstrated to inhibit or increase coagulation at different concentration ranges. Their structural features, i.e. molecular weight (Mw), Mw distribution, degree of sulfation, monosaccharide composition, and different linkages, are known to affect these activities. Therefore, structure-activity relationship (SAR) analysis of fucoidan is crucial for its potential use as a procoagulant. In this study, Fucus vesiculosus (F.v.) fucoidan was fractionated by charge and size as well as over- and desulfated to different degrees to yield preparations with various structural properties. The fractions' pro- and anticoagulant activities were assessed by calibrated automated thrombography (CAT) and activated partial thromboplastin time(aPTT) assays. Binding to and inhibition of the anticoagulant protein tissue factor pathway inhibitor (TFPI) and the ability to activate coagulation via the contact pathway were also investigated. This paper discusses the impact of charge density, size, and sugar composition on fucoidan's pro- and anticoagulant activities. Fucoidan requires a minimal charge density of 0.5 sulfates per sugar unit and a size of 70 sugar units to demonstrate desired procoagulant activities for improvement of haemostasis in factor VIII/factor IX-deficient plasma. PMID:24285223

  15. 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).

  16. Correlations between structural and mechanical properties of human trabecular femur bone.

    Science.gov (United States)

    Nikodem, Anna

    2012-01-01

    In this article, the author presents mathematical relationships between the structural and mechanical properties of cancellous human bone tissue obtained by experimental analysis of specimens. Bone tissue material can adjust its internal structure to the existing loading conditions. The mechanical properties affect the structural properties but changes in structural properties likewise cause changes in the mechanical properties of the tissue. In normal tissue, the processes of tissue construction, destruction, and reconstruction are mutually balanced and complementary; if that balance is disturbed, lesions can occur. Therefore, normal bone tissue and pathologically changed tissue (osteoporosis and osteoarthrosis) coming from the area of human femoral head were examined. The structural properties of cancellous tissue specimens were determined non-destructively for three-dimensional reconstructions with the use of modern micro-CT methods. The mechanical properties of the specimens were determined by an uniaxial compression test in three orthogonal directions. Next, in order to specify the compressive strength, a failure test was conducted in the direction perpendicular to the neck-shaft angle of the hip joint. PMID:22793376

  17. 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 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)

  18. The Role of Structural Bonds in the Development of Strategic Buyer-Supplier Relationships

    OpenAIRE

    King, Oscar; Yiyen, Vinyoh

    2012-01-01

    Background: The need to cut costs, save money, become profitable, be innovative, improve product quality and be responsive to customers’ demands is encouraging some organizations to form strategic relationships with suppliers. In achieving this, certain joint investments, called structural bonds, are developed within the relationship life-cycle. Although the bonds tend to tie down the partners and also create impediments for the termination of the relationship, they inevitably contribute to t...

  19. 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.…

  20. 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...

  1. 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. (author)

  2. 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

  3. 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…

  4. Measurements of rheological and structural properties of lubricant films

    Science.gov (United States)

    Mriziq, Khaled S.; Dai, Horn-Ji; Dadmun, Mark D.; Cochran, Hank D.

    2002-03-01

    Understanding the rheological and structural properties of long-chain molecules presents fundamental challenges and yet is of immense technological importance. Most common, experimental techniques available for studying the rheological and structural properties are cone-plate and Couette geometries. However, these techniques are limited to moderate shear rate because of the difficulty in removing the viscous heat. A high shear rate home-built parallel-plate rotational rheometer has been used for measurements of rheological and structural properties. The design is similar to a hard disk drive; a thin film is sheared between optically transparent disc and slider. While the rheological properties of the polymer thin film can be obtained from the stresses on the slider, small-angel light scattering and other optical techniques can investigate the sample structure. The film thickness is monitored using a capacitive method. Perfluoropolyether lubricant films were used to test the apparatus and investigate the rheological and structural properties of the films.

  5. 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.)

  6. 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...

  7. 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

  8. 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.

  9. Coupled analysis of in vitro and histology tissue samples to quantify structure-function relationship

    OpenAIRE

    Evrim, Acar Ataman; Plopper, George E.; Yener, Bülent

    2012-01-01

    The structure/function relationship is fundamental to our understanding of biological systems at all levels, and drives most, if not all, techniques for detecting, diagnosing, and treating disease. However, at the tissue level of biological complexity we encounter a gap in the structure/function relationship: having accumulated an extraordinary amount of detailed information about biological tissues at the cellular and subcellular level, we cannot assemble it in a way that explains the corres...

  10. 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...

  11. 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...

  12. A robust structure-activity relationship (SAR) model for esters that cause skin irritation in humans.

    Science.gov (United States)

    Smith, J S; Macina, O T; Sussman, N B; Luster, M I; Karol, M H

    2000-05-01

    A structure-activity relationship (SAR) model has been developed to discriminate skin irritant from nonirritant esters. The model is based on the physicochemical properties of 42 esters that were tested in humans for skin irritation. Nineteen physicochemical parameters that represent transport, electronic, and steric properties were calculated for each chemical. Best subsets regression analysis indicated candidate models for further analysis. Regression analyses identified significant models (p parameters among ten submodels generated using multiple random sampling of the database. The sensitivity of the ten models, evaluated by "leave-one-out" cross-validation, ranged from 0. 846 to 0.923, with a mean of 0.885 +/- 0.025 (95% CI). The specificity ranged from 0.615 to 0.923, with a mean of 0.738 +/- 0.06 (CI). Compared with nonirritant esters, irritant esters had lower density, lower water solubility, lower sum of partial positive charges, higher Hansen hydrogen bonding parameter, and higher Hansen dispersion parameter. The results indicate that physicochemical features of esters contribute to their ability to cause skin irritation in humans, and that chemical partitioning into the epidermis and intermolecular reactions are likely important components of the response. This model is applicable for prediction of human irritation of esters yet untested. PMID:10788576

  13. Relationship between nanostructure and dielectric response of lead scandium tantalate - (I) Structure and domain textures

    International Nuclear Information System (INIS)

