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Sample records for structure properties relationships

  1. Structure Property Relationships of Carboxylic Acid Isosteres.

    Science.gov (United States)

    Lassalas, Pierrik; Gay, Bryant; Lasfargeas, Caroline; James, Michael J; Tran, Van; Vijayendran, Krishna G; Brunden, Kurt R; Kozlowski, Marisa C; Thomas, Craig J; Smith, Amos B; Huryn, Donna M; Ballatore, Carlo

    2016-04-14

    The replacement of a carboxylic acid with a surrogate structure, or (bio)-isostere, is a classical strategy in medicinal chemistry. The general underlying principle is that by maintaining the features of the carboxylic acid critical for biological activity, but appropriately modifying the physicochemical properties, improved analogs may result. In this context, a systematic assessment of the physicochemical properties of carboxylic acid isosteres would be desirable to enable more informed decisions of potential replacements to be used for analog design. Herein we report the structure-property relationships (SPR) of 35 phenylpropionic acid derivatives, in which the carboxylic acid moiety is replaced with a series of known isosteres. The data set generated provides an assessment of the relative impact on the physicochemical properties that these replacements may have compared to the carboxylic acid analog. As such, this study presents a framework for how to rationally apply isosteric replacements of the carboxylic acid functional group.

  2. Structure Property Relationships of Biobased Epoxy Resins

    Science.gov (United States)

    Maiorana, Anthony Surraht

    The thesis is about the synthesis, characterization, development, and application of epoxy resins derived from sustainable feedstocks such as lingo-cellulose, plant oils, and other non-food feedstocks. The thesis can be divided into two main topics 1) the synthesis and structure property relationship investigation of new biobased epoxy resin families and 2) mixing epoxy resins with reactive diluents, nanoparticles, toughening agents, and understanding co-curing reactions, filler/matrix interactions, and cured epoxy resin thermomechanical, viscoelastic, and dielectric properties. The thesis seeks to bridge the gap between new epoxy resin development, application for composites and advanced materials, processing and manufacturing, and end of life of thermoset polymers. The structures of uncured epoxy resins are characterized through traditional small molecule techniques such as nuclear magnetic resonance, high resolution mass spectrometry, and infrared spectroscopy. The structure of epoxy resin monomers are further understood through the process of curing the resins and cured resins' properties through rheology, chemorheology, dynamic mechanical analysis, tensile testing, fracture toughness, differential scanning calorimetry, scanning electron microscopy, thermogravimetric analysis, and notched izod impact testing. It was found that diphenolate esters are viable alternatives to bisphenol A and that the structure of the ester side chain can have signifi-cant effects on monomer viscosity. The structure of the cured diphenolate based epoxy resins also influence glass transition temperature and dielectric properties. Incorporation of reactive diluents and flexible resins can lower viscosity, extend gel time, and enable processing of high filler content composites and increase fracture toughness. Incorpora-tion of high elastic modulus nanoparticles such as graphene can provide increases in physical properties such as elastic modulus and fracture toughness. The synthesis

  3. Structure-Property Relationship of Thermoset Nanocomposites

    NARCIS (Netherlands)

    Faraz, M.I.

    2013-01-01

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

  4. Structure property relationships in various filled polymers

    Science.gov (United States)

    Yu, Jiong

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

  5. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

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

    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...

  6. Quantitative Structure-Property Relationship Research of Main Group Compounds

    Institute of Scientific and Technical Information of China (English)

    LEI Kelin; WANG Zhendong

    2006-01-01

    New approaches were applied to improve the molecular connectivity indices mχv. The vertex valence is redefined and it was reasonable for hydrogen atom. The distances between vertices were used to propose novel connectivity topological indexes. The vertices and the distances in a molecular graph were taken into account in this definition. The linear regression was used to develop the structural property models. The results indicate that the novel connectivity topological indexes are useful model parameters for Quantitative Structure-Property Relationship(QSPR) analysis.

  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. Structure-Property Relationships of Solids in Pharmaceutical Processing

    Science.gov (United States)

    Chattoraj, Sayantan

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

  9. Bio-related noble metal nanoparticle structure property relationships

    Science.gov (United States)

    Leonard, Donovan Nicholas

    Structure property relationships of noble metal nanoparticles (NPs) can be drastically different than bulk properties of the same metals. This research study used state-of-the-art analytical electron microscopy and scanned probe microscopy to determine material properties on the nanoscale of bio-related Au and Pd NPs. Recently, it has been demonstrated the self-assembly of Au NPs on functionalized silica surfaces creates a conductive surface. Determination of the aggregate morphology responsible for electron conduction was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, changes in the electrical properties of the substrates after low temperature (encapsulate Au NPs. Results indicated the sol-gel deposited SiO2 had a band gap energy of ˜8.9eV, bulk plasmon-peak energy of ˜25.5eV and chemical composition of stoichiometric SiO2. Lastly, an attempt to elicit structure property relationships of novel RNA mediated Pd hexagon NPs was performed. Selected area electron diffraction (SAD), low voltage scanning transmission electron microscopy (LV-STEM), electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) were chosen for characterization of atomic ordering, chemical composition and optoelectronic properties of the novel nanostructures. Data from control experiments found the hexagons could be made without RNA and confirmed the presence of nanocrystalline Pd metal NPs in unpurified Pd2(DBA)3 reagent powder. Furthermore, the study determined the hexagon platelets to have a chemical composition of ˜90at% carbon and ˜10at% Pd and a lattice parameter corresponding to molecular crystals of Pd2(DBA)3 precursor, not Pd metal.* *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Windows MediaPlayer or RealPlayer.

  10. Food structure: Its formation and relationships with other properties.

    Science.gov (United States)

    Joardder, Mohammad U H; Kumar, Chandan; Karim, M A

    2017-04-13

    Food materials are complex in nature as it has heterogeneous, amorphous, hygroscopic and porous properties. During processing, microstructure of food materials changes which significantly affects other properties of food. An appropriate understanding of the microstructure of the raw food material and its evolution during processing is critical in order to understand and accurately describe dehydration processes and quality anticipation. This review critically assesses the factors that influence the modification of microstructure in the course of drying of fruits and vegetables. The effect of simultaneous heat and mass transfer on microstructure in various drying methods is investigated. Effects of changes in microstructure on other functional properties of dried foods are discussed. After an extensive review of the literature, it is found that development of food structure significantly depends on fresh food properties and process parameters. Also, modification of microstructure influences the other properties of final product. An enhanced understanding of the relationships between food microstructure, drying process parameters and final product quality will facilitate the energy efficient optimum design of the food processor in order to achieve high-quality food.

  11. Oxide Thermoelectric Materials: A Structure-Property Relationship

    Science.gov (United States)

    Nag, Abanti; Shubha, V.

    2014-04-01

    Recent demand for thermoelectric materials for power harvesting from automobile and industrial waste heat requires oxide materials because of their potential advantages over intermetallic alloys in terms of chemical and thermal stability at high temperatures. Achievement of thermoelectric figure of merit equivalent to unity ( ZT ≈ 1) for transition-metal oxides necessitates a second look at the fundamental theory on the basis of the structure-property relationship giving rise to electron correlation accompanied by spin fluctuation. Promising transition-metal oxides based on wide-bandgap semiconductors, perovskite and layered oxides have been studied as potential candidate n- and p-type materials. This paper reviews the correlation between the crystal structure and thermoelectric properties of transition-metal oxides. The crystal-site-dependent electronic configuration and spin degeneracy to control the thermopower and electron-phonon interaction leading to polaron hopping to control electrical conductivity is discussed. Crystal structure tailoring leading to phonon scattering at interfaces and nanograin domains to achieve low thermal conductivity is also highlighted.

  12. 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

  13. Relationship Between Structure and Viscoelastic Properties of Geosynthetics

    Directory of Open Access Journals (Sweden)

    Loginova Irina

    2016-01-01

    Full Text Available In this work, a study on viscoelastic properties of geosynthetic materials used in civil engineering is presented. Six samples of geofabrics and geogrids with different structures including woven geotextile fabric, nonwoven geotextile fabrics, warp-knitted geogrids and extruded geogrid were investigated. The tensile properties of geosynthetics including tensile strength, strain at maximum load and tensile load at specified strain have been determined. The creep and relaxation tests were carried out. The structure type was found to significantly affect the viscoelastic properties of the geosynthetics materials. In the article some results of numerous conducted tests are presented, analyzed and may be used to preselection of geosynthetics materials.

  14. 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

  15. 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.

  16. Structure-property relationships in graphene/polymer nanocomposites

    Science.gov (United States)

    Iqbal, Muhammad Z.

    Graphene's unique combination of excellent electrical, thermal, and mechanical properties can provide multi-functional reinforcement for polymer nanocomposites. However, poor dispersion of graphene in non-polar polyolefins limits its applications as a universal filler. Thus, the overall goal of this thesis was to improve graphene's dispersion in graphene/polyolefin nanocomposites and develop processing-structure-property relationships. A new polymer matrix was synthesized by blending polyethylene (PE) with oxidized polyethylene (OPE). Inclusion of OPE in PE produced miscible blends, but the miscibility decreased with increasing OPE loading. Meanwhile, the Young's modulus of blends increased with increasing OPE concentration, attributed to decreased long period order in PE and increased crystallinity. In addition, the miscibility of OPE in PE substantially reduced the viscosity of blends. Using thermally reduced graphene (TRG) produced by simultaneous thermal exfoliation and reduction of graphite oxide, electrically conductive nanocomposites were manufactured by incorporating TRG in PE/OPE blends via solution blending. The rheological and electrical percolations decreased substantially to 0.3 and 0.13 vol% of TRG in PE/OPE/TRG nanocomposites compared to 1.0 and 0.3 vol% in PE/TRG nanocomposites. Improved dispersion of TRG in blends was attributed to increased TRG/polymer interactions, leading to high aspect ratio of the dispersed TRG. A universal Brownian dispersion mechanism for graphene was concluded similar to that of carbon nanotubes, following the Doi-Edwards theory. Furthermore, the improved dispersion of TRG correlated with the formation of surface fractals in PE/OPE/TRG nanocomposites, whereas the poor dispersion of TRG in PE led to the formation of only mass fractals. Moreover, graphene and carbon black (CB) were combined as a synergic filler for manufacturing electrically conductive PE nanocomposites. Smaller fractals were observed at lower CB

  17. 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.

  18. Relationship between molecular structure and tribological properties of phosphazene lubricants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Cyclotriphosphazene lubricants were synthesized and the relationship between theirstructures and tribological properties was investigated using an Optimol SRV oscillating frictionand wear tester and one-way reciprocating friction tester. It was found that aryloxyphosphazenewith polar substituent as a lubricant of steel/steel and steel/aluminum pair gave low wear, whilearyloxyphosphazene with nonpolar group on the phenyl pendant led to high wear. Phosphazeneprovides poor lubricity for steel/aluminum system under low load (0.5-3 N). The XPS analyticalresults of the antiwear films generated on the steel and aluminum surface indicate that phos-phazene reacted with steel or aluminum counterface and formed a surface protecting film consist-ing of fluoride and organic compounds containing O, C, F, N, P during friction. This contributes tcreduce the friction and wear of steel/aluminum system.

  19. 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.

  20. Structure-property relationships in silica-siloxane nanocomposite materials

    Energy Technology Data Exchange (ETDEWEB)

    Ulibarri, T.A.; Derzon, D.K.; Wang, L.C.

    1997-03-01

    The simultaneous formation of a filler phase and a polymer matrix via in situ sol-gel techniques provides silica-siloxane nanocomposite materials of high strength. This study concentrates on the effects of temperature and relative humidity on a trimodal polymer system in an attempt to accelerate the reaction as well as evaluate subtle process- structure-property relations. It was found that successful process acceleration is only viable for high humidity systems when using the tin(IV) catalyst dibutyltin dilaurate. Processes involving low humidity were found to be very temperature and time dependent. Bimodal systems were investigated and demonstrated that the presence of a short-chain component led to enhanced material strength. This part of the study also revealed a link between the particle size and population density and the optimization of material properties.

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

    Science.gov (United States)

    Solanki, Archana; Mehta, Jayen; Thakore, Sonal

    2014-09-22

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

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

    Directory of Open Access Journals (Sweden)

    Douglas J. Kleinc

    2006-09-01

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

  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. Relationships between the Processing Parameters of Melt Blown Nonwoven Fabric and Its Structure and Filtration Property

    Institute of Scientific and Technical Information of China (English)

    潘莺; 王善元

    2001-01-01

    Based on the processing experiment and sodium flame test this paper deals with the relationship between processing parameters, structure, and filtration property of melt blown fabric. Through the image analysis of Questar micro-images in combination with the SEM observation and the measurement of some macrostructure indices, the relationship between the processing parameters and the structure especially the microstructure is emphasized Finally the effect of somestructure factors on filtration properties is discussed theoretically.

  5. Structure-property relationships of flexible polyurethane foams

    Science.gov (United States)

    Aneja, Ashish

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

  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. Processing-structure-properties relationships in PLA nanocomposite films

    Science.gov (United States)

    Di Maio, L.; Scarfato, P.; Garofalo, E.; Galdi, M. R.; D'Arienzo, L.; Incarnato, L.

    2014-05-01

    This work deals on the possibility to improve performances of PLA-based nanocomposite films, for packaging applications, through conveniently tuning materials and processing conditions in melt compounding technology. In particular, two types of polylactic acid and different types of filler selected from montmorillonites and bentonites families were used to prepare the hybrid systems by using a twin-screw extruder. The effect of biaxial drawing on morphology and properties of the nanocomposites, produced by film blowing, was investigated.

  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. Analysis of the relationship between the structure and aromatic properties of chemical compounds.

    Science.gov (United States)

    Debska, Barbara; Guzowska-Swider, Barbara

    2003-04-01

    This paper presents the results of research on the relationship between the structure and odour properties of a selection of chemical compounds. The research concerns five groups of esters, each with a different smell: almond, apricot, apple, pineapple and rose. The supposed relationship between the smell and certain selected attributes of each molecule was examined by various pattern recognition techniques using programs developed in the Department of Computer Chemistry at Rzeszów University of Technology.

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

    Science.gov (United States)

    Ivanova, Bojidarka B.; Spiteller, Michael

    2012-09-01

    A comprehensive screening of fifteen functionalized Ergot-alkaloids, containing bulk aliphatic cyclic substituents at D-ring of the ergoline molecular skeleton was performed, studying their structure-active relationships and model interactions with α2A-adreno-, serotonin (5HT2A) and dopamine D3 (D3A) receptors. The accounted high affinity to the receptors binding loops and unusual bonding situations, joined with the molecular flexibility of the substituents and the presence of proton accepting/donating functional groups in the studied alkaloids, may contribute to further understanding the mechanisms of biological activity in vivo and in predicting their therapeutic potential in central nervous system (CNS), including those related the Schizophrenia. Since the presented correlation between the molecular structure and properties, was based on the comprehensively theoretical computational and experimental physical study on the successfully isolated derivatives, through using routine synthetic pathways in a relatively high yields, marked these derivatives as 'treasure' for further experimental and theoretical studied in areas such as: (a) pharmacological and clinical testing; (b) molecular-drugs design of novel psychoactive substances; (c) development of the analytical protocols for determination of Ergot-alkaloids through a functionalization of the ergoline-skeleton, and more.

  11. Structure-spectroscopic property relationships in a series of platinum acetylides

    Science.gov (United States)

    Cooper, Thomas M.; Haley, Joy E.; Krein, Douglas M.; Burke, Aaron R.; Slagle, Jonathan E.

    2016-09-01

    In order to understand electronic and conformational effects on structure-spectroscopic property relationships in platinum acetylides, we synthesized a model series of chromophores trans-Pt(PBu3)2(C-CPhenyl-X)2, where X = NH2, OCH3, diphenylamino, t-Bu, methyl, H, F, benzothiazole, trifluoromethyl, CN and nitro. We collected linear spectra, including ground state absorption, phosphorescence and phosphorescence excitation spectra. We also performed DFT and TDDFT calculations on the ground and excited state properties of these compounds. The calculations and experimental data show the excited state properties are a function of the electronic properties of the substituents and the molecular conformation.

  12. Mechanical Properties of Living Adherent Cells :Relationship with Structure and Function

    Institute of Scientific and Technical Information of China (English)

    R.; FODIL; S.; Féréol; E.; PLANUS; V.M.; LAURENT; B.; LOUIS; D.; ISABEY

    2005-01-01

    1 IntroductionMechanical properties of living cells are dependent on a variety of intracellular and/or extracellular factors (e.g., spatial organization of cytoskeleton (CSK) elements; internal tension; actomyosin contraction; contribution of proximal and/or more distal environment...). Because these factors are involved in biological processes as important as cell adhesion, locomotion, cell contraction, signalization, understanding the relationships between cell mechanical properties, structure and functio...

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

    Energy Technology Data Exchange (ETDEWEB)

    Han, M. K. [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    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 LaFe13-xSix 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 Re2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: 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 Tb3Zn3.6Al7.4: Partially ordered structure of Tb3Zn3.6Al7.4 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 Zn39(CrxAl1-x)81

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

    Energy Technology Data Exchange (ETDEWEB)

    Han, Mi-Kyung [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    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 LaFe13-xSix 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 NaZn13-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 RE2-xFe4Si14-y and proposed superstructure: This compound offers complex structural challenges such as fractional occupancies and their ordering in superstructure. (3) Electronic structure calculation of FeSi2: 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 Tb3Zn3.6Al7.4: Partially ordered structure of Tb3.6Zn13-xAl7.4 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 Zn39(CrxAl1-x

  15. 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.

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

    Science.gov (United States)

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

    2014-01-30

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

  17. Modelling Structure-Property Relationship for Copolymers by Structured Representation of Repeating Units

    Science.gov (United States)

    Bertinetto, Carlo; Duce, Celia; Micheli, Alessio; Starita, Antonina; Solaro, Roberto; Tiné, Maria R.

    2009-08-01

    We report here a recent study on the prediction by recursive neural network of the glass transition temperature of (meth)acrylic copolymers, for which appropriate structured representations are proposed. It is shown that the flexibility of such description allows for simultaneously treating different classes of compounds as well as accounting for different average properties such as tacticity and molar composition.

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

    Science.gov (United States)

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

    2014-12-16

    CONSPECTUS: Polydopamine (PDA), a black insoluble biopolymer produced by autoxidation of the catecholamine neurotransmitter dopamine (DA), and synthetic eumelanin polymers modeled to the black functional pigments of human skin, hair, and eyes have burst into the scene of materials science as versatile bioinspired functional systems for a very broad range of applications. PDA is characterized by extraordinary adhesion properties providing efficient and universal surface coating for diverse settings that include drug delivery, microfluidic systems, and water-treatment devices. Synthetic eumelanins from dopa or 5,6-dihydroxyindoles are the focus of increasing interest as UV-absorbing agents, antioxidants, free radical scavengers, and water-dependent hybrid electronic-ionic semiconductors. Because of their peculiar physicochemical properties, eumelanins and PDA hold considerable promise in nanomedicine and bioelectronics, as they are biocompatible, biodegradable, and exhibit suitable mechanical properties for integration with biological tissues. Despite considerable similarities, very few attempts have so far been made to provide an integrated unifying perspective of these two fields of technology-oriented chemical research, and progress toward application has been based more on empirical approaches than on a solid conceptual framework of structure-property relationships. The present Account is an attempt to fill this gap. Following a vis-à-vis of PDA and eumelanin chemistries, it provides an overall view of the various levels of chemical disorder in both systems and draws simple correlations with physicochemical properties based on experimental and computational approaches. The potential of large-scale simulations to capture the macroproperties of eumelanin-like materials and their hierarchical structures, to predict the physicochemical properties of new melanin-inspired materials, to understand the structure-property-function relationships of these materials from

  19. 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.

  20. 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

    2015-10-21

    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.

  1. 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.

  2. Quantitative Structure-Property Relationship on Prediction of Surface Tension of Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A quantitative structure-property relationship (QSPR) study has been made for the prediction of the surface tension of nonionic surfactants in aqueous solution.The regressed model includes a topological descriptor,the Kier & Hall index of zero order (KH0) of the hydrophobic segment of surfactant and a quantum chemical one,the heat of formation () of surfactant molecules.The established general QSPR between the surface tension and the descriptors produces a correlation coefficient of multiple determination,=0.9877,for 30 studied nonionic surfactants.

  3. Synthesis and quantitative structure-property relationships of side chain-modified hyodeoxycholic acid derivatives.

    Science.gov (United States)

    Sabbatini, Paola; Filipponi, Paolo; Sardella, Roccaldo; Natalini, Benedetto; Nuti, Roberto; Macchiarulo, Antonio; Pellicciari, Roberto; Gioiello, Antimo

    2013-08-30

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

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

    Directory of Open Access Journals (Sweden)

    Antimo Gioiello

    2013-08-01

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

  5. 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

  6. Quantitative structure property relationships for the adsorption of pharmaceuticals onto activated carbon.

    Science.gov (United States)

    Dickenson, E R V; Drewes, J E

    2010-01-01

    Isotherms were determined for the adsorption of five pharmaceutical residues, primidone, carbamazepine, ibuprofen, naproxen and diclofenac, to Calgon Filtrasorb 300 powdered activated carbon (PAC). The sorption behavior was examined in ultra-pure and wastewater effluent organic matter (EfOM) matrices, where more sorption was observed in the ultra-pure water for PAC doses greater than 10 mg/L suggesting the presence of EfOM hinders the sorption of the pharmaceuticals to the PAC. Adsorption behaviors were described by the Freundlich isotherm model. Quantitative structure property relationships (QSPRs) in the form of polyparameter linear solvation energy relationships were developed for simulating the Freundlich adsorption capacity in both ultra-pure and EfOM matrices. The significant 3D-based descriptors for the QSPRs were the molar volume, polarizability and hydrogen-bond donor parameters.

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

    Science.gov (United States)

    Hu, Fengshuo

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

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

    Science.gov (United States)

    Geise, Geoffrey

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

  9. Structural similarity based kriging for quantitative structure activity and property relationship modeling.

    Science.gov (United States)

    Teixeira, Ana L; Falcao, Andre O

    2014-07-28

    Structurally similar molecules tend to have similar properties, i.e. closer molecules in the molecular space are more likely to yield similar property values while distant molecules are more likely to yield different values. Based on this principle, we propose the use of a new method that takes into account the high dimensionality of the molecular space, predicting chemical, physical, or biological properties based on the most similar compounds with measured properties. This methodology uses ordinary kriging coupled with three different molecular similarity approaches (based on molecular descriptors, fingerprints, and atom matching) which creates an interpolation map over the molecular space that is capable of predicting properties/activities for diverse chemical data sets. The proposed method was tested in two data sets of diverse chemical compounds collected from the literature and preprocessed. One of the data sets contained dihydrofolate reductase inhibition activity data, and the second molecules for which aqueous solubility was known. The overall predictive results using kriging for both data sets comply with the results obtained in the literature using typical QSPR/QSAR approaches. However, the procedure did not involve any type of descriptor selection or even minimal information about each problem, suggesting that this approach is directly applicable to a large spectrum of problems in QSAR/QSPR. Furthermore, the predictive results improve significantly with the similarity threshold between the training and testing compounds, allowing the definition of a confidence threshold of similarity and error estimation for each case inferred. The use of kriging for interpolation over the molecular metric space is independent of the training data set size, and no reparametrizations are necessary when more compounds are added or removed from the set, and increasing the size of the database will consequentially improve the quality of the estimations. Finally it is shown

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

    Directory of Open Access Journals (Sweden)

    Grant Dubois

    2012-04-01

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

  11. Synthetic study on the relationship between structure and sweet taste properties of steviol glycosides.

    Science.gov (United States)

    Upreti, Mani; Dubois, Grant; Prakash, Indra

    2012-04-05

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

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

    Science.gov (United States)

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

    2016-11-07

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

    Irwin, Matthew Tyler

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

  15. Application of quantitative structure-property relationship analysis to estimate the vapor pressure of pesticides.

    Science.gov (United States)

    Goodarzi, Mohammad; Coelho, Leandro dos Santos; Honarparvar, Bahareh; Ortiz, Erlinda V; Duchowicz, Pablo R

    2016-06-01

    The application of molecular descriptors in describing Quantitative Structure Property Relationships (QSPR) for the estimation of vapor pressure (VP) of pesticides is of ongoing interest. In this study, QSPR models were developed using multiple linear regression (MLR) methods to predict the vapor pressure values of 162 pesticides. Several feature selection methods, namely the replacement method (RM), genetic algorithms (GA), stepwise regression (SR) and forward selection (FS), were used to select the most relevant molecular descriptors from a pool of variables. The optimum subset of molecular descriptors was used to build a QSPR model to estimate the vapor pressures of the selected pesticides. The Replacement Method improved the predictive ability of vapor pressures and was more reliable for the feature selection of these selected pesticides. The results provided satisfactory MLR models that had a satisfactory predictive ability, and will be important for predicting vapor pressure values for compounds with unknown values. This study may open new opportunities for designing and developing new pesticide.

  16. 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.

  17. Predicting total organic halide formation from drinking water chlorination using quantitative structure-property relationships.

    Science.gov (United States)

    Luilo, G B; Cabaniss, S E

    2011-10-01

    Chlorinating water which contains dissolved organic matter (DOM) produces disinfection byproducts, the majority of unknown structure. Hence, the total organic halide (TOX) measurement is used as a surrogate for toxic disinfection byproducts. This work derives a robust quantitative structure-property relationship (QSPR) for predicting the TOX formation potential of model compounds. Literature data for 49 compounds were used to train the QSPR in moles of chlorine per mole of compound (Cp) (mol-Cl/mol-Cp). The resulting QSPR has four descriptors, calibration [Formula: see text] of 0.72 and standard deviation of estimation of 0.43 mol-Cl/mol-Cp. Internal and external validation indicate that the QSPR has good predictive power and low bias (‰<‰1%). Applying this QSPR to predict TOX formation by DOM surrogates - tannic acid, two model fulvic acids and two agent-based model assemblages - gave a predicted TOX range of 136-184 µg-Cl/mg-C, consistent with experimental data for DOM, which ranged from 78 to 192 µg-Cl/mg-C. However, the limited structural variation in the training data may limit QSPR applicability; studies of more sulfur-containing compounds, heterocyclic compounds and high molecular weight compounds could lead to a more widely applicable QSPR.

  18. Dithiafulvenyl-substituted phenylacetylene derivatives: synthesis and structure-property-reactivity relationships.

    Science.gov (United States)

    Wang, Yunfei; Zhao, Yuming

    2015-10-07

    A series of regioisomers for dithiafulvenyl-substituted phenylacetylene derivatives was synthesized and characterized to show structure-dependent electronic properties and different reactivities in their oxidized states.

  19. Electronic Structure and Physical-Chemistry Property Relationship for Oxazole Derivatives by Ab Initio and DFT Methods

    OpenAIRE

    2011-01-01

    The geometric, electronic structure, effect of the substitution, and structure physical-chemistry relationship for oxazoles derivatives have been studied by ab initio and DFT theory. In the present work, the calculated values, namely, net charges, bond lengths, dipole moments, electron affinities, heats of formation, and QSAR properties are reported and discussed in terms of the reactivity of oxazole derivatives.

  20. The Structure-property Relationships of D-π-A BODIPY Dyes for Dye-sensitized Solar Cells.

    Science.gov (United States)

    Mao, Mao; Song, Qin-Hua

    2016-04-01

    BODIPY dyes have attracted considerable attention as potential photosensitizers in dye-sensitized solar cells (DSSCs) owing to their excellent optical properties and facile structural modification. This account focuses on recent advances in the molecular design of D-π-A BODIPY dyes for applications in DSSCs. Special attention has been paid to the structure-property relationships of D-π-A BODIPY dyes for DSSCs. The developmental process in the modified position at the BODIPY core with a donor/acceptor is described. The devices based on 2,6-modified BODIPY dyes exhibit better photovoltaic performance over other modified BODIPY dyes. Meanwhile, the research reveals the correlation of molecular structures (various donor chromophores, extended units, molecular frameworks, and long alkyl groups) with their photophysical and electrochemical properties and relates it to their performance in DSSCs. The structure-property relationships give valuable information and guidelines for designing new D-π-A BODIPY dyes for DSSCs.

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

    Science.gov (United States)

    Vilayurganapathy, Subramanian

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

  2. Design, synthesis, and structure-property relationships of isoindigo-based conjugated polymers.

    Science.gov (United States)

    Lei, Ting; Wang, Jie-Yu; Pei, Jian

    2014-04-15

    Conjugated polymers have developed rapidly due to their promising applications in low-cost, lightweight, and flexible electronics. The development of the third-generation donor-acceptor (D-A) polymers greatly improved the device performance in organic solar cells (OSCs) and field-effect transistors (FETs). However, for further improvement of device performance, scientists need to develop new building blocks, in particular electron-deficient aromatics, and gain an in-depth understanding of the structure-property relationships. Recently, isoindigo has been used as a new acceptor of D-A conjugated polymers. An isomer of indigo, isoindigo is a less well-known dye and can be isolated as a by-product from certain biological processes. It has two lactam rings and exhibits strong electron-withdrawing character. This electron deficiency gives isoindigo-based polymers intriguing properties, such as broad absorption and high open circuit voltage in OSCs, as well as high mobility and good ambient stability in FETs. In this Account, we review our recent progress on the design, synthesis, and structure-property relationship study of isoindigo-based polymers for FETs. Starting with some discussion on carrier transport in polymer films, we provide some basic strategies towards high-performance polymer FETs. We discuss the stability issue of devices, the impediment of the alkyl side chains, and the choice of the donor part of conjugated polymers. We demonstrate that introducing the isoindigo core effectively lowers the HOMO levels of polymers and provides FETs with long-time stability. In addition, we have found that when we use inappropriate alkyl side chains or non-centrosymmetric donors, the device performance of isoindigo polymers suffers. To further improve device performance and ambient stability, we propose several design strategies, such as using farther branched alkyl chains, modulating polymer energy levels, and extending π-conjugated backbones. We have found that using

  3. Understanding quantitative structure-property relationships uncertainty in environmental fate modeling.

    Science.gov (United States)

    Sarfraz Iqbal, M; Golsteijn, Laura; Öberg, Tomas; Sahlin, Ullrika; Papa, Ester; Kovarich, Simona; Huijbregts, Mark A J

    2013-04-01

    In cases in which experimental data on chemical-specific input parameters are lacking, chemical regulations allow the use of alternatives to testing, such as in silico predictions based on quantitative structure-property relationships (QSPRs). Such predictions are often given as point estimates; however, little is known about the extent to which uncertainties associated with QSPR predictions contribute to uncertainty in fate assessments. In the present study, QSPR-induced uncertainty in overall persistence (POV ) and long-range transport potential (LRTP) was studied by integrating QSPRs into probabilistic assessments of five polybrominated diphenyl ethers (PBDEs), using the multimedia fate model Simplebox. The uncertainty analysis considered QSPR predictions of the fate input parameters' melting point, water solubility, vapor pressure, organic carbon-water partition coefficient, hydroxyl radical degradation, biodegradation, and photolytic degradation. Uncertainty in POV and LRTP was dominated by the uncertainty in direct photolysis and the biodegradation half-life in water. However, the QSPRs developed specifically for PBDEs had a relatively low contribution to uncertainty. These findings suggest that the reliability of the ranking of PBDEs on the basis of POV and LRTP can be substantially improved by developing better QSPRs to estimate degradation properties. The present study demonstrates the use of uncertainty and sensitivity analyses in nontesting strategies and highlights the need for guidance when compounds fall outside the applicability domain of a QSPR.

  4. Interactions of Indole Derivatives with β-Cyclodextrin: A Quantitative Structure-Property Relationship Study.

    Directory of Open Access Journals (Sweden)

    Milan Šoškić

    Full Text Available Retention factors for 31 indole derivatives, most of them with auxin activity, were determined by high-performance liquid chromatography, using bonded β-cyclodextrin as a stationary phase. A three-parameter QSPR (quantitative structure-property relationship model, based on physico-chemical and structural descriptors was derived, which accounted for about 98% variations in the retention factors. The model suggests that the indole nucleus occupies the relatively apolar cavity of β-cyclodextrin while the carboxyl group of the indole -3-carboxylic acids makes hydrogen bonds with the hydroxyl groups of β-cyclodextrin. The length and flexibility of the side chain containing carboxyl group strongly affect the binding of these compounds to β-cyclodextrin. Non-acidic derivatives, unlike the indole-3-carboxylic acids, are poorly retained on the column. A reasonably well correlation was found between the retention factors of the indole-3-acetic acids and their relative binding affinities for human serum albumin, a carrier protein in the blood plasma. A less satisfactory correlation was obtained when the retention factors of the indole derivatives were compared with their affinities for auxin-binding protein 1, a plant auxin receptor.

  5. Interactions of Indole Derivatives with β-Cyclodextrin: A Quantitative Structure-Property Relationship Study.

    Science.gov (United States)

    Šoškić, Milan; Porobić, Ivana

    2016-01-01

    Retention factors for 31 indole derivatives, most of them with auxin activity, were determined by high-performance liquid chromatography, using bonded β-cyclodextrin as a stationary phase. A three-parameter QSPR (quantitative structure-property relationship) model, based on physico-chemical and structural descriptors was derived, which accounted for about 98% variations in the retention factors. The model suggests that the indole nucleus occupies the relatively apolar cavity of β-cyclodextrin while the carboxyl group of the indole -3-carboxylic acids makes hydrogen bonds with the hydroxyl groups of β-cyclodextrin. The length and flexibility of the side chain containing carboxyl group strongly affect the binding of these compounds to β-cyclodextrin. Non-acidic derivatives, unlike the indole-3-carboxylic acids, are poorly retained on the column. A reasonably well correlation was found between the retention factors of the indole-3-acetic acids and their relative binding affinities for human serum albumin, a carrier protein in the blood plasma. A less satisfactory correlation was obtained when the retention factors of the indole derivatives were compared with their affinities for auxin-binding protein 1, a plant auxin receptor.

  6. Interactions of Indole Derivatives with β-Cyclodextrin: A Quantitative Structure-Property Relationship Study

    Science.gov (United States)

    Šoškić, Milan; Porobić, Ivana

    2016-01-01

    Retention factors for 31 indole derivatives, most of them with auxin activity, were determined by high-performance liquid chromatography, using bonded β-cyclodextrin as a stationary phase. A three-parameter QSPR (quantitative structure-property relationship) model, based on physico-chemical and structural descriptors was derived, which accounted for about 98% variations in the retention factors. The model suggests that the indole nucleus occupies the relatively apolar cavity of β-cyclodextrin while the carboxyl group of the indole -3-carboxylic acids makes hydrogen bonds with the hydroxyl groups of β-cyclodextrin. The length and flexibility of the side chain containing carboxyl group strongly affect the binding of these compounds to β-cyclodextrin. Non-acidic derivatives, unlike the indole-3-carboxylic acids, are poorly retained on the column. A reasonably well correlation was found between the retention factors of the indole-3-acetic acids and their relative binding affinities for human serum albumin, a carrier protein in the blood plasma. A less satisfactory correlation was obtained when the retention factors of the indole derivatives were compared with their affinities for auxin-binding protein 1, a plant auxin receptor. PMID:27124734

  7. 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.

  8. Structure property relationships of nitride superlattice hard coatings prepared by pulsed laser deposition

    Science.gov (United States)

    Patel, Nitin

    Today, more than 40% of all cutting tools used in machining applications are covered with coatings. Coatings improve wear resistance, increase tool life, enable use at higher speed, and broaden the application range. Superlattices, where thin layers (typically deposited in an alternating fashion, are widely used commercially. Importantly, the hardness value of a superlattice (e.g. TiN/AlN) can significantly exceed the rule of mixture value. Superlattice coatings built from crystallographically dissimilar materials are not widely studied but hold promise for improvements in performance by allowing for both hardness and toughness to be simultaneously optimized. This is what this thesis is concerned with: a structure-property comparison of isostructural superlattices with corresponding non-isostructural superlattices. In order to grow both isostructural and non-isostructural superlattices from the same set of materials, it is necessary to grow monolithic films in different phases. Towards this end, the synthesis of different phases of AlN, (Ti,Al)N, TaN, and TiN was investigated. Films were grown by pulsed laser deposition in two different chambers that had different base pressures to study the effect of background gases on the phases and orientations of the films. Growth of AlN and (Ti,Al)N films is strongly affected in a chamber that had a base pressure of 10-6 Torr, but the films adopt their stable nitride structures in a chamber with the lower base pressure of 10-8 Torr. TaN adopts either the cubic rock salt structure or its stable hexagonal structure, depending on the growth temperature, while TiN grows as rock salt in all conditions. Single crystal epitaxial superlattices were then grown with different compositions, periodicities, and crystallographic orientations to compare the effect of chemistry, nanostructure, and crystallographic texture on hardness. Finally, the structure-property relationships of non-isostructural (cubic/hexagonal) superlattices are

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

    Directory of Open Access Journals (Sweden)

    Drago Skrtic

    2009-11-01

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

  10. Structure-Property Relationships in Atomic-Scale Junctions: Histograms and Beyond.

    Science.gov (United States)

    Hybertsen, Mark S; Venkataraman, Latha

    2016-03-15

    Over the past 10 years, there has been tremendous progress in the measurement, modeling and understanding of structure-function relationships in single molecule junctions. Numerous research groups have addressed significant scientific questions, directed both to conductance phenomena at the single molecule level and to the fundamental chemistry that controls junction functionality. Many different functionalities have been demonstrated, including single-molecule diodes, optically and mechanically activated switches, and, significantly, physical phenomena with no classical analogues, such as those based on quantum interference effects. Experimental techniques for reliable and reproducible single molecule junction formation and characterization have led to this progress. In particular, the scanning tunneling microscope based break-junction (STM-BJ) technique has enabled rapid, sequential measurement of large numbers of nanoscale junctions allowing a statistical analysis to readily distinguish reproducible characteristics. Harnessing fundamental link chemistry has provided the necessary chemical control over junction formation, enabling measurements that revealed clear relationships between molecular structure and conductance characteristics. Such link groups (amines, methylsuflides, pyridines, etc.) maintain a stable lone pair configuration that selectively bonds to specific, undercoordinated transition metal atoms available following rupture of a metal point contact in the STM-BJ experiments. This basic chemical principle rationalizes the observation of highly reproducible conductance signatures. Subsequently, the method has been extended to probe a variety of physical phenomena ranging from basic I-V characteristics to more complex properties such as thermopower and electrochemical response. By adapting the technique to a conducting cantilever atomic force microscope (AFM-BJ), simultaneous measurement of the mechanical characteristics of nanoscale junctions as they

  11. 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

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

    Science.gov (United States)

    Sheth, Agam R.

    This thesis strives to understand the structure-property relationships of some pharmaceutical crystals at the molecular level with emphasis on the effect of secondary processing on the solid phase. Using single crystal X-ray diffractometry (SCXRD), the structure of warfarin sodium 2-propanol adduct (W) was established to be a true solvate, contrary to previous reports. Using dynamic water vapor sorption, optical and environmental scanning electron microscopy, SCXRD, powder X-ray diffractometry (PXRD), volume computations and molecular modeling, the effect of relative humidity and temperature on the crystal structure of W was investigated. Ab initio calculations on piroxicam showed that the difference in energy between the two polymorphs, I and II, arises predominantly from the difference between their lattice energies. The detailed hydrogen bonding networks of the two polymorphs are described and compared using graph sets. Despite stabilization of the polymorphs by hydrogen bonds, pair-wise distribution function transforms show a loss of polymorphic memory upon cryogrinding the two polymorphs, leading to a difference in recrystallization behavior between amorphous piroxicam prepared from polymorphs I and II. Structural and solid-state changes of piroxicam polymorphs under mechanical stress were investigated using cryogenic grinding, PXRD, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, and diffuse-reflectance solid-state Fourier-transform infrared spectroscopy. Intermolecular proton transfer was found to accompany changes in phase and color observed upon cryogrinding the two polymorphs. Model-free and model-fitting studies of the dehydration kinetics of piroxicam monohydrate (PM) showed the dependence of activation energy ( Ea) on both isothermal and non-isothermal heating conditions, and on the fraction of conversion. In the constant-E a region, isothermal dehydration follows the two

  13. Structure-property relationships of small bandgap conjugated polymers for solar cells.

    Science.gov (United States)

    Hellström, Stefan; Zhang, Fengling; Inganäs, Olle; Andersson, Mats R

    2009-12-01

    Conjugated polymers as electron donors in solar cells based on donor/acceptor combinations are of great interest, partly due to the possibility of converting solar light with a low materials budget. Six small bandgap polymers with optical bandgap ranging from 1.0-1.9 eV are presented in this paper. All polymers utilize an electron donor-acceptor-donor (DAD) segment in the polymer backbone, creating a partial charge-transfer, to decrease the bandgap. The design, synthesis and the optical characteristics as well as the solar cell characteristics of the polymers are discussed. The positions of the energy levels of the conjugated polymer relative to the electron acceptor are of significant importance and determine not only the driving force for exciton dissociation but also the maximum open-circuit voltage. This work also focuses on investigating the redox behavior of the described conjugated polymers and electron acceptors using square wave voltammetry. Comparing the electrochemical data gives important information of the structure-property relationships of the polymers.

  14. Structure/Property Relationships of Siloxane-Based Liquid Crystalline Materials

    Science.gov (United States)

    1992-05-01

    AD-A266 676 IImNflhIIIII WL-TR-92-4051 STRUCIUREIPROPERTY RELATIONSHIPS OF SILOXANE- BASED LIQUID CRYSTALLINE MATERIALS Timothy J. Bunning Herbert E...FUNDING NUMBERSSTRUCTURE/PROPERTY RELATIONSHIPS OF SILOXANE-BASED P: 612 LIQUID CRYSTALLINE MATERIALS PR: 624022 TA: 04 6 AUTHOR(S) W: 0 B unning, T.J...TY UISP1CTM D B DistbuationlI -vi Availability Codes Avail and/or Dist Special -Il V. SYNTHESIZED SILOXANE LIOUD CRYSTALLINE MATERIALS (Results and

  15. The Relationships between Rheological Properties and Structural Changes of Chilled Abalone Meat

    Institute of Scientific and Technical Information of China (English)

    GAO Xin; ZHANG Zhaohui; TANG Zhixu; TASHIRO Yuri; OGAWA Hiroo

    2003-01-01

    The quantitative correlation between theological properties and structural characteristic values of chilled abalone meat was studied. Structural changes were observed, and these values were enumerated using image processing and analysis technique. Structural changes in the myofibrils and collagen fibrils were the greatest in chilling for 24 h. After chilling for 48 h, similar structures of vertical and cross sections were observed. For chilling from 0h to 72h, the instantaneous modulus E0 of the both section meat decreases gradually with time, but no significant differences were observed after chilling for 48 h.The relaxation time and viscosity of both sections attained the same values for the same chilling time, but increased gradually with increasing chilling time. Meanwhile, a negative correlation between the structural characteristic values (Dm, Am,Rvm), and rheological properties (E1,τi,η1) clearly exists. Some logarithmic expressions have been obtained for these negative correlations. These results suggest that the difference in rheological properties between the cross and vertical sections was mainly due to the structural changes of myofibrils and collagen fibrils, and rheological properties are influenced quantitatively by the structural characteristic values for chilling from 0 h to 72 h.

  16. A Study the relationship between composition, structure and properties of ductile iron in continuous casting

    OpenAIRE

    2011-01-01

    The developed empirical relationships have practical significance and used for determine the structural composition of iron on known data of express-analysis and for optimization technical process of obtaining castings of ductile iron at Public corporation «Gomel foundry «TSENTROLIT».

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

    DEFF Research Database (Denmark)

    Schaefers, Christoph; Sanderson, Hans; Boshof, Udo;

    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...

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

    Science.gov (United States)

    Martinetti, Luca

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

  19. A Quantitative Structure Property Relationship for Prediction of Flash Point of Alkanes Using Molecular Connectivity Indices

    Institute of Scientific and Technical Information of China (English)

    Morteza Atabati; Reza Emamalizadeh

    2013-01-01

    Many structure-property/activity studies use graph theoretical indices,which are based on the topological properties of a molecule viewed as a graph.Since topological indices can be derived directly from the molecular structure without any experimental effort,they provide a simple and straightforward method for property prediction.In this work the flash point of alkanes was modeled by a set of molecular connectivity indices (x),modified molecular connectivity indices (mx(1)h) and valance molecular connectivity indices (mxv),with mxv calculated using the hydrogen perturbation.A stepwise Multiple Linear Regression (MLR) method was used to select the best indices.The predicted flash points are in good agreement with the experimental data,with the average absolute deviation 4.3 K.

