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Sample records for structure properties relationships

  1. Structure-Property Relationship of Thermoset Nanocomposites

    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 relationship between the structure and mechanical properties of nanocomposite systems. We characterized the nanocomposite systems experimentally using rheology, X-ray diffraction, Thermo-mechanical a...

  2. Structure Property Relationships of Carboxylic Acid Isosteres.

    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. PMID:26967507

  3. Structure-property relationships in bainitic steels

    Edmonds, D. V.; Cochrane, R. C.

    1990-06-01

    Bainitic microstructures can be produced in a variety of steels either as a result of a deliberate attempt to achieve a particular combination of strength and toughness or in response to welding during fabrication. In addition, such microstructures can offer advantages in terms of their resistance to creep or fatigue deformation or susceptibility to hydrogen embrittlement. The relationships among chemical composition, processing, microstructure, and the mechanical properties will be reviewed. Particular emphasis will be placed on recent advances in alloy design. These developments rely on an improved understanding of the mechanisms of bainitic transformation, and the relevance of recent research in this area to the design of new alloy systems will be discussed. Bainitic structures which arise during welding can have a significant and sometimes detrimental effect on the fracture toughness of the welded joint. The fracture toughness of bainitic microstructures in so-called “local brittle zones” in the heat-affected zone and in weld metals and the importance of controlling the bainitic morphology will be considered and the transformation mechanisms discussed. In summary, the aim of this review will be to indicate the prospects for improved microstructural control of structure-property relationships in steels containing a significant proportion of bainite.

  4. Structural Property Relationships in Conjugated Polymers

    Lynch, Patrick; O'Neill, Luke; Whelan, J; McNamara, Mary; Byrne, Hugh

    2005-01-01

    The synthesis of a series of PPV derivative polymers by the Wittig-Horner reaction is described. The structure of each polymer is varied and the effects of these variations on the optical properties is explored. The effects of alkyloxy side chains is observed between the PPV derivatives Poly(-p-phenylvinylene-co-2,5-bis-octyloxy phenylvinylene.) PPV-OPV and Poly (para-2,5-bis-(n-octyloxy)-phenylvinylene) POPV. The phenyl units of the soluble PPV derivative POPV are replaced by alternate napht...

  5. Structure-property relationships in polymer nanocomposites

    Matveeva, Anna

    2015-01-01

    Tese de Doutoramento em Ciência e Engenharia de Polímeros e Compósitos Carbon nanotubes/ carbon nanofibres (CNTs/CNFs) are considered to be among the most promising reinforcements for improving the mechanical properties of polymers while at the same time offering enhanced electrical and thermal conductivity. Because of their exceptionally high aspect ratio and high surface area in combination with a low density, already small volume fractions can potentially transfer their supe...

  6. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    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...

  7. Quantitative structure-retention (property) relationships in micellar electrokinetic chromatography.

    Poole, Salwa K; Poole, Colin F

    2008-02-22

    Quantitative structure-retention relationships (QSRRs) attempt to quantitatively understand the relationship between structure and retention and quantitative structure-property relationships (QSPRs) to explore the prediction of molecular properties from retention in chromatography. The application of these techniques to micellar electrokinetic chromatography (MEKC) and microemulsion electrokinetic chromatography (MEEKC) using surfactants, vesicles and liposomes is reviewed. A database of system constants for the solvation parameter model is assembled and critically discussed with respect to the interpretation of solvation properties of micellar pseudophases and their use to identify correlation models for the estimation of physicochemical and environmental properties from retention in MEKC and MEEKC. The use of structure-generated descriptors to model retention in MEKC is discussed and compared with experimental-based techniques. It is shown that the possibilities of exploiting the collection of tools that underpin QSRRs and QSPRs studies are only just starting to be realized in MEKC and more work is needed to convert from these possibilities to the realization of reliable and robust models for compounds of diverse structure. PMID:18207156

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

    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.

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

    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.

  10. Structure-Property Relationships of Solids in Pharmaceutical Processing

    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.

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

    Douglas J. Kleinc; Ovidiu Ivanciuc; Teodora Ivanciuc

    2006-01-01

    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-stru...

  12. Oxide Thermoelectric Materials: A Structure-Property Relationship

    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.

  13. Processing-structure-property relationships in oriented polymers

    Xia, Zhiyong

    The Processing-Structure-Property (P-S-P) relationships in oriented polymers have been studied in this dissertation. Controlled polymer orientation has been achieved through the equal channel angular extrusion (ECAE) process. The structure of the ECAE-oriented polymers have been investigated from all dimensional levels, i.e., from spherulitical scale (micrometer scale), lamellar scale (nanometer scale) to crystallographic scale (angstrom scale). The results indicate that the polymer spherulites are deformed into macrofibrils after one ECAE process. Within the macrofibrils, a "V-type" lamellar orientation has been formed to accommodate the overall straining of spherulites. The molecular chains in the crystalline lamellae are found to be tilted at a small angle with respect to the lamellar surface. Whereas, the molecular chains between the macrofibrils and crystalline lamellae are highly stretched. Property characterization indicates that ECAE-induced microstructure is responsible for the improved physical and mechanical properties. The improved physical and mechanical properties include high tensile modulus, higher impact fracture toughness and better scratch resistance. This research has also clarified several controversies in the research of semicrystalline polymers. First, this research gives an unambiguous account on the lamellar evolution during large-scale plastic deformation. The crystalline lamellae in the ECAE-oriented samples have been found to be evolved from the original crystalline lamellae. Secondly, the shifting of the primary relaxation peak in ECAE-oriented PET has been found to be due to the increase in molecular orientation. Thirdly, the transmission electron microscopy (TEM) indicates that in low crystallinity semicrystalline polymers, the larger value of the two characteristic lengths from small angle X-ray scattering (SAXS) correlation function analysis should be assigned to the crystalline lamellar thickness.

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

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

    2012-01-01

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

  15. Structure-property relationship and transport properties of structurally related silyl carbonate electrolytes

    Ten different substituted structurally related linear and cyclic carbonates were synthesized and investigated as electrolyte solvents for lithium-ion cells. Synthesis of the compounds, mainly silyl carbonates, was carried out via catalytic CO2 addition, nucleophilic substitution or hydrosilylation. Besides the ten synthesized compounds a binary mixture of a cyclic and linear silyl carbonate, propylene carbonate (PC), diethyl carbonate (DEC) and a binary mixture thereof were analyzed as a function of molar lithium ((bistrifluoromethyl) sulfonyl) imide LiTFSI ratio in order to develop a structure-property relationship. The extrapolation of the temperature-dependent ionic conductivities using Vogel-Tamman-Fulcher (VTF) equation revealed a solvent assisted ionic transport mechanism. The strength of interaction between the lithium-ion and the respective carbonates was investigated via 13C and 29Si NMR measurements by the change of the chemical shift upon LiTFSI addition. The results show that the interaction of the lithium ion with the cyclic carbonates is much stronger compared to the linear ones and varies among the different substituents. These findings were in good accordance with ionicities represented by the Walden product. The diffusivities of Li+ and TFSI− were determined via Pulsed Field Gradient STimulated Echo (PGSTE)-NMR. The hydrodynamic radii calculated thereof demonstrate the superior coordination ability of the cyclic carbonates as compared to linear structures. Furthermore, Haven ratios indicate rather different dissociation abilities of different carbonate solvents, depending on the structural fragment of the solvents

  16. Computational design and structure-property relationship studies on heptazines.

    Ghule, Vikas D; Sarangapani, Radhakrishnan; Jadhav, Pandurang M; Pandey, Raj Kishore

    2011-11-01

    This study aimed to design novel nitrogen-rich heptazine derivatives as high energy density materials (HEDM) by exploiting systematic structure-property relationships. Molecular structures with diverse energetic substituents at varying positions in the basic heptazine ring were designed. Density functional techniques were used for prediction of gas phase heat of formation by employing an isodesmic approach, while crystal density was assessed by packing calculations. The results reveal that nitro derivatives of heptazine possess a high heat of formation and further enhancement was achieved by the substitution of nitro heterocycles. The crystal packing density of the designed compounds varied from 1.8 to 2 g cm(-3), and hence, of all the designed molecules, nitro derivatives of heptazine exhibit better energetic performance characteristics in terms of detonation velocity and pressure. The calculated band gap of the designed molecules was analyzed to establish sensitivity correlations, and the results reveal that, in general, amino derivatives possess better insensitivity characteristics. The overall performance of the designed compounds was moderate, and such compounds may find potential applications in gas generators and smoke-free pyrotechnic fuels as they are rich in nitrogen content. PMID:21318236

  17. Relationship Between Structure and Viscoelastic Properties of Geosynthetics

    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.

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

    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

  19. Structure-Property Relationships of Flexible Polyurethane Foams

    Kaushiva, Bryan D.

    2002-01-01

    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....

  20. Relationship Between Structure and Viscoelastic Properties of Geosynthetics

    Loginova Irina; Artamonova Daria; Stolyarov Oleg

    2016-01-01

    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 carri...

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

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

    1994-01-01

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

  2. Structure-property relationships in discotic and elliptical mesogens

    Lavigueur, Christine

    2008-01-01

    Liquid crystals are a promising class of materials used in or proposed for a wide variety of applications, ranging from liquid crystal displays and light emitting diodes to photovoltaic devices and field effect transistors. Many molecular level structural features are known to influence the properties of liquid crystalline materials, but the outcome of this influence is often poorly understood. A strategy was developed for the formation of elliptical mesogens having a shape intermediate betwe...

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

    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.

  4. An Investigation of College Chemistry Students' Understanding of Structure-Property Relationships

    Cooper, Melanie M.; Corley, Leah M.; Underwood, Sonia M.

    2013-01-01

    The connection between the molecular-level structure of a substance and its macroscopic properties is a fundamental concept in chemistry. Students in college-level general and organic chemistry courses were interviewed to investigate how they used structure-property relationships to predict properties such as melting and boiling points. Although…

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

    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.

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

    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.

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

    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...

  8. Structure-property relationships in vegetable cell wall suspensions

    Sankaran, Ashwin Karthik

    2015-01-01

    Plant cell wall suspensions are widely present in daily food, such as soups, dressings and sauces. Cell walls of edible plants are made up of an intricate biopolymer network of mainly cellulose microfibrils, pectins, and hemicelluloses. Foodsnbsp;as soups, ketchup, etc are made up of cell wall components. Modern processing methods alter the chemical and physical nature of the cell wall which in turn affect the properties of the end product. There is a need in the industry to build a fundament...

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

    Terheggen, Logan; Cosby, Tyler; Sangoro, Joshua

    2015-03-01

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

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

    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.

  11. Structure-property relationships of PEMs using fluorous-ionic copolymers

    Tsang, Ming Wai Emily

    2011-01-01

    Proton exchange membranes (PEMs) are a key component in PEM fuel cells, serving as both a fuel separator and an electrolyte. The goal of this thesis work is to investigate structure-property relationships in PEMs. Specifically, the role of polymer microstructure on membrane morphology and physicochemical properties is examined. This is achieved by the design, synthesis and characterization of model polymers with controlled chain architectures and chemical composition, leading to membranes wit...

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

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

    Milan Šoškić; Ivana Porobić

    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...

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

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

    2016-02-01

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

  15. The role of structure-to-property-relationships in materials characterization

    Morgner, W.

    2000-07-01

    The paper deals with questions concerning the material characterization for steels in the field of engineering and metallurgy. Based on the structure-to-property-relationships, a procedure is proposed to strengthen the systematical development of methods for nondestructive characterization of materials. The state of the nondestructive characterization of metals is reviewed and applications are described in which adequate macroscopic physical properties are measured in order to characterize the materials state and properties nondestructively. The materials characterization of ball bearing steel and cast iron using multiparametrical approaches is discussed in detail.

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

    Han, M.K.

    2006-05-06

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

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

    Mi-Kyung Han

    2006-05-01

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

  18. Relationship between pore structure and mechanical properties of ordinary concrete under bending fatigue

    Zhang, B. [Univ. of Glasgow (United Kingdom). Dept. of Civil Engineering

    1998-05-01

    Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young`s modulus were also obtained and their relationships with these micro-meso properties were established. The intrinsic bending strength and intrinsic bending Young`s modulus were predicted from these relationships.

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

    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.

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

    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

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

    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

    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

    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.

  4. Composition-structure-property relationships of commercial polyurethane foams for mattresses

    Scarfato, P.; Di Maio, L.; D'Arienzo, L.; Rinaldi, S.; Incarnato, L.

    2015-12-01

    Three commercial flexible polyurethane foams used for mattress have been submitted to chemical-physical analyses, water vapor permeability and compression mechanical tests, in order to understand the relationships among their composition, structure, and some functional properties of interest for bedding applications. The results demonstrated that all the three foams have open cell morphology and similar cell structure, with average cell diameters ranging from 430 to 510 micron and wide cell size distribution. As a consequence, they also show comparable water vapor transport behavior. On the contrary, their mechanical response, in terms of hysteresis loss, surface firmness and resistance to bottoming out, was found strongly dependent on their chemical structure and molecular mobility, as inferred from infrared spectroscopy analysis.

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

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

    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.

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

    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.

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

    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

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

    Trišović Nemanja

    2011-10-01

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

  10. Linear and nonlinear quantitative structure-property relationship modelling of skin permeability.

    Khajeh, A; Modarress, H

    2014-01-01

    In this work, quantitative structure-property relationship (QSPR) models were developed to estimate skin permeability based on theoretically derived molecular descriptors and a diverse set of experimental data. The newly developed method combining modified particle swarm optimization (MPSO) and multiple linear regression (MLR) was used to select important descriptors and develop the linear model using a training set of 225 compounds. The adaptive neuro-fuzzy inference system (ANFIS) was used as an efficient nonlinear method to correlate the selected descriptors with experimental skin permeability data (log Kp). The linear and nonlinear models were assessed by internal and external validation. The obtained models with three descriptors show good predictive ability for the test set, with coefficients of determination for the MPSO-MLR and ANFIS models equal to 0.874 and 0.890, respectively. The QSPR study suggests that hydrophobicity (encoded as log P) is the most important factor in transdermal penetration. PMID:24090175

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

    Rendon, Stanley

    Thermotropic liquid crystalline polymers (TLCPs) offer considerable promise as high strength/lightweight engineering materials. Their excellent mechanical properties are derived from the spontaneous ordering of stiff polymer molecules in the melt state, which is ultimately translated into high molecular orientation in finished products. Understanding the effect of processing on molecular orientation, and specifically the role and mechanisms by which flow fields impact molecular orientation, is thus a prerequisite to rational design of processes that exploit and enhance the characteristics of TLCPs. The lack of fundamental knowledge to rationally anticipate structure development during processing of commercial main-chain TLCPs however, has significantly hindered the wide spread applicability of these materials. In light of the need for improved understanding of flow-orientation relationships in TLCPs, this thesis presents the first coordinated attempt to combine fundamental studies of orientation development in well-defined simple flows (simple shear) and complex processing flows (extrusion and injection molding) using in situ x-ray scattering methods, with structure and property investigations of injection molded plaques made from commercial TLCPs. The work described here addresses fundamental questions related to the shear-alignment behavior of several commercial (Vectra A950RTM, Vectra B950RTM) and pre-commercial (DHalphaMS) thermotropes. The use of well-established in situ x-ray scattering methods previously developed in the Burghardt group, has enabled us to probe the evolution of molecular orientation under the influence of various transient shear flow protocols some of which provide strong, indirect evidence of flow-tumbling behavior in Vectra copolyesters. In situ orientation studies in steady isothermal complex channel flows reveal that superposition of extensional gradients on the inhomogeneous shear of pressure-driven slit flows dramatically influences

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

    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.

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

    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

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

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

    1997-04-01

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

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

    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

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

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

    2015-11-01

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

  17. Multivariate characterisation and quantitative structure-property relationship modelling of nitroaromatic compounds

    A multivariate model to characterise nitroaromatics and related compounds based on molecular descriptors was calculated. Descriptors were collected from literature and through empirical, semi-empirical and density functional theory-based calculations. Principal components were used to describe the distribution of the compounds in a multidimensional space. Four components described 76% of the variation in the dataset. PC1 separated the compounds due to molecular weight, PC2 separated the different isomers, PC3 arranged the compounds according to different functional groups such as nitrobenzoic acids, nitrobenzenes, nitrotoluenes and nitroesters and PC4 differentiated the compounds containing chlorine from other compounds. Quantitative structure-property relationship models were calculated using partial least squares (PLS) projection to latent structures to predict gas chromatographic (GC) retention times and the distribution between the water phase and air using solid-phase microextraction (SPME). GC retention time was found to be dependent on the presence of polar amine groups, electronic descriptors including highest occupied molecular orbital, dipole moments and the melting point. The model of GC retention time was good, but the precision was not precise enough for practical use. An important environmental parameter was measured using SPME, the distribution between headspace (air) and the water phase. This parameter was mainly dependent on Henry's law constant, vapour pressure, log P, content of hydroxyl groups and atmospheric OH rate constant. The predictive capacity of the model substantially improved when recalculating a model using these five descriptors only

  18. Teaching Structure-Property Relationships: Investigating Molecular Structure and Boiling Point

    Murphy, Peter M.

    2007-01-01

    A concise, well-organized table of the boiling points of 392 organic compounds has facilitated inquiry-based instruction in multiple scientific principles. Many individual or group learning activities can be derived from the tabulated data of molecular structure and boiling point based on the instructor's education objectives and the students'…

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

    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

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

    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

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

    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

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

    Shin, Weon Gyu; Wang Jing [University of Minnesota, Department of Mechanical Engineering (United States); Mertler, Michael; Sachweh, Bernd [Fine Particle Technology and Particle Characterization, BASF SE (Germany); Fissan, Heinz [Institute of Energy and Environmental Technology e. V. (IUTA) (Germany); Pui, David Y. H., E-mail: dyhpui@umn.ed [The University of Minnesota, Department of Mechanical Engineering (United States)

    2009-01-15

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

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

    Goodarzi, Mohammad; Dos Santos Coelho, Leandro; 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. PMID:26890190

  4. The significance of grafting collagen on polycaprolactone composite scaffolds: processing-structure-functional property relationship.

    Kiran, S; Nune, K C; Misra, R D K

    2015-09-01

    The study concerns processing-structure-functional property relationship in organic-inorganic hybrid scaffolds based on grafted collagen for bone tissue engineering. Biodegradable polyester, polycaprolactone (PCL) and nanohydroxyapatite were used to fabricate three-dimensional porous scaffolds by adopting a combination of solvent casting, particulate leaching, and polymer leaching approaches. The PCL scaffold was subsequently surface modified by chemical bonding of 1,6-hexanediamine to the ester groups of PCL to introduce free NH2 groups. The introduction of NH2 groups as active sites enabled immobilization of biocompatible macromolecule, collagen, on the aminolyzed PCL via a cross-linking agent, glutaraldehyde. The osteoblasts' functions, notably cell adhesion, proliferation, and mineralization, were favorably modulated because of the chemical interaction between Arg-Gly-Asp domains in collagen molecule and integrin receptor in the cell membrane. The study underscores the significance of grafting collagen on PCL-nHA scaffold in modulating cellular activity and biological functions expanding its current use in soft tissue engineering to hard tissue regeneration. PMID:25691223

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

    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.

  6. Structure-Property Relationships for Electron-Vibrational Coupling in Conjugated Organic Oligomeric Systems

    O'Neill, Luke; Byrne, Hugh

    2005-01-01

    A series of ð-conjugated oligomers containing one to six monomer units were studied by absorption and photoluminescence spectroscopy. As is common for these systems, a linear relationship between the positioning of the lowest-energy absorption and the highest-energy photoluminescence maxima plotted versus inverse conjugation length is observed, in good agreement with a simple nearly free electron model, one of the earliest descriptions of the properties of one-dimensional organic molecules. I...

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

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

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

    Hule, Rohan A.

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

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

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

    2015-06-01

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

  10. Serum Albumin-Alginate Microparticles Prepared by Transacylation: Relationship between Physicochemical, Structural and Functional Properties.

    Hadef, Imane; Rogé, Barbara; Edwards-Lévy, Florence

    2015-08-10

    Our laboratory develops a method of microencapsulation using a transacylation reaction in a water-in-oil (W/O) emulsion. The method is based on the creation of amide bonds between free amine functions of a protein (human serum albumin (HSA)) and ester groups of propylene glycol alginate (PGA) in the inner aqueous phase after alkalization. The aim of this work is to study the influence of physicochemical properties of HSA-PGA mixtures on microparticle characteristics. Microparticles were prepared varying the concentrations of PGA and HSA, then characterized (inner structure, size, swelling rate, release kinetics). PGA and each polymer mixture used in the microencapsulation procedure were examined in order to elucidate the mechanism of microstructure formation. It was found that the morphology and functional properties of HSA-alginate microparticles were related to the two polymer concentrations in the aqueous solution. Actually, the polymer concentration variations led to physicochemical changes, which affected the microparticle structure and functional properties. PMID:26121308

  11. Relationship among forging technology, structure and properties of TC21 alloy bars

    QU Heng-lei; LI Hui; ZHANG Ying-nan; GUO Hong-chao; ZHOU Yi-gang; ZHOU Lian; ZHAO Yong-qing; ZENG Wei-dong; FENG Liang; YANG Yan-qing; CHEN Jun; YU Han-qing

    2005-01-01

    As candidate of structural material for advanced domestic aircraft, a new high strength and toughness titanium alloy TC21 was studied focusing on forging technology and microstructure as well as mechanical properties.Two specification ingots and bars were adopted. The results show that basket-weave microstructure is obtained in bars produced by beta finish-forging method; while duplex or tri-modal microstructure appears in bars manufactured by near-beta forging technology. Essential reason affecting structure characteristics is the difference in forging tem perature and deformation amount. Variation in lamellar spacing results in fluctuation of properties corresponding to basket-weave microstructure; however, ideal matching of properties can be reached by near-beta forging.

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

    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.

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

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

    2006-09-27

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

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

    Luxenhofer, Robert

    2011-07-01

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

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

    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.

  16. Structure/property relationships in HSLA steel with low carbon and manganese and increased silicon content

    KÖthe, A.; Richter, J.; Güth, A.; MÜsgen, B.; Baumgardt, H.

    1993-01-01

    The influence of an increased Si and reduced C and Mn content on structure and mechanical properties of HSLA steel plate with low carbon equivalent is investigated. With a C content of 0.06 ... 0.08 % Mn should be ≥ 0.8 %, and Si concentrations up to 1.0 % may be used. On air cooled 30 mm plate [MATH] has been obtained.

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

    Hyatt, N

    2000-01-01

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

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

    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. PMID:25366812

  19. Processing-structure-property relationships in electron beam physical vapor deposited yttria stabilized zirconia coatings

    The physical and mechanical properties of yttria stabilized zirconia (YSZ) coatings deposited by the electron beam physical vapor deposition technique have been investigated by varying the key process variables such as vapor incidence angle and sample rotation speed. The tetragonal zirconia coatings formed under varying process conditions employed were found to have widely different surface and cross-sectional morphologies. The porosity, phase composition, planar orientation, hardness, adhesion, and surface residual stresses in the coated specimens were comprehensively evaluated to develop a correlation with the process variables. Under transverse scratch test conditions, the YSZ coatings exhibited two different crack formation modes, depending on the magnitude of residual stress. The influence of processing conditions on the coating deposition rate, column orientation angle, and adhesion strength has been established. Key relationships between porosity, hardness, and adhesion are also presented.

  20. Observations on the relationship of structure to the mechanical properties of thin TD-NiCr sheet

    Whittenberger, J. D.

    1976-01-01

    A study of the relationship between structure and mechanical properties of thin TD-NiCr sheet indicated that the elevated temperature tensile, stress-rupture, and creep strength properties are dependent on grain aspect ratio and sheet thickness. In general, the strength properties increase with increasing grain aspect ratio and sheet thickness. Tensile testing revealed an absence of ductility at elevated temperatures (not less than 1144 K). Significant creep damage as determined by subsequent tensile testing at room temperature occurs after very small amounts (less than 0.1%) of prior creep deformation over the temperature range 1144-1477 K. A threshold stress for creep appears to exist. Creep exposure below the threshold stress at T not less than 1366 K results in almost full retention of room temperature tensile properties.

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

    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

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

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

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

  3. Supramolecular structure of jackfruit seed starch and its relationship with digestibility and physicochemical properties.

    Chen, Jin; Liang, Yi; Li, Xiaoxi; Chen, Ling; Xie, Fengwei

    2016-10-01

    The influence of supramolecular structure on the physicochemical properties and digestibility of jackfruit seed starch (JSS) were investigated. Compared with maize and cassava starches (MS and CS), JSS had smaller granules and higher amylose content (JSS: 24.90%; CS: 16.68%; and MS: 22.42%), which contributed to higher gelatinization temperature (To: 81.11°C) and setback viscosity (548.9mPas). From scanning electron microscopy, the digestion of JSS was observed mainly at the granule surface. Due to its higher crystallinity (JSS: 30.6%; CS: 30.3%; and MS: 27.4%) and more ordered semi-crystalline lamellae, JSS had a high RS content (74.26%) and melting enthalpy (19.61J/g). In other words, the supramolecular structure of JSS extensively determined its digestibility and resistance to heat and mechanical shear treatment. PMID:27312638

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

    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.

  5. Relationship Between Structure and Dynamic Mechanical Properties of a Carbon Nanofiber Reinforced Elastomeric Nanocomposite

    The tensile and dynamic mechanical properties of a nanocomposite, containing modified carbon nanofibers (MCNFs) homogenously dispersed in an elastomeric ethylene/propylene (EP) copolymer semicrystalline matrix (84.3 wt% P), have been correlated with the structure development. These properties were characterized by in situ synchrotron X-ray diffraction during stretching, dynamic mechanical analysis and X-ray analysis techniques over a wide temperature range. Upon sequential drawing, the tensile strength of the nanocomposite film was notably higher than that of the unfilled polymer even though both samples exhibited a similar amount of crystal fraction and the same degree of crystal orientation, revealing the effect of nanofiller reinforcement in the semicrystalline matrix. The mechanical spectra of the 10 wt% MCNF filled samples in both stretched and non-stretched states showed broadening of the elastic modulus at high temperatures, where the corresponding crystallinity index also decreased. It is conceivable that a significant fraction of chain orientation is induced in the vicinity of the nanofillers during stretching, and these stretched chains with reduced mobility significantly enhance the thermal mechanical properties

  6. Quantitative Structure–Property Relationships for Aryldiazonia

    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.

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

    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.

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

    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...

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

    Prichard, P.D.