    Three ceramic preparations of lead scandium tantalate were chosen for the present study because they exhibit three different relaxor-type dielectric response behaviours. Two preparations, made in lead-rich atmospheres, so as to conserve virtually 100% occupancy of the perovskite (ABO3) A sites, were annealed or quenched so as to yield extreme values for the long-range order parameter (s) for (Sc,Ta) ordering on the perovskite B site; thus s=0.93 and 0.10 for pst-o and pst-d, respectively. The third preparation, made in the classical way in the expectation that there would be significant levels of Pb atom vacancies, allowed earlier literature results for the dielectric response to be reproduced (sample pst-def; s=0.20).Results of high-resolution and dark-field transmission electron microscopic studies and electrical property measurements are compared in order to elucidate, as directly as possible, the structure-property relationships. The results of Monte Carlo and next-nearest-neighbour Ising model simulations for the evolution of the chemical domain textures are compared with the experimental dark-field images. This allows several distinct types of chemical defect clusters to be characterized, the existence of both charged and neutral defects are implied by the simulations. A discussion of the role played by such defects in producing random local fields and finally determining the frequency dependence of the dielectric response completes the paper. ((orig.))

  14. Neuromorphic hardware databases for exploring structure-function relationships in the brain.

    Science.gov (United States)

    Breslin, C; O'Lenskie, A

    2001-08-29

    Neuromorphic hardware is the term used to describe full custom-designed integrated circuits, or silicon 'chips', that are the product of neuromorphic engineering--a methodology for the synthesis of biologically inspired elements and systems, such as individual neurons, retinae, cochleas, oculomotor systems and central pattern generators. We focus on the implementation of neurons and networks of neurons, designed to illuminate structure-function relationships. Neuromorphic hardware can be constructed with either digital or analogue circuitry or with mixed-signal circuitry--a hybrid of the two. Currently, most examples of this type of hardware are constructed using analogue circuits, in complementary metal-oxide-semiconductor technology. The correspondence between these circuits and neurons, or networks of neurons, can exist at a number of levels. At the lowest level, this correspondence is between membrane ion channels and field-effect transistors. At higher levels, the correspondence is between whole conductances and firing behaviour, and filters and amplifiers, devices found in conventional integrated circuit design. Similarly, neuromorphic engineers can choose to design Hodgkin-Huxley model neurons, or reduced models, such as integrate-and-fire neurons. In addition to the choice of level, there is also choice within the design technique itself; for example, resistive and capacitive properties of the neuronal membrane can be constructed with extrinsic devices, or using the intrinsic properties of the materials from which the transistors themselves are composed. So, silicon neurons can be built, with dendritic, somatic and axonal structures, and endowed with ionic, synaptic and morphological properties. Examples of the structure-function relationships already explored using neuromorphic hardware include correlation detection and direction selectivity. Establishing a database for this hardware is valuable for two reasons: first, independently of neuroscientific motivations, the field of neuromorphic engineering would benefit greatly from a resource in which circuit designs could be stored in a form appropriate for reuse and re-fabrication. Analogue designers would benefit particularly from such a database, as there are no equivalents to the algorithmic design methods available to designers of digital circuits. Second, and more importantly for the purpose of this theme issue, is the possibility of a database of silicon neuron designs replicating specific neuronal types and morphologies. In the future, it may be possible to use an automated process to translate morphometric data directly into circuit design compatible formats. The question that needs to be addressed is: what could a neuromorphic hardware database contribute to the wider neuroscientific community that a conventional database could not? One answer is that neuromorphic hardware is expected to provide analogue sensory-motor systems for interfacing the computational power of symbolic, digital systems with the external, analogue environment. It is also expected to contribute to ongoing work in neural-silicon interfaces and prosthetics. Finally, there is a possibility that the use of evolving circuits, using reconfigurable hardware and genetic algorithms, will create an explosion in the number of designs available to the neuroscience community. All this creates the need for a database to be established, and it would be advantageous to set about this while the field is relatively young. This paper outlines a framework for the construction of a neuromorphic hardware database, for use in the biological exploration of structure-function relationships. PMID:11545701

  15. 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.

  16. Relationship between micro-porosity and tensile properties of 6063 alloy

    OpenAIRE

    Li Xiehua; He Lizi; Zhu Pei

    2013-01-01

    The micro-porosity is usually present in the as-cast microstructure, which decreases the tensile strength and ductility and therefore limit the application of cast aluminum parts. Although much work has been done to investigate the effects of various casting parameters on the formation of porosity in various aluminum alloys, up to now, little information has been available for the relationship between micro-porosity and tensile properties of 6063 alloy. In this study, the influences of size a...

  17. 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 fo...

  18. Roles of Multi-Walled Structures in Thermal Transport Properties of Nanotubes

    Science.gov (United States)

    Hata, Tomoyuki; Kawai, Hiroki; Jono, Ryota; Yamashita, Koichi

    2015-03-01

    The molecular structures of carbon nanotubes are thought to be deeply related with various physical properties. Understanding the relationship is one of the challenges in designing potential materials. In this research, we theoretically investigated the thermal transport properties of carbon nanotubes, focusing the multi-walled structures. We investigated the thermal conductance of the double-walled carbon nanotubes (DWCNTs) by using the nonequilibrium Green's function method. It is found that the inter-layer interaction causes the suppression of thermal conductance at low temperature. The analysis of the transmission coefficients revealed that this suppression was attributed to the energy shifts of the normal modes from the synchronized vibrations. The mechanism of such energy shifts is examined by the coupled vibration model with the parameters extracted from our simulations, and we grasp the multi-wall effects on the thermal transport properties of the nanotube structures.

  19. Structure-Function Relationships of Human Milk Oligosaccharides123

    OpenAIRE

    Bode, Lars; Jantscher-Krenn, Evelyn

    2012-01-01

    Human milk contains more than a hundred structurally distinct oligosaccharides. In this review, we provide examples of how the structural characteristics of these human milk oligosaccharides (HMO) determine functionality. Specific ?1–2-fucosylated HMO have been shown to serve as antiadhesive antimicrobials to protect the breast-fed infant against infections with Campylobacter jejuni, one of the most common causes of bacterial diarrhea. In contrast, ?1–2-fucosylation may abolish the beneficial...