  20. Structure-property relationships: Synthesis and characterization of Perovskite-related transition metal oxides

    Science.gov (United States)

    Whaley, Louis

    The fundamental structural component of perovskite-related phases is the octahedrally coordinated transition metal ion, symbolized as BO6 . Corner-sharing networks of BO6 octahedra are present in perovskites and related Ruddlesden-Popper Phases, ABO3 and AO(ABO 3)n, respectively. Face-sharing octahedra arranged into columns are characteristic of hexagonal, perovskite-related phases, and the relationship will be described in detail in Chapter 1. Edge sharing octahedra are characteristic of Keggin- and Lindquist-type polyoxometallates, which at first glance, seem unconnected from perovskites. However, Chapter 1 will show the deep connections among all of the phases mentioned above, by starting with perovskite phases. Temperature- and field-dependent, magnetic and electronic transitions are linked to the structure by overlap of metal d-orbitals with oxygen 2p orbitals, and (in special cases) direct d-d overlap. A mixed-transition metal oxide with two or more type of B ions provides an environment in which dissimilar B-ion orbitals can interact via exchange of charge carriers (hole or electron transport). The general goal in choosing two B ions is to provide an opportunity for the large combined magnetic moment and a low barrier to hopping of charge carriers, achieved by pairing a 3d-ion having 3 to 5 unpaired d-electrons, with a 4d or 5d transition metal ion, having 1 or 2 unpaired electrons, such as Fe(III) and Mo(V), which have compatible reduction potentials (i.e., they can co-exist in the same oxide, and exchange takes place with a low barrier). This research includes the following systems: an n = 2 Ruddlesden-Popper (RP) phase, Sr3Fe5/4Mo3/4O6.9, containing 3-7% Sr2FeMoO6, as intergrowths (not separate crystal grains, by high-resolution transmission electron microscopy), and G-type antiferromagnetism below 150°K and a "partial spin-reorientation transition" by powder neutron diffraction (PND), not previously reported for n = 2 RP phases in the Sr-Fe-Mo-O system

  1. Quantitative structure-property relationship of aromatic sulfur-containing carboxylates

    Institute of Scientific and Technical Information of China (English)

    LIU Xin-hui; YANG Zhi-feng; WANG Lian-sheng

    2003-01-01

    Based on quantum chemical calculations, TLSER model (theoretical linear solvation energy relationships) and atomic charge approach were applied to model the partition properties(water solubility and octanol/water partition coefficient) of 96 aromatic sulfur-containing carboxylates, including phenylthio, phenylsulfinyl and phenylsulfonyl carboxylates. In comparison with TLSER models, the atomic charge models are more accurate and reliable to predict the partition properties of the kind of compounds. For the atomic charge models, the molecular descriptors are molecular surface area( S ), molecular shape( O ), weight( Mw ), net charges on carboxyl group( QOC ), net charges of nitrogen atoms(Q N), and the most negative atomic charge( q- ) of the solute molecule. For water solubility (log Sw ) and octanol/water partition coefficient(log Kow), the correction coefficients r2adj(adjusted for degrees of freedom) are 0.936 and 0.938, and the standard deviations are 0.364 and 0.223, respectively.

  2. Complementary study based on DFT to describe the structure and properties relationship of diblock copolymer based on PVK and PPV

    Energy Technology Data Exchange (ETDEWEB)

    Mbarek, M.; Abbassi, F.; Alimi, K., E-mail: kamel.alimi@fsm.rnu.tn

    2016-09-15

    The structure-properties relationships of copolymer involving N-vinylcarbazole (PVK) and poly (p-phenylene-vinylene) (PPV) blocks, denoted PVK–PPV, was investigated by calculations based on density functional theory (DFT) and completed by experimental analyses. Thus, vibrational, optical and emission spectra of model compound have been simulated and compared to the experiments observations published recently. Ionization potentials (IPs), electron affinities (EAs) and energy gaps were determined. Furthermore, quantum yields, radiative and nonradiative exciton lifetime was highlighted.

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

    KAUST Repository

    Luxenhofer, Robert

    2011-07-01

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

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

    Science.gov (United States)

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

    2014-11-18

    CONSPECTUS: Considerable effort in the past decade has been extended toward achieving computationally affordable theoretical methods for accurate prediction of the structure and properties of materials. Theoretical predictions of solids began decades ago, but only recently have solid-state quantum techniques become sufficiently reliable to be routinely chosen for investigation of solids as quantum chemistry techniques are for isolated molecules. Of great interest are ab initio predictive theories for solids that can provide atomic scale insights into properties of bulk materials, interfaces, and nanostructures. Adaption of the quantum chemical framework is challenging in that no single theory exists that provides prediction of all observables for every material type. However, through a combination of interdisciplinary efforts, a richly textured and substantive portfolio of methods is developing, which promise quantitative predictions of materials and device properties as well as associated performance analysis. Particularly relevant for device applications are organic semiconductors (OSC), with electrical conductivity between that of insulators and that of metals. Semiconducting small molecules, such as aromatic hydrocarbons, tend to have high polarizabilities, small band-gaps, and delocalized π electrons that support mobile charge carriers. Most importantly, the special nature of optical excitations in the form of a bound electron-hole pairs (excitons) holds significant promise for use in devices, such as organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), and molecular nanojunctions. Added morphological features, such as curvature in aromatic hydrocarbon structure, can further confine the electronic states in one or more directions leading to additional physical phenomena in materials. Such structures offer exploration of a wealth of phenomenology as a function of their environment, particularly due to the ability to tune their electronic

  6. 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...

  7. Further properties of causal relationship: causal structure stability, new criteria for isocausality and counterexamples

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Parrado, Alfonso [Departamento de Fisica Teorica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao (Spain); Sanchez, Miguel [Departamento de Geometria y Topologia, Facultad de Ciencias, Universidad de Granada, Avenida Fuentenueva s/n, 18071 Granada (Spain)

    2005-11-07

    Recently (Garcia-Parrado and Senovilla 2003 Class. Quantum Grav. 20 625-64) the concept of causal mapping between spacetimes, essentially equivalent in this context to the chronological map defined in abstract chronological spaces, and the related notion of causal structure, have been introduced as new tools to study causality in Lorentzian geometry. In the present paper, these tools are further developed in several directions such as (i) causal mappings-and, thus, abstract chronological ones-do not preserve two levels of the standard hierarchy of causality conditions (however, they preserve the remaining levels as shown in the above reference), (ii) even though global hyperbolicity is a stable property (in the set of all time-oriented Lorentzian metrics on a fixed manifold), the causal structure of a globally hyperbolic spacetime can be unstable against perturbations; in fact, we show that the causal structures of Minkowski and Einstein static spacetimes remain stable, whereas that of de Sitter becomes unstable, (iii) general criteria allow us to discriminate different causal structures in some general spacetimes (e.g. globally hyperbolic, stationary standard); in particular, there are infinitely many different globally hyperbolic causal structures (and thus, different conformal ones) on R{sup 2} (iv) plane waves with the same number of positive eigenvalues in the frequency matrix share the same causal structure and, thus, they have equal causal extensions and causal boundaries.

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

    Science.gov (United States)

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

    2015-07-01

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

  9. Structure-property relationships in halogenbenzoic acids: Thermodynamics of sublimation, fusion, vaporization and solubility.

    Science.gov (United States)

    Zherikova, Kseniya V; Svetlov, Aleksey A; Kuratieva, Natalia V; Verevkin, Sergey P

    2016-10-01

    Temperature dependences of vapor pressures for 2-, 3-, and 4-bromobenzoic acid, as well as for five isomeric bromo-methylbenzoic acids were studied by the transpiration method. Melting temperatures and enthalpies of fusion for all isomeric bromo-methylbenzoic acids and 4-bromobenzoic acid were measured with a DSC. The molar enthalpies of sublimation and vaporization were derived. These data together with results available in the literature were collected and checked for internal consistency using a group-additivity procedure and results from X-ray structural diffraction studies. Specific (hydrogen bonding) interactions in the liquid and in the crystal phase of halogenbenzoic acids were quantified based on experimental values of vaporization and sublimation enthalpies. Structure-property correlations of solubilities of halogenobenzoic acids with sublimation pressures and sublimation enthalpies were developed and solubilities of bromo-benzoic acids were estimated. These new results resolve much of the ambiguity in the available thermochemical and solubility data on bromobenzoic acids. The approach based on structure property correlations can be applied for the assessment of water solubility of sparingly soluble drugs.

  10. 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

  11. Experimental and theoretical study on the structure-property relationship of novel 1-aryl-3-methylsuccinimides

    Science.gov (United States)

    Banjac, Nebojša R.; Božić, Bojan Đ.; Mirković, Jelena M.; Vitnik, Vesna D.; Vitnik, Željko J.; Valentić, Nataša V.; Ušćumlić, Gordana S.

    2017-02-01

    A series of ten 1-aryl-3-methylsuccinimides was synthesized and their solvatochromic properties were studied in a set of fifteen binary solvent mixtures. The solute-solvent interactions were analyzed on the basis of the linear solvation energy relationship (LSER) concept proposed by Kamlet and Taft. The electronic effect of the substituents on the UV-Vis absorption and NMR spectra was analyzed using the simple Hammett equation. Moreover, the B3LYP, CAM-B3LYP, and M06-2X functionals using the 6-311G(d,p) basic set have been assessed in light of the position of experimental absorption maxima obtained for these compounds. The integration grid effects have also been evaluated. An interpretation of the substituent-effect transmission through the molecular skeleton and the nature of the HOMO and LUMO orbitals based on quantum-chemical calculations is given. The values of partial atomic charges from the atomic polar tenzors (APT), natural population analysis (NBO), and charges fit to the electrostatic potential using the B3LYP, CAM-B3LYP, and M06-2X methods are produced and correlated with different experimental properties. In order to estimate the chemical activity of the molecule, the molecular electrostatic potential (MEP) surface map is calculated for the optimized geometry of 1-phenyl-3-methylsuccinimide.

  12. Structure-property relationships of dissimilar friction stir welded aluminum alloys

    Science.gov (United States)

    Quinones, Rogie Irwin Rodriguez

    In this work, the relationship between microstructure and mechanical properties of dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys were evaluated. Experimental results from this study revealed that static strength increased with the tool rotational speed and was correlated with the material intermixing. Fully-reversed low cycle fatigue experimental results showed an increase in the strain hardening properties as well as the number of cycles-to-failure as the tool rotational speed was increased. Furthermore, under both static and cyclic loading, fracture of the joint was dominated by the AA6061 alloy side of the weld. In addition, inspection of the fatigue surfaces revealed that cracks initiated from intermetallic particles located near the surface. In order to determine the corrosion resistance of the dissimilar joint, corrosion defects were produced on the crown surface of the weld by static immersion in 3.5% NaCl for various exposure times. Results revealed localized corrosion damage in the thermo-mechanically affected and heat affected zones. Results demonstrated a decrease in the fatigue life, with evidence of crack initiation at the corrosion defects; however, the fatigue life was nearly independent of the exposure time. This can be attributed to total fatigue life dominated by incubation time. Furthermore, two types of failure were observed: fatigue crack initiation in the AA6061 side at high strain amplitudes (>0.3%); and fatigue crack initiation in the AA7050 side at low strain amplitudes (friction stir welded joints in order to capture the crack initiation and propagation in as-welded and pre-corroded conditions. Good correlation between experimental fatigue results and the model was achieved based on the variation in the initial defect size, microstructure, and mechanical properties of the dissimilar friction stir welded AA6061-to-AA7050 aluminum alloys.

  13. Structure and immunomodulatory property relationship in NapA of Borrelia burgdorferi.

    Science.gov (United States)

    Codolo, Gaia; Papinutto, Elena; Polenghi, Alessandra; D'Elios, Mario Milco; Zanotti, Giuseppe; de Bernard, Marina

    2010-12-01

    NapA from Borrelia burgdorferi is a member of the Dps-like protein family with specific immunomodulatory properties; in particular, NapA is able to induce the expression of IL-23 in neutrophils and monocytes, as well as the expression of IL-6, IL-1β, and transforming growth factor beta (TGF-β) in monocytes, via Toll-like receptor (TLR) 2. Such an activity on innate immune cells triggers a synovial fluid Th17 response. Here we report the crystal structure of NapA, determined at 2.6Å resolution, which shows that the quaternary structure of the protein is that of a dodecamer with 23 symmetry, typical of the proteins of the family. We also demonstrate that the N- and C-terminal tails, which are flexible and not visible in the crystal, are not relevant for its pro-Th17 activity. Based on the crystal structure and on the comparison with the structure of the orthologous protein from Helicobacter pylori, HP-NAP, we hypothesize that the charge distributions on the two proteins' surfaces are responsible for the interaction with TLR2 and for the different behaviors in modulating the immune response.

  14. Preparation of TiO2/epoxy nanocomposites by ultrasonic dispersion and their structure property relationship.

    Science.gov (United States)

    Bittmann, Birgit; Haupert, Frank; Schlarb, Alois Karl

    2011-01-01

    By the insertion of nanoparticles into a polymer matrix a considerable improvement of mechanical properties can be achieved. Therefore, a homogeneous distribution of fillers within the matrix is required. In the present paper the dispersion of TiO(2)-nanoparticles in a DGEBA (diglycidyl ether of bisphenol A) epoxy resin by means of an ultrasonic horn was studied. The systematic examination of process parameters of a previous study was completed in order to determine the optimum processing window leading to a good dispersion result without degrading the molecular structure of the epoxy resin. Therefore, particle sizes were examined using a dynamic light scattering device, and the effect of the ultrasonic treatment on the resin was surveyed by FT-IR spectroscopy (Fourier transform infrared spectroscopy). Furthermore, the mechanical performance of the nanocomposites was examined for various contents of TiO(2)-nanoparticles to show that the materials prepared by ultrasonic dispersion show an improved property's profile. In order to understand the reinforcing mechanisms of nanoparticles in the polymer matrix providing improved mechanical properties, scanning electron microscope (SEM) pictures of the fracture surfaces of the samples were carried out, which revealed that nanocomposites show a significantly rougher surface than the neat epoxy resin. This indicates a change in the fracture mechanisms.

  15. Antioxidant properties of phenolic Schiff bases: structure-activity relationship and mechanism of action.

    Science.gov (United States)

    Anouar, El Hassane; Raweh, Salwa; Bayach, Imene; Taha, Muhammad; Baharudin, Mohd Syukri; Di Meo, Florent; Hasan, Mizaton Hazizul; Adam, Aishah; Ismail, Nor Hadiani; Weber, Jean-Frédéric F; Trouillas, Patrick

    2013-11-01

    Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure-antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH.

  16. Chlorophenol sorption on multi-walled carbon nanotubes: DFT modeling and structure-property relationship analysis.

    Science.gov (United States)

    Watkins, Marquita; Sizochenko, Natalia; Moore, Quentarius; Golebiowski, Marek; Leszczynska, Danuta; Leszczynski, Jerzy

    2017-02-01

    The presence of chlorophenols in drinking water can be hazardous to human health. Understanding the mechanisms of adsorption under specific experimental conditions would be beneficial when developing methods to remove toxic substances from drinking water during water treatment in order to limit human exposure to these contaminants. In this study, we investigated the sorption of chlorophenols on multi-walled carbon nanotubes using a density functional theory (DFT) approach. This was applied to study selected interactions between six solvents, five types of nanotubes, and six chlorophenols. Experimental data were used to construct structure-adsorption relationship (SAR) models that describe the recovery process. Specific interactions between solvents and chlorophenols were taken into account in the calculations by using novel specific mixture descriptors.

  17. 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.

  18. Ferroelectric, ferromagnetic and optical properties of KBiFe2O5 thin film: a structure property relationship

    Science.gov (United States)

    Jalaja, M. A.; Predeep, P.; Dutta, Soma

    2017-01-01

    KBiFe2O5 thin film was prepared by spin-coating on platinized (111) Si wafer and characterized for its structure, microstructure, ferroelectric, magnetic and optical properties. X-ray diffraction (XRD) revealed a noncentrosymmetric, orthorhombic crystal structure of KBiFe2O5. The well-distributed dense microstructure with large grain and narrow grain boundaries in KBiFe2O5 enhanced its ferroelectric properties. The strong, frequency-dependent behavior of the ferroelectric hysteresis loop suggested the leaky nature of the material. Piezoelectricity was confirmed by determining the piezoelectric charge coefficients (d 33 = 2.82 nm V-1 at positive bias and 3.195 nm V-1 at negative bias voltage) from the field versus the displacement plot. The weak ferromagnetism of the film is attributed to the high spin state of Fe3+ in the FeO4 tetrahedron of KBiFe2O5. Optical properties (refractive indices and extinction coefficients) are studied from the reflectance spectrum. The refractive indices are higher in the visible region and showed a normal dispersion in the blue region. The bandgap of the film was calculated to be 1.61 eV.

  19. 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.

  20. Synthesis and Structure-Property Relationships of Phosphole-Based π Systems and Their Applications in Organic Solar Cells.

    Science.gov (United States)

    Matano, Yoshihiro

    2015-06-01

    Phosphole is a chemically tunable heterole, and its π-conjugated derivatives are potential candidates for optoelectronic materials. This account describes recent developments in the synthesis and structure-property relationships of π-conjugated phosphole derivatives made by my research group. Thiophene-phosphole-styrene, phosphole-acetylene-arene, oligophosphole, polyphosphole, areno[c]phosphole, and phosphole-heterole π systems are synthesized using titanacycle-mediated metathesis and palladium-catalyzed cross-coupling reactions. The structural, optical, and electrochemical properties of selected compounds are discussed. Initial results on some applications of thiophene-phosphole copolymers, acenaphtho[c]phospholes, and amine-terthiophene-phosphole donor-π-acceptor dyes in organic solar cells are described. These results give valuable information and guidelines for designing new phosphorus-containing organic materials for molecular electronics.

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

    CERN Document Server

    Nasef, M M

    2003-01-01

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

  2. 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.

  3. Rare earth-doped lead borate glasses and transparent glass-ceramics: Structure-property relationship

    Science.gov (United States)

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

    2011-08-01

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

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

    Science.gov (United States)

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

    2011-08-15

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

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

    CERN Document Server

    Santos, M C D

    2000-01-01

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

  6. Selenium-Containing Fused Bicyclic Heterocycle Diselenolodiselenole: Field Effect Transistor Study and Structure-Property Relationship.

    Science.gov (United States)

    Debnath, Sashi; Chithiravel, Sundaresan; Sharma, Sagar; Bedi, Anjan; Krishnamoorthy, Kothandam; Zade, Sanjio S

    2016-07-20

    The first application of the diselenolodiselenole (C4Se4) heterocycle as an active organic field effect transistor materials is demonstrated here. C4Se4 derivatives (2a-2d) were obtained by using a newly developed straightforward diselenocyclization protocol, which includes the reaction of diynes with selenium powder at elevated temperature. C4Se4 derivatives exhibit strong donor characteristics and planar structure (except 2d). The atomic force microscopic analysis and thin-film X-ray diffraction pattern of compounds 2a-2d indicated the formation of distinct crystalline films that contain large domains. A scanning electron microscopy study of compound 2b showed development of symmetrical grains with an average diameter of 150 nm. Interestingly, 2b exhibited superior hole mobility, approaching 0.027 cm(2) V(-1) s(-1) with a transconductance of 9.2 μS. This study correlate the effect of π-stacking, Se···Se intermolecular interaction, and planarity with the charge transport properties and performance in the field effect transistor devices. We have shown that the planarity in C4Se4 derivatives was achieved by varying the end groups attached to the C4Se4 core. In turn, optoelectronic properties can also be tuned for all these derivatives by end-group variation.

  7. Relationship between structure and antioxidative properties of some 3-formylchromone derivatives.

    Science.gov (United States)

    Sersen, F; Loos, D; Mezesová, L; Lácová, M

    2008-07-01

    Flavonoids, which generally exhibit very good antioxidant properties, contain the chromone unity. The work elucidates the relation between chemical structure of chromones and their ability to scavenge DPPH radicals. The work deals with antioxidative properties of some hydroxy derivatives of 3-formylchromones (without substituent, 6-hydroxy-, 7-hydroxy-, 7,8-dihydroxy-). It was found that the last two derivatives scavenge DPPH radicals, whereas the first two ones do not. It was demonstrated that the presence and location of hydroxyl groups play a crucial role for antioxidative activity of 3-formylchromones. The scavenging of DPPH radicals runs through H(+) abstraction from hydroxyl groups of formylchromones. The DPPH scavenging by 3-formylchromones with hydroxyl group in the 7th position is connected with the formation of more stable form of anion than in the case of 6-hydroxy-3-formylchromone. Calculation heats of formations of studied formylchromone anions confirmed this fact. All studied 3-formylchromones did not scavenge HO( ) radicals, what supports H(+) abstraction mechanism of DPPH scavenging.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-02-23

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

  9. Structure-property relationships in cubic cuprous iodide: A novel view on stability, chemical bonding, and electronic properties.

    Science.gov (United States)

    Pishtshev, A; Karazhanov, S Zh

    2017-02-14

    Based on the combination of density functional theory and theory-group methods, we performed systematic modeling of γ-CuI structural design at the atomistic level. Being started from the metallic copper lattice, we treated a crystal assembly as a stepwise iodination process characterized in terms of a sequence of intermediate lattice geometries. These geometries were selected and validated via screening of possible structural transformations. The genesis of chemical bonding was studied for three structural transformations by analyzing the relevant changes in the topology of valence electron densities. We determined structural trends driven by metal-ligand coupling. This allowed us to suggest the improved scenario of chemical bonding in γ-CuI. In particular, the unconventional effect of spatial separation of metallic and covalent interactions was found to be very important with respect to the preferred arrangements of valence electrons in the iodination process. We rigorously showed that useful electronic and optical properties of γ-CuI originate from the combination of two separated bonding patterns-strong covalency established in I-Cu tetrahedral connections and noncovalent interactions of copper cores is caused by the 3d(10) closed-shell electron configurations. The other finding of ours is that the self-consistency of the GW calculations is crucial for correctly determining the dynamic electronic correlations in γ-CuI. Detail reinvestigation of the quasi-particle energy structure by means of the self-consistent GW approach allowed us to explain how p-type electrical conductivity can be engineered in the material.

  10. Structure-property relationships in cubic cuprous iodide: A novel view on stability, chemical bonding, and electronic properties

    Science.gov (United States)

    Pishtshev, A.; Karazhanov, S. Zh.

    2017-02-01

    Based on the combination of density functional theory and theory-group methods, we performed systematic modeling of γ-CuI structural design at the atomistic level. Being started from the metallic copper lattice, we treated a crystal assembly as a stepwise iodination process characterized in terms of a sequence of intermediate lattice geometries. These geometries were selected and validated via screening of possible structural transformations. The genesis of chemical bonding was studied for three structural transformations by analyzing the relevant changes in the topology of valence electron densities. We determined structural trends driven by metal-ligand coupling. This allowed us to suggest the improved scenario of chemical bonding in γ-CuI. In particular, the unconventional effect of spatial separation of metallic and covalent interactions was found to be very important with respect to the preferred arrangements of valence electrons in the iodination process. We rigorously showed that useful electronic and optical properties of γ-CuI originate from the combination of two separated bonding patterns—strong covalency established in I-Cu tetrahedral connections and noncovalent interactions of copper cores is caused by the 3d10 closed-shell electron configurations. The other finding of ours is that the self-consistency of the GW calculations is crucial for correctly determining the dynamic electronic correlations in γ-CuI. Detail reinvestigation of the quasi-particle energy structure by means of the self-consistent GW approach allowed us to explain how p-type electrical conductivity can be engineered in the material.

  11. Solvent effects on the absorption spectra of potentially pharmacologically active 5-alkyl-5-arylhydantoins: A structure-property relationship study

    Directory of Open Access Journals (Sweden)

    Hmuda Sleem F.

    2013-01-01

    Full Text Available To obtain an insight into the interactions of potential anticonvulsant drugs with their surrounding, two series of 5-methyl-5-aryl- and 5-ethyl-5-arylhydantoins were synthesized and their absorption spectra were recorded in the region from 200 to 400 nm in a set of selected solvents. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen bonding interactions on the absorption maxima shifts were analyzed by means of the linear solvation energy relationship (LSER concept of Kamlet and Taft. The ratio of the contributions of specific and nonspecific solvent-solute interactions were correlated with the corresponding ADME properties of the studied compounds. The correlation equations were combined with different physicochemical parameters to generate new equations, which demonstrate the reasonable relationships between solvent-solute interactions and the structure-activity parameters. [Projekat Ministarstva nauke Republike Srbije, br. 172013

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

    Directory of Open Access Journals (Sweden)

    Bin Cheng

    2011-04-01

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

  13. Structure-property relationship in polyethylene reinforced by polyethylene-grafted multi-walled carbon nanotubes.

    Science.gov (United States)

    Causin, Valerio; Yang, Bing-Xing; Marega, Carla; Goh, Suat Hong; Marigo, Antonio

    2008-04-01

    Polyethylene-grafted multiwalled carbon nanotubes (PE-g-MWNT) were used to reinforce polyethylene (PE). The nanocomposites possessed not only improved stiffness and strength, but also increased ductility and toughness. The effects on the structure and morphology of composites due to pristine multiwalled carbon nanotubes (MWNT) and PE-g-MWNT were studied and compared using small angle X-ray scattering (SAXS), wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The SAXS long period, crystalline layer thickness and crystallinity of polymer lamellar stacks were found to decrease significantly in MWNT composites, while the decreases were much smaller in PE-g-MWNT composites. PE-g-MWNT allowed a more efficient and unhindered crystallization at a lamellar level, while MWNT disrupted the order of lamellar stacks, probably because of their tendency to aggregate. The SAXS crystallinity and the mechanical properties of the composites showed similar trends as a function of MWNT content. This suggested that the improvement of the interfacial strength between polymer and carbon nanotubes was a result of synergistic effects of better dispersion of the filler, better stress transfer, due to the grafting of polymer and MWNT, and the nucleation of a crystalline phase around MWNT. The latter effect was confirmed by measurements of kinetics of non-isothermal crystallization.

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

    Science.gov (United States)

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

    2017-02-27

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

  15. Structure-property-glass transition relationships in non-isocyanate polyurethanes investigated by dynamic nanoindentation

    Science.gov (United States)

    Weyand, Stephan; Blattmann, Hannes; Schimpf, Vitalij; Mülhaupt, Rolf; Schwaiger, Ruth

    2016-07-01

    Newly developed green-chemistry approaches towards the synthesis of non-isocyanate polyurethane (NIPU) systems represent a promising alternative to polyurethanes (PU) eliminating the need for harmful ingredients. A series of NIPU systems were studied using different nanoindentation techniques in order to understand the influence of molecular parameters on the mechanical behavior. Nanoindentation revealed a unique characteristic feature of those materials, i.e. stiffening with increasing deformation. It is argued that the origin of this observed stiffening is a consequence of the thermodynamic state of the polymer network, the molecular characteristics of the chemical building blocks and resulting anisotropic elastic response of the network structure. Flat-punch nanoindentation was applied in order to characterize the constitutive viscoelastic nature of the materials. The complex modulus shows distinct changes as a function of the NIPU network topology illustrating the influence of the chemical building blocks. The reproducibility of the data indicates that the materials are homogeneous over the volumes sampled by nanoindentation. Our study demonstrates that nanoindentation is very well-suited to investigate the molecular characteristics of NIPU materials that cannot be quantified in conventional experiments. Moreover, the technique provides insight into the functional significance of complex molecular architectures thereby supporting the development of NIPU materials with tailored properties.

  16. 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.

  17. Quantitative Structure-property Relationship Studies on Amino Acid Conjugates of Jasmonic Acid as Defense Signaling Molecules

    Institute of Scientific and Technical Information of China (English)

    Zu-Guang Li; Ke-Xian Chen; Hai-Ying Xie; Jian-Rong Gao

    2009-01-01

    Jasmonates and related compounds, including amino acid conjugates of jasmonic acid, have regulatory functions in the signaling pathway for plant developmental processes and responses to the complex equilibrium of biotic and abiotic stress.But the molecular details of the signaling mechanism are still poorly understood. Statistically significant quantitative structure-property relationship models (r2 > 0.990) constructed by genetic function approximation and molecular field analysis were generated for the purpose of deriving structural requirements for lipophilicity of amino acid conjugates of jasmonic acid. The best models derived in the present study provide some valuable academic information in terms of the 213D-descriptors influencing the lipophilicity, which may contribute to further understanding the mechanism of exogenous application of jasmonates in their signaling pathway and designing novel analogs ofjasmonic acid as ecological pesticides.

  18. Glycyrrhetinic Acid and Its Derivatives: Anti-Cancer and Cancer Chemopreventive Properties, Mechanisms of Action and Structure- Cytotoxic Activity Relationship.

    Science.gov (United States)

    Roohbakhsh, Ali; Iranshahy, Milad; Iranshahi, Mehrdad

    2016-01-01

    The anti-cancer properties of liquorice have been attributed, at least in part, to glycyrrhizin (GL). However, GL is not directly absorbed through the gastrointestinal tract. It is hydrolyzed to 18-β-glycyrrhetinic acid (GA), the pharmacologically active metabolite, by human intestinal microflora. GA exhibits remarkable cytotoxic and anti-tumor properties. The pro-apoptotic targets and mechanisms of action of GA have been extensively studied over the past decade. In addition, GA is an inexpensive and available triterpene with functional groups (COOH and OH) in its structure, which make it an attractive lead compound for medicinal chemists to prepare a large number of analogues. To date, more than 400 cytotoxic derivatives have been prepared on the basis of GA scaffold, including 128 cytotoxic derivatives with IC50 values less than 30 µM. Researchers have also succeeded in synthesizing very potent cytotoxic derivatives with IC50s ≤ 1 µM. Studies have shown that the introduction of a double bound at the C1-C2 position combined with an electronegative functional group, such as CN, CF3 or iodine at C2 position, and the oxidation of the hydroxyl group of C3 to the carbonyl group, significantly increased cytotoxicity. This review describes the cytotoxic and anti-tumor properties of GA and its derivatives, targets and mechanisms of action and provides insight into the structure-activity relationship of GA derivatives.

  19. 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 medici

  20. 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 (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

  1. Direct, functional relationship between structural and optical properties in titanium-incorporated gallium oxide nanocrystalline thin films

    Science.gov (United States)

    Manandhar, S.; Ramana, C. V.

    2017-02-01

    We present an approach to design Ga2O3-based materials with tunable optical properties. In the Ti-doped Ga2O3 model system, where the Ti content (x) was varied up to ˜5 at. %, Ti induced significant effects on the structural and optical properties. Single-phase β-Ga2O3 formation occurs for a lower Ti content (≤1.5 at. %); however, composite-oxide (Ga2O3-TiO2) formation occurs for a higher Ti content. While band gap reduction (Eg ˜ 0.9 eV) coupled with refractive index (n) enhancement occurs, indicating the electronic-structure modification, with Ti incorporation, the changes are dominant only in the Ga2O3-TiO2-composite. A direct, functional Ti(x)-Eg-n relationship was found, which suggests that tailoring the optical quality and performance of Ga-Ti-O is possible by tuning the Ti content and structure.

  2. Quantitative structure-property relationships for chemical functional use and weight fractions in consumer articles

    Science.gov (United States)

    Chemical functional use -- the functional role a chemical plays in processes or products -- may be a useful heuristic for predicting human exposure potential in that it comprises information about the compound's likely physical properties and the product formulations or articles ...

  3. Structure-Property Relationships of Poly(lactide)-based Triblock and Multiblock Copolymers

    Science.gov (United States)

    Panthani, Tessie Rose

    Replacing petroleum-based plastics with alternatives that are degradable and synthesized from annually renewable feedstocks is a critical goal for the polymer industry. Achieving this goal requires the development of sustainable analogs to commodity plastics which have equivalent or superior properties (e.g. mechanical, thermal, optical etc.) compared to their petroleum-based counterparts. This work focuses on improving and modulating the properties of a specific sustainable polymer, poly(lactide) (PLA), by incorporating it into triblock and multiblock copolymer architectures. The multiblock copolymers in this work are synthesized directly from dihydroxy-terminated triblock copolymers by a simple step-growth approach: the triblock copolymer serves as a macromonomer and addition of stoichiometric quantities of either an acid chloride or diisocyanate results in a multiblock copolymer. This work shows that over wide range of compositions, PLA-based multiblock copolymers have superior mechanical properties compared to triblock copolymers with equivalent chemical compositions and morphologies. The connectivity of the blocks within the multiblock copolymers has other interesting consequences on properties. For example, when crystallizable poly(L-lactide)-based triblock and multiblock copolymers are investigated, it is found that the multiblock copolymers have much slower crystallization kinetics. Additionally, the total number of blocks connected together is found to effect the linear viscoelastic properties as well as the alignment of lamellar domains under uniaxial extension. Finally, the synthesis and characterization of pressure-sensitive adhesives based upon renewable PLA-containing triblock copolymers and a renewable tackifier is detailed. Together, the results give insight into the effect of chain architecture, composition, and morphology on the mechanical behavior, thermal properties, and rheological properties of PLA-based materials.

  4. 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.

  5. Nutritional property of endosperm starches from maize mutants: a parabolic relationship between slowly digestible starch and amylopectin fine structure.

    Science.gov (United States)

    Zhang, Genyi; Ao, Zihua; Hamaker, Bruce R

    2008-06-25

    The relationship between the slow digestion property of cooked maize starch and its molecular fine structure was investigated. Results of the in vitro Englyst assay showed a range of rapidly digestible starch (RDS) (70.1-98.9%), slowly digestible starch (SDS) (0.2-20.3%), and resistant starch (RS) (0.0-13.7%) among the tested maize mutant flour samples. Further analysis showed that amylose content was significantly correlated ( R = 0.763, P analysis revealed a parabolic relationship between SDS content and the weight ratio of amylopectin short chains (DP /= 13, named LF), which means amylopectin with a higher amount of either short chains or long chains can produce relatively high amounts of SDS. Furthermore, debranching analysis of the SDS materials from samples with the highest and lowest weight ratios of SF/LF (both had a high amount SDS) showed significantly different profiles, indicating there is not a uniform molecular structure for SDS. Thus, genetic mutants of maize samples have a good potential to provide raw starch materials of high nutritional quality. An additional finding showed that a simple and comparably high-throughput technique of Rapid Visco-Analyzer (RVA) can be used to screen genetic mutants on the basis of their RVA profiles.

  6. A novel approach to study the structure-property relationships and applications in living systems of modular Cu2+ fluorescent probes

    Science.gov (United States)

    She, Mengyao; Yang, Zheng; Hao, Likai; Wang, Zhaohui; Luo, Tianyou; Obst, Martin; Liu, Ping; Shen, Yehua; Zhang, Shengyong; Li, Jianli

    2016-08-01

    A series of Cu2+ probe which contains 9 probes have been synthesized and established. All the probes were synthesized using Rhodamine B as the fluorophore, conjugated to various differently substituted cinnamyl aldehyde with C=N Schiff base structural motif as their core moiety. The structure-property relationships of these probes have been investigated. The change of optical properties, caused by different electronic effect and steric effect of the recognition group, has been analyzed systematically. DFT calculation simulation of the Ring-Close and Ring-Open form of all the probes have been employed to illuminate, summarize and confirm these correlations between optical properties and molecular structures. In addition, biological experiment demonstrated that all the probes have a high potential for both sensitive and selective detection, mapping of adsorbed Cu2+ both in vivo and environmental microbial systems. This approach provides a significant strategy for studying structure-property relationships and guiding the synthesis of probes with various optical properties.

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

    DEFF Research Database (Denmark)

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

    compositions by substituting Al2O3 for SiO2. We also investigate the various roles of sodium in the glasses including charge compensation of tetrahedral aluminum and boron atoms and formation of non-bridging oxygen. We find that mechanical properties (density, elastic moduli, and hardness), glass transition...

  8. Atomically resolved tomography to directly inform simulations for structure-property relationships

    Science.gov (United States)

    Moody, Michael P.; Ceguerra, Anna V.; Breen, Andrew J.; Cui, Xiang Yuan; Gault, Baptiste; Stephenson, Leigh T.; Marceau, Ross K. W.; Powles, Rebecca C.; Ringer, Simon P.

    2014-11-01

    Microscopy encompasses a wide variety of forms and scales. So too does the array of simulation techniques developed that correlate to and build upon microstructural information. Nevertheless, a true nexus between microscopy and atomistic simulations is lacking. Atom probe has emerged as a potential means of achieving this goal. Atom probe generates three-dimensional atomistic images in a format almost identical to many atomistic simulations. However, this data is imperfect, preventing input into computational algorithms to predict material properties. Here we describe a methodology to overcome these limitations, based on a hybrid data format, blending atom probe and predictive Monte Carlo simulations. We create atomically complete and lattice-bound models of material specimens. This hybrid data can then be used as direct input into density functional theory simulations to calculate local energetics and elastic properties. This research demonstrates the role that atom probe combined with theoretical approaches can play in modern materials engineering.

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

    Science.gov (United States)

    Tipton, John

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

  10. [Adsorption of Cu on Core-shell Structured Magnetic Particles: Relationship Between Adsorption Performance and Surface Properties].

    Science.gov (United States)

    Li, Qiu-mei; Chen, Jing; Li, Hai-ning; Zhang, Xiao-lei; Zhang, Gao-sheng

    2015-12-01

    In order to reveal the relationship between the adsorption performance of adsorbents and their compositions, structure, and surface properties, the core-shell structured Fe₃O₄/MnO2 and Fe-Mn/Mn₂2 magnetic particles were systematically characterized using multiple techniques and their Cu adsorption behaviors as well as mechanism were also investigated in details. It was found that both Fe₃O4 and Fe-Mn had spinel structure and no obvious crystalline phase change was observed after coating with MnO₂. The introduction of Mn might improve the affinity between the core and the shell, and therefore enhanced the amount and distribution uniformity of the MnO₂ coated. Consequently, Fe-Mn/MnO₂ exhibited a higher BET specific surface area and a lower isoelectric point. The results of sorption experiments showed that Fe-Mn had a higher maximal Cu adsorption capacity of 33.7 mg · g⁻¹ at pH 5.5, compared with 17.5 mg · g⁻¹ of Fe₃O4. After coating, the maximal adsorption capacity of Fe-Mn/MnO₂ was increased to 58.2 mg · g⁻¹, which was 2.6 times as high as that of Fe₃O₄/MnO₂ and outperformed the majority of magnetic adsorbents reported in literature. In addition, a specific adsorption of Cu occurred at the surface of Fe₃O₄/MnO₂ or Fe-Mn/MnO₂ through the formation of inner-sphere complexes. In conclusion, the adsorption performance of the magnetic particles was positively related to their compositions, structure, and surface properties.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  12. Composition-structure-property relationships for non-classical ionomer cements formulated with zinc-boron germanium-based glasses.

    Science.gov (United States)

    Zhang, Xiaofang; Werner-Zwanziger, Ulrike; Boyd, Daniel

    2015-04-01

    Non-classical ionomer glasses like those based on zinc-boron-germanium glasses are of special interest in a variety of medical applications owning to their unique combination of properties and potential therapeutic efficacy. These features may be of particular benefit with respect to the utilization of glass ionomer cements for minimally invasive dental applications such as the atruamatic restorative treatment, but also for expanded clinical applications in orthopedics and oral-maxillofacial surgery. A unique system of zinc-boron-germanium-based glasses (10 compositions in total) has been designed using a Design of Mixtures methodology. In the first instance, ionomer glasses were examined via differential thermal analysis, X-ray diffraction, and (11)B MAS NMR spectroscopy to establish fundamental composition - structure-property relationships for the unique system. Secondly, cements were synthesized based on each glass and handling characteristics (working time, Wt, and setting time, St) and compression strength were quantified to facilitate the development of both experimental and mathematical composition-structure-property relationships for the new ionomer cements. The novel glass ionomer cements were found to provide Wt, St, and compression strength in the range of 48-132 s, 206-602 s, and 16-36 MPa, respectively, depending on the ZnO/GeO2 mol fraction of the glass phase. A lower ZnO mol fraction in the glass phase provides higher glass transition temperature, higher N4 rate, and in combination with careful modulation of GeO2 mol fraction in the glass phase provides a unique approach to extending the Wt and St of glass ionomer cement without compromising (in fact enhancing) compression strength. The data presented in this work provide valuable information for the formulation of alternative glass ionomer cements for applications within and beyond the dental clinic, especially where conventional approaches to modulating working time and strength exhibit co

  13. Structure-property relationship of regenerated spider silk protein nano/microfibrous scaffold fabricated by electrospinning.

    Science.gov (United States)

    Yu, Qiaozhen; Xu, Shuiling; Zhang, Hong; Gu, Li; Xu, Yepei; Ko, Frank

    2014-11-01

    The regenerated Araneus ventricosus spider dragline silk protein fibrous scaffold with moderate strength and flexibility was fabricated by electrospinning and post treatment with 90 vol % acetone. The effect of collection method on the morphology of regenerated spider silk protein (RSSP) fibrous scaffold, the effects of the post treatment solvents and their concentrations on the molecular conformation, crystallinity and mechanical properties were studied. The results show that the morphology was affected by the solvent used in the coagulation bath. The molecular conformation, crystallinity and mechanical property of this scaffold were strongly affected by the kind of post treatment solvent and slightly influenced by its concentration when it was higher than 50 vol %. The degradation rate of this scaffold was very slow and resulting in little pH change of the degradation medium within 5 months. PC 12 cells were cultured on the electrospun RSSP fibrous scaffold and in its extraction fluid to examine the changes of PC 12 cells after different times of culture. The results show that the electrospun RSSP fibrous scaffold had good biocompatibility with PC 12 cells.

  14. 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 (χc 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 χc. 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.

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

    KAUST Repository

    Burkhardt, Stephen E.

    2013-01-22

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

  16. Theoretical perspective of FIrpic derivatives: relationship between structures and photophysical properties

    Science.gov (United States)

    Li, Jieqiong; Wang, Li; Wang, Xin; Zhang, Jinglai; Cui, Xiaofeng; Li, Youwei; Han, Bingkun

    2017-01-01

    The phosphorescent properties of a series of potential blue-emitting Ir(III) complexes (C^N)2Ir(N^N‧) are studied by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). Their possibilities to be blue-emitting phosphors are theoretically evaluated by the electroluminescence (EL) performance and phosphorescence quantum yield. The effect of two different substituents attached on the difluorophenyl ring is explored by comparison of the complexes in groups I (1a-4a) and II (1b-4b). Furthermore, to explore the influence of the stronger electron-donating/withdrawing group substituted on the primary ligand, the properties of complexes 1c and 1d are estimated. All the substituents are added on the para-position of the corresponding ring. The comparable radiative rate constant (kr) and nonradiative rate constant (knr) result in the similar quantum yield for complexes in two groups. Besides, the balance of the reorganization energies for complexes 2b-4b is better than others.

  17. Structure-property relationships in carbon nanotube-polymer systems: Influence of noncovalent stabilization techniques

    Science.gov (United States)

    Liu, Lei

    A variety of experiments were carried out to study the dispersion and microstructure of carbon nanotubes in aqueous suspensions and polymer composites with the goal to improve the electrical conductivity of the composites containing nanotubes. Epoxy composites containing covalently and noncovalently functionalized nanotubes were compared in terms of electrical and mechanical behavior. Covalent functionalization of nanotubes is based on chemical attachments of polyethylenimine (PEI) whereas noncovalent functionalization takes place through physical mixing of nanotubes and PEI. The electrical conductivity is reduced in composites containing covalently functionalized nanotubes due to damage of the tube's conjugated surface that reduces intrinsic conductivity. Conversely, the mechanical properties are always better for epoxy composites containing covalently functionalized nanotubes. Clay particles were used as a rigid dispersing aid for nanotubes in aqueous suspensions and epoxy composites. When both nanotubes and clay were introduced into water by sonication, the suspension is stable for weeks, whereas the nanotubes precipitate almost instantly for the suspension without clay. In epoxy composites, nanotubes form separated clusters of aggregation, whereas a continuous three-dimensional nanotube network is achieved when clay is introduced. Electrical conductivity of the epoxy composite is shown to significantly improve with a small addition of clay and the percolation threshold is simultaneously decreased (from 0.05 wt% nanotubes, when there is no clay, to 0.01 wt% when 2 wt% clay is introduced). The addition of clay can also improve the mechanical properties of the composites, especially at higher clay concentration. Weak polyelectrolytes (i.e., pH-responsive polymers) were also studied for their interaction with nanotubes and the electrical properties of the dried composite films. When dispersed by sonication, Nanotubes show pH-dependent dispersion and stability in

  18. 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 κ-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 β-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

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

    Energy Technology Data Exchange (ETDEWEB)

    Heitfeld, Kevin A.; Schaefer, Dale W.

    2010-10-12

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

  20. 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)

  1. 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 (η0, λ0, 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.

  2. Relationship of granule size distribution and amylopectin structure with pasting, thermal, and retrogradation properties in wheat starch.

    Science.gov (United States)

    Singh, Sandeep; Singh, Narpinder; Isono, Naoto; Noda, Takahiro

    2010-01-27

    Starches separated from 18 Indian wheat varieties were evaluated to see relationship of granule size distribution and amylopectin structure with pasting, thermal, and retrogradation properties. Average diameter of A-, B-, and C-granules among different starches varied between 23.0 and 28.5, 10.0 and 12.0, and 2.3 and 2.7 mum, respectively. Amylopectin chain length distribution varied significantly, short length chains (DP 6-12) and long length chains (DP > 24) ranged between 44.5 and 52.4% and 3.7 and 6.5%, respectively, whereas amylose content ranged between 18.2 and 28.8%. Short length chains of amylopectin had inverse relationship with starch gelatinization temperatures T(o), T(p), and T(c). Starches with higher crystallinity had higher enthalpy of gelatinization and lower swelling power. Paste characteristics were mainly dependent upon granule type and all pasting parameters except pasting temperature, showed significant positive correlations with A-granules and negative with the proportion of B- and C-granule.