    1998-02-23

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

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

    Jing, Hao

    In this dissertation, the rational design and controllable fabrication of an array of novel plasmonic nanostructures with geometrically tunable optical properties are demonstrated, including metal-semiconductor hybrid hetero-nanoparticles, bimetallic noble metal nanoparticles and hollow nanostructures (nanobox and nanocage). Firstly, I have developed a robust wet chemistry approach to the geometry control of Ag-Cu2O core-shell nanoparticles through epitaxial growth of Cu2O nanoshells on the surfaces of various Ag nanostructures, such as quasi-spherical nanoparticles, nanocubes, and nanocuboids. Precise control over the core and the shell geometries enables me to develop detailed, quantitative understanding of how the Cu2O nanoshells introduce interesting modifications to the resonance frequencies and the extinction spectral line shapes of multiple plasmon modes of the Ag cores. Secondly, I present a detailed and systematic study of the controlled overgrowth of Pd on Au nanorods. The overgrowth of Pd nanoshells with fine-controlled dimensions and architectures on single-crystalline Au nanorods through seed-mediated growth protocol in the presence of various surfactants is investigated. Thirdly, I have demonstrated that creation of high-index facets on subwavelength metallic nanoparticles provides a unique approach to the integration of desired plasmonic and catalytic properties on the same nanoparticle. Through site-selective surface etching of metallic nanocuboids whose surfaces are dominated by low-index facets, I have controllably fabricated nanorice and nanodumbbell particles, which exhibit drastically enhanced catalytic activities arising from the catalytically active high index facets abundant on the particle surfaces. And the nanorice and nanodumbbell particles also possess appealing tunable plasmonic properties that allow us to gain quantitative insights into nanoparticle-catalyzed reactions with unprecedented sensitivity and detail through time

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

    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.

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

    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.

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

    Xiu-Wen Wu

    2014-11-01

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

  14. Structure-property relationships for self-assembled zinc chlorin light-harvesting dye aggregates.

    Huber, Valerie; Sengupta, Sanchita; Würthner, Frank

    2008-01-01

    A series of zinc 3(1)-hydroxymethyl chlorins 10 a-e and zinc 3(1)-hydroxyethyl chlorins 17 with varied structural features were synthesized by modifying naturally occurring chlorophyll a. Solvent-, temperature-, and concentration-dependent UV/Vis and CD spectroscopic methods as well as microscopic investigations were performed to explore the importance of particular functional groups and steric effects on the self-assembly behavior of these zinc chlorins. Semisynthetic zinc chlorins 10 a-e possess the three functional units relevant for self-assembly found in their natural bacteriochlorophyll (BChl) counterparts, namely, the 3(1)-OH group, a central metal ion, and the 13(1) C==O moiety along the Qy axis, and they contain various 17(2)-substituents. Depending on whether the zinc chlorins have 17(2)-hydrophobic or hydrophilic side chains, they self-assemble in nonpolar organic solvents or in aqueous media, respectively. Zinc chlorins possessing at least two long side chains provide soluble self-aggregates that are stable in solution for a prolonged time, thus facilitating elucidation of their properties by optical spectroscopy. The morphology of the zinc chlorin aggregates was elucidated by atomic force microscopy (AFM) studies, revealing well-defined nanoscale rod structures for zinc chlorin 10 b with a height of about 6 nm. It is worth noting that this size is in good accordance with a tubular arrangement of the dyes similar to that observed in their natural BChl counterparts in the light-harvesting chlorosomes of green bacteria. Furthermore, for the epimeric 3(1)-hydroxyethyl zinc chlorins 17 with hydrophobic side chains, the influence of the chirality center at the 3(1)-position on the aggregation behavior was studied in detail by UV/Vis and CD spectroscopy. Unlike zinc chlorins 10, the 3(1)-hydroxyethyl zinc chlorins 17 formed only small oligomers and not higher rod aggregate structures, which can be attributed to the steric effect imposed by the additional

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

    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 (block copolymers with properties typical of thermoplastic elastomers. The block copolymers synthesized by chain shuttling technology consist of crystallizable ethylene-octene blocks with low comonomer content and high melting temperature (hard blocks), alternating with amorphous ethylene-octene blocks with high comonomer content and low glass transition temperature (soft blocks). This study describes the material science of these unique polymers as characterized by thermal analysis, X-ray diffraction, microscopy, and tensile deformation. The crystallizable blocks are long enough to form well-organized lamellar crystals with the orthorhombic unit cell and high melting temperature. The lamellae are organized into space-filling spherulites in all compositions even in copolymers with only 18 wt% hard block. The morphology is consistent

  16. Electron Backscatter Diffraction: An Important Tool for Analyses of Structure-Property Relationships in Thin-Film Solar Cells

    Abou-Ras, D.; Kavalakkatt, J.; Nichterwitz, M.; Schäfer, N.; Harndt, S.; Wilkinson, A. J.; Tsyrulin, K.; Schulz, H.; Bauer, F.

    2013-09-01

    The present work gives an overview of the application of electron backscatter diffraction (EBSD) in the field of thin-film solar cells, which consist of stacks of polycrystalline layers on various rigid or flexible substrates. EBSD provides access to grain-size and local-orientation distributions, film textures, and grain-boundary types. By evaluation of the EBSD patterns within individual grains of the polycrystalline solar cell layers, microstrain distributions also can be obtained. These microstructural properties are of considerable interest for research and development of thin-film solar cells. Moreover, EBSD may be performed three-dimensionally, by alternating slicing of cross sections in a focused ion-beam machine and EBSD acquisition. To relate the microstructural properties to the electrical properties of individual layers as well as to the device performances of corresponding solar cells, EBSD can be combined with electron-beam-induced current and cathodoluminescence measurements and with various scanning-probe microscopy methods such as Kelvin-probe force, scanning spreading resistance, or scanning capacitance microscopy on identical specimen positions. Together with standard device characterization of thin-film solar cells, these scanning microscopy measurements provide the means for extensive analysis of structure-property relationships in solar-cell stacks with polycrystalline layers.

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

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

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

    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 ...

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

    Wattebled, Laurent

    2007-01-01

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

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

    Yalamanchili, Phani Kumar

    2014-01-01

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

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

    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.

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

    Lejček, Pavel; Jäger, Aleš; Gärtnerová, Viera; Vaníčková, J.; Děd, J.; Haloda, J.

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

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

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

    2015-01-01

    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...... under alkaline electrochemical conditions. We demonstrate that the structure and oxidation state of the films can be systematically tuned by changing the applied electrode potential and/or the nature of substrates. Structural features determined from the theoretical calculations provide a wealth of...... 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...

  4. Onium salt structure/property relationships in poly(4-tert-butyloxycarbonyloxystyrene) deep-UV resists

    Schwartzkopf, George; Niazy, Nagla N.; Das, Siddhartha; Surendran, Geetha; Covington, John B.

    1991-06-01

    A series of sulfonium and iodonium salts was synthesized and the effect of onium slat structure on UV absorbance, thermal stability, and solubility in propylene glycol methyl ether acetate (PGMEA) was assessed. Several of these onium salts gave usable deep UV photoresists when combined with poly(4-tert-butyloxy-carbonloxystyrene). The lithographic sensitivity and latent image stability of these photoresists were strongly influenced by the structure of the incorporated onium salt.

  5. Structure-Property-Transfection Relationships in Polycation-mediated Non-viral DNA Delivery

    Layman, John

    2008-01-01

    Non-viral gene delivery agents, such as cationic polyelectrolytes, are attractive replacements to viruses due to the absence of potential immunogenic risk and the ability to tune their macromolecular structure. Although non-viral vectors possess numerous design advantages, several investigators have shown that transfer efficiencies are considerably lower when compared to viral vectors. The work reported in this dissertation aims to fundamentally understand the underlying structure-transfect...

  6. Structure-property relationships in thermomechanically treated beryllia dispersed nickel alloys

    BeO dispersed nickel alloys, produced by powder metallurgy techniques, were studied extensively in stress rupture at 815, 982, and 10930C (1088, 1255, and 1366 K) and by transmission electron microscopy. The alloys were subjected to a variety of thermomechanical treatments (TMT) to determine the benefits of TMT on properties. It is shown that the use of intermediate annealing treatments after 10 percent reduction steps is highly beneficial on both low and high temperature properties. It is indicated that the high temperature strength is not primarily dependent on the grain aspect ratio or texture but depends strongly on the dislocation density and distribution of dislocations in a stable substructure which is pinned by the fine oxide dispersion. (22 fig) (U.S.)

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

    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.

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

    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.

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

    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

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

    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

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

    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)

  12. Application of structure-property relationships to develop seven segmented polyurethane adhesives

    Hoffman, D.M.; Hammon, H.G.; Althouse, L.P.

    1981-01-01

    Seven polyurethane adhesives have been developed to meet a series of design requirements for weapons. These adhesives, designated Halthanes, were synthesized because of OSHA restrictions on the use of the curing agent methylene bis(2- chloroaniline) with the objective of meeting qualitative design requirements. Four of the Halthanes were made from LLNL-developed 4,4'-methylene bis(phenylisocyanate) terminated prepolymers cured with a blend of polyols; three were made from an LLNL-developed prepolymer terminated with Hylene W and cured with aromatic diamines. Changes in the structure of prepolymer, curing agent and accelerator were made to achieve initial viscosities in the range of 6 and 40 Pa-sec, and working times of from 4 to 24 hours. The structure of the polymer/substrate interface was used to obtain adhesive strengths of from 8 to 14 MPa at room temperature. The morphology and concentration of the hard and soft segments were used to control the modulus and elasticity of these segmented polyurethanes. Seven polyurethane adhesives have been developed that bond rapidly and well, have low to intermediate modulus over a wide temperature range, and appear to be reasonably compatible with other components.

  13. The Structure-Property Relationship of Poly(amide-imide)/Organoclay Nanocomposites

    Faghihi, Khalil; Soleimani, Masoumeh; Shabanian, Meisam; Abootalebi, Ashraf Sadateh

    2011-06-01

    Surface treated montmorillonite (MMT) was used to prepare nanocomposites with poly(amide-imide) (PAI) 5 by solution intercalation technique with various percent of organoclay (5-15 mass %). Surface modification of the MMT was performed with Cloisite 20A for ample compatibilization with the PAI matrix. The PAI 5 chains were produced through polycondensation of 4,4-diamino diphenyl sulfone 4 with N-trimellitylimido-L-alanine 3 in a medium consisting of triphenyl phosphite, N-methyl-2-pyrolidone (NMP), pyridine and calcium chloride. The PAI-Nanocomposites morphology and clay dispersion were investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and PAI chains on the properties of PAI-Nanocomposites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements. Thermal stability of nanocomposites increased relative to the neat polyamide with increasing organoclay content but water uptake of these materials decreased as compared to the neat polyamide indicating reduced permeability.

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

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

    2015-02-01

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

  15. Parallel high-throughput screening of polymer vectors for nonviral gene delivery: evaluation of structure-property relationships of transfection.

    Rinkenauer, Alexandra C; Vollrath, Antje; Schallon, Anja; Tauhardt, Lutz; Kempe, Kristian; Schubert, Stephanie; Fischer, Dagmar; Schubert, Ulrich S

    2013-09-01

    In recent years, "high-throughput" (HT) has turned into a keyword in polymer research. In this study, we present a novel HT workflow for the investigation of cationic polymers for gene delivery applications. For this purpose, various poly(ethylene imine)s (PEI) were used as representative vectors and investigated via HT-assays in a 96-well plate format, starting from polyplex preparation up to the examination of the transfection process. In detail, automated polyplex preparation, complex size determination, DNA binding affinity, polyplex stability, cytotoxicity, and transfection efficiency were performed in the well plate format. With standard techniques, investigation of the biological properties of polymers is quite time-consuming, so only a limited number of materials and conditions (such as pH, buffer composition, and concentration) can be examined. The approach described here allows many different polymers and parameters to be tested for transfection properties and cytotoxicity, giving faster insights into structure-activity relationships for biological activity. PMID:23886244

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

    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

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

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

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

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

    2011-10-17

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

  19. Excited States and photodebromination of selected polybrominated diphenyl ethers: computational and quantitative structure--property relationship studies.

    Luo, Jin; Hu, Jiwei; Wei, Xionghui; Li, Lingyun; Huang, Xianfei

    2015-01-01

    This paper presents a density functional theory (DFT)/time-dependent DFT (TD-DFT) study on the lowest lying singlet and triplet excited states of 20 selected polybrominateddiphenyl ether (PBDE) congeners, with the solvation effect included in the calculations using the polarized continuum model (PCM). The results obtained showed that for most of the brominated diphenyl ether (BDE) congeners, the lowest singlet excited state was initiated by the electron transfer from HOMO to LUMO, involving a π-σ* excitation. In triplet excited states, structure of the BDE congeners differed notably from that of the BDE ground states with one of the specific C-Br bonds bending off the aromatic plane. In addition, the partial least squares regression (PLSR), principal component analysis-multiple linear regression analysis (PCA-MLR), and back propagation artificial neural network (BP-ANN) approaches were employed for a quantitative structure-property relationship (QSPR) study. Based on the previously reported kinetic data for the debromination by ultraviolet (UV) and sunlight, obtained QSPR models exhibited a reasonable evaluation of the photodebromination reactivity even when the BDE congeners had same degree of bromination, albeit different patterns of bromination. PMID:25569092

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

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

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

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

    2014-04-01

    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. PMID:24620787

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

    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.

  3. 2D Quantitative Structure-Property Relationship Study of Mycotoxins by Multiple Linear Regression and Support Vector Machine

    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.

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

    Krein, Michael

    2011-01-01

    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…

  5. The electronic structure and second-order nonlinear optical properties of donor-acceptor acetylenes - A detailed investigation of structure-property relationships

    Stiegman, A. E.; Graham, Eva; Khundkar, Lutfur R.; Perry, Joseph W.; Cheng, L.-T.; Perry, Kelly J.

    1991-01-01

    A series of donor-acceptor acetylene compounds was synthesized in which systematic changes in both the conjugation length and the donor-acceptor strength were made. The effect of these structural changes on the spectroscopic and electronic properties of the molecules and, ultimately, on the measured second-order molecular hyperpolarizabilities (beta) was investigated. It was found that increases in the donor-acceptor strength resulted in increases in the magnitude of beta. For this class of molecules, the increase is dominated by the energy of the intramolecular charge-transfer transition, while factors such as the ground to excited-state dipole moment change and the transition-moment integral are much less important. Increasing the conjugation length from one to two acetylene linkers did not result in an increase in the value of beta; however, beta increased sharply in going from two acetylenes to three. This increase is attributed to the superposition of several nearly isoenergetic excited states.

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

    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.

  7. Development of Quantitative Structure-Property Relationship Models for Self-Emulsifying Drug Delivery System of 2-Aryl Propionic Acid NSAIDs

    Chen-Wen Li; Sheng-Yong Yang; Rui He; Wan-Jun Tao; Zong-Ning Yin

    2011-01-01

    We developed the quantative structure-property relationships (QSPRs) models to correlate the molecular structures of surfactant, cosurfactant, oil, and drug with the solubility of poorly water-soluble 2-aryl propionic acid nonsteroidal anti-inflammatory drugs (2-APA-NSAIDs) in self-emulsifying drug delivery systems (SEDDSs). The compositions were encoded with electronic, geometrical, topological, and quantum chemical descriptors. To obtain reliable predictions, we used multiple linear regress...

  8. The Relationship Satisfaction scale – Psychometric properties

    Espen Røysamb

    2014-12-01

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

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

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

    2014-01-01

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

  10. Relationship of binding specificity and structural property of the technetium-99m complexes for tumor hypoxia and tumor angiogenesis imaging

    The growth of tumor requires nutrition and oxygen. Tumor cells will become hypoxic when the supply of oxygen is insufficient. Hypoxic tumor cells will not only resist radiation therapy and chemotherapy, but also induce angiogenesis for oxygen supply and for metastasis. Therefore, detection of tumor hypoxia and tumor angiogenesis with high sensitive radio labeled imaging agents is important. Hypoxic tumor cells may display some molecules as tumor markers for the specific binding with radiopharmaceuticals. Radiopharmaceuticals, unlike the non-radioactive drugs, are trace compounds in a given dosage. Due to the extreme low concentration, the non-specific accumulation of the radiotracers by blood cells and proteins, tissues, and organs can be even more serious compared to the non-radioactive drugs. The non-specific accumulation of the radiotracers can make the ratios of tumor/tissue (in terms of i.d.%/g) falling to the range of 2∼7 [1-2]. Non-specific binding of radiopharmaceuticals is common, but detailed studies on it are poor documented. This presentation reports the study of the relationship of non-specific accumulation and the structural property of two type of 99mTC labeled compounds: (a) 99mTc-(amineoxime) containing either 2-nitroimidazole (2-NI, as hypoxia tumor cells specific agents), or 4-nitro- imidazole (4-NI, as control), or aniline (as reference) groups; (b) 99mTc-(arginine-glycine- aspartic acid, RGD, as tumor angiogenesis specific agents) and 99mTc-(arginine-glycine- glutarmic acid, RGE, as control). The 99mTc-(amine-oxime) complexes, in addition to the 2-NI, 4-NI, and aniline groups, contain methyl-, ethyl-, propyl-, iso-butyl-, t-butyl-, phenyl-, and Benzyl- groups as well to make the radiotracers differing in structure and in lipophilicity , while the lipophilicity of a radiotracer plays an important role in non-specific cellular accumulation and protein binding, The results demonstrated that (1) the complex containing 2-NI showed specific

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

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

    2015-11-28

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

  12. A best​ comprehension about the toxicity of phenylsulfonyl carboxylates in Vibrio fischeri using quantitative structure activity/property relationship methods.

    de Melo, Eduardo Borges; Martins, João Paulo Athaíde; Miranda, Eduardo Hösel; Ferreira, Márcia Miguel Castro

    2016-03-01

    Aromatic sulfones comprise a class of chemicals used in agrochemical and pharmaceutical industries and as floatation and extractant agents in petrochemical and metallurgy industries. In this study, new QSA(P)R studies were carried out to predict the toxicity against Vibrio fischeri of a set of 52 aromatic sulfones. The same approach was used to evaluate the relationship between these endpoint and the water solubility, another important environmental endpoint. The study resulted in models of good statistical quality and mechanistic interpretation with a possible correlation between the two endpoints, but the toxic effect is also likely to depend on other physicochemical properties. The use of the PLS2, a method not commonly used in QSA(P)R studies, also produced models of greater reliability, and the relationship between the two endpoints was reinforced to some degree. These results are useful for better understanding the process by which these compounds exert their environmental toxicity, thus aiding in the development of industrially useful compounds with less potential environmental damage. PMID:26551227

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

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

  14. Synthesis, growth, vibrational spectral investigations and structure-property relationship of an organic NLO crystal: 3,4-Dimethoxy chalcone

    Alen, S.; Sajan, D.; Joseph, Lynnette; Chaitanya, K.; Shettigar, Venkataraya; Jothy, V. Bena

    2015-09-01

    3,4-Dimethoxy chalcone, a nonlinear optical material, was synthesized and noncentro symmetric single crystals were grown in solution by slow evaporation technique. Thermal analysis such as DSC revealed a good thermal stability of 3,4-dimethoxy chalcone. The FT-IR and FT-Raman spectral studies were carried out to investigate the structural properties of the title compound. The molecular orbitals and natural bond analysis of this material were calculated by Density Functional Theory calculations. The second harmonic conversion efficiency was determined using the Kurtz powder technique, which is 8 times that of urea.

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

    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.

  16. Structure-activity relationships of novel salicylaldehyde isonicotinoyl hydrazone (SIH analogs: iron chelation, anti-oxidant and cytotoxic properties.

    Eliška Potůčková

    Full Text Available Salicylaldehyde isonicotinoyl hydrazone (SIH is a lipophilic, tridentate iron chelator with marked anti-oxidant and modest cytotoxic activity against neoplastic cells. However, it has poor stability in an aqueous environment due to the rapid hydrolysis of its hydrazone bond. In this study, we synthesized a series of new SIH analogs (based on previously described aromatic ketones with improved hydrolytic stability. Their structure-activity relationships were assessed with respect to their stability in plasma, iron chelation efficacy, redox effects and cytotoxic activity against MCF-7 breast adenocarcinoma cells. Furthermore, studies assessed the cytotoxicity of these chelators and their ability to afford protection against hydrogen peroxide-induced oxidative injury in H9c2 cardiomyoblasts. The ligands with a reduced hydrazone bond, or the presence of bulky alkyl substituents near the hydrazone bond, showed severely limited biological activity. The introduction of a bromine substituent increased ligand-induced cytotoxicity to both cancer cells and H9c2 cardiomyoblasts. A similar effect was observed when the phenolic ring was exchanged with pyridine (i.e., changing the ligating site from O, N, O to N, N, O, which led to pro-oxidative effects. In contrast, compounds with long, flexible alkyl chains adjacent to the hydrazone bond exhibited specific cytotoxic effects against MCF-7 breast adenocarcinoma cells and low toxicity against H9c2 cardiomyoblasts. Hence, this study highlights important structure-activity relationships and provides insight into the further development of aroylhydrazone iron chelators with more potent and selective anti-neoplastic effects.

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

    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...

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

    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

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

    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

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

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

    2015-09-01

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

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

    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.

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

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

  3. Development of Quantitative Structure-Property Relationship Models for Self-Emulsifying Drug Delivery System of 2-Aryl Propionic Acid NSAIDs

    Chen-Wen Li

    2011-01-01

    Full Text Available We developed the quantative structure-property relationships (QSPRs models to correlate the molecular structures of surfactant, cosurfactant, oil, and drug with the solubility of poorly water-soluble 2-aryl propionic acid nonsteroidal anti-inflammatory drugs (2-APA-NSAIDs in self-emulsifying drug delivery systems (SEDDSs. The compositions were encoded with electronic, geometrical, topological, and quantum chemical descriptors. To obtain reliable predictions, we used multiple linear regression (MLR and artificial neural network (ANN methods for model development. The obtained equations were validated using a test set of 42 formulations and showed a great predictive power, and linear models were found to be better than nonlinear ones. The obtained QSPR models would greatly facilitate fast screening for the optimal formulations of SEDDS at the early stage of drug development and minimize experimental effort.

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

    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.

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

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

    2014-10-20

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

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

    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.

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

    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.

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

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

  9. Relationship between crystal structure and luminescent properties of novel red emissive BiVO4:Eu3+ and its photocatalytic performance

    Crystalline BiVO4:Eu3+ nanomaterials have been successfully synthesized by four different methods: co-precipitation, hydrothermal, solvothermal, and reverse micelles. The relationship between crystal structure and luminescent properties was studied by X-ray diffraction and steady-state fluorescence. The data indicate that Eu3+5D0 → 7F2 red luminescence at 618 nm can be excited by visible light at 466 nm in BiVO4 host. Furthermore, it has been found that the encapsulation of europium(III) in tetragonal phase (BiVO4) results in enhanced luminescence intensities compared with monoclinic phase. Transmission electron microscopy showed rods with sizes ranging from nanometer to micrometer and nanospheres can be obtained under different experimental conditions.

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

    Ghasemi, Jahanbakhsh [Chemistry Department, Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of)], E-mail: Jahan.ghasemi@gmail.com; Saaidpour, Saadi [Chemistry Department, Faculty of Sciences, Razi University, Kermanshah (Iran, Islamic Republic of)

    2007-12-05

    A quantitative structure-property relationship (QSPR) study was performed to develop models those relate the structures of 150 drug organic compounds to their n-octanol-water partition coefficients (log P{sub o/w}). Molecular descriptors derived solely from 3D structures of the molecular drugs. A genetic algorithm was also applied as a variable selection tool in QSPR analysis. The models were constructed using 110 molecules as training set, and predictive ability tested using 40 compounds. Modeling of log P{sub o/w} of these compounds as a function of the theoretically derived descriptors was established by multiple linear regression (MLR). Four descriptors for these compounds molecular volume (MV) (geometrical), hydrophilic-lipophilic balance (HLB) (constitutional), hydrogen bond forming ability (HB) (electronic) and polar surface area (PSA) (electrostatic) are taken as inputs for the model. The use of descriptors calculated only from molecular structure eliminates the need for experimental determination of properties for use in the correlation and allows for the estimation of log P{sub o/w} for molecules not yet synthesized. Application of the developed model to a testing set of 40 drug organic compounds demonstrates that the model is reliable with good predictive accuracy and simple formulation. The prediction results are in good agreement with the experimental value. The root mean square error of prediction (RMSEP) and square correlation coefficient (R{sup 2}) for MLR model were 0.22 and 0.99 for the prediction set log P{sub o/w}.

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

    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.

  12. Probing Carrier Transport and Structure-Property Relationship of Highly Ordered Organic Semiconductors at the Two-Dimensional Limit

    Zhang, Yuhan; Qiao, Jingsi; Gao, Si; Hu, Fengrui; He, Daowei; Wu, Bing; Yang, Ziyi; Xu, Bingchen; Li, Yun; Shi, Yi; Ji, Wei; Wang, Peng; Wang, Xiaoyong; Xiao, Min; Xu, Hangxun; Xu, Jian-Bin; Wang, Xinran

    2016-01-01

    One of the basic assumptions in organic field-effect transistors, the most fundamental device unit in organic electronics, is that charge transport occurs two dimensionally in the first few molecular layers near the dielectric interface. Although the mobility of bulk organic semiconductors has increased dramatically, direct probing of intrinsic charge transport in the two-dimensional limit has not been possible due to excessive disorders and traps in ultrathin organic thin films. Here, highly ordered single-crystalline mono- to tetralayer pentacene crystals are realized by van der Waals (vdW) epitaxy on hexagonal BN. We find that the charge transport is dominated by hopping in the first conductive layer, but transforms to bandlike in subsequent layers. Such an abrupt phase transition is attributed to strong modulation of the molecular packing by interfacial vdW interactions, as corroborated by quantitative structural characterization and density functional theory calculations. The structural modulation becomes negligible beyond the second conductive layer, leading to a mobility saturation thickness of only ˜3 nm . Highly ordered organic ultrathin films provide a platform for new physics and device structures (such as heterostructures and quantum wells) that are not possible in conventional bulk crystals.

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

    Rathmell, Aaron R.