  20. 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.

  1. 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

  2. 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: 1.637, year: 2014 http:// library .utia.cas.cz/separaty/2015/MTR/jirousek-0442412.pdf

  3. Demographic Structure and the Security of Property Rights in Developing Countries – An Empirical Exploration

    OpenAIRE

    Harms, Philipp; an de Meulen, Philipp

    2010-01-01

    It is often argued that countries with a high population share of children and young workers should attract large capital inflows from aging industrialized economies. However, many of these countries deter foreign investors by a high risk of creeping or outright expropriation. In this paper we explore whether the correlation between countries' demographic structure and the perceived security of property rights reflects a causal relationship. We show that, once we control for other potential d...

  4. Constraining the density dependence of the symmetry energy with nuclear structure properties

    International Nuclear Information System (INIS)

    In this work, we review a few structural properties in finite nuclei and nuclear matter that are sensitive to differences in the symmetry energy, and discuss mechanisms that can enhance the sensitivity to differences in the symmetry energy with the relativistic mean-field model. Emphasis has been placed on the establishment of the relationship between the deexcitation energy of superdeformed secondary minima and the density dependence of the symmetry energy. (author)

  5. 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.

  6. Properties and Origins of Protein Secondary Structure

    OpenAIRE

    Socci, Nicholas D.; Bialek, William S.; Onuchic, Jose' Nelson

    1994-01-01

    Proteins contain a large fraction of regular, repeating conformations, called secondary structure. A simple, generic definition of secondary structure is presented which consists of measuring local correlations along the protein chain. Using this definition and a simple model for proteins, the forces driving the formation of secondary structure are explored. The relative role of energy and entropy are examined. Recent work has indicated that compaction is sufficient to creat...

  7. 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.

  8. 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.

  9. 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

  10. 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 carcinogenesis. Finally, and most importantly, we demonstrate the potentialities of this approach towards the recognition of structural alerts for carcinogenicity predictions

  11. Structure-activity relationship and comparative docking studies for cycloguanil analogs as PfDHFR-TS inhibitors.

    Science.gov (United States)

    Sivaprakasam, Prasanna; Tosso, Perrer N; Doerksen, Robert J

    2009-07-01

    Drug resistance acquired by Plasmodium falciparum (Pf) is a major problem in the treatment and control of malaria. One of the major examples of drug resistance is that caused by mutations in the active site of dihydrofolate reductase (DHFR) of Pf (PfDHFR-TS). A double mutation, A16V+S108T, is specific for resistance to the marketed drug cycloguanil. In this study, we used 58 cycloguanil (2,4-diamino-1,6-dihydro-1,3,5-triazine) derivatives to explore the relationship between various physicochemical properties and reported binding affinity data on wild-type and mutant-type A16V+S108T. Using the Hansch 2D-quantitative structure-activity relationship method, we obtained a parabolic relationship of hydrophobicity of substituents at the N1-phenyl ring with the wild-type binding affinity data. Hydrophobicity being a key property for wild-type binding affinity data, we found steric factors to be crucial for A16V+S108T mutant resistance. We investigated FlexX, GOLD, Glide and Molegro virtual docking programs and 13 different scoring functions on 10 of the cycloguanil derivatives to evaluate which program was best for reproducing the experimental binding mode and correlating the docking scores with the reported binding affinity data. We identified GOLD, using its GoldScore fitness function, as the most accurate docking program for predicting binding affinity data of cycloguanil derivatives to DHFR and Molegro virtual docker, with its template docking algorithm and MolDock [GRID] scoring function, as most accurate for reproducing the experimental binding mode of a reference ligand that is structurally similar to the cycloguanil derivatives studied. We also report an interaction index which best describes the structure-activity relationships exhibited by these analogs in terms of PfDHFR-TS active site interactions. PMID:19588935

  12. Structure and properties of diamond and diamond-like films

    Energy Technology Data Exchange (ETDEWEB)

    Clausing, R.E. [Oak Ridge National Lab., TN (United States)

    1993-01-01

    This section is broken into four parts: (1) introduction, (2) natural IIa diamond, (3) importance of structure and composition, and (4) control of structure and properties. Conclusions of this discussion are that properties of chemical vapor deposited diamond films can compare favorably with natural diamond, that properties are anisotropic and are a strong function of structure and crystal perfection, that crystal perfection and morphology are functions of growth conditions and can be controlled, and that the manipulation of texture and thereby surface morphology and internal crystal perfection is an important step in optimizing chemically deposited diamond films for applications.

  13. Children's Working Memory: Its Structure and Relationship to Fluid Intelligence

    Science.gov (United States)

    Hornung, Caroline; Brunner, Martin; Reuter, Robert A. P.; Martin, Romain

    2011-01-01

    Working memory (WM) has been predominantly studied in adults. The insights provided by these studies have led to the development of competing theories on the structure of WM and conflicting conclusions on how strongly WM components are related to higher order thinking skills such as fluid intelligence. However, it remains unclear whether and to…

  14. Complex relationships between structural and functional brain connectivity

    OpenAIRE

    Uddin, Lucina Q.

    2013-01-01

    In recent work, O’Reilly and colleagues demonstrate relatively intact interhemispheric functional connectivity in a macaque brain in the absence of major commissural fibers. This work adds to a growing body of literature challenging the notion that structural and functional brain connectivity metrics are related in a straightforward manner.