  3. Multi-objective Modeling and Assessment of Partition Properties: A GA-Based Quantitative Structure-Property Relationship Approach

    Institute of Scientific and Technical Information of China (English)

    印春生; 刘新会; 郭卫民; 刘树深; 韩朔暌; 王连生

    2003-01-01

    In this work a multi-objective quantitative structure-property relationship (QSPR) analysis approach was reported based on the study on three partition properties of 50 aromatic sulfur-containing carboxylates. Here multi-objectives ( properties )were taken as a vector for QSPR modeling. The quantitative correlations for partition properties were developed using a ge-netic algorithm-based variable-selection approach with quantum descriptors, derived from AM1-based calculations.With the QSPR models, the aqueous solubmty, octanol/water partition coefficients and reversed-phase HPLC capacity factors of sulfur-contalning compounds were estimated and predicted.Using GA-based multivariate linear regression with cross-vali-dation procedure, a set of the most promising descriptors was selegted from a pool of 28 quantum chemical semi-empirical de-scriptors, incloding steric and electronic types, to integrally build QSPR models. The selected molecular descriptors includ-ed the net charges on carboxyl group (Qoc), the 2nd power of net ehnrges on nitrogen atoms (QN2), the net atomic charge on the sulfur atoms (Qs), the van der Waals volume of molecule (V), the most positive net atomic charge on hydrogen atoms(QH) and the measure of polarity and polarizability (π),which were main factors affecting the distribution processes of the compounds under study. The statistically best QSPR models of six descriptors were simultaneously obtained by GA-based linear regression analysis. With the selected descriptors and the QSPR equations, mechanisms of partition action of the Sulfur-containing carboxylates were able to be investigated and inter-preted.

  4. Endochin optimization: structure-activity and structure-property relationship studies of 3-substituted 2-methyl-4(1H)-quinolones with antimalarial activity.

    Science.gov (United States)

    Cross, R Matthew; Monastyrskyi, Andrii; Mutka, Tina S; Burrows, Jeremy N; Kyle, Dennis E; Manetsch, Roman

    2010-10-14

    Since the 1940s endochin and analogues thereof were known to be causal prophylactic and potent erythrocytic stage agents in avian models. Preliminary screening in a current in vitro assay identified several 4(1H)-quinolones with nanomolar EC(50) against erythrocytic stages of multidrug resistant W2 and TM90-C2B isolates of Plasmodium falciparum. Follow-up structure-activity relationship (SAR) studies on 4(1H)-quinolone analogues identified several key features for biological activity. Nevertheless, structure-property relationship (SPR) studies conducted in parallel revealed that 4(1H)-quinolone analogues are limited by poor solubilities and rapid microsomal degradations. To improve the overall efficacy, multiple 4(1H)-quinolone series with varying substituents on the benzenoid quinolone ring and/or the 3-position were synthesized and tested for in vitro antimalarial activity. Several structurally diverse 6-chloro-2-methyl-7-methoxy-4(1H)-quinolones with EC(50) in the low nanomolar range against the clinically relevant isolates W2 and TM90-C2B were identified with improved physicochemical properties while maintaining little to no cross-resistance with atovaquone.

  5. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    Science.gov (United States)

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-09

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

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

    Science.gov (United States)

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

    2008-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Naebe, Minoo; Lin Tong; Wang Xungai [Centre for Material and Fibre Innovation, Deakin University, Geelong, VIC 3217 (Australia); Staiger, Mark P [Department of Mechanical Engineering, University of Canterbury, Christchurch (New Zealand); Dai Liming [Department of Chemical and Materials Engineering, University of Dayton, Dayton, OH 45469 (United States)], E-mail: tong.lin@deakin.edu.au

    2008-07-30

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

  8. Structure-property relationships in Sterculia urens/polyvinyl alcohol electrospun composite nanofibres.

    Science.gov (United States)

    Patra, Niranjan; Martinová, Lenka; Stuchlik, Martin; Černík, Miroslav

    2015-04-20

    Sterculia urens (Gum Karaya) based polyvinyl alcohol (PVA) composite nanofibres have been successfully electrospun after chemical modification of S. urens to increase its solubility. The effect of deacetylated S. urens (DGK) on the morphology, structure, crystallization behaviour and thermal stability was studied for spuned fibres before and after spinning post treatment. An apparent increase in the PVA crystallinity were observed in the PVA-DGK composite nanofibres indicating S. urens induced crystallization of PVA. The pure PVA nanofibre and the nanofibres of PVA-DGK composites were introduced to post electrospinning heat treatment at 150°C for 15 min. The presence of sterculia gum reduced the fibre diameter and distribution of the nanofibres due to the increased stretching of the fibres during spinning. Switching of the thermal behaviour occurs due to post spinning heat treatments.

  9. Process-Structure-Property Relationships for 316L Stainless Steel Fabricated by Additive Manufacturing and Its Implication for Component Engineering

    Science.gov (United States)

    Yang, Nancy; Yee, J.; Zheng, B.; Gaiser, K.; Reynolds, T.; Clemon, L.; Lu, W. Y.; Schoenung, J. M.; Lavernia, E. J.

    2016-12-01

    We investigate the process-structure-property relationships for 316L stainless steel prototyping utilizing 3-D laser engineered net shaping (LENS), a commercial direct energy deposition additive manufacturing process. The study concluded that the resultant physical metallurgy of 3-D LENS 316L prototypes is dictated by the interactive metallurgical reactions, during instantaneous powder feeding/melting, molten metal flow and liquid metal solidification. The study also showed 3-D LENS manufacturing is capable of building high strength and ductile 316L prototypes due to its fine cellular spacing from fast solidification cooling, and the well-fused epitaxial interfaces at metal flow trails and interpass boundaries. However, without further LENS process control and optimization, the deposits are vulnerable to localized hardness variation attributed to heterogeneous microstructure, i.e., the interpass heat-affected zone (HAZ) from repetitive thermal heating during successive layer depositions. Most significantly, the current deposits exhibit anisotropic tensile behavior, i.e., lower strain and/or premature interpass delamination parallel to build direction (axial). This anisotropic behavior is attributed to the presence of interpass HAZ, which coexists with flying feedstock inclusions and porosity from incomplete molten metal fusion. The current observations and findings contribute to the scientific basis for future process control and optimization necessary for material property control and defect mitigation.

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

    Science.gov (United States)

    Panpipat, Worawan; Dong, Mingdong; Xu, Xuebing; Guo, Zheng

    2013-10-01

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

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

    Science.gov (United States)

    Avérous, Luc; Pollet, Eric

    2016-03-01

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

  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

  13. Analyis of structure/property relationships in silkworm (Bombyx mori) and spider dragline (Nephila edulis) silks using Raman spectroscopy.

    Science.gov (United States)

    Sirichaisit, Jutarat; Brookes, Victoria L; Young, Robert J; Vollrath, Fritz

    2003-01-01

    The molecular deformation of both silkworm (Bombyx mori) and spider dragline (Nephila edulis) silks has been studied using a combination of mechanical deformation and Raman spectroscopy. The stress/strain curves for both kinds of silk showed elastic behavior followed by plastic deformation. It was found that both materials have well-defined Raman spectra and that some of the bands in the spectra shift to lower frequency under the action of tensile stress or strain. The band shift was linearly dependent upon stress for both types of silk fiber. This observation provides a unique insight into the effect of tensile deformation upon molecular structure and the relationship between structure and mechanical properties. Two similar bands in the Raman spectra of both types of silk in the region of 1000-1300 cm(-1) had significant identical rates of Raman band shift of about 7 cm(-1)/GPa and 14 cm(-1)/GPa demonstrating the similarity between the silk fibers from two different animals.

  14. Specific catalysis of asparaginyl deamidation by carboxylic acids: kinetic, thermodynamic, and quantitative structure-property relationship analyses.

    Science.gov (United States)

    Connolly, Brian D; Tran, Benjamin; Moore, Jamie M R; Sharma, Vikas K; Kosky, Andrew

    2014-04-07

    Asparaginyl (Asn) deamidation could lead to altered potency, safety, and/or pharmacokinetics of therapeutic protein drugs. In this study, we investigated the effects of several different carboxylic acids on Asn deamidation rates using an IgG1 monoclonal antibody (mAb1*) and a model hexapeptide (peptide1) with the sequence YGKNGG. Thermodynamic analyses of the kinetics data revealed that higher deamidation rates are associated with predominantly more negative ΔS and, to a lesser extent, more positive ΔH. The observed differences in deamidation rates were attributed to the unique ability of each type of carboxylic acid to stabilize the energetically unfavorable transition-state conformations required for imide formation. Quantitative structure property relationship (QSPR) analysis using kinetic data demonstrated that molecular descriptors encoding for the geometric spatial distribution of atomic properties on various carboxylic acids are effective determinants for the deamidation reaction. Specifically, the number of O-O and O-H atom pairs on carboxyl and hydroxyl groups with interatomic distances of 4-5 Å on a carboxylic acid buffer appears to determine the rate of deamidation. Collectively, the results from structural and thermodynamic analyses indicate that carboxylic acids presumably form multiple hydrogen bonds and charge-charge interactions with the relevant deamidation site and provide alignment between the reactive atoms on the side chain and backbone. We propose that carboxylic acids catalyze deamidation by stabilizing a specific, energetically unfavorable transition-state conformation of l-asparaginyl intermediate II that readily facilitates bond formation between the γ-carbonyl carbon and the deprotonated backbone nitrogen for cyclic imide formation.

  15. Prediction on Critical Micelle Concentration of Nonionic Surfactants in Aqueous Solution: Quantitative Structure-Property Relationship Approach

    Institute of Scientific and Technical Information of China (English)

    王正武; 黄东阳; 宫素萍; 李干佐

    2003-01-01

    In order to predict the critical micelle concentration (cmc) of nonionic surfactants in aqueous solution, a quantitative structure-property relationship (QSPR) was found for 77 nonionic surfactants belonging to eight series. The best-regressed model contained four quantum-chemical descriptors, the heat of formation (△H), the molecular dipole moment (D), the energy of the lowest unoccupied molecular orbital (ELUMO) and the energy of the highest occupied molecular orbital (EHOMO) of the surfactant molecule; two constitutional descriptors, the molecular weight of surfactant (M) and the number of oxygen and nitrogen atoms (nON ) of the hydrophilic fragment of surfactant molecule; and one topological descriptor, the Kier & Hall index of zero order (KH0) of the hydrophobic fragment of the surfactant. The established general QSPR between Ig (cmc) and the descriptors produced a relevant coefficient of multiple determination: R2=0.986. When cross terms were considered, the corresponding best model contained five descriptors ELUMO, D,KH0, M and a cross term nON·KH0, Which also produced the same coefficient as the seven-parameter model.

  16. 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.

  17. 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.

  18. Definition of general topological equivalence in protein structures. A procedure involving comparison of properties and relationships through simulated annealing and dynamic programming.

    Science.gov (United States)

    Sali, A; Blundell, T L

    1990-03-20

    A protein is defined as an indexed string of elements at each level in the hierarchy of protein structure: sequence, secondary structure, super-secondary structure, etc. The elements, for example, residues or secondary structure segments such as helices or beta-strands, are associated with a series of properties and can be involved in a number of relationships with other elements. Element-by-element dissimilarity matrices are then computed and used in the alignment procedure based on the sequence alignment algorithm of Needleman & Wunsch, expanded by the simulated annealing technique to take into account relationships as well as properties. The utility of this method for exploring the variability of various aspects of protein structure and for comparing distantly related proteins is demonstrated by multiple alignment of serine proteinases, aspartic proteinase lobes and globins.

  19. An Investigation of the Structure-Property Relationships for High Performance Thermoplastic Matrix, Carbon Fiber Composites with a Tailored Polyimide Interphase

    OpenAIRE

    Gardner, Slade Havelock II

    1998-01-01

    The aqueous suspension prepregging technique was used to fabricate PEEK and PPS matrix composites with polyimide interphases of tailored properties. The structure-property relationships of Ultem-type polyimide and BisP-BTDA polyimide which were made from various water soluble polyamic acid salts were studied. The molecular weight of the polyimides was shown to be dependant upon the selection of the base used for making the polyamic acid salt. The development of an Ultem-type polyimide with...

  20. A multi-scale point of view on the structure-property relationships of A15 superconductors

    Institute of Scientific and Technical Information of China (English)

    Yanlong Ding; Min Pan; Shuiquan Deng; Yong Zhao

    2014-01-01

    Nb3Sn and other A15 members have been widely applied in nuclear power, nuclear magnetic reso-nance, and high-energy particle accelerators for their high critical current density (Jc) and upper critical field (Bc2). There have been comprehensive and intensive studies on the applications, the fundamental lattice dynamic and electronic properties, etc., of A15 superconductors. Various reviews on the preparations, structures, and properties have already been written in the last few years. Nevertheless, on account of the large amount of existing facts and views, a coherent view on the relations between the structures and properties has not appeared to unify the facts. This article sketches a multi-scale point of view on the relations between the multi-scale structures and the corresponding properties.

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

    NARCIS (Netherlands)

    Blaazer, A.R.; Lange, J.H.M.; van der Neut, M.A.W.; Mulder, A.; den Boon, F.S.; Werkman, T.R.; Kruse, C.G.; Wadman, W.J.

    2011-01-01

    The discovery, synthesis and structure-activity relationship (SAR) of a novel series of cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptor ligands are reported. Based on the aminoalkylindole class of cannabinoid receptor agonists, a biphenyl moiety was introduced as novel lipophilic indole 3-acyl

  2. Navigating Organo-Lead Halide Perovskite Phase Space via Nucleation Kinetics toward a Deeper Understanding of Perovskite Phase Transformations and Structure-Property Relationships.

    Science.gov (United States)

    Williams, Spencer T; Chueh, Chu-Chen; Jen, Alex K-Y

    2015-07-01

    Organo-lead halide perovskite photovoltaics have developed faster than our understanding of the material itself. Using the vast body of work on perovskite processing created in just the past few years, it is possible to create a better picture of this material's complex phase-transformation behavior. This concept paper summarizes and correlates the current understanding of structural intermediates, kinetic controls, and structure-property relationships of organo-lead iodide perovskites. To this end, a new way of graphically relating information is developed, allowing the simultaneous mapping of schematic kinetic relationships between all currently prevailing perovskite deposition and growth techniques.

  3. Shedding Light on Structure-Property Relationships for Conjugated Microporous Polymers: The Importance of Rings and Strain.

    Science.gov (United States)

    Zwijnenburg, Martijn A; Cheng, Ge; McDonald, Tom O; Jelfs, Kim E; Jiang, Jia-Xing; Ren, Shijie; Hasell, Tom; Blanc, Frédéric; Cooper, Andrew I; Adams, Dave J

    2013-10-08

    The photophysical properties of insoluble porous pyrene networks, which are central to their function, differ strongly from those of analogous soluble linear and branched polymers and dendrimers. This can be rationalized by the presence of strained closed rings in the networks. A combined experimental and computational approach was used to obtain atomic scale insight into the structure of amorphous conjugated microporous polymers. The optical absorption and fluorescence spectra of a series of pyrene-based materials were compared with theoretical time-dependent density functional theory predictions for model clusters. Comparison of computation and experiment sheds light on the probable structural chromophores in the various materials.

  4. Optimization of 1,2,3,4-tetrahydroacridin-9(10H)-ones as antimalarials utilizing structure-activity and structure-property relationships.

    Science.gov (United States)

    Cross, R Matthew; Maignan, Jordany R; Mutka, Tina S; Luong, Lisa; Sargent, Justin; Kyle, Dennis E; Manetsch, Roman

    2011-07-14

    Antimalarial activity of 1,2,3,4-tetrahydroacridin-9(10H)-ones (THAs) has been known since the 1940s and has garnered more attention with the development of the acridinedione floxacrine (1) in the 1970s and analogues thereof such as WR 243251 (2a) in the 1990s. These compounds failed just prior to clinical development because of suboptimal activity, poor solubility, and rapid induction of parasite resistance. Moreover, detailed structure-activity relationship (SAR) studies of the THA core scaffold were lacking and SPR studies were nonexistent. To improve upon initial findings, several series of 1,2,3,4-tetrahydroacridin-9(10H)-ones were synthesized and tested in a systematic fashion, examining each compound for antimalarial activity, solubility, and permeability. Furthermore, a select set of compounds was chosen for microsomal stability testing to identify physicochemical liabilities of the THA scaffold. Several potent compounds (EC(50) < 100 nM) were identified to be active against the clinically relevant isolates W2 and TM90-C2B while possessing good physicochemical properties and little to no cross-resistance.

  5. Relationship between structural and dynamic properties of Al-rich Al-Cu melts: Beyond the Stokes-Einstein relation

    Science.gov (United States)

    Jakse, N.; Pasturel, A.

    2016-12-01

    We perform ab initio molecular dynamics simulations to study structural and transport properties in liquid A l1 -xC ux alloys, with copper composition x ≤0.4 , in relation to the applicability of the Stokes-Einstein (SE) equation in these melts. To begin, we find that self-diffusion coefficients and viscosity are composition dependent, while their temperature dependence follows an Arrhenius-type behavior, except for x =0.4 at low temperature. Then, we find that the applicability of the SE equation is also composition dependent, and its breakdown in the liquid regime above the liquidus temperature can be related to different local ordering around each species. In this case, we emphasize the difficulty of extracting effective atomic radii from interatomic distances found in liquid phases, but we see a clear correlation between transport properties and local ordering described through the structural entropy approximated by the two-body contribution. We use these findings to reformulate the SE equation within the framework of Rosenfeld's scaling law in terms of partial structural entropies, and we demonstrate that the breakdown of the SE relation can be related to their temperature dependence. Finally, we also use this framework to derive a simple relation between the ratio of the self-diffusivities of the components and the ratio of their partial structural entropies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Hao [Materials Sci and Tech Applications, LLC, 409 Maple Springs Drive, Dayton OH 45458 (United States)]. E-mail: hao.jiang@wpafb.af.mil; Hong Lianggou [Materials Sci and Tech Applications, LLC, 409 Maple Springs Drive, Dayton OH 45458 (United States); Venkatasubramanian, N. [Research Institute, University of Dayton, 300 College Park, Dayton, OH 45469-0168 (United States); Grant, John T. [Research Institute, University of Dayton, 300 College Park, Dayton, OH 45469-0168 (United States); Eyink, Kurt [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States); Wiacek, Kevin [Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Wright-Patterson Air Force Base, OH 45433-7251 (United States); Fries-Carr, Sandra [Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Wright-Patterson Air Force Base, OH 45433-7251 (United States); Enlow, Jesse [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States); Bunning, Timothy J. [Air Force Research Laboratory, Materials Directorate, 3005 Hobson Way, Wright-Patterson Air Force Base, OH 45433-7707 (United States)

    2007-02-26

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

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

    Science.gov (United States)

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

    2015-05-11

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

  8. Structure and property of metal melt Ⅲ—Relationship between kinematic viscosity and size of atomic clusters

    Institute of Scientific and Technical Information of China (English)

    POPEL; P; S; KONSTANTINOVA; N; Yu

    2010-01-01

    The method of crucible rotating oscillation damping was employed to measure the kinematic viscosity of aluminum melt,and the curve of viscosity v versus temperature T from 935 to 1383 K was obtained.Besides,based on the calculation model of the evolution behavior of atomic clusters in liquid structure,the curve of atomic clusters size d versus temperature was obtained,and the calculated results are in good agreement with the experimental values.By analyzing experimental data,it was found that both the viscosity and the size of atomic clusters of aluminum melt are monodrome functions of temperature,and the relation between v(T) and d(T) is a linear function,i.e.,v = v 0 + K·d(T).This relation indirectly verifies the calculation model of the structural information of metal melt,which is of great significance for studying the relation between melt microstructure and macro-physical properties.

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

  10. The Relationship Between Star-formation Activity and Galaxy Structural Properties in CANDELS and a Semi-analytic Model

    CERN Document Server

    Brennan, Ryan; Somerville, Rachel S; Barro, Guillermo; Bluck, Asa F L; Taylor, Edward N; Wuyts, Stijn; Bell, Eric F; Dekel, Avishai; Faber, Sandra; Ferguson, Henry C; Koekemoer, Anton M; Kurczynski, Peter; McIntosh, Daniel H; Newman, Jeffrey A; Primack, Joel

    2016-01-01

    We study the correlation of galaxy structural properties with their location relative to the SFR-M* correlation, also known as the star formation "main sequence" (SFMS), in the CANDELS and GAMA surveys and in a semi-analytic model (SAM) of galaxy formation. We first study the distribution of median Sersic index, effective radius, star formation rate (SFR) density and stellar mass density in the SFR-M* plane. We then define a redshift dependent main sequence and examine the medians of these quantities as a function of distance from this main sequence, both above (higher SFRs) and below (lower SFRs). Finally, we examine the distributions of distance from the main sequence in bins of these quantities. We find strong correlations between all of these galaxy structural properties and the distance from the SFMS, such that as we move from galaxies above the SFMS to those below it, we see a nearly monotonic trend towards higher median Sersic index, smaller radius, lower SFR density, and higher stellar density. In the...

  11. 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

  12. Solution structure of a methionine-rich 2S albumin from sunflower seeds: relationship to its allergenic and emulsifying properties.

    Science.gov (United States)

    Pantoja-Uceda, David; Shewry, Peter R; Bruix, Marta; Tatham, Arthur S; Santoro, Jorge; Rico, Manuel

    2004-06-01

    The three-dimensional structure in aqueous solution of SFA-8, a 2S albumin 103-residue protein from seeds of sunflower (Helianthus anuus L.), has been determined by NMR methods. An almost complete (1)H resonance assignment was accomplished from analysis of two-dimensional (2D) COSY and 2D TOCSY spectra, and the structure was computed by using restrained molecular dynamics on the basis of 1393 upper limit distance constraints derived from NOE cross-correlation intensities measured in 2D NOESY spectra. In contrast with most other 2S albumins, SFA-8 consists of a single polypeptide chain without any cleavage in the segment of residues 30-46. The computed structures exhibited an rmsd radius of 0.52 A for the backbone structural core (residues 11-30 and 46-101) and 1.01 A for the side chain heavy atoms. The resulting structure consists of five amphipathic helices arranged in a right-handed superhelix, a folding motif first observed in nonspecific lipid transfer (nsLTP) proteins, and common to other 2S albumins. In contrast to nsLTP proteins, neither SFA-8 nor RicC3 (a 2S albumin from castor bean) has an internal cavity that is able to host a lipid molecule, which results from an exchange in the pairing of disulfide bridges in the CXC segment. Both 2S albumins and nonspecific lipid transfer proteins belong to the prolamin superfamily, which includes a number of important food allergens. Differences in the extension and solvent exposition of the so-called "hypervariable loop" (which connects helices III and IV) in SFA-8 and RicC3 may be responsible for the different allergenic properties of the two proteins. SFA-8 has been shown to form highly stable emulsions with oil/water mixtures. We propose that these properties may be determined partly by a hydrophobic patch at the surface of the protein which consists of five methionines that partially hide the Trp76 residue. The flexibility of the loop which contains Trp76 and the hydrophobicity of the whole environment may favor

  13. Exploring functional relationships between post-fire soil water repellency, soil structure and physico-chemical properties

    Science.gov (United States)

    Quarfeld, Jamie; Brook, Anna; Keestra, Saskia; Wittenberg, Lea

    2016-04-01

    Soil water repellency (WR) and aggregate stability (AS) are two soil properties that are typically modified after burning and impose significant influence on subsequent hydrological and geomorphological dynamics. The response of AS and soil WR to fire depends upon how fire has influenced other key soil properties (e.g. soil OM, mineralogy). Meanwhile, routine thinning of trees and woody vegetation may alter soil properties (e.g. structure and porosity, wettability) by use of heavy machinery and species selection. The study area is situated along a north-facing slope of Mount Carmel national park (Israel). The selected sites are presented as a continuum of management intensity and fire histories. To date, the natural baseline of soil WR has yet to be thoroughly assessed and must be investigated alongside associated soil aggregating parameters in order to understand its overall impact. This study examines (i) the natural baseline of soil WR and physical properties compared to those of disturbed sites in the immediate (controlled burn) and long-term (10-years), and (ii) the interactions of soil properties with different control factors (management, surface cover, seasonal-temporal, burn temperature, soil organic carbon (OC) and mineralogy) in Mediterranean calcareous soils. Analysis of surface soil samples before and after destruction of WR by heating (200-600°C) was implemented using a combination of traditional methods and infrared (IR) spectroscopy. Management and surface cover type conditioned the wettability, soil structure and porosity of soils in the field, although this largely did not affect the heat-induced changes observed in the lab. A positive correlation was observed along an increasing temperature gradient, with relative maxima of MWD and BD reached by most soils at the threshold of 400-500°C. Preliminary analyses of soil OC (MIR) and mineralogical composition (VIS-NIR) support existing research regarding: (i) the importance of soil OC quality and

  14. STRUCTURE-PROPERTY RELATIONSHIP OF POLYELECTROLYTES AND ITS APPLICATION IN STABILIZING DRILLING-MUD IN PRESENCE OF SALTS

    Institute of Scientific and Technical Information of China (English)

    LI Zhuomei; ZHANG Xuexin; XIE Zhiming; HUANG Yuhui

    1990-01-01

    A new polyelectrolyte (SPU) has been prepared. It can depress the water-loss of drilling-mud much more effective than the commonly used acrylic polyelectrolytes even in 30% NaCl solution.SPU has phenyl group in the backbone with -SO3- in the side chain while the acrylic polyelectrolytes have C- C and -COO- respectively. there exists an intrinsic relationship between the structure of polymer and its tolerance to salts. It has been found: 1 ) The adsorption amount of polymer on clay is related closely to the flexibility of polymer chain. 2) The salt-tolerance of -SO3-is superior to -COO-. 3) Both SPU-mud and HPAN-mud are plastic fluids. The dependence of yield point on salts relates to the molecular weight of polymer and hydration of ionogenic group,which is quite different for SPU-mud and HPAN-mud. 4) The extent of raising zeta-potential of base-mud by SPU is greater than by HPAN, but the extent of dropping zeta-potential of SPU-mud by NaCl is smaller than HPAN-mud. According to these results we suppose the salt-tolerance of SPU-mud is attributed mainly to hydration of -SO3- and that of HPAN-mud mainly to network structure formed in the drilling-mud.

  15. Structure-Property Relationship of Cu-Al-Ni-Fe Shape Memory Alloys in Different Quenching Media

    Science.gov (United States)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Farahany, S.

    2014-01-01

    This paper presents the effects of heat treatments using various quenching media on the phase transformation parameters and microstructure parameters. The effects of different quenching methods, step-quenched and up-quenched, in various media were evaluated by using differential scanning calorimetry, field emission electron microscopy, energy-dispersive spectrometry, atomic force microscopy, x-ray diffraction, and Vicker's hardness. The variations of the structure and properties of Cu-Al-Ni-Fe shape memory alloys were linked to the variations of morphology, type, and stabilization of the obtained phase. From the DSC results, the use of ice water as a quenching medium produced the highest transformation temperatures, while a brine solution-quenching medium resulted in the highest change of the entropy and enthalpy. Additionally, it was found that the best grain refinement was observed through the use of an oil-quenching medium, due to its high cooling rate.

  16. Metal-free organic dyes for dye-sensitized solar cells: from structure: property relationships to design rules.

    Science.gov (United States)

    Mishra, Amaresh; Fischer, Markus K R; Bäuerle, Peter

    2009-01-01

    Dye-sensitized solar cells (DSSC) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy. This Review focuses on recent advances in molecular design and technological aspects of metal-free organic dyes for applications in dye-sensitized solar cells. Special attention has been paid to the design principles of these dyes and on the effect of various electrolyte systems. Cosensitization, an emerging technique to extend the absorption range, is also discussed as a way to improve the performance of the device. In addition, we report on inverted dyes for photocathodes, which constitutes a relatively new approach for the production of tandem cells. Special consideration has been paid to the correlation between the molecular structure and physical properties to their performance in DSSCs.

  17. The relationship between star formation activity and galaxy structural properties in CANDELS and a semi-analytic model

    Science.gov (United States)

    Brennan, Ryan; Pandya, Viraj; Somerville, Rachel S.; Barro, Guillermo; Bluck, Asa F. L.; Taylor, Edward N.; Wuyts, Stijn; Bell, Eric F.; Dekel, Avishai; Faber, Sandra; Ferguson, Henry C.; Koekemoer, Anton M.; Kurczynski, Peter; McIntosh, Daniel H.; Newman, Jeffrey A.; Primack, Joel

    2017-02-01

    We study the correlation of galaxy structural properties with their location relative to the SFR-M* correlation, also known as the star formation `star-forming main sequence' (SFMS), in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and Galaxy and Mass Assembly Survey and in a semi-analytic model (SAM) of galaxy formation. We first study the distribution of median Sérsic index, effective radius, star formation rate (SFR) density and stellar mass density in the SFR-M* plane. We then define a redshift-dependent main sequence and examine the medians of these quantities as a function of distance from this main sequence, both above (higher SFRs) and below (lower SFRs). Finally, we examine the distributions of distance from the main sequence in bins of these quantities. We find strong correlations between all of these galaxy structural properties and the distance from the SFMS, such that as we move from galaxies above the SFMS to those below it, we see a nearly monotonic trend towards higher median Sérsic index, smaller radius, lower SFR density, and higher stellar density. In the SAM, bulge growth is driven by mergers and disc instabilities, and is accompanied by the growth of a supermassive black hole which can regulate or quench star formation via active galactic nucleus feedback. We find that our model qualitatively reproduces the trends described above, supporting a picture in which black holes and bulges co-evolve, and active galactic nucleus feedback plays a critical role in moving galaxies off of the SFMS.

  18. 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 matrix fibers. These results suggest that subcutaneous AT has greater capacity for expansion and recovery from mechanical deformation than omental AT.

  19. 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.

  20. Effect of Fe(3)O(4) on the sedimentation and structure-property relationship of starch under different pHs.

    Science.gov (United States)

    Palanikumar, S; Siva, P; Meenarathi, B; Kannammal, L; Anbarasan, R

    2014-06-01

    The nanosized ferrite (Fe3O4) was synthesized and characterized by analytical techniques such as Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy, fluorescence spectroscopy and transmission electron microscopy (TEM). The structure-property relationship of starch was studied under three different pHs namely 3.8, 7.1 and 12.5. The starch treated under acidic condition was degraded. In a similar manner, the structure-property relationship of starch in the presence of ferrite nanoparticles at three different pHs, as mentioned above was studied. The starch/ferrite nanocomposite prepared under acidic condition showed a degraded structure. Further, the polymer/nanocomposite systems were characterized by analytical techniques such as FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vibrating sample measurement (VSM), TEM and scanning electron microscopy (SEM). Finally, the settling velocity of starch under three different pHs both in the presence and absence of Fe3O4 was carried out to ensure the role of pH and effect of Fe3O4 on the settling velocity of starch.

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

    Science.gov (United States)

    Gao, Jia-Suo; Tong, Xu-Peng; Chang, Yi-Qun; He, Yu-Xuan; Mei, Yu-Dan; Tan, Pei-Hong; Guo, Jia-Liang; Liao, Guo-Chao; Xiao, Gao-Keng; Chen, Wei-Min; Zhou, Shu-Feng; Sun, Ping-Hua

    2015-01-01

    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 q (2) values of 0.753 and 0.770, and r (2) 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.

  2. 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.

  3. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO2 Adsorption.

    Science.gov (United States)

    Pham, Trong D; Hudson, Matthew R; Brown, Craig M; Lobo, Raul F

    2017-03-09

    The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst ) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol(-1) ). Mg(2+) was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2 , leading to a much lower Qst (ca. 30 kJ mol(-1) ) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li(+) and Mg(2+) cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2 .

  4. Structure-Processing-Property Relationship of Poly(Glycolic Acid for Drug Delivery Systems 1: Synthesis and Catalysis

    Directory of Open Access Journals (Sweden)

    Vineet Singh

    2010-01-01

    Full Text Available Till date, market is augmented with a huge number of improved drug delivery systems. The success in this area is basically due to biodegradable polymers. Although conventional systems of drug delivery utilizing the natural and semisynthetic polymers so long but synthetic polymer gains success in the controlled drug delivery area due to better degradation profile and controlled network and functionality. The polyesters are the most studied class group due the susceptible ester linkage in their backbone. The Poly(glycolic Acid (PGA, Poly(lactic acid (PLA, and Polylactide-co-glycolide (PLGA are the best profiled polyesters and are most widely used in marketed products. These polymers, however, still are having drawbacks which failed them to be used in platform technologies like matrix systems, microspheres, and nanospheres in some cases. The common problems arose with these polymers are entrapment inefficiency, inability to degrade and release drugs with required profile, and drug instability in the microenvironment of the polymers. These problems are forcing us to develop new polymers with improved physicochemical properties. The present review gave us an insight in the various structural elements of Poly(glycolic acid, polyester, with in depth study. The first part of the review focuses on the result of studies related to synthetic methodologies and catalysts being utilized to synthesize the polyesters. However the author will also focus on the effect of processing methodologies but due some constraints those are not included in the preview of this part of review.

  5. 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.

  6. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Trong D. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Hudson, Matthew R. [Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Brown, Craig M. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA; Lobo, Raul F. [Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA

    2017-02-16

    The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol-1). Mg2+ was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2, leading to a much lower Qst (ca. 30 kJ mol-1) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li+ and Mg2+ cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2.

  7. Classification of carbon materials for developing structure-properties relationships based on the aggregate state of the precursors

    Institute of Scientific and Technical Information of China (English)

    Oleksiy V. Khavryuchenko; Volodymyr D.Khavryuchenko

    2014-01-01

    Modern carbon science lacks an efficient structure-related classi-fication of materials. We present an approach based on dividing carbon materials by the aggregate state of the precursor. The common features in the structure of carbon particles that allow putting them into a group are discussed, with particular attention to the potential energy stored in the carbon structure from differ-ent rates of relaxation during the synthesis and prearrangement of structural motifs due to the effect of the precursor structure.

  8. Notes on quantitative structure-property relationships (QSPR), part 3: density functions origin shift as a source of quantum QSPR algorithms in molecular spaces.

    Science.gov (United States)

    Carbó-Dorca, Ramon

    2013-04-05

    A general algorithm implementing a useful variant of quantum quantitative structure-property relationships (QQSPR) theory is described. Based on quantum similarity framework and previous theoretical developments on the subject, the present QQSPR procedure relies on the possibility to perform geometrical origin shifts over molecular density function sets. In this way, molecular collections attached to known properties can be easily used over other quantum mechanically well-described molecular structures for the estimation of their unknown property values. The proposed procedure takes quantum mechanical expectation value as provider of causal relation background and overcomes the dimensionality paradox, which haunts classical descriptor space QSPR. Also, contrarily to classical procedures, which are also attached to heavy statistical gear, the present QQSPR approach might use a geometrical assessment only or just some simple statistical outline or both. From an applied point of view, several easily reachable computational levels can be set up. A Fortran 95 program: QQSPR-n is described with two versions, which might be downloaded from a dedicated web site. Various practical examples are provided, yielding excellent results. Finally, it is also shown that an equivalent molecular space classical QSPR formalism can be easily developed.

  9. Azadipyrromethene dye derivatives in coordination chemistry: the structure-property relationship in homoleptic metal(II) complexes.

    Science.gov (United States)

    Bessette, André; Ferreira, Janaina G; Giguère, Martin; Bélanger, Francis; Désilets, Denis; Hanan, Garry S

    2012-11-19

    As a chromophore closely related to dipyrromethene (DPM), the azadipyrromethene (ADPM) family has attracted much interest in the life sciences and optoelectronic fields. A high-yielding microwave-assisted synthesis is reported for new homoleptic complexes of cobalt(II), nickel(II), copper(II) and zinc(II) based on the tetrakis(p-methoxyphenyl)azadipyrromethene ligand 1b. These complexes are compared with other homoleptic complexes of the same metal(II) series based on the tetraphenylazadipyrromethene 1a and also with related BF2(+) chelates (Aza-BODIPYs 6a and 6b) for a better understanding of trends arising from substitution of the chelate and/or the electron-donating effect of the p-methoxy substituents. The electrochemical behavior of the new compounds 2b, 3b, and 5b in dichloromethane revealed two pseudoreversible reductions (2b, -1.09 and -1.25 V vs SCE; 3b, -1.05 and -1.29 V; 5b, -1.13 and -1.25 V) followed by a third irreversible process (2b, -1.78 V; 3b, -1.80 V; 5b, -1.77 V) along with two pseudoreversible oxidations (2b, 0.55 and 0.80 V; 3b, 0.56 and 0.80 V; 5b, 0.55 and 0.80 V) followed by two closely spaced irreversible processes (2b, 1.21 and 1.27 V; 3b, 1.21 and 1.28 V; 5b, 1.22 and 1.25 V). On its side, copper(II) homoleptic complex 4b revealed only one pseudoreversible reduction at -0.59 V followed by three irreversible processes at -0.95, -1.54, and -1.74 V, respectively. The oxidation behavior of this complex exhibited two pseudoreversible processes (0.55 and 0.82 V) and two irreversible processes (1.19 and 1.25 V). The redox processes are assigned and discussed in relation to their photophysical properties. X-ray structures for 1b and related copper(II) complex 2b are also discussed.

  10. Synthesis of novel strontium-based cuprate superconducting thin films, and the relationship between their crystal structures and electrical properties

    Science.gov (United States)

    Chang, Kuo-Wei

    2000-12-01

    Novel Sr-based cuprate thin films were investigated to explore their potential as next generation superconducting materials. Thin films of infinite-layer compound (Sr,Ca)CuO2 (no blocking layer), cuprate oxycarbonate Sr2CuO2(CO3) (carbonate blocking layer), and Tl(Sr,Ba)2Can-1CunOy (n = 2 and 3) (thin blocking layer) were synthesized using metal-organic chemical vapor deposition. The structure and defect chemistry of the blocking layers of these cuprate compounds were found to have profound effects on the transport properties both in the normal state and the superconducting state. Phase pure, epitaxial infinite-layer compound (Sr1-xCa x)CuO2 thin films were deposited on SrTiO3(100) substrates. However, these films were always semiconducting with resistivities of the order of 1 ohm- cm and with carrier concentrations of 1017~10 19cm-3, which is two to four orders of magnitude lower than the typical superconducting cuprates. The low carrier concentration was attributed to the absence of blocking layers containing a sufficient concentration of charged defects. Transport was via variable range hopping conduction. By annealing in air, the infinite-layer compound SrCuO2 thin films reacted with the CO2 in air to generate Sr 2CuO2(CO3) thin films. Upon formation of carbonate blocking layers, charger carriers were introduced into the Sr2CuO 2(CO3) thin films through the partial substitution of carbon by copper or boron in the SrCO3 blocking layers. After oxygen annealing or upon boron substitution, the carrier concentration increased up to 10 21 cm-3. A superconducting onset temperature of 34K and a zero resistivity temperature of 20K have been observed for Sr 2CuO2(C1-xBx)O3 thin films. A critical carrier density of 0.10~0.12 holes/Cu was required to render superconductivity. The effect of crystal structure on the critical current density was investigated by measuring the vortex pinning energies of Tl2Ba2CaCu 2Oy (Tl-2212) and Tl(Sr,Ba)2Ca Cu2O y (Tl- (Sr,Ba)1212) thin

  11. On the Development and Use of Large Chemical Similarity Networks, Informatics Best Practices and Novel Chemical Descriptors Towards Materials Quantitative Structure Property Relationships

    Science.gov (United States)

    Krein, Michael

    After decades of development and use in a variety of application areas, Quantitative Structure Property Relationships (QSPRs) and related descriptor-based statistical learning methods have achieved a level of infamy due to their misuse. The field is rife with past examples of overtrained models, overoptimistic performance assessment, and outright cheating in the form of explicitly removing data to fit models. These actions do not serve the community well, nor are they beneficial to future predictions based on established models. In practice, in order to select combinations of descriptors and machine learning methods that might work best, one must consider the nature and size of the training and test datasets, be aware of existing hypotheses about the data, and resist the temptation to bias structure representation and modeling to explicitly fit the hypotheses. The definition and application of these best practices is important for obtaining actionable modeling outcomes, and for setting user expectations of modeling accuracy when predicting the endpoint values of unknowns. A wide variety of statistical learning approaches, descriptor types, and model validation strategies are explored herein, with the goals of helping end users understand the factors involved in creating and using QSPR models effectively, and to better understand relationships within the data, especially by looking at the problem space from multiple perspectives. Molecular relationships are commonly envisioned in a continuous high-dimensional space of numerical descriptors, referred to as chemistry space. Descriptor and similarity metric choice influence the partitioning of this space into regions corresponding to local structural similarity. These regions, known as domains of applicability, are most likely to be successfully modeled by a QSPR. In Chapter 2, the network topology and scaling relationships of several chemistry spaces are thoroughly investigated. Chemistry spaces studied include the

  12. 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)χ), 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Peng [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China) and College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China)], E-mail: ggootc@163.com; Tian Feifei [College of Bioengineering, Chongqing University, Chongqing 400044 (China); Li Zhiliang [College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044 (China) and State Key Laboratory of Chemo/Biosensing and Chemometrics, Changsha 410082 (China)], E-mail: ggootc@163.com

    2007-08-10

    Aiming at ion mobility spectrometry (IMS), computer-assisted ion mobility prediction (CAIMP) has been recently developed to simulate and predict diverse IMS behaviors in assistance of mathematics and computer science. Of that, quantitative structure-property relationship (QSPR) plays a vital role, dedicating to predict properties of unknown samples by creating statistical model based on known samples. In QSPR, the key lies in how to transform structural characteristics of target compounds into a group of numerical codes. In consideration that future IMS applications may mainly focus on intricate drug/biological systems, a novel molecular structural characterization method referring to molecular graphic fingerprint (MoGF) is proposed in this paper. In MoGF approach, radical distribution function is employed to map intrinsic interatomic correlations into a coordinate system according to a reasonable sampling interval, thus forming the characteristic graph curve which is rich in information on molecular structural characteristics, possessing of great merits in easy calculation, independent of experiments, large information contents, explicit structural meanings and intuitive expressions, etc. Consequently, MoGF is utilized to QSPR studies on 579 singly protonated peptide collision cross sections, and the constructed partial least square (PLS) regression model is confirmed to be robust and predictable by rigorous both internal and external validations, with statistics as r{sup 2} = 0.991, q{sup 2} = 0.990, RMSEE = 5.526, RMSCV = 5.572, q{sub ext}{sup 2}=0.990, r{sub ext}{sup 2}=0.990, r{sub 0,ext}{sup 2}=0.990, r{sub 0,ext}{sup '2}=0.990, k = 1.003, k' = 0.996 and RMSEP = 5.561, respectively.

  14. 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

    2015-05-07

    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

  15. 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 α/β 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 α/β 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 β8 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.

  16. 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 (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 (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.

  17. Structure-property relationships of solid polymeric catalysts: isopropanol dehydration to propylene catalyzed by sulfonated polyethylene-grafted styrene

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C.A.

    1979-01-01

    Isopropanol dehydration to propylene catalyzed by sulfonated polyethylene-grafted styrene was used to measure the effects on the catalytic activity of structural charges induced in the membranes by constant-rate, cold drawing by 75, 150, and 200 3< of their initial lengths. The form of the rate expression for the reaction with undrawn and drawn membranes at 100/sup 0/C and 1 atm under differential reaction conditions was the same and could be explained by a concerted reaction mechanism involving intermediate isopropanol hydrogen bonded to about four -SO/sub 3/H groups. The maximum reaction rate (based on catalyst acidity) increased by approx. 80% from the undrawn membrane to the 150% drawn membrane and then decreased by approx. 70% from the maximum observed for the 150% drawn membrane to the 200% drawn membrane. A structural model was developed on the basis that the -SO/sub 3/H groups are confined to the amorphous phase due to steric exclusion but that they redistribute to more favorable arrangements during drawing. Model predictions were supported by X-ray and birefringence studies.

  18. Variable range hopping in single-wall carbon nanotube thin films: a processing-structure-property relationship study.