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

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

    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

  15. Structure-property relationships of mullite-SiC-Al2O3–ZrO2 composites developed during carbothermal reduction of aluminosilicate minerals

    Evolution of SiC and ZrO2 in the matrix of Al2O3 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-Al2O3 matrix composites have been investigated in conjunction with the evolution of reinforcing phases such as SiC–ZrO2 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/SiO2 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/SiO2 ratio in starting materials, very fine SiC whiskers have been formed in the microstructures. Moreover, the densification and strength are considerable higher for ZrO2 + SiC containing composites in comparison to that of only SiC added ones. Furthermore, it has been found that the appropriate ratio of C/SiO2 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 materials for high temperature applications

  16. Structure-Property Relationship for Two-Photon Absorbing Multiporphyrins: Supramolecular Assembly of Highly-Conjugated Multiporphyrinic Ladders and Prisms

    Easwaramoorthi, Shanmugam; Jang, So Young; Yoon, Zin Seok; Lim, Jong Min; Lee, Cheng-Wei; Mai, Chi-Lun; Liu, Yen-Chun; Yeh, Chen-Yu; Vura-Weis, Josh; Wasielewski, Michael R.; Kim, Dongho (NWU); (Yonsei); (NSHU)

    2008-10-03

    Two-photon absorption (TPA) phenomena of a series of single-strand as well as supramolecular self-assembled ladders and prisms of highly conjugated ethyne bridged multiporphyrin dimer, trimer, and star shaped pentamer have been investigated. The ligand mediated self-assembled supramolecular structures were characterized by UV-visible spectroscopy and small- and wide-angle X-ray scattering (SAXS/WAXS) analysis. The TPA cross section values of multiporphyrins increase nonlinearly from {approx}100 to {approx}18000 GM with an increased number of porphyrin units and elongated ?-conjugation length by virtue of charge transfer and excited-state cumulenic configurations. The observed opposite TPA behavior between their supramolecular ladder and prism configurations necessitates the importance of interstrand interactions between the multiporphyrinic units and the overall shape of the assembly. Furthermore, the diminished TPA cross section of the pentamer, despite the increased ?-conjugation resulting from duplex formation suggests that destabilizing the essential functional configurations at the cost of elongation of ?-delocalization pathway must cause unfavorable effects. We have also shown that one- and two-photon allowed energy-levels of linear multiporphyrins are nearly isoenergetic and the latter transition originates exclusively from the extent of ?-delocalization within the molecule. The identical TPA maximum position of the trimer and pentamer indicates that the TPA of the pentamer arises only from its basic trimer unit in spite of its extended two-dimensional {pi}-conjugation pathway involving five porphyrinic units.

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

    S. K. Singh

    2009-10-01

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

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

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

    2015-01-01

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

  19. Phase relationship, structural and magnetic properties of Nd-deficient Nd0.95-xCaxMnO2.93±δ

    Estemirova, Svetlana; Mitrofanov, Valentin; Kozhina, Galina; Fetisov, Andrew

    2016-02-01

    Phase relationships in Nd-deficient solid solutions Nd0.95-xCaxMnO2.93±δ (x=0.00, 0.05, 0.10, 0.15, 0.20) were investigated in the temperature range T=800-1100 °C in air and under reduced oxygen partial pressure (at T=1000 °C). Phase diagrams in the coordinates "Temperature-calcium content" and "Po2-calcium content" were constructed. The boundaries of two-phase regions on the phase diagrams were defined.The oxidation mechanism and the stability conditions for the perovskite structure were determined.The magnetic properties of single phase samples with x=0, 0.1, 0.2 have been studied as a function of temperature and magnetic field. The observed magnetic anomalies: magnetization sign reversal and spin-reorientation transitions are compatible with the coexistence of AFM and FM phases, clusters of different nature, quasi heterogeneity (presence of clusters enriched/depleted with neodymium or manganese oxide). Quadrupole centers are considered as a source of spin inversion phenomena.

  20. Linear and nonlinear quantitative structure-property relationship models for solubility of some anthraquinone, anthrone and xanthone derivatives in supercritical carbon dioxide.

    Hemmateenejad, Bahram; Shamsipur, Mojtaba; Miri, Ramin; Elyasi, Maryam; Foroghinia, Farzaneh; Sharghi, Hashem

    2008-03-01

    A quantitative structure-property relation (QSPR) study was conducted on the solubility in supercritical fluid carbon dioxide (SCF-CO2) of some recently synthesized anthraquinone, anthrone and xanthone derivatives. The data set consisted of 29 molecules in various temperatures and pressures, which form 1190 solubility data. The combined data splitting-feature selection (CDFS) strategy, which previously developed in our research group, was used as descriptor selection and model development method. Modeling of the relationship between selected molecular descriptors and solubility data was achieved by linear (multiple linear regression; MLR) and nonlinear (artificial neural network; ANN) methods. The QSPR models were validated by cross-validation as well as application of the models to predict the solubility of three external set compounds, which did not have contribution in model development steps. Both linear and nonlinear methods resulted in accurate prediction whereas more accurate results were obtained by ANN model. The respective root mean square error of prediction obtained by MLR and ANN models were 0.284 and 0.095 in the term of logarithm of g solute m(-3) of SCF-CO2. A comparison was made between the models selected by CDFS method and the conventional stepwise feature selection method. It was found that the latter produced models with higher number of descriptors and lowered prediction ability, thus it can be considered as an over-fitted model. PMID:18267136

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

    de Melo, Eduardo Borges

    2012-01-01

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

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

    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.

  3. Structure-property relationships in redox-gated single molecule junctions - A comparison of pyrrolo-tetrathiafulvalene and viologen redox groups

    Leary, E.; Higgins, S.J.; van Zalinge, H.; Haiss, W.; Nichols, Richard John; Nygaard, Sune; Jeppesen, Jan Oskar; Ulstrup, Jens

    2008-01-01

    We demonstrate that the electrical 'switching" behavior of single molecules connected between two electrode contacts can be controlled by altering their structure and electrochemical characteristics. The electrical properties of gold vertical bar molecule vertical bar gold single molecule junctio...

  4. The synthesis, characterization, and structure-property relationships of regioregular 4,4'-dialkyl-2,2'-bithiazole oligomers and polymers

    Nanos, John I.

    2005-12-01

    The 4,4'-dialkyl-2,2'-bithiazole moiety can be efficiently coupled to produce well-defined oligomers or block co-oligomers via Stille reactions of mono-bromo and tin substituted precursors. Dehalogenative polycondensations produce high molecular weight homo-polymers and Stille coupling of dibromo and di-tin monomers yields alternating copolymers. The symmetry of the bithiazole monomeric unit produces regioregular oligomers and polymers with the HH-TT dyad sequence. Model compound oligomers were synthesized and studied to explore the progression of structure property relationships with main chain extension. DSC measurements indicate the potential presence of at least three phases in solution cast thin films---the disordered isotropic melt, a stable low temperature morphology designated the alpha-phase, and a high temperature meta-stable morphology designated the beta-phase. Melt transition temperatures are inversely proportional to side alkyl chain length and directly proportional to main chain length and the interplay between the two effects greatly influences the observed thermochromism. Temperature dependent IR studies show an increase in the gauche conformations of the side chains at the low temperature alpha-beta phase transition and main chain twisting at the beta-isotropic transition. The onset of side chain and main chain motion at these phase transition temperatures was confirmed with variable temperature solid state NMR. Temperature dependent XRD results indicate the presence of a solid-to-solid crystal phase change at the low temperature transition followed by formation of preferred orientations of the beta and alpha ordered phases upon cooling from the isotropic melt. The solid-to-solid crystal phase transition is triggered by the increased motion of the side chains, and the magnitude of the intermolecular side chain packing forces dictate if the transitions occur cooperatively (observed isosbestic point) or as isolated events. Comparison with the 3

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

    Thygesen, Lisbeth Garbrecht; Eder, M.; Burgert, I.

    2007-01-01

    did not affect the mechanical properties. In the second part of the study it was found that dislocations disappeared during tensile testing, and that they did not reappear until several weeks after failure. A strain stiffening effect due to the straightening of the dislocations was not observed. It is......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...

  6. Structural Antitumoral Activity Relationships of Synthetic Chalcones

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

    2009-01-01

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

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

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

    2007-01-01

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

  8. Structure-Property Relationships in CO2-philic (Co)polymers: Phase Behavior, Self-Assembly, and Stabilization of Water/CO2 Emulsions.

    Girard, Etienne; Tassaing, Thierry; Marty, Jean-Daniel; Destarac, Mathias

    2016-04-13

    This Review provides comprehensive guidelines for the design of CO2-philic copolymers through an exhaustive and precise coverage of factors governing the solubility of different classes of polymers. Starting from computational calculations describing the interactions of CO2 with various functionalities, we describe the phase behavior in sc-CO2 of the main families of polymers reported in literature. The self-assembly of amphiphilic copolymers of controlled architecture in supercritical carbon dioxide and their use as stabilizers for water/carbon dioxide emulsions then are covered. The relationships between the structure of such materials and their behavior in solutions and at interfaces are systematically underlined throughout these sections. PMID:27014998

  9. Porous Materials - Structure and Properties

    Nielsen, Anders

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

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

    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.

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

    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...

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

    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.

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

    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.

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

    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

  15. Structural graphite and its properties

    Considered is the technology of the structural graphite production for the reactor equipment and its effect on the graphite properties. Shown is the effect of porosity, formed at different stages of graphite production, on its strength and elasticity properties, and also the effect of the processing temperature on the crystal lattice parameter and physical properties of graphite obtained. The analysis of the dependence of graphite physical properties on its structural characteristics shows that well-expressed anizotropy of graphite physico-mechanical properties is caused by its hexagonal, laminated structure, by the orientation of grains and inclusions, and by the direction of micro- and macrodefects, as well

  16. On the relationship between the structure of self-assembled carboxylic acid monolayers on alumina and the organization and electrical properties of a pentacene thin film

    Lang, Philippe; Mottaghi, Daniel; Lacaze, Pierre-Camille

    2016-03-01

    The modification of insulating surfaces by self-assembled monolayers (SAMs) is an elegant way of tailoring the gate dielectric of organic field effect transistors (OFET) to pentacene and is commonly used to improve electrical performance. A SAM based on an alkylcarboxylic acid deposited on a thin layer of alumina, serving as the gate dielectric is considered. The relationship between carrier mobility and (i) the length of the carboxylic acid (CH3(CH2)nCOOH; n = 9, 14, 18), (ii) substrate preparation and (iii) the SAM and pentacene thin film structures is considered. The size and boundaries of pentacene grains are not limiting factors for carrier mobility, and the most relevant parameter, which depends on whether there is a SAM or not, is the organization of the first pentacene layers in contact with the gate dielectric. The variation of the interplanar distance d(0 0 1) of the pentacene layers close to the alumina surface is much greater without SAM than with, and this could explain the lower carrier mobility observed in the case of a bare alumina dielectric. The relationship between the disorder associated with this variation and mobility is discussed.

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

    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. PMID:18228598

  18. Structure-Activity Relationships of JMV4463, a Vectorized Cathepsin D Inhibitor with Antiproliferative Properties: The Unique Role of the AMPA-Based Vector.

    Vezenkov, Lubomir L; Sanchez, Clément A; Bellet, Virginie; Martin, Vincent; Maynadier, Marie; Bettache, Nadir; Lisowski, Vincent; Martinez, Jean; Garcia, Marcel; Amblard, Muriel; Hernandez, Jean-François

    2016-02-01

    Cathepsin D (CathD) is overexpressed and secreted by several solid tumors and stimulates their growth, the mechanism of which is still not understood. In this context, the pepstatin bioconjugate JMV4463 [Ac-arg-O2 Oc-(Val)3-Sta-Ala-Sta-(AMPA)4-NH2; O2 Oc=8-amino-3,6-dioxaoctanoyl, Sta=statine, AMPA=ortho-aminomethylphenylacetyl], containing a new kind of cell-penetrating vector, was previously shown to exhibit potent antiproliferative effects in vitro and to delay the onset of tumors in vivo. In this study, we performed a structure-activity relationship analysis to evaluate the significance of the inhibitor and vector moieties of JMV4463. By modifying both statine residues of pepstatin we found that the antiproliferative activity is correlated with CathD inhibition, supporting a major role of the catalytic activity of intracellular CathD in cancer cell proliferation. Replacing the vector composed of four AMPA units with other vectors was found to abolish cytotoxicity, although all of the conjugates enabled pepstatin transport into cells. In addition, the AMPA4 vector must be localized at the C terminus of the bioconjugate. The unexpected importance of the vector structure and position for cytotoxic action suggests that AMPA4 enables pepstatin to inhibit the proteolysis of critical CathD substrates involved in cell proliferation via a unique mechanism of action. PMID:26639308

  19. Porous Materials - Structure and Properties

    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...

  20. Structure-cytotoxicity relationships for dietary flavonoids

    Breinholt, V.; Dragsted, L.O.

    1998-01-01

    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...

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

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

    2012-01-01

    Research on psychosocial influences such as relationship characteristics has received increased attention in the clinical as well as social-psychological field. Several studies demonstrated that the quality of relationships, in particular with respect to the perceived support within intimate relationships, profoundly affects individuals' mental and physical health. There is, however, a limited choice of valid and internationally known assessments of relationship quality in Germany. We report ...

  2. Electromechanical actuation of buckypaper actuator: Material properties and performance relationships

    Carbon nanotubes can be assembled into macroscopic thin film materials called buckypapers. To incorporate buckypaper actuators into engineering systems, it is of high importance to understand their material property-actuation performance relationships in order to model and predict the behavior of these actuators. The electromechanical actuation of macroscopic buckypaper structures and their actuators, including single and multi-walled carbon nanotube buckypapers and aligned single-walled nanotube buckypapers, were analyzed and compared. From the experimental evidence, this Letter discusses the effects of the fundamental material properties, including Young modulus and electrical double layer properties, on actuation performance of the resultant actuators. -- Highlights: ► In this study we identified the figure of merit of the electromechanical conversion. ► Different type of buckypaper was realized and characterized for actuation properties. ► The results demonstrated the potential of Buckypapers/Nafion for actuation

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

    Nadia A. Mohamed

    2012-11-01

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

  4. The relationship between the electronic structure and thermoelectric properties of Zintl compounds M2Zn5As4 (M = K, Rb).

    Yang, Gui; Yang, Jueming; Yan, Yuli; Wang, Yuanxu

    2014-03-28

    The electronic structure and the thermoelectric properties of M2Zn5As4 (M = K, Rb) are studied by the first principles and the semiclassical BoltzTraP theory. It is determined that they are semiconductors with an indirect band gap of about 1 eV, which is much larger than that of Ca5Al2Sb6 (0.50 eV). The calculated electronic localization function indicates that they are typical Zintl bonding compounds. The combination of heavy and light bands near the valence band maximum may improve their thermoelectric performance. Rb2Zn5As4 exhibits relatively large Seebeck coefficients, high electrical conductivities, and the large "maximum" thermoelectric figures of merit (ZeT). Compared with Ca5Al2Sb6, the highest ZeT of Rb2Zn5As4 appears at relatively low carrier concentration. For Rb2Zn4As5, the p-type doping may achieve a higher thermoelectric performance than n-type doping. The thermoelectric properties of Rb2Zn5As4 are possibly superior to those of Ca5Al2Sb6. PMID:24522347

  5. Structured Questionnaire To Measure Therapeutic Relationship

    FatemehKhoshnavafomani

    2012-10-01

    Full Text Available The study attempts to develop and validate a new instrument to measure therapeutic relationship for use with high hospital principals and hospital employees. By using the three domains of therapeutic relationship, namely Patient factor, Therapist factors and Environmental factors, a primary questionnaire with 142 – item was developed and tested based on a sample of 250 hospital employees drawn from 4 hospitals representing in Iran. KMO Measure of Sampling Adequacy (.832 and Bartlett's Test of Sphericity (1345.32 and Analysis of Scree Plot have shown that the properties of sample are appropriate for factor analysis. Factor analysis for the final items items were made from which 64 items were extracted which had factor loading of >0.5 on the four domains. The properties of reliability and validity have borne significant results which show this instrument can be considered suitable to determine the position of therapeutic relationship in hospital employees.

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

    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.

  7. Study of the relationship between the crystal structure of nanolayers and electrical properties in AlxGa1−xAs/InyGa1−yAs pseudobinary heterostructures by double-crystal X-ray diffraction

    The structural parameters of individual layers of samples of a AlxGa1−xAs/InyGa1−yAs/GaAs pseudomorphic heterostructure have been determined by double-crystal X-ray diffraction. A relationship of the technological parameters of fabrication of heterostructures with their structural and electrical properties is established. The increase in the mobility of the 2D electron gas in the samples under study, caused by the increase in the growth temperature of the AlxGa1−xAs spacer layer and the decrease in the time of silicon δ doping from the two sides of the quantum well, correlates well with the degree of the sample structural quality.

  8. Structure-property relationships in the R-type hexaferrites: cation distributions and magnetic susceptibilities of MX2Fe4O11

    The strong, and heretofore unexplained, dependence of the magnetic properties of the R-type hexaferrites MX2Fe4O11 on heat treatment has been investigated by means of 57Fe and 119Sn Moessbauer spectroscopy at 297 K. 57Fe Moessbauer spectra of samples of BaTi2Fe4O11, BaSn2Fe4O11, and SrSn2Fe4O11 annealed at several temperatures consist of three partially resolved quadrupole doublet patterns. The pattern with the very large quadrupole splitting, i.e. 1.3 mm s-1 ≤ ΔEQ ≤ 1.7 mm s-1, is readily assigned to the trigonal bipyramidal site, and exhibits no dependence of its parameters, including the relative intensity, on heat treatment. The remaining two patterns are assigned to Fe3+ ions on octahedral sites, and exhibit relative intensities that are strongly dependent on heat treatment. The 119Sn spectrum of BaSn2Fe4O11 is a broad, apparently single line that, with the exception of verifying the presence of tin as Sn4+, provides little insight into the details of the structure. The distributions of the cations over all the lattice sites have been deduced from the Moessbauer spectra and compared with the magnetic susceptibility data. It is concluded that the cation distributions of the Sn-containing phase are not strongly dependent on heat treatment, and the magnetic properties exhibit a similar insensitivity to heat treatment. The Ti analogs exhibit a strong dependence of cation distribution on heat treatment, which is reflected in widely varying magnetic ordering temperatures, a variation that is confirmed by the incipient magnetic hyperfine splitting despite the strong magnetic frustration in the R-type hexaferrites. (orig.)

  9. 聚脲润滑脂稠化剂结构与其性能的关系%The Relationships of Thickener Structures and Properties of Polyurea Grease

    赵改青; 张遂心; 王晓波; 刘维民

    2012-01-01

    以脂肪胺、芳香胺、脂环胺的不同组合和异氰酸酯为稠化剂,在不同的工艺条件下制备一系列的聚脲润滑脂;利用扫描电子显微镜(SEM)对润滑脂皂纤维微观结构进行表征;探讨不同的稠化剂组成、不同制备工艺对聚脲润滑脂的微观结构和性能的影响.结果表明:单纯均匀颗粒状稠化剂比纤维与颗粒状复合的稠化剂所制备的聚脲脂具有更优的性能;纤维结构以单根形式存在为主的聚脲润滑脂性能优于纤维结构为多根纤维聚集为一股,各股之间交织的聚脲润滑脂.%Using aliphatic amines, aromatic amines and alicyclic amines in different combinations and isocyanate as thickeners, a series of polyurea greases were prepared with different process conditions. The soap fiber microstructure of the grease was characterized by using scanning electron microscopy (SEM). The effects of different thickener composition and the preparation process on microstructure and properties of the polyurea grease were researched. The results show that polyurea grease with simple uniformly granular thickeners has better performance than that with fiber and paniculate composite thickeners. Polyurea grease with fibrous structure mainly in the form of single fiber is superior to that with fiber structure in the form of the aggregated bunch of fibers interwoven between each other.

  10. Molecular Structure - Optical Property Relationships for a Series of Non-Centrosymmetric Two-photon Absorbing Push-Pull Triarylamine Molecules

    Vivas, Marcelo G.; Silva, Daniel L.; Malinge, Jérémy; Boujtita, Mohammed; Zaleśny, Robert; Bartkowiak, Wojciech; Ågren, Hans; Canuto, Sylvio; de Boni, Leonardo; Ishow, Eléna; Mendonca, Cleber R.

    2014-03-01

    This article reports on a comprehensive study of the two-photon absorption (2PA) properties of six novel push-pull octupolar triarylamine compounds as a function of the nature of the electron-withdrawing groups. These compounds present an octupolar structure consisting of a triarylamine core bearing two 3,3'-bis(trifluoromethyl)phenyl arms and a third group with varying electron-withdrawing strength (H NO2 cross-sections, measured by using the femtosecond open-aperture Z-scan technique, showed significant enhancement from 45 up to 125 GM for the lowest energy band and from 95 up to 270 GM for the highest energy band. The results were elucidated based on the large changes in the transition and permanent dipole moments and in terms of (i) EWG strength, (ii) degree of donor-acceptor charge transfer and (iii) electronic coupling between the arms. The 2PA results were eventually supported and confronted with theoretical DFT calculations of the two-photon transition oscillator strengths.

  11. Structural Relationships and Vasorelaxant Activity of Monoterpenes

    Cardoso Lima Tamires; Mota Marcelo; Barbosa-Filho José; Viana Dos Santos Márcio; De Sousa Damião

    2012-01-01

    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 phen...

  12. Properties of fast solitary structures

    R. E. Ergun

    1999-01-01

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

  13. Structure-activity relationship of anthelmintic cyclooctadepsipeptides.

    Ohyama, Makoto; Okada, Yumiko; Takahashi, Masaaki; Sakanaka, Osamu; Matsumoto, Maki; Atsumi, Kunio

    2011-01-01

    The relationship between cyclooctadepsipeptides and their anthelmintic efficacy was examined by converting the natural products, PF1022A, PF1022E and PF1022H. Some analogues substituted at the para position of the phenyllactate moiety showed higher or equivalent activity against the parasitic nematode, Ascaridia galli in chicken when compared with the parent compounds. It is suggested that lipophilicity and the polar surface area, in addition to structural requirements of the derivatives, influenced the anthelmintic efficacy in vivo. PMID:21737929

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

    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.

  15. The structural properties of sustainable, continuous change

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

    2013-01-01

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

  16. Effect of structural alteration on the macromolecular properties of brown and bituminous coals, quantitative relationships to the hydrogenation reactivity with tetralin

    Kuznetsov, P.N.; Kuznetsova, L.I. [Inst. of Chemistry and Chemico-Metallurgical Processes, Krasnoyarsk (Russian Federation); Bimer, J.; Salbut, P.D. [Inst. of Organic Chemistry, Warszawa (Poland); Gruber, R. [Univ. de Metz (France)

    1996-12-31

    The mobility of macromolecular network has been found to be the fundamental property of both brown and bituminous coals governing the reactivity for hydrogenation with tetralin. In Kansk-Achinsk brown coal, this was primarily affected by carboxylate cross-linking via polyvalent cations like Ca.

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

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

    2016-05-01

    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

  18. 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

    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

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

    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.

  20. Structural and functional properties of designed globins

    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.

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

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

    2015-05-01

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

  2. Silver Matrix Composites - Structure and Properties

    Wieczorek J.

    2016-03-01

    Full Text Available Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting technology, followed by plastic work (the KOBO method. The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

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

    Yong-Chul Jeong

    2015-02-01

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

  4. Antibacterial barbituric acid analogues inspired from natural 3-acyltetramic acids; synthesis, tautomerism and structure and physicochemical property-antibacterial activity relationships.

    Jeong, Yong-Chul; Moloney, Mark G

    2015-01-01

    The synthesis, tautomerism and antibacterial activity of novel barbiturates is reported. In particular, 3-acyl and 3-carboxamidobarbiturates exhibited antibacterial activity, against susceptible and some resistant Gram-positive strains of particular interest is that these systems possess amenable molecular weight, rotatable bonds and number of proton-donors/acceptors for drug design as well as less lipophilic character, with physicochemical properties and ionic states that are similar to current antibiotic agents for oral and injectable use. Unfortunately, the reduction of plasma protein affinity by the barbituric core is not sufficient to achieve activity in vivo. Further optimization to reduce plasma protein affinity and/or elevate antibiotic potency is therefore required, but we believe that these systems offer unusual opportunities for antibiotic drug discovery. PMID:25710842

  5. Structural relationships and vasorelaxant activity of monoterpenes

    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.

  6. Structure-cytotoxicity relationships for dietary flavonoids

    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...

  7. Familial identification: population structure and relationship distinguishability.

    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.

  8. Familial Identification: Population Structure and Relationship Distinguishability

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

    2012-01-01

    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. PMID:22346758

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

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

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

    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

  11. Some Structural Properties of SAT

    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.

  12. Structural Relationships and Vasorelaxant Activity of Monoterpenes

    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.

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

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

    2012-03-15

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

  14. Features of Managers’ Personality Psychological Properties Relationship

    Guzel Shaukatovna Gabdreeva; Alisa Ramilevna Khalfieva

    2014-01-01

    The aim of this article is researching psychological characteristics of Manager’s personality. The leadingapproach of this research is to show close relationship of gender characteristics and significant features ofManagers’ personality. It has been shown that the most characteristic qualities of effective managers arecommunication skills, strong-willed qualities and also abilities to self-setting goals and organization of actionsaimed at achieving them. Basic contributors indicating personal...

  15. 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

    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.

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

    Preciado, Victor M; Verghese, George C

    2011-01-01

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

  17. Quasicrystals Structure and Physical Properties

    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

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

    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.

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

    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.

  20. Structure/function relationships in cellulolytic enzymes

    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.

  1. Structure-property relationships in radical-cation (electron-donor molecule) and anion-based (including fullerides) organic superconductors and their use in the design of new materials

    Williams, J.M.; Carlson, K.D.; Kini, A.M. [Argonne National Lab., IL (United States)

    1993-08-01

    The presently known structure-property relations that have been developed for organic superconductors based on the ET molecule (b- phases and k-phases), and the C{sub 60}-anion-based fullerides, and their use in the structural design of new superconducting materials are discussed. 12 refs, 11 figs, 4 tabs.

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

    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.

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

    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

  4. Structure-composition relationships and optical properties in cerium-substituted (Sr,Ba)3(Y,La)(BO3)3 borate phosphors

    Denault, Kristin A.; Cheng, Zhiyuan; Brgoch, Jakoah; DenBaars, Steven P.; Seshadri, Ram [UCSB

    2013-12-04

    Relationships between the structure and composition, and their influence on the optical properties, of a family of cerium-substituted borate compounds with formula A3RE(BO3)3 (A = Ba, Sr; RE = Y, La) are studied using a combination of high resolution synchrotron X-ray powder diffraction and photoluminescence. Examination of the coordination environment of the Ce3+ active site polyhedra coupled with photoluminescence at 77 K reveal three distinct excitation bands corresponding to Ce3+ located on three distinct crystallographic sites. Comparing the position of these excitation bands with crystal field splitting effects due to changes in polyhedral volumes and distortions suggest an assignment of the three excitation bands. These compounds are efficiently excited by UV light (≈340 nm) with blue emission at a maximum wavelength of 413 nm for Ba3Y(BO3)3:Ce3+,Na+, 422 nm for Sr3Y(BO3)3:Ce3+,Na+, and 440 nm for Sr3La(BO3)3:Ce3+,Na+. The most efficient compound was determined to be Sr3La(BO3)3:Ce3+,Na+ with a quantum yield of 50%.