  15. Relationship between Plant Species Covers and Soil Chemical Properties in Poorly Controlled Waste Landfill Sites

    Directory of Open Access Journals (Sweden)

    Eun Ju Lee

    2007-02-01

    Full Text Available The relationships between the cover of herbaceous species and 15 soil chemical properties(organic carbon contents, total N, available P, exchangeable K, Na, Ca and Mg, HCl-extractable Cd, Cr, Cu,Fe, Mn, Ni, Pb and Zn in nine poorly controlled waste landfill sites in Korea were examined by correlationanalysis and multiple regression equations. Species showed different patterns of correlation between their covervalues and soil chemical properties. The cover of Ambrosia artemisiifolia var. elatior, Aster subulatus var. sandwicensisand Erechtites hieracifolia were negatively correlated with the contents of Fe, Mn and Ni within landfillsoils. Total cover of all species in quadrats was positively correlated with the contents of Cd and negativelycorrelated with the contents of Mn and Fe from stepwise regression analysis with 15 soil properties. Canonicalcorrespondence analysis demonstrated that the distribution of native and exotic plants on poorly controlledlandfills was significantly influenced by the contents of Na and Ca in soils, respectively.

  16. Predicting physical-chemical properties of compounds from molecular structures by recursive neural networks.

    Science.gov (United States)

    Bernazzani, Luca; Duce, Celia; Micheli, Alessio; Mollica, Vincenzo; Sperduti, Alessandro; Starita, Antonina; Tiné, Maria Rosaria

    2006-01-01

    In this paper, we report on the potential of a recently developed neural network for structures applied to the prediction of physical chemical properties of compounds. The proposed recursive neural network (RecNN) model is able to directly take as input a structured representation of the molecule and to model a direct and adaptive relationship between the molecular structure and target property. Therefore, it combines in a learning system the flexibility and general advantages of a neural network model with the representational power of a structured domain. As a result, a completely new approach to quantitative structure-activity relationship/quantitative structure-property relationship (QSPR/QSAR) analysis is obtained. An original representation of the molecular structures has been developed accounting for both the occurrence of specific atoms/groups and the topological relationships among them. Gibbs free energy of solvation in water, Delta(solv)G degrees , has been chosen as a benchmark for the model. The different approaches proposed in the literature for the prediction of this property have been reconsidered from a general perspective. The advantages of RecNN as a suitable tool for the automatization of fundamental parts of the QSPR/QSAR analysis have been highlighted. The RecNN model has been applied to the analysis of the Delta(solv)G degrees in water of 138 monofunctional acyclic organic compounds and tested on an external data set of 33 compounds. As a result of the statistical analysis, we obtained, for the predictive accuracy estimated on the test set, correlation coefficient R = 0.9985, standard deviation S = 0.68 kJ mol(-1), and mean absolute error MAE = 0.46 kJ mol(-1). The inherent ability of RecNN to abstract chemical knowledge through the adaptive learning process has been investigated by principal components analysis of the internal representations computed by the network. It has been found that the model recognizes the chemical compounds on the basis of a nontrivial combination of their chemical structure and target property. PMID:16995734

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

    OpenAIRE

    Haji A.; Nasouri K.; Mousavi Shoushtari A.; Kaflou A.

    2013-01-01

    The dispersion stability behavior of single walled carbon nanotube (SWCNT) has important effects on morphological and mechanical properties of SWCNT/polymer composite nanofibers. The effects of SWCNTs incorporation on the morphological and structural developments and the relation between this develop-ments and mechanical properties of the polyacrylonitrile (PAN) nanofibers were demonstrated. The uni-form, stable dispersion and well oriented SWCNT within the PAN matrix were achieved through us...

  18. 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…

  19. Syntheses and absorption-structure relationships of some new photosensitizer cyanine dyes

    Indian Academy of Sciences (India)

    H A Shindy; A I M Koraiem

    2002-04-01

    New biheterocyclic compound was synthesized as starting material to prepare new photosensitizers mono-, tri-, substituted tri-, azadimethine and mixed cyanine dyes. Absorption-structure relationship of the synthesized cyanine dyes were determined by studying their electronic spectral behaviour in ethanol. The structure of the compounds were identified by elemental analysis, IR and 1H NMR spectral data.

  20. Reflecting on the Father: Childhood Family Structure and Women's Paternal Relationships

    Science.gov (United States)

    Krampe, Edythe M.; Newton, Rae R.

    2012-01-01

    The researchers examined childhood family structure, age, and race/ethnicity as correlates of paternal relationships using the Father Presence Questionnaire. The sample consisted of 788 adult women aged 18 to 88 years from ethnically diverse backgrounds. The most consistent finding was the effect of family structure on participants' evaluations of…

  1. When Friends Leave: A Structural Analysis of the Relationship between Turnover and Stayers' Attitudes.

    Science.gov (United States)

    Krackhardt, David; Porter, Lyman W.

    1985-01-01

    This paper investigates the effect that turnover in an organization has on the attitudes of those who remain. A longitudinal study of three fast-food restaurants explored this relationship against the background of the social network structures in each site. Results underscore the importance of structural context in studying microphenomena. (TE)

  2. Structure and properties of "nematically ordered" aerogels

    Science.gov (United States)

    Asadchikov, V. E.; Askhadullin, R. Sh.; Volkov, V. V.; Dmitriev, V. V.; Kitaeva, N. K.; Martynov, P. N.; Osipov, A. A.; Senin, A. A.; Soldatov, A. A.; Chekrygina, D. I.; Yudin, A. N.

    2015-04-01

    The microstructure, specific area, and mechanical properties of various samples of "nematically ordered" aerogels whose strands are almost parallel to each other at macroscopic distances have been studied. The strong anisotropy of such aerogels distinguishes them from standard aerogels, which are synthesized by solgel technology, and opens new possibilities for physical experiments.

  3. The structural and electronic properties of germanium clathrates

    OpenAIRE

    Zhao, Jijun; Buldum, Alper; Lu, Jianping; Fong, C. Y.

    1999-01-01

    The structural and electronic properties of germanium clathrates Ge$_{46}$ and K$_8$Ge$_{46}$ are studied by first principles calculations within the local density approximation. The equilibrium structures are obtained by {\\em ab initio} pseudopotential calculation combined with dynamic minimizations. The clathrate structure is found as a low energy phase for germanium. The electronic band structures for Ge$_{46}$ clathrates are calculated and the band gap is found to be con...