    Science.gov (United States)

    Luo, Sida; Liu, Tao; Benjamin, Shermane M; Brooks, James S

    2013-07-09

    By varying the ultrasonication and ultracentrifugation conditions, single-walled carbon nanotube (SWCNT) dispersions with a broad range of SWCNT length and diameter (L = 342-3330 nm; d = 0.5-12 nm) were prepared and characterized by a preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) technique. The well-characterized dispersions were then fabricated into SWCNT thin films by spray coating. Combined optical, spectroscopic, and temperature-dependent electrical measurements were performed to study the effect of SWCNT structures on the charge transport behavior of SWCNT thin films. Regardless of SWCNT size in the dispersion and the thin film thickness, the three-dimensional variable range hopping (3D VRH) conduction model was found to be appropriate in explaining the temperature-dependent sheet resistance results for all SWCNT thin films prepared in this study. More importantly, with the SWCNT structural information determined by the PUM method, we were able to identify a strong correlation between the length of SWCNTs and the 3D VRH parameter T0, the Mott characteristic temperature. When the SWCNT length is less than ∼700 nm, the T0 of SWCNT thin films shows a drastic increase, but when the length is greater than ~700 nm, T0 is only weakly dependent on the SWCNT length. Under the framework of traditional VRH, we further conclude that the electron localization length of SWCNT thin films shows a similar dependence on the SWCNT length.

  19. Relationship between structural and magnetic properties in (Ti,Fe)O{sub 2} powders obtained by mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Mudarra Navarro, A.M. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, IFLP-CCT La Plata-CONICET (Argentina); Bilovol, V. [LSA-INTECIN-CONICET, Facultad de Ingenieria, Universidad Nacional de Buenos Aires (Argentina); Cabrera, A.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, IFLP-CCT La Plata-CONICET (Argentina); Rodriguez Torres, C.E., E-mail: torres@fisica.unlp.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, IFLP-CCT La Plata-CONICET (Argentina)

    2012-08-15

    Fe-doped TiO{sub 2} samples with different Fe content were prepared by mechanical alloying starting from TiO{sub 2} rutile and FeO. The samples were structurally and magnetically characterized by XRD, Moessbauer spectroscopy, X-ray absorption spectroscopy (XAS), AC-susceptibility and magnetization measurements. XAS results showed that Fe ions were incorporated into the rutile phase with oxygen coordination that was lower than that expected in this phase. The oxygen coordination number decreased with the increase of Fe{sup 2+} ions such as it was previously found in the milled samples of TiO{sub 2} doped with hematite. The RT Moessbauer spectra were reproduced using two paramagnetic interactions, one corresponding to Fe{sup 2+} ({delta}{approx}0.87 mm/s) and the other to Fe{sup 3+} ({delta}{approx}0.31 mm/s). Magnetometry measurements showed the presence of paramagnetic and ferromagnetic-like interactions at room temperature. Although saturation and coercivity of the ferromagnetic phase increased with iron, the effective magnetic moment per iron atom decreased, probably due to the precipitation of Fe rich antiferromagnetic structures.

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Structure activity relationships of spiramycins.

    Science.gov (United States)

    Omura, S; Sano, H; Sunazuka, T

    1985-07-01

    Sixty-six derivatives of spiramycin I and neospiramycin I were synthesized and evaluated by four parameters, MIC, affinity to ribosomes (ID50), therapeutic effect in mice and retention time in HPLC. Among the derivatives, 3,3'',4''-tri-O-propionyl- and 3,4''-di-O-acetyl-3''-O-butyrylspiramycin I showed the highest therapeutic effect which was superior to acetylspiramycin. Structure activity relationships of spiramycins are discussed.

  3. Differentiation between stoichiometric and anticatalytic antioxidant properties of benzoic acid analogues: a structure/redox potential relationship study.

    Science.gov (United States)

    Franck, Thierry; Mouithys-Mickalad, Ange; Robert, Thierry; Ghitti, Gianangelo; Deby-Dupont, Ginette; Neven, Philippe; Serteyn, Didier

    2013-11-25

    We investigated the antioxidant activities of some phenolic acid derivatives on a cell free system and on cellular and enzymatic models involved in inflammation. The stoichiometric antioxidant activities of phenolic acid derivatives were studied by measuring their capacity to scavenge the radical cation 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS(+)) and reactive oxygen species (ROS) produced by stimulated neutrophils. The anticatalytic antioxidant capacity of the molecules was evaluated on the activity of myeloperoxidase (MPO), an oxidant enzyme present in and released by the primary granules of neutrophils. The ROS produced by PMA-stimulated neutrophils were measured by lucigenin-enhanced chemiluminescence (CL) and the potential interaction of the molecules with MPO was investigated without interferences due to medium by Specific Immuno-Extraction Followed by Enzyme Detection (SIEFED). The antioxidant activities of the phenolic compounds were correlated to their redox potentials measured by differential pulse voltammetry (DPV), and discussed in relation to their molecular structure. The ability of the phenolic molecules to scavenge ABTS radicals and ROS derived from neutrophils was inversely correlated to their increased redox potential. The number of hydroxyl groups (three) and their position (catechol) were essential for their efficacy as stoichiometric antioxidants or scavengers. On MPO activity, the inhibitory capacity of the molecules was not really correlated with their redox potential. Likewise, for the inhibition of MPO activity the number of OH groups and mainly the elongation of the carboxylic group were essential, probably by facilitating the interaction with the active site or the structure of the enzyme. The redox potential measurement, combined with ABTS and CL techniques, seems to be a good technique to select stoichiometric antioxidants but not anticatalytic ones, as seen for MPO, what rather involves a direct interaction with

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

    Science.gov (United States)

    Sharma-Judd, Malavika M.

    2000-12-01

    The purpose of this investigation was to identify the structure/property relationship of spray formed 7XXX series alloys. High solute, ultra-high strength 7XXX series aluminum alloys with solute contents close to equilibrium solid solubility limits of the Al-Zn-Mg-Cu system have been produced by rapid solidification using spray deposition. The process yields massive preforms directly from the liquid state. Various elements, including chromium, manganese, silver, zirconium and scandium, were incorporated to produce a variety of microstructures and mechanical properties. SiC particulate was added to these same alloy compositions to produce metal matrix composites (MMCs). The resulting extruded products in the T6 and T7 conditions were evaluated and compared. Under peak-aged conditions in the unreinforced materials, strengths in excess of 860 MPa were achieved, with one alloy exceeding 900 MPa. Apart from the elongation to failure, the mechanical properties of the composite materials were equal to or superior to those of their unreinforced counterparts. The superior strength properties of the spray formed alloys were attributed to two major substructures with different scale; nanometer sized eta ' metastable precipitates and slightly larger, but finely distributed dispersoids. The large volume fraction of plate-like eta' precipitates (average size 58A, ranging up to 73 A in diameter) were identified as having a hexagonal structure with lattice parameters a = 0.488 nm and c = 1.376. The remarkable strengthening is predominantly attributed to precipitation hardening. The enhanced mechanical properties of the MMC materials are attributed to the increased dislocation density, and thus, a higher concentration of structural particles compared to the unreinforced materials. Higher gas-to-metal ratios of 4.45, as opposed to lower gas-to-metal ratios of 1.95 produced a refined grain structure with an evenly distributed second phase. In both unreinforced and MMC materials

  5. Reactive magnetron sputtering of Nb-doped TiO{sub 2} films: Relationships between structure, composition and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Stefan, E-mail: seeger@out-ev.de [Optotransmitter-Umweltschutz-Technologie e.V., Köpenicker Str. 325, 12555 Berlin (Germany); Ellmer, Klaus [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Weise, Michael [Optotransmitter-Umweltschutz-Technologie e.V., Köpenicker Str. 325, 12555 Berlin (Germany); Gogova, Daniela [Central Lab of Solar Energy and New Energy Sources at the Bulg. Acad. Sci., Blvd. Tzarigradsko shose 72, Sofia (Bulgaria); Abou-Ras, Daniel [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Mientus, Rainald [Optotransmitter-Umweltschutz-Technologie e.V., Köpenicker Str. 325, 12555 Berlin (Germany)

    2016-04-30

    Niobium-doped TiO{sub 2} films as highly transparent conducting oxides for electrical contacts were investigated. As-deposited films were amorphous and exhibited high resistivities ranging from 10 to 10{sup 5} Ω cm. A slight oxygen deficiency in as-deposited films was essential to gain low resistivities (10{sup −3} Ω cm) and low optical absorption coefficients (α{sub 550} {sub nm} < 2 × 10{sup 3} cm{sup −1}) in the annealed films. Therefore, we controlled the oxygen stoichiometry during the film deposition by adjusting the magnetron discharge voltage, while the oxygen gas flow was kept constant. The Hall mobility of degenerately doped films (electron concentration > 10{sup 20} cm{sup −3}) increased with decreasing substrate temperature owing to metal-like phonon scattering in these samples. - Highlights: • Slight oxygen deficient as-deposited films were highly conductive after annealing. • Control of oxygen stoichiometry by adjusting the discharge voltage during deposition • Electron mobility at room temperature is limited due to scattering at phonons. • Films exhibited large average crystallite sizes with planar structural defects.

  6. Molecular dynamics simulations of structure-property relationships of Tween 80 surfactants in water and at interfaces.

    Science.gov (United States)

    Tang, Xueming; Huston, Kyle J; Larson, Ronald G

    2014-11-13

    We build a united atom model for Tween 80 (polyoxyethylene sorbitan oleates), based on the GROMOS53A6(OXY+D) force field, and apply it to two stereoisomers, three constitutional isomers, and three structures with one, two, and three tails, to represent components in the Tween 80 commercial mixture. In a preassembled micelle containing 60 molecules, the distribution of Tween tail and ethylene oxide head groups is found to be insensitive to stereoisomerization but sensitive to changes in relative lengths of the four polyoxyethylene head groups. At the air-water and oil-water interfaces, the interfacial tension is significantly lower for the constitutional isomer with a shorter W headgroup, which attaches the tail to the sorbitan ring, and for Tween 80 isomers with more than one tail group. The results indicate the possible scope for improvement in the design of polyoxyethylene sorbitan oleates with improved surface tension reduction or better spreading at the oil-water interface. We also report surfactant component distribution profiles within preassembled micelles and at interfaces that can be used for validating coarse-grained surfactant models needed for simulation of self-assembly of Tween 80 surfactant mixtures.

  7. Quantitative structure-property relationships of retention indices of some sulfur organic compounds using random forest technique as a variable selection and modeling method.

    Science.gov (United States)

    Goudarzi, Nasser; Shahsavani, Davood; Emadi-Gandaghi, Fereshteh; Chamjangali, Mansour Arab

    2016-10-01

    In this work, a noble quantitative structure-property relationship technique is proposed on the basis of the random forest for prediction of the retention indices of some sulfur organic compounds. In order to calculate the retention indices of these compounds, the theoretical descriptors produced using their molecular structures are employed. The influence of the significant parameters affecting the capability of the developed random forest prediction power such as the number of randomly selected variables applied to split each node (m) and the number of trees (nt ) is studied to obtain the best model. After optimizing the nt and m parameters, the random forest model conducted for m = 70 and nt = 460 was found to yield the best results. The artificial neural network and multiple linear regression modeling techniques are also used to predict the retention index values for these compounds for comparison with the results of random forest model. The descriptors selected by the stepwise regression and random forest model are used to build the artificial neural network models. The results achieved showed the superiority of the random forest model over the other models for prediction of the retention indices of the studied compounds.

  8. Towards the Application of Structure-Property Relationship Modeling in Materials Science: Predicting the Seebeck Coefficient for Ionic Liquid/Redox Couple Systems.

    Science.gov (United States)

    Sosnowska, Anita; Barycki, Maciej; Gajewicz, Agnieszka; Bobrowski, Maciej; Freza, Sylwia; Skurski, Piotr; Uhl, Stefanie; Laux, Edith; Journot, Tony; Jeandupeux, Laure; Keppner, Herbert; Puzyn, Tomasz

    2016-06-01

    This work focuses on determining the influence of both ionic-liquid (IL) type and redox couple concentration on Seebeck coefficient values of such a system. The quantitative structure-property relationship (QSPR) and read-across techniques are proposed as methods to identify structural features of ILs (mixed with LiI/I2 redox couple), which have the most influence on the Seebeck coefficient (Se ) values of the system. ILs consisting of small, symmetric cations and anions with high values of vertical electron binding energy are recognized as those with the highest values of Se . In addition, the QSPR model enables the values of Se to be predicted for each IL that belongs to the applicability domain of the model. The influence of the redox-couple concentration on values of Se is also quantitatively described. Thus, it is possible to calculate how the value of Se will change with changing redox-couple concentration. The presence of the LiI/I2 redox couple in lower concentrations increases the values of Se , as expected.

  9. Validating the German version of the Quality of Relationship Inventory: confirming the three-factor structure and report of psychometric properties.

    Directory of Open Access Journals (Sweden)

    Iris Reiner

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

  10. A review of quantitative structure-property relationships for the fate of ionizable organic chemicals in water matrices and identification of knowledge gaps.

    Science.gov (United States)

    Nolte, Tom M; Ragas, Ad M J

    2017-03-22

    Many organic chemicals are ionizable by nature. After use and release into the environment, various fate processes determine their concentrations, and hence exposure to aquatic organisms. In the absence of suitable data, such fate processes can be estimated using Quantitative Structure-Property Relationships (QSPRs). In this review we compiled available QSPRs from the open literature and assessed their applicability towards ionizable organic chemicals. Using quantitative and qualitative criteria we selected the 'best' QSPRs for sorption, (a)biotic degradation, and bioconcentration. The results indicate that many suitable QSPRs exist, but some critical knowledge gaps remain. Specifically, future focus should be directed towards the development of QSPR models for biodegradation in wastewater and sediment systems, direct photolysis and reaction with singlet oxygen, as well as additional reactive intermediates. Adequate QSPRs for bioconcentration in fish exist, but more accurate assessments can be achieved using pharmacologically based toxicokinetic (PBTK) models. No adequate QSPRs exist for bioconcentration in non-fish species. Due to the high variability of chemical and biological species as well as environmental conditions in QSPR datasets, accurate predictions for specific systems and inter-dataset conversions are problematic, for which standardization is needed. For all QSPR endpoints, additional data requirements involve supplementing the current chemical space covered and accurately characterizing the test systems used.

  11. Structure-property relationship for in vitro siRNA delivery performance of cationic 2-hydroxypropyl-β-cyclodextrin: PEG-PPG-PEG polyrotaxane vectors.

    Science.gov (United States)

    Badwaik, Vivek D; Aicart, Emilio; Mondjinou, Yawo A; Johnson, Merrell A; Bowman, Valorie D; Thompson, David H

    2016-04-01

    Nanoparticle-mediated siRNA delivery is a promising therapeutic approach, however, the processes required for transport of these materials across the numerous extracellular and intracellular barriers are poorly understood. Efficient delivery of siRNA-containing nanoparticles would ultimately benefit from an improved understanding of how parameters associated with these barriers relate to the physicochemical properties of the nanoparticle vectors. We report the synthesis of three Pluronic(®)-based, cholesterol end-capped cationic polyrotaxanes (PR(+)) threaded with 2-hydroxypropyl-β-cyclodextrin (HPβCD) for siRNA delivery. The biological data showed that PR(+):siRNA complexes were well tolerated (∼90% cell viability) and produced efficient silencing (>80%) in HeLa-GFP and NIH 3T3-GFP cell lines. We further used a multi-parametric approach to identify relationships between the PR(+) structure, PR(+):siRNA complex physical properties, and biological activity. Small angle X-ray scattering and cryoelectron microscopy studies reveal periodicity and lamellar architectures for PR(+):siRNA complexes, whereas the biological assays, ζ potential measurements, and imaging studies suggest that silencing efficiency is influenced by the effective charge ratio (ρeff), polypropylene oxide (PO) block length, and central PO block coverage (i.e., rigidity) of the PR(+) core. We infer from our findings that more compact PR(+):siRNA nanostructures arising from lower molecular weight, rigid rod-like PR(+) polymer cores produce improved silencing efficiency relative to higher molecular weight, more flexible PR(+) vectors of similar effective charge. This study demonstrates that PR(+):siRNA complex formulations can be produced having higher performance than Lipofectamine(®) 2000, while maintaining good cell viability and siRNA sequence protection in cell culture.

  12. Structure-property relationships in an Al matrix Ca nanofilamentary composite conductor with potential application in high-voltage power transmission

    Science.gov (United States)

    Tian, Liang

    This study investigated the processing-structure-properties relationships in an Al/Ca composites using both experiments and modeling/simulation. A particular focus of the project was understanding how the strength and electrical conductivity of the composite are related to its microstructure in the hope that a conducting material with light weight, high strength, and high electrical conductivity can be developed to produce overhead high-voltage power transmission cables. The current power transmission cables (e.g., Aluminum Conductor Steel Reinforced (ACSR)) have acceptable performance for high-voltage AC transmission, but are less well suited for high-voltage DC transmission due to the poorly conducting core materials that support the cable weight. This Al/Ca composite was produced by powder metallurgy and severe plastic deformation by extrusion and swaging. The fine Ca metal powders have been produced by centrifugal atomization with rotating liquid oil quench bath, and a detailed study about the atomization process and powder characteristics has been conducted. The microstructure of Al/Ca composite was characterized by electron microscopy. Microstructure changes at elevated temperature were characterized by thermal analysis and indirect resistivity tests. The strength and electrical conductivity were measured by tensile tests and four-point probe resistivity tests. Predicting the strength and electrical conductivity of the composite was done by micro-mechanics-based analytical modeling. Microstructure evolution was studied by mesoscale-thermodynamics-based phase field modeling and a preliminary atomistic molecular dynamics simulation. The application prospects of this composite was studied by an economic analysis. This study suggests that the Al/Ca (20 vol. %) composite shows promise for use as overhead power transmission cables. Further studies are needed to measure the corrosion resistance, fatigue properties and energized field performance of this composite.

  13. Structure-property and composition-property relationships for poly(ethylene terephthalate) surfaces modified by helium plasma-based ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Toth, A., E-mail: totha@chemres.hu [Institute of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17 (Hungary); Veres, M. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49 (Hungary); Kereszturi, K.; Mohai, M.; Bertoti, I.; Szepvoelgyi, J. [Institute of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 17 (Hungary)

    2011-10-01

    The surfaces of untreated and helium plasma-based ion implantation (He PBII) treated poly(ethylene terephthalate) (PET) samples were characterised by reflectance colorimetry, contact angle studies and measurements of surface electrical resistance. The results were related to the structural and compositional data obtained by the authors earlier on parallel samples by XPS and Raman spectroscopy. Inverse correlations between lightness and I{sub D}/I{sub G} ratio and between chroma and I{sub D}/I{sub G} ratio were obtained, suggesting that the PBII-treated PET samples darken and their colourfulness decreases with the increase of the portion of aromatic sp{sup 2} carbon rings in the chemical structure of the modified layer. Direct correlation between water contact angle and the I{sub D}/I{sub G} ratio and inverse correlations between surface energy and I{sub D}/I{sub G} ratio and between dispersive component of surface energy and I{sub D}/I{sub G} ratio were found, reflecting that surface wettability, surface energy and its dispersive component decrease with the formation of surface structure, characterised again by enhanced portion of aromatic sp{sup 2} carbon rings. The surface electrical resistance decreased with the increase of the surface C-content determined by XPS and also with the increase of the surface concentration of conjugated double bonds, reflected by the increase of the {pi} {yields} {pi}* shake-up satellite of the C 1s peak.

  14. Structure-property relationships along the Fe-substituted CuInS2 series: Tuning of thermoelectric and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, Johanna D.; Gourdon, Olivier; Ranmohotti, Kulugammana G.S.; Takas, Nathan J.; Djieutedjeu, Honore; Poudeu, Pierre F.P.; Aitken, Jennifer A. [Michigan; (Duquesne); (ORNL)

    2014-07-03

    CuIn1-xFexS2 (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 CuIn0.85Fe0.15S2 sample, which contains a minute secondary phase. These refinements also verify that iron resides on the indium site in the CuIn1-xFexS2 materials. CuIn0.875Fe0.125S2 displayed the lowest total thermal conductivity of the series, 1.37 W m-1 K-1 at 570 K, as well as the highest thermopower, -172 μV K-1 at 560 K. The electrical conductivity increases over six times upon going from CuInS2 to CuIn0.875Fe0.125S2. These improved properties result in an increase in the thermoelectric figure of merit (ZT) of CuInS2 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.

  15. 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 20% of their cell wall consisting of dislocations. For this data set the percentage of dislocations...

  16. Partitioning and lipophilicity in quantitative structure-activity relationships.

    OpenAIRE

    Dearden, J. C.

    1985-01-01

    The history of the relationship of biological activity to partition coefficient and related properties is briefly reviewed. The dominance of partition coefficient in quantitation of structure-activity relationships is emphasized, although the importance of other factors is also demonstrated. Various mathematical models of in vivo transport and binding are discussed; most of these involve partitioning as the primary mechanism of transport. The models describe observed quantitative structure-ac...

  17. 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 p......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...

  18. Application of structure-metabolism relationships in the identification of a selective endothelin A antagonist, BMS-193884, with favourable pharmacokinetic properties.

    Science.gov (United States)

    Humphreys, W G; Obermeier, M T; Barrish, J C; Chong, S; Marino, A M; Murugesan, N; Wang-Iverson, D; Morrison, R A

    2003-11-01

    1. Based on binding affinity, 2'-amino-N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-methylpropyl)[1,1'-biphenyl]-2-sulfonamide (2) was identified as an initial lead in a programme to identify selective endothelin (ET) receptor antagonists. However, the compound was extensively metabolized in preclinical animal species and human in vitro systems due to oxidative biotransformation. 2. To optimize this structural class, the site of metabolism of 2 was determined. This allowed for focussed structure-activity and structure-metabolism studies aimed at finding more metabolically stable analogues that maintained potency. New analogues were screened for their ET binding characteristics and their stability in rat and human liver microsomes. 3. The use of the microsomal stability screen was tested by the determination of the pharmacokinetic parameters of select analogues. A good correlation was found between reduced rates of rat microsomal metabolism and reduced clearance in the rat. 4. N-(3,4-dimethyl-5-isoxazolyl)-4'-(2-oxazolyl)[1,1'-biphenyl]-2-sulfonamide (3) was identified as an analogue with improved in vitro properties and further studies revealed that the compound had improved pharmacokinetic properties. 5. N-[[2'-[[(3,4-dimethyl-5-isoxazolyl)amino]sulfonyl]-4-(2-oxazolyl)[1,1'-biphenyl]-2-yl]methyl]acetamide (4) was subsequently identified as a compound with superior in vitro properties compared with compound 3, but when tested in vivo it had a substantially increased rate of clearance. Further studies demonstrated that the clearance of this closely related structural analogue was not dictated by metabolic processes, but was mediated by transport-mediated direct biliary excretion. 6. The utility of screening for in vitro liver microsomal stability as part of the lead optimization process for compounds with metabolic liabilities was shown. It was also shown that relatively small molecular changes can dramatically change the disposition of closely related analogues and care

  19. Quantitative structure-property relationship study of the solubility of thiazolidine-4-carboxylic acid derivatives using ab initio and genetic algorithm-partial least squares

    Institute of Scientific and Technical Information of China (English)

    Ali Niazi; Saeed Jameh-Bozorghi; Davood Nori-Shargh

    2007-01-01

    A quantitative structure-activity relationships (QSAR) study is suggested for the prediction of solubility of some thiazolidine-4-carboxylic acid derivatives in aqueous solution. Ab initio theory was used to calculate some quantum chemical descriptors including electrostatic potentials and local charges at each atom, HOMO and LUMO energies, etc. Modeling of the solubility of thiazolidine4-carboxylic acid derivatives as a function of molecular structures was established by means of the partial least squares (PLS). The subset of descriptors, which resulted in the low prediction error, was selected by genetic algorithm. This model was applied for the prediction of the solubility of some thiazolidine-4-carboxylic acid derivatives, which were not in the modeling procedure. The relative errors of prediction lower that -4% was obtained by using GA-PLS method. The resulted model showed high prediction ability with RMSEP of 3.8836 and 2.9500 for PLS and GA-PLS models, respectively.

  20. Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal, E-mail: manashaldar@cgcri.res.in

    2015-01-15

    The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural properties by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.

  1. 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.

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

    CERN Document Server

    Ganesan, Aravindhan; Wang, Feng

    2014-01-01

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

  3. Reversed- and normal-phase liquid chromatography in quantitative structure retention-property relationships of newly synthesized seco-androstene derivatives.

    Science.gov (United States)

    Milošević, Nataša P; Stojanović, Srdjan Z; Penov-Gaši, Katarina; Perišić-Janjić, Nada; Kaliszan, Roman

    2014-01-01

    The rational preselection of drug candidates includes also correlation between physico-chemical properties (lipophilicity, as the key one) and pharmacokinetic properties, as well as pharmacodynamic activity. Lipophilicity can be determined alternatively by chromatographic methods. Chromatographic behavior of nineteen newly synthesized derivatives of 16-cyano-16,17-seco-5-androstene has been studied by reversed-phase and normal-phase thin-layer chromatography (RP- and NP-TLC). Commercial plates RP-C18-HPTLC and water-dioxane and water-acetonitrile, as well as Lux(®) silica gel plates and toluene-dioxane and toluene-acetonitrile mixtures with different volume fractions of the solvents were used. Retention constants RM(0) and C0 for each compound were determined and correlated with (i) theoretical log P values and (ii) pharmacokinetic predictors determined in silico. Significant linear relationship was found between RP TLC retention constants, RM(0), and computational logP values as well as between NP TLC retention constants, C0, and logP. Lipophilicity values for the analytes, determined by RP TLC and NP TLC, were also correlated with computer calculated absorption constants, affinity for plasma proteins, volume of distribution and logarithm of blood-brain permeation. Significant linear relationships were obtained. These relations were further improved by introducing other regressors, as molecular size descriptors (molecular mass and/or volume) and a molecular polarity descriptor (total polar surface area). Retention parameters, RM(0) and C0, are recommended for lipophilicity expression of analyzed compounds. In silico pharmacokinetic descriptors for the analytes can be expressed as function of the lipophilicity determined by chromatographic methods, the size and the polarity of the molecules expressed as molecular mass/volume and total polar surface area. The analyzed seco-androstene derivatives have adequate lipophilicity which should provide druglikeness and good

  4. Evaluation of the Therapeutic Properties of Mastoparan- and Sifuvirtide- Derivative Antimicrobial Peptides Using Chemical Structure-Function Relationship - in vivo and in silico Approaches.

    Science.gov (United States)

    Avram, Speranta; Mernea, Maria; Borcan, Florin; Mihailescu, Dan

    2016-01-01

    Antimicrobial peptides, also called body defense peptides, are chemical structures widely distributed across the animal and vegetal kingdoms that have a fundamental role as part of the immune system. These peptides are used against a wide range of pathogens, such as Gram-negative and - positive bacteria, fungi and viruses, etc. Their action spectrum makes them important for the pharmaceutical industry, as they could represent templates for the design of new and more potent structures by using drug design and drug delivery systems. Here we present the antimicrobial activity against Bacillus subtilis (expressed as minimal inhibitory concentration values) for 33 mastoparan analogs and their new derivatives by quantitative structure-activity relationship method (2D, aligned and also non-aligned 3D-QSAR). We establish the contribution to antimicrobial activity of molecular descriptors like hydrophobicity, hydrogen bond donor and steric hindrance, correlated with contributions from the membrane environment (sodium, potassium, chloride ions). Also the studies of HIV-1 fusion inhibitor sifuvirtide and its analogs are presented in context of interaction with lipid structures during fusion and delivery of these drugs.

  5. 15 CFR 14.37 - Property trust relationship.

    Science.gov (United States)

    2010-01-01

    ... COMMERCIAL ORGANIZATIONS Post-Award Requirements Property Standards § 14.37 Property trust relationship. Real property, equipment, intangible property and debt instruments that are acquired or improved with Federal... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Property trust relationship....

  6. 20 CFR 435.37 - Property trust relationship.

    Science.gov (United States)

    2010-04-01

    ..., AND COMMERCIAL ORGANIZATIONS Post-Award Requirements Property Standards § 435.37 Property trust relationship. Real property, equipment, intangible property and debt instruments that are acquired or improved... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Property trust relationship. 435.37...

  7. 45 CFR 74.37 - Property trust relationship.

    Science.gov (United States)

    2010-10-01

    ... ORGANIZATIONS, AND COMMERCIAL ORGANIZATIONS Post-Award Requirements Property Standards § 74.37 Property trust relationship. Real property, equipment, intangible property and debt instruments that are acquired or improved... 45 Public Welfare 1 2010-10-01 2010-10-01 false Property trust relationship. 74.37 Section...

  8. Presence of Peierls pairing and absence of insulator-to-metal transition in VO2 (A): a structure-property relationship study.

    Science.gov (United States)

    Popuri, S R; Artemenko, A; Decourt, R; Villesuzanne, A; Pollet, M

    2017-03-01

    Layered vanadium oxides have been extensively explored due to their interesting metal-insulator transitions and energy conversion/storage applications. In the present study, we have successfully synthesized VO2 (A) polymorph powder samples by a single-step hydrothermal synthesis process and consolidated them using spark plasma sintering. The structural and electronic properties of VO2 (A) are measured over a large temperature range from liquid helium, across the structural transition (400-440 K) and up to 500 K. The structural analysis around this transition reveals an antiferrodistorsive to partially ferrodistorsive ordering upon cooling. It is followed by a progressive antiferromagnetic spin pairing which fully settles at about 150 K. The transport measurements show that, in contrast to the rutile archetype VO2 (R/M1), the structural transition comes with a transition from semiconductor to band-type insulator. Under these circumstances, we propose a scenario with a high temperature antiferrodistorsive paramagnetic semiconducting phase, followed by an intermediate regime with a partially ferrodistorsive paramagnetic semiconducting phase, and finally a low temperature partially ferrodistorsive antiferromagnetic band insulator phase with a possible V-V Peierls-type pairing.

  9. Structure-permeability relationship analysis of the permeation barrier properties of the stratum corneum and viable epidermis/dermis of rat skin.

    Science.gov (United States)

    Yamaguchi, Koji; Mitsui, Tetsuya; Aso, Yoshinori; Sugibayashi, Kenji

    2008-10-01

    The purpose of this study was to evaluate structure-permeability relationships for chemicals through stratum corneum (SC) and viable epidermis/dermis (VED). In vitro skin permeation of ten compounds through excised rat skin was analyzed based on a two-layer diffusion model and the diffusion coefficients in SC (D(SC)) and VED (D(VED)) were determined. The relationships between the permeation parameters and the physicochemical parameters (octanol-water partition coefficient (log K(o/w)), and hydrogen bond donor number (HBD)) of the compounds were analyzed. D(SC) increased as lipophilicity increased, whereas D(VED) decreased for log K(o/w) > 2. Increases in log K(o/w) caused a decrease in the permeability coefficient from SC through VED (P(VED/SC)) for log K(o/w) > 1. The simulation study suggests that the in vitro skin permeation of a highly lipophilic compound is strongly controlled by skin thickness due to low diffusivity in VED. The present study suggests that VED act as a considerable permeation barrier for highly lipophilic compounds due to low diffusivity.

  10. 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

    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

  11. Structural Antitumoral Activity Relationships of Synthetic Chalcones

    Science.gov (United States)

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

    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 HepG2 cells. The absence of methoxy substituents in the B ring of synthetic 2’-hydroxychalcones, showed the mayor structure-activity pattern along the series. PMID:19333443

  12. Glucoamylase: structure/function relationships, and protein engineering

    DEFF Research Database (Denmark)

    Sauer, J; Sigurskjold, B W; Christensen, U;

    2000-01-01

    fundamental structure/function relationships in the binding and catalytic mechanisms. In parallel, issues of relevance for application have been pursued using protein engineering to improve the industrial properties. The present review focuses on recent findings on the catalytic site, mechanism of action...

  13. Investigation of structure-property relationships of polyisobutylene-based biomaterials: Morphology, thermal, quasi-static tensile and long-term dynamic fatigue behavior.

    Science.gov (United States)

    Götz, C; Lim, G T; Puskas, J E; Altstädt, V

    2012-06-01

    This study examines the morphology, thermal, quasi-static and long-term dynamic creep properties of one linear and three arborescent polyisobutylene-based block copolymers (L_SIBS31, D_IBS16, D_IBS27 and D_IBS33). Silicone rubber, a common biopolymer, was considered as a benchmark material for comparison. A unique hysteretic testing methodology of Stepwise Increasing Load Test (SILT) and Single Load Test (SLT) was used in this study to evaluate the long-term dynamic fatigue performance of these materials. Our experimental findings revealed that the molecular weight of polyisobutylene (PIB) and polystyrene (PS) arms [M(n)(PIB(arm)) and M(n)(PS(arm))], respectively had a profound influence on the nano-scaled phase separation, quasi-static tensile, thermal transition, and dynamic creep resistance behaviors of these PIB-based block copolymers. However, silicone rubber outperformed the PIB-based block copolymers in terms of dynamic creep properties due to its chemically crosslinked structure. This indicates a need for a material strategy to improve the dynamic fatigue and creep of this class of biopolymers to be considered as alternative to silicone rubber for biomedical devices.

  14. 29 CFR 95.37 - Property trust relationship.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 1 2010-07-01 2010-07-01 true Property trust relationship. 95.37 Section 95.37 Labor..., AND OTHER NON-PROFIT ORGANIZATIONS, AND WITH COMMERCIAL ORGANIZATIONS, FOREIGN GOVERNMENTS... Requirements Property Standards § 95.37 Property trust relationship. Real property, equipment,...

  15. 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.

  16. 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

  17. Solution structure and stability against digestion of rproBnIb, a recombinant 2S albumin from rapeseed: relationship to its allergenic properties.

    Science.gov (United States)

    Pantoja-Uceda, David; Palomares, Oscar; Bruix, Marta; Villalba, Mayte; Rodríguez, Rosalía; Rico, Manuel; Santoro, Jorge

    2004-12-28

    NMR spectroscopy has been used to determine the solution structure of the precursor form of the recombinant napin BnIb, rproBnIb, a 2S albumin, 109-residue protein from the seeds of Brassica napus. More than 90% of the side-chain proton resonances were unambiguously assigned from the analysis of two-dimensional correlation (COSY), total correlation (TOCSY), and nuclear Overhauser effect (NOESY) spectra. The final structures were computed by using restrained molecular dynamics on the basis of 1316 upper-limit distance constraints derived from NOE cross-correlation intensities. The computed structures exhibited a root-mean-square deviation (RMSD) radius of 0.66 A for the backbone and 1.16 A for the side-chain heavy atoms of the structural core. The resulting structure consists of five amphipathic helices arranged in a right-handed super helix, a folding motif found in other proteins of the prolamin superfamily. As in the case of the mature protein, the recombinant precursor behaves as a plant food allergen. To trace out the origin and characteristics of its allergenic properties, rproBnIb was assayed against simulated gastric fluid and found to be very resistant to proteolysis. Also, heat treatment of the protein followed up to 85 degrees C by circular dichroism showed a very limited unfolding, which was recovered after cooling to 20 degrees C, indicating a high thermal stability. These results suggest that rproBnIb, as other 2S albumins, may be able to reach the gut immune system intact. A comparison of the putative epitopes against IgE antibodies of the three members of the prolamine family [2S albumins, nonspecific lipid transfer proteins (nsLTPs), and alpha-amylase/trypsin inhibitors] indicates that there are not common surfaces of interaction with IgE. Though the epitopes appear to be located in different regions of the proteins, they do comply with the requirements of being solvent-exposed and flexible.

  18. Study of physicochemical interaction of aryloxyaminopropanol derivatives with teicoplanin and vancomycin phases in view of quantitative structure-property relationship studies.

    Science.gov (United States)

    Boronová, Katarína; Lehotay, Jozef; Hroboňová, Katarína; Armstrong, Daniel W

    2013-08-02

    The aim of this work was to study the physicochemical interactions between chiral stationary phases and chiral molecules and to elucidate which of the specific interactions are more or less important. The HPLC separation of 58 aryloxyaminopropanols was performed on two chiral stationary phases containing the macrocyclic antibiotics teicoplanin or vancomycin and using a methanol/acetonitrile/acetic acid/triethylamine mobile phase (volume ratios 45/55/0.3/0.2). The resolution of enantiomers (Rij) as the target variable was predicted for the mentioned kind of compounds by means of thoroughly selected descriptors provided by the applied Dragon software. The created QSPR models can be considered as a way to explore and discover new relationships or interactions between the quantitative structure and resolution of enantiomers. For calculation and validation of the QSPR models, different modelling methodologies were applied based on MLR (multiple linear regression) and ANN (artificial neural network) techniques. Both methods exhibit an ability for successful prediction of the enantioresolution characteristics of the studied molecules. The results seem to demonstrate that it is possible to predict resolution values of enantiomeric separations of related compounds on given chromatographic systems.

  19. Structure-Function Relationships in Semiconducting Polymers for Organic Photovoltaics

    OpenAIRE

    Kavulak, David Fredric Joel

    2010-01-01

    The major body of this work investigates how the chemical structure of conjugated polymers relates to the fundamental operating mechanism of organic photovoltaic devices. New conjugated polymers were characterized and their optical and electronic properties tested and correlated with their power conversion efficiencies as the active layer in polymer solar cells. From these experiments general structure/function relationships are drawn with an eye toward developing universal guidelines for con...

  20. The synthesis, photophysical and photobiological properties and in vitro structure-activity relationships of a set of silicon phthalocyanine PDT photosensitizers.

    Science.gov (United States)

    He, J; Larkin, H E; Li, Y S; Rihter, D; Zaidi, S I; Rodgers, M A; Mukhtar, H; Kenney, M E; Oleinick, N L

    1997-03-01

    Four silicon phthalocyanine photosensitizers have been prepared and studied in an effort to learn more about the structural features that a silicon phthalocyanine must have in order to be a good photodynamic therapy (PDT) photosensitizer. The compounds that have been studied are the known phthalocyanines HOSiPcOSi(CH3)2-(CH2)3N(CH3)2, Pc 4; and SiPc[OSi(CH3)2(CH2)3N(CH3)2]2, Pc 12; and the new photosensitizers HOSiPcOSi(CH3)2- (CH2)3N(CH2CH3)(CH2)2N(CH3)2, Pc 10; and SiPc[OSi (CH3)2(CH2)3N(CH2CH3)(CH2)2N(CH3)2]2, Pc 18. The triplet lifetimes of the four photosensitizers, their singlet oxygen quantum yields, their ability to photoenhance the generation of lipid peroxidation products in human erythrocyte ghosts, their ability to partition into V79 cells and their ability to photokill V79 and L5178Y-R cells have been determined. It is concluded that the presence of a small axial ligand (e.g. an OH ligand) is not necessary for efficient photosensitization, the presence of two aminosiloxy ligands generally provides at least as good photosensitization as one such ligand, and the presence of an elongated diaminosiloxy axial ligand rather than a short aminosiloxy ligand is less desirable. Further, it is concluded that the presence of structural features leading to improvement in the association between the photosensitizers and important cellular targets are more useful than those leading to improvements in their already acceptable photophysical and photochemical properties.

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

    Science.gov (United States)

    McQuade, Ryan R.; Dolgos, Michelle R.

    2016-10-01

    Piezoelectric materials are increasingly being investigated for energy harvesting applications where (1-x)Na0.5Bi0.5TiO3-(x)BaTiO3 (NBT-BT) is an important lead-free piezoelectric material with potential to be used as an actuator in energy harvesting devices. Much effort has been put into modifying NBT-BT to tune the properties for specific applications, but there is currently no consensus regarding the structure-property relationships in this material, making targeted, rational design a major challenge. In this review, we will summarize the current body of knowledge of NBT-BT and discuss contradicting studies, unresolved problems, and future directions in the field.

  2. Structure-Activity Relationships in Nitro-Aromatic Compounds

    Science.gov (United States)

    Vogt, R. A.; Rahman, S.; Crespo-Hernández, C. E.

    Many nitro-aromatic compounds show mutagenic and carcinogenic properties, posing a potential human health risk. Despite this potential health hazard, nitro-aromatic compounds continue to be emitted into ambient air from municipal incinerators, motor vehicles, and industrial power plants. As a result, understanding the structural and electronic factors that influence mutagenicity in nitro-aromatic compounds has been a long standing objective. Progress toward this goal has accelerated over the years, in large part due to the synergistic efforts among toxicology, computational chemistry, and statistical modeling of toxicological data. The concerted influence of several structural and electronic factors in nitro-aromatic compounds makes the development of structure-activity relationships (SARs) a paramount challenge. Mathematical models that include a regression analysis show promise in predicting the mutagenic activity of nitro-aromatic compounds as well as in prioritizing compounds for which experimental data should be pursued. A major challenge of the structure-activity models developed thus far is their failure to apply beyond a subset of nitro-aromatic compounds. Most quantitative structure-activity relationship papers point to statistics as the most important confirmation of the validity of a model. However, the experimental evidence shows the importance of the chemical knowledge in the process of generating models with reasonable applicability. This chapter will concisely summarize the structural and electronic factors that influence the mutagenicity in nitro-aromatic compounds and the recent efforts to use quantitative structure-activity relationships to predict those physicochemical properties.

  3. Effect of Out-of-Plane Alkyl Group's Position in Dye-Sensitized Solar Cell Efficiency: A Structure-Property Relationship Utilizing Indoline-Based Unsymmetrical Squaraine Dyes.

    Science.gov (United States)

    Alagumalai, Ananthan; M K, Munavvar Fairoos; Vellimalai, Punitharasu; Sil, Manik Chandra; Nithyanandhan, Jayaraj

    2016-12-28

    Squaraine dyes are promising chromophores to harvest visible and near-infrared (NIR) photons. A series of indoline-based unsymmetrical squaraine (SQ) dyes that contain alkyl chains at sp(3) C- and N- atoms of indoline moieties with a carboxylic acid anchoring group were synthesized. The optical and electrochemical properties of the SQ dyes in solution were nearly identical as there was no change in the D-A-D SQ framework; however, remarkable changes with respect to the power conversion efficiencies (PCE) were observed depending upon the position of alkyl groups in the dye. Introduction of alkyl groups to the indoline unit that was away from anchoring unit were helped in more dye loading with controlled organization of dyes on surface, increased charge transfer resistance, long electron lifetime, and hence higher PCE than that of the corresponding isomer in which the alkyl groups funtionalized indoline unit contains the carboxylic acid anchoring group. Careful analysis of incident photon-to-current conversion efficiency (IPCE) profiles indicated the presence of aggregated structure on the TiO2 surface that contributes to the charge injection in the presence of a coadsorbent. A dye-sensitized solar cell (DSSC) device made out of SQ5 was achieved an efficiency of 9.0%, with an open-circuit potential (Voc) of 660 mV and short-circuit current density (Jsc) of 19.82 mA/cm(2), under simulated AM 1.5G illumination (100 mW/cm(2)). The IPCE profile of SQ5 shows an onset near to 750 nm with a good quantum efficiency (>80%) in the range of 550-700 nm, indicating the importance of self-organization of dyes on the TiO2 surface for an efficient charge injection. This present investigation revealed the importance of position of alkyl groups in the squaraine-based dyes for the better PCE.

  4. Structural Antitumoral Activity Relationships of Synthetic Chalcones

    Directory of Open Access Journals (Sweden)

    Cesar Echeverria

    2009-01-01

    Full Text Available 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 HepG2 cells. The absence of methoxy substituents in the B ring of synthetic 2’-hydroxychalcones, showed the mayor structure-activity pattern along the series.

  5. Structure-property relationship of 3-(4-substituted benzyl)-1,3-diazaspiro[4.4]nonane-2,4-diones as new potentional anticonvulsant agents. An experimental and theoretical study

    Science.gov (United States)

    Lazić, Anita M.; Božić, Bojan Đ.; Vitnik, Vesna D.; Vitnik, Željko J.; Rogan, Jelena R.; Radovanović, Lidija D.; Valentić, Nataša V.; Ušćumlić, Gordana S.

    2017-01-01

    The structure-property relationship of newly synthesized 3-(4-substituted benzyl)-1,3-diazaspiro [4.4]nonane-2,4-diones was studied by experimental and calculated methods. The prepared compounds were characterized by UV-Vis, FT-IR, 1H NMR and 13C NMR spectroscopy and elemental analysis. The crystal structure was elucidated by single-crystal X-ray diffraction. The 3-benzyl-1,3-diazaspiro[4.4]nonane-2,4-dione crystallizes in triclinic P-1 space group, with two crystallographically independent molecules in the asymmetric unit. Cyclopentane ring adopts an envelope conformation. A three-dimensional crystal packing is governed by hydrogen N-H⋯O bonds, numerous C-H⋯O/N and C-H … π interactions between neighboring molecules. Density functional theory (DFT) calculations with B3LYP and M06-2X methods using 6-311++G(d,p) basis set were performed to provide structural and spectroscopic information. Comparisons between experimental and calculated UV-Vis spectral properties suggest that the monomeric form of the investigated spirohydantoins is dominant in all used solvents. The effects of substituents on the absorption spectra of spirohydantoins are interpreted by correlation of absorption frequencies with Hammett equation. The lipophilicities of the investigated molecules were estimated by calculation of their log P values. Some of the spirohydantoins synthesized in this work, exhibit the lipophilicities comparable to the standard medicine anticonvulsant drug Phenytoin. The results obtained in this investigation afford guidelines for the preparation of new derivatives of spirohydantoin as potential anticonvulsant agents and for better understanding the structure-activity relationship.