  5. Mereology of Quantitative Structure-Activity Relationships Models

    Guillermo Restrepo

    2015-12-01

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

  6. Relationship of quantitative structure and pharmacokinetics in fluoroquinolone antibacterials

    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.

  7. Relationship between protein structure and geometrical constraints

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

    1996-01-01

    We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures...... using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the 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...

  8. Relationship between protein structure and geometrical constrains

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

    1996-01-01

    We evaluate to what extent the structure of proteins can be deduced from incomplete knowledge of disulfide bridges, surface assignments, secondary structure assignments, and additional distance constraints. A cost function taking such constraints into account was used to obtain protein structures...... using a simple minimization algorithm. For small proteins, the approximate structure could be obtained using one additional distance constraint for each amino acid in the protein. We also studied the 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...

  9. Cross-scale method for quantitative structure-property relationship of drug-loaded polymeric micelles%跨尺度方法研究聚合物载药胶束的定量构性关系

    吴文胜; 张灿阳; 李秀喜; 徐骁; 钱宇; 章莉娟

    2015-01-01

    Taking drug-loaded micelles self-assembled from the amphiphilic polymers as a case, the quantitative structure-property relationship (QSPR) of chemical products was studied on the basis of the cross-scale method from macroscopic to microscopic in this work. A block unit autocorrelation method to calculate the descriptors for characterization of amphiphilic polymer structure was proposed. A series of QSPR models to predict the drug-loading capacity of polymeric micelles at different drug/polymer ratios were established by combining genetic function approximation (GFA) algorithm and multiple linear regression (MLR). The reliability, stability and predictive ability of models were evaluated via internal validation (R2>0.854, Qloo-cv>0.651, RMSE0.629) as well as application domain definition analysis. The effect of blocks and topological structure of polymers on drug-loading capacity was well explained by descriptors and drug-loaded mechanism analysis. The QSPR models were hopefully used to provide a guide for new polymer design and drug-loading capacity prediction. Also this cross-scale method would be expected to promote the design and development of novel complex structured products.%以两亲性聚合物自组装载药胶束为案例,基于宏观到微观的跨尺度方法研究化学产品的定量构性关系(QSPR),提出嵌段单元自相关方法计算表征两亲性聚合物结构的描述符,结合遗传函数算法和多元线性回归建立了不同药物/聚合物配比下聚合物胶束载药量的 QSPR 预测模型,经内部验证(R2>0.854,Q2loo-cv>0.651, RMSE0.629),以及应用域定义分析评估了模型的可靠性、稳定性和预测能力。通过对描述符的分析和载药机制解释,很好地阐释了聚合物嵌段单元和聚合物拓扑结构对胶束载药量的影响。QSPR 模型的建立将指导新聚合物及其载药胶束体系的设计,并预测其载药能力,这种跨尺度研究方法有望促进

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

    Bethany Percha

    2015-07-01

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

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

    Percha, Bethany; Altman, Russ B

    2015-07-01

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

  12. Structural and dynamical properties of Yukawa balls

    To study the structural and dynamical properties of finite 3D dust clouds (Yukawa balls) new diagnostic tools have been developed. This contribution describes the progress towards 3D diagnostics for measuring the particle positions. It is shown that these diagnostics are capable of investigating the structural and dynamical properties of Yukawa balls and gaining insight into their basic construction principles

  13. The Effect of Bedding Structure on Mechanical Property of Coal

    Zetian Zhang

    2014-01-01

    Full Text Available The mechanical property of coal, influencing mining activity considerably, is significantly determined by the natural fracture distributed within coal mass. In order to study the effecting mechanism of bedding structure on mechanical property of coal, a series of uniaxial compression tests and mesoscopic tests have been conducted. The experimental results show that the distribution characteristic of calcite particles, which significantly influences the growth of cracks and the macroscopic mechanical properties of coal, is obviously affected by the bedding structure. Specifically, the uniaxial compression strength of coal sample is mainly controlled by bedding structure, and the average peak stress of specimens with axes perpendicular to the bedding planes is 20.00 MPa, which is 2.88 times the average amount of parallel ones. The test results also show a close relationship between the bedding structure and the whole deformation process under uniaxial loading.

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

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

    2012-04-01

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

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

    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

  16. Investigation of structure-properties relationship in a novel family of halogenoantimonates(III) and halogenobismuthates(III) with morpholinium cation: [NH2(C2H4)2O]MX4. Crystal structure, phase transitions and dynamics of molecules.

    Owczarek, Magdalena; Jakubas, Ryszard; Pietraszko, Adam; Medycki, Wojciech; Baran, Jan

    2013-11-14

    Three new organic-inorganic hybrids based on halogenoantimonates(III) and halogenobismuthates(III) with the morpholinium cation, [NH2(C2H4)2O]SbCl4, [NH2(C2H4)2O]SbBr4 and [NH2(C2H4)2O]BiBr4, have been prepared and characterized with DSC, TGA, DTA and single-crystal X-ray diffraction. The common feature of the crystal structures of the studied compounds is the presence of polyanionic ([MX4]∞(-)) and morpholinium (head-to-tail configuration) chains, which expand themselves parallel to each other. The antimonate derivatives are isomorphous, crystallizing in a centrosymmetric orthorhombic Pbca space group and show no phase transitions (PTs) between 110 and 370 K. On the other hand, [NH2(C2H4)2O]BiBr4 undergoes two first-order structural PTs: I ↔ II at 321/343 K (cooling/heating) and II ↔ III at 285/289 K (cooling/heating). The mechanism of the PTs is discussed on the basis of crystallographic data and (1)H NMR and infrared spectroscopy. The PT at 343 K is accompanied by a spectacular switching of the spin-lattice T1 relaxation pathway. Structural parameters analysis has been performed to discuss a structure-properties relationship. PMID:23999763

  17. Structural Join and Staircase Join Algorithms of Sibling Relationship

    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. Analyzing the sequence-structure relationship of a library of local structural prototypes.

    Benros, Cristina; de Brevern, Alexandre G; Hazout, Serge

    2009-01-21

    We present a thorough analysis of the relation between amino acid sequence and local three-dimensional structure in proteins. A library of overlapping local structural prototypes was built using an unsupervised clustering approach called "hybrid protein model" (HPM). The HPM carries out a multiple structural alignment of local folds from a non-redundant protein structure databank encoded into a structural alphabet composed of 16 protein blocks (PBs). Following previous research focusing on the HPM protocol, we have considered gaps in the local structure prototype. This methodology allows to have variable length fragments. Hence, 120 local structure prototypes were obtained. Twenty-five percent of the protein fragments learnt by HPM had gaps. An investigation of tight turns suggested that they are mainly derived from three PB series with precise locations in the HPM. The amino acid information content of the whole conformational classes was tackled by multivariate methods, e.g., canonical correlation analysis. It points out the presence of seven amino acid equivalence classes showing high propensities for preferential local structures. In the same way, definition of "contrast factors" based on sequence-structure properties underline the specificity of certain structural prototypes, e.g., the dependence of Gly or Asn-rich turns to a limited number of PBs, or, the opposition between Pro-rich coils to those enriched in Ser, Thr, Asn and Glu. These results are so useful to analyze the sequence-structure relationships, but could also be used to improve fragment-based method for protein structure prediction from sequence. PMID:18977232

  19. The Relationship Communication Structure - Uncertainty Avoidance

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

    Warokka, Ari; Herrera, Juan Jose Duran

    2011-01-01

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

  1. Relaxation, Structure, and Properties of Semicoherent Interfaces

    Shao, S.; Wang, J.

    2016-01-01

    Materials containing a high density of interfaces are promising candidates for future energy technologies because interfaces acting as sources, sinks, and barriers for defects can improve mechanical and irradiation properties of materials. A semicoherent interface widely occurring in various materials is composed of a network of misfit dislocations and coherent regions separated by misfit dislocations. In this article, we review the relaxation mechanisms, structure, and properties of (111) semicoherent interfaces in face-centered cubic structures.

  2. Structure and properties of carbon nanotubes

    MEYER, Jannik

    2006-01-01

    The properties of nanoscopic objects depend critically on the position of each atom, since finite-size and quantization effects play an important role. For carbon nanotubes, the electronic, mechanical, and vibrational properties vary significantly depending on their structure. For example, a carbon nanotube can be metallic or semiconducting with varying band-gaps depending on its lattice structure. Yet, most investigations on individual carbon nanotubes are carried out on objects with unknown...

  3. Electrical and structural properties of strontium orthovanadate

    Electrical and structural properties of strontium orthovanadate in the range 600-1200 deg C have been studied. Electric properties of Sr3(VO4)2 are conditioned by vacancies in sublattices of oxygen and strontium, temperature changes in the structure -by competing processes of vacancy (oxygen and strontium ions) and internodal (strontium ions) disordering. The effect of point defects in Sr3(VO4)2 on the position of optical absorption band edge is discussed

  4. Interfacial structure, properties and design

    These proceedings are organized in the order of presentation at the meeting, starting with the recent advances in structural characterization and analysis of internal interface and interphase boundaries. While the crystallographic theory of interfacial line defects had been established rigorously, its general applicability to mixed tilt and twist boundaries was questioned. The insights obtained from theoretical and experimental analyses of elasticity and localized deformation at interfaces relate directly to the intrinsic cohesive strength and intergranular fracture. Effects of processing on the grain boundary structure and chemistry of high Tc ceramic superconductors and the resulting changes in critical currents were established experimentally. A significant advancement was reported in processing and crystal growth techniques, which include the UHV diffusion bonding and MBE techniques for the controlled production of homo- and heterophase interfaces

  5. Structural properties of close II$_1$ factors

    Cameron, Jan; Christensen, Erik; Sinclair, Allan M.; Smith, Roger R.; White, Stuart; Wiggins, Alan D.

    2016-01-01

    We show that a number of key structural properties transfer between sufficiently close II$_1$ factors, including solidity, strong solidity, uniqueness of Cartan masas and property $\\Gamma$. We also examine II$_1$ factors close to tensor product factors, showing that such factors also factorise as a tensor product in a fashion close to the original.

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

    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.

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

    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…

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

    Krzyńska A.; Kaczorowaki M.

    2007-01-01

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

  9. Structure and properties of metals

    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...

  10. Structure-activity relationships of bumetanide derivatives

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

    2015-01-01

    and its derivatives in dogs and their inhibition of hNKCC2A (r(2) = 0.817; P < 0.01). Replacement of the carboxylic group of bumetanide by a non-ionic residue, for example, an anilinomethyl group, decreased inhibition of hNKCC2A, indicating that an acidic group was required for transporter inhibition...... 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......, the effect of a series of diuretically active bumetanide derivatives was investigated on human NKCC2 variant A (hNKCC2A) expressed in Xenopus laevis oocytes. KEY RESULTS: Bumetanide blocked hNKCC2A transport with an IC50 of 4 μM. There was good correlation between the diuretic potency of bumetanide...

  11. Structure of Csm2 elucidates the relationship between small subunits of CRISPR-Cas effector complexes.

    Venclovas, Česlovas

    2016-05-01

    Type I and type III CRISPR-Cas effector complexes share similar architecture and have homologous key subunits. However, the relationship between the so-called small subunits of these complexes remains a contentious issue. Here, it is shown that the recently solved structure of Thermotoga maritima Csm2 represents a dimer with the extensive structure swapping between monomers. Unswapping the structure generates a compact globular monomer which shares similar structure and surface properties with Cmr5, the small subunit of a related Cmr complex. Detailed analysis of available structures of small subunits reveals that they all have a common fold suggesting their common origin. PMID:27091242

  12. Relationships between physical properties and sequence in silkworm silks

    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.

  13. The structural acoustic properties of stiffened shells

    Luan, Yu

    2008-01-01

    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....

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

    Starling David Hunter

    2015-01-01

    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 re...

  15. Autoclave foam concrete: Structure and properties

    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.

  16. A New Structural Property of SAT

    Di Zenzo, Silvano

    2008-01-01

    We review a minimum set of notions from our previous paper on structural properties of SAT at arXiv:0802.1790 that will allow us to define and discuss the "complete internal independence" of a decision problem. This property is strictly stronger than the independence property that was called "strong internal independence" in cited paper. We show that SAT exhibits this property. We argue that this form of independence of a decision problem is the strongest possible for a problem. By relying up...

  17. STRUCTURAL AND THERMOPHYSICAL PROPERTIES OF HARDENING CONCRETE

    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.

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

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

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

    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…

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

    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.

  1. Data base on structural materials aging properties

    Oland, C.B.

    1992-03-01

    The US Nuclear Regulatory Commission has initiated a Structural Aging Program at the Oak Ridge National Laboratory to identify potential structural safety issues related to continued service of nuclear power plants and to establish criteria for evaluating and resolving these issues. One of the tasks in this program focuses on the establishment of a Structural Materials Information Center where long-term and environment-dependent properties of concretes and other structural materials are being collected and assembled into a data base. These properties will be used to evaluate the current condition of critical structural components in nuclear power plants and to estimate the future performance of these materials during the continued service period.

  2. Structure and properties of textile reinforced concrete

    Volkova, A.A.; A.V. Paykov; O.N. Stolyarov; S.G. Semenov; B.E. Melnikov

    2015-01-01

    In this paper the structure and properties of textile-reinforced concrete were investigated. Two types of high strength reinforcing fabrics made of glass and carbon rovings were used in this study. The samples of textile-reinforced concrete were produced. The mechanical properties of the developed samples were determined via a three-point bending test. The maximum flexural strength and reinforcement efficiency were calculated. It was found that the samples with textile reinforcement have high...

  3. Structural properties of the Hugoniot curve

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

  4. Electronic structure and magnetic properties of actinides

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

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

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

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

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

  7. Structure activity relationship of selective GABA uptake inhibitors

    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 in the...

  8. Relationships of Selected Factors to Summer Session Organizational Structure.

    Young, Raymond J.; McDougall, William P.

    Patterns of organization for summer schools were examined for 55 American and seven Canadian public four-year colleges and universities, including research universities, doctorate-granting universities, and comprehensive universities and colleges. Relationships between organizational structure and the following factors were assessed: institutional…

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

    Wagner, John Robert

    1987-01-01

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

  10. Relationship of coal reservoir thickness and its permeability and gas-bearing property

    Qin, Y.; Ye, J.; Lin, D.; Jiao, S.; Li, G. [China University of Mining and Technology (China)

    2000-02-01

    The permeability and gas-bearing property of coal reservoir are remarkably affected by its thickness. Research has shown that in North China the relationship between the thickness of the coal reservoirs and their permeability is distinctly distributed in two regions. The structurally destroyed coal reservoirs is tended to be negatively related to the borehole permeability. In the coal reservoirs with completely-original structure, the relationship between its thickness and the borehole permeability appears to have a permeability threshold value of 0.5 mD. The coalbed methane content in some areas of China increases with increasing thickness. The threshold permeability of the commercially valuable coal reservoirs in China should be around 0.5 mD. 12 refs., 2 figs., 1 tab.

  11. Property and capital structure of the enterprise

    PLÁTOVÁ, Lenka

    2013-01-01

    This bachelor thesis analyses as the financial and capital structure of the specific company in its particular context so the level of managament of this company situated in Jihlava. The first part focuses on the general characteristics of the property and capital of the company and it also includes the methods and indicators that are used in the practical part. The thesis starts with the brief introduction of the company and then it mentions its analysis of the financial and capital structure.

  12. DOES ORGANIZATION STRUCTURE MATTER? ON THE RELATIONSHIP BETWEEN THE STRUCTURE, FUNCTIONING AND EFFECTIVENESS

    JON AARUM ANDERSEN; PATRIK JONSSON

    2006-01-01

    Managers often see new organizational design as the solution to many problems. This paper explores the relationship between organization structure (design), functioning of organizations, and effectiveness. A study of 320 companies showed that the structural variable, decentralization, marginally affected the way in which organizations function. Functional variables had a minor impact on profitability. No direct relationship between structure and effectiveness was found. When functioning is co...

  13. Property segment and REIT capital structure

    M. Ertugrul; E. Giambona

    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,

  14. Structure, chemistry, and properties of mineral nanoparticles

    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.

  15. Molecular Structures and Functional Relationships in Clostridial Neurotoxins

    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.

  16. A New Structural Property of SAT

    Di Zenzo, Silvano

    2008-01-01

    We review a minimum set of notions from our previous paper on structural properties of SAT at arXiv:0802.1790 that will allow us to define and discuss the "complete internal independence" of a decision problem. This property is strictly stronger than the independence property that was called "strong internal independence" in cited paper. We show that SAT exhibits this property. We argue that this form of independence of a decision problem is the strongest possible for a problem. By relying upon this maximally strong form of internal independence, we reformulate in more strict terms the informal remarks on possible exponentiality of SAT that concluded our previous paper. The net result of that reformulation is a hint for a proof for SAT being exponential. We conjecture that a complete proof of that proposition can be obtained by strictly following the line of given hint of proof.

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

    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 η-phase and α-Al solid solution with Zn dissolved into the matrix. The silver concentration in AlZn alloy influences the volume of AgZn3 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.

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

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

  19. Critical analysis of carcinogenicity study outcomes. Relationship with pharmacological properties.

    van der Laan, Jan Willem; Kasper, Peter; Silva Lima, Beatriz; Jones, David R; Pasanen, Markku

    2016-08-01

    Predicting the outcome of life-time carcinogenicity studies in rats based on chronic (6-month) toxicity studies in this species is possible in some instances. This should reduce the number of such studies and hence have a significant impact on the total number of animals used in safety assessment of new medicines. From a regulatory perspective, this should be sufficient to grant a waiver for a carcinogenicity study in those cases where there is confidence in the outcome of the prediction. Pharmacological properties are a frequent key factor for the carcinogenic mode of action of some pharmaceuticals, but data-analysis on a large dataset has never been formally conducted. We have conducted an analysis of a dataset based on the perspective of the pharmacology of 255 compounds from industrial and regulatory sources. It is proposed that a pharmacological, class-specific, model may consist of an overall causal relationship between the pharmacological class and the histopathology findings in rats after 6 months treatment, leading to carcinogenicity outcome after 2 years. Knowledge of the intended drug target and pathway pharmacology should enhance the prediction of either positive or negative outcomes of rat carcinogenicity studies. The goal of this analysis is to review the pharmacological properties of compounds together with the histopathology findings from the chronic toxicity study in rodents in order to introduce an integrated approach to estimate the risk of human carcinogenicity of pharmaceuticals. This approach would allow scientists to define conditions under which 2-year rat carcinogenicity studies will or will not add value to such an assessment. We have demonstrated the possibility of a regulatory waiver for a carcinogenicity study in rats, as currently discussed in the International Council for Harmonization (ICH) - formerly known as the International Conference on Harmonization (ICH), by applying the proposed prediction approach in a number of case studies

  20. Structural properties of small rhodium clusters

    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.

  1. Structural properties of small rhodium clusters

    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

  2. Psychometric properties of the Polish adaptation of the Adult Sibling Relationship Questionnaire (ASRQ

    Wałęcka-Matyja, Katarzyna

    2014-12-01

    Full Text Available Background. Polish studies have not been focused on the method enabling a reliable and valid measure of the psychological attributes of sibling relationships in the period of adulthood. Aim. The aim of this study was to determine the psychometric properties of the Polish adaptation of the Adult Sibling Relationship Questionnaire (ASRQ. Methods. The study included 406 students of different majors of the University of Łódź and the Łódź University of Technology. In the surveyed group, 58.9% were women (n=239 and 41.1% men (n=167. The participants of the survey were adult, aged from 18 to 35 years (M=23.7,SD=3,891. Results. The three main ASRQ factors (Warmth, Conflict, Rivalry showed good internal consistency (Cronbach’s α .87-.97. Correlations between the individual scales creating the main factors demonstrate similar patterns to the results obtained by the authors of the original version of the ASRQ. The results of the conducted exploratory (EFA and confirmatory (CFA factor analyses confirm the factorial structure of the original version of the ASRQ. Discussion. The presented results indicate that the ASRQ in the Polish adaptation is a reliable and valid multidimensional measure of relationships between siblings in early adulthood. Conclusions. The Polish adaptation of the Adult Sibling Relationship Questionnaire can open an era of the researchers’ interest in the subject area of relationships between siblings in the period of adulthood.

  3. Nucleon structure and properties of dense matter

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

  4. Structuring strategy and relationships in North American gas markets

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

  5. Bank Image Structure: The Relationship to Consumer Behaviour

    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.

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

    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.

  7. Dissecting the two models of TCR structure-function relationships.

    Cohn, Melvin

    2016-08-01

    There are only two comprehensive models attempting to account for the TCR structure-function relationships, referred to as the Standard or Centric model (Model I) and the Tritope model (Model II). This essay is written to analyze comparatively the two formulations of restrictive reactivity, stressing in particular the logic of each. Model I is essentially built on an analogy between the TCR and the BCR. Given a TCR with only one combining site (paratope), restrictive recognition requires that its ligand be viewed as a composite structure between the peptide and restricting element. It is this relationship that entrains a set of correlates that makes Model I untenable. Model II is predicated on the postulate that the recognition of the allele-specific determinants expressed by MHC-encoded restricting elements (R) is germline encoded and selected, whereas the recognition of peptide (P) is somatically encoded and selected. These selective pressures must operate on definable structures and this, in turn, necessitates a multiply recognitive T cell antigen receptor (TCR) with independent anti-R and anti-P paratopes that function coherently to signal restrictive reactivity. The consequences of this "two repertoire" postulate give us a concept of TCR structure quite distinct from that at present generally accepted, as well as a surprising relationship between numbers of functional TCR V gene segments and allele-specific determinants in the species. In the end, both models must deal with the relationship between the epitope-paratope interaction(s) and the signals to the T cell necessary for its differentiation and function. PMID:27114367

  8. Structural equation analyses of personality, appraisals, and coping relationships

    Kulenović, Alija; Buško, Vesna

    2007-01-01

    The study deals with the hypothesized mediating effects of cognitive appraisals on stressfulness of the event in the personality, stress, and coping processes. The relationships between personality measured by NEO-FFI questionnaire, perceived stressfulness of the event, and situation-specific coping measures, were analyzed in a prospective framework with 421 basic military trainees. Analyses of linear structural models partially supported the hypotheses of Lazarus transactional theory on the ...

  9. Structure-activity relationship of crustacean peptide hormones.

    Katayama, Hidekazu

    2016-04-01

    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. PMID:26624010

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

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

    2016-07-01

    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 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. PMID:27112573

  11. Structure-activity relationship of indoloquinoline analogs anti-MRSA.

    Zhao, Min; Kamada, Tomonori; Takeuchi, Aya; Nishioka, Hiromi; Kuroda, Teruo; Takeuchi, Yasuo

    2015-12-01

    Indolo[3,2-b]quinoline analogs (3a-3s), 4-(acridin-9-ylamino) phenol hydrochloride (4), benzofuro[3,2-b]quinoline (3t), indeno[1,2-b]quinolines (3u and 3v) have been synthesized. Those compounds were found to exhibit anti-bacterial activity towards Methicillin-resistant Staphylococcus aureus (anti-MRSA activity). Structure-activity relationship studies were conducted that indoloquinoline ring, benzofuroquinoline ring and 4-aminophenol group are essential structure for anti-MRSA activity. PMID:26522949

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

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

  13. Thermal and structural properties of ionic fluids.

    Bartsch, Hendrik; Dannenmann, Oliver; Bier, Markus

    2015-04-01

    The electrostatic interaction in ionic fluids is well known to give rise to a characteristic phase behavior and structure. Sometimes its long range is proposed to single out the electrostatic potential over other interactions with shorter ranges. Here the importance of the range for the phase behavior and the structure of ionic fluids is investigated by means of grandcanonical Monte Carlo simulations of the lattice restricted primitive model (LRPM). The long-ranged electrostatic interaction is compared to various types of short-ranged potentials obtained by sharp and/or smooth cutoff schemes. Sharply cutoff electrostatic potentials are found to lead to a strong dependence of the phase behavior and the structure on the cutoff radius. However, when combined with a suitable additional smooth cutoff, the short-ranged LRPM is found to exhibit quantitatively the same phase behavior and structure as the conventional long-ranged LRPM. Moreover, the Stillinger-Lovett perfect screening property, which is well known to be generated by the long-ranged electrostatic potential, is also fulfilled by short-ranged LRPMs with smooth cutoffs. By showing that the characteristic phase behavior and structure of ionic fluids can also be found in systems with short-ranged potentials, one can conclude that the decisive property of the electrostatic potential in ionic fluids is not the long range but rather the valency dependence. PMID:25974477

  14. Structure and Frictional Properties of Colloid Gel

    Masayuki Tokita

    2014-03-01

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

  15. Acoustical properties of nonwoven fiber network structures

    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

  16. Structure and properties of carbon fiber sorbents

    Adsorption properties of fiber carbon materials, differing in initial raw material, preparation process, final treatment temperature, i. e. the factors responsible for the fiber structure, were studied. Conditions of surface activation, like oxidant nature, gas feed rate, oxidation temperature and duration were varied in a wide range of values to prepare adsorbents featuring prescribed parameters of porous structure. One type of carbon fiber was chosen and activation conditions, permitting development of the initial surface from 0.5 to 2000 m2/g without any loss of mechanical strength, were selected for it

  17. Structural and tunneling properties of Si nanowires

    Montes, E.

    2013-12-06

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

  18. Structure and properties of textile reinforced concrete

    A.A. Volkova

    2015-11-01

    Full Text Available In this paper the structure and properties of textile-reinforced concrete were investigated. Two types of high strength reinforcing fabrics made of glass and carbon rovings were used in this study. The samples of textile-reinforced concrete were produced. The mechanical properties of the developed samples were determined via a three-point bending test. The maximum flexural strength and reinforcement efficiency were calculated. It was found that the samples with textile reinforcement have higher strength characteristics as compared to nonreinforced concrete. Furthermore, the deformation behavior of reinforced concrete was analyzed. The advantage is in higher residual load-bearing capacity, which allows maintaining the integrity of the structure.