  4. Structure and Properties of Rare earth Neodymium Zinc Titanate

    OpenAIRE

    Khamoushi, Kouros

    2015-01-01

    The dielectric properties and phase grouping of Rare earth Neodymium Zinc Titanate (NZT) was investigated in this research. The result shows that it is distrustful to be a stable perovskite structure, in fact something comparable to Ilmenite structure, however the further research shows that the monoclinic structure can be purposed for NZT. The Modelling and simulation were used in this research to define the atomic position and crystal structure of NZT. These compositions h...

  5. Structural properties of crumpled cream layers

    International Nuclear Information System (INIS)

    The cream layer is a complex heterogeneous material of biological origin which forms spontaneously at the air-milk interface. Here, the crumpling of a single cream layer packing under its own weight at room temperature in a three-dimensional space is studied. The structure obtained in these circumstances has a low volume fraction and anomalous fractal dimensions. Direct means and noninvasive NMR imaging techniques are used to investigate the internal and the external structures of these systems

  6. Role of sequence and structural polymorphism on the mechanical properties of amyloid fibrils.

    Science.gov (United States)

    Yoon, Gwonchan; Lee, Myeongsang; Kim, Jae In; Na, Sungsoo; Eom, Kilho

    2014-01-01

    Amyloid fibrils playing a critical role in disease expression, have recently been found to exhibit the excellent mechanical properties such as elastic modulus in the order of 10 GPa, which is comparable to that of other mechanical proteins such as microtubule, actin filament, and spider silk. These remarkable mechanical properties of amyloid fibrils are correlated with their functional role in disease expression. This suggests the importance in understanding how these excellent mechanical properties are originated through self-assembly process that may depend on the amino acid sequence. However, the sequence-structure-property relationship of amyloid fibrils has not been fully understood yet. In this work, we characterize the mechanical properties of human islet amyloid polypeptide (hIAPP) fibrils with respect to their molecular structures as well as their amino acid sequence by using all-atom explicit water molecular dynamics (MD) simulation. The simulation result suggests that the remarkable bending rigidity of amyloid fibrils can be achieved through a specific self-aggregation pattern such as antiparallel stacking of ? strands (peptide chain). Moreover, we have shown that a single point mutation of hIAPP chain constituting a hIAPP fibril significantly affects the thermodynamic stability of hIAPP fibril formed by parallel stacking of peptide chain, and that a single point mutation results in a significant change in the bending rigidity of hIAPP fibrils formed by antiparallel stacking of ? strands. This clearly elucidates the role of amino acid sequence on not only the equilibrium conformations of amyloid fibrils but also their mechanical properties. Our study sheds light on sequence-structure-property relationships of amyloid fibrils, which suggests that the mechanical properties of amyloid fibrils are encoded in their sequence-dependent molecular architecture. PMID:24551113

  7. CLEFMA- An Anti-Proliferative Curcuminoid from Structure Activity Relationship Studies on 3,5-bis(benzylidene)-4-piperidones

    OpenAIRE

    Lagisetty, Pallavi; Vilekar, Prachi; Sahoo, Kaustuv; ANANT, SHRIKANT; Awasthi, Vibhudutta

    2010-01-01

    3,5-bis(benzylidene)-4-piperidones are being advanced as synthetic analogs of curcumin for anticancer and anti-inflammatory properties. We performed structure-activity relationship studies, by testing several synthesized 3,5-bis(benzylidene)-4-piperidones for anti-proliferative activity in lung adenocarcinoma H441 cells. Compared to the lead compound 1, or 3,5-bis(2-fluorobenzylidene)-4-piperidone, five compounds were found to be more potent (IC50 < 30 ?M), and sixteen compounds possessed red...

  8. Phenethyl nicotinamides, a novel class of Na(V)1.7 channel blockers: structure and activity relationship.

    Science.gov (United States)

    Kers, Inger; Macsari, Istvan; Csjernyik, Gabor; Nylöf, Martin; Skogholm, Karin; Sandberg, Lars; Minidis, Alexander; Bueters, Tjerk; Malmborg, Jonas; Eriksson, Anders B; Lund, Per-Eric; Venyike, Elisabet; Luo, Lei; Nyström, Jan-Erik; Besidski, Yevgeni

    2012-10-01

    The Na(V)1.7 ion channel is an attractive target for development of potential analgesic drugs based on strong genetic links between mutations in the gene coding for the channel protein and inheritable pain conditions. The (S)-N-chroman-3-ylcarboxamide series, exemplified by 1, was used as a starting point for development of new channel blockers, resulting in the phenethyl nicotinamide series. The structure and activity relationship for this series was established and the metabolic issues of early analogues were addressed by appropriate substitutions. Compound 33 displayed acceptable overall in vitro properties and in vivo rat PK profile. PMID:22939696

  9. Thermodynamical properties and thermoelastic coupling of complex macroscopic structure

    International Nuclear Information System (INIS)

    Gross qualitative/quantitative analysis about thermodynamical properties and thermoelastic coupling (or elastocaloric effect) of complex macroscopic structure (running shoes) is performed by infrared camera. The experimental results showed the achievability of a n industrial research project

  10. Relationship between rupture life and creep properties of 2 1/4 Cr--1 Mo steel

    International Nuclear Information System (INIS)

    Several investigators have demonstrated empirical relationships between creep and rupture properties for various metals and alloys. Empirical relationships between the rupture life, the minimum creep rate, and the time to the end of steady-state creep (start of tertiary creep) for four heats of normalized-and-tempered 21/4 Cr--1 Mo steel with different carbon contents were examined. The primary objective was the determination of the conditions that affect the correlation. The following relationships were obeyed: t/sub r/ = C/epsilon/sub s/ and t2 = F/sub s/t/sub r/, where t2 is the time to start tertiary creep, t/sub r/ is the rupture life, epsilon/sub s/ is the steady-state creep rate, and C and F/sub s/ are constants. The primary microstructural constituent (proeutectoid ferrite or bainite) of the matrix and the precipitates present in that matrix (before test or formed during test) played a significant role in the correlation of the data with the empirical relationships. (U.S.)