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

    Science.gov (United States)

    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 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

  7. 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.

  8. Quantitative structure- activity/property relationship approach and its application in food research%定量结构—活性/性质相关研究及其在食品领域的应用

    Institute of Scientific and Technical Information of China (English)

    周如金; 张庆; 邱松山; 黄敏

    2011-01-01

    定量结构—活性/性质相关研究(Quantitative Structure -Activity/Property Relationship,QSAR/ QSPR)描述化合物分子结构与生物活性及理化性质之间的因果关系.通过QSAR/QSPR研究,不仅可以发现并确定对化合物活性/性质起关键影响作用的化合物结构因素,有效指导高效、低毒新型化合物的合成,而且可以对进入环境的数以千万计化学物质的毒性和生物效应的评价提供一个经济、简便的方法.本文概述了定量结构—活性/性质相关原理及其研究方法,从食品抗氧化剂、食品防腐剂、食品风味成分和食品成分安全性评价等方面阐述了定量结构—活性/性质相关研究在食品领域的应用现状,并从推动食品向绿色、安全、营养方向发展,展望了QSAR/QSPR在食品成分的毒性及其致毒机理研究、食用化学品安全性评价以及有效指导新型、低毒食用化学品的开发等方面在食品领域的应用前景.%Quantitative structure - activity/ property relationship (QSAR/QSRR) is an important method to analysis the correlation between structure of molecules and its bioactivity or physical - chemical property. QSAR/QSPR can not only determine the structure which is a key role in activity, property and synthesis of organic compound, but it also provides an economic and brief evaluation of toxicity and the biological effect of hundreds of thousands of compounds in the environment. The principle and research methods of QSAR/QSPR as well as its application situation in the field of food research, such as food antioxidants, food preservatives, food flavoring and food safety evaluation were reviewed. Then the possible applications in food toxicity and its mechanisms, food chemicals safety evaluation, as well as guiding the development of new, safe food chemicals were also prospected.

  9. Structure-Property Relations in Nonferrous Metals

    Science.gov (United States)

    Russell, Alan; Loong Lee, Kok

    2005-05-01

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

  10. Intermetallics structures, properties, and statistics

    CERN Document Server

    Steurer, Walter

    2016-01-01

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

  11. 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.

  12. Effect of Chemical Structure on Molecular Properties of Hyperbranched Polycarbosilanes

    Institute of Scientific and Technical Information of China (English)

    E.Tarabukina; A.Shpyrkov; A.Amirova; E.Tarasova; N.Shumilkina; A.Filippov; A.Muzafarov

    2007-01-01

    1 Results In spite of the increased interest to the synthesis of hyperbranched polymers,there is a lack of studies of conformational properties of their macromolecules.Structural features of hyperbranched polymers are responsible for new properties that distinguish them from linear compounds and open unique possibilities for their applications.The knowledge of the "structure-properties" relationships is of fundamental value,it also can be helpful when developing new technologies and new materials. The g...

  13. The Impact of Pore Structure on Densification Efficiency of 2-D Carbon-Carbon Composites and Its Relationship to Mechanical Properties

    Science.gov (United States)

    2011-03-01

    structural panels, disc brakes , rotors, and beams. One of the biggest problems with both unidirectional and 2-D composite structures is the very low...41  2.2 Analysis Equipment...49  3. Task 1 Results and Analysis ................................................................................ 52  3.1 Water Immersion Results

  14. Do institutions matter in neighbourhood commons governance? A two-stage relationship between diverse property-rights structure and residential public open space (POS quality: Kota Kinabalu and Penampang, Sabah, Malaysia

    Directory of Open Access Journals (Sweden)

    Ling Gabriel Hoh Teck

    2016-02-01

    Full Text Available Despite the existing literature regarding institutional influence ontraditional commons, there is still a comparative dearth of research that theorisesproperty-rights structure and its impact on contemporary commons. This isparticularly true for public open space (POS governance: its management andutilisation and hence its quality, of which underinvestment and overexploitationleads to increasingly negative externalities and outcomes. An interdisciplinarystudy is employed here to depict the relationships of diverse property-rightsstructure attributes – POS title existence, community existence, POS title transfer and POS site handing-over period to local government – with quality ofresidential POS. A cross-sectional survey via direct structured observation witha POS quality audit tool was conducted to collect a randomly stratified sampleof 155 Country Lease (CL POS and entire 22 Native Title (NT POS, from thedistricts of Kota Kinabalu and Penampang, Sabah, respectively. Archival searchand document analysis on data of property-rights attributes were executed aswell. Next, 2-stage Pearson’s Chi-Square ( c2 and Lambda (λ with ProportionalReduction Error feature analyses were performed. Results showed that only thesethree property-rights attributes – title deed existence, community existence andPOS site handing-over period to local government- are significantly associatedwith POS quality at significance level (p≤0.05. It is found that, although POSwith title deed and community’s involvement might not contribute to goodquality, these attributes were likely to provide better quality. On the other hand,it is found that the more recent the POS site handing over to government, thehigher the likelihood of good POS quality and vice versa. Such empirical findingsprima facie infer that: (i current local property-rights structure does matter incontributing to POS condition, particularly the effective management right whichlikely leads to better

  15. Molecular-Level Control of Ciclopirox Olamine Release from Poly(ethylene oxide)-Based Mucoadhesive Buccal Films: Exploration of Structure-Property Relationships with Solid-State NMR.

    Science.gov (United States)

    Urbanova, Martina; Gajdosova, Marketa; Steinhart, Miloš; Vetchy, David; Brus, Jiri

    2016-05-02

    Mucoadhesive buccal films (MBFs) provide an innovative way to facilitate the efficient site-specific delivery of active compounds while simultaneously separating the lesions from the environment of the oral cavity. The structural diversity of these complex multicomponent and mostly multiphase systems as well as an experimental strategy for their structural characterization at molecular scale with atomic resolution were demonstrated using MBFs of ciclopirox olamine (CPX) in a poly(ethylene oxide) (PEO) matrix as a case study. A detailed description of each component of the CPX/PEO films was followed by an analysis of the relationships between each component and the physicochemical properties of the MBFs. Two distinct MBFs were identified by solid-state NMR spectroscopy: (i) at low API (active pharmaceutical ingredient) loading, a nanoheterogeneous solid solution of CPX molecularly dispersed in an amorphous PEO matrix was created; and (ii) at high API loading, a pseudoco-crystalline system containing CPX-2-aminoethanol nanocrystals incorporated into the interlamellar space of a crystalline PEO matrix was revealed. These structural differences were found to be closely related to the mechanical and physicochemical properties of the prepared MBFs. At low API loading, the polymer chains of PEO provided sufficient quantities of binding sites to stabilize the CPX that was molecularly dispersed in the highly amorphous semiflexible polymer matrix. Consequently, the resulting MBFs were soft, with low tensile strength, plasticity, and swelling index, supporting rapid drug release. At high CPX content, however, the active compounds and the polymer chains simultaneously cocrystallized, leaving the CPX to form nanocrystals grown directly inside the spherulites of PEO. Interfacial polymer-drug interactions were thus responsible not only for the considerably enhanced plasticity of the system but also for the exclusive crystallization of CPX in the thermodynamically most stable

  16. Some Structural Properties of SAT

    Institute of Scientific and Technical Information of China (English)

    刘田

    2000-01-01

    The following four conjectures about structural properties of SAT are studied in this paper. (1) SAT ∈ PSPARSE∩NP; (2) SAT ∈ SRTDtt; (3) SAT ∈ PbttAPP; (4) FPSttAT = FPSATlog. It is proved that some pairs of these conjectures imply P = NP, for example, if SAT ∈ PSPARSE∩NP and SAT ∈ PbttAPP, or if SAT ∈ SRTDtt and SAT ∈ PbttAPP, then P = NP. This improves previous results in literature.

  17. 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.

  18. Peptide Bacteriocins--Structure Activity Relationships.

    Science.gov (United States)

    Etayash, Hashem; Azmi, Sarfuddin; Dangeti, Ramana; Kaur, Kamaljit

    2015-01-01

    With the growing concerns in the scientific and health communities over increasing levels of antibiotic resistance, antimicrobial peptide bacteriocins have emerged as promising alternatives to conventional small molecule antibiotics. A substantial attention has recently focused on the utilization of bacteriocins in food preservation and health safety. Despite the fact that a large number of bacteriocins have been reported, only a few have been fully characterized and structurally elucidated. Since knowledge of the molecular structure is a key for understanding the mechanism of action and therapeutic effects of peptide, we centered our focus in this review on the structure-activity relationships of bacteriocins with a particular focus in seven bacteriocins, namely, nisin, microcin J25, microcin B17, microcin C, leucocin A, sakacin P, and pediocin PA-1. Significant structural changes responsible for the altered activity of the recent bacteriocin analogues are discussed here.

  19. The Origin of Sulfur Tolerance in Supported Platinum Catalysts: The Relationship between Structural and Catalytic Properties in Acidic and Alkaline Pt/LTL.

    NARCIS (Netherlands)

    Koningsberger, D.C.; Miller, J.T.

    1996-01-01

    The reactivity, structure, and sulfur tolerance is compared for platinum supported on acidic and alkaline LTL zeolite. In the absence of sulfur, EXAFS spectroscopy indicates that small metallic platinum particles of approximately 6 to 14 atoms/cluster are present. The TOF for neopentane hydrogenolys

  20. Structure and Structure-activity Relationship of Functional Organic Molecules

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    @@ Research theme The group is made up of junior scientists from the State Key Laboratory of Elemento-organic Chemistry, Nankai University.The scientists focus their studis on the structure and structure-activity relationship of functional organic molecules not only because it has been the basis of their research, but also because the functional study of organic compounds is now a major scientific issue for organic chemists around the world.

  1. Structural and Spectral Properties of Deterministic Aperiodic Optical Structures

    Directory of Open Access Journals (Sweden)

    Luca Dal Negro

    2016-12-01

    Full Text Available In this comprehensive paper we have addressed structure-property relationships in a number of representative systems with periodic, random, quasi-periodic and deterministic aperiodic geometry using the interdisciplinary methods of spatial point pattern analysis and spectral graph theory as well as the rigorous Green’s matrix method, which provides access to the electromagnetic scattering behavior and spectral fluctuations (distributions of complex eigenvalues as well as of their level spacing of deterministic aperiodic optical media for the first time.

  2. 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.

  3. 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

  4. Structure-property relationships of mullite-SiC-Al{sub 2}O{sub 3}–ZrO{sub 2} composites developed during carbothermal reduction of aluminosilicate minerals

    Energy Technology Data Exchange (ETDEWEB)

    Seifollahzadeh, P., E-mail: Pseifollahzadeh.mat@stu.yazd.ac.ir; Kalantar, M.; Ghasemi, S.S.

    2015-10-25

    Evolution of SiC and ZrO{sub 2} in the matrix of Al{sub 2}O{sub 3} or mullite have been reported to enhance a higher toughness, good thermal shock resistance (lowering thermal expansion and improving thermal conductivity) and improved creep resistance of composite materials. In this study, the structure-property relationships of mullite-Al{sub 2}O{sub 3} matrix composites have been investigated in conjunction with the evolution of reinforcing phases such as SiC–ZrO{sub 2} by an economical heat treatment process called carbothermal reduction of inorganic minerals (Kaolinite, Andalusite, Zircon). The influence of starting materials in relation with the variation in molar ratio of C/SiO{sub 2} on the phase composition, microstructures, physical and mechanical properties have been studied. Light microscopy has been supplemented with scanning electron microscopy, XRD analysis, differential thermal and thermal gravity analysis to follow the structure-property relationships. The experimental results show that with increasing of C/SiO{sub 2} ratio in starting materials, very fine SiC whiskers have been formed in the microstructures. Moreover, the densification and strength are considerable higher for ZrO{sub 2} + SiC containing composites in comparison to that of only SiC added ones. Furthermore, it has been found that the appropriate ratio of C/SiO{sub 2} with the associated firing temperature to develop a higher densification and SiC crystallization have been related to the 3.5, 1550 °C for kaolinite, 3.5, 1450 °C for zircon and 5.5, 1600 °C for andalusite containing composite samples, respectively. - Highlights: • In-situ formation of SiC whiskers in matrix of alumina + mullite composites. • Advantage of availability, abundance and economical for starting materials. • Lack of environmental problems in comparable of utilization of whiskers directly. • A mixture of coke and alumina as a protective layer instead of inert atmosphere. • Fabrication of advanced

  5. 南堡3号构造带古近系储层特征与四性关系研究%Reservoir Characteristics and Four-Property Relationship of Paleogene Reservoir in Nanpu 3rd Structure Belt

    Institute of Scientific and Technical Information of China (English)

    牛海瑞; 杨少春; 赵晓东; 陈潇; 何妮茜

    2015-01-01

    The third structure belt in Nanpu oilfield is located in the beach area where most of the wells are brine mud wells. The complex geological conditions and the characterization of high salinity and potassium lead to the difficulty of lithology identification. Based on the logging data standardization ,this paper makes full use of well logging data,mud logging data,rock thin section,core analytical data and so on to study on the reservoir characteristics and four-property relationship of Paleogene reservoir. and set up the four-property relationship model of lithology , poroperm characteristics,petroliferous properties and electric properties. The results show that Paleogene reservoir has middle to low porosity and middle permeability. The lithology is mainly medium sandstone,inequigranular sandstone and conglomerate. Along with the lithology change from fine to coarse,the reservoir poroperm characteristics are getting better,and Oil-bearing grade getting higher. Porosity and permeability are exponential correlation while the porosity and acoustic time are simple linear relationship. The study of reservoir four-property relationship is the foundation of well logging interpretation and reservoir evaluation which will provide references for the continue development of oil field.%南堡油田3号构造带地处滩海,具有高盐富钾的地质特点且基本为盐水泥浆基液钻井,增加了储层评价的难度。在测井资料标准化的基础上,综合利用测井、录井、薄片和岩心分析化验等资料,对古近系储层开展储层特征和四性关系研究,建立了储层岩性、物性、电性及含油气性之间的关系模型。研究表明,古近系属于中低孔中渗储层,岩性以中砂岩、不等粒砂岩和砂砾岩为主。随岩性由细变粗,储层物性变好,含油级别变高。孔隙度与渗透率呈指数相关,与声波时差呈较简单线性关系。储层四性关系研究是研究区开展测井解

  6. Materials science in microelectronics I the relationships between thin film processing and structure

    CERN Document Server

    Machlin, Eugene

    2005-01-01

    Thin films play a key role in the material science of microelectronics, and the subject matter of thin-films divides naturally into two headings: processing / structure relationship, and structure / properties relationship.The first volume of Materials Science in Microelectronics focuses on the first relationship - that between processing and the structure of the thin-film. The state of the thin film's surface during the period that one monolayer exists - before being buried in the next layer - determines the ultimate structure of the thin film, and thus its properties. This

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

    Science.gov (United States)

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

    2017-03-01

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

  8. 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.

  9. Structural relationships and vasorelaxant activity of monoterpenes

    Directory of Open Access Journals (Sweden)

    Cardoso Lima Tamires

    2012-09-01

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

  10. 脂肪族含氧有机物沸点的定量构效关系%Quantitative structure-property relationship of normal boiling point of aliphatic oxygen-containing organic compounds

    Institute of Scientific and Technical Information of China (English)

    刘万强; 曹晨忠

    2012-01-01

    The descriptors of polarizability effect index (PEI),the number of effective carbon (Nc,e(f)> the differences in PEI and Nc,eff between the branching chain and straight chain isomers,SPEI and δ Nc,eff,are derived from molecular structure. The quantitative structure-property relationships (QSPRs) between these descriptors and boiling points of 520 aliphatic alcohols,ethers,aldehydes,ketones,acids,and esters were obtained separately. The QSPRs between these descriptors and boiling points were developed for 520 aliphatic oxygen-containing organic compounds by best subsets regression method. For the training set,the correlation coefficient R2 is 0. 9946 and the standard deviation GO is 6. 70 K. For the test set,R2 is 0. 9857 and s is 6. 10 K. The average relative error is 1. 19%. According to the regression equation,the influences of the number of effective carbon of alkyl,the role of functional groups and their interaction on the boiling point were analyzed. These results showed a good correlation between the boiling points of organic compounds and these descriptors derived from PEI for aliphatic alcohols,ethers,aldehydes,ketones,acids,and esters.

  11. Structure-cytotoxicity relationships for dietary flavonoids

    DEFF Research Database (Denmark)

    Breinholt, V.; Dragsted, L.O.

    1998-01-01

    The cytotoxicity of a large series of dietary flavonoids was tested in a non-tumorigenic mouse and two human cancer cell lines, using the neutral red dye exclusion assay. All compounds tested exhibited a concentration-dependent cytotoxic action in the employed cell lines. The relative cytotoxicity...... of the flavonoids, however, Tvas found to vary greatly among the different cell Lines. With a few exceptions, the investigated flavonoids were more cytotoxic to the human cancer cell lines, than the mouse cell line. The differences in cytotoxicity were accounted for in part by differences in cellular uptake...... and metabolic capacity among the different cell types. In 3T3 cells fairly consistent structure-cytotoxicity relationships were found. The most cytotoxic structures tested in 3T3 cells were flavonoids with adjacent 3',4' hydroxy groups on the B-ring, such as luteolin, quercetin, myricetin, fisetin, eriodictyol...

  12. Familial identification: population structure and relationship distinguishability.

    Directory of Open Access Journals (Sweden)

    Rori V Rohlfs

    2012-02-01

    Full Text Available With the expansion of offender/arrestee DNA profile databases, genetic forensic identification has become commonplace in the United States criminal justice system. Implementation of familial searching has been proposed to extend forensic identification to family members of individuals with profiles in offender/arrestee DNA databases. In familial searching, a partial genetic profile match between a database entrant and a crime scene sample is used to implicate genetic relatives of the database entrant as potential sources of the crime scene sample. In addition to concerns regarding civil liberties, familial searching poses unanswered statistical questions. In this study, we define confidence intervals on estimated likelihood ratios for familial identification. Using these confidence intervals, we consider familial searching in a structured population. We show that relatives and unrelated individuals from population samples with lower gene diversity over the loci considered are less distinguishable. We also consider cases where the most appropriate population sample for individuals considered is unknown. We find that as a less appropriate population sample, and thus allele frequency distribution, is assumed, relatives and unrelated individuals become more difficult to distinguish. In addition, we show that relationship distinguishability increases with the number of markers considered, but decreases for more distant genetic familial relationships. All of these results indicate that caution is warranted in the application of familial searching in structured populations, such as in the United States.

  13. Familial identification: population structure and relationship distinguishability.

    Science.gov (United States)

    Rohlfs, Rori V; Fullerton, Stephanie Malia; Weir, Bruce S

    2012-02-01

    With the expansion of offender/arrestee DNA profile databases, genetic forensic identification has become commonplace in the United States criminal justice system. Implementation of familial searching has been proposed to extend forensic identification to family members of individuals with profiles in offender/arrestee DNA databases. In familial searching, a partial genetic profile match between a database entrant and a crime scene sample is used to implicate genetic relatives of the database entrant as potential sources of the crime scene sample. In addition to concerns regarding civil liberties, familial searching poses unanswered statistical questions. In this study, we define confidence intervals on estimated likelihood ratios for familial identification. Using these confidence intervals, we consider familial searching in a structured population. We show that relatives and unrelated individuals from population samples with lower gene diversity over the loci considered are less distinguishable. We also consider cases where the most appropriate population sample for individuals considered is unknown. We find that as a less appropriate population sample, and thus allele frequency distribution, is assumed, relatives and unrelated individuals become more difficult to distinguish. In addition, we show that relationship distinguishability increases with the number of markers considered, but decreases for more distant genetic familial relationships. All of these results indicate that caution is warranted in the application of familial searching in structured populations, such as in the United States.

  14. 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.

  15. Structural Relationships and Vasorelaxant Activity of Monoterpenes

    Directory of Open Access Journals (Sweden)

    Tamires Cardoso Lima

    2012-09-01

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

  16. Structure-Property Relationships in Intercalated Graphite.

    Science.gov (United States)

    1984-10-15

    have been carried out on well staged KHg -GIC, SbCI5-GIC samples and on partly desorbed Br 2-GIC samples.(#39) All theK measuement.have been made using...multiphase coexistence in alliH metal GICo.(#1) For the KHg -G1C and SbCls-GIC system, the staging perfection has been studied using c-axis lattice fringing...observed for both in-plane and c-as fringes. For the case of the stage I KHg -GIC, three different commensurate phases have been identified from the lattice

  17. Structure-Property Relationships in Intercalated Graphite.

    Science.gov (United States)

    1985-07-10

    and . vermicular graphite host materials. Detailed TEM results show that the glassy phase is induced by the electron beam irradiation through a...sample thickness could be related to the observation of a glass phase, experiments were carried out using both kish and vermicular graphite host materials

  18. Structure-properties relationships in polymeric fibres

    NARCIS (Netherlands)

    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

  19. Structure-activity relationship studies of argiotoxins

    DEFF Research Database (Denmark)

    Poulsen, Mette H; Lucas, Simon; Bach, Tinna B;

    2013-01-01

    Argiotoxin-636 (ArgTX-636), a natural product from the spider Argiope lobata, is a potent but nonselective open-channel blocker of ionotropic glutamate (iGlu) receptors. Here, three series of analogues were designed to exploit selectivity among iGlu receptors, taking advantage of a recently devel......, respectively. Thus, the first structure-activity relationship study of ArgTX-636 has been carried out and has provided lead compounds for probing the ion channel region of iGlu receptors....... developed solid-phase synthetic methodology for the synthesis of ArgTX-636 and analogues. Initially, the importance of secondary amino groups in the polyamine chain was studied by the synthesis of systematically modified ArgTX-636 analogues, which were evaluated for pharmacological activity at NMDA and AMPA...

  20. The Relationship between Polarographic Reduction Potentials and Discharge Properties of Disperse Dyes

    Institute of Scientific and Technical Information of China (English)

    LONG Jia-jie; CHENG Wan-li; WANG Hui-zhen; TANG Ren-cheng; FAN Bing-xian

    2005-01-01

    The half-wave potentials of disperse dyes with different structures are measured, the relationship between half-wave potentials and their discharge properties is discussed, then their effect factors are studied, such as the chemical structure types and substituents of disperse dyes and technological parameters. The results indicate that the halfwave potentials of disperse dyes when reduced could be used to characterize their reducing and discharge properties.

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

    Science.gov (United States)

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

    2014-08-18

    The creation of organic dyes with excellent high power conversion efficiency (PCE) is important for the further improvement of dye-sensitized solar cells. We wish to describe the rapid synthesis of a 112-membered donor-π-acceptor dye library by a one-pot procedure, evaluation of PCEs, and elucidation of structure-property relationships. No obvious correlations between ε, and the η were observed, whereas the HOMO and LUMO levels of the dyes were critical for η. The dyes with a more positive E(HOMO), and with an E(LUMO)<-0.80 V, exerted higher PCEs. The proper driving forces were crucial for a high J(sc), and it was the most important parameter for a high η. The above criteria of E(HOMO) and E(LUMO) should be useful for creating high PCE dyes; nevertheless, that was not sufficient for identifying the best combination of donor, π, and acceptor blocks. Combinatorial synthesis and evaluation was important for identifying the best dye.

  2. An investigation of the structure-property relationships in ionic polymer polymer composites (IP2Cs) manufactured by polymerization in situ of PEDOT/PSS on Nafion®117

    Science.gov (United States)

    Di Pasquale, G.; Graziani, S.; Messina, F. G.; Pollicino, A.; Puglisi, R.; Umana, E.

    2014-03-01

    Ionic polymer polymer composites (IP2Cs) are all-organic electroactive polymers (EAPs) that show sensing and actuation capabilities when a deformation or a voltage is applied, respectively. They are fabricated starting from an ionic polymer coated on both sides with a conducting polymer as electrode element. In this work, poly(3,4-ethylendioxytiophene)-poly-(styrenesulfonate) (PEDOT/PSS) has been polymerized directly on Nafion®117 membrane and devices have been manufactured varying the polymerization time. Water and ethylene glycol (EG) have been used as solvents. The obtained IP2Cs have been characterized using thermal and mechanical analyses and electromechanically tested. The results have shown that in IP2Cs manufactured by polymerization in situ the PEDOT/PSS layer adheres very strongly on the Nafion®117 film, improving the possibility of rehydrating the devices after use. Moreover, taking into account that the different polymerization times influence the uniformity of the surface of the organic electrode and, consequently, both device stiffness and electrode conductivity, the structure-property relationships of the obtained devices have been investigated. The influence of the different solvents inside the devices has also been studied when IP2Cs have been used as actuators or sensors. Reported results show that it is possible to modulate the performances of IP2Cs by varying some manufacture parameters and the solvent.

  3. Carbon fibers: precursor systems, processing, structure, and properties.

    Science.gov (United States)

    Frank, Erik; Steudle, Lisa M; Ingildeev, Denis; Spörl, Johanna M; Buchmeiser, Michael R

    2014-05-19

    This Review gives an overview of precursor systems, their processing, and the final precursor-dependent structure of carbon fibers (CFs) including new developments in precursor systems for low-cost CFs. The following CF precursor systems are discussed: poly(acrylonitrile)-based copolymers, pitch, cellulose, lignin, poly(ethylene), and new synthetic polymeric precursors for high-end CFs. In addition, structure-property relationships and the different models for describing both the structure and morphology of CFs will be presented.

  4. 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.

  5. Structure-function relationship in novel polyphenolics

    Science.gov (United States)

    Banerjee, Sukanta

    The synthesis, properties and applications of hydroxyaromatic polymers, synthesized enzymatically in AOT/Water/Isooctane water-in-oil microemulsion is the subject of this dissertation. The enzymatic polymerization in such microstructured media furnishes the final polymer product with the unusual morphology of interconnected microspheres. Fundamental characterization of the nature of interaction of a model polymer, poly(4-ethylphenol), with the surfactant AOT, as well as various solvents was carried out to elucidate the molecular mechanism of the morphology development. From an applied perspective, presynthesized poly(4-ethylphenol) was precipitated using AOT/Water/Isooctane water-in-oil microemulsion as the non-solvent to give spherical microparticles. Of specific interest was the encapsulation of macromolecules and nanoparticles initially solubilized in the water droplets by the precipitating polymer matrix. This technique was utilized to synthesize catalytically active and superparamagnetic microspheres, containing entrapped enzyme and nanoparticulate ferrites, respectively. The enzymatically synthesized polymers possess a fully aromatic backbone and hence are expected to have unique pi conjugated structure. On the basis of this hypothesis several conjugated luminescent polymers were synthesized using 2-naphthol and 2,6-dihydroxynaphthalene as the starting monomer. Chemical tuning of the emission properties of these polymers were achieved by copolymerization with 4-ethylphenol which is not a luminescent molecule. Addition of 2,6-dihydroxynaphthalene in dry reversed micellar solutions of AOT induced a dramatic phase transition to a clear luminescent organogel. Hydrogen bonding interaction between the hydroxyl groups and the head group of AOT form the basis of such gels. The microstructure of the gel was probed using NMR and FTIR spectroscopy. Finally, thiol group containing polymers were synthesized to bind nanoparticulate CdS, forming novel photoresponsive

  6. Cellulose nanomaterials review: structure, properties and nanocomposites

    OpenAIRE

    Moon, Robert J.; Martini, Ashlie; Nairn, John; Simonsen, John; Youngblood, Jeffrey

    2011-01-01

    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction...

  7. Amylopectin molecular structure in relation to physicochemical properties of quinoa starch.

    Science.gov (United States)

    Li, Guantian; Zhu, Fan

    2017-05-15

    Structure-function relationships of starch components remain a subject of research interest. Quinoa starch has very small granules (∼2μm) with unique properties. In this study, nine quinoa starches varied greatly in composition, structure, and physicochemical properties were selected for the analysis of structure-function relationships. Pearson correlation analysis revealed that the properties related to gelatinization such as swelling power, water solubility index, crystallinity, pasting, and thermal properties are much affected by the amylopectin chain profile and amylose content. The parameters of gel texture and amylose leaching are much related to amylopectin internal structure. Other properties such as enzyme susceptibility and particle size distribution are also strongly correlated with starch composition and amylopectin structure. Interesting findings indicate the importance of amylopectin internal structure and individual unit chain profile in determining the physicochemical properties of starch. This work highlights some relationships among composition, amylopectin structure and physicochemical properties of quinoa starch.

  8. Structure-function relationships in calpains.

    Science.gov (United States)

    Campbell, Robert L; Davies, Peter L

    2012-11-01

    Calpains are a family of complex multi-domain intracellular enzymes that share a calcium-dependent cysteine protease core. These are not degradative enzymes, but instead carry out limited cleavage of target proteins in response to calcium signalling. Selective cutting of cytoskeletal proteins to facilitate cell migration is one such function. The two most abundant and extensively studied members of this family in mammals, calpains 1 and 2, are heterodimers of an isoform-specific 80 kDa large subunit and a common 28 kDa small subunit. Structures of calpain-2, both Ca2+-free and bound to calpastatin in the activated Ca2+-bound state, have provided a wealth of information about the enzyme's structure-function relationships and activation. The main association between the subunits is the pairing of their C-terminal penta-EF-hand domains through extensive intimate hydrophobic contacts. A lesser contact is made between the N-terminal anchor helix of the large subunit and the penta-EF-hand domain of the small subunit. Up to ten Ca2+ ions are co-operatively bound during activation. The anchor helix is released and individual domains change their positions relative to each other to properly align the active site. Because calpains 1 and 2 require ~30 and ~350 μM Ca2+ ions for half-maximal activation respectively, it has long been argued that autoproteolysis, subunit dissociation, post-translational modifications or auxiliary proteins are needed to activate the enzymes in the cell, where Ca2+ levels are in the nanomolar range. In the absence of robust support for these mechanisms, it is possible that under normal conditions calpains are transiently activated by high Ca2+ concentrations in the microenvironment of a Ca2+ influx, and then return to an inactive state ready for reactivation.

  9. Structure/function relationships in cellulolytic enzymes

    Institute of Scientific and Technical Information of China (English)

    Marc Claeyssens

    2004-01-01

    @@ Cellulose and hemicellulose (mostly xylan), together with lignin, are the major polymeric constituents of plant cell walls and from the largest reservoir of fixed carbon in nature. The enzymatic hydrolysis of polymeric substances by extracellular enzymes, such as cellulases, hemicellulases and laccases, is preferred to chemical depolymerisation to avoid the production of toxic by-products and waste that are expensive to treat. The monosaccharides released through enzymatic hydrolysis can subsequently be microbially converted to commercial commodities, such as bio-ethanol (fuel extender) or microbial protein as feed supplements. The individual depolymerisering enzymes used, such as cellulases,xylanases and laccases, also have industrial application in (i) biobleaching in the paper and pulp industry, (ii) improvement of animal feed (poultry and ruminants) digestibility in feed industries, and (iii) dough rheology and bread volume in the baking process, and beer viscosity and filtration velocity during brewing. The cloning of the genes, coding for several xylan degrading enzymes, and their expression in Baker' s yeast (Saccharomyces cerevisiae) and filamentous fungi (Aspergillus species)opened the possibility to study the pure enzymes, without contaminating activity.Trichoderma reesei produces several of these enzymes and detailed information on their specificity,synergies and structure/activity relationships is known. An overview will be presented.

  10. Relationship between pore structure and compressive strength of concrete: Experiments and statistical modeling

    Indian Academy of Sciences (India)

    J BU; Z TIAN

    2016-03-01

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and subjected to static compressive tests. The pore structure features such as porosity, pore size distribution are extracted using mercury intrusion porosimetry technique. A statistical model is developed to relate thecompressive strength to relevant pore structure features.

  11. 部分有机锡化合物定量结构-性质关系研究%Study of selected organotin compounds′ quantitative structure-property relationship

    Institute of Scientific and Technical Information of China (English)

    全燮; 陈景文; 王帅杰; 陈硕; 薛大明; 赵雅芝

    2001-01-01

    应用偏最小二乘(PLS)算法,采用量子化学PM3算法计算得到的量子化学参数,得到了部分有机锡化合物的正辛醇-水分配系数(logKow)的定量结构-性质关系(QSPR)模型.应用该模型,可以对其他有机锡分子的log Kow进行初步预测.影响有机锡分子log Kow大小的主要因素是分子的大小;相对分子质量较大的分子,其log Kow值较大.此外,分子最高占据轨道能(Ehomo)对有机锡化合物log Kow的大小也有一定的影响;Ehomo较大的分子,其log Kow值也较大.%By means of Partial Least Squares (PLS) method, based on thequantum chemical descriptors computed from PM3 Hamiltonian, quantitative structure-property relationship (QSPR) on logarithm of n-octanol-water partition coefficient (log Kow) of selected organotin compounds was obtained. The QSPR obtained c an be used for the initial prediction of other organotin compounds. The size of the molecules is a main factor affecting the log Kow. Organotin compounds with large molecular weight usually have great log Kow values. In addition, the effect of the energy of the highest occupied molecular orbital (Ehomo) on the log Kow cannot be neglected. Organotin compounds with large Ehomo tend to have great log Kow values.

  12. Quantitative Structure-Property Relationship of the Critical Micelle Concentration of Different Classes of Surfactants%多种类表面活性剂临界胶束浓度定量构效关系

    Institute of Scientific and Technical Information of China (English)

    朱志臣; 王强; 贾青竹; 汤红梅; 马沛生

    2013-01-01

      表面活性剂的临界胶束浓度(CMC)是个非常重要的物质特性参数, CMC在研究表面活性剂的工业应用和生物利用方面发挥着关键作用.本工作提出了一个新的拓扑指数—扩展距离矩阵,建立了一个稳定的构效关系模型,并对175种表面活性剂的临界胶束浓度进行了计算预测.结果表明,基于新的拓扑指数建立的构效关系模型计算临界胶束浓度能给出稳定可靠的预测结果,其预测结果相关性系数R2(training set)=0.9295,平均相对偏差ARD(training set)=8.20%, R2(testing set)=0.9257, ARD(testing set)=6.76%.与文献中模型预测结果的对比表明,本工作在稳定性和可靠性上均有显著改善.%Critical micel e concentration (CMC) is one of the most useful parameters for the characterization of surfactants; thus, CMC plays an important role in the investigation of the surfactantsʹproperties for industrial applications and biological utilizations. The fol owing study presents a stable and accurate structure-property relationship model for the prediction of CMC for a diverse set of 175 surfactants using a new topological index, the extended distance matrix. Research indicates that the new model based on this topological index is very efficient and provides satisfactory results. The high-quality prediction model is evidenced by an R2 (square correlation coefficient) value of 0.9295 and an average relative difference (ARD) value of 8.20% for the training set, an R2 value of 0.9257 and an ARD value of 6.76% for the testing set. Comparison results with reference models demonstrate that this new method based on the topological index results in significant improvements, both in accuracy and stability for predicting CMC of surfactants.

  13. Family Structures, Relationships, and Housing Recovery Decisions after Hurricane Sandy

    Directory of Open Access Journals (Sweden)

    Ali Nejat

    2016-04-01

    Full Text Available Understanding of the recovery phase of a disaster cycle is still in its infancy. Recent major disasters such as Hurricane Sandy have revealed the inability of existing policies and planning to promptly restore infrastructure, residential properties, and commercial activities in affected communities. In this setting, a thorough grasp of housing recovery decisions can lead to effective post-disaster planning by policyholders and public officials. The objective of this research is to integrate vignette and survey design to study how family bonds affected rebuilding/relocating decisions after Hurricane Sandy. Multinomial logistic regression was used to investigate respondents’ family structures before Sandy and explore whether their relationships with family members changed after Sandy. The study also explores the effect of the aforementioned relationship and its changes on households’ plans to either rebuild/repair their homes or relocate. These results were compared to another multinomial logistic regression which was applied to examine the impact of familial bonds on respondents’ suggestions to a vignette family concerning rebuilding and relocating after a hurricane similar to Sandy. Results indicate that respondents who lived with family members before Sandy were less likely to plan for relocating than those who lived alone. A more detailed examination shows that this effect was driven by those who improved their relationships with family members; those who did not improve their family relationships were not significantly different from those who lived alone, when it came to rebuilding/relocation planning. Those who improved their relationships with family members were also less likely to suggest that the vignette family relocate. This study supports the general hypothesis that family bonds reduce the desire to relocate, and provides empirical evidence that family mechanisms are important for the rebuilding/relocating decision

  14. Crosslinking-property relationships in PMR polyimide composites. I

    Science.gov (United States)

    Pater, R. H.; Whitley, K.; Morgan, C.; Chang, A.

    1987-01-01

    The thermooxidatively-induced crosslinking/ physical and mechanical property relationships of graphite fiber-reinforced PMR polyimide-matrix composites were studied during isothermal exposure of the composite specimens at 288 C in air for periods of up to 5000 hr. The crosslinking densities due to this treatment were estimated on the basis of the kinetic theory of rubber elasticity and shifts in the glass transition temperature T(g). Several linear relationships are noted between crosslink density and physical and mechanical properties: T(g), initial weight loss, and elevated temperature interlaminar shear strength increase with crosslink density, while initial moisture absorption decreases. After achieving the highest crosslink density, several of the composite properties begin to decrease from their maximum values.

  15. Relationship of quantitative structure and pharmacokinetics in fluoroquinolone antibacterials

    Institute of Scientific and Technical Information of China (English)

    Die Cheng; Wei-Ren Xu; Chang-Xiao Liu

    2007-01-01

    AIM: To study the relationship between quantitative structure and pharmacokinetics (QSPkR) of fluoroquinolone antibacterials.METHODS: The pharmacokinetic (PK) parameters of oral fluoroquinolones were collected from the literature. These pharmacokinetic data were averaged, 19 compounds were used as the training set, and 3 served as the test set. Genetic function approximation (GFA)module of Cerius2 software was used in QSPkR analysis.RESULTS: A small volume and large polarizability and surface area of substituents at C-7 contribute to a large area under the curve (AUC) for fluoroquinolones. Large polarizability and small volume of substituents at N-1 contribute to a long half life elimination.CONCLUSION: QSPkR models can contribute to some fluoroquinolones antibacterials with excellent pharmacokinetic properties.

  16. Cellulose nanomaterials review: structure, properties and nanocomposites.

    Science.gov (United States)

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

    2011-07-01

    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

  17. Relationship between protein structure and geometrical constraints

    DEFF Research Database (Denmark)

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

    1996-01-01

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

  18. Relationship between protein structure and geometrical constrains

    DEFF Research Database (Denmark)

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

    1996-01-01

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

  19. Structure and properties of small sodium clusters

    DEFF Research Database (Denmark)

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

    2002-01-01

    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......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...

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

    Directory of Open Access Journals (Sweden)

    B. Geetha Priyadarshini

    2016-07-01

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

  1. Study about inclusion relationships and integral preserving properties

    Directory of Open Access Journals (Sweden)

    Imran Faisal

    2012-12-01

    Full Text Available The object of the present paper is to investigate a family of integral operators defined on the space of meromorphic functions. By making use of these novel integral operators, we introduce and investigate several new subclasses of starlike, convex, close-to-convex, and quasi-convex meromorphic functions. In particular, we establish some inclusion relationships associated with the aforementioned integral operators. Several interesting integral-preserving properties are also considered.

  2. 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...

  3. CASS Ferrite and Grain Structure Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Ruud, Clayton O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ramuhalli, Pradeep [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meyer, Ryan M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Diaz, Aaron A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-13

    This document summarizes the results of research conducted at Pacific Northwest National Laboratory (PNNL) to determine whether, based on experimental measurements, a correlation existed between grain structure in cast austenitic stainless steel (CASS) piping and ferrite content of the casting alloy. The motivation for this research lies in the fact that ultrasonic testing (UT) is strongly influenced by CASS grain structure; knowledge of this grain structure may help improve the ability to interpret UT responses, thereby improving the overall reliability of UT inspections of CASS components.

  4. Protein tyrosine phosphatases: structure-function relationships.

    Science.gov (United States)

    Tabernero, Lydia; Aricescu, A Radu; Jones, E Yvonne; Szedlacsek, Stefan E

    2008-03-01

    Structural analysis of protein tyrosine phosphatases (PTPs) has expanded considerably in the last several years, producing more than 200 structures in this class of enzymes (from 35 different proteins and their complexes with ligands). The small-medium size of the catalytic domain of approximately 280 residues plus a very compact fold makes it amenable to cloning and overexpression in bacterial systems thus facilitating crystallographic analysis. The low molecular weight PTPs being even smaller, approximately 150 residues, are also perfect targets for NMR analysis. The availability of different structures and complexes of PTPs with substrates and inhibitors has provided a wealth of information with profound effects in the way we understand their biological functions. Developments in mammalian expression technology recently led to the first crystal structure of a receptor-like PTP extracellular region. Altogether, the PTP structural work significantly advanced our knowledge regarding the architecture, regulation and substrate specificity of these enzymes. In this review, we compile the most prominent structural traits that characterize PTPs and their complexes with ligands. We discuss how the data can be used to design further functional experiments and as a basis for drug design given that many PTPs are now considered strategic therapeutic targets for human diseases such as diabetes and cancer.

  5. The structural acoustic properties of stiffened shells

    DEFF Research Database (Denmark)

    Luan, Yu

    2008-01-01

    . 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....

  6. 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.

  7. Autoclave foam concrete: Structure and properties

    Science.gov (United States)

    Mestnikov, Alexei; Semenov, Semen; Strokova, Valeria; Nelubova, Viktoria

    2016-01-01

    This paper describes the technology and properties of autoclaved foam concrete taking into account practical experience and laboratory studies. The results of study of raw materials and analysis of structure and properties of foam-concrete before and after autoclave treatment are basic in this work. Experimental studies of structure and properties of foam concrete are carried out according to up-to-date methods and equipment on the base of the shared knowledge centers. Results of experimental studies give a deep understanding of properties of raw materials, possible changes and new formations in inner layers of porous material providing the improvement of constructional and operational properties of autoclaved foam concrete. Principal directions of technology enhancement as well as developing of production of autoclave foam concretes under cold-weather conditions in Russia climate are justified.

  8. Structure and Properties of Compressed Borate Glasses

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauer, U.; Behrens, H.;

    in a series of borate glasses. Upon isostatic compression, NMR experiments show that the fraction of tetrahedral boron increases, leading to an overall decrease of the molar volume of the network. We correlate these structural changes with changes in elastic moduli from Brillouin scattering experiments......While the influence of thermal history on the structure and properties of glasses has been thoroughly studied in the past century, the influence of pressure history has received considerably less attention. In this study, we investigate the pressure-induced changes in structure and properties...

  9. STRUCTURAL AND THERMOPHYSICAL PROPERTIES OF HARDENING CONCRETE

    Directory of Open Access Journals (Sweden)

    L. Krasulina

    2012-01-01

    Full Text Available Structural and thermophysical properties of thermally treated concrete have been studied in the paper. The paper demonstrates regularities of changes in structural and thermophysical properties of concrete during heat treatment process. It is established that stabilization of coefficient values for heat- and temperature conductivity of concrete corresponds to completion of the process pertaining to intensive formation of the material pore structure and indicates the possibility of transition from the stage of isothermal extraction to the stage of temperature decrease. The obtained results are confirmed by studies of strength growth kinetics of concrete samples.

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

    Science.gov (United States)

    Bindel, Thomas H.

    2008-01-01

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

  11. 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.

  12. Investigating Supervisory Relationships and Therapeutic Alliances Using Structural Equation Modeling

    Science.gov (United States)

    DePue, Mary Kristina; Lambie, Glenn W.; Liu, Ren; Gonzalez, Jessica

    2016-01-01

    The authors used structural equation modeling to examine the contribution of supervisees' supervisory relationship levels to therapeutic alliance (TA) scores with their clients in practicum. Results showed that supervisory relationship scores positively contributed to the TA. Client and counselor ratings of the TA also differed.

  13. Comparative genomics of the relationship between gene structure and expression

    NARCIS (Netherlands)

    Ren, X.

    2006-01-01

    The relationship between the structure of genes and their expression is a relatively new aspect of genome organization and regulation. With more genome sequences and expression data becoming available, bioinformatics approaches can help the further elucidation of the relationships between gene struc

  14. Structure-activity relationships of bumetanide derivatives

    DEFF Research Database (Denmark)

    Pedersen, Kasper Lykke; Töllner, Kathrin; Römermann, Kerstin;

    2015-01-01

    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 effects of bumetanide derivatives on NKCC2 are not available. EXPERIMENTAL APPROACH: In this study...