  19. Structure Analysis and Properties of Unleaded Brasses

    Rzadkosz S.

    2015-04-01

    Full Text Available The analysis of brasses regarding their microstructure, mechanical properties and ecological characteristics has been presented. The influence of characteristic alloying elements contained in the brasses and the possibilities of replacing them with other elements have been assessed. The paper contains the results of studies on the influence of chosen additional elements shaping the structure and properties of unleaded alloys based on Cu-Zn system as the matrix. The research aimed at determining the mechanism and the intensity of influence of such additives as tellurium and bismuth. The microstructures were investigated with the help of light microscopy and scanning electron microscopy with X-ray microanalysis (SEM-EDS for determining significant changes of the properties.

  20. Relationship between Crustal Structure and Tin Mineralization in South China

    1999-01-01

    A close relationship between tin metallogenic and crustal structure in South China is demonstrated, which is based on a careful study on crustal structure and a detailed comparison between typical deposits in different tectonic units. Types, locations, emplacement of ore bodies and ore genesis of tin deposits are relative to crustal structure. Tin mineralization zones of South China can be divided into three tin metallogenic units including the west part corresponding to Youjiang fold belt, middle part corresponding to fold belt of Hunan-Guangdong-Jiangxi provinces and the east part corresponding to Southeast China coastal volcanic faulting depression. From the above, it is concluded that crustal compositions and structures are the main facts of Sn concentration in South China.

  1. Structural Properties of Green Tea Catechins

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

    2015-01-01

    Green tea catechins are polyphenols which are believed to provide health benefits; they are marketed as health supplements and are studied for their potential effects on a variety of medical conditions. However, their mechanisms of action and interaction with the environment at the molecular level are still not well-understood. Here, by means of atomistic simulations, we explore the structural properties of four green tea catechins, in the gas phase and water solution: specifically, (-)-epiga...

  2. Structure and Electronic Properties of Polycrystalline Dielectrics

    Mckenna, Keith P.; Shluger, AL

    2013-07-07

    We present an overview of the theoretical approaches that can be employed to model polycrystalline oxides along with a discussion of their limitations and associated challenges. We then present results for two metal oxide materials, MgO and HfO2, where theory and experiment have come together to provide insight into the structure and electronic properties of grain boundaries. Finally, we conclude with a discussion and outlook.

  3. Effective structural properties in polycrystalline graphene

    Hossain, Zubaer

    This talk will discuss effective structural properties in polycrystalline graphene under the presence of atomic scale heterogeneity. Polycrystallinity is ubiquitous in solids, but theories describing their effective behavior remain limited, particularly when heterogeneity is present in the form of nonuniform deformation or composition. Over the decades, exploration of the effective transport and strength properties of heterogeneous systems has been carried out mostly with random distribution of grains or regular periodic structures under various approximations, in translating the underlying physics into a single representative volume element. Although heterogeneity can play a critical role in modulating the basic behavior of low-dimensional materials, it is difficult to capture the local characteristics accurately by these approximations. Taking polycrystalline graphene as an example material, we study the effective structural properties (such as Young's Modulus, Poisson's ratio and Toughness) by using a combination of density functional theory and molecular dynamic simulations. We identify the key mechanisms that govern their effective behavior and exploit the understanding to engineer the behavior by doping with a carefully selected choice of chemical elements.

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

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

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

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

  6. Structural characterization and pharmaceutical properties of porphyran

    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.

  7. Pyrochlores and perovskites: candidates for exploring structure functionality relationships

    Pyrochlores (A2B2O7) and perovskites (ABO3) are two widely studied classes of compounds which exhibit myriad properties like ionic conductivity, magnetism, dielectric behaviour, catalysis, optical properties etc. The stability of these structures is highly dependent upon the radius ratio of the cations occupying A- and B-sites. The intriguing crystal chemistry that originates from varying this radius ratio forms the basis for interesting structural studies. Further, the elemental versatility allows possibility of introducing a variety of guest ions in its lattice which makes it possible to fine tune the structure in order to obtain desirable properties. Some of the recent studies in our group have shown that in rare earth based mixed-pyrochlore oxides like Sm2-xDyxZr2O7, Gd1-xNdxZr2O7(0.0 ≤ x ≤ 2.0) etc., fine tuning of structure could be obtained by varying A-site cation which had a profound bearing on ionic conductivity of the resultant system. Similarly, the ABO3 systems like GdSc1-xInxO3, Gd1-xYxInO3 (0.0 ≤ x ≤ 1.0) etc. showed interesting structural and dielectric behavior due to fine control of BO5, polyhedra in these indates. The careful tuning of A and B-site occupants and the choice of synthesis route lead to stabilization of metastable structures in these classes with tunable electrical behavior. The present talk will thus concentrate upon elucidating the relation between structure and the electrical behavior by taking specific examples in these two classes of compounds. (author)

  8. Applying quantitative structure-activity relationship approaches to nanotoxicology: current status and future potential.

    Winkler, David A; Mombelli, Enrico; Pietroiusti, Antonio; Tran, Lang; Worth, Andrew; Fadeel, Bengt; McCall, Maxine J

    2013-11-01

    The potential (eco)toxicological hazard posed by engineered nanoparticles is a major scientific and societal concern since several industrial sectors (e.g. electronics, biomedicine, and cosmetics) are exploiting the innovative properties of nanostructures resulting in their large-scale production. Many consumer products contain nanomaterials and, given their complex life-cycle, it is essential to anticipate their (eco)toxicological properties in a fast and inexpensive way in order to mitigate adverse effects on human health and the environment. In this context, the application of the structure-toxicity paradigm to nanomaterials represents a promising approach. Indeed, according to this paradigm, it is possible to predict toxicological effects induced by chemicals on the basis of their structural similarity with chemicals for which toxicological endpoints have been previously measured. These structure-toxicity relationships can be quantitative or qualitative in nature and they can predict toxicological effects directly from the physicochemical properties of the entities (e.g. nanoparticles) of interest. Therefore, this approach can aid in prioritizing resources in toxicological investigations while reducing the ethical and monetary costs that are related to animal testing. The purpose of this review is to provide a summary of recent key advances in the field of QSAR modelling of nanomaterial toxicity, to identify the major gaps in research required to accelerate the use of quantitative structure-activity relationship (QSAR) methods, and to provide a roadmap for future research needed to achieve QSAR models useful for regulatory purposes. PMID:23165187

  9. Structure-activity relationship studies of citalopram derivatives

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

    2016-01-01

    . 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 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 citalopram from talopram in conferring selectivity towards the S1 and S2 site, respectively, was assessed by determining the binding of 14 citalopram/talopram analogous to the S1 and S2 binding sites in SERT using membranes of COS7 cells transiently expressing SERT. KEY RESULTS: The structure...

  10. Structure and function relationships in IgA.

    Woof, J M; Russell, M W

    2011-11-01

    Immunoglobulin A (IgA) has a critical role in immune defense particularly at the mucosal surfaces, and is equipped to do so by the unique structural attributes of its heavy chain and by its ability to polymerize. Here, we provide an overview of human IgA structure, describing the distinguishing features of the IgA1 and IgA2 subclasses and mapping the sites of interaction with host receptors important for IgA's functional repertoire. Remarkably, these same interaction sites are targeted by binding proteins and proteases produced by various pathogens as a means to subvert the protective IgA response. As interest in the prospect of therapeutic IgA-based monoclonal antibodies grows, the emerging understanding of the relationship between IgA structure and function will be invaluable for maximizing the potential of these novel reagents. PMID:21937984

  11. Hierarchial relationships among formal cognitive structures and their relationship to principled moral reasoning

    Zeidler, Dana L.

    Measurements of formal reasoning and principled moral reasoning ability were obtained from a sample of 99 tenth grade students. Specific modes of formal reasoning (proportional reasoning, controlling variables, probabilistic, correlational, and combinatorial reasoning) were first examined. Findings support the notion of hierarchical relationships which exist among those variables. Further results from factor analysis provide evidence that the variables represent specific cognitive structures that are interdependent with each other and precede operations in development. Finally, significant relationships were found to exist between the different modes of formal reasoning and principled moral reasoning. Combinatorial and correlational reasoning were found to significantly account for 22% of the variance in principled moral reasoning. Theoretical and educational implications are discussed.

  12. Prediction of GC retention times of complex petroleum fractions based on quantitative structure-retention relationships

    Moustafa, N.E. [Egyptian Petroleum Research Inst., Cairo (Egypt)

    2008-01-15

    A new quantitative structure-property relationship (QSRR) eight parameter correlation (R = 0.998) of gas chromatographic retention times for a diverse set of 35 petroleum condensate components was developed by application of multiple linear regression analysis (MLR). The descriptors are all calculated directly from the molecular structure using Dragon software. A boiling point-based model (R = 0.999) of a subset of 19 components was used as assistance. The predictive ability of both models was tested for some unknown components. The obtained model was used for interpretation of the retention behaviour of the investigated petroleum components. (orig.)

  13. Structure and magnetic properties of powder HITPERM material

    J.E. Frąckowiak

    2007-03-01

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

  14. Network-Level Structure-Function Relationships in Human Neocortex.

    Mišić, Bratislav; Betzel, Richard F; de Reus, Marcel A; van den Heuvel, Martijn P; Berman, Marc G; McIntosh, Anthony R; Sporns, Olaf

    2016-07-01

    The dynamics of spontaneous fluctuations in neural activity are shaped by underlying patterns of anatomical connectivity. While numerous studies have demonstrated edge-wise correspondence between structural and functional connections, much less is known about how large-scale coherent functional network patterns emerge from the topology of structural networks. In the present study, we deploy a multivariate statistical technique, partial least squares, to investigate the association between spatially extended structural networks and functional networks. We find multiple statistically robust patterns, reflecting reliable combinations of structural and functional subnetworks that are optimally associated with one another. Importantly, these patterns generally do not show a one-to-one correspondence between structural and functional edges, but are instead distributed and heterogeneous, with many functional relationships arising from nonoverlapping sets of anatomical connections. We also find that structural connections between high-degree hubs are disproportionately represented, suggesting that these connections are particularly important in establishing coherent functional networks. Altogether, these results demonstrate that the network organization of the cerebral cortex supports the emergence of diverse functional network configurations that often diverge from the underlying anatomical substrate. PMID:27102654

  15. Structural properties of spatially embedded networks

    Kosmidis, K.; Havlin, S.; Bunde, A.

    2008-05-01

    We study the effects of spatial constraints on the structural properties of networks embedded in one- or two-dimensional space. When nodes are embedded in space, they have a well-defined Euclidean distance r between any pair. We assume that nodes at distance r have a link with probability p(r)~r-δ. We study the mean topological distance l and the clustering coefficient C of these networks and find that they both exhibit phase transitions for some critical value of the control parameter δ depending on the dimensionality d of the embedding space. We have identified three regimes. When δ2d the networks are "large" worlds l~N1/d with high clustering. Our results indicate that spatial constrains have a significant impact on the network properties, a fact that should be taken into account when modeling complex networks.

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

    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......, exhibiting satisfactory construct validity, including factorspecific links to the model of adult attachment (Bartholomew & Horowitz, 1991), and independent factor discrimination between subgroups. A robust validation supports the application of the ECR-RS to assessing relationship-specific adolescent...

  17. The Relationship between Financial Flexibility and Capital Structure Decisions

    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.

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

    Alejandra J. Monsiváis-Barrón

    2014-10-01

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

  19. Function-structure relationships of acetylated pea starches

    J. Huang

    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 size fractions. The amount of introduced acetyl groups was found to depend on the size of the granules for the reaction with rapidly reacting reagent acetic acid anhydride, whereas the amount of intr...

  20. Relationships between milk coagulation property traits analyzed with different methodologies.

    Pretto, D; Kaart, T; Vallas, M; Jõudu, I; Henno, M; Ancilotto, L; Cassandro, M; Pärna, E

    2011-09-01

    Milk coagulation properties (MCP) analysis is performed using a wide range of methodologies in different countries and laboratories, using different instruments, coagulant activity in the milk, and type of coagulant. This makes it difficult to compare results and data from different research. The aims of this study were to propose a method for the transformation of values of rennet coagulation time (RCT) and curd firmness (a(30)) and to predict the noncoagulation (NC) probability of milk samples analyzed using different methodologies. Individual milk samples were collected during the morning milking in October 2010 from each of 165 Holstein-Friesian dairy cows in 2 freestall barns in Italy, and sent to 3 laboratories for MCP analysis. For each laboratory, MCP analysis was performed using a different methodology: A, with a computerized renneting meter instrument using 0.051 international milk clotting units (IMCU)/mL of coagulant activity; B, with a Lattodinamografo (Foss-Italia, Padova, Italy) using 0.051 IMCU/mL of coagulant activity; and C, with an Optigraph (Ysebaert, Frépillon, France) using 0.120 IMCU/mL of coagulant activity. The relationships between MCP traits were analyzed with correlation and regression analyses for each pair of methodologies. For each MCP trait, 2 regression models were applied: model 1 was a single regression model, where the dependent and independent variables were the same MCP trait determined by 2 different methodologies; in model 2, both a(30) and RCT were included as independent variables. The NC probabilities for laboratories with the highest number of NC samples were predicted based on the RCT and a(30) values measured in the laboratories with lower number of NC samples using logistic regression and receiver operating characteristic analysis. The percentages of NC samples were 4.2, 11.5, and 0.6% for A, B, and C, respectively. The transformation of MCP traits was more precise with model 1 for RCT (R(2): 0.77-0.82) than for a(30

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

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

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

    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 HPO42− 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

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

    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.

  4. Concerning phase relationships which are not structure invariants or seminvariants

    Often some primitive random variables (e.g. the atomic coordinates) are non-uniformly distributed over the unit cell. Prior information about such distributions is often available but not always used in current direct-methods procedures. Examples are described according to which primitive random variables are restricted to some domains (attended domains) or, in an equivalent way, are prevented from frequenting some domains (forbidden domains). Emphasis has been put on the fact that non-uniform distributions generate phase relation-ships which are not structure invariants or seminvariants, but it is also anticipated that formulas for estimating phase invariants and seminvariants are deeply affected by such prior information. (orig.)

  5. Relationship structure-antioxidant activity of hindered phenolic compounds

    Weng, X. C.; Huang, Y.

    2014-01-01

    The relationship between the structure and the antioxidant activity of 21 hindered phenolic compounds was investigated by Rancimat and DPPH· tests. 3-tert-butyl-5-methylbenzene-1,2-diol is the strongest antioxidant in the Rancimat test but not in the DPPH· test because its two hydroxyl groups have very strong steric synergy. 2,6-Ditert-butyl-4-hydroxy-methylphenol exhibits a strong antioxidant activity as 2,6-ditertbutyl- 4-methoxyphenol does in lard. 2,6-Ditert-butyl-4- hydroxy-methylphenol ...

  6. Structural properties of spatially embedded networks

    Kosmidis, Kosmas; Havlin, Shlomo; Bunde, Armin

    2008-01-01

    We study the effects of spatial constraints on the structural properties of networks embedded in one or two dimensional space. When nodes are embedded in space, they have a well defined Euclidean distance $r$ between any pair. We assume that nodes at distance $r$ have a link with probability $p(r) \\sim r^{- \\delta}$. We study the mean topological distance $l$ and the clustering coefficient $C$ of these networks and find that they both exhibit phase transitions for some critical value of the c...

  7. STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

    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.

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

    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.

  9. The relationship between energy consumption structure, economic structure and energy intensity in China

    Feng, Taiwen; Sun, Linyan; Zhang, Ying [School of Management, Xi' an Jiaotong University, Xi' an (China); The Key Laboratory of the Ministry of Education for Process Control and Efficiency Projects, Xi' an (China); The State Key Lab for Manufacturing, Xi' an (China)

    2009-12-15

    This paper investigates the long-run equilibrium relationships, temporal dynamic relationships and causal relationships between energy consumption structure, economic structure and energy intensity in China. Time series variables over the periods from 1980 to 2006 are employed in empirical tests. Cointegration tests suggest that these three variables tend to move together in the long-run. In addition, Granger causality tests indicate that there is a unidirectional causality running from energy intensity to economic structure but not vice versa. Impulse response analysis provides reasonable evidences that one shock of the three variables will cause the periods of destabilized that followed. However, the impact of the energy consumption structure shock on energy intensity and the impact of the economic structure shock on energy consumption structure seem to be rather marginal. The findings have significant implications from the point of view of energy conservation and economic development. In order to decrease energy intensity, Chinese government must continue to reduce the proportion of coal in energy consumption, increase the utilization efficiency of coal and promote the upgrade of economic structure. Furthermore, a full analysis of factors that may relate to energy intensity (e.g. energy consumption structure, economic structure) should be conducted before making energy policies. (author)

  10. The relationship between energy consumption structure, economic structure and energy intensity in China

    Feng Taiwen, E-mail: typhoonfeng@gmail.co [School of Management, Xi' an Jiaotong University, Xi' an (China); Key Laboratory of the Ministry of Education for Process Control and Efficiency Projects, Xi' an (China); School of Management, Xi' an Jiaotong University, Xi' an (China); Sun Linyan [School of Management, Xi' an Jiaotong University, Xi' an (China); Key Laboratory of the Ministry of Education for Process Control and Efficiency Projects, Xi' an (China); School of Management, Xi' an Jiaotong University, Xi' an (China); Zhang Ying [School of Management, Xi' an Jiaotong University, Xi' an (China); Key Laboratory of the Ministry of Education for Process Control and Efficiency Projects, Xi' an (China); State Key Lab for Manufacturing, Xi' an (China)

    2009-12-15

    This paper investigates the long-run equilibrium relationships, temporal dynamic relationships and causal relationships between energy consumption structure, economic structure and energy intensity in China. Time series variables over the periods from 1980 to 2006 are employed in empirical tests. Cointegration tests suggest that these three variables tend to move together in the long-run. In addition, Granger causality tests indicate that there is a unidirectional causality running from energy intensity to economic structure but not vice versa. Impulse response analysis provides reasonable evidences that one shock of the three variables will cause the periods of destabilized that followed. However, the impact of the energy consumption structure shock on energy intensity and the impact of the economic structure shock on energy consumption structure seem to be rather marginal. The findings have significant implications from the point of view of energy conservation and economic development. In order to decrease energy intensity, Chinese government must continue to reduce the proportion of coal in energy consumption, increase the utilization efficiency of coal and promote the upgrade of economic structure. Furthermore, a full analysis of factors that may relate to energy intensity (e.g. energy consumption structure, economic structure) should be conducted before making energy policies.

  11. Extraordinary electronic properties in uncommon structure types

    Ali, Mazhar Nawaz

    In this thesis I present the results of explorations into several uncommon structure types. In Chapter 1 I go through the underlying idea of how we search for new compounds with exotic properties in solid state chemistry. The ideas of exploring uncommon structure types, building up from the simple to the complex, using chemical intuition and thinking by analogy are discussed. Also, the history and basic concepts of superconductivity, Dirac semimetals, and magnetoresistance are briefly reviewed. In chapter 2, the 1s-InTaS2 structural family is introduced along with the discovery of a new member of the family, Ag0:79VS2; the synthesis, structure, and physical properties of two different polymorphs of the material are detailed. Also in this chapter, we report the observation of superconductivity in another 1s structure, PbTaSe2. This material is especially interesting due to it being very heavy (resulting in very strong spin orbit coulping (SOC)), layered, and noncentrosymmetric. Electronic structure calculations reveal the presence of a bulk 3D Dirac cone (very similar to graphene) that is gapped by SOC originating from the hexagonal Pb layer. In Chapter 3 we show the re-investigation of the crystal structure of the 3D Dirac semimetal, Cd3As2. It is found to be centrosymmetric, rather than noncentrosymmetric, and as such all bands are spin degenerate and there is a 4-fold degenerate bulk Dirac point at the Fermi level, making Cd3As2 a 3D electronic analog to graphene. Also, for the first time, scanning tunneling microscopy experiments identify a 2x2 surface reconstruction in what we identify as the (112) cleavage plane of single crystals; needle crystals grow with a [110] long axis direction. Lastly, in chapter 4 we report the discovery of "titanic" (sadly dubbed ⪉rge, nonsaturating" by Nature editors and given the acronym XMR) magnetoresistance (MR) in the non-magnetic, noncentrosymmetric, layered transition metal dichalcogenide WTe2; over 13 million% at 0.53 K in

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

    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

  13. Atomic Scale Structure-Chemistry Relationships at Oxide Catalyst Surfaces and Interfaces

    McBriarty, Martin E.

    Oxide catalysts are integral to chemical production, fuel refining, and the removal of environmental pollutants. However, the atomic-scale phenomena which lead to the useful reactive properties of catalyst materials are not sufficiently understood. In this work, the tools of surface and interface science and electronic structure theory are applied to investigate the structure and chemical properties of catalytically active particles and ultrathin films supported on oxide single crystals. These studies focus on structure-property relationships in vanadium oxide, tungsten oxide, and mixed V-W oxides on the surfaces of alpha-Al2O3 and alpha-Fe2O 3 (0001)-oriented single crystal substrates, two materials with nearly identical crystal structures but drastically different chemical properties. In situ synchrotron X-ray standing wave (XSW) measurements are sensitive to changes in the atomic-scale geometry of single crystal model catalyst surfaces through chemical reaction cycles, while X-ray photoelectron spectroscopy (XPS) reveals corresponding chemical changes. Experimental results agree with theoretical calculations of surface structures, allowing for detailed electronic structure investigations and predictions of surface chemical phenomena. The surface configurations and oxidation states of V and W are found to depend on the coverage of each, and reversible structural shifts accompany chemical state changes through reduction-oxidation cycles. Substrate-dependent effects suggest how the choice of oxide support material may affect catalytic behavior. Additionally, the structure and chemistry of W deposited on alpha-Fe 2O3 nanopowders is studied using X-ray absorption fine structure (XAFS) measurements in an attempt to bridge single crystal surface studies with real catalysts. These investigations of catalytically active material surfaces can inform the rational design of new catalysts for more efficient and sustainable chemistry.

  14. Barley stripe mosaic virus: Structure and relationship to the tobamoviruses

    Barley stripe mosaic virus (BSMV) is the type member of the genus Hordeivirus, rigid, rod-shaped viruses in the family Virgaviridae. We have used fiber diffraction and cryo-electron microscopy to determine the helical symmetry of BSMV to be 23.2 subunits per turn of the viral helix, and to obtain a low-resolution model of the virus by helical reconstruction methods. Features in the model support a structural relationship between the coat proteins of the hordeiviruses and the tobamoviruses. - Highlights: • We report a low-resolution structure of barley stripe mosaic virus. • Barley stripe mosaic virus has 23.2 subunits per turn of the viral helix. • We compare barley stripe mosaic virus with tobacco mosaic virus

  15. 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

    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

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

    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

  17. 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

    Ling Gabriel Hoh Teck; Ho Chin Siong; Ali Hishamuddin Mohd; Tu Fan

    2016-01-01

    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 r...

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

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

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

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

    2015-04-17

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

  20. Structural Properties of Realistic Cultural Space Distributions

    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...

  1. Mullite Ceramics: Its Properties Structure and Synthesis

    Juliana Anggono

    2005-01-01

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

  2. Analysis and Projection of the Relationship between Industrial Structure and Land Use Structure in China

    Qin Jin

    2014-12-01

    Full Text Available Based on the computable general equilibrium (CGE modelling method, this research analyzes the relationship between industrial structure and land use structure in China. The results show that our model is feasible, and the simulation results are of a certain stability. Under the scenario analysis and projection of the relationship between the industrial structure and land use structure of the thirty-one provinces in China from 2010 to 2020, the proportions of secondary and tertiary industry in each province have been increasing; correspondingly, the proportion of agriculture has been decreasing. This means that the industrial structure of China is changing. As for land use, in general, the trend is similar to the industrial structure changes. The transformation of the structure of industrial development and land use has driven economic structure changes in China. The economic structure has an inclination to transform from agriculture to both secondary and tertiary industry. Along with industrial transformation, the cultivated land in China shows a trend of continuous decline. Empirical analysis results indicate that a decrease of cultivated land is acceptable under the scenario of economic growth in the next ten years. This shows a possibility that the economic efficiency of land use for cultivation and business services will decline, and more attention ought to be paid to increasing the economic efficiency of land use.

  3. Structure Property Studies for Additively Manufactured Parts

    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.

  4. Relationship between structure and catalytic performance of dealuminated Y zeolites

    Dealuminated Y zeolites which have been prepared by hydrothermal and chemical treatments show differences in catalytic performance when tested fresh; however, these differences disappear after the zeolites have been steamed. The catalytic behavior of fresh and steamed zeolites is directly related to zeolite structural and chemical characteristics. Such characteristics determine the strength and density of acid sites for catalytic cracking. Dealuminated zeolites were characterized using x-ray diffraction, porosimetry, solid-state NMR and elemental analysis. Hexadecane cracking was used as a probe reaction to determine catalytic properties. Cracking activity was found to be proportional to total aluminum content in the zeolite. Product selectivity was dependent on unit cell size, presence of extra framework alumina and spatial distribution of active sites. The results from this study elucidate the role that zeolite structure plays in determining catalytic performance

  5. Structure and Relationships of University Instructors’ Achievement Goals

    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.

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

    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.

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

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

  8. Structure-activity relationship of endomorphins and their analogs

    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.

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

    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.

  10. Structure and function relationships of the respiratory muscles.

    Sauleda, J; Gea, J; Orozco-Levi, M; Corominas, J; Minguella, J; Aguar, C; Broquetas, J; Agustí, A G

    1998-04-01

    Potential relationships between the structure of the diaphragm and external intercostals and several indices of respiratory muscle function, lung function and nutrition in 27 patients (61+/-10 yrs of age) subjected to thoracotomy as a result of a lung neoplasm have been investigated. Prior to surgery the nutritional status of the patients was assessed and lung function (spirometry, lung volumes, transfer factor of the lungs for carbon monoxide, arterial blood gases) and respiratory muscle function (maximal inspiratory pressure (MIP) and diaphragmatic function were measured). Biopsies of the diaphragm (and external intercostals) were obtained during surgery. On average, patients showed mild airflow limitation (forced expiratory volume in one second (FEV1), 70+/-14% of predicted value, FEV1/forced vital capacity (FVC), 70+/-9%) with some air trapping (residual volume (RV), 139+/-50% pred) and normal gas exchange (arterial oxygen tension (Pa,O2), 11.3+/-1.33 kPa (85+/-10 mmHg)) and arterial carbon dioxide tension (Pa,CO2) 5.4+/-0.5 kPa (40.6+/-4 mmHg). MIP was 77+/-25% pred; maximal transdiaphragmatic pressure was 90+/-27 cmH2O. Most morphometric measurements of the diaphragm and external intercostals were within the range of values reported previously in other skeletal muscles. The size of the fibres of these two respiratory muscles was positively related (p<0.05) to MIP (% pred). There were no significant relationships between the structure of both muscles and nutritional status or any index of lung function. In conclusion, in the population studied, the fibre size of the diaphragm and external intercostals appears to relate to their ability to generate force. PMID:9623696

  11. High-pressure structural properties of tetramethylsilane

    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).