  11. TOXICOPHORES AND QUANTITATIVE STRUCTURE -TOXICITY RELATIONSHIPS FOR SOME ENVIRONMENTAL POLLUTANTS

    Directory of Open Access Journals (Sweden)

    N. N. Gorinchoy

    2008-06-01

    Full Text Available The electron-conformational (EC method is employed to reveal the toxicophore and to predict aquatic toxicity quantitatively using as a training set a series of 51 compounds that have aquatic toxicity to fish. By performing conformational analysis (optimization of geometries of the low-energy conformers by the PM3 method and electronic structure calculations (by ab initio method corrected within the SM54/PM3 solvatation model, the Electron-Conformational Matrix of Congruity (ECMC was constructed for each conformation of these compounds. The toxicophore defined as the EC sub-matrix of activity (ECSA, a sub-matrix with matrix elements common to all the active compounds under consideration within minimal tolerances, is determined by an iterative procedure of comparison of their ECMC’s, gradually minimizing the tolerances. Starting with only the four most toxic compounds, their ECSA (toxicophore was found to consists of a 4x4 matrix (four sites with certain electronic and topologic characteristics which was shown to be present in 17 most active compounds. A structure-toxicity correlation between three toxicophore parameters and the activities of these 17 compounds with R2=0.94 was found. It is shown that the same toxicophore with larger tolerances satisfies the compounds with les activity, thus explicitly demonstrating how the activity is controlled by the tolerances quantitatively and which atoms (sites are most flexible in this respect. This allows for getting slightly different toxicophores for different levels of activity. For some active compounds that have no toxicophore a bimolecular mechanism of activity is suggested. Distinguished from other QSAR methods, no arbitrary descriptors and no statistics are involved in this EC structure-activity investigation.

  12. 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

  13. Structure -- Magnetic Property Correlations in TiO 2 Nanotube Arrays

    Science.gov (United States)

    Mohammad Hosseinpour, Pegah

    TiO2 nanotube arrays are promising candidates for applications such as photocatalysis and for potential employment in spin-electronic (spintronic) devices. The functionality of TiO2-based nanotubes is highly dependent on their structure (microstructure and crystallographic symmetry) and magnetic properties. Unified understanding of the influence of these factors on the electronic structure of TiO2 is of paramount importance towards engineering these materials. This Dissertation aims at investigating the correlations of the morphology, crystallinity, crystal structure, electronic structure and magnetic properties of TiO2 nanotubes, with potential relevance to their functionality. Self-ordered arrays of amorphous TiO2 nanotubes (pure and Fe-doped with cationic concentration of ~2.1 at%) were synthesized by the electrochemical anodization technique, followed by subjecting them to thermal treatments up to 450 °C to crystallize these nanostructures. A variety of probes---morphological, structural, magnetic and spectroscopic---were used to characterize the properties of these nanostructures as functions of their processing conditions and the dopant content. Structure-functionality relationships in these nanostructures were verified by examining the photodegradation rate of methyl orange (a model water pollutant) in presence of TiO2 nanotubes under UV-Visible light irradiation. Results from this Dissertation research demonstrated that post-synthesis processing conditions---specifically, the nature of the annealing environment, as well as the presence of an external dopant, can alter the crystal structure and local electronic environment in TiO2 nanotubes, with subsequent effects on the magnetic properties of these nanostructures. The fundamental knowledge obtained in this research, on the interrelations of structural-magnetic properties and their potential influence on the functionality of TiO 2-based nanotubes, can be extended to the metal oxide semiconducting systems in general and is anticipated to provide avenues toward novel materials with enhanced functionality that originates from such tailored structural and magnetic characteristics. Despite the success achieved in this Dissertation, there are still open questions to be addressed in order to further enhance the fundamental knowledge of structure---magnetic property correlations in TiO2 nanotubes. In this regard, the concluding section of this Dissertation provides recommendations for additional experiments. Accomplishment of these recommendations is anticipated to provide enhanced insight into the various aspects of property-functionality relationships in TiO2-based nanomaterials, and provides paths to engineer novel multifunctional oxide-based materials for energy-related applications.

  14. On the mechanical properties of hierarchically structured biological materials

    OpenAIRE

    Bechtle, Sabine; Ang, Siang Fung; Schneider, Gerold A.; Keramische Hochleistungswerkstoffe M9

    2010-01-01

    Many biological materials are hierarchically structured which means that they are designed from the nano- to the macroscale in a sometimes self-similar way. There are lots of papers published including very detailed descriptions of these structures at all length scales ? however, investigations of mechanical properties are most often focused on either nano-indentation or bulk mechanical testing characterizing properties at the smallest or largest size scale. Interestingly, there are hardly an...

  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. Formation, structure and rheological properties of soy protein gels.

    OpenAIRE

    Renkema, J.M.S.

    2001-01-01

    Keywords: soy protein isolate, glycinin,?-conglycinin, heat denaturation, gelation, network structure, rheology, permeability measurements, microscopy, pH, ionic strength, emulsified oil dropletsThis study was performed to understand the factors determining heat-induced formation and properties of soy protein gels the relations between gel properties and network structure in order to support application of soy proteins in food products. Three soy protein preparations were used: soy protein is...

  17. Effect of heat treatment conditions on the structure and mechanical properties of DP-type steel

    Directory of Open Access Journals (Sweden)

    J. Adamczyk

    2006-04-01

    Full Text Available Purpose: The aim of the paper is to determine the influence of the initial structure and heat treatment conditions on mechanical properties of DP-type steel.Design/methodology/approach: The heat treatment of the low-carbon steel in order to obtain a DP-type structure of desirable ferrite and martensite fractions was realized. In order to investigate the structure light and transmission electron microscopy methods were used. Mechanical properties were determined by means of tensile test.Findings: It was found that a different initial structure influences essentially the martensite morphology in a final DP-type structure. It can occur as a network, fine fibres or islands in a ferritic matrix of high dislocation density in the vicinity of diffusionless transformation products of austenite. The best mechanical properties (UTS=800MPa, YS0.2=520MPa, TEl=20%, UEl=16% has a steel with the martensite in a form of fine fibres.Research limitations/implications: Continuation of the investigations in the field of using the thermomechanical processing to obtain a DP-type steel is foreseen.Practical implications: The established heat treatment conditions can be useful at manufacturing DP-type sheets of high strength and ductile properties and a good suitability for metalforming operations.Originality/value: The relationship between the initial structure and martensite morphology in DP-type steels was specified.