  15. Structure-Property Relationship for the Pharmacological and Toxicological Activity of Heterocyclic Compounds%多种类杂环化合物的药理和毒理活性系数构效关系

    Institute of Scientific and Technical Information of China (English)

    朱志臣; 王强; 贾青竹; 夏淑倩; 马沛生

    2014-01-01

    Heterocyclic molecules play a crucial role in health care and in pharmaceutical drug design. A large number of drugs used in Western medical practice are heterocyclic molecules. In this study, a set of norm indexes of the extended distance matrix are proposed. From these a stable and accurate structure-property relationship model was developed for the prediction of the aryl hydrocarbon receptor binding affinity (pEC50) of dibenzofurans and the mutagenic potency (lnR) of aromatic and heteroaromatic amines. Our results indicate that the new model, based on these norm indexes, provides very satisfactory results, and that the average absolute differences for pEC50 prediction and lnR prediction were 0.403 and 0.702 with r2 (square correlation coefficient) values of 0.876 and 0.779, respectively. A comparison of these results with other methods demonstrates that our method, based only on the same mathematical model, performed better in terms of both accuracy and stability.%杂环类化合物在卫生保健和药物分子设计领域发挥关键作用,在西药中占有重要地位.本工作针对扩展距离矩阵提出了一组范数指数,基于扩展距离矩阵的范数指数构建了一个新的构效关系模型,并对杂环类化合物二苯并呋喃的芳烃受体亲和性(pEC50)以及芳香和杂环芳香胺的诱导有机体变异力(lnR)进行了计算预测.结果表明,基于扩展距离矩阵范数指数建立的构效关系模型可以很好地预测pEC50和lnR.其中, pEC50预测结果的平均绝对误差(AAD)为0.403,相关性系数r2=0.876, lnR预测结果的AAD为0.702, r2=0.779.与其他预测方法的对比结果表明,本工作不仅能够利用一个完全相同的数学表达模型同时对pEC50和lnR进行预测,而且预测结果在准确性和稳定性上都有显著改善.

  16. Structure-activity relationship of nerve-highlighting fluorophores.

    Directory of Open Access Journals (Sweden)

    Summer L Gibbs

    Full Text Available Nerve damage is a major morbidity associated with numerous surgical interventions. Yet, nerve visualization continues to challenge even the most experienced surgeons. A nerve-specific fluorescent contrast agent, especially one with near-infrared (NIR absorption and emission, would be of immediate benefit to patients and surgeons. Currently, there are only three classes of small molecule organic fluorophores that penetrate the blood nerve barrier and bind to nerve tissue when administered systemically. Of these three classes, the distyrylbenzenes (DSBs are particularly attractive for further study. Although not presently in the NIR range, DSB fluorophores highlight all nerve tissue in mice, rats, and pigs after intravenous administration. The purpose of the current study was to define the pharmacophore responsible for nerve-specific uptake and retention, which would enable future molecules to be optimized for NIR optical properties. Structural analogs of the DSB class of small molecules were synthesized using combinatorial solid phase synthesis and commercially available building blocks, which yielded more than 200 unique DSB fluorophores. The nerve-specific properties of all DSB analogs were quantified using an ex vivo nerve-specific fluorescence assay on pig and human sciatic nerve. Results were used to perform quantitative structure-activity relationship (QSAR modeling and to define the nerve-specific pharmacophore. All DSB analogs with positive ex vivo fluorescence were tested for in vivo nerve specificity in mice to assess the effect of biodistribution and clearance on nerve fluorescence signal. Two new DSB fluorophores with the highest nerve to muscle ratio were tested in pigs to confirm scalability.

  17. Structural Join and Staircase Join Algorithms of Sibling Relationship

    Institute of Scientific and Technical Information of China (English)

    Chang-Xuan Wan; Xi-Ping Liu

    2007-01-01

    The processing of XML queries can result in evaluation of various structural relationships. Efficient algorithms for evaluating ancestor-descendant and parent-child relationships have been proposed. Whereas the problems of evaluating preceding-sibling-following-sibling and preceding-following relationships are still open. In this paper, we studied the struc-tural join and staircase join for sibling relationship. First, the idea of how to filter out and minimize unnecessary reads of elements using parent's structural information is introduced, which can be used to accelerate structural joins of parent-child and preceding-sibling-following-sibling relationships. Second, two efficient structural join algorithms of sibling relationship are proposed. These algorithms lead to optimal join performance: nodes that do not participate in the join can be judged beforehand and then skipped using B+-tree index. Besides, each element list joined is scanned sequentially once at most.Furthermore, output of join results is sorted in document order. We also discussed the staircase join algorithm for sibling axes. Studies show that, staircase join for sibling axes is close to the structural join for sibling axes and shares the samecharacteristic of high efficiency. Our experimental results not only demonstrate the effectiveness of our optimizing techniquesfor sibling axes, but also validate the efficiency of our algorithms. As far as we know, this is the first work addressing thisproblem specially.

  18. Symplecticity and relationships among the fundamental properties in linear optics

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2010-12-01

    Full Text Available Because of symplecticity the four   fundamental first-order optical properties of an optical system are not independent.  Relationships among them reduce the number of degrees of freedom of a system’s   transference from 16 to 10.  There are many such relationships, they are not easy to remember, they take many forms and they are often needed in derivations.  The purpose of this paper is to provide in one place a comprehensive collection of those that have proved useful in linear optics generally and in the context of the eye particularly.  The paper also offers aids to memorizing some of the results, derives most of them and along the way introducesthe basic notions underlying symplecticity.  The relationship to another important class of matrices, the Hamiltonian matrices, is discussed together with their potential role in statistical analysis of the eye.  Augmented symplectic matrices are also defined and their relationship to augmented Hamiltonian matrices described.  An appendix gives numerical examples of symplectic and Hamiltonian matrices and shows how they may be recognized and constructed.  (S Afr Optom 2010 69(1 3-13

  19. The Relationship Communication Structure - Uncertainty Avoidance

    Directory of Open Access Journals (Sweden)

    Doru Alexandru Pleşea

    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

  20. 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…

  1. Electronic Properties in a Hierarchical Multilayer Structure

    Institute of Scientific and Technical Information of China (English)

    ZHU Chen-Ping; XIONG Shi-Jie

    2001-01-01

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

  2. Preliminary Research on Relationship Between Dielectric Property and Microstructure of Rabbit Liver

    Institute of Scientific and Technical Information of China (English)

    ZHU Jian-bo; SHI Xue-tao; YOU Fu-sheng; WANG Hang; WANG Hui; CAI Zhan-xiu; DONG Xiu-zhen

    2014-01-01

    The dielectric properties in vitro present characteristic changes along with the alteration of metabolic activities, which can be detected from tissue micro-structure. The dielectric properties of tissues are closely related to its viability, but the relationship remains unclear to us. This study aims to specify the relationship between dielectric parameters and microstructure of living tissues and to try to explain the influence of tissue viability on dielectric properties. Nine rabbits were studied in this experiment. The impedance spectroscopy (10 Hz-1 MHz) and microstructure were determined at different time intervals (from 5 min to 7 h) after samples were prepared. Some characteristic parameters were extracted to analyze the relationship between them. The inactivation process characterized by the microstructurs could be detected by means of dielectric parameters:the microstructures had no obvious change within 30 min and cell swelling caused by osmosis led to the decrease of extracellular ion concentration, resulting in the rise of lowfrequency imped ance after 30 min. The reduction of impedance was accompanied by the expanding intercellular area and irregular cell shape caused by the gradual destruction of cell membrane.The functions between alteration rate of intercellular area and Cole-Cole model parameters were also established. There is a strong correlative relationship between dielectric properties and microstructure. The dielectric spectrum can be a rapid and innocuous method to monitor the status of tissues. In the future, it may be of great help for clinical application, especially in transplantation.

  3. Relationships between physical properties and sequence in silkworm silks

    Science.gov (United States)

    Malay, Ali D.; Sato, Ryota; Yazawa, Kenjiro; Watanabe, Hiroe; Ifuku, Nao; Masunaga, Hiroyasu; Hikima, Takaaki; Guan, Juan; Mandal, Biman B.; Damrongsakkul, Siriporn; Numata, Keiji

    2016-06-01

    Silk has attracted widespread attention due to its superlative material properties and promising applications. However, the determinants behind the variations in material properties among different types of silk are not well understood. We analysed the physical properties of silk samples from a variety of silkmoth cocoons, including domesticated Bombyx mori varieties and several species from Saturniidae. Tensile deformation tests, thermal analyses, and investigations on crystalline structure and orientation of the fibres were performed. The results showed that saturniid silks produce more highly-defined structural transitions compared to B. mori, as seen in the yielding and strain hardening events during tensile deformation and in the changes observed during thermal analyses. These observations were analysed in terms of the constituent fibroin sequences, which in B. mori are predicted to produce heterogeneous structures, whereas the strictly modular repeats of the saturniid sequences are hypothesized to produce structures that respond in a concerted manner. Within saturniid fibroins, thermal stability was found to correlate with the abundance of poly-alanine residues, whereas differences in fibre extensibility can be related to varying ratios of GGX motifs versus bulky hydrophobic residues in the amorphous phase.

  4. Structure- and dose-absorption relationships of coffee polyphenols.

    Science.gov (United States)

    Erk, Thomas; Hauser, Johanna; Williamson, Gary; Renouf, Mathieu; Steiling, Heike; Dionisi, Fabiola; Richling, Elke

    2014-01-01

    Chlorogenic acids (CGAs) from coffee have biological effects related to human health. Thus, specific data on their bioavailability in the upper gastrointestinal tract are of high interest, since some molecules are absorbed here and so are not metabolized by colonic microflora. Up to now, no data on structure-absorption relationships for CGAs have been published, despite this being the most consumed group of polyphenols in the western diet. To address this gap, we performed ex vivo absorption experiments with pig jejunal mucosa using the Ussing chamber model (a model simulating the mucosa and its luminal/apical side). The main coffee polyphenols, caffeoylquinic acid (CQA), feruloylquinic acid (FQA), caffeic acid (CA), dicaffeoylquinic acid (diCQA), and D-(-)-quinic acid (QA), were incubated in individual experiments equivalent to gut lumen physiologically achievable concentrations (0.2-3.5 mM). Identification and quantification were performed with HPLC-diode array detection and HPLC-MS/MS. Additionally, the presence of ABC-efflux transporters was determined by Western blot analysis. The percentages of initially applied CGAs that were absorbed through the jejunal pig mucosa were, in increasing order: diCQA, trace; CQA, ≈ 1%; CA, ≈ 1.5%; FQA, ≈ 2%; and QA, ≈ 4%. No differences were observed within the CGA subgroups. Dose-absorption experiments with 5-CQA suggested a passive diffusion (nonsaturable absorption and a linear dose-flux relationship) and its secretion was affected by NaN3 , indicating an active efflux. The ABC-efflux transporters MDR 1 and MRP 2 were identified in pig jejunal mucosa for the first time. We conclude that active efflux plays a significant role in CGA bioavailability and, further, that the mechanism of CGA absorption in the jejunum is governed by their physicochemical properties.

  5. 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.

  6. Property segment and REIT capital structure

    NARCIS (Netherlands)

    Ertugrul, M.; Giambona, E.

    2011-01-01

    This paper relies on an increasing number of industry equilibrium studies linking a firm to its industry peers to help explain the observed REIT capital structure variation within property segments beyond what is possible with the traditional partial equilibrium trade-off and pecking order theories,

  7. Property segment and REIT capital structure

    NARCIS (Netherlands)

    Ertugrul, M.; Giambona, E.

    2008-01-01

    This paper relies on an increasing number of industry equilibrium studies linking a firm to its industry peers to help ; explain the observed REIT capital structure variation within property segments beyond what is possible with the ; traditional partial equilibrium trade-off and pecking order theor

  8. Structural properties of prokaryotic promoter regions correlate with functional features.

    Directory of Open Access Journals (Sweden)

    Pieter Meysman

    Full Text Available The structural properties of the DNA molecule are known to play a critical role in transcription. In this paper, the structural profiles of promoter regions were studied within the context of their diversity and their function for eleven prokaryotic species; Escherichia coli, Klebsiella pneumoniae, Salmonella Typhimurium, Pseudomonas auroginosa, Geobacter sulfurreducens Helicobacter pylori, Chlamydophila pneumoniae, Synechocystis sp., Synechoccocus elongates, Bacillus anthracis, and the archaea Sulfolobus solfataricus. The main anchor point for these promoter regions were transcription start sites identified through high-throughput experiments or collected within large curated databases. Prokaryotic promoter regions were found to be less stable and less flexible than the genomic mean across all studied species. However, direct comparison between species revealed differences in their structural profiles that can not solely be explained by the difference in genomic GC content. In addition, comparison with functional data revealed that there are patterns in the promoter structural profiles that can be linked to specific functional loci, such as sigma factor regulation or transcription factor binding. Interestingly, a novel structural element clearly visible near the transcription start site was found in genes associated with essential cellular functions and growth in several species. Our analyses reveals the great diversity in promoter structural profiles both between and within prokaryotic species. We observed relationships between structural diversity and functional features that are interesting prospects for further research to yet uncharacterized functional loci defined by DNA structural properties.

  9. 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.

  10. 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...... inertia. These are important insights, because they suggest that with the right design, organizations may be both more flexible and reliable than commonly believed....

  11. Structure–mechanics property relationship of waste derived biochars

    Energy Technology Data Exchange (ETDEWEB)

    Das, Oisik, E-mail: odas566@aucklanduni.ac.nz [Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142 (New Zealand); Sarmah, Ajit K., E-mail: a.sarmah@auckland.ac.nz [Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142 (New Zealand); Bhattacharyya, Debes, E-mail: d.bhattacharyya@auckland.ac.nz [Department of Mechanical Engineering, Center for Advanced Composite Materials, University of Auckland, Auckland 1142 (New Zealand)

    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 60 min residence time was found to have the highest hardness and elastic modulus of 4.29 and 25.01 GPa, respectively. It was shown that a combination of higher heat treatment (≥ 500 °C) temperature and longer residence time (~ 60 min) 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. - Highlights: • Characterization was done on waste based biochars which included nanoindentation. • Pine saw dust biochar made at 900 °C for 60 min had highest hardness/modulus. • Combination of temperature/residence time affect biochar's mechanical propertie.s • Aromaticity and crystallinity positively affected biochar's mechanical properties.

  12. Structural and Magnetic Properties of Trigonal Iron

    CERN Document Server

    Fox, S

    1995-01-01

    First principles calculations of the electronic structure of trigonal iron were performed using density function theory. The results are used to predict lattice spacings, magnetic moments and elastic properties; these are in good agreement with experiment for both the bcc and fcc structures. We find however, that in extracting these quantities great care must be taken in interpreting numerical fits to the calculated total energies. In addition, the results for bulk iron give insight into the properties of thin iron films. Thin films grown on substrates with mismatched lattice constants often have non-cubic symmetry. If they are thicker than a few monolayers their electronic structure is similar to a bulk material with an appropriately distorted geometry, as in our trigonal calculations. We recast our bulk results in terms of an iron film grown on the (111) surface of an fcc substrate, and find the predicted strain energies and moments accurately reflect the trends for iron growth on a variety of substrates.

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

    Science.gov (United States)

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

    2014-05-01

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

  14. 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.

  15. Structure-property relationships of novel microwave dielectric ceramics with low sintering temperatures: (Na(0.5x)Bi(0.5x)Ca(1-x))MoO(4).

    Science.gov (United States)

    Guo, Jing; Zhou, Di; Li, Yong; Shao, Tao; Qi, Ze-Ming; Jin, Biao-Bing; Wang, Hong

    2014-08-21

    A novel series of microwave dielectric ceramics (Na0.5xBi0.5xCa1-x)MoO4 (0 ≤ x ≤ 0.6) was synthesized by the solid state reaction method. The crystal structures, microstructures, dielectric responses, and vibrational properties were investigated using X-ray diffraction, scanning electron microscopy, a microwave network analyzer, and terahertz, Raman and infrared spectroscopies. All the samples could be sintered well below 850 °C and a scheelite solid solution could be formed without any secondary phase. At x = 0.5 and x = 0.6, low-firing (750-775 °C) high performance microwave dielectric materials were obtained with permittivities of 19.1-21.9, Q × f values of 20 660-22 700 GHz, and near-zero temperature coefficients. The factors affecting microwave dielectric properties were discussed based on the vibrational data. As revealed by Raman spectroscopy, the disorder degree grows with x rising, which might increase the permittivities and decrease the Q × f values. The infrared spectra were analyzed using the classical harmonic oscillator model, and the complex dielectric responses gained from the fits were extrapolated down to the microwave and THz range. It is believed that the external vibration modes located at low frequencies dominate the main dielectric polarization contributions, especially the Na-O/Bi-O translational mode. This result indicates that the microwave dielectric properties of (Na0.5xBi0.5xCa1-x)MoO4 ceramics mainly depend on the behavior of AO8 polyhedra.

  16. Relationship between physical properties and sensory attributes of carbonated beverages.

    Science.gov (United States)

    Kappes, S M; Schmidt, S J; Lee, S-Y

    2007-01-01

    Bulk sweeteners provide functional properties in beverages, including sweet taste, bulking, bitter masking, structure, and mouthfeel. Diet beverages come closer to the taste of regular beverages using a blend of high-intensity sweeteners; however, some properties, including bulking, structure, and mouthfeel, remain significantly different. Relating physical properties to sensory characteristics is an important step in understanding why mouthfeel differences are apparent in beverages sweetened with alternative sweeteners compared to bulk sweeteners. The objectives of this research were to (1) measure sweetener profile, Brix, refractive index, viscosity, a(w), carbonation, titratable acidity, and pH of commercial carbonated beverages; and (2) correlate the physical property measurements to descriptive analysis of the beverages. Correlation analysis, partial least squares, canonical correlation analysis, and cluster analysis were used to analyze the data. Brix, viscosity, and sweet taste were highly correlated among one another and were all negatively correlated to a(w). Carbonated and decarbonated pH were highly correlated to each other and were both negatively correlated to mouthcoating. Numbing, burn, bite, and carbonation were highly correlated to total acidity, citric acid, and ascorbic acid and negatively correlated to phosphoric acid. The mouthfeel difference between diet and regular lemon/lime carbonated beverages is small and may be related to overall differences between flavor, acid, and sweetener types and usage levels. This research is significant because it demonstrates the use of both sensory attributes and physical properties to identify types of ingredients and levels that may decrease the mouthfeel perception differences between regular and diet carbonated beverages, which could consequently lead to higher acceptance of diet beverages by the consumers of regular.

  17. Structure and Magnetic Properties of Lanthanide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, James Henry [Vanderbilt Univ., Nashville, TN (United States)

    2014-06-01

    We have had considerable success on this project, particularly in the understanding of the relationship between nanostructure and magnetic properties in lanthanide nanocrystals. We also have successfully facilitated the doctoral degrees of Dr. Suseela Somarajan, in the Department of Physics and Astronomy, and Dr. Melissa Harrison, in the Materials Science Program. The following passages summarize the various accomplishments that were featured in 9 publications that were generated based on support from this grant. We thank the Department of Energy for their generous support of our research efforts in this area of materials science, magnetism, and electron microscopy.

  18. Structural properties of small rhodium clusters

    Science.gov (United States)

    Soon, Yee Yeen; Lim, Thong Leng; Yoon, Tiem Leong

    2015-04-01

    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.

  19. 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.

  20. Flavonoids promoting HaCaT migration: I. Hologram quantitative structure-activity relationships.

    Science.gov (United States)

    Cho, Moonjae; Yoon, Hyuk; Park, Mijoo; Kim, Young Hwa; Lim, Yoongho

    2014-03-15

    Cell migration plays an important role in multicellular development and preservation. Because wound healing requires cell migration, compounds promoting cell migration can be used for wound repair therapy. Several plant-derived polyphenols are known to promote cell migration, which improves wound healing. Previous studies of flavonoids on cell lines have focused on their inhibitory effects and not on wound healing. In addition, studies of flavonoids on wound healing have been performed using mixtures. In this study, individual flavonoids were used for cellular migration measurements. Relationships between the cell migration effects of flavonoids and their structural properties have never been reported. Here, we investigated the migration of keratinocytes caused by 100 flavonoids and examined their relationships using hologram quantitative structure-activity relationships. The structural conditions responsible for efficient cell migration on keratinocyte cell lines determined from the current study will facilitate the design of flavonoids with improved activity.

  1. Polarization properties of localized structures in VCSELs

    Science.gov (United States)

    Averlant, Etienne; Tlidi, Mustapha; Ackemann, Thorsten; Thienpont, Hugo; Panajotov, Krassimir

    2016-04-01

    Broad area Vertical-Cavity Surface-Emitting Lasers (VCSELs) have peculiar polarization properties which are a field of study by itself.1-3 These properties have already been used for localized structure generation, in a simple configuration, where only one polarization component was used.4 Here, we present new experimental and theoretical results on the complex polarization behavior of localized structures generated in an optically-injected broad area VCSEL. A linear stability analysis of the spin-flip VCSEL model is performed for the case of broad area devices, in a restrained and experimentally relevant parameter set. Numerical simulations are performed, in one and two dimensions. They reveal existence of vector localized structures. These structures have a complex polarization state, which is not simply a linear polarization following the one of the optical injection. Experimental results confirm theoretical predictions. Applications of this work can lead to the encoding of small color images in the polarization state of an ensemble of localized structures at the surface of a broad area VCSEL.

  2. Acoustical properties of nonwoven fiber network structures

    Science.gov (United States)

    Tascan, Mevlut

    Sound insulation is one of the most important issues for the automotive and building industries. Because they are porous fibrous structures, textile materials can be used as sound insulating and sound absorbing materials. Very high-density materials such as steel can insulate sound very effectively but these rigid materials reflect most of the sound back to the environment, causing sound pollution. Additionally, because high-density, rigid materials are also heavy and high cost, they cannot be used for sound insulation for the automotive and building industries. Nonwoven materials are more suitable for these industries, and they can also absorb sound in order to decrease sound pollution in the environment. Therefore, nonwoven materials are one of the most important materials for sound insulation and absorption applications materials. Insulation and absorption properties of nonwoven fabrics depend on fiber geometry and fiber arrangement within the fabric structure. Because of their complex structure, it is very difficult to define the microstructure of nonwovens. The structure of nonwovens only has fibers and voids that are filled by air. Because of the complexity of fiber-void geometry, there is still not a very accurate theory or model that defines the structural arrangement. A considerable amount of modeling has been reported in literature [1--19], but most models are not accurate due to the assumptions made. Voids that are covered by fibers are called pores in nonwoven structures and their geometry is very important, especially for the absorption properties of nonwovens. In order to define the sound absorption properties of nonwoven fabrics, individual pore structure and the number of pores per unit thickness of the fabric should be determined. In this research, instead of trying to define pores, the properties of the fibers are investigated and the number of fibers per volume of fabric is taken as a parameter in the theory. Then the effect of the nonwoven

  3. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    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.

  4. RaptorX-Property: a web server for protein structure property prediction.

    Science.gov (United States)

    Wang, Sheng; Li, Wei; Liu, Shiwang; Xu, Jinbo

    2016-07-08

    RaptorX Property (http://raptorx2.uchicago.edu/StructurePropertyPred/predict/) is a web server predicting structure property of a protein sequence without using any templates. It outperforms other servers, especially for proteins without close homologs in PDB or with very sparse sequence profile (i.e. carries little evolutionary information). This server employs a powerful in-house deep learning model DeepCNF (Deep Convolutional Neural Fields) to predict secondary structure (SS), solvent accessibility (ACC) and disorder regions (DISO). DeepCNF not only models complex sequence-structure relationship by a deep hierarchical architecture, but also interdependency between adjacent property labels. Our experimental results show that, tested on CASP10, CASP11 and the other benchmarks, this server can obtain ∼84% Q3 accuracy for 3-state SS, ∼72% Q8 accuracy for 8-state SS, ∼66% Q3 accuracy for 3-state solvent accessibility, and ∼0.89 area under the ROC curve (AUC) for disorder prediction.

  5. 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…

  6. Antiproliferative and Structure Activity Relationships of Amaryllidaceae Alkaloids.

    Science.gov (United States)

    Cedrón, Juan C; Ravelo, Ángel G; León, Leticia G; Padrón, José M; Estévez-Braun, Ana

    2015-07-30

    The antiproliferative activity of a set of seven natural Amaryllidaceae alkaloids and 32 derivatives against four cancer cell lines (A2780, SW1573, T47-D and WiDr) was determined. The best antiproliferative activities were achieved with alkaloids derived from pancracine (2), haemanthamine (6) and haemantidine (7). For each skeleton, some structure-activity relationships were outlined.

  7. Structure activity relationship of selective GABA uptake inhibitors

    DEFF Research Database (Denmark)

    Vogensen, Stine Byskov; Jørgensen, Lars; Madsen, Karsten K;

    2015-01-01

    A series of β-amino acids with lipophilic diaromatic side chain was synthesized and characterized pharmacologically on mouse γ-amino butyric acid (GABA) transporter subtypes mGAT1-4 in order to investigate structure activity relationships (SAR) for mGAT2 (corresponding to hBGT-1). Variation...

  8. Structural and dynamical properties of complex networks

    Science.gov (United States)

    Ghoshal, Gourab

    Recent years have witnessed a substantial amount of interest within the physics community in the properties of networks. Techniques from statistical physics coupled with the widespread availability of computing resources have facilitated studies ranging from large scale empirical analysis of the worldwide web, social networks, biological systems, to the development of theoretical models and tools to explore the various properties of these systems. Following these developments, in this dissertation, we present and solve for a diverse set of new problems, investigating the structural and dynamical properties of both model and real world networks. We start by defining a new metric to measure the stability of network structure to disruptions, and then using a combination of theory and simulation study its properties in detail on artificially generated networks; we then compare our results to a selection of networks from the real world and find good agreement in most cases. In the following chapter, we propose a mathematical model that mimics the structure of popular file-sharing websites such as Flickr and CiteULike and demonstrate that many of its properties can solved exactly in the limit of large network size. The remaining part of the dissertation primarily focuses on the dynamical properties of networks. We first formulate a model of a network that evolves under the addition and deletion of vertices and edges, and solve for the equilibrium degree distribution for a variety of cases of interest. We then consider networks whose structure can be manipulated by adjusting the rules by which vertices enter and leave the network. We focus in particular on degree distributions and show that, with some mild constraints, it is possible by a suitable choice of rules to arrange for the network to have any degree distribution we desire. In addition we define a simple local algorithm by which appropriate rules can be implemented in practice. Finally, we conclude our

  9. 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 η 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.

  10. Structural and magnetotransport properties of discontinuous Co/SiO{sub 2} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Denardin, J.C. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas S.P. (Brazil)]. E-mail: denardin@ifi.unicamp.br; Knobel, M. [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas S.P. (Brazil); Dorneles, L.S. [Department de Fisica, CCNE, UFSM, 97105-900, Santa Maria, R.S. (Brazil); Schelp, L.F. [Department de Fisica, CCNE, UFSM, 97105-900, Santa Maria, R.S. (Brazil)

    2004-09-25

    Results of structural, magnetic and transport properties of magnetic Co/SiO{sub 2} granular multilayers, consisting of successive planes of nanosized cobalt clusters embedded in SiO{sub 2} and produced by sequential deposition, are presented. Microscopy shows that samples can be composed of a periodical array of Co nanoparticles. Relationships between the nanostructure and magnetotransport properties are discussed.

  11. 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.

  12. The textual idea and its relationship to discourse structure

    Directory of Open Access Journals (Sweden)

    Cosmin Dănut BOCĂNIALĂ

    2000-12-01

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

  13. Relationship between Structures and Carcinogenicities of Heterocyclic Amines

    Institute of Scientific and Technical Information of China (English)

    JU Xue-hai; DAI Qian-huan; CHEN Sha; WANG Wen-jun

    2004-01-01

    Semi-empirical molecular orbital calculations were performed on heterocyclic aromatic amines(HCAs). The relationship between the structures and the carcinogenicities can be rationally elucidated by the models based on the metabolism of HCAs and the Di-region theory. The degree of easiness for the formation of Di-region electrophilic centers determines the carcinogenic activity. There is a good linear relationship between the observed carcinogenicities and the PM3 calculated parameters, with r=0.973 and F=29.8>(F*0.*01).

  14. Characterization of ion-exchange membrane materials: properties vs structure.

    Science.gov (United States)

    Berezina, N P; Kononenko, N A; Dyomina, O A; Gnusin, N P

    2008-06-22

    This review focuses on the preparation, structure and applications of ion-exchange membranes formed from various materials and exhibiting various functions (electrodialytic, perfluorinated sulphocation-exchange and novel laboratory-tested membranes). A number of experimental techniques for measuring electrotransport properties as well as the general procedure for membrane testing are also described. The review emphasizes the relationships between membrane structures, physical and chemical properties and mechanisms of electrochemical processes that occur in charged membrane materials. The water content in membranes is considered to be a key factor in the ion and water transfer and in polarization processes in electromembrane systems. We suggest the theoretical approach, which makes it possible to model and characterize the electrochemical properties of heterogeneous membranes using several transport-structural parameters. These parameters are extracted from the experimental dependences of specific electroconductivity and diffusion permeability on concentration. The review covers the most significant experimental and theoretical research on ion-exchange membranes that have been carried out in the Membrane Materials Laboratory of the Kuban State University. These results have been discussed at the conferences "Membrane Electrochemistry", Krasnodar, Russia for many years and were published mainly in Russian scientific sources.

  15. Table of periodic properties of fullerenes based on structural parameters.

    Science.gov (United States)

    Torrens, Francisco

    2004-01-01

    The periodic table (PT) of the elements suggests that hydrogen could be the origin of everything else. The construction principle is an evolutionary process that is formally similar to those of Darwin and Oparin. The Kekulé structure count and permanence of the adjacency matrix of fullerenes are related to structural parameters involving the presence of contiguous pentagons p, q and r. Let p be the number of edges common to two pentagons, q the number of vertices common to three pentagons, and r the number of pairs of nonadjacent pentagon edges shared between two other pentagons. Principal component analysis (PCA) of the structural parameters and cluster analysis (CA) of the fullerenes permit classifying them and agree. A PT of the fullerenes is built based on the structural parameters, PCA and CA. The periodic law does not have the rank of the laws of physics. (1) The properties of the fullerenes are not repeated; only, and perhaps, their chemical character. (2) The order relationships are repeated, although with exceptions. The proposed statement is the following: The relationships that any fullerene p has with its neighbor p + 1 are approximately repeated for each period.

  16. Nitrogenase structure and function relationships by density functional theory.

    Science.gov (United States)

    Harris, Travis V; Szilagyi, Robert K

    2011-01-01

    Modern density functional theory has tremendous potential with matching popularity in metalloenzymology to reveal the unseen atomic and molecular details of structural data, spectroscopic measurements, and biochemical experiments by providing insights into unobservable structures and states, while also offering theoretical justifications for observed trends and differences. An often untapped potential of this theoretical approach is to bring together diverse experimental structural and reactivity information and allow for these to be critically evaluated at the same level. This is particularly applicable for the tantalizingly complex problem of the structure and molecular mechanism of biological nitrogen fixation. In this chapter we provide a review with extensive practical details of the compilation and evaluation of experimental data for an unbiased and systematic density functional theory analysis that can lead to remarkable new insights about the structure-function relationships of the iron-sulfur clusters of nitrogenase.

  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. Composite Polymer Electrolytes: Nanoparticles Affect Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2016-11-01

    Full Text Available Composite polymer electrolytes (CPEs can significantly improve the performance in electrochemical devices such as lithium-ion batteries. This review summarizes property/performance relationships in the case where nanoparticles are introduced to polymer electrolytes. It is the aim of this review to provide a knowledge network that elucidates the role of nano-additives in the CPEs. Central to the discussion is the impact on the CPE performance of properties such as crystalline/amorphous structure, dielectric behavior, and interactions within the CPE. The amorphous domains of semi-crystalline polymer facilitate the ion transport, while an enhanced mobility of polymer chains contributes to high ionic conductivity. Dielectric properties reflect the relaxation behavior of polymer chains as an important factor in ion conduction. Further, the dielectric constant (ε determines the capability of the polymer to dissolve salt. The atom/ion/nanoparticle interactions within CPEs suggest ways to enhance the CPE conductivity by generating more free lithium ions. Certain properties can be improved simultaneously by nanoparticle addition in order to optimize the overall performance of the electrolyte. The effects of nano-additives on thermal and mechanical properties of CPEs are also presented in order to evaluate the electrolyte competence for lithium-ion battery applications.

  19. Relationship Between Solar Wind Speed and Coronal Magnetic Field Properties

    CERN Document Server

    Fujiki, Ken'ichi; Iju, Tomoya; Hakamada, Kazuyuki; Kojima, Masayoshi

    2015-01-01

    We have studied the relationship between the solar-wind speed $[V]$ and the coronal magnetic-field properties (a flux expansion factor [$f$] and photospheric magnetic-field strength [$B_{\\mathrm{S}}$]) at all latitudes using data of interplanetary scintillation and solar magnetic field obtained for 24 years from 1986 to 2009. Using a cross-correlation analyses, we verified that $V$ is inversely proportional to $f$ and found that $V$ tends to increase with $B_{\\mathrm{S}}$ if $f$ is the same. As a consequence, we find that $V$ has extremely good linear correlation with $B_{\\mathrm{S}}/f$. However, this linear relation of $V$ and $B_{\\mathrm{S}}/f$ cannot be used for predicting the solar-wind velocity without information on the solar-wind mass flux. We discuss why the inverse relation between $V$ and $f$ has been successfully used for solar-wind velocity prediction, even though it does not explicitly include the mass flux and magnetic-field strength, which are important physical parameters for solar-wind accele...

  20. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay (< 2 m) could increase water-soluble Hg (r = 0.700*). Soil organic matter (OM) could enhance the increase of elemental Hg (r = 0.674*). The higher the base saturation percentage (BSP), the more the residual Hg (r = 0.684*). Organic Hg, the sum of acid-soluble organic Hg. and alkali-soluble Hg, was positively affected by silt (2~20μm) but negatively affected by pH, with the direct path coefficients amounting to 1.0487 and 0.5121, respectively. The positive effect of OM and negative effect of BSP on organic Hg were the most significant, with the direct path coefficients being 0.7614 and -0.8527, respectively. The indirect effect of clay (< 2 μm) via BSP (path coefficient = 0.4186) was the highest, showing that the real influencing factor in the effect of clay (< 2 μm) on acid-soluble organic Hg was BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content, and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  1. Structure and Property of Bamboo Fiber

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The chemical composition, fiber characteristics, crystalline structure, mechanical properties and thermal behavior of the five species of bamboo (Phyllostachys edulis cv.Pachyloe, Bambusa tootisk, Arundinaia amabilis, B.vulgaris cv. Vittata, and Dendrocalamus affinis) were studied with IR, X-ray, DSC and chemical analyses. The results indicated that the benzene-ethanol extractive content of bamboo was higher than that of wood, the content of lignin and the content of pentosan were 19.1% - 25.3% and 14.9% - ...

  2. Molecular and structural analysis of viscoelastic properties

    Science.gov (United States)

    Yapp, Rebecca D.; Kalyanam, Sureshkumar; Insana, Michael F.

    2007-03-01

    Elasticity imaging is emerging as an important tool for breast cancer detection and monitoring of treatment. Viscoelastic image contrast in breast lesions is generated by disease specific processes that modify the molecular structure of connective tissues. We showed previously that gelatin hydrogels exhibit mechanical behavior similar to native collagen found in breast tissue and therefore are suitable as phantoms for elasticity imaging. This paper summarizes our study of the viscoelastic properties of hydrogels designed to discover molecular-scale sources of elasticity image contrast.

  3. Quantitative Structure-Property Relationship for Polychlorinated Biphenyls: Toxicity and Structure by Density Functional Theory%基于密度泛函理论计算的多氯联苯毒性的定量结构-性质关系研究

    Institute of Scientific and Technical Information of China (English)

    龙杰义; 易海波; 刘星楷; 汪易非

    2012-01-01

    Polychlorinated biphenyls(PCBs) with hydrophobicity,lipophilicity and high toxicity,are a group of synthetic persistent organic contaminants,and have caused people widespread concern.In this work,density functional theory(DFT) was employed to calculate some structural parameters of PCBs,such as the negative charge density of the benzene ring(Q),ELUMO,electrophilicity index(ω),and the relationship of toxicity of PCBs with coplanarity,the number of substituted chlorines(NCl),Q,and ω was also investigated.Using SPSS17 program,the relevancy of these structural parameters with n-octanol-water partition coefficients(KOW) was analyzed,and multiple linear regression equations of lg KOW for PCBs were constructed.Tests of these quantitative structure-property relationship(QSPR) equations were performed to ensure the stability using cross-validation method,and those equations were also used to predict the toxicity of PCBs.The established QSPR equation based on NCl and ω is simple and reliable,and the predicted lg KOWvalues of PCBs agree well with experimental results.%多氯联苯(PCBs)是一类人工合成的难降解有机物,疏水亲油、毒性大,引起了人们普遍关注.通过密度泛函理论(DFT)计算获得PCBs苯环上的负电荷密度(Q)、最低空轨道能量(ELUMO)、亲电指数(ω)等结构参数,并分析了PCBs毒性与其苯环间的共平面性、氯原子取代数(NCl)、Q以及ω等结构参数之间的关系.采用SPSS17统计软件分析了上述结构参数与PCBs毒性表征量正辛醇-水分配系数(KOW)的关联度,并构建lg KOW的多元线性回归方程.采用"交叉检验"方法检验所构建的lg KOW定量结构-性质关系(QSPR)方程的稳定性,并用于预测PCBs的毒性.由NCl和ω构造出的QSPR方程简单实用、可靠,PCBs的lg KOW计算值与实验结果吻合良好.

  4. Structure - property relations of high-temperature composite polymer matrices

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, R.J.; Jurek, R.J.; Larive, D.E. [Michigan Molecular Institute, Midland, MI (United States); Tung, C.M. [Northrop Corp., Hawthorne, CA (United States); Donnellan, T. [Naval Air Development Center, Warminster, PA (United States)

    1993-12-31

    The structure-deformation-failure mode-mechanical property relations of high-temperature thermoplastic polyimide and thermoset bismaleimide (BMI) polymeric matrices and their composites will be discussed. In the case of polyimides, the effects of test temperature, thermal history, strain rate, type of filler, and filler volume fraction on structure - property relations will be discussed. For BMIs we report systematic Fourier transform infrared spectroscopy and differential scanning calorimetry studies of the cure reactions as a function of chemical composition and time - temperature cure conditions and then describe the resultant cross-linked network structure based on our understanding of the cure reactions. The optimization of the BMI matrix toughness will be considered in terms of network structure and process-induced matrix microcracking. We also describe optimization of composite prepreg, lamination and postcure conditions based on cure kinetics, and their relationship to the BMI viscosity-time-temperature profiles. The critical processing-performance limitations of high-temperature polymer matrices will be critically discussed, and toughening approaches to address these limitations, such as toughness over a wide temperature range, will be presented. 7 refs., 2 figs., 1 tab.

  5. Structure and properties of copper after large strain deformation

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, Kinga; Molak, Rafal M.; Pakiela, Zbigniew

    2010-05-15

    Structure and properties of Cu in dependence on strain (from {epsilon}{proportional_to} 0.9 to {epsilon}{proportional_to} 15) during multi-axial compression processing at room temperature was investigated. The evolution of dislocation structure, misorientation distribution and crystallite size were observed by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The mechanical properties of yield strength (YS), ultimate tensile strength (UTS) and uniform elongation was performed on MTS QTest/10 machine equipped with digital image correlation method (DIC). The structure-flow stress relationship of multi-axial compression processing material at strains {epsilon}{proportional_to} 3.5 and {epsilon}{proportional_to} 5.5 is discussed. It is found that processing does not produce any drastic changes in deformation structure and the microstructural refinement is slow. These results indicate that dynamic recrystallization plays an important role during multi-axial compression process in this range of deformation (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Function-structure relationships of acetylated pea starches

    NARCIS (Netherlands)

    Huang, J.

    2006-01-01

    Cowpea, chickpea and yellow pea starches were studied and the results showed that their properties were strongly related to the chemical fine structures of the starches. Furthermore, granular starches were modified using two types of chemical acetylation reagents and then separated into different si

  7. Toward the recognition of structure-function relationships in galactomannans.

    NARCIS (Netherlands)

    Daas, P.; Grolle, K.; Vliet, van T.; Schols, H.A.; Jongh, de H.H.J.

    2002-01-01

    In this paper the determination of the physical/rheological characteristics is described for a series of commercial galactomannans of which the structural details have been reported previously. Both solubility of the galactomannans and rheological properties of galactomannan solutions and galactoman

  8. 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.

  9. STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

    Institute of Scientific and Technical Information of China (English)

    Xian-feng Li; Chang-fa Xiao

    2005-01-01

    Composite polyurethane (PU)-SiO2 hollow fiber membranes were successfully prepared via optimizing the technique of dry-jet wet spinning, and their pressure-responsibilities were confirmed by the relationships of pure water fluxtransmembrane pressure (PWF-TP) for the first time. The origin for this phenomenon was analyzed on the basis of membrane structure and material characteristics. The effects of SiO2 content on the structure and properties of membrane were investigated. The experimental results indicated that SiO2 in membrane created a great many interfacial micro-voids and played an important role in pressure-responsibility, PWF and rejection of membrane: with the increase of SiO2 content, the ability of membrane recovery weakened, PWF increased, and rejection decreased slightly.

  10. Structure-activity relationship of crustacean peptide hormones.

    Science.gov (United States)

    Katayama, Hidekazu

    2016-01-01

    In crustaceans, various physiological events, such as molting, vitellogenesis, and sex differentiation, are regulated by peptide hormones. To understanding the functional sites of these hormones, many structure-activity relationship (SAR) studies have been published. In this review, the author focuses the SAR of crustacean hyperglycemic hormone-family peptides and androgenic gland hormone and describes the detailed results of our and other research groups. The future perspectives will be also discussed.

  11. Structure-activity relationships of benzothiazole GPR35 antagonists.

    Science.gov (United States)

    Abdalhameed, Manahil M; Zhao, Pingwei; Hurst, Dow P; Reggio, Patricia H; Abood, Mary E; Croatt, Mitchell P

    2017-02-01

    The first structure-activity relationships for a benzothiazole scaffold acting as an antagonist at GPR35 is presented. Analogues were designed based on a lead compound that was previously determined to have selective activity as a GPR35 antagonist. The synthetic route was modular in nature to independently explore the role of the middle and both ends of the scaffold. The activities of the analogues illustrate the importance of all three segments of the compound.

  12. Relationship between molecular cloud structure and density PDFs

    CERN Document Server

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

    2013-01-01

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

  13. Synthetic and structure-activity relationship of insecticidal bufadienolides.

    Science.gov (United States)

    Hidayat, Ace Tatang; Zainuddin, Achmad; Dono, Danar; Hermawan, Wawan; Hayashi, Hideo; Supratman, Unang

    2014-07-01

    A new synthetic analog of bufadienolide, methyl isobryophyllinate A (1), and a known synthetic analog, methyl isobersaldegenate-1,3,5-orthoacetate (2), were obtained by methanolysis of bryophyllin A (3) and bersaldegenin-1,3,5-orthoacetate (5) in basic solution. Structure-insecticidal activity relationship studies revealed both orthoacetate and alpha-pyrone moieties seemed to be essential structural elements for exhibiting insecticidal activity, whereas oxygenated substituents in the C ring enhanced the insecticidal activity against the third instar larvae of silkworm (Bombyx mori).

  14. Relationship Between Soil Properties and Different Fractions of Soil Hg

    Institute of Scientific and Technical Information of China (English)

    WUHONGTAO; YUGUIFEN; 等

    2001-01-01

    Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing,China,Results showed that clay(<2m) could increase water-soluble Hg(r=0.700*).Soil organic matter (OM) could enhance the increase of elemental Hg(r=0.674*),The higher the base saturation percentage (BSP) ,the more the residual Hg(R=0.684*) .Organic Hg,the sum of said-soluble organic He and alkali-soluble Hg,was positively affected by silt(2-20μm)but negatively affected by pH,with the direct path coefficients amounting to 1.0487 and 0.5121,respectively .The positive effect of OM and negative effect of BSP on organic Hg were the most significant ,with the direct path coefficients being 0.7614 and -0.8527,respectively. The indirect effect of clay(<2μm) iva BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) via BSP (path coefficient=0.4186) was the highest,showing that the real influencing factor in the effect of clay(<2μm) on acid-soluble organic Hw was BSP.since the available Hg fraction,water-soluble Hg,was positively affected by soil clay content,and the quite immobile and not bioavailable residual Hg by soil BSP,suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

  15. Structure and property correlations in FeS

    Science.gov (United States)

    Kuhn, S. J.; Kidder, M. K.; Parker, D. S.; dela Cruz, C.; McGuire, M. A.; Chance, W. M.; Li, Li; Debeer-Schmitt, L.; Ermentrout, J.; Littrell, K. C.; Eskildsen, M. R.; Sefat, A. S.

