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Sample records for deformed gum metal

  1. Deformation Mechanisms of Gum Metals Under Nanoindentation

    Science.gov (United States)

    Sankaran, Rohini Priya

    Gum Metal is a set of multi-component beta-Ti alloys designed and developed by Toyota Central R&D Labs in 2003 to have a nearly zero shear modulus in the direction. After significant amounts of cold-work (>90%), these alloys were found to have yield strengths at a significant fraction of the predicted ideal strengths and exhibited very little work hardening. It has been speculated that this mechanical behavior may be realized through an ideal shear mechanism as opposed to conventional plastic deformation mechanisms, such as slip, and that such a mechanism may be realized through a defect structure termed "nanodisturbance". It is furthermore theorized that for near ideal strength to be attained, dislocations need to be pinned at sufficiently high stresses. It is the search for these defects and pinning points that motivates the present study. However, the mechanism of plastic deformation and the true origin of specific defect structures unique to gum metals is still controversial, mainly due to the complexity of the beta-Ti alloy system and the heavily distorted lattice exhibited in cold worked gum metals, rendering interpretation of images difficult. Accordingly, the first aim of this study is to clarify the starting as-received microstructures of gum metal alloys through conventional transmission electron microscopy (TEM) and aberration-corrected high resolution scanning transmission electron microscopy with high-angle annular dark field detector (HAADF-HRSTEM) imaging. To elucidate the effects of beta-stability and starting microstructure on the deformation behavior of gum metals and thus to provide adequate context for potentially novel deformation structures, we investigate three alloy conditions: gum metal that has undergone solution heat treatment (STGM), gum metal that has been heavily cold worked (CWGM), and a solution treated alloy of nominal gum metal composition, but leaner in beta-stabilizing content (ST Ref-1). In order to directly relate observed

  2. Deformation in nanocrystalline metals

    OpenAIRE

    Helena Van Swygenhoven; Julia R. Weertman

    2006-01-01

    It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic...

  3. Deformation in nanocrystalline metals

    Directory of Open Access Journals (Sweden)

    Helena Van Swygenhoven

    2006-05-01

    Full Text Available It is now possible to synthesize polycrystalline metals made up of grains that average less than 100 nm in size. Such nanocrystalline metals contain a significant volume fraction of interfacial regions separated by nearly perfect crystals. The small sizes involved limit the conventional operation of dislocation sources and thus a fundamental question arises: how do these materials deform plastically? We review the current views on deformation mechanisms in nanocrystalline, face-centered cubic metals based on insights gained by atomistic computer simulations. These insights are discussed with reference to recent striking experimental observations that can be compared with predictions made by the simulations.

  4. Plastic Deformation of Metal Surfaces

    DEFF Research Database (Denmark)

    Hansen, Niels; Zhang, Xiaodan; Huang, Xiaoxu

    2013-01-01

    parameters by TEM and EBSD and apply strength-structural relationships established for the bulk metal deformed to high strains. This technique has been applied to steel deformed by high energy shot peening and a calculated stress gradient at or near the surface has been successfully validated by hardness......Plastic deformation of metal surfaces by sliding and abrasion between moving parts can be detrimental. However, when the plastic deformation is controlled for example by applying different peening techniques hard surfaces can be produced which can increase the fracture resistance and fatigue life...... of metal components. An optimization of processes and material parameters must be based on a quantification of stress and strain gradients at the surface and in near surface layer where the structural scale can reach few tens of nanometers. For such fine structures it is suggested to quantify structural...