  12. Structural Properties of Green Tea Catechins.

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

    2015-10-01

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

  13. Development of methacrylate/silorane hybrid monomer system: Relationship between photopolymerization behavior and dynamic mechanical properties.

    Song, Linyong; Ye, Qiang; Ge, Xueping; Singh, Viraj; Misra, Anil; Laurence, Jennifer S; Berrie, Cindy L; Spencer, Paulette

    2016-07-01

    Resin chemistries for dental composite are evolving as noted by the introduction of silorane-based composites in 2007. This shift in the landscape from methacrylate-based composites has fueled the quest for versatile methacrylate-silorane adhesives. The objective of this study was to evaluate the polymerization behavior and structure/property relationships of methacrylate-silorane hybrid systems. Amine compound ethyl-4-(dimethylamino) benzoate (EDMAB) or silane compound tris(trimethylsilyl) silane (TTMSS) was selected as coinitiators. The mechanical properties of the copolymer were improved significantly at low concentrations (15, 25, or 35 wt %) of silorane when EDMAB was used as coinitiator. The rubbery moduli of these experimental copolymers were increased by up to 260%, compared with that of the control (30.8 ± 1.9 MPa). Visible phase separation appeared in these formulations if the silorane concentrations in the formulations were 50-75 wt %. The use of TTMSS as coinitiator decreased the phase separation, but there was a concomitant decrease in mechanical properties. In the neat methacrylate formulations, the maximum rates of free-radical polymerization with EDMAB or TTMSS were 0.28 or 0.06 s(-1) , respectively. In the neat silorane resin, the maximum rates of cationic ring-opening polymerization with EDMAB or TTMSS were 0.056 or 0.087 s(-1) , respectively. The phase separation phenomenon may be attributed to differences in the rates of free-radical polymerization of methacrylates and cationic ring-opening polymerization of silorane. In the hybrid systems, free-radical polymerization initiated with EDMAB led to higher crosslink density and better mechanical properties under dry/wet conditions. These beneficial effects were, however, associated with an increase in heterogeneity in the network structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 841-852, 2016. PMID:25953619

  14. Relationship between Magnetic and Mechanical Properties of Cermet Tools

    The commercial cermet cutting tools consist of multi-carbide and a binder metal of iron group, such as cobalt and nickel which are ferromagnetic. In this paper, a new approach to evaluate the mechanical properties of TiCN based cermet by magnetic properties were studied in relation to binder content and sintering conditions. The experimental cermet was prepared using commercial composition with the other binder contents by PM process. It was found that the magnetic properties of the sintered cermets remarkably depended on the microstructure and the total carbon content. The magnetic saturation was proportional to increment of coercive force. At high carbon content in sintered cermet, the magnetic saturation was increased by decreasing the concentration of solutes such as W, Mo, Ti in Co-Ni binder. As the coercive force increases, the hardness usually increases. The strength and toughness of the cermet also increased with increasing the magnetic saturation. The measurement of magnetic properties made it possible to evaluate the mechanical properties in the cermet cutting tools

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

    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. The NBS: Processing/Microstructure/Property Relationships in 2024 Aluminum Alloy Plates

    Ives, L. K.; Swartzendruber, W. J.; Boettinger, W. J.; Rosen, M.; Ridder, S. D.

    1983-01-01

    As received plates of 2024 aluminum alloy were examined. Topics covered include: solidification segregation studies; microsegregation and macrosegregation in laboratory and commercially cast ingots; C-curves and nondestructive evaluation; time-temperature precipitation diagrams and the relationships between mechanical properties and NDE measurements; transmission electron microscopy studies; the relationship between microstructure and properties; ultrasonic characterization; eddy-current conductivity characterization; the study of aging process by means of dynamic eddy current measurements; and Heat flow-property predictions, property degradations due to improve quench from the solution heat treatment temperature.

  17. Critically Evaluated Database of Environmental Properties: The Importance of Thermodynamic Relationships, Chemical Family Trends, and Prediction Methods

    Brockbank, Sarah A.; Russon, Jenna L.; Giles, Neil F.; Rowley, Richard L.; Wilding, W. Vincent

    2013-11-01

    A database containing Henry's law constants, infinite dilution activity coefficients, and solubility data of industrially important chemicals has been compiled for aqueous systems. These properties are important in predicting the fate and transport of chemicals in the environment. The structure of this database is compatible with the existing 801 database and DIADEM interface, and data are included for a subset of compounds found in the 801 database. Thermodynamic relationships, chemical family trends, and predicted values were carefully considered when designating recommended values.

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

    Low, I.M. [Materials Research Group, Department of Applied Physics, Curtin University of Technology, Perth, WA 6845 (Australia)], E-mail: j.low@curtin.edu.au; Duraman, N.; Mahmood, U. [Materials Research Group, Department of Applied Physics, Curtin University of Technology, Perth, WA 6845 (Australia)

    2008-03-10

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

  19. Chitosan/halloysite nanotubes bionanocomposites: structure, mechanical properties and biocompatibility.

    Liu, Mingxian; Zhang, Yun; Wu, Chongchao; Xiong, Sheng; Zhou, Changren

    2012-11-01

    Incorporation of nanosized reinforcements into chitosan usually results in improved properties and changed microstructures. Naturally occurred halloysite nanotubes (HNTs) are incorporated into chitosan for forming bionanocomposite films via solution casting. The electrostatic attraction and hydrogen bonding interactions between HNTs and chitosan are confirmed. HNTs are uniformly dispersed in chitosan matrix. The tensile strength and Young's modulus of chitosan are enhanced by HNTs. The storage modulus and glass transition temperature of chitosan/HNTs films also increase significantly. Blending with HNTs induces changes in surface nanotopography and increase of roughness of chitosan films. In vitro fibroblasts response demonstrates that both chitosan and chitosan/HNTs nanocomposite films are cytocompatibility even when the loading of HNTs is 10%. In summary, these results provide insights into understanding of the structural relationships of chitosan/HNTs bionanocomposite films in potential applications, such as scaffold materials in tissue engineering. PMID:22743347

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

    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.

  1. Thermal-structural relationship of individual titania nanotubes

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

    2015-11-01

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

  2. Structure and mechanical properties of irradiated magnesium aluminate spinel

    Devanathan, R.; Yu, N.; Sickafus, K. E.; Nastasi, M.

    1996-09-01

    The relationship between structure and mechanical properties of MgAl 2O 4 spinel single crystals following 400 keV Xe 2+ irradiation at 100 K to doses up to 1 × 10 20 ions/m 2 was examined. The structural changes in the irradiated layer were studied using electron diffraction from cross-sectional samples. The nano-indentation technique was used to determine the mechanical properties. At low doses, the material transformed into a metastable crystalline phase characterized by the rearrangement of cations. At the onset of this transformation, the Young's modulus and hardness rose to values about 10 and 15% higher, respectively, than those of the unirradiated crystal. Upon further irradiation, the metastable crystal became amorphous. The Young's modulus and hardness of the amorphous state were about 30 and 60% less, respectively, than the corresponding values of unirradiated spinel. These results, in conjunction with the findings of a recent computer simulation study, provide important insights into the exceptional radiation resistance of magnesium aluminate spinel.

  3. Structure and mechanical properties of irradiated magnesium aluminate spinel

    Devanathan, R. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Yu, N. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Sickafus, K.E. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Nastasi, M. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    1996-09-01

    The relationship between structure and mechanical properties of MgAl{sub 2}O{sub 4} spinel single crystals following 400 keV Xe{sup 2+} irradiation at 100 K to doses up to 1.10{sup 20} ions/m{sup 2} was examined. The structural changes in the irradiated layer were studied using electron diffraction from cross-sectional samples. The nano-indentation technique was used to determine the mechanical properties. At low doses, the material transformed into a metastable crystalline phase characterized by the rearrangement of cations. At the onset of this transformation, the Young`s modulus and hardness rose to values about 10 and 15% higher, respectively, than those of the unirradiated crystal. Upon further irradiation, the metastable crystal became amorphous. The Young`s modulus and hardness of the amorphous state were about 30 and 60% less, respectively, than the corresponding values of unirradiated spinel. These results, in conjunction with the findings of a recent computer simulation study, provide important insights into the exceptional radiation resistance of magnesium aluminate spinel. (orig.).

  4. Structure and mechanical properties of irradiated magnesium aluminate spinel

    The relationship between structure and mechanical properties of MgAl2O4 spinel single crystals following 400 keV Xe2+ irradiation at 100 K to doses up to 1.1020 ions/m2 was examined. The structural changes in the irradiated layer were studied using electron diffraction from cross-sectional samples. The nano-indentation technique was used to determine the mechanical properties. At low doses, the material transformed into a metastable crystalline phase characterized by the rearrangement of cations. At the onset of this transformation, the Young's modulus and hardness rose to values about 10 and 15% higher, respectively, than those of the unirradiated crystal. Upon further irradiation, the metastable crystal became amorphous. The Young's modulus and hardness of the amorphous state were about 30 and 60% less, respectively, than the corresponding values of unirradiated spinel. These results, in conjunction with the findings of a recent computer simulation study, provide important insights into the exceptional radiation resistance of magnesium aluminate spinel. (orig.)

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

    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.

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

    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

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

    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: .

  8. Structure-function relationships in fungal large-subunit catalases.

    Díaz, Adelaida; Valdés, Víctor-Julián; Rudiño-Piñera, Enrique; Horjales, Eduardo; Hansberg, Wilhelm

    2009-02-13

    Neurospora crassa has two large-subunit catalases, CAT-1 and CAT-3. CAT-1 is associated with non-growing cells and accumulates particularly in asexual spores; CAT-3 is associated with growing cells and is induced under different stress conditions. It is our interest to elucidate the structure-function relationships in large-subunit catalases. Here we have determined the CAT-3 crystal structure and compared it with the previously determined CAT-1 structure. Similar to CAT-1, CAT-3 hydrogen peroxide (H(2)O(2)) saturation kinetics exhibited two components, consistent with the existence of two active sites: one saturated in the millimolar range and the other in the molar range. In the CAT-1 structure, we found three interesting features related to its unusual kinetics: (a) a constriction in the channel that conveys H(2)O(2) to the active site; (b) a covalent bond between the tyrosine, which forms the fifth coordination bound to the iron of the heme, and a vicinal cysteine; (c) oxidation of the pyrrole ring III to form a cis-hydroxyl group in C5 and a cis-gamma-spirolactone in C6. The site of heme oxidation marks the starts of the central channel that communicates to the central cavity and the shortest way products can exit the active site. CAT-3 has a similar constriction in its major channel, which could function as a gating system regulated by the H(2)O(2) concentration before the gate. CAT-3 functional tyrosine is not covalently bonded, but has instead the electron relay mechanism described for the human catalase to divert electrons from it. Pyrrole ring III in CAT-3 is not oxidized as it is in other large-subunit catalases whose structure has been determined. Different in CAT-3 from these enzymes is an occupied central cavity. Results presented here indicate that CAT-3 and CAT-1 enzymes represent a functional group of catalases with distinctive structural characteristics that determine similar kinetics. PMID:19109972

  9. Quantitative structure-(chromatographic) retention relationship models for dissociating compounds.

    Kubik, Łukasz; Wiczling, Paweł

    2016-08-01

    The aim of this work was to develop mathematical models relating the hydrophobicity and dissociation constant of an analyte with its structure, which would be useful in predicting analyte retention times in reversed-phase liquid chromatography. For that purpose a large and diverse group of 115 drugs was used to build three QSRR models combining retention-related parameters (logkw-chromatographic measure of hydrophobicity, S-slope factor from Snyder-Soczewinski equation, and pKa) with structural descriptors calculated by means of molecular modeling for both dissociated and nondissociated forms of analytes. Lasso, Stepwise and PLS regressions were used to build statistical models. Moreover a simple QSRR equations based on lipophilicity and dissociation constant parameters calculated in the ACD/Labs software were proposed and compared with quantum chemistry-based QSRR equations. The obtained relationships were further used to predict chromatographic retention times. The predictive performances of the obtained models were assessed using 10-fold cross-validation and external validation. The QSRR equations developed were simple and were characterized by satisfactory predictive performance. Application of quantum chemistry-based and ACD-based descriptors leads to similar accuracy of retention times' prediction. PMID:26960942

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

    D. Pugazhenthi

    2009-01-01

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

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

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

    2006-01-01

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

  12. Processing-property relationships of polypropylene/ciprofloxacin fibers

    Botta, L.; Scaffaro, R.

    2015-12-01

    In this work we prepared polypropylene (PP) fibers incorporating an antibiotic, i.e. ciprofloxacin (CFX), by melt spinning. In particular, PP has been compounded with CFX at different concentrations by using a counter-rotating twin screw compounder. The PP/CFX fibers have been spun by using a capillary rheometer operating under a constant extrusion speed. The effect of "online" hot drawing during the melt spinning or of an "offline" cold drawing on the properties of PP/CFX fibers were evaluated. In particular, the influence of the drawing conditions on the mechanical properties and the release kinetics were studied. Moreover, the rheological behavior in non-isothermal elongation flow has been assessed.

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

    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

  14. Property-process relationships in nuclear fuel fabrication

    Nuclear fuels are fabricated using many different techniques as they come in a large variety of shapes and compositions. The design and composition of nuclear fuels are predominantly dictated by the engineering requirements necessary for their function in reactors of various designs. Other engineering properties requirements originate from safety and security concerns, and the easy of handling, storing, transporting and disposing of the radioactive materials. In this chapter, the more common of these fuels will be briefly reviewed and the methods used to fabricate them will be presented. The fuels considered in this paper are oxide fuels used in LWRs and FRs, metal fuels in FRs and particulate fuels used in HTGRs. Fabrication of alternative fuel forms and use of standard fuels in alternative reactors will be discussed briefly. The primary motivation to advance fuel fabrication is to improve performance, reduce cost, reduce waste or enhance safety and security of the fuels. To achieve optimal performance, developing models to advance fuel fabrication has to be done in concert with developing fuel performance models. The specific properties and microstructures necessary for improved fuel performance must be identified using fuel performance models, while fuel fabrication models that can determine processing variables to give the desired microstructure and materials properties must be developed. (author)

  15. Institutional Structure and International Competitiveness Relationship in Developed Countries

    Aynur Yıldırım

    2016-06-01

    Full Text Available This study analyzes the effects of institutional structure on the international competitiveness of developed countries econometrically by employing a “Panel Data Analysis” with a sample of 21 developed countries and 23 institutional variables for the period 2000-2011. The results of the analysis indicate that while judicial independence, protection of intellectual property rights, integrity of the juridical system, marginal tax, political freedoms, black market exchange rate, restrictions on foreign investment, private sector’s share in the banking system, hiring-minimum wage, and hiring-dismissal have a positive effect; the nature of legal arrangements, government spending, transfers and subsidies, civil liberties, tariffs, regulations regarding trade barriers, collective bargaining, and military tutelage have a negative effect on the international competitiveness of developed countries.

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

    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…

  17. Percolation and structural properties of particle deposits

    We investigate the percolation properties of configurations of spherical particles deposited by a generalized ballistic deposition model. In this model, a tuning parameter a is introduced for controlling the relative efficiency of two mechanisms: direct deposition and deposition by following the path of steepest descent on previously deposited particles. Any particle that is trapped in an elevated position after rolling is rejected. Exact critical exponents are obtained for the (1+1)-dimensional version of the model. We performed computer simulations of the (2+1)-dimensional version and by studying the percolative behavior both for fixed values of a, as a function of the surface coverage θ, and along the saturation curve θ(a,∞), we construct the percolation phase diagram of the model. Below a threshold value, ac congruent 3.05, there is no percolation transition, but we give some evidence for a ''virtual percolation line.'' The critical exponents β,γ,ν are determined by finite-size scaling and Monte Carlo renormalization group techniques, and are shown to be consistent with those of ordinary two-dimensional lattice percolation. Finally, changes of structure with a are illustrated through the pair distribution function and the pair connectedness function

  18. Nanotwinned silver nanowires: Structure and mechanical properties

    Ag nanowires have been manufactured with the ultrathin layer electrochemical deposition method. Transmission electron microscopy revealed a multiple twinned nanostructure that has not been reported in comparable structures using a non-template self-assembling preparation method. The {1 1 1} twin planes are oriented parallel to the 〈1 1 2〉 wire axis. The influence of the twin boundaries on the elastic and plastic properties of these wires has been investigated. Atomistic calculations revealed no influence of the twin boundaries on the Young’s modulus of the wire for this geometry and along the 〈1 1 2〉 direction. However, the twin boundaries exhibited a strong orientation-dependent influence on the plastic deformation when indented orthogonal (〈1 1 1〉 direction) or parallel (〈1 1 0〉 direction) to the twin boundaries, reflecting the interaction between the glide systems active in fcc metals and the stress direction. Heating experiments showed a high heat resistance for the twin boundaries till sublimation in an in situ TEM heating experiment. Sublimation followed the twin boundaries, indicating the lower binding energy of hcp stacking in comparison to fcc stacking.

  19. Structure and properties of hybrid coatings

    Full text: This review report presents both the results obtained by the authors and those of other authors concerning investigations of structure and properties of hybrid coatings. Examples of such coatings as Al2O3/Cr/TiN/steel, TiC; TiN/Ti-V-Al; NiCr/steel; CrNiBSi/steel and others before and after electron beam irradiation had been considered. In these coatings the thickest layer was deposited using the high-velocity pulsed plasma jet, all others being deposited in vacuum by the vacuum-arc source or implanter. Advantages of the high-velocity pulsed plasma jet in comparison with other technologies had been demonstrated. A wide spectrum of analyzing methods had been applied for analyses: TEM, SEM with EDS, RBS, NRA, SIMS, XRD, tests for corrosion, wear, adhesion and hardness. The works had been funded by the Project 2M/03 54-2003 of the Ministry of Science and Education of Ukraine and STCU Project N3078

  20. Crystalline mesophases: Structure, mobility, and pharmaceutical properties.

    Shalaev, Evgenyi; Wu, Ke; Shamblin, Sheri; Krzyzaniak, Joseph F; Descamps, Marc

    2016-05-01

    Crystalline mesophases, which are commonly classified according to their translational, orientational, and conformational order as liquid crystals, plastic crystals, and conformationally disordered crystals, represent a common state of condensed matter. As an intermediate state between crystalline and amorphous materials, crystalline mesophases resemble amorphous materials in relation to their molecular mobility, with the glass transition being their common property, and at the same time possessing a certain degree of translational periodicity (with the exception of nematic phase), with corresponding narrow peaks in X-ray diffraction patterns. For example, plastic crystals, which can be formed both by near-spherical molecules and molecules of lower symmetry, such as planar or chain molecules, can have both extremely sharp X-ray diffraction lines and exhibit glass transition. Fundamentals of structural arrangements in mesophases are compared with several types of disorder in crystalline materials, as well as with short-range ordering in amorphous solids. Main features of the molecular mobility in crystalline mesophases are found to be generally similar to amorphous materials, although some important differences do exist, depending on a particular type of mobility modes involved in relaxation processes. In several case studies reviewed, chemical stability appears to follow the extent of disorder, with the stability of crystalline mesophase found to be intermediate between amorphous (least stable) and crystalline (most stable) materials. Finally, detection of crystalline mesophases during manufacturing of two different types of dosage forms is discussed. PMID:27067607

  1. Probing structure-antifouling activity relationships of polyacrylamides and polyacrylates.

    Zhao, Chao; Zhao, Jun; Li, Xiaosi; Wu, Jiang; Chen, Shenfu; Chen, Qiang; Wang, Qiuming; Gong, Xiong; Li, Lingyan; Zheng, Jie

    2013-07-01

    We have synthesized two different polyacrylamide polymers with amide groups (polySBAA and polyHEAA) and two corresponding polyacrylate polymers without amide groups (polySBMA and polyHEA), with particular attention to the evaluation of the effect of amide group on the hydration and antifouling ability of these systems using both computational and experimental approaches. The influence of polymer architectures of brushes, hydrogels, and nanogels, prepared by different polymerization methods, on antifouling performance is also studied. SPR and ELISA data reveal that all polymers exhibit excellent antifouling ability to repel proteins from undiluted human blood serum/plasma, and such antifouling ability can be further enhanced by presenting amide groups in polySBAA and polyHEAA as compared to polySBMA and polyHEA. The antifouling performance is positively correlated with the hydration properties. Simulations confirm that four polymers indeed have different hydration characteristics, while all presenting a strong hydration overall. Integration of amide group with pendant hydroxyl or sulfobetaine group in polymer backbones is found to increase their surface hydration of polymer chains and thus to improve their antifouling ability. Importantly, we present a proof-of-concept experiment to synthesize polySBAA nanogels, which show a switchable property between antifouling and pH-responsive functions driven by acid-base conditions, while still maintaining high stability in undiluted fetal bovine serum and minimal toxicity to cultured cells. This work provides important structural insights into how very subtle structural changes in polymers can yield great improvement in biological activity, specifically the inclusion of amide group in polymer backbone/sidechain enables to obtain antifouling materials with better performance for biomedical applications. PMID:23562049

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

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

    2014-01-01

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

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

    Bond, S A; Loizou, P.; McAllister, Patrick (Hrsg.)

    2005-01-01

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

  4. Comparing In Situ and Bulk Constitutive Properties of a Structural Adhesive

    Grohs, Joshua Walter

    2007-01-01

    In the continuing quest for more efficient designs, structural adhesives are being used in place of, or with, traditional fastening methods; however designing with adhesives is refined as traditional methods. To obtain the adhesive design properties, tests are often performed on bulk tensile and bonded shear specimens. Questions remain about the relationship between properties obtained from in situ adhesive joints and bulk adhesive specimens. As a result, an experimental plan was developed...

  5. Ownership structure and corporate performance: empirical evidence of China's listed property companies

    Ke, Q.; Isaac, D

    2007-01-01

    This paper investigates the relationship of ownership structure and corporate performance of China’s listed property companies. Data from all the listed property companies on China’s stock market from 2000 to 2002 to study ownership concentration, type of controlling shares and their relation to corporate performance. The methodology applied is the conventional ordinary least square (OLS) model which is widely used in empirical studies on corporate governance. We find that ownership concentra...

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

    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.

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

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

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

    S. del Rio

    2012-03-01

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

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

    C.H. Azhari; Wong, S F

    2001-01-01

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

  10. Molecular Structural and Properties of 3-chloro-4 (dichloromethyl)-5-hydroxy-2 [5H] -furanone (MX)

    李欣; 龙运前; 齐晶瑶; 王郁萍

    2004-01-01

    3 - chloro - 4 (dichloromethyl) - 5 - hydroxy - 2 [5H] - furanone (MX) formed during chlorination of water containing natural organic substances, is a very potent bacterial mutgen. Molecular mechanics calculations to evaluate the conformation of structure, and to determine structure relationship properties are put forward. The investigations allow the correlation of molecular structures of MX with its properties, such as mass,partial charges, steric energy, frontier molecular orbital. The VRML molecular models have been investigated using Virtual Reality software. The spectral simulation of MX is illustrated. The principal aim is to develop an efficient method which control of MX.

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

    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

  12. Structure-activity relationship of immunostimulatory effects of phthalates

    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.

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

    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. PMID:26884139

  14. Structure activity relationships to assess new chemicals under TSCA

    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.

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

    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.

  16. Structure-dynamics relationships in bursting neuronal networks revealed using a prediction framework.

    Tuomo Mäki-Marttunen

    Full Text Available The question of how the structure of a neuronal network affects its functionality has gained a lot of attention in neuroscience. However, the vast majority of the studies on structure-dynamics relationships consider few types of network structures and assess limited numbers of structural measures. In this in silico study, we employ a wide diversity of network topologies and search among many possibilities the aspects of structure that have the greatest effect on the network excitability. The network activity is simulated using two point-neuron models, where the neurons are activated by noisy fluctuation of the membrane potential and their connections are described by chemical synapse models, and statistics on the number and quality of the emergent network bursts are collected for each network type. We apply a prediction framework to the obtained data in order to find out the most relevant aspects of network structure. In this framework, predictors that use different sets of graph-theoretic measures are trained to estimate the activity properties, such as burst count or burst length, of the networks. The performances of these predictors are compared with each other. We show that the best performance in prediction of activity properties for networks with sharp in-degree distribution is obtained when the prediction is based on clustering coefficient. By contrast, for networks with broad in-degree distribution, the maximum eigenvalue of the connectivity graph gives the most accurate prediction. The results shown for small ([Formula: see text] networks hold with few exceptions when different neuron models, different choices of neuron population and different average degrees are applied. We confirm our conclusions using larger ([Formula: see text] networks as well. Our findings reveal the relevance of different aspects of network structure from the viewpoint of network excitability, and our integrative method could serve as a general framework for

  17. Structure-dynamics relationships in bursting neuronal networks revealed using a prediction framework.

    Mäki-Marttunen, Tuomo; Aćimović, Jugoslava; Ruohonen, Keijo; Linne, Marja-Leena

    2013-01-01

    The question of how the structure of a neuronal network affects its functionality has gained a lot of attention in neuroscience. However, the vast majority of the studies on structure-dynamics relationships consider few types of network structures and assess limited numbers of structural measures. In this in silico study, we employ a wide diversity of network topologies and search among many possibilities the aspects of structure that have the greatest effect on the network excitability. The network activity is simulated using two point-neuron models, where the neurons are activated by noisy fluctuation of the membrane potential and their connections are described by chemical synapse models, and statistics on the number and quality of the emergent network bursts are collected for each network type. We apply a prediction framework to the obtained data in order to find out the most relevant aspects of network structure. In this framework, predictors that use different sets of graph-theoretic measures are trained to estimate the activity properties, such as burst count or burst length, of the networks. The performances of these predictors are compared with each other. We show that the best performance in prediction of activity properties for networks with sharp in-degree distribution is obtained when the prediction is based on clustering coefficient. By contrast, for networks with broad in-degree distribution, the maximum eigenvalue of the connectivity graph gives the most accurate prediction. The results shown for small ([Formula: see text]) networks hold with few exceptions when different neuron models, different choices of neuron population and different average degrees are applied. We confirm our conclusions using larger ([Formula: see text]) networks as well. Our findings reveal the relevance of different aspects of network structure from the viewpoint of network excitability, and our integrative method could serve as a general framework for structure

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

    Alejandra J. Monsiváis-Barrón; Jaime Bonilla-Rios; Antonio Sánchez-Fernández

    2014-01-01

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

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

    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.