    2017-03-01

    For iron-sulfide (FeS), we investigate the correlation between the structural details, including its dimensionality and composition, with its magnetic and superconducting properties. We compare, theoretically and experimentally, the two-dimensional (2D) layered tetragonal ("t-FeS") phase with the 3D hexagonal ("h-FeS") phase. X-ray diffraction reveals iron-deficient chemical compositions of t-Fe0.93(1)S and h-Fe0.84(1)S that show no low-temperature structural transitions. First-principles calculations reveal a high sensitivity of the 2D structure to the electronic and magnetic properties, predicting marginal antiferromagnetic instability for our compound (sulfur height of zS = 0.252) with an ordering energy of about 11 meV/Fe, while the 3D phase is magnetically stable. Experimentally, h-Fe0.84S orders magnetically well above room temperature, while t-Fe0.93S shows coexistence of antiferromagnetism at TN = 116 and filamentary superconductivity below Tc = 4 K. Low temperature neutron diffraction data reveals antiferromagnetic commensurate ordering with wave vector km = (0.25,0.25,0) and 0.46(2) μB/Fe. Additionally, neutron scattering measurements were used to find the particle size and iron vacancy arrangement of t-FeS and h-FeS. The structure of iron sulfide has a delicate relationship with the superconducting transition; while our sample with a = 3.6772(7) Å is a filamentary superconductor coexisting with an antiferromagnetic phase, previously reported samples with a > 3.68 Å are bulk superconductors with no magnetism, and those with a ≈ 3.674 Å show magnetic properties.

  16. 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.

  17. On Structure and Properties of Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Zbigniew H. Stachurski

    2011-09-01

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

  18. 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...

  19. Structure–property relationships of iron–hydroxyapatite ceramic matrix nanocomposite fabricated using mechanosynthesis method

    Energy Technology Data Exchange (ETDEWEB)

    Nordin, Jamillah Amer [Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310 (Malaysia); Prajitno, Djoko Hadi [Nuclear Technology Center for Materials and Radiometry, National Nuclear Energy, Bandung 40132 (Indonesia); Saidin, Syafiqah [Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, Johor Bahru 81310 (Malaysia); Nur, Hadi, E-mail: hadi@kimia.fs.utm.my [Centre for Sustainable Nanomaterials, Ibnu Sina Institute for Scientific and Industrial Research, Universiti Teknologi Malaysia, Johor Bahru 81310 (Malaysia); Department of Physics, Institut Sains dan Teknologi Nasional, Jl. Moh. Kahfi II, Jagakarsa, Jakarta Selatan 12640 (Indonesia); Hermawan, Hendra, E-mail: hendra.hermawan@gmn.ulaval.ca [Department of Mining, Metallurgical and Materials Engineering & CHU de Québec Research Center, Laval University, Québec City G1V 0A6 (Canada)

    2015-06-01

    Hydroxyapatite (HAp) is an attractive bioceramics due to its similar composition to bone mineral and its ability to promote bone–implant interaction. However, its low strength has limited its application as load bearing implants. This paper presented a work focusing on the improvement of HAp mechanical property by synthesizing iron (Fe)-reinforced bovine HAp nanocomposite powders via mechanosynthesis method. The synthesis process was performed using high energy milling at varied milling time (3, 6, 9, and 12 h). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM). Its mechanical properties were investigated by micro-Vicker's hardness and compression tests. Results showed that milling time directly influenced the characteristics of the nanocomposite powders. Amorphous BHAp was formed after 9 and 12 h milling in the presence of HPO{sub 4}{sup 2−} ions. Continuous milling has improved the crystallinity of Fe without changing the HAp lattice structure. The nanocomposite powders were found in spherical shape, agglomerated and dense after longer milling time. The hardness and Young's modulus of the nanocomposites were also increased at 69% and 66%, respectively, as the milling time was prolonged from 3 to 12 h. Therefore, the improvement of the mechanical properties of nanocomposite was attributed to high Fe crystallinity and homogenous, dense structure produced by mechanosynthesis - Highlights: • Improvement of mechanical properties of HAp bioceramics by mechanosynthesis method • Structure–property relationship of iron–hydroxyapatite ceramic matrix nanocomposite • Milling time influenced the properties of iron–hydroxyapatite ceramic matrix nanocomposite.

  20. Revisiting HOPG superlattices: Structure and conductance properties

    Science.gov (United States)

    Patil, Sumati; Kolekar, Sadhu; Deshpande, Aparna

    2017-04-01

    Superlattices observed on highly oriented pyrolytic graphite (HOPG) have been studied extensively by scanning tunnelling microscopy (STM). The interest in the study of graphite superlattices has seen a resurgence since the discovery of graphene. Single layer graphene, bilayer graphene, and few layer graphene can now be grown on different substrates. The adherence of graphene to various substrates often leads to a periodic out-of-plane modulation and superlattices due to lattice mismatch. In this paper, we report STM imaging and scanning tunnelling spectroscopy (STS) of different kinds of superlattices on HOPG characterized by a variation in lattice periodicities. Our study also shows evidence of the displacement of the topmost HOPG layer by scanning different areas of the same superlattice. A correlation between the lattice periodicity with its conductance properties is derived. The results of this work are important for understanding the origin of the superlattice structure on HOPG. Investigation of such superlattices may open up possible ways to modify two dimensional electron systems to create materials with tailored electronic properties.

  1. 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.

  2. Property taxes and economic development. An approach to the relationship between property taxes and the investment of Antioquia's municipalities

    Directory of Open Access Journals (Sweden)

    Santiago Tobón Zapata

    2013-06-01

    Full Text Available This paper discusses the relationship between the levels of investment in health and education made by the municipalities and the collection of property taxes. A data panel methodology was used with a sample of 97 municipalities in the department of Antioquia (Colombia for the period 2000 - 2008. According to the results, it is possible to conclude that there is no relationship between the levels of autonomous investment in education and the collection of property taxes. On the other hand, in relation to health investments, a negative relationship was found between property tax collection and autonomous investment in health. Finally, in addition to the initial scope proposed, a positive relationship was shown between the collection of property taxes and investments in the development of roads and infrastructure.

  3. Relationships between structures and performance of SOFC anodes

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg; Jacobsen, Torben

    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...... 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...

  4. Relationship between Methane Content in Siberian Permafrost and Soil Properties

    Science.gov (United States)

    Brouchkov, A.; Fukuda, M.

    2004-05-01

    Methane is one of the greenhouse gases among other gases, and it is important to identify sources of methane. Permafrost deposits in Siberia contain large amounts of methane in air bubbles, and there is a high possibility of permafrost thawing due to climatic warming. However, distribution of methane in frozen deposits is still poorly known. It should be related to soil content and properties. Therefore, present knowledge of permafrost soils collected by a number of studies can be a key to understanding of methane distribution; the subject was never discussed before. Air bubbles from frozen soil and ice were sampled at the uppermost layers of permafrost from the depth up to 5 and more m in Eastern Siberia. The major study site was located in valley of Lena River. The permafrost samples were obtained by shallow borehole drilling. Soil composition, density and water content were also measured as well as the concentration of gases in the air bubbles. Total number of air samples was about 200. Air from soils was analyzed by gas chromatograph. No certain relationship between methane concentration and depth was found. Highly concentrated methane occurs in permafrost at different depths. Ice wedges contain less methane than frozen soils in general. There no obvious tendencies between water contents and values of concentrations of both methane and carbon dioxide were found. Methane content increases in general with water content increase, and carbon dioxide content becomes lower; however, in some cases the tendency is opposite, if the concentration is high (up to 70 ppt). Data collected on ion (salt) content is limited, but methane content rises with salinization increase. Low methane content and low salinization in the same time could be connected to possible thawing of permafrost when soil could be washed. Frozen soils containing large amounts of methane and being thawed have average pH about 7-9. The more density and age of frozen soil the more methane content; it could

  5. 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.

  6. Multiscale regression modeling in mouse supraspinatus tendons reveals that dynamic processes act as mediators in structure-function relationships.

    Science.gov (United States)

    Connizzo, Brianne K; Adams, Sheila M; Adams, Thomas H; Jawad, Abbas F; Birk, David E; Soslowsky, Louis J

    2016-06-14

    Recent advances in technology have allowed for the measurement of dynamic processes (re-alignment, crimp, deformation, sliding), but only a limited number of studies have investigated their relationship with mechanical properties. The overall objective of this study was to investigate the role of composition, structure, and the dynamic response to load in predicting tendon mechanical properties in a multi-level fashion mimicking native hierarchical collagen structure. Multiple linear regression models were investigated to determine the relationships between composition/structure, dynamic processes, and mechanical properties. Mediation was then used to determine if dynamic processes mediated structure-function relationships. Dynamic processes were strong predictors of mechanical properties. These predictions were location-dependent, with the insertion site utilizing all four dynamic responses and the midsubstance responding primarily with fibril deformation and sliding. In addition, dynamic processes were moderately predicted by composition and structure in a regionally-dependent manner. Finally, dynamic processes were partial mediators of the relationship between composition/structure and mechanical function, and results suggested that mediation is likely shared between multiple dynamic processes. In conclusion, the mechanical properties at the midsubstance of the tendon are controlled primarily by fibril structure and this region responds to load via fibril deformation and sliding. Conversely, the mechanical function at the insertion site is controlled by many other important parameters and the region responds to load via all four dynamic mechanisms. Overall, this study presents a strong foundation on which to design future experimental and modeling efforts in order to fully understand the complex structure-function relationships present in tendon.

  7. Crystal structures and dynamical properties of dense CO2.

    Science.gov (United States)

    Yong, Xue; Liu, Hanyu; Wu, Min; Yao, Yansun; Tse, John S; Dias, Ranga; Yoo, Choong-Shik

    2016-10-04

    Structural polymorphism in dense carbon dioxide (CO2) has attracted significant attention in high-pressure physics and chemistry for the past two decades. Here, we have performed high-pressure experiments and first-principles theoretical calculations to investigate the stability, structure, and dynamical properties of dense CO2 We found evidence that CO2-V with the 4-coordinated extended structure can be quenched to ambient pressure below 200 K-the melting temperature of CO2-I. CO2-V is a fully coordinated structure formed from a molecular solid at high pressure and recovered at ambient pressure. Apart from confirming the metastability of CO2-V (I-42d) at ambient pressure at low temperature, results of ab initio molecular dynamics and metadynamics (MD) simulations provided insights into the transformation processes and structural relationship from the molecular to the extended phases. In addition, the simulation also predicted a phase V'(Pna21) in the stability region of CO2-V with a diffraction pattern similar to that previously assigned to the CO2-V (P212121) structure. Both CO2-V and -V' are predicted to be recoverable and hard with a Vicker hardness of ∼20 GPa. Significantly, MD simulations found that the CO2 in phase IV exhibits large-amplitude bending motions at finite temperatures and high pressures. This finding helps to explain the discrepancy between earlier predicted static structures and experiments. MD simulations clearly indicate temperature effects are critical to understanding the high-pressure behaviors of dense CO2 structures-highlighting the significance of chemical kinetics associated with the transformations.

  8. Structural Properties of Green Tea Catechins.

    Science.gov (United States)

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

    2015-10-08

    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.

  9. High-pressure structural properties of tetramethylsilane

    Science.gov (United States)

    Zhen-Xing, Qin; Xiao-Jia, Chen

    2016-02-01

    High-pressure structural properties of tetramethylsilane are investigated by synchrotron powder x-ray diffraction at pressures up to 31.1 GPa and room temperature. A phase with the space group of Pnma is found to appear at 4.2 GPa. Upon compression, the compound transforms to two following phases: the phase with space groups of P21/c at 9.9 GPa and the phase with P2/m at 18.2 GPa successively via a transitional phase. The unique structural character of P21/c supports the phase stability of tetramethylsilane without possible decomposition upon heavy compression. The appearance of the P2/m phase suggests the possible realization of metallization for this material at higher pressure. Project supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China (Grant No. 708070), the Fundamental Research Funds for the Central Universities, South China University of Technology (Grant No. 2014ZZ0069), the National Natural Science Foundation of China (Grant No. 51502189), and the Doctoral Project of Taiyuan University of Science and Technology, China (Grant No. 20132010).

  10. 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

  11. 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.

  12. 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...... attachment structures....

  13. Enhancing the value of commodity polymers: Part 1. Structure-property relationships in composite materials based on maleated polypropylene/inorganic phosphate glasses. Part 2. New value-added applications for polyesters

    Science.gov (United States)

    Gupta, Mohit

    The first part of the thesis (Chapters 2 & 3) describes a new class of organic polymer/inorganic glass composite materials with property improvements that are impossible to achieve with classical polymer blends or composites. These materials exhibit good processability, superior mechanical performance, good thermal stability, and have excellent gas barrier properties. Low glass transition temperature phosphate glasses (Pglass) are used as inorganic fillers and slightly maleated polypropylene is used as the organic polymer matrix. The Pglass, which was dispersed as spherical droplets in the unoriented composites can be elongated into high aspect ratio platelets during the biaxial stretching process. Biaxially oriented films exhibited a brick wall type microstructure with highly aligned inorganic platelets in a ductile organic matrix and the oxygen barrier properties are significantly improved due to presence of Pglass platelets as impermeable inclusions. Mechanical properties of the biaxially oriented films showed significant improvements compared to neat polymer due to uniform dispersion of the Pglass platelets. Properly dispersed and aligned platelets have proven to be very effective for increasing the composite modulus. These developed materials therefore show promise to help fulfill the ever increasing demand for new advanced materials for a wide variety of advanced packaging applications because of their gas barrier properties, flexibility, transparency, mechanical strength and performance under humid conditions. The second part of the thesis (Chapters 4 & 5) describes new value-added applications for polyesters. Chapter 4 reports a novel process for the decolorization of green and blue colored PET bottle flakes using hydrogen peroxide. The decolorized flakes were characterized for color, intrinsic viscosity values. Decolorized flakes exhibited color values similar to those of colorless recycled PET and even though IV values decreased, bleached flakes still

  14. 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.

  15. Model identification for DNA sequence-structure relationships.

    Science.gov (United States)

    Hawley, Stephen Dwyer; Chiu, Anita; Chizeck, Howard Jay

    2006-11-01

    We investigate the use of algebraic state-space models for the sequence dependent properties of DNA. By considering the DNA sequence as an input signal, rather than using an all atom physical model, computational efficiency is achieved. A challenge in deriving this type of model is obtaining its structure and estimating its parameters. Here we present two candidate model structures for the sequence dependent structural property Slide and a method of encoding the models so that a recursive least squares algorithm can be applied for parameter estimation. These models are based on the assumption that the value of Slide at a base-step is determined by the surrounding tetranucleotide sequence. The first model takes the four bases individually as inputs and has a median root mean square deviation of 0.90 A. The second model takes the four bases pairwise and has a median root mean square deviation of 0.88 A. These values indicate that the accuracy of these models is within the useful range for structure prediction. Performance is comparable to published predictions of a more physically derived model, at significantly less computational cost.

  16. 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.

  17. Hierarchical relationship between bone traits and mechanical properties in inbred mice.

    Science.gov (United States)

    Jepsen, Karl J; Akkus, Ozan J; Majeska, Robert J; Nadeau, Joseph H

    2003-02-01

    Osteoporotic fracture incidence and underlying risk factors like low peak bone mass are heritable, but the genetic basis of osteoporosis remains poorly understood. Based on beam theory, stating that mechanical properties of a structure depend on both the amount and quality of the constituent materials, we investigated the relationship between whole bone mechanical properties and a set of morphological and compositional traits in femurs of eight inbred mouse strains. K-means cluster analysis revealed that individual femora could be classified reliably according to genotype based on the combination of bone area (tissue amount), moment of inertia (tissue distribution), and ash content (tissue quality). This trait combination explained 66-88% of the inter-strain variability in four whole-bone mechanical properties that describe all aspects of the failure process, including measures of brittleness. Stiffness and maximum load were functionally associated with cortical area, while measures of brittleness were associated with ash content. In contrast, work-to-failure was not directly related to a single trait but depended on a combination of trait magnitudes. From these findings, which were entirely consistent with established mechanical theory, we developed a hierarchical paradigm relating the mechanical properties that define bone fragility with readily measurable phenotypic traits that exhibit strong heritability. This paradigm will help guide the search for genes that underlie fracture susceptibility and osteoporosis. Moreover, because the traits we examined are measurable with non-invasive means, this approach may also prove directly applicable to osteoporosis risk assessment.

  18. Study on relationships of electromagnetic band structures and left/right handed structures

    Institute of Scientific and Technical Information of China (English)

    GAO Chu; CHEN ZhiNing; WANG YunYi; YANG Ning

    2007-01-01

    Two types of dual periodic circuits are introduced. The distributions of passbands and stopbands are generated from their dispersion relationships. Based on the study, Brillouin diagrams of three representative special cases are drawn; S parameters of these three cases are simulated by Aglient ADS; the S parameters of one of the three cases are verified by an experiment. The phase characteristics are compared with those generated from the dispersion relationship. The theoretical analysis and the experimental verification show that both types of the periodic structures can behave as electromagnetic band gap (EBG) structures, right-handed structures (RHS), and left-handed structures (LHS), when they operate at different frequency ranges. Thus, the possibility of a physical structure showing these three different characteristics at different frequency ranges is proven.

  19. Social status moderates the relationship between facial structure and aggression.

    Science.gov (United States)

    Goetz, Stefan M M; Shattuck, Kraig S; Miller, Robert M; Campbell, Jocelyn A; Lozoya, Elianna; Weisfeld, Glenn E; Carré, Justin M

    2013-11-01

    A growing body of evidence has linked individual differences in facial structure-in particular, the facial width-to-height ratio (FWHR)-to social behaviors, including aggression, cheating, and nonreciprocation of trust. In the research reported here, we extended this work by demonstrating that the association between FWHR and aggression is moderated by subjective and objective measures of social status. In Study 1 (N = 237 college students), FWHR was positively correlated with aggressive behavior, but only among men reporting relatively low social status. In Study 2 (N = 891 professional hockey players), FWHR was positively correlated with penalty minutes, but only among players who earned relatively low salaries. Collectively, these studies provide compelling evidence for the role of social status in moderating the relationship between facial structure and aggression, indicating that FWHR is a robust predictor of aggressive behavior, but only in the context of relatively low social status.

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

    Directory of Open Access Journals (Sweden)

    Krzyńska 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.

  1. Synthesis, structure and biological properties of active spirohydantoin derivatives

    Directory of Open Access Journals (Sweden)

    Lazić Anita M.

    2016-01-01

    Full Text Available Spirohidantoins represent an pharmacologically important class of heterocycles since many derivatives have been recognized that display interesting activities against a wide range of biological targets. First synthesis of cycloalkanespiro-5-hydantoins was performed by Bucherer and Lieb 1934 by the reaction of cycloalkanone, potassium cyanide and ammonium-carbonate at reflux in a mixture of ethanol and water. QSAR (Quantitative Structure-Activity Relationship studies showed that a wide range of biological activities of spirohydantoin derivatives strongly depend upon their structure. This paper describes different methods of synthesis of spirohydantoin derivatives, their physico-chemical properties and biological activity. It emphasizes the importance of cycloalkanespiro-5-hydantoins with anticonvulsant, antiproliferative, antipsychotic, antimicrobial and antiinflammatory properties as well as their importance in the treatment of diabetes. Numerous spirohydantoin compounds exhibit physiological activity such as serotonin and fibrinogen antagonist, inhibitors of the glycine binding site of the NMDA receptor also, antagonist of leukocyte cell adhesion, acting as allosteric inhibitors of the protein-protein interactions. Some spirohydantoin derivatives have been identified as antitumor agents. Their activity depends on the substituent presented at position N-3 of the hydantoin ring and increases in order alkene > ester > ether. Besides that, compounds that contain two electron withdrawing groups (e.g. fluorine or chlorine on the third and fourth position of the phenyl ring are better antitumor agents than compounds with a single electron withdrawing group. [Projekat Ministarstva nauke Republike Srbije, br. 172013

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

    Energy Technology Data Exchange (ETDEWEB)

    Toda-Caraballo, Isaac [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Galindo-Nava, Enrique I. [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Delft University of Technology, Mekelweg 2, Delft 2628 CD (Netherlands); Rivera-Díaz-del-Castillo, Pedro E.J., E-mail: pejr2@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

    2013-07-25

    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.

  3. Structure-activity relationship studies of citalopram derivatives

    DEFF Research Database (Denmark)

    Larsen, M Andreas B; Plenge, Per; Andersen, Jacob;

    2016-01-01

    towards the S2 site. EXPERIMENTAL APPROACH: We performed a systematic structure-activity relationship study based on the scaffold of citalopram and the structurally closely related congener, talopram, that shows low-affinity S1 binding in SERT. The role of the four chemical substituents, which distinguish......-activity relationship study revealed a di-methyl citalopram, which binds to the S1 site with an affinity of 6.4 [4.7;8.8] μM (mean[SEM interval]) and shows an allosteric potency of 3.6 [3.3;3.8] μM, thus bearing ~2-fold selectivity for the allosteric site relative to the S1 site in SERT. CONCLUSIONS AND IMPLICATIONS....... The antidepressant drug citalopram displays high-affinity S1 binding and low-affinity S2 binding. To elucidate a possible therapeutic role of allosteric inhibition of SERT a drug that specifically targets the allosteric site is required. The purpose of this study was to find a compound bearing higher selectivity...

  4. Structures and Properties of Nanometer Size Materials Ⅲ. Structures and Physical Properties of Iron Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    李小华; 马美华

    2005-01-01

    Molecular dynamics computer simulation has been carded out to study the structure and physical properties of iron nanoparticles with 331 to 2133 Fe atoms or with diameter from 2.3 to 4.3 nm. The core of liquid nanodroplets has the similar structure of the bulk molten iron liquid that has an average coordination number around 10.5 and the packing density around 0.45, although the closest Fe-Fe distance is slightly longer in the bulk liquid. Most of the iron nanoparticles formed from the cooling of molten nanodroplets have the same body center cubic crystal structure as it was observed in the bulk under the normal temperature and pressure. Lattice contraction was observed for iron nanoparticles. An amorphous solid and an HCP like solid were obtained accidentally during the quenching runs on Fe331 nanoparticles. The physical properties of iron nanoparticles such as molar volume, density, thermal expansion coefficient, melting point, heat of fusion, heat capacity and diffusion coefficient were estimated based on the results obtained from this simulation. The dependence of physical properties on the nanoparticle sizes was addressed.

  5. Curdlan ester derivatives: synthesis, structure, and properties.

    Science.gov (United States)

    Marubayashi, Hironori; Yukinaka, Kazuyori; Enomoto-Rogers, Yukiko; Takemura, Akio; Iwata, Tadahisa

    2014-03-15

    A series of ester derivatives of curdlan, which is a β-(1 → 3)-D-glucan extracellularly produced by microorganism, with varying alkyl chain lengths (C2-C12) were synthesized by the heterogeneous reaction using trifluoroacetic anhydride. As a result, high-molecular-weight (Mw ≥ 6 × 10(5)) and fully-acylated curdlan was obtained with relatively high yield (>70%). Thermal stability of curdlan was greatly improved by esterification. Crystallization was observed for curdlan esters with C2-C6 side chains. Both Tg (170 → 50 °C) and Tm (290 → 170 °C) of curdlan esters decreased with increasing the side-chain length. By the increase in the side-chain carbon number, curdlan esters showed lower Young's modulus and tensile strength, and larger elongation at break. Thus, material properties of curdlan esters can be controlled by changing the side-chain length. It was found that the increase of the side-chain length resulted in the decrease of crystallinity and the change of crystal structures.

  6. 缓蚀剂分子结构与抗硫性能及其缓蚀机理研究%RELATIONSHIP BETWEEN CHEMICAL MOLECULAR STRUCTURE AND ANTI-SULFUR PROPERTIES AND INHIBITION MECHANISM OF CORROSION INHIBITORS

    Institute of Scientific and Technical Information of China (English)

    刘月学; 刘烈炜; 董猛; 张大同

    2012-01-01

    用饱和H_2S/CO_2失重法、高压H_2S/CO_2动态失重法、原子力显微镜(AFM)、环境扫描电镜(SEM)和X射线能量色散光谱(EDX)研究了咪唑啉衍生物、曼尼希碱、吡啶季铵盐、喹啉季铵盐和新稠杂环季铵盐5种不同分子结构缓蚀剂对N80钢的抗硫性能。结果表明5种缓蚀剂对N80钢的抗硫性能均随缓蚀剂浓度的增加而增强,各缓蚀剂的抗硫性能优劣顺序为:新稠杂环季铵盐〉喹啉季铵盐〉吡啶季铵盐〉咪唑啉衍生物〉曼尼希碱。静电吸附作用较强、空间位阻效应较小且中心吸附原子的电子云密度较大的缓蚀剂抗硫效果更好,其缓蚀机理主要是有效抑制CO_2/Cl~-腐蚀且促使试片表面生成致密的硫化物保护膜。%The inhibitive properties of five kinds of corrosion inhibitors,which contain imidazoline derivative, mannich base,pyridine quaternary ammonium salt,quinoline quaternary ammonium salt and a new fused heterocycle quaternary ammonium salt were studied by means of mass loss of saturated H_2S/CO_2 and dynamic rotating with high-pressure of H_2S/CO_2,atomic force microscopy(AFM),environmental scanning electron microscope (SEM) and energy dispersive X-ray(EDX) analysis on N80 steel.The results showed that inhibitive properties of five kinds of inhibitors enhanced with the increase of their concentration.The excellent order of the inhibitors was as followed:the new fused heterocycle quaternary ammonium saltquinoline quaternary ammonium saltpyridine quaternary ammonium saltimidazoline derivativemannich base.Corrosion inhibitor which had stronger electrostatic adsorption,smaller steric hindrance effect and larger electron density of the adatom had the better anti-sulfur properties.The inhibition mechanism of corrosion inhibitor was to inhibit the corrosion of CO_2/C1~- and spur the formation of the compact sulfide film.

  7. Emerging Relationships Between Structure and Ecological Function in the Landscape

    Directory of Open Access Journals (Sweden)

    Robert Brown

    2004-06-01

    Full Text Available The concepts of landscape ecology are theoretically applicable to landscapes anywhere in the world. Much information has been generated relating sizes, shapes, and composition of patches and corridors in the landscape to their ecological function. Many patterns related to ecological processes are emerging that can be applied with increasing confidence in landscape planning and design. In this context, we developed a comprehensive approach that makes use of three-dimensional (3-D models to describe visually the structural properties of landscape elements. This approach may be used by landscape architects so that the patterns they create also have an appropriate ecological function.

  8. Structure-Activity Relationship Analysis of the Thermal Stabilities of Nitroaromatic Compounds Following Different Decomposition Mechanisms.

    Science.gov (United States)

    Li, Jiazhong; Liu, Huanxiang; Huo, Xing; Gramatica, Paola

    2013-02-01

    The decomposition behavior of energetic materials is very important for the safety problems concerning their production, transportation, use and storage, because molecular decomposition is intimately connected to their explosive properties. Nitroaromatic compounds, particularly nitrobenzene derivatives, are often considered as prototypical energetic molecules, and some of them are commonly used as high explosives. Quantitative structure-activity relationship (QSAR) represents a potential tool for predicting the thermal stability properties of energetic materials. But it is reported that constructing general reliable models to predict their stability and their potential explosive properties is a very difficult task. In this work, we make our efforts to investigate the relationship between the molecular structures and corresponding thermal stabilities of 77 nitrobenzene derivatives with various substituent functional groups (in ortho, meta and/or para positions). The proposed best MLR model, developed by the new software QSARINS, based on Genetic Algorithm for variable selection and with various validation tools, is robust, stable and predictive with R(2) of 0.86, QLOO (2) of 0.79 and CCC of 0.90. The results indicated that, though difficult, it is possible to build predictive, externally validated QSAR models to estimate the thermal stability of nitroaromatic compounds.

  9. 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…

  10. Assessing adult attachment across different contexts: validation of the Portuguese version of the experiences in Close Relationships-Relationship Structures questionnaire.

    Science.gov (United States)

    Moreira, Helena; Martins, Teresa; Gouveia, Maria João; Canavarro, Maria Cristina

    2015-01-01

    The Experiences in Close Relationships-Relationship Structures questionnaire (ECR-RS) is one of the most recent measures of adult attachment. This instrument provides a contextual assessment of attachment-related anxiety and avoidance by measuring these dimensions in various close relationships (mother, father, partner, friend). To further explore its psychometric properties and cross-cultural adequacy, this study presents the validation of the ECR-RS in a sample of Portuguese community individuals (N = 236). The Portuguese version showed adequate reliability and construct validity. The original 2-factor structure was confirmed through confirmatory factor analysis. The ECR-RS is a psychometrically robust measure of attachment, representing an important advance in the measurement of adult attachment.

  11. 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.

  12. 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

  13. Minimum-free-energy distribution of RNA secondary structures: Entropic and thermodynamic properties of rare events

    Science.gov (United States)

    Wolfsheimer, S.; Hartmann, A. K.

    2010-08-01

    We study the distribution of the minimum free energy (MFE) for the Turner model of pseudoknot free RNA secondary structures over ensembles of random RNA sequences. In particular, we are interested in those rare and intermediate events of unexpected low MFEs. Generalized ensemble Markov-chain Monte Carlo methods allow us to explore the rare-event tail of the MFE distribution down to probabilities such as 10-70 and to study the relationship between the sequence entropy and structural properties for sequence ensembles with fixed MFEs. Entropic and structural properties of those ensembles are compared with natural RNA of the same reduced MFE ( z score).

  14. The measurement properties of mentoring relationship quality scales for mentoring programs.

    Science.gov (United States)

    Ferro, Annalise; Wells, Samantha; Speechley, Kathy Nixon; Lipman, Ellen; DeWit, David

    2014-10-01

    The measurement properties of two new scales designed to measure global and engagement mentoring relationship quality (Global Mentoring Relationship Quality Scale and Quality of Mentoring Relationship Engagement Scale) were examined among 272 mentors, 491 children, and 554 parents participating in Big Brothers Big Sisters community mentoring programs across Canada. Results demonstrated their unidimensionality, moderate convergent validity, good external validity, and weak-to-moderate reporter concordance. Longitudinal analyses demonstrated good predictive validity of mentor and parent mentoring relationship quality scales with respect to predicting mentoring relationship status.

  15. New Descriptors of Amino Acids and Its Applications to Peptide Quantitative Structure-activity Relationship

    Institute of Scientific and Technical Information of China (English)

    SHU Mao; HUO Dan-Qun; MEI Hua; LIANG Gui-Zhao; ZHANG Mei; LI Zhi-Liang

    2008-01-01

    A new set of descriptors, HSEHPCSV (component score vector of hydrophobic, steric, and electronic properties together with hydrogen bonding contributions), were derived from principal component analyses of 95 physicochemical variables of 20 natural amino acids separately according to different kinds of properties described, namely, hydrophobic, steric, and electronic properties as well as hydrogen bonding contributions. HSEHPCSV scales were then employed to express structures of angiotensin-converting enzyme inhibitors, bitter tasting thresholds and bactericidal 18 peptide, and to construct QSAR models based on partial least square (PLS). The results obtained are as follows: the multiple correlation coefficient (R2cum) of 0.846, 0.917 and 0.993, leave-one-out cross validated Q2cum of 0.835, 0.865 and 0.899, and root-mean-square error for estimated error (RMSEE) of 0.396, 0.187and 0.22, respectively. Satisfactory results showed that, as new amino acid scales, data of HSEHPCSV may be a useful structural expression methodology for the studies on peptide QSAR (quantitative structure-activity relationship) due to many advantages such as plentiful structural information, definite physical and chemical meaning and easy interpretation.

  16. 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.

  17. Structure and Relationships of University Instructors’ Achievement Goals

    Directory of Open Access Journals (Sweden)

    Martin eDaumiller

    2016-03-01

    Full Text Available The present study examines the achievement goals of university instructors, particularly the structure of such goals, and their relationship to biographic characteristics, other aspects of instructors’ motivation, and teaching quality. Two hundred and fifty-one university instructors (184 without PhD, 97 with PhD, thereof 51 full professors; 146 males, 92 females answered a questionnaire measuring achievement goals, self-efficacy, and enthusiasm in altogether 392 courses. Teaching quality was assessed using reports from 9,241 students who were attending these courses. Confirmatory factor analyses revealed mastery, performance approach, performance avoidance, work avoidance, and relational goals as being distinguishable from each other. Distinct relationships were found between different instructors’ achievement goals, and gender, age, and career status as well as self-efficacy and enthusiasm. Hierarchical linear models suggested positive associations of instructors’ mastery goals with teaching quality, while negative associations were indicated for performance avoidance goals and work avoidance goals in relation to teaching quality. Exploratory analyses conducted due to a quite large correlation between performance approach and performance avoidance goals indicated that for university instructors, differentiating performance goals into appearance and normative components might also be adequate. All in all, the study highlights the auspiciousness of the theoretical concept of university instructors’ achievement goals and contributes to making it comprehensively accessible.

  18. Relationship between silver concentration with microstructural and mechanical properties of rolled AlZn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Valdez, S., E-mail: svaldez@fis.unam.mx [Instituto de Ciencias Fisicas-Universidad Nacional Autonoma de Mexico, Av. Universidad S/N, Col. Chamilpa, 062210 Cuernavaca, Morelos (Mexico); Perez, R.; Rodriguez-Diaz, R.A. [Instituto de Ciencias Fisicas-Universidad Nacional Autonoma de Mexico, Av. Universidad S/N, Col. Chamilpa, 062210 Cuernavaca, Morelos (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Eje central Lazaro Cardenas 152, Mexico D.F. 07730 (Mexico); Casolco, S.R. [Instituto Tecnologico y de Estudios Superiores de Monterrey, Campus Puebla, Via Atlixcayotl 2301. Puebla, Pue. 2800 (Mexico)

    2010-05-25

    The relationship of Ag addition on microstructural and mechanical properties of rolled AlZn alloy was investigated. AlZn alloys were prepared by metal mould casting method and the Ag addition was done by Vortex technique. Microstructural characterization of AlZnAg specimens was analyzed by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Results show that the phases of the as-cast state alloy are solid solution zinc-rich hexagonal close-packed (hcp) crystal structure, named {eta}-phase and {alpha}-Al solid solution with Zn dissolved into the matrix. The silver concentration in AlZn alloy influences the volume of AgZn{sub 3} precipitates. The mechanical properties, especially the flow stress and elongation of the alloy were improved by the Ag addition. The Vortex method was used in order to diminish the process cost, generating an alloy with homogenous microstructure, less casting porosity and better mechanical properties.

  19. Structure-Activity Relationship of Fluoroquinolones Against K. pneumoniae

    Science.gov (United States)

    Li, Xiao-hong; Zhang, Rui-zhou; Cheng, Xin-lu; Yang, Xiang-dong

    2007-04-01

    The structure-activity relationship of fluoroquinolones, which show anti-K. pneumoniae activity, was studied by using principal component analysis (PCA) and hierarchical cluster analysis (HCA). The PCA results showed that the lowest unoccupied molecular orbital energy, energy difference between the highest occupied and the lowest unoccupied molecular orbital, dipole moment, net atomic charge on atom I, molecular polarizability, partition coefficient and molecular refractivity of these compounds are responsible for the separation between high-activity and low-activity groups. The HCA results were similar to those obtained with PCA. By using the chemometric results, four synthetic compounds were analyzed through PCA and HCA, and three of them are proposed as active molecules against K. pneumoniae which is consistent with the results of clinical experiments. The methodologies of PCA and HCA provide a reliable rule for classifying new fluoroquinolones with anti-K. pneumoniae activity.

  20. Structure-biological activity relationship of synthetic trihydroxilated chalcones

    Directory of Open Access Journals (Sweden)

    Devia Cristina M.

    1998-01-01

    Full Text Available The bacteriostatic activity of 2?,4?,2-trihydroxychalcone; 2?,4?,3-trihydroxychalcone and 2?,4?,4-trihydroxychalcone, prepared by condensation of 2,4-dihydroxyacetophenone and benzaldehyde substituted, against Staphylococcus aureus ATCC 25923 was assayed by agar plate method. The three compounds presented important inhibition halos. In order to elucidate structure-activity relationships, the minimal inhibitory concentrations against S. aureus were determined by the broth dilution method and the results obtained were compared to that of 2',4'-dihydroxychalcone. The sequence observed was: MIC 2?,4?,3-(OH3 > MIC 2?,4?-(OH2 > MIC 2?,4?,4-(OH3 > > MIC 2?,4?,2-(OH3. These results showed that the introduction of an electron donating group (-OH in the aromatic B-ring causes an increase in bioactivity, and that the intensity of action depends on the position of the OH substitute.

  1. Structure-activity relationship of endomorphins and their analogs

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To study the structure-activity relationship of endomorphins (EMs), the action of opioid receptor binding (AORB), analgesic activity and vasodilator effects of EMs and their eight analogs were investigated, which were prepared by rationally replacing the 2-/3-amino acid (Aa) of EMs. The results showed: (ⅰ) The 2-Aa was comparatively more related to the selectivity of EMs while the 3-Aa to their affinity; (ⅱ) the analgesia and vasodilatation of EMs and their analogs were not completely dictated by their AORB (in vitro), the action of [D-Pro2]EM-2 was unusual; (ⅲ) EMs lost their analgesia in the central nervous system and their vasodilatation in the circulatory system with different mechanisms; the former was due to the degradation of some peptidase, and the latter possibly due to the feedback inhibi-tion.

  2. Relationship between Ballistic Coefficient and Static Mechanical Properties for Armor Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The relationship between the ballistic coefficient and the static mechanical properties of armor materials was studied. The results show that the ballistic coefficient is determined by the strength, hardness and the toughness of materials. According to the Martel rule, the equation of the relationship between ballistic coefficient and static mechanical properties satisfies the following formula: . From the mixture law of composite, the prerequisite, for which ballistic coefficient has maximum to reinforcement volume fraction, is obtained by the following equation: .

  3. Relationship between the Physical Properties and Hand of Jean Fabric

    Directory of Open Access Journals (Sweden)

    Kawamura Atsushi

    2016-09-01

    Full Text Available We investigated the distinctive characteristics of jean fabrics (denim fabrics obtained from jeans and compared the physical properties and the hand. We used 13 kinds of jean fabric from commercial jeans and 26 other fabric types. The physical properties were measured using the Kawabata evaluation system, and the fabric hand was evaluated by 20 subjects using a semantic differential method. To characterise the hand of jean fabrics compared with other fabrics, we used principal component analysis and obtained three principal components. We found that jean fabrics were characterised by the second principal component, which was affected by feelings of thickness and weight. We further characterised the jean fabrics according to ‘softness & smoothness’ and ‘non-fullness’, depending on country of origin and type of manufacturer. The three principal components were analysed using multiple linear regression to characterise the components according to the physical properties. We explained the hand of fabrics including jean fabrics using its association with physical properties.

  4. Structural and electronic properties of hybrid silicon-germanium nanosheets

    Directory of Open Access Journals (Sweden)

    F. L. Pérez Sánchez

    2014-12-01

    Full Text Available Using first principles molecular calculations, based on the Density Functional Theory (DFT, structural and electronic properties of hybrid graphene—like silicon—germanium circular nanosheets of hexagonal symmetry are investigated. The exchange—correlation functional of Perdew—Wang (PW in the local spin density approximation (LSDA based on the pseudopotentials of Dolg—Bergnre is applied. The finite extension nanosheets are represented by the CnHm—like cluster model with mono—hydrogenated armchair edges. Changes of the physicochemical properties were analyzed to learn on the chemical composition. We have obtained that the corrugation of the hybrid nanosheets is maintained (with respect to the pristine nanosheets of Ge and Si and is more pronounced when there is a high percentage of germanium. Moreover, hybrid nanosheets have ionic bonds (polarity in the interval from 0.18 to 0.77 D and exhibit a semimetal behavior. Three types of chemical compositions are considered: 1 the one—one relationship, 2 formation of Ge dimers and 3 formation of Ge hexagons. In each case it is observed an increase in the chemical reactivity. Finally, analyzing the work function we conclude that in cases 1 and 2 the chemical compositions improve the efficiency of the field emission and thereby they could expand the scope of nanotechnology applications.

  5. Electronic structure and optical properties of monoclinic clinobisvanite BiVO4.

    Science.gov (United States)

    Zhao, Zongyan; Li, Zhaosheng; Zou, Zhigang

    2011-03-14

    Monoclinic clinobisvanite bismuth vanadate is an important material with wide applications. However, its electronic structure and optical properties are still not thoroughly understood. Density functional theory calculations were adopted in the present work, to comprehend the band structure, density of states, and projected wave function of BiVO(4). In particular, we put more emphasis upon the intrinsic relationship between its structure and properties. Based on the calculated results, its molecular-orbital bonding structure was proposed. And a significant phenomenon of optical anisotropy was observed in the visible-light region. Furthermore, it was found that its slightly distorted crystal structure enhances the lone-pair impact of Bi 6s states, leading to the special optical properties and excellent photocatalytic activities.

  6. Electronic Structures of Asymmetrically Substituted Phthalocyanines and Their Second Non-linear Optical Properties

    Institute of Scientific and Technical Information of China (English)

    张天莉; 严继民

    2001-01-01

    Quantum-chemical AM1 calculations were performed to study the geometries,the electronic structures and the second nonlinear optical properties of phthalocyanine and some asymmetrically substituted phthalocyanines,which include tert-butyl,amino,dimethylamino,nitro,fluoro,chloro,bromo iodo and nitrile substituents. The relationships of the second nonlinear optical coefficients β with dipole moment μ, and β with the energy-gap differences of frontier orbitals ΔEDA were discussed. Two relationships are regular and all ΔEDA-μ show very good linear relationship.

  7. Microstructure/Property Relationships for Carbon Fiber Reinforced Aluminum Alloys.

    Science.gov (United States)

    1985-07-25

    hypodermic syringe and blunted needle . After mounting the fiber, the card containing the fiber is inserted into the test fixture (figure 2). The edges... theory suggesting that this may not necessarily be the case [211. They showed that a weak interface may, 14 in fact, lead to improved composite properties...agree, at least in principle , with Ochai and Murakami’s theory and composites produced from Cornie’s fibers proved to be quite strong longitudinally

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

    Science.gov (United States)

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

    2010-06-01

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

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

    Science.gov (United States)

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

    2003-01-01

    This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.

  10. Metal borohydrides and derivatives - synthesis, structure and properties

    DEFF Research Database (Denmark)

    Paskevicius, Mark; Jepsen, Lars Haahr; Schouwink, Pascal

    2017-01-01

    review new synthetic strategies along with structural, physical and chemical properties for metal borohydrides, revealing a number of new trends correlating composition, structure, bonding and thermal properties. These new trends provide general knowledge and may contribute to the design and discovery...

  11. Relationships between supercontraction and mechanical properties of spider silk

    Science.gov (United States)

    Liu, Yi; Shao, Zhengzhong; Vollrath, Fritz

    2005-12-01

    Typical spider dragline silk tends to outperform other natural fibres and most man-made filaments. However, even small changes in spinning conditions can have large effects on the mechanical properties of a silk fibre as well as on its water uptake. Absorbed water leads to significant shrinkage in an unrestrained dragline fibre and reversibly converts the material into a rubber. This process is known as supercontraction and may be a functional adaptation for the silk's role in the spider's web. Supercontraction is thought to be controlled by specific motifs in the silk proteins and to be induced by the entropy-driven recoiling of molecular chains. In analogy, in man-made fibres thermal shrinkage induces changes in mechanical properties attributable to the entropy-driven disorientation of `unfrozen' molecular chains (as in polyethylene terephthalate) or the `broken' intermolecular hydrogen bonds (as in nylons). Here we show for Nephila major-ampullate silk how in a biological fibre the spinning conditions affect the interplay between shrinkage and mechanical characteristics. This interaction reveals design principles linking the exceptional properties of silk to its molecular orientation.

  12. Relation between photochromic properties and molecular structures in salicylideneaniline crystals.

    Science.gov (United States)

    Johmoto, Kohei; Ishida, Takashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

    2012-06-01

    The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

  13. RaptorX-Property: a web server for protein structure property prediction

    OpenAIRE

    Wang, Sheng; Li, Wei; Liu, Shiwang; Xu, Jinbo

    2016-01-01

    RaptorX Property (http://raptorx2.uchicago.edu/StructurePropertyPred/predict/) is a web server predicting structure property of a protein sequence without using any templates. It outperforms other servers, especially for proteins without close homologs in PDB or with very sparse sequence profile (i.e. carries little evolutionary information). This server employs a powerful in-house deep learning model DeepCNF (Deep Convolutional Neural Fields) to predict secondary structure (SS), solvent acce...

  14. The Attitudes to Chocolate Questionnaire: psychometric properties and relationship to dimensions of eating.

    Science.gov (United States)

    Müller, Jochen; Dettmer, Dorothee; Macht, Michael

    2008-01-01

    The aim of the present study was to evaluate the psychometric properties of the Attitudes to Chocolate Questionnaire (ACQ). We analyzed the factor structure of the ACQ by conducting exploratory and confirmatory factor analyses in a sample of healthy adults and a sample of dietician students. Further, the relationship between the resulting ACQ factors and dimensions of eating behavior, personality, emotionality, and tests of the pleasantness, sweetness, and intensity of sugar and chocolate was examined. The results yielded a clear two-factor structure of the ACQ: The first factor (guilt) was composed of items concerning negative consequences of chocolate eating including the feeling of guilt. The second factor (craving) comprised items related to craving and emotional chocolate eating. Guilt correlated significantly with "emotional eating", "restrained eating", and with neuroticism. Craving correlated significantly with "emotional eating" and "external eating", with neuroticism, and with the "difficulty identifying feelings" facet of the Toronto Alexithymia Scale; further, it correlated highly with the average reported chocolate consumption and with the ratings of the intensity of taste of sugar. In conclusion, results support the validity of the German version of the ACQ and showed a stable factor structure and a good internal consistency.