  5. Deformation Behavior of Nanoporous Metals

    Energy Technology Data Exchange (ETDEWEB)

    Biener, J; Hodge, A M; Hamza, A V

    2007-11-28

    of free surfaces can no longer be neglected. As the material becomes more and more constraint by the presence of free surfaces, length scale effects on plasticity become more and more important and bulk properties can no longer be used to describe the material properties. Even the elastic properties may be affected as the reduced coordination of surface atoms and the concomitant redistribution of electrons may soften or stiffen the material. If, and to what extend, such length scale effects control the mechanical behavior of nanoporous materials depends strongly on the material and the characteristic length scale associated with its plastic deformation. For example, ductile materials such as metals which deform via dislocation-mediated processes can be expected to exhibit pronounced length scale effects in the sub-micron regime where free surfaces start to constrain efficient dislocation multiplication. In this chapter we will limit our discussion to our own area of expertise which is the mechanical behavior of nanoporous open-cell gold foams as a typical example of nanoporous metal foams. Throughout this chapter we will review our current understanding of the mechanical properties of nanoporous open-cell foams including both experimental and theoretical studies.

  6. Deformed metals - structure, recrystallisation and strength

    DEFF Research Database (Denmark)

    Hansen, Niels; Juul Jensen, Dorte

    2011-01-01

    It is shown how new discoveries and advanced experimental techniques in the last 25 years have led to paradigm shifts in the analysis of deformation and annealing structures of metals and in the way the strength of deformed samples is related to structural parameters. This is described in three...... sections: structural evolution by grain subdivision, recovery and recrystallisation and strength-structure relationships....

  7. Morphology and Metal Binding Characteristics of a Natural Polymer—Kondagogu (Cochlospermum gossypium Gum

    Directory of Open Access Journals (Sweden)

    R. B. Sashidhar

    2013-07-01

    Full Text Available Kondagogu (Cochlospermum gossypium gum (KG, a natural tree exudate, was investigated for its morphological, adsorption and metal interaction behavior with various toxic heavy metals (Pb, Cd, Ni, Cr and Fe. SEM, AFM and TEM techniques were used to study the morphological changes occurring after metal adsorption onto the biopolymer structure. The degree of biosorption of metals on KG biopolymer surfaces was assessed by small-angle X-ray scattering analysis. EDXA spectrum revealed that the ion-exchange mechanism plays a major role in the binding process between KG and metal ions. The higher electron density observed in the KG-Cd complex suggests that Cd is strongly bound to KG compared to the other metals. This work provides a potential platform for developing a hydrocolloid-based nanogel for bioremediation of environmental contaminants.

  8. Thermostatistical theory of plastic deformation in metals

    NARCIS (Netherlands)

    Galindo Nava, E.I.

    2013-01-01

    This work aims to describe plastic deformation and microstructure evolution of metals at various scales in terms of dislocation behaviour. The theory is based on statistical thermodynamics, where the entropy is proposed to incorporate the possible paths for dislocation motion. Other than estimating

  9. Potentiality of the "Gum Metal" titanium-based alloy for biomedical applications.

    Science.gov (United States)

    Gordin, D M; Ion, R; Vasilescu, C; Drob, S I; Cimpean, A; Gloriant, T

    2014-11-01

    In this study, the "Gum Metal" titanium-based alloy (Ti-23Nb-0.7Ta-2Zr-1.2O) was synthesized by melting and then characterized in order to evaluate its potential for biomedical applications. Thus, the mechanical properties, the corrosion resistance in simulated body fluid and the in vitro cell response were investigated. It was shown that this alloy presents a very high strength, a low Young's modulus and a high recoverable strain by comparison with the titanium alloys currently used in medicine. On the other hand, all electrochemical and corrosion parameters exhibited more favorable values showing a nobler behavior and negligible toxicity in comparison with the commercially pure Ti taken as reference. Furthermore, the biocompatibility tests showed that this alloy induced an excellent response of MC3T3-E1 pre-osteoblasts in terms of attachment, spreading, viability, proliferation and differentiation. Consequently, the "Gum Metal" titanium-based alloy processes useful characteristics for the manufacturing of highly biocompatible medical devices.

  10. Computing elastic anisotropy to discover gum-metal-like structural alloys

    Science.gov (United States)

    Winter, I. S.; de Jong, M.; Asta, M.; Chrzan, D. C.