  20. Relationship Between the Processing Parameters and the Properties of Semi-solid Processed Al Alloys

    SangYullee; BomSokKin; SangYonglee; HanJunglee

    2001-01-01

    Relationship between the processing parameters and the properties of semi-solid processed Al alloys were studied and microstructure and mechanical properties of semi-solid processed Al parts for automobile application as a function of processing parameters were compared with those of die-cast parts and forged parts. In addition, the locations for the gate during the semi-solid processing were varied to elucidate the distribution of micro-porosities and resulting mechanical properties and the T6 heat tre...

  1. Common Structural Core of Three-Dozen Residues Reveals Intersuperfamily Relationships.

    Mönttinen, Heli A M; Ravantti, Janne J; Poranen, Minna M

    2016-07-01

    Identification of relationships among protein families or superfamilies is a challenge. However, functionally essential protein regions typically retain structural integrity, even when the corresponding protein sequences evolve. Consequently, comparison of protein structures enables deeper phylogenetic analyses than achievable through the use of sequence information only. Here, we focus on a group of distantly related viral and cellular enzymes involved in nucleic acid or nucleotide processing and synthesis. All these enzymes share an apparently similar protein fold at their active site, which resembles the palm subdomain of the right-hand-shaped polymerases. Using a structure-based hierarchical clustering method, we identified a common structural core of 36 equivalent residues for this functionally diverse group of enzymes, representing five protein superfamilies. Based on the properties of these 36 residues, we deduced a structural distance-based tree in which the proteins were accurately clustered according to the established family classification. Within this tree, the enzymes catalyzing genomic nucleic acid replication or transcription were separated from those performing supplementary nucleic acid or nucleotide processing functions. In addition, we found that the family Y DNA polymerases are structurally more closely related to the nucleotide cyclase superfamily members than to the other members of the DNA/RNA polymerase superfamily, and these enzymes share 88 equivalent residues comprising a Β: 1- Α: 1- Α: 2- Β: 2- Β: 3- Α: 3- Β: 4- Α: 4- Β: 5 fold. The results highlight the power of structure-based hierarchical clustering in identifying remote evolutionary relationships. Furthermore, our study implies that a protein substructure of only three-dozen residues can contain a substantial amount of information on the evolutionary history of proteins. PMID:26931141

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

    Kamdar, Akshay Rajprakash

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

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

    Serkis, Magdalena; Poreba, Rafal; Špírková, Milena

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

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

    Lejček, Pavel; Hoffmann, S.; Paidar, Václav

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

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

    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.

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

    Desrues, Oliver; Enemark, Heidi L.; Mueller-Harvey, I.;

    2013-01-01

    Some plant secondary metabolites as tannins have direct anthelminthic properties and may play a role in the control of nematodes in livestock. However, their great diversity in structural characteristics and different levels of content in plants are responsible for a highly variable response in...... anthelmintic activity, as measured in vitro. The aim of the present study was to assess the relationship between tannin structure and anthelmintic activity using an in vitro assay. We used a series of purified tannins (from 65% to 100% of purity) characterized for their degree of polymerization (m......DP), prodelphinidin/procyanidin (PC/PD) ratio and cis/trans ratio by thiolytic degradation. Tannins diluted in two concentrations in water, epigallocatechin gallate (EGCG), positive (ivermectin) and negative (water) controls were examined by the Larval Feeding Inhibition Assay (LFIA) with first stage larvae (L1) of...

  7. Quantitative structure retention relationship studies for predicting relative retention times of chlorinated phenols on gas chromatography

    2002-01-01

    A new method of quantitative structure-retention relationship(QSRR) studies was reported for predicting gas chromatography(GC) relative retention times(RRTs) of chlorinated phenols (CPs) using a DB-5 column.Chemical descriptors were calculated from the molecular structure of CPs and related to their gas chromatographic RRTs by using multiple linear regression analysis.The proposed model had a multiple square correlation coefficient R2 = 0.970,standard error SE = 0.0472,and significant level P = 0.0000.The QSRR model also reveals that the gas chromatographic relative retention times of CPs are associated with physicochemical property interactions with the stationary phase,and influenced by the number of chlorine and oxygen in the CP melecules.

  8. Species-function relationships shape ecological properties of the human gut microbiome.

    Vieira-Silva, Sara; Falony, Gwen; Darzi, Youssef; Lima-Mendez, Gipsi; Garcia Yunta, Roberto; Okuda, Shujiro; Vandeputte, Doris; Valles-Colomer, Mireia; Hildebrand, Falk; Chaffron, Samuel; Raes, Jeroen

    2016-01-01

    Despite recent progress, the organization and ecological properties of the intestinal microbial ecosystem remain under-investigated. Here, using a manually curated metabolic module framework for (meta-)genomic data analysis, we studied species-function relationships in gut microbial genomes and microbiomes. Half of gut-associated species were found to be generalists regarding overall substrate preference, but we observed significant genus-level metabolic diversification linked to bacterial life strategies. Within each genus, metabolic consistency varied significantly, being low in Firmicutes genera and higher in Bacteroides. Differentiation of fermentable substrate degradation potential contributed to metagenomic functional repertoire variation between individuals, with different enterotypes showing distinct saccharolytic/proteolytic/lipolytic profiles. Finally, we found that module-derived functional redundancy was reduced in the low-richness Bacteroides enterotype, potentially indicating a decreased resilience to perturbation, in line with its frequent association to dysbiosis. These results provide insights into the complex structure of gut microbiome-encoded metabolic properties and emphasize the importance of functional and ecological assessment of gut microbiome variation in clinical studies. PMID:27573110

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

    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.

  10. Electronic structure and the properties of solids the physics of the chemical bond

    Harrison, Walter A

    1980-01-01

    "Should be widely read by practicing physicists, chemists and materials scientists." - Philosophical Magazine In this comprehensive and innovative text, Professor Harrison (Stanford University) offers a basic understanding of the electronic structure of covalent and ionic solids, simple metals, transition metals, and their compounds. The book illuminates the relationships of the electronic structures of these materials and shows how to calculate dielectric, conducting, and bonding properties for each.

  11. Structural Analysis of Laplacian Spectral Properties of Large-Scale Networks

    Preciado, Victor M.; Jadbabaie, Ali; Verghese, George C.

    2011-01-01

    Using methods from algebraic graph theory and convex optimization, we study the relationship between local structural features of a network and spectral properties of its Laplacian matrix. In particular, we derive expressions for the so-called spectral moments of the Laplacian matrix of a network in terms of a collection of local structural measurements. Furthermore, we propose a series of semidefinite programs to compute bounds on the spectral radius and the spectral gap of the Laplacian mat...

  12. Effect of Backbone Structure on Membrane Properties for Poly(arylene ether) Random and Multiblock Copolymers

    Rowlett, Jarrett Robert

    2014-01-01

    Poly(arylene ether)s are a well-established class of thermoplastics that are known for their mechanical toughness, thermal stability, and fabrication into membranes. These materials can undergo a myriad of modifications including backbone structure variability, sulfonation, and crosslinking. In this dissertation, structure-property relationships are considered for poly(arylene ether)s with regard to membrane applications for proton exchange and gas separation membranes. All of the proton...

  13. Minimum-Free-Energy Distribution of RNA Secondary Structures: Entropic and Thermodynamic Properties of Rare Events

    Wolfsheimer, S; Hartmann, A. K.

    2008-01-01

    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 like $10^{-70}$ and to study the relationship between the sequence entropy and structural properti...

  14. Relationships between aging of PAHs and soil properties

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

  15. Environment-tensile property relationship in AISI 1018 steel

    Environment-material interaction depends on several concurrent and mutually competitive variables ranging from nature of the environment to composition of the steel and including: the test temperature; the time of exposure of the material to the environment; the deformation rate; and intrinsic microstructural effects; The present work is a characterization of strain rate and environment influences on the tensile properties of a steel, AISI 1018, having a fully spheroidized microstructure. Tensile tests were performed at ambient temperature (300 K) in environments which are mildly aggressive (moist laboratory air-relative humidity 50%) and inert (dry gaseous nitrogen). The specimens were deformed to failure at strain rates of 10-4sec-1 and 10-5sec-1. No appreciable increase in yield and tensile strengths was observed at the strain rate of 10-4sec-1. However, the increase in both was of the order of 10 to 12% at the strain rate of 10-5sec-1. Ductility showed no variation with strain rate, but increased in the inert environment at both strain rates. Both environment and strain rate were found to have little to no influence on reduction in area of the test specimens. The true fracture stress followed a similar trend to the yield strength and ultimate tensile strength. (author)

  16. Graph theory in structure-property correlations

    Vinogradova, M. G.; Fedina, Yu. A.; Papulov, Yu. G.

    2016-02-01

    The possibilities of the theoretical graph approach to the construction and interpretation of additive schemes for calculation and prediction are discussed. Working formulas are derived for calculating the thermodynamic properties of alkanes and their substitutes. The obtained algorithms are used to calculate thermodynamic properties of chloroalkanes that correspond to experimental values.

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

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

    2010-09-01

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

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

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

    2013-05-01

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

  19. Microstructure-property relationship in magnetoelectric bulk composites

    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.

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

    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.

  1. 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

    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

  2. A simple auxetic tubular structure with tuneable mechanical properties

    Ren, Xin; Shen, Jianhu; Ghaedizadeh, Arash; Tian, Hongqi; Xie, Yi Min

    2016-06-01

    Auxetic materials and structures are increasingly used in various fields because of their unusual properties. Auxetic tubular structures have been fabricated and studied due to their potential to be adopted as oesophageal stents where only tensile auxetic performance is required. However, studies on compressive mechanical properties of auxetic tubular structures are limited in the current literature. In this paper, we developed a simple tubular structure which exhibits auxetic behaviour in both compression and tension. This was achieved by extending a design concept recently proposed by the authors for generating 3D metallic auxetic metamaterials. Both compressive and tensile mechanical properties of the auxetic tubular structure were investigated. It was found that the methodology for generating 3D auxetic metamaterials could be effectively used to create auxetic tubular structures as well. By properly adjusting certain parameters, the mechanical properties of the designed auxetic tubular structure could be easily tuned.

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

    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. Relationship between liquid structure and property Ⅱ——Kinematic viscosity of Mg-9Al melt and its relationship with the microstructure%液态结构与性质关系Ⅱ——Mg-9Al熔体的运动黏度及与熔体微观结构的关系

    弭光宝; 李培杰; ОхапкиАВ; Kонстантиннова Н Ю; Сабирэянов А А; Попелъ П C

    2011-01-01

    basic unit of β phase-like residual bond structures causes an abnormal change of viscosity in the first heating process; in the subsequent cooling process and the second heating process, the melt reaches a new dynamic equilibrium state, and Al atoms are uniformly distributed in the melt.At this time, the size of Mg-Al average atomic cluster ds and the number of short-range order atoms Ns inside them increase (decrease) monotonically with temperature, and the relationship between viscosity v and size of average atomic clusters ds is expressed as a linear function, i.e., v = v0 + K · ds, which presents a new way for revealing micro-structure change of alloy melt and further understanding the change characteristic of viscosity.

  5. Structures and physicochemical properties of molecular aggregates of lipids

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

  6. Plant Trait-Species Abundance Relationships Vary with Environmental Properties in Subtropical Forests in Eastern China

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

    2013-01-01

    Understanding how plant trait-species abundance relationships change with a range of single and multivariate environmental properties is crucial for explaining species abundance and rarity. In this study, the abundance of 94 woody plant species was examined and related to 15 plant leaf and wood traits at both local and landscape scales involving 31 plots in subtropical forests in eastern China. Further, plant trait-species abundance relationships were related to a range of single and multivar...

  7. Organic bulk heterojunction photovoltaic structures: design, morphology and properties

    Main approaches to the design of organic bulk heterojunction photovoltaic structures are generalized and systematized. Novel photovoltaic materials based on fullerenes, organic dyes and related compounds, graphene, conjugated polymers and dendrimers are considered. The emphasis is placed on correlations between the chemical structure and properties of materials. The effect of morphology of the photoactive layer on the photovoltaic properties of devices is analyzed. Main methods of optimization of the photovoltaic properties are outlined. The bibliography includes 338 references

  8. Formation, structures and properties of whey protein aggregates

    Famelart, Marie-Hélène; Croguennec, Thomas; Guyomarc'H, Fanny; Bouhallab, Said

    2015-01-01

    The native whey proteins have been intensively used in a multitude of food applications due to their high nutritional, biological, and versatile techno-functional properties. The range of applications of whey proteins has further been extended in the last decades by the use of whey protein aggregates offering new techno-functional properties. These properties are directly dependent on the structure of whey protein aggregates, i.e., their size, shape, density, internal structure and surface pr...

  9. Electronic structure and properties of rare earth and actinide intermetallics

    There are 188 contributions, experimental and theoretical, a few on rare earth and actinide elements but mostly on rare earth and actinide intermetallic compounds and alloys. The properties dealt with include 1) crystal structure, 2) magnetic properties and magnetic structure, 3) magnetic phase transformations and valence fluctuations, 4) electrical properties and superconductivity and their temperature, pressure and magnetic field dependence. A few papers deal with crystal growth and novel measuring methods. (G.Q.)

  10. Affine invariant texture analysis based on structural properties

    Zhang, Jianguo; Tan, Tieniu

    2002-01-01

    This paper presents a new texture analysis method based on structural properties. The texture features extracted using this algorithm are invariant to affine transform (including rotation, translation, scaling, and skewing). Affine invariant structural properties are derived based on texel areas. An area-ratio map utilizing these properties is introduced to characterize texture images. Histogram based on this map is constructed for texture classification. Efficiency of this algorithm for affi...

  11. Stress-strain relationship with soil structural parameters of collapse loess

    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.

  12. Foundations of compositional models: structural properties

    Jiroušek, Radim; Kratochvíl, Václav

    2015-01-01

    Roč. 44, č. 1 (2015), s. 2-25. ISSN 0308-1079 R&D Projects: GA ČR GA13-20012S Grant ostatní: GA ČR(CZ) GAP403/12/2175 Institutional support: RVO:67985556 Keywords : multidimensional distribution * conditional independence * composition * semigraphoid properties * running intersection property Subject RIV: BA - General Mathematics Impact factor: 1.637, year: 2014 http://library.utia.cas.cz/separaty/2015/MTR/jirousek-0442412.pdf

  13. Parametric modeling for quantitative analysis of pulmonary structure to function relationships

    Haider, Clifton R.; Bartholmai, Brian J.; Holmes, David R., III; Camp, Jon J.; Robb, Richard A.

    2005-04-01

    While lung anatomy is well understood, pulmonary structure-to-function relationships such as the complex elastic deformation of the lung during respiration are less well documented. Current methods for studying lung anatomy include conventional chest radiography, high-resolution computed tomography (CT scan) and magnetic resonance imaging with polarized gases (MRI scan). Pulmonary physiology can be studied using spirometry or V/Q nuclear medicine tests (V/Q scan). V/Q scanning and MRI scans may demonstrate global and regional function. However, each of these individual imaging methods lacks the ability to provide high-resolution anatomic detail, associated pulmonary mechanics and functional variability of the entire respiratory cycle. Specifically, spirometry provides only a one-dimensional gross estimate of pulmonary function, and V/Q scans have poor spatial resolution, reducing its potential for regional assessment of structure-to-function relationships. We have developed a method which utilizes standard clinical CT scanning to provide data for computation of dynamic anatomic parametric models of the lung during respiration which correlates high-resolution anatomy to underlying physiology. The lungs are segmented from both inspiration and expiration three-dimensional (3D) data sets and transformed into a geometric description of the surface of the lung. Parametric mapping of lung surface deformation then provides a visual and quantitative description of the mechanical properties of the lung. Any alteration in lung mechanics is manifest by alterations in normal deformation of the lung wall. The method produces a high-resolution anatomic and functional composite picture from sparse temporal-spatial methods which quantitatively illustrates detailed anatomic structure to pulmonary function relationships impossible for translational methods to provide.

  14. Structure-rheology relationship in a sheared lamellar fluid

    Jaju, S. J.; Kumaran, V.

    2016-03-01

    The structure-rheology relationship in the shear alignment of a lamellar fluid is studied using a mesoscale model which provides access to the lamellar configurations and the rheology. Based on the equations and free energy functional, the complete set of dimensionless groups that characterize the system are the Reynolds number (ρ γ ˙L2/μ ) , the Schmidt number (μ /ρ D ) , the Ericksen number (μ γ ˙/B ) , the interface sharpness parameter r , the ratio of the viscosities of the hydrophilic and hydrophobic parts μr, and the ratio of the system size and layer spacing (L /λ ) . Here, ρ and μ are the fluid density and average viscosity, γ ˙ is the applied strain rate, D is the coefficient of diffusion, B is the compression modulus, μr is the maximum difference in the viscosity of the hydrophilic and hydrophobic parts divided by the average viscosity, and L is the system size in the cross-stream direction. The lattice Boltzmann method is used to solve the concentration and momentum equations for a two dimensional system of moderate size (L /λ =32 ) and for a low Reynolds number, and the other parameters are systematically varied to examine the qualitative features of the structure and viscosity evolution in different regimes. At low Schmidt numbers where mass diffusion is faster than momentum diffusion, there is fast local formation of randomly aligned domains with "grain boundaries," which are rotated by the shear flow to align along the extensional axis as time increases. This configuration offers a high resistance to flow, and the layers do not align in the flow direction even after 1000 strain units, resulting in a viscosity higher than that for an aligned lamellar phase. At high Schmidt numbers where momentum diffusion is fast, the shear flow disrupts layers before they are fully formed by diffusion, and alignment takes place by the breakage and reformation of layers by shear, resulting in defects (edge dislocations) embedded in a background of

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

    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.

  16. Plant Trait-Species Abundance Relationships Vary with Environmental Properties in Subtropical Forests in Eastern China

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

    2013-01-01

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

  17. Properties of carbon deposits on tungsten nano-structure

    C deposition characteristics on W nano-structure by two different deposition methods are investigated to study C deposition mechanisms on W nano-structure and its characteristics. The two methods were as follows: irradiation by mixed D and C ion beam, and deposition by magnetron sputtering. Differences on deposition condition such as deposition temperature, incident species and energy affected properties of C deposits. Structure of C deposits was investigated by SEM and Raman spectroscopy. D retention properties were investigated by thermal desorption spectroscopy. It was found that C deposits on nano-structured surface have low internal stress and porous structure compared with C deposits on flat surfaces. Increase of CD4 release from C deposition layers on nano-structured surface was investigated by TDS. These results showed the effects of nano-structure on structure and thermal desorption properties of C deposits

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

    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)

  19. Intellectual Property and Market Structure in Agriculture

    Rausser, Gordon C.; Scotchmer, suzanne; Simon, Leo K.

    1999-01-01

    In the past several years, the seed industry worldwide has been dramatically restructured, mostly through mergers and acquisitions. We argue that the restructuring has been technologically driven, and has also resulted in the transformation of several chemical conglomerates into life-sciences firms. We discuss why the restructuring has mostly occurred through mergers rather than contractual relationships such as licensing, and investigate its efficiency implications, both as it concerns antic...

  20. Quantitative structure-chromatographic retention relationship for polycyclic aromatic sulfur heterocycles.

    Xu, Hui-Ying; Zou, Jian-Wei; Jiang, Yong-Jun; Hu, Gui-Xiang; Yu, Qing-Sen

    2008-07-11

    Polycyclic aromatic sulfur heterocycles (PASHs) are of concern in petroleum geochemistry and environmental chemistry. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 114 PASHs reported previously at the HF/6-31G* level of theory. A group of 25 statistically based parameters have been extracted. Linear relationships between gas-chromatographic retention index (RI) and the structural descriptors have been established by stepwise linear regression analysis. The result shows that two quantities derived from positive electrostatic potential on molecular surface, V(s)(+) (the average value of the positive electrostatic potentials on molecular surface) and sigma(+)(2) (a measure of dispersion tendency of positive electrostatic potential), together with V(mc) (the molecular volume) and E(HOMO) (the energy of the highest occupied molecular orbital) can be well used to express the quantitative structure-retention relationship (QSRR) of PASHs. Predictive capability of the model has been demonstrated by leave-one-out cross-validation with the cross-validated correlation coefficient (R(CV)) of 0.992. Furthermore, when splitting the 114 PASH samples into calibration and test sets in the ratio of 2:1, a similar treatment yields an equation of almost equal statistical quality and very similar regression coefficients, validating the robustness of our model. Predictions for six PASHs from other source have also been made. The QSRR model established may provide a new powerful method for predicting chromatographic properties of aromatic organosulfur compounds. PMID:18534609

  1. Data mining and machine learning techniques for the identification of mutagenicity inducing substructures and structure activity relationships of noncongeneric compounds

    Helma, Christoph; Cramer, Tobias; Kramer, Stefan; De Raedt, Luc

    2004-01-01

    This paper explores the utility of data mining and machine learning algorithms for the induction of mutagenicity structure-activity relationships (SARs) from noncongeneric data sets. We compare (i) a newly developed algorithm (MOLFEA) for the generation of descriptors (molecular fragments) for noncongeneric compounds with traditional SAR approaches (molecular properties) and (ii) different machine learning algorithms for the induction of SARs from these descriptors. In addition we investigate...

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

    D. L. Kelting; H. L. Allen

    2000-05-01

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

  3. Nanodiamonds: Their Structure and Optical Properties

    Raty, J.-Y.; van Buuren, T.; Galli, G.

    2002-05-14

    Nanometer sized diamond is a constituent of diverse systems ranging from interstellar dusts and meteorites [1] to carbonaceous residues of detonations [2] and diamond-like films [3-5]. Many of the properties of bulk diamond have been well understood for decades, those of nanodiamond are mostly unexplored. We present a combined theoretical and experimental study showing that diamond has unique properties not only as a bulk material but also at the nanoscale, where size reduction and surface reconstruction effects are fundamentally different from those found, e.g. in Si and Ge.

  4. Structure and properties of atomic nanoclusters

    Alonso, Julio A

    2011-01-01

    Atomic clusters are aggregates of atoms containing a few to several thousand atoms. Due to the small size of these pieces of matter, the properties of atomic clusters in general are different from those of the corresponding material in the macroscopic bulk phase. This monograph presents the main developments of atomic clusters and the current status of the field. The book treats different types of clusters with very different properties: clusters in which the atoms or molecules are tied by weak van der Waals interactions, metallic clusters, clusters of ionic materials, and network clusters mad

  5. Structure, reactivity, and biological properties of hidantoines

    Hydantoin (imidazolidine-2,4-dione) is a 2,4-diketotetrahydroimidazole discovered by Baeyer in 1861. Thiohydantoins and derivatives were prepared, having chemical properties similar to the corresponding carbonyl compounds. Some biological activities (antimicrobial, anticonvulsant, schistosomicidal) are attributed to the chemical reactivity and consequent affinity of hydantoinic rings towards biomacromolecules. Therefore, knowledge about the chemistry of hydantoins has increased enormously. In this review, we present important aspects such as reactivity of hydantoins, acidity of hydantoins, spectroscopy and crystallographic properties, and biological activities of hydantoin and its derivatives. (author)

  6. Structure and Properties of Polysaccharide Based BioPolymer Gels

    Prud'Homme, Robert K.

    2000-03-01

    Nature uses the pyranose ring as the basic building unit for a wideclass of biopolymers. Because of their biological origin these biopolymers naturally find application as food additives, rheology modifiers. These polymers range from being rigid skeletal material, such as cellulose that resist dissolution in water, to water soluble polymers, such as guar or carrageenan. The flexibility of the basic pyranose ring structure to provide materials with such a wide range of properties comes from the specific interactions that can be engineered by nature into the structure. We will present several examples of specific interactions for these systems: hydrogen bonding, hydrophobic interactions, and specific ion interactions. The relationship between molecular interations and rheology will be emphasized. Hydrogen bonding mediated by steric interference is used to control of solubility of starch and the rheology of guar gels. A more interesting example is the hydrogen bonding induced by chemical modification in konjac glucomannan that results in a gel that melts upon cooling. Hydrogen bonding interactions in xanthan lead to gel formation at very low polymer concentrations which is a result of the fine tuning of the polymer persistence length and total contour length. Given the function of xanthan in nature its molecular architecture has been optimized. Hydrophobic interactions in methylcellulose show a reverse temperature dependence arising from solution entropy. Carrageenan gelation upon the addition of specific cations will be addressed to show the interplay of polymer secondary structure on chemical reactivity. And finally the cis-hydroxyls on galactomannans permit crosslinking by a variety of metal ions some of which lead to "living gels" and some of which lead to permanently crosslinked networks.

  7. On some fundamental properties of structural topology optimization problems

    Stolpe, Mathias

    2010-01-01

    We study some fundamental mathematical properties of discretized structural topology optimization problems. Either compliance is minimized with an upper bound on the volume of the structure, or volume is minimized with an upper bound on the compliance. The design variables are either continuous o...... presented examples can be used as teaching material in graduate and undergraduate courses on structural topology optimization.......We study some fundamental mathematical properties of discretized structural topology optimization problems. Either compliance is minimized with an upper bound on the volume of the structure, or volume is minimized with an upper bound on the compliance. The design variables are either continuous or...

  8. Structure and properties of "nematically ordered" aerogels

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

    2015-04-01

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

  9. Properties of complements in the lattice of convergence structures

    C. V. Riecke

    1980-01-01

    Relative complements and differences are investigated for several convergence structure lattices, especially the lattices of Kent convergence structures and the lattice of pretopologies. Convergence space properties preserved by relative complementation are studied. Mappings of some convergence structure lattices into related lattices of lattice homomorphisms are considered.

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

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

    2014-01-01

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

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

    T. K. Das

    2014-01-01

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

  12. Quantitative structure-retention relationships of flavonoids unraveled by immobilized artificial membrane chromatography.