  15. Sequence-structure relationship study in all-α transmembrane proteins using an unsupervised learning approach.

    Science.gov (United States)

    Esque, Jérémy; Urbain, Aurélie; Etchebest, Catherine; de Brevern, Alexandre G

    2015-11-01

    Transmembrane proteins (TMPs) are major drug targets, but the knowledge of their precise topology structure remains highly limited compared with globular proteins. In spite of the difficulties in obtaining their structures, an important effort has been made these last years to increase their number from an experimental and computational point of view. In view of this emerging challenge, the development of computational methods to extract knowledge from these data is crucial for the better understanding of their functions and in improving the quality of structural models. Here, we revisit an efficient unsupervised learning procedure, called Hybrid Protein Model (HPM), which is applied to the analysis of transmembrane proteins belonging to the all-α structural class. HPM method is an original classification procedure that efficiently combines sequence and structure learning. The procedure was initially applied to the analysis of globular proteins. In the present case, HPM classifies a set of overlapping protein fragments, extracted from a non-redundant databank of TMP 3D structure. After fine-tuning of the learning parameters, the optimal classification results in 65 clusters. They represent at best similar relationships between sequence and local structure properties of TMPs. Interestingly, HPM distinguishes among the resulting clusters two helical regions with distinct hydrophobic patterns. This underlines the complexity of the topology of these proteins. The HPM classification enlightens unusual relationship between amino acids in TMP fragments, which can be useful to elaborate new amino acids substitution matrices. Finally, two challenging applications are described: the first one aims at annotating protein functions (channel or not), the second one intends to assess the quality of the structures (X-ray or models) via a new scoring function deduced from the HPM classification.

  16. Relationship of geological and geothermal field properties: Midcontinent area, USA, an example

    Science.gov (United States)

    Forster, A.; Merriam, D.F.; Brower, J.C.

    1993-01-01

    Quantitative approaches to data analysis in the last decade have become important in basin modeling and mineral-resource estimation. 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 reasonably simple to compare spatial data of the same type but more difficult if different properties are involved. Statistical techniques, such as cluster analysis or principal components analysis, or some algebraic approaches 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 data were copared. As expected, the structural maps are highly related because all had undergone about the same deformation with differing degrees of intensity. The temperature gradients derived (1) from shallow borehole logging measurements under equilibrium conditions with the surrounding rock, and (2) from non-equilibrium bottom-hole temperatures (BHT) from deeper depths are mainly independent of each other. This was expected and confirmed also 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 a 2-point (BHT and surface temperature) straightline calculation of a mean temperature gradient gives different information about the geothermal regime than using gradients from temperatures logged under equilibrium conditions. Nevertheless, it is useful to determine to what a degree the larger dataset of nonequilibrium temperatures could reflect quantitative relationships to geologic conditions. Comparing all maps of geothermal information vs. the structural and the sediment thickness maps, it was determined that all correlations are moderately

  17. 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

  18. The relationship between acoustic radiation modes and structural modes and its applications

    Institute of Scientific and Technical Information of China (English)

    LI Shuang; CHEN Ke'an

    2007-01-01

    Both acoustic radiation modes and structural modes play an important role in the field of structure-borne sound, however, little work has been done for inherent relations between these two kinds of modes. This paper is focused on the relationship between the radiation modes and structural modes and its physical mechanisms. First, a governing equation for relating the radiation mode and structural mode is given based on the characteristics of the modes. Then, using the symmetric or anti-symmetric properties of two kinds of modes, the corresponding relations are presented. And then, numerical examples are given to verify the theoretical investigations, and it has been shown that, for a simply supported rectangular panel vibrating at low frequencies, the first radiation mode is dominant corresponding to (odd, odd)structural modes; the following radiation modes are respectively dominant corresponding to (even, odd), (odd, even), and (even, even) structural modes. Finally, such relations are applied to active acoustic structural control and provide a direct help for the design of active control strategy and arrangement of the secondary forces.

  19. 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.

  20. Structure-Property Relationships in Polycyanurate / Graphene Networks

    Science.gov (United States)

    2015-12-12

    Motivation • Sequentially Prepared Graphene Types • Polycyanurate / GO Composite Preparation • Composite Morphology • Composite Mechanical and Physical...Composites Sample Kq (KIC) (psi·in1/2) LECy 988 ± 311 1 wt% GO 1353 ± 75 1 wt% TRGO 1270 ± 208 • The extent of reinforcement does appear to correlate with

  1. 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.

  2. Structure property relationships for the nonlinear optical response of fullerenes

    Science.gov (United States)

    Rustagi, Kailash C.; Ramaniah, Lavanya M.; Nair, Selvakumar V.

    1994-11-01

    We present a phenomenological theory of nonlinear optical response of fullerenes. An empirical tight-binding model is used in conjunction with a classical electromagnetic picture for the screening. Since in bulk media such a picture of screening corresponds to the self- consistent field approach, the only additional approximation involved in our approach is the neglect of nonlocality. We obtain reliable estimates for the linear and nonlinear susceptibilities of C60, C70, C76 and other pure carbon fullerenes and also substituted fullerenes. The relatively large values of (beta) that we obtain for C76 and substituted fullerenes appear promising for the development of fullerene-based nonlinear optical materials. Our phenomenological picture of screening provides a good understanding of the linear absorption spectra of higher fullerenes and predicts that a comparison of the one-photon and multi-photon spectra will provide an insight into screening effects in these systems.

  3. Chromatographic Retention Times of Polychlorinated Biphenyls: from Structural Information to Property Characterization

    Directory of Open Access Journals (Sweden)

    Mircea V. Diudea

    2006-11-01

    Full Text Available The paper presents a unitary approach of the use of a Molecular DescriptorsFamily in structure-property/activity relationships, particularly in modelling thechromatographic retention times of polychlorinated biphenyls. Starting from molecularstructure, viewed as a graph, and considering the bonds and bond types, atom types andoften the 3D geometry of the molecule, a huge family of molecular descriptors called MDFwas calculated. A preliminary selection of MDF members was done by simple linearregression (LR against the measured property. The best fitted MDF subset is thensubmitted to multivariate linear regression (MLR analysis in order to find the best pairs ofMDF members that produce a reliable QSPR (Quantitative Structure-PropertyRelationship model. The predictive capability was finally tested by randomly splitting ofdata into training and test sets. The best obtained models are presented and the results arediscussed.

  4. 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.

  5. Using structural equation modeling to investigate relationships among ecological variables

    Science.gov (United States)

    Malaeb, Z.A.; Kevin, Summers J.; Pugesek, B.H.

    2000-01-01

    Structural equation modeling is an advanced multivariate statistical process with which a researcher can construct theoretical concepts, test their measurement reliability, hypothesize and test a theory about their relationships, take into account measurement errors, and consider both direct and indirect effects of variables on one another. Latent variables are theoretical concepts that unite phenomena under a single term, e.g., ecosystem health, environmental condition, and pollution (Bollen, 1989). Latent variables are not measured directly but can be expressed in terms of one or more directly measurable variables called indicators. For some researchers, defining, constructing, and examining the validity of latent variables may be the end task of itself. For others, testing hypothesized relationships of latent variables may be of interest. We analyzed the correlation matrix of eleven environmental variables from the U.S. Environmental Protection Agency's (USEPA) Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) using methods of structural equation modeling. We hypothesized and tested a conceptual model to characterize the interdependencies between four latent variables-sediment contamination, natural variability, biodiversity, and growth potential. In particular, we were interested in measuring the direct, indirect, and total effects of sediment contamination and natural variability on biodiversity and growth potential. The model fit the data well and accounted for 81% of the variability in biodiversity and 69% of the variability in growth potential. It revealed a positive total effect of natural variability on growth potential that otherwise would have been judged negative had we not considered indirect effects. That is, natural variability had a negative direct effect on growth potential of magnitude -0.3251 and a positive indirect effect mediated through biodiversity of magnitude 0.4509, yielding a net positive total effect of 0

  6. 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. For example, with an elastic rod having cubical elastic nonlinearities, it seems possible to control...... the effective propagation speed of long waves by varying the amplitude of a superimposed high-frequency standing wave. It should be possible to change most properties related to structural stiffness, energy dissipation, and equilibrium states this way, by exploiting the general effects of stiffening, biasing...

  7. 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.

  8. Structure-response relationship in electrospray ionization-mass spectrometry of sartans by artificial neural networks.

    Science.gov (United States)

    Golubović, Jelena; Birkemeyer, Claudia; Protić, Ana; Otašević, Biljana; Zečević, Mira

    2016-03-18

    Quantitative structure-property relationship (QSPR) methods are based on the hypothesis that changes in the molecular structure are reflected in changes in the observed property of the molecule. Artificial neural network is a technique of data analysis, which sets out to emulate the human brain's way of working. For the first time a quantitative structure-response relationship in electrospray ionization-mass spectrometry (ESI-MS) by means of artificial neural networks (ANN) on the group of angiotensin II receptor antagonists--sartans has been established. The investigated descriptors correspond to different properties of the analytes: polarity (logP), ionizability (pKa), surface area (solvent excluded volume) and number of proton acceptors. The influence of the instrumental parameters: methanol content in mobile phase, mobile phase pH and flow rate was also examined. Best performance showed a multilayer perceptron network with the architecture 6-3-3-1, trained with backpropagation algorithm. It showed high prediction ability on the previously unseen (test) data set with a coefficient of determination of 0.994. High prediction ability of the model would enable prediction of ESI-MS responsiveness under different conditions. This is particularly important in the method development phase. Also, prediction of responsiveness can be important in case of gradient-elution LC-MS and LC-MS/MS methods in which instrumental conditions are varied during time. Polarity, chargeability and surface area all appeared to be crucial for electrospray ionization whereby signal intensity appeared to be the result of a simultaneous influence of the molecular descriptors and their interactions. Percentage of organic phase in the mobile phase showed a positive, while flow rate showed a negative impact on signal intensity.

  9. Structure and mechanical properties of high-temperature titanium alloys after rapid heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Ivasishin, O.M. (Inst. for Metal Physics, Kiev (Ukraine)); Luetjering, G. (Technical Univ. Hamburg-Harburg, Hamburg (Germany))

    1993-08-30

    In this study a new approach to optimizing the mechanical properties of high-temperature titanium alloys was developed. It is based on using rapid heating of equiaxed structures into the [beta]-field to achieve a fine [beta] grain size (less than or equal to 100 [mu]m), transforming on subsequent cooling into a fully lamellar structure. This fine [beta] grain size is an order of magnitude smaller than the grain sizes achieved by conventional furnace [beta]-treatment. Structures and mechanical properties (tensile, fatigue and creep) of high temperature alloys after rapid and conventional furnace heat treatments were compared. The results are discussed in terms of structure-property relationships. (orig.)

  10. Structure and Properties of Energetic Materials

    Science.gov (United States)

    1992-12-02

    7.76 9.11 30 Gurney energy (MJ/kg) 1.1 1.6 30 Heat of detonation (MJ/kg) -5.02 -6.78 30 In Table 2 we compare the properties of TATB and...velocity of HMX is some 17% greater than that of TATB, the Gurney energy 45% greater, and the heat of detonation 35% greater One reason that TATB...MJ/kg) 1.1 1.6 30 Heat of detonation (MJ/kg) -5.02 -6.78 30 In Table 2 we compare the properties of TATB and cyclotetramethylenetetranitramine (HMX

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

    KAUST Repository

    Ma, Zaifei

    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. © 2014 The Royal Society of Chemistry.

  12. 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.

  13. 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.

  14. 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 (μ) as well as linear solvation energy terms, molecular volume (Vi) and dipolar-polarization (π) 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.

  15. 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

  16. Electronic Properties of low dimensional structures

    CERN Document Server

    Bendounan, Azzedine

    2010-01-01

    Exotic phenomena about the behavior of electrons inside the solid were a long time ago predicted by the quantum mechanic physics and are only recently experimentally observed, in particular for systems of extremely reduced dimensions. Here, I report on recent experimental observation of fundamental effect concerning the dispersion properties of the surface state influenced by the presence of surface reconstruction.

  17. The Relationship between Secondary Structure and Biodegradation Behavior of Silk Fibroin Scaffolds

    Directory of Open Access Journals (Sweden)

    Yongpei Hu

    2012-01-01

    Full Text Available Silk fibroin has a unique and useful combination of properties, including good biocompatibility and excellent mechanical performance. These features provided early clues to the utility of regenerated silk fibroin as a scaffold/matrix for tissue engineering. The silk fibroin scaffolds used for tissue engineering should degrade at a rate that matches the tissue growth rate. The relationship between secondary structure and biodegradation behavior of silk fibroin scaffolds was investigated in this study. Scaffolds with different secondary structure were prepared by controlling the freezing temperature and by treatment with carbodiimide or ethanol. The quantitative proportions of each secondary structure were obtained by Fourier transform infrared spectroscopy (FTIR, and each sample was then degraded in vitro with collagenase IA for 18 days. The results show that a high content of β-sheet structure leads to a low degradation rate. The random coil region in the silk fibroin material is degraded, whereas the crystal region remains stable and the amount of β-sheet structure increases during incubation. The results demonstrate that it is possible to control the degradation rate of a silk fibroin scaffold by controlling the content of β-sheet structure.

  18. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    The composition of glass can be varied continuously within their glass-forming regions. This compositional flexibility makes it possible to tailor the properties of a glass for a variety of specific uses. In the industry such tailoring is done on a trial-and-error basis with only the intuition...... also increases such properties. Yet, these rules are not strictly followed even for the simplest binary oxide glasses, such as alkali silicates, borates and phosphates. In this thesis it is argued that the missing link between composition and properties is the glass structure. Structural models...... capable of ab initio prediction of the oxide glass properties from composition....

  19. Electric and magnetic properties computed for valence bond structures: is there a link between pauling resonance energy and ring current?

    Science.gov (United States)

    Havenith, Remco W A

    2006-04-28

    To establish the link between the aromaticity descriptors based on the Pauling resonance energy and the molecular properties, the electric (polarizability) and magnetic (magnetizability) field response properties have been calculated using the valence bond approach for various molecules and their individual Kekulé resonance structures. The results show that there is no direct relationship between the Pauling resonance energy and the properties; the response properties are weighted averages of the properties of the individual structures. According to the aromaticity criteria based on molecular properties, one-structure benzene would be aromatic; thus, concerning molecular properties, spin-coupled bonds do not behave like localized bonds in Lewis structures, with which they are usually associated.

  20. 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 ...

  1. Structure sensitive properties of KTP-type crystals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Adding various dopants during the growth of the parent KTiOPO4 (KTP) crystal has given rise to an extensive series of KTP-type crystals. The doped KTP or KTP-type crystals often have very subtle structural variations from pure KTP crystals. As a result of these structural changes the KTP-type crystals often exhibit different physical properties, which may be referred to as structure sensitive properties. It is possible to fine-tune the nonlinear optical properties of KTP crystals through doping. This results in a broad range of applications for KTP-type crystals.

  2. 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.

  3. Antiplasmodial Activity, Cytotoxicity and Structure-Activity Relationship Study of Cyclopeptide Alkaloids

    Directory of Open Access Journals (Sweden)

    Emmy Tuenter

    2017-02-01

    Full Text Available Cyclopeptide alkaloids are polyamidic, macrocyclic compounds, containing a 13-, 14-, or 15-membered ring. The ring system consists of a hydroxystyrylamine moiety, an amino acid, and a β-hydroxy amino acid; attached to the ring is a side chain, comprised of one or two more amino acid moieties. In vitro antiplasmodial activity was shown before for several compounds belonging to this class, and in this paper the antiplasmodial and cytotoxic activities of ten more cyclopeptide alkaloids are reported. Combining these results and the IC50 values that were reported by our group previously, a library consisting of 19 cyclopeptide alkaloids was created. A qualitative SAR (structure-activity relationship study indicated that a 13-membered macrocyclic ring is preferable over a 14-membered one. Furthermore, the presence of a β-hydroxy proline moiety could correlate with higher antiplasmodial activity, and methoxylation (or, to a lesser extent, hydroxylation of the styrylamine moiety could be important for displaying antiplasmodial activity. In addition, QSAR (quantitative structure-activity relationship models were developed, using PLS (partial least squares regression and MLR (multiple linear regression. On the one hand, these models allow for the indication of the most important descriptors (molecular properties responsible for the antiplasmodial activity. Additionally, predictions made for interesting structures did not contradict the expectations raised in the qualitative SAR study.

  4. Relationship between the microstructure and the mechanical and barrier properties of whey protein films.

    Science.gov (United States)

    Anker, M; Stading, M; Hermansson, A M

    2000-09-01

    This work was focused on the relationship between the microstructure and the mechanical and barrier properties of whey protein isolate (WPI) films. Sorbitol (S) and glycerol (G) were used as plasticizers and the pH was varied between 7 and 9. The films were cast from heated aqueous solutions and dried in a climate room at 23 degrees C and 50% relative humidity for 16 h. The microstructure of the films was found to be dependent on the concentration, the plasticizers, and the pH. When the concentration increased, a more aggregated structure was formed, with a denser protein network and larger pores. This resulted in increased water vapor permeability (WVP) and decreased oxygen permeability (OP). When G was used as a plasticizer instead of S, the microstructure was different, and the moisture content and WVP approximately doubled. When the pH increased from 7 to 9, a denser protein structure was formed, the strain at break increased, and the OP decreased.

  5. Microstructure-property relationship in magnetoelectric bulk composites

    Energy Technology Data Exchange (ETDEWEB)

    Sheikh, Arif D.; Fawzi, Abdulsamee [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune 411 007, M.S. (India); Mathe, V.L., E-mail: vlmathe@physics.unipune.ernet.i [Novel Materials Research Laboratory, Department of Physics, University of Pune, Pune 411 007, M.S. (India)

    2011-03-15

    We present systematic studies that comprise phase connectivity and dielectric, multiferroic (MF) and magnetoelectric (ME) properties of (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4}+(1-x) Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.67}Ti{sub 0.33}O{sub 3} [where x=0.15, 0.30 and 0.45] ME composites prepared by conventional solid-state reaction method. Scanning electron microscopic images of the composites predict different types of connectivity schemes viz 3-0, 3-1 and 3-3. The phase transition temperature of PMN-PT is independent of Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} content. Room temperature P-E and M-H loops indicate the simultaneous existence of ferroelectric/magnetic ordering. In order to study the possibility of monitoring electrical ordering by means of a magnetic field, ME measurements were carried out. The composition-dependent phase connectivity was well co-related to formation of percolation path and inturn magnetoelectric output. - Research highlights: > Synthesis of (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4}+ (1-x) PMN-PT [where x=0.15, 0.30 and 0.45] ME composites. > Microstructure of the composites with x=0.15, 0.30 and 0.45, predicts different types of connectivity scheme viz 3-0, 3-1 and 3-3 respectively. > Dielectric behavior of the ME composites. > Room-temperature P-E and M-H loops indicate the existence of multiferroic ordering. > Co-relation of phase connectivity with magnetoelectric output.

  6. 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.

  7. The properties and structure of the carburizers

    Directory of Open Access Journals (Sweden)

    K. Janerka

    2010-01-01

    Full Text Available The results of examinations of the carburizers for foundry industry were presented in the article. The commonly used carburizers were selected for the experiments (anthracite, natural and synthetic graphite, petroleum coke of various grades, cupola coke and charcoal as well. The experiments consist of bulk and standard density, screen analysis (on the basis of it the equivalent diameter was calculated and the microstructure of the carburizers measurements. The chemical composition and basic properties of carburizers were described too.

  8. Electronic structures and physical properties of pure Cr, Mo and W

    Institute of Scientific and Technical Information of China (English)

    谢佑卿; 邓永平; 刘心笔

    2003-01-01

    Using the one atom theory, the electronic structures of pure Cr, Mo and W with bcc structure were determined respectively as: [Ar](3dc)3.32(3dn)2.26(4sc)0.25(4sf)0.17, [Kr](4dc)4.23(4dn)1.48(5sc)0.02(5sf)0.27 and [Xe](5dc)5.16(6sc)0.25(6sf)0.59.The electronic structures of these metals with hcp and fcc structures and liquid state were also studied. According to their electronic structures, the relationship between the electronic structure and crystalline structure was explained qualitatively and the relationship between the difference of mechanical properties and transport properties of pure Cr, Mo and W with bcc structure and their electronic structures was also explained qualitatively; the lattice constants, binding energy, potential curves, elasticities and the temperature dependence of the linear thermal expansion coefficient of bcc-Cr, bcc-Mo and bcc-W were calculated quantitatively.

  9. Structure-activity relationships in carbohydrates revealed by their hydration.

    Science.gov (United States)

    Maugeri, Laura; Busch, Sebastian; McLain, Sylvia E; Pardo, Luis Carlos; Bruni, Fabio; Ricci, Maria Antonietta

    2016-12-21

    One of the more intriguing aspects of carbohydrate chemistry is that despite having very similar molecular structures, sugars have very different properties. For instance, there is a sensible difference in sweet taste between glucose and trehalose, even though trehalose is a disaccharide that comprised two glucose units, suggesting a different ability of these two carbohydrates to bind to sweet receptors. Here we have looked at the hydration of specific sites and at the three-dimensional configuration of water molecules around three carbohydrates (glucose, cellobiose, and trehalose), combining neutron diffraction data with computer modelling. Results indicate that identical chemical groups can have radically different hydration patterns depending on their location on a given molecule. These differences can be linked with the specific activity of glucose, cellobiose, and trehalose as a sweet substance, as building block of cellulose fiber, and as a bioprotective agent, respectively. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editors: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

  10. STRUCTURAL DECOMPOSITION AND ITS PROPERTIES OF LINEAR MULTIVARIABLE SINGULAR SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    Minghua HE; Ben M. CHEN; Zongli LIN

    2007-01-01

    We present in this paper a structural decomposition for linear multivariable singular systems.Such a decomposition has a distinct feature of capturing and displaying all the structural properties,such as the finite and infinite zero structures, invertibility structures, and redundant dynamics of the given system. As its counterpart for non-singular systems, we believe that the technique is a powerful tool in solving control problems for singular systems.

  11. New membrane structures with proton conducting properties

    DEFF Research Database (Denmark)

    Nørgaard, Casper Frydendal

    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...... [1, 2, 3]. Improved fuel cell performance from incorporation of hygroscopic oxides or solid proton conductors (e.g. zirconium phosphates) has been reported. The poster exhibits upcoming work in the field of composite electrolyte membranes at the University of Southern Denmark, combining radiation...

  12. Detonation-synthesis nanodiamonds: synthesis, structure, properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Dolmatov, Valerii Yu [Federal State Unitary Enterprise Special Design-Technology Bureau (FSUE SDTB) ' ' Tekhnolog' ' at the St Petersburg State Institute of Technology (Technical University) (Russian Federation)

    2007-04-30

    The review outlines the theoretical foundations and industrial implementations of modern detonation synthesis of nanodiamonds and chemical purification of the nanodiamonds thus obtained. The structure, key properties and promising fields of application of detonation-synthesis nanodiamonds are considered.

  13. Stress-strain relationship with soil structural parameters of collapse loess

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Through the tri-axial shearing tests of unsaturated intact loess and based on the concept of comprehensive soil structural potential,this paper reveals the changing laws of soil structural property under the triaxial stress conditions and establishes a mathematical expression equation of structural parameters,whereby reflecting the effects of unsaturated loess water content,stress and strain states,which is introduced into the shearing stress and shearing strain relation to obtain the structural stress-strain relation.The tests reveal that the loess dilatancy is of shearing contraction and shearing expansion,whereby indicating that there is a good linear relation between the stress ratio and shearing expansion strain ratio.The larger consolidation confining pressure is,the larger the stress of shearing contraction and expansion critical point is;and the larger water content is,the smaller the strain ratio of shearing contraction and expansion critical point is.Finally,the constitutive model is established to reflect the variation in loess structure,stressstrain softening and hardening,and shearing contraction and shearing expansion features.Through the comparative analysis,the stress-strain curves described by the constitutive relationship are found to be in good conformity with test results,whereby testing the rationality of the model in this paper.

  14. Structure of associated sets to Midy's Property

    CERN Document Server

    Gilberto, García-Pulgarín; Miguel, Velásquez-Soto Juan

    2011-01-01

    Let $b$ be a positive integer greater than 1, $N$ a positive integer relatively prime to $b$, $ |b|_{N}$ the order of $b$ in the multiplicative group $% \\mathbb{U}_{N}$ of positive integers less than $N$ and relatively primes to $% N,$ and $x\\in\\mathbb{U}_{N}$. It is well known that when we write the fraction $\\frac{x}{N}$ in base $b$, it is periodic. Let $d,\\,k$ be positive integers with $% d\\geq2$ and such that $|b|_{N}=kd$ and $\\frac{x}{N}=0.% bar{a_{1}a_{2}...a_{|b|_{N}}}$ with the bar indicating the period and $a_{i}$ are digits in base $b$. We separate the period ${a_{1}a_{2}... a_{|b|_{N}}}$ in $d$ blocks of length $k$ and let $ A_{j}=[a_{(j-1)k+1}a_{(j-1)k+2}...a_{jk}]_{b} $ be the number represented in base $b$ by the $j-th$ block and $% S_{d}(x)=\\sum\\limits_{j=1}^{d}A_{j}$. If for all $x\\in\\mathbb{U}_{N}$, the sum $S_{d}(x)$ is a multiple of $b^{k}-1$ we say that $N$ has the Midy's property for $b$ and $d$. In this work we present some interesting properties of the set of positive integers $d$ such ...

  15. Fused aromatic thienopyrazines: structure, properties and function

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier mobility in thin film transistor devices and mobilities up to 0.2 cm2/Vs were achieved. The optoelectronic properties of these fused aromatic thienopyrazine polymers (Eg = 1.3 to 1.6 eV, HOMO = -4.9 to -5.2 V) were tuned by introduction of various fused aromatic rings within thienopyrazine. By balancing the fundamental properties of these polymers, both high charge carrier mobilities and moderate PCEs in solar cells were achieved. Further, effects of copolymerizing units are discussed. Low band gap semiconducting polymer (Eg ∼ 1 eV) with high field effect mobility (0.044 cm2/Vs) was obtained using cyclopentadithiophene as copolymerizing unit. Finally, a molecular design approach to enhance the absorption coefficients is discussed, which resulted in improved power conversion efficiency in bulk heterojunction solar cells. © 2010 The Royal Society of Chemistry.

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

    Directory of Open Access Journals (Sweden)

    En-Rong Yan

    Full Text Available 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.

  17. The structural and magnetic properties of holmium/scandium superlattices

    DEFF Research Database (Denmark)

    Bryn-Jacobsen, C.; Cowley, R.A.; McMorrow, D.F.;

    1997-01-01

    The properties of Ho/Sc superlattices grown by molecular beam epitaxy (MBE) have been investigated using X-ray and neutron diffraction techniques. Structural studies reveal the novel existence of more than one a lattice parameter. Examining the magnetic properties, it is found that the Ho 4f...

  18. [Structural properties and functional importance of metzincin metalloproteinases].

    Science.gov (United States)

    Balaban, N P; Rudakova, N L; Sharipova, M R

    2013-01-01

    Here wediscuss known properties of metzincin metalloproteinases, their structure, physiological roles in the cell and potential medical uses. We also present results describing a novel extracellular metzincin metalloproteinase from Bacillus pumilus with a unique combination of properties typical for both astacins and adamalysins.

  19. Organogels thermodynamics, structure, solvent role, and properties

    CERN Document Server

    Guenet, Jean-Michel

    2016-01-01

    This book provides a physics-oriented introduction to organogels with a comparison to polymer thermoreversible gels whenever relevant. The past decade has seen the development of a wide variety of newly-synthesized molecules that can spontaneously self-assemble or crystallize from their organic or aqueous solutions to produce fibrillar networks, namely organogels, with potential applications in organic electronics, light harvesting, bio-imaging, non-linear optics, and the like. This compact volume presents a detailed outlook of these novel molecular systems with special emphasis upon their thermodynamics, morphology, molecular structure, and rheology. The definition of these complex systems is also tackled, as well as the role of the solvent. The text features numerous temperature-phase diagrams for a variety of organogels as well as illustrations of their structures at the microscopic, mesoscopic and macroscopic level. A review of some potential applications is provided including hybrid functional materials ...

  20. Thermal structural properties of calcium tungstate

    Energy Technology Data Exchange (ETDEWEB)

    Senyshyn, Anatoliy; Hoelzel, Markus [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; Technische Univ. Muenchen, Garching (Germany). Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II; Hansen, Thomas [Institute Laue-Langevin, Grenoble (France); Vasylechko, Leonid [Lviv Polytechnic National Univ. (Ukraine). Semiconductor Electronics Dept.; Mikhailik, Vitaliy [Diamond Light Source, Harwell Science and Innovation Campus, Didcot (United Kingdom); Oxford Univ. (United Kingdom). Dept. of Physics; Kraus, Hans [Oxford Univ. (United Kingdom). Dept. of Physics; Ehrenberg, Helmut [Technische Univ. Darmstadt (Germany). Inst. for Materials Science; IFW Dresden (Germany)

    2011-04-15

    The results of in-situ temperature-resolved powder diffraction studies of CaWO{sub 4} scheelite using both synchrotron radiation and neutron scattering are reported. The studies performed over a broad temperature range of 5-1773 K confirm the scheelite type of structure for calcium tungstate over the whole temperature range. The anisotropy of thermal expansion in calcium tungstate as well as the rigidity of WO{sub 4} complexes have been analysed in terms of bond distances, interatomic angles and anisotropic displacement parameters. The WO{sub 4}{sup 2-} complex anions showed a remarkable robustness in the whole studied temperature range, thus pointing out that the layered structure formed by two-dimensional CsCl-type arrangements of Ca cations and WO{sub 4} complexes is the primary reason for the anisotropy of thermal expansion in calcium tungstate. (orig.)

  1. Structure and properties of layered inorganic materials

    Institute of Scientific and Technical Information of China (English)

    Xue Duan

    2010-01-01

    @@ Inorganic layered materials are a class of advanced functional materials that have attracted considerable attention by virtue of their practical applications in a wide variety of fields. Sys-tematic studies of structure, design, synthesis, and fabrication processing may extend the range of practical utility of inor-ganic layered functional materials, in areas such as food industry,chemical industry, energy engineering, environmental engineer-ing, drug and gene delivery, electronics technology, and materials protection.

  2. Theoretical study on the band structure and optical properties of 4H-SiC

    Institute of Scientific and Technical Information of China (English)

    Xu Peng-Shou; Xie Chang-Kun; Pan Hai-Bin; Xu Fa-Qiang

    2004-01-01

    We have studied the band structure and optical properties of 4H-SiC by using a full potential linearized augmented plane waves (FPLAPW) method. The density of states (DOS) and band structure are presented. The imaginary part of the dielectric function has been obtained directly from the band structure calculation. With band gap correction, the real part of the dielectric function has been derived from the imaginary part by the Kramers-Kronig (KK) dispersion relationship. The values of reflectivity for normal incidence as a function of photon energy have also been calculated.We found the theoretical results are in good agreement with the experimental data.

  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. Structural Properties and Phonon dispertion of NACl

    Directory of Open Access Journals (Sweden)

    R. Khoda-Bakhsh

    2001-06-01

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

  5. Structure and Properties of Liquid Crystals

    CERN Document Server

    Blinov, Lev M

    2011-01-01

    This book by Lev M. Blinov is ideal to guide researchers from their very first encounter with liquid crystals to the level where they can perform independent experiments on liquid crystals with a thorough understanding of their behaviour also in relation to the theoretical framework. Liquid crystals can be found everywhere around us. They are used in virtually every display device, whether it is for domestic appliances of for specialized technological instruments. Their finely tunable optical properties make them suitable also for thermo-sensing and laser technologies. There are many monographs written by prominent scholars on the subject of liquid crystals. The majority of them presents the subject in great depth, sometimes focusing on a particular research aspect, and in general they require a significant level of prior knowledge. In contrast, this books aims at an audience of advanced undergraduate and graduate students in physics, chemistry and materials science. The book consists of three parts: the firs...

  6. Thermoelectric Properties of Silicon Microchannel Plates Structures

    Energy Technology Data Exchange (ETDEWEB)

    Ci, P L; Shi, J; Wang, F; Sun, L; Xu, S H; Yang, P X; Wang, L W [Laboratory of Polar Materials and Devices, Ministry of Education, and Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Chu, Paul K, E-mail: lwwang@ee.ecnu.edu.cn [Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2011-02-01

    We have fabricated silicon microchannel plates (MCPs) by photo-assisted electrochemical etching (PAECE) and determined the thermoelectric properties by measuring the Seebeck coefficient of the samples. The samples are composed of regular arrayed lattices with a width of about 5 {mu}m and spacing of about 1 {mu}m. The Seebeck coefficient along the edge of the lattice is 466 {mu}V/K. The silicon MCPs are potential materials for power generation and refrigeration. After oxidation from 30 minutes to 70 minutes and removing the silicon dioxide layer by buffered hydrofluoric acid, the samples show an improved coefficient as high as 1019 {mu}V/K after repeating oxidation and etching 5 times. Our results show that the Seebeck coefficient increases when the wall of the silicon MCPs is thinned.

  7. Modeling structural acoustic properties of loudspeaker cabinets

    DEFF Research Database (Denmark)

    Luan, Yu

    In this dissertation, a theoretical/numerical methodology is presented for coarse and fast predictions of cabinet vibrations. The study is focused on vibrations of rib-stiffened panels by improving a smearing technique and employing it into finite element modeling. The computationally efficient...... in the calculation of bending stiffness in this dissertation. The improved smearing technique results in good accuracy for predicted natural frequencies and forced vibrations of flat stiffened plates. Another improvement concerns the orientation of the stiffeners. The original smearing technique presupposes...... the vibrational properties and associated sound radiation of models including stiffened panels. Overall, the developed technique is found to be a good method for fast estimations of cabinet vibrations....

  8. Direct-writing construction of layered meshes from nanoparticles-vaseline composite inks: rheological properties and structures

    Science.gov (United States)

    Cai, Kunpeng; Sun, Jingbo; Li, Qi; Wang, Rui; Li, Bo; Zhou, Ji

    2011-02-01

    Direct-writing is superior in the construction of arbitrarily designed three-dimensional (3D) structures. In this work, we develop a series of organic inks doped with nanoparticles to fabricate 3D meshes of interpenetrating rods. The effects of nanoparticle addition on the rheological properties of organic inks were analyzed. The results revealed intelligible relationship between the ink's formability and rheological properties, which could be beneficial to the construction of 3D structures from organic inks by direct writing.

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

    Science.gov (United States)

    Hallinger, Philip; Richardson, Don

    1988-01-01

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

  10. Surface structure and electronic properties of materials

    Science.gov (United States)

    Siekhaus, W. J.; Somorjai, G. A.

    1975-01-01

    A surface potential model is developed to explain dopant effects on chemical vapor deposition. Auger analysis of the interaction between allotropic forms of carbon and silicon films has shown Si-C formation for all forms by glassy carbon. LEED intensity measurements have been used to determine the mean square displacement of surface atoms of silicon single crystals, and electron loss spectroscopy has shown the effect of structure and impurities on surface states located within the band gap. A thin film of Al has been used to enhance film crystallinity at low temperature.

  11. Structural and Optical Properties and Emerging Applications of Metal Nanomaterials

    Institute of Scientific and Technical Information of China (English)

    Tammy Y.Olson; Jin Z.Zhang

    2008-01-01

    Nanomaterials possess intriguing optical properties that depend sensitively on size, shape, and material content of the structures. Controlling such structural characteristics of the nanostructures allows the tailoring of their physical and chemical properties, e.9. optical, electronic, and catalytic, to achieve what is desired for specific applications of interest. This review will cover the development of various shapes for silver and gold nanomaterials with emphasis on their relation to optical properties. Examples of various modern synthetic methods and characterization techniques are highlighted. The influence of the metal nanomaterial's shape and optical absorption on surface enhanced Raman scattering (SERS) and a final note on new emerging applications of metal nanostructures are also discussed.

  12. Density Functional Theory and Electrochemical Studies: Structure-Efficiency Relationship on Corrosion Inhibition.

    Science.gov (United States)

    Camacho-Mendoza, Rosa L; Gutiérrez-Moreno, Evelin; Guzmán-Percástegui, Edmundo; Aquino-Torres, Eliazar; Cruz-Borbolla, Julián; Rodríguez-Ávila, José A; Alvarado-Rodríguez, José G; Olvera-Neria, Oscar; Thangarasu, Pandiyan; Medina-Franco, José L

    2015-11-23

    The relationship between structure and corrosion inhibition of a series of 30 imidazol, benzimidazol, and pyridine derivatives has been established through the investigation of quantum descriptors calculated with PBE/6-311++G**. A quantitative structure-property relationship model was obtained by examination of these descriptors using a genetic functional approximation method based on a multiple linear regression analysis. Our results indicate that the efficiency of corrosion inhibitors is strongly associated with aromaticity, electron donor ability, and molecular volume descriptors. In order to calibrate and validate the proposed model, we performed electrochemical impedance spectroscopy (EIS) studies on imidazole, 2-methylimidazole, benzimidazole, 2-chloromethylbenzimidazole, pyridine, and 2-aminopyridine compounds. The experimental values for efficiency of corrosion inhibition are in good agreement with the estimated values obtained by our model, thus confirming that our approach represents a promising and suitable tool to predict the inhibition of corrosion attributes of nitrogen containing heterocyclic compounds. The adsorption behavior of imidazole or benzimidazole heterocyclic molecules on the Fe(110) surface was also studied to elucidate the inhibition mechanism; the aromaticity played an important role in the adsorbate-surface complex.

  13. 基于氨基酸性质的EB病毒抗原MHC-I类分子限制性表位的定量构效关系建模%Quantitative structure-activity relationship modeling of MHC class-Ⅰrestrained antigenic epitope of Epstein-Barr virus based on the properties of amino acids

    Institute of Scientific and Technical Information of China (English)

    韩英子; 王远强; 胡勇; 纪永军; 路亚阔; 蓝君; 罗鸿; 林治华

    2013-01-01

    目的 建立EB病毒(EBBV)抗原表位的理论计算模型并用于其定量预测,为肿瘤免疫的多肽疫苗设计提供理论基础.方法 从表位数据库中收集33条EBV抗原表位,使用逐步回归(STR)方法筛选2个对平衡解离常数(KD)贡献较大的结构参数用于表位的结构表征,最后用多元线性回归(MLR)方法建立结构参数与KD的定量构效关系(QSAR)模型.结果 该模型具有较好的稳定性(R2=0.637,Q2=0.581)与预测能力(R2test=0.501).结论 此方法可确定表位中各个氨基酸的物理性质对于平衡解离常数的贡献,为表位设计与改造提供直接线索;STR和MLR相结合建模方法具有物化意义明确、易于解释及操作简便易行等优点.%Epstein-Barr virus (EBV) is highly associated with several neoplastic diseases. The development of vaccine based on the antigenic epitope is very important for immunotherapies of human cancers. It is necessary to construct theoretical model for quantitative prediction of epitope, because the identification and screen of epitope need long time and high cost through experiments. In this study, 33 epitopes from EBV had been collected from epitope database. Then, the properties with significant contribution for equilibrium dissociation constant (KD) were screened by the stepwise, which were used to characterize the epitopes. Finally, the quantitative structure-activity relationship model between structural variables and KD was constructed by multiple linear regressions (MLR). The QSAR model has good reliability (R2=0.637, Q2=0.581) and predictive ability (R2test=0.501), and can provide more clues for the design and modification of epitope. The QSAR model constructed by STR and MLR has some advantages, such as good reliability and predictive ability, definitive physiochemical meaning and easier operation, and it can guide the rational design and structural modification of epitope directly.

  14. 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

  15. Reducing Behavioural to Structural Properties of Programs with Procedures

    NARCIS (Netherlands)

    Gurov, D.; Huisman, M.; Jones, N.D.; Müller-Olm, M.

    2009-01-01

    There is an intimate link between program structure and behaviour. Exploiting this link to phrase program correctness problems in terms of the structural properties of a program graph rather than in terms of its unfoldings is a useful strategy for making analyses more tractable. This paper presents

  16. Structural properties of Cd–Co ferrites

    Indian Academy of Sciences (India)

    S P Dalawai; T J Shinde; A B Gadkari; P N Vasambekar

    2013-10-01

    Ferrite samples with composition, CdCo1−Fe2O4 ( = 0.80, 0.85, 0.90, 0.95 and 1.0), were prepared by standard ceramic method and characterized by XRD, IR and SEM techniques. X-ray analysis confirms the formation of single phase cubic spinel structure. Lattice constant and grain size of the samples increase with increase in cadmium content. Bond length (A–O) and ionic radii (A) on -sites increase, whereas bond length (B–O) and ionic radii (B) on -site decrease. The crystallite sites of the samples lie in the range of 29.1–42.8 nm. IR study shows two absorption bands around 400 cm-1 and 600 cm-1 corresponding to tetrahedral and octahedral sites, respectively.

  17. Analysis of waveguiding properties of VCSEL structures

    Energy Technology Data Exchange (ETDEWEB)

    Erteza, I.A. [Sandia National Labs., Albuquerque, NM (United States). Exploratory Systems Development Center

    1996-09-01

    In this paper, the authors explore the feasibility of using the distributed Bragg reflector, grown on the substrate for a VCSEL (Vertical Cavity Surface Emitting Laser), to provide waveguiding within the substrate. This waveguiding could serve as an interconnection among VCSELs in an array. Before determining the feasibility of waveguide interconnected VCSELs, two analysis methods are presented and evaluated for their applicability to this problem. The implementations in Mathematica of both these methods are included. Results of the analysis show that waveguiding in VCSEL structures is feasible. Some of the many possible uses of waveguide interconnected VCSELs are also briefly discussed. The tools and analysis presented in this report can be used to evaluate such system concepts and to do detailed design calculations.

  18. Ab initio calculation of structure and thermodynamic properties of Zintl aluminide SrAl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Zhi-Jian [Chongqing Key Laboratory of Micro/Nano Materials Engineering and Technology, Chongqing (China); Chongqing Univ. of Arts and Sciences (China). School of Electrical and Electronic Engineering; China Academy of Engineering Physics (CAEP), Mianyang, Sichuan (China). National Key Lab. of Shock Wave and Detonation Physics; Jia, Li-Jun [Chongqing Univ. of Arts and Sciences Library (China); Xia, Ji-Hong; Tang, Ke; Li, Zhao-Hong [Chongqing Univ. of Arts and Sciences (China). School of Electrical and Electronic Engineering; Sun, Xiao-Wei [Lanzhou Jiaotong Univ. (China). School of Mathematics and Physics; Chen, Qi-Feng [China Academy of Engineering Physics (CAEP), Mianyang, Sichuan (China). National Key Lab. of Shock Wave and Detonation Physics

    2015-07-01

    The structural and thermodynamic properties of the orthorhombic and cubic structure SrAl{sub 2} at pressure and temperature are investigated by using the ab initio plane-wave pseudopotential density functional theory method within the generalised gradient approximation (GGA). The calculated lattice parameters are in agreement with the available experimental data and other theoretical results. The phase transition predicted takes place at 0.5 GPa from the orthorhombic to the cubic structure at zero temperature. The thermodynamic properties of the zinc-blende structure SrAl{sub 2} are calculated by the quasi-harmonic Debye model. The pressure-volume relationship and the variations in the thermal expansion a are obtained systematically in the pressure and temperature ranges of 0-5 GPa and 0-500 K, respectively.

  19. Structure and function relationships of proteins based on polar profile: a review.

    Science.gov (United States)

    Polanco, Carlos; Buhse, Thomas; Uversky, Vladimir N

    2016-01-01

    Proteins in the post-genome era impose diverse research challenges, the main are the understanding of their structure-function mechanism, and the growing need for new pharmaceutical drugs, particularly antibiotics that help clinicians treat the ever- increasing number of Multidrug-Resistant Organisms (MDROs). Although, there is a wide range of mathematical-computational algorithms to satisfy the demand, among them the Quantitative Structure-Activity Relationship algorithms that have shown better performance using a characteristic training data of the property searched; their performance has stagnated regardless of the number of metrics they evaluate and their complexity. This article reviews the characteristics of these metrics, and the need to reconsider the mathematical structure that expresses them, directing their design to a more comprehensive algebraic structure. It also shows how the main function of a protein can be determined by measuring the polarity of its linear sequence, with a high level of accuracy, and how such exhaustive metric stands as a "fingerprint" that can be applied to scan the protein regions to obtain new pharmaceutical drugs, and thus to establish how the singularities led to the specialization of the protein groups known today.

  20. Effect of wet grinding on structural properties of ball clay

    Science.gov (United States)

    Purohit, A.; Hameed, A.; Chander, S.; Nehra, S. P.; Si