    2017-08-01

    The computer aided discovery of structural alloys is a burgeoning but still challenging area of research. A primary challenge in the field is to identify computable screening parameters that embody key structural alloy properties. Here, an elastic anisotropy parameter that captures a material's susceptibility to solute solution strengthening is identified. The parameter has many applications in the discovery and optimization of structural materials. As a first example, the parameter is used to identify alloys that might display the super elasticity, super strength, and high ductility of the class of TiNb alloys known as gum metals. In addition, it is noted that the parameter can be used to screen candidate alloys for shape memory response, and potentially aid in the optimization of the mechanical properties of high-entropy alloys.

  11. Bactericidal Activity of Oleo-gum Resins Doped with Metal Oxides

    Directory of Open Access Journals (Sweden)

    MSc Diogo José Horst

    2016-12-01

    Full Text Available This work aimed to evaluate the bactericidal activity of vegetable oil-gum resins (Styrax benzoin, Commiphora mirrha, and Boswellia papyrifera doped with metal oxides (TiO2, P25, MoO3 e Cu2O in nanometric dimension. The in vitro susceptibility of pathogenic Gram-negative bacteria E. coli was accessed. The antibiogram essay was performed using the semi-quantitative method Kirby-Bauer (KB agar diffusion test. The materials obtained were characterized by ultraviolet visible (UV-Vis spectrophotometry, additionally; its morphology was characterized by scanning electron microscopy (SEM. The results show that in most cases the materials present bactericidal activity, thereby inhibiting both planktonic and surface associated growth of this microorganism.

  12. HAADF imaging of the omega (ω) phase in a gum metal-related alloy

    Science.gov (United States)

    Sankaran, R. P.; Ophus, C.; Ozdol, B.; Radmilovic, V. R.; Minor, A. M.; Morris, J. W.

    2014-09-01

    Nanosized precipitates have been observed in a Nb-lean gum metal-related alloy, Ti-20.0Nb-0.6Ta-1.7Zr-1.1O at.% (Ti-31.9Nb-2.0Ta-2.7Zr-0.3O wt.%) using probe-corrected high-resolution scanning transmission electron microscopy with a high-angle annular dark-field detector (HAADF). This characterization yields three distinct atomic motifs and STEM multislice simulations are semi-quantitatively used to verify that each motif can be attributed to the widely observed "athermal" omega phase. However, the presence of chemical ordering cannot be unambiguously ruled out in this system. Data presented here, demonstrate the complexity of interpreting HAADF images of multiphase, multicomponent alloys when complementary experimental data are unavailable.

  13. Deformation mechanisms in nanotwinned metal nanopillars.

    Science.gov (United States)

    Jang, Dongchan; Li, Xiaoyan; Gao, Huajian; Greer, Julia R

    2012-09-01

    Nanotwinned metals are attractive in many applications because they simultaneously demonstrate high strength and high ductility, characteristics that are usually thought to be mutually exclusive. However, most nanotwinned metals are produced in polycrystalline forms and therefore contain randomly oriented twin and grain boundaries making it difficult to determine the origins of their useful mechanical properties. Here, we report the fabrication of arrays of vertically aligned copper nanopillars that contain a very high density of periodic twin boundaries and no grain boundaries or other microstructural features. We use tension experiments, transmission electron microscopy and atomistic simulations to investigate the influence of diameter, twin-boundary spacing and twin-boundary orientation on the mechanical responses of individual nanopillars. We observe a brittle-to-ductile transition in samples with orthogonally oriented twin boundaries as the twin-boundary spacing decreases below a critical value (∼3-4 nm for copper). We also find that nanopillars with slanted twin boundaries deform via shear offsets and significant detwinning. The ability to decouple nanotwins from other microstructural features should lead to an improved understanding of the mechanical properties of nanotwinned metals.

  14. Reduction of Deformations during Welding Metal Wire Mesh with Frames

    Directory of Open Access Journals (Sweden)

    Krawczyk R.