  18. 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

  19. New membrane structures with proton conducting properties

    DEFF Research Database (Denmark)

    Nørgaard, Casper Frydendal

    2009-01-01

    Perfluorosulfonic acid membranes (e.g. Nafion®) are the most widely applied electrolytes in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) because of their good chemical stability, mechanical properties and high proton conductivity, when well hydrated. The upper limit of operating temperature for these membranes is restricted by the loss of conductivity and dimensional stability as the temperature reaches the boiling point of water and the glass transition temperature of the polymer. At low re...

  20. 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

  1. Dentin Caries Zones: Mineral, Structure, and Properties

    OpenAIRE

    Pugach, M.K.; Strother, J.; Darling, C L; Fried, D; Gansky, S.A.; Marshall, S J; Marshall, G. W.

    2009-01-01

    Caries Detector staining reveals 4 zones in dentin containing caries lesions, but characteristics of each zone are not well-defined. We therefore investigated the physical and microstructural properties of carious dentin in the 4 different zones to determine important differences revealed by Caries Detector staining. Six arrested dentin caries lesions and 2 normal controls were Caries-Detector-stained, each zone (pink, light pink, transparent, apparently normal) being analyzed by atomic force...

  2. 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)

  3. 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.

  4. General Relationship between Field Electrical Resistivity Value (ERV and Basic Geotechnical Properties (BGP

    Directory of Open Access Journals (Sweden)

    Mohd Hazreek Zainal Abidin

    2014-03-01

    Full Text Available Normal 0 21 false false false MS X-NONE X-NONE MicrosoftInternetExplorer4 Electrical resistivity technique is a popular alternative method used in geotechnical soil investigations. Most past applications have been particularly in the area of subsurface ground investigations such as to locate boulder, bedrock, water table, etc. Traditionally, this method was performed by a geophysicist expert for data acquisition, processing and interpretation. The final outcome from the electrical resistivity technique was an anomaly image which used to describe and conclude the particular soil condition measured. The anomalies highlighted uncertainties on the nature of soil that was often variable and depended on each particular site condition that gave a site dependent soil electrical resistivity value (ERV. Hence, this study demonstrates a relationship between ERV (? and some of the basic geotechnical properties (BGP such as soil moisture content (w, grain size of geomaterial (CS or FS, density (?bulk and ?dry, porosity (?, void ratio (e and Atterberg limit (AL. Different soil samples were collected and tested under field and laboratory conditions to determine basic geotechnical properties immediately after the field electrical resistivity method was performed. It was found that the electrical resistivity value was different for number of soils tested and was relatively subjective to variations in the geotechnical properties. In other words, electrical resistivity value was greatly influenced by the geotechnical properties as the ERV was higher due to the lower moisture content, void ratio and porosity with a higher value of soil density and vice versa. The relationship of ERV and BGP can be described by ? ? 1/w, ? ? CS, ? ? 1/FS, ? ? ?bulk/dry and ? ? 1/AL. Hence, it was shown that behaviour of ERV was significantly influenced by the variation of basic soil properties and thus applicable to support and enhance the conventional stand alone anomaly outcome which is traditionally used for interpretation purposes.

  5. Relationship between Structural and Stress Relaxation in a Block-Copolymer Melt

    International Nuclear Information System (INIS)

    The relationship between structural relaxation on molecular length scales and macroscopic stress relaxation was explored in a disordered block-copolymer melt. Experiments show that the structural relaxation time, measured by x-ray photon correlation spectroscopy is larger than the terminal stress relaxation time, measured by rheology, by factors as large as 100. We demonstrate that the structural relaxation data are dominated by the diffusion of intact micelles while the stress relaxation data are dominated by contributions due to disordered concentration fluctuations

  6. Quantitative Structure – Antioxidant Activity Relationships of Flavonoid Compounds

    OpenAIRE

    Károly Héberger; Judit Jakus; Orsolya Farkas

    2004-01-01

    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....

  7. 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.

  8. Highlighting the Structure-Function Relationship of the Brain with the Ising Model and Graph Theory

    OpenAIRE

    Das, T. K.; P. M. Abeyasinghe; J.S. Crone; 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 fi...

  9. Inhibitors of bacterial and mammalian hyaluronidase - Synthesis and structure-activity relationships

    OpenAIRE

    Salmen, Sunnhild

    2004-01-01

    The role and the importance of hyaluronic acid and hyaluronidases in physiological and pathophysiological processes are largely misunderstood, so that selective and potent hyaluronidase inhibitors are required. As such compounds are not known so far, the goal of this project was to identify and to synthesise lead-like compounds, to optimise the structures and to study the structure-activity relationships. Therefore, we applied the following strategies: structurally dif...

  10. The relationship of character structure to persuasive communication in advertising.

    Science.gov (United States)

    Chatterjee, Anindya; Hunt, James M

    2005-02-01

    The persuasive effect of character structure--defined as a person's organized set of drives, dispositions, and satisfactions with which they approach the world--was assessed in the context of printed advertising. Subjects were exposed to one of two levels of argument strength (strong versus weak) and one of two levels of message spokesperson (celebrity versus noncelebrity) in a printed-advertising task. Subjects classified as Other-directed, individuals who possess a strong need to get along with others, exhibited greater attitudinal responsiveness to the test advertisement as measured on a composite attitude scale than did those classified as Inner-directed, needing to get ahead, or succeed. Other-directed subjects' attitude scores were more responsive to the message source than were the comparable scores of Inner-directed subjects. Results regarding argument strength were not significant but suggest that Other-directed attitudes are influenced by a combination of textual arguments and social cues. PMID:15825930

  11. Relationships between Visual Field Sensitivity and Spectral Absorption Properties of the Neuroretinal Rim in Glaucoma by Multispectral Imaging

    OpenAIRE

    Denniss, Jonathan; Schiessl, Ingo; Nourrit, Vincent; Fenerty, Cecilia H; Gautam, Ramesh; Henson, David B

    2011-01-01

    In this study, multispectral imaging was used to show relationships between spectral absorption properties of the neuroretinal rim and visual field loss in glaucoma. Multispectral imaging may provide clinically useful information for assessment of glaucoma.