    Santoro, Adriana Leandra; Carrilho, Emanuel; Lanças, Fernando Mauro; Montanari, Carlos Alberto

    2016-06-10

    The pharmacokinetic properties of flavonoids with differing degrees of lipophilicity were investigated using immobilized artificial membranes (IAMs) as the stationary phase in high performance liquid chromatography (HPLC). For each flavonoid compound, we investigated whether the type of column used affected the correlation between the retention factors and the calculated octanol/water partition (log Poct). Three-dimensional (3D) molecular descriptors were calculated from the molecular structure of each compound using i) VolSurf software, ii) the GRID method (computational procedure for determining energetically favorable binding sites in molecules of known structure using a probe for calculating the 3D molecular interaction fields, between the probe and the molecule), and iii) the relationship between partition and molecular structure, analyzed in terms of physicochemical descriptors. The VolSurf built-in Caco-2 model was used to estimate compound permeability. The extent to which the datasets obtained from different columns differ both from each other and from both the calculated log Poct and the predicted permeability in Caco-2 cells was examined by principal component analysis (PCA). The immobilized membrane partition coefficients (kIAM) were analyzed using molecular descriptors in partial least square regression (PLS) and a quantitative structure-retention relationship was generated for the chromatographic retention in the cholesterol column. The cholesterol column provided the best correlation with the permeability predicted by the Caco-2 cell model and a good fit model with great prediction power was obtained for its retention data (R(2)=0.96 and Q(2)=0.85 with four latent variables). PMID:26916828

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

    Vemuri, Venkata Rama Sesha Ravi Kumar

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

  14. Structure-Fluorescence Relationships in Antimicrobial Fluoroquinolones (AMFQs)

    Ana P. Vilches; Nieto, Marcelo J.; María R. Mazzieri; Manzo, Ruben H.

    2000-01-01

    The analysis of fluorescence spectra of a set of structurally related AMFQ let to identify the effects of structural changes and the presence of electric charge generated by acid-base reaction on the emission spectra.

  15. Psychometric properties of the network relationship inventory-social provision version in Chinese youth.

    Wang, Jennifer M

    2014-12-01

    Given the lack of psychometric research on friendship measures in non-Western countries, this study examined the psychometric properties of the Chinese version of the network relationship inventory-social provision version (NRI-SPV-C) in a sample of 200 young adolescents living in China (91 boys; M age = 13.21 years). Results from confirmatory factor analysis demonstrated that a hierarchical structure model with two second-order factors (Social Support, Negative Interactions) and nine first-order factors (Companionship, Intimacy, Instrumental Aid, Nurturance, Affection, Admiration, Reliable Alliance, Conflict, and Antagonism) was the best-fitting model. High internal consistency and high construct reliability were found for all factors. Girls reported higher levels of Social Support compared with boys, though no gender differences emerged for Negative Interactions. Social Support was positively associated with youth's friendship satisfaction (Satisfaction), whereas Negative Interactions was negatively associated with Satisfaction. Findings suggest the NRI-SPV-C may be a fruitful measure for assessing youth's friendship quality in China. PMID:24481946

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

    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.

  17. Structure sensitive properties of KTP-type crystals

    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.

  18. Processing-microstructure-properties relationships in small-particle plasma-sprayed ceramic coatings

    Mawdsley, Jennifer Renee

    The objective of this study was to determine processing-microstructure-properties relationships for small-particle plasma-sprayed (SPPS) ceramic coatings. Plasma-sprayed yttria partially-stabilized zirconia (YSZ) coatings, which are used to protect superalloys from heat and the environment in turbine engines, and plasma-sprayed alumina coatings, which are being investigated as a potential replacement for chrome in corrosion protection applications, were fabricated using SPPS technology and their microstructure and pertinent properties were examined. The properties of plasma-sprayed YSZ and alumina coatings were investigated with designed experiments. The parameters varied include power, spray distance, total plasma gas flow, percent hydrogen in the plasma gas, injector angle, injector offset and carrier gas flow. The variations in thermal diffusivity, thermal conductivity, elastic modulus, and hardness for the YSZ SPPS coatings were found to correlate to the variations in density, which were related to the processing variables. It was found that surface roughness was related to the amount of splashing and debris associated with the single splats. In four-point bending strain tolerance and fatigue tests, the SPPS YSZ coatings showed very little acoustic emission activity, except in the case of tensile fatigue of a coating without network cracks. Small angle X-ray scattering experiments revealed that SPPS YSZ coatings have significantly less submicron intersplat porosity than conventional plasma-sprayed coatings, and that the pore and microcrack scattering area decreases with heat treatment due to the sintering of microcracks and small pores. The SPPS alumina coatings were optimized to produce a coating with excellent corrosion protection capabilities. It was found that the hardest SPPS alumina coatings did not provide the best corrosion protection due to unique porosity defect structures associated with surface bumps in the coatings. The surface bumps were

  19. Antimicrobial profile of some novel keto esters: Synthesis, crystal structures and structure-activity relationship studies.

    Khan, Imtiaz; Saeed, Aamer; Arshad, Mohammad Ifzan; White, Jonathan Michael

    2016-01-01

    Rapid increase in bacterial resistance has become a major public concern by escalating alongside a lack of development of new anti-infective drugs. Novel remedies in the battle against multidrug-resistant bacterial strains are urgently needed. So, in this context, the present work is towards the investigation of antimicrobial efficacy of some novel keto ester derivatives, which are prepared by the condensation of substituted benzoic acids with various substituted phenacyl bromides in dimethylformamide at room temperature using triethylamine as a catalyst. The structural build-up of the target compounds was accomplished by spectroscopic techniques including FTIR, (1)H and (13)C NMR spectroscopy and mass spectrometry. The purity of the synthesized compounds was ascertained by elemental analysis. The molecular structures of compounds (4b) and (4l) were established by X-ray crystallographic analysis. The prepared analogues were evaluated for their antimicrobial activity against Gram-positive (Staphylococcus aureus, Micrococcus leuteus) and Gram-negative (Pseudomonas picketti, Salmonella setuball) bacteria and two fungal pathogenic strains (Aspergillus niger, Aspergillus flavus), respectively. Among the screened derivatives, several compounds were found to possess significant activity but (4b) and (4l) turned out to be lead molecules with remarkable antimicrobial efficacy. The structure-activity relationship analysis of this study also revealed that structural modifications on the basic skeleton affected the antimicrobial activity of the synthesized compounds. PMID:26826838

  20. Fiber: composition, structures, and functional properties.

    Sims, Ian M; Monro, John A

    2013-01-01

    Kiwifruit dietary fiber consists of cell-wall polysaccharides that are typical of the cell walls of many dicotyledonous fruits, being composed of pectic polysaccharides, hemicelluloses, and cellulose. The kiwifruit pectic polysaccharides consist of homo- and rhamnogalacturonans with various neutral, (arabino)-galactan side chains, while the hemicelluloses are mostly xyloglucan and xylan. The proportions of pectic polysaccharide, hemicellulose, and cellulose in both green 'Hayward' and 'Zespri® Gold' are similar and are little affected by in vitro exposure to gastric and small intestinal digestion. The hydration properties of the kiwifruit-swelling and water retention capacity-are also unaffected by foregut digestion, indicating that the functional properties of kiwifruit fiber survive in the foregut. However, in the hindgut, kiwifruit fiber is fermented, but whole kiwifruit consumed in association with slowly fermented fiber leads to distal displacement of fermentation, indicating that hindgut benefits of kiwifruit may result from its interaction with other dietary sources of fiber. PMID:23394983

  1. Preparation and structural properties of Graphene

    Graphene, as an ideal realization of two-dimensional crystals, has a promising future due to its unique electronic and physical properties. Many methods have been exploited to prepare high quality Graphene. Three main methods are reviewed, including the thermal decomposition of SiC (carbide) crystal surfaces, catalytic decomposition of hydrocarbon molecules on noble metal crystal surfaces, and chemically modified dispersion/reduction. The characteristics, recent development, and application prospects of each method are also discussed. (authors)

  2. Approaches to tailoring the structure and properties of polyethylene

    Li Pi Shan, Colin

    Alternative methods to control the molecular weight and short chain branching distribution of polyethylene were investigated. The ability to produce polyolefins with multimodal microstructural distributions using single catalyst/single reactor set-up is very attractive and could, in principle, be used to produce polyolefin resins with advanced molecular architecture. In this thesis, resins with controlled microstructures were produced, characterized and properties tested in order to develop a better understanding of polymerization structure-property relationships. Copolymerizations of ethylene and 1-hexene were carried out with an in-situ supported metallocene catalyst. Copolymers were produced with different alkylaluminum activators and the effect on molecular weight and short chain branching distributions was examined. It was found that different activator types produce polymer with unimodal and narrow molecular weight distributions but with very different short chain branching distributions. Each activator exhibits unique comonomer incorporation characteristics to produce bimodal short chain branching distributions with the use of a single activator. To further investigate the capabilities of this in-situ supported catalyst system, an experimental design was carried out to study the effect of polymerization conditions on the catalyst activity and microstructure of poly(ehhylene- co-1-octene). The parameters investigated were: polymerization temperature, monomer pressure, chain transfer to hydrogen, comonomer/ethylene feed ratio and concentration of alkylaluminum. The effect of each parameter on the catalyst activity, comonomer incorporation and molecular weight distribution was investigated. To examine the effect of these broad short chain branching distributions on the polymer properties, a series of poly(ethylene-co-1-hexene) resins with very distinct, and in some cases bimodal crystalline distributions, were synthesized. It was found that the tensile

  3. MPOD: A Material Property Open Database linked to structural information

    Inspired by the Crystallography Open Database (COD), the Material Properties Open Database (MPOD) was given birth. MPOD aims at collecting and making publicly available at no charge tensorial properties (including scalar properties) of phases and linking such properties to structural information of the COD when available. MPOD files are written with the STAR file syntax, used and developed for the Crystallographic Information Files. A dictionary containing new definitions has been written according to the Dictionary Definition Language 1, although some tricks were adopted to allow for multiple entries still avoiding ambiguousness. The initial set includes mechanical properties, elastic stiffness and compliance, internal friction; electrical properties, resistivity, dielectric permittivity and stiffness, thermodynamic properties, heat capacity, thermal conductivity, diffusivity and expansion; electromechanical properties, piezoelectricity, electrostriction, electromechanical coupling; optical properties; piezooptic and photoelastic properties; superconducting properties, critical fields, penetration and coherence lengths. Properties are reported in MPOD files where the original published paper containing the data is cited and structural and experimental information is also given. One MPOD file contains information relative to only one publication and one phase. The files and the information contained therein can also be consulted on-line at (http://www.materialproperties.org).

  4. Relationship structure-antioxidant activity of hindered phenolic compounds

    Weng, X. C.

    2014-12-01

    Full Text Available The relationship between the structure and the antioxidant activity of 21 hindered phenolic compounds was investigated by Rancimat and DPPH· tests. 3-tert-butyl-5-methylbenzene-1,2-diol is the strongest antioxidant in the Rancimat test but not in the DPPH· test because its two hydroxyl groups have very strong steric synergy. 2,6-Ditert-butyl-4-hydroxy-methylphenol exhibits a strong antioxidant activity as 2,6-ditertbutyl- 4-methoxyphenol does in lard. 2,6-Ditert-butyl-4- hydroxy-methylphenol also exhibits stronger activity than 2-tert-butyl-4- methoxyphenol. The methylene of 2,6-ditert-butyl-4-hydroxy-methylphenol can provide a hydrogen atom to active free radicals like a phenolic hydroxyl group does because it is greatly activated by both the aromatic ring and hydroxyl group. Five factors affect the antioxidant activities of the phenolic compounds: how stable the phenolic compound free radicals are after providing hydrogen atoms; how many hy drogen atoms each of the phenolic compounds can provide; how fast the phenolic compounds provide hydrogen atoms; how easily the phenolic compound free radicals can combine with more active free radicals, and whether or not a new antioxidant can form after the phenolic compound provides hydrogen atoms.La relación entre estructura y la actividad antioxidante de 21 compuestos fenólicos con impedimentos estéricos fue investigado mediante ensayos con Rancimat y DPPH·. El 3-terc-butil-5-metilbenceno-1,2-diol es el antioxidante más potente en los ensayos mediante Rancimat pero no mediante ensayos con DPPH·, porque sus dos grupos hidroxilo tienen una fuerte sinergia estérica. El 2,6-Di-terc-butil-4-hidroxi-metil-fenol mostró una actividad antioxidante tan fuerte como el 2,6-di-ter-butil-4-metoxifenol en ensayos con manteca de cerdo. El 2,6-di-terc-butil-4-hidroxi-metilfenol también mostró una actividad más fuerte que el 2-terc-butil-4-metoxifenol. El grupo metileno del 2,6-di-ter-butil-4-hidroxi

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

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

  6. Structural properties of high Tc -superconductors

    Different diffraction methods (single crystal and powder investigations by X-rays and neutrons, electron diffraction) are combined with high resolution electron microscopy in order to study the real structure of YBa2Cu3-δ07-y. The phase transition at about y = 6.35 between the orthorhombic modification (y > 6.35) and the tetragonal structure of the YBa2Cu3O6 type is related to a strongly reduced size of the microdomains. Mixed systems have been studied where Cu is partially substituted by Fe, Ni and Zn. Similar diffraction studies on the (La1-xSrx)2CuO4-δ family show a more simple crystal structure of K2NiF4 type with only one Cu site, which seems to be always fully occupied

  7. Structure and Frictional Properties of Colloid Gel

    Masayuki Tokita

    2014-01-01

    Polymer gels are known to be opaque when the preparation conditions, such as the reaction temperature and the composition, are changed. The increase of the opaqueness of the gel suggests strongly the change of network structure. Here, we are going to review the recent studies on the structure and the frictional study of the opaque poly(acrylamide) gel. The results indicate that the opaque poly(acrylamide) gel consists of the fractal aggregate of the colloidal particles of sub-micrometer in si...

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

    Sławomir Sagan

    2013-02-01

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

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

    Sierpowska, J [Department of Applied Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Toeyraes, J [Department of Applied Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Hakulinen, M A [Department of Surgery, Kuopio University Hospital, POB 1777, 70211 Kuopio (Finland); Saarakkala, S [Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Kuopio, POB 1777, 70211 Kuopio (Finland); Jurvelin, J S [Department of Applied Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland); Lappalainen, R [Department of Applied Physics, University of Kuopio, POB 1627, 70211 Kuopio (Finland)

    2003-03-21

    Interrelationships of trabecular bone electrical and dielectric properties with mechanical characteristics and density are poorly known. While electrical stimulation is used for healing fractures, better understanding of these relations has clinical importance. Furthermore, earlier studies have suggested that bone electrical and dielectric properties depend on the bone density and could, therefore, be used to predict bone strength. To clarify these issues, volumetric bone mineral density (BMD{sub vol}), electrical and dielectric as well as mechanical properties were determined from 40 cylindrical plugs of bovine trabecular bone. Phase angle, relative permittivity, loss factor and conductivity of wet bovine trabecular bone were correlated with Young's modulus, yield stress, ultimate strength, resilience and BMD{sub vol}. The reproducibility of in vitro electrical and dielectric measurements was excellent (standardized coefficient of variation less than 1%, for all parameters), especially at frequencies higher than 1 kHz. Correlations of electrical and dielectric parameters with the bone mechanical properties or density were frequency-dependent. The relative permittivity showed the strongest linear correlations with mechanical parameters (r > 0.547, p < 0.01, n = 40, at 50 kHz) and with BMD{sub vol} (r 0.866, p < 0.01, n = 40, at 50 kHz). In general, linear correlations between relative permittivity and mechanical properties or BMD{sub vol} were highest at frequencies over 6 kHz. In addition, a significant site-dependent variation of electrical and dielectric characteristics, mechanical properties and BMD{sub vol} was revealed in bovine femur (p < 0.05, Kruskall-Wallis H-test). Based on the present results, we conclude that the measurement of electrical and dielectric properties provides quantitative information that is related to bone quantity and quality.

  10. Structure and Properties of Compressed Borate Glasses

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

    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...

  11. Magnetic structures and properties of vanadium diiodide.

    Kuindersma, S. R.; Haas, C.; Sanchez, J. P.; Al, R.

    1979-01-01

    Single-crystal measurements of the magnetic susceptibilities of VI2 show an anomaly at a crit. temp. of ∼14 K. This anomaly can be ascribed to a magnetic phase transition from a 120° structure to a collinear arrangement of the spins with a magnetic unit cell amagn = a√3, bmagn = 2 a and cmagn = 2 c.

  12. New membrane structures with proton conducting properties

    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 for...... [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...

  13. Molecular structure based property modeling: Development/ improvement of property models through a systematic property-data-model analysis

    Hukkerikar, Amol Shivajirao; Sarup, Bent; Sin, Gürkan;

    2013-01-01

    models. To make the property-data-model analysis fast and efficient, an approach based on the “molecular structure similarity criteria” to identify molecules (mono-functional, bi-functional, etc.) containing specified set of structural parameters (that is, groups) is employed. The method has been applied......The objective of this work is to develop a method for performing property-data-model analysis so that efficient use of knowledge of properties could be made in the development/improvement of property prediction models. The method includes: (i) analysis of property data and its consistency check...... to a wide range of properties of pure compounds. In this work, however, the application of the method is illustrated for the property modeling of normal melting point, enthalpy of fusion, enthalpy of formation, and critical temperature. For all the properties listed above, it has been possible to achieve...

  14. Application of Information Processing Theory on the inter-relationship of organizational culture and organizational structure

    Li, YIH; Fellows, RF; Liu, AMM

    2008-01-01

    A conceptual model of the inter-relationship between organizational culture and organizational structure has been formulated. However, it is still unable to explain the direction of interaction of organizational culture and organizational structure in real day-to-day operation. This paper explains this relationship through the application of Information-Processing Theory. It has been established that, on one hand, organizational structure modifies organizational culture and, on the other hand...

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

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

    2015-01-01

    The relationship between protein three-dimensional structure and function is essential in determining mechanism. Unfortunately, most techniques do not provide a direct measurement of this relationship. Structural data are usually limited to static pictures and function must be inferred. Conversely, functional assays usually provide little information on structural conformation. We developed a single-molecule technique combining optical tweezers and fluorescence microscopy that allows for both...

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

    Sierpowska, J.; Töyräs, J.; Hakulinen, M. A.; Saarakkala, S.; Jurvelin, J. S.; Lappalainen, R.

    2003-03-01

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

  17. Thermodynamical properties and thermoelastic coupling of complex macroscopic structure

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

  18. Quantum chemistry research structure and electronic properties of peroxides

    Grytselyak, Tymofiy; Shchodryi, Volodymyr; Dutka, Volodymyr; Kovalskyi, Yaroslav

    2013-01-01

    We have calculated the optimal structure, electronic properties and heat of formation (?fH? ) peroxide compounds with the help of semiempirical quantum chemical methods. Theoretically calculated values well coincide with the values found from thermochemical experiments.

  19. The radiation influence on physical properties in photosensitive structure

    It was shown experimentally that in photosensitive structures with gallium arsenides - cadmium sulfides heterojunction the physical properties after γ-radiation exposure could be changed essentially and their photoelectrical characteristics improved. (author). 3 refs.; 2 figs

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

    Rekvig, Live

    2004-01-01

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

  1. Fused aromatic thienopyrazines: structure, properties and function

    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.

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

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

  3. Structural, electronic, and transport properties of silicon nanowires

    Rurali, Riccardo

    2009-01-01

    In this paper we review the theory of silicon nanowires. We focus on nanowires with diameters below 10 nm, where quantum effects become important and the properties diverge significantly from those of bulk silicon. These wires can be efficiently treated within electronic structure simulation methods and will be among the most important functional blocks of future nanoelectronic devices. Firstly, we review the structural properties of silicon nanowires, emphasizing the close connection between...

  4. Structure and properties of Titanium for dental implants

    GREGER, Miroslav; Černý, Martin; Kander, Ladislav; Kliber, Jiří

    2009-01-01

    This paper describes manufacture of nano-structural titanium, its structure and properties. Nano-titanium has higher specific strength properties than ordinary (coarse-grained) titanium. Nano-titanium was produced by the equal-channel angular pressing (ETAP) process. The research it self was focused on physical base of strengthening and softening processes and developments occurring at the grain boundaries during the ECAP process at half-hot temperature. Strength of nano-titanium ...

  5. Mechanical properties along interfaces of bonded structures in fusion reactors

    Proper assessment of the mechanical properties along interfaces of bonded structures currently used in many fusion reactor designs is essential to compare the different fabrication techniques. A Mechanical Properties Microprobe (MPM) was used to measure hardness and Young's modules along the interfaces of Be/Cu bonded structure. The MPM was able to distinguish different fabrication techniques by a direct measurement of the hardness, Young's modules, and H/E2 which reflects the ability of deformation of the interfacial region

  6. Structural and electronic properties of sodium nanoclusters

    Perez, Luis A.; Reyes-Nava, Juan A.; Garzon, Ignacio L.

    2006-03-01

    Recent advances on mass selection of sodium nanoclusters and their characterization by photoemission electron spectroscopy [1] have given useful data for a variety of clusters sizes. These data may lead to assignments of the relevant structures by comparing the measured photoelectron spectra (PES) with the electronic density of states (DOS) obtained from DFT calculations. In this work, the lowest energy structures modeled by the many-body Gupta potential, are obtained by using molecular dynamics simulations for Nan (n= 178, 204, 271, 298-300, 309). DFT calculations were then performed for neutral, positively- and negatively-charged Nan clusters. A comparison between the DOS of clusters of the same size but different charge will be presented, as well as between the available experimental PES and the theoretical obtained DOS.[1] H. Haberland, T. Hippler, J. Donges, O. Kostko, M. Schmidt, B. von Issendorff, Phys. Rev. Lett. 94, 035701 (2005).

  7. Organogels thermodynamics, structure, solvent role, and properties

    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 ...

  8. Calculation of structurally related properties of bulk and surface Si

    The self-consistent pseudopotential method is applied to study the bulk and surface structurally related properties of Si. Equilibrium configurations are determined by minimizing the total energy of the system; the calculated bulk properties and the surface relaxation of Si are found to be in good agreement with experiment. The surface energy and the surface reconstruction of Si are briefly discussed

  9. The structural and magnetic properties of holmium/scandium superlattices

    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...

  10. Computer-aided visualization of database structural relationships

    Interactive computer graphic displays can be extremely useful in augmenting understandability of data structures. In complexly interrelated domains such as bibliographic thesauri and energy information systems, node and link displays represent one such tool. This paper presents examples of data structure representations found useful in these domains and discusses some of their generalizable components. 2 figures

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

    Ana-Maria Lacrămă

    2007-05-01

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

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

    Mančić Lidija T.

    2004-01-01

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

  13. pi-Stacks Based on Self-Assembled Perylene Bisimides : Structural, Optical, and Electronic Properties

    Chen, Zhijian

    2006-01-01

    As a traditional industrial pigment, perylene bisimide (PBI) dyes have found wide-spread applications. In addition, PBI dyes have been considered as versatile and promising functional materials for organic-based electronic and optic devices, such as transistors and solar cells. For these novel demands, the control of self-organization of this type of dye and the investigation of the relationship between the supramolecular structure and the relevant optical and electronic properties is of grea...

  14. Structural Properties and Phonon dispertion of NACl

    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.

  15. Radiation change of structural isotropic graphite properties

    Samples of three kinds of isotropic graphite properties by different density and grain size were irradiated to the neutron fluence (1.7 - 2.8) x 1026 m-2 (E > 0.18 MeV) at 360 - 400 Deg C at the BOR-60 reactor. Changing sizes, specific electric resistance, temperature coefficient of linear expansion, Young modulus were investigated following irradiation. It is established that the increase of density in the 1.67 - 1.76 g/cm3 range causes growth of maximum rate and deep of the volume shrinkage of the isotropic fine graphite. Equation approximating temperature dependence of the critical neutron fluence in the 380 - 780 Deg C range is suggested for the investigated graphite samples

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

    Linear free energy relationships for trivalent cations with crystalline M2O3 and, M(OH)3 phases of lanthanides and actinides were developed from known thermodynamic properties of the aqueous trivalent cations, modifying the Sverjensky and Molling equation. The linear free energy relationship for trivalent cations is as ΔGf,MvX0=aMvXΔGn,M3+0+bMvX+βMvXrM3+, where the coefficients aMvX, bMvX, and βMvX characterize a particular structural family of MvX, rM3+ is the ionic radius of M3+ cation, ΔGf,MvX0 is the standard Gibbs free energy of formation of MvX and ΔGn,M3+0 is the standard non-solvation free energy of the cation. The coefficients for the oxide family are: aMvX=0.2705, bMvX=-1984.75 (kJ/mol), and βMvX=197.24 (kJ/molnm). The coefficients for the hydroxide family are: aMvX=0.1587, bMvX=-1474.09 (kJ/mol), and βMvX=791.70 (kJ/molnm).

  17. Study of transport properties of bodies with a perovskite structure: application to the MgSiO3 perovskite

    After some recalls on transport in ionic solids (Nernst-Einstein relationship, variation of ionic conductivity, hybrid conduction, fast ionic conduction), this research thesis presents the physical properties of perovskites and more particularly the structure and stability of the MgSiO3 perovskite: structure and elastic properties, electric conductivity and transport properties in compounds with a perovskite structure. Then, the author reports the experimental study of the KZnF3 perovskite (a structural analogous of MgSiO3): measurements of electric conductivity under pressure, measurements under atmospheric pressure, result discussion. The next part addresses the numerical simulation of MgSiO3: simulation techniques (generalities on molecular dynamics, model description), investigation of structural, elastic and thermodynamic properties, diffusion properties in quadratic phase

  18. Ab Initio Calculation of Structure and Thermodynamic Properties of Zintl Aluminide SrAl2

    Fu, Zhi-Jian; Jia, Li-Jun; Xia, Ji-Hong; Tang, Ke; Li, Zhao-Hong; Sun, Xiao-Wei; Chen, Qi-Feng

    2015-12-01

    The structural and thermodynamic properties of the orthorhombic and cubic structure SrAl2 at pressure and temperature are investigated by using the ab initio plane-wave pseudopotential density functional theory methodwithin 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 SrAl2 are calculated by the quasi-harmonic Debye model. The pressure-volume relationship and the variations inthe thermal expansion α are obtained systematically in the pressure and temperature ranges of 0-5 GPa and 0-500 K, respectively.

  19. Psychometric properties of the Polish adaptation of the Adult Sibling Relationship Questionnaire (ASRQ)

    Wałęcka-Matyja, Katarzyna

    2014-01-01

    Background. Polish studies have not been focused on the method enabling a reliable and valid measure of the psychological attributes of sibling relationships in the period of adulthood. Aim. The aim of this study was to determine the psychometric properties of the Polish adaptation of the Adult Sibling Relationship Questionnaire (ASRQ). Methods. The study included 406 students of different majors of the University of Łódź and the Łódź University of Technology. In the surveyed group, 58....

  20. Structural and Optical Properties and Emerging Applications of Metal Nanomaterials

    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.