  12. 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...

  13. 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...

  14. 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...

  15. Structure and evolution of online social relationships: Heterogeneity in warm discussions

    OpenAIRE

    Goh, K. -I.; Eom, Y. -H.; Jeong, H.; Kahng, B.; D.; Kim

    2006-01-01

    With the advancement in the information age, people are using electronic media more frequently for communications, and social relationships are also increasingly resorting to online channels. While extensive studies on traditional social networks have been carried out, little has been done on online social network. Here we analyze the structure and evolution of online social relationships by examining the temporal records of a bulletin board system (BBS) in a university. The...

  16. Body mass index, perceived health, and happiness: their determinants and structural relationships

    OpenAIRE

    Cornelisse-Vermaat, J.R.; Antonides, G.; Ophem, J.A.C.; Maassen van 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 ...

  17. Vibrational Properties Study on Canter Fractal Structure

    Science.gov (United States)

    Zhang, Haifeng; Tang, Tao; Xu, Wenlan; Li, Yongping

    1995-02-01

    A new system of Canter fractal models was created and studied, the density of states (DOS) as well as wavefunctions of the phonon in this kind of structure were calculated and discussed, in which it shows a new kind of branch rules for the DOS and new characteristics for the wavefunctions.

  18. Novel antineoplastic platinum(IV) complexes: synthesis, characterization, biological investigations and structure-activity relationships

    International Nuclear Information System (INIS)

    Platinum(II) complexes represent one of the most widely used classes of cytostatics in anticancer chemotherapy. Their clinical effectiveness is accompanied by severe doselimiting side effects, intrinsic and/or acquired tumor resistance and the inconvenient and cost intensive way of intravenous administration. Platinum(IV) complexes also possess antitumor activity and their physicochemical and chemical properties could be utilized in order to overcome the main drawbacks of platinum(II)-based drugs. The successful design of platinum(IV) chemotherapeutics requires a careful examination of their pharmacology and toxicology, the formulation of structure-activity relationships and the development of new synthetic approaches. Within this PhD work, novel bis-, tris- and tetrakis(carboxylato)platinum(IV) complexes, designed as prodrugs for cis-[Pt(EtNH2)2Cl2] (cisplatin analogue with higher lipophilicity), carboplatin and nedaplatin were synthesized. For this purpose, the respective platinum(II) complexes were oxidized with H2O2 in aqueous media and further carboxylated using different cyclic anhydrides (succinic, glutaric, 3-methylglutaric and 3,3-dimethylglutaric anhydride). The resulting compounds were subsequently derivatized by activation of their free carboxylic groups with CDI (1,1’-carbonyldiimidazol), followed by reaction with various amines or alcohols, yielding the desired amides and esters, respectively. All complexes were fully characterized, using multinuclear (1H, 13C, 15N and 195Pt) 1D and 2D NMR spectroscopy, elemental analysis, ESI-MS, ATR-FTIR, HPLC and exemplarily X-ray diffraction for some of the compounds. In vitro cytotoxicity of the novel complexes was examined in four human tumor cell lines originating from ovarian carcinoma (CH1 and SK-OV-3), colon carcinoma (SW480) and non-small cell lung cancer (A549) by means of the MTT colorimetrical assay. Comparative analysis of the lipophilicity, electrochemistry and rate of reduction by ascorbic acid of the new complexes was conducted in order to better understand their pharmacological behavior. Finally, computational studies with respect to the electronic structure and redox properties of the investigated compounds, using DFT methods were performed. Furthermore, QSAR models with good explanatory and predictive properties for the cytotoxicity in the cisplatin sensitive cell line CH1 and the intrinsically cisplatin resistant cell line SW480 were developed. (author)

  19. Structure-biological Activity Relationship of Analogues of 2-Chlorobenzylidenemalononitrile -A Riot-control Agent

    Directory of Open Access Journals (Sweden)

    P. K. Gutch

    2005-10-01

    Full Text Available The riot-control agent 2-chlorobenzylidenemalononitrile (CS and its ortho-and parasubstituted benzylidenemalononitrile (BMN analogues were synthesised and characterised by spectroscopic techniques (IR, NMR, and mass spectrometry and microanalysis, and their structure-biological activity relationship studies were carried out to know the factors responsible for sensory irritation. Hydrophobicity of substituted BMNs were determined by high-performance liquid chromatography (HPLC, which is an important determinant of the irritancy. The vapour pressure of a compound is a physico-chemical property important for the assessment of its fate in the environment. The vapour pressures of BMNs were determined by static method by an isoteniscope. A systematic investigation of sensory irritation was carried out by evaluating decrease in respiratory rate (RDs, in mice. The R.Dsi as biological parameter was correlated with physical parameters such as hydrophobicity, vapour pressure, size of molecules, and chemical reactivity of its BMNs with dimethylaminoethyl mercaptans (DEAEMs as a simulant of protein-SH group. A biosignifkant correlation (0.75-0.80 was obtained.by correlating all the above parameters using multiple linear regression equation.

  20. Quantum nanosystems structure, properties, and interactions

    CERN Document Server

    Putz, Mihai V

    2015-01-01

    The need for economically feasible and multifunctional materials becomes more acute as the natural physical and chemical resources reveal either their limits or reveal the difficulties and increasing costs in storage, transport, and conversion. This reference presents the work from contributors from various fields, of various ages and from different countries, creating a valuable collection of research that will advance the fundamental and innovative techniques of nanosystems and their interactions. The authors cover self-assembly, self-regenerating, storage, and directional properties of inte