    2016-06-01

    Full Text Available The article presents an issue referring to a reduction of deformation during welding metal wire mesh into the frames. A problem of a possible reduction of deformations was described taking into account characteristics of a construction of a welded element. Technological tests and their results are provided. Technological recommendations relating to the reduction of deformations of the welded element are given.

  15. Bleeding gums

    Science.gov (United States)

    ... periodontal exam. DO NOT use tobacco, since it makes bleeding gums worse. Control gum bleeding by applying pressure directly on the gums with a gauze pad soaked in ice water. If you have been diagnosed with a ...

  16. Structural features of plastic deformation in bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Scudino, S., E-mail: s.scudino@ifw-dresden.de; Shakur Shahabi, H.; Stoica, M.; Kühn, U. [IFW Dresden, Institut für Komplexe Materialien, D-01069 Dresden (Germany); Kaban, I.; Escher, B.; Eckert, J. [IFW Dresden, Institut für Komplexe Materialien, D-01069 Dresden (Germany); TU Dresden, Institut für Werkstoffwissenschaft, D-01062 Dresden (Germany); Vaughan, G. B. M. [European Synchrotron Radiation Facilities ESRF, BP220, 38043 Grenoble (France)

    2015-01-19

    Spatially resolved strain maps of a plastically deformed bulk metallic glass (BMG) have been created by using high-energy X-ray diffraction. The results reveal that plastic deformation creates a spatially heterogeneous atomic arrangement, consisting of strong compressive and tensile strain fields. In addition, significant shear strain is introduced in the samples. The analysis of the eigenvalues and eigenvectors of the strain tensor indicates that considerable structural anisotropy occurs in both the magnitude and direction of the strain. These features are in contrast to the behavior observed in elastically deformed BMGs and represent a distinctive structural sign of plastic deformation in metallic glasses.

  17. Structural refinement and deformation mechanisms in nanostructured metals

    DEFF Research Database (Denmark)

    Lu, K.; Hansen, Niels

    2009-01-01

    Deformation mechanisms in metals deformed to ultrahigh strains are analyzed based on a general pattern of grain subdivision down to structural scales 10 nm. The materials analyzed are medium- to high-stacking fault energy face-centered cubic and body-centered cubic metals with different loading...... conditions. The analysis points to dislocation glide as the dominant deformation mechanism at different length scales supplemented by a limited amount of twinning at the finest scales. With decreasing deformation temperature and increasing strain rate, the contribution of twinning increases...

  18. Microwave induced elastic deformation of a metallic thin film

    CERN Document Server

    Wang, S B

    2013-01-01

    The microwave induced elastic deformation of a metallic thin film is computed numerically and we found that the deformation can be significantly enhanced at resonance. We show that an analytical transmission line model can reproduce the numerical results almost quantitatively and at the same time reveal the underlying physics.

  19. Structural refinement and coarsening in deformed metals

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Xing, Q.

    2005-01-01

    The microstructural refinement by plastic deformation is analysed in terms of key parameters, the spacing between and the misorientation angle across the boundaries subdividing the structure. Coarsening of such structures by annealing is also characterised. For both deformed and annealed structur...

  20. Deformation Wave Hardening of Metallic Materials

    Directory of Open Access Journals (Sweden)

    A.V. Kirichek

    2014-07-01

    Full Text Available The article deals with the machine parts hardening by means of deformation waves generated by the impact system with a waveguide as an intermediary member. The conditions for the efficient use of impact energy for elastoplastic deformation of the processed material and creation of the deep hardened surface layer.

  1. Damage evolution of metallic materials during high temperature plastic deformation

    Institute of Scientific and Technical Information of China (English)

    汪凌云; 刘雪峰; 汤爱涛; 黄光杰

    2002-01-01

    The damage evolution of high temperature plastic deformation of metallic materials was studied by use of continuum damage mechanics (CDM) theory. Based on thermodynamics, on a damage variable D and Zener-Hollomon parameter Z, and on the effective stress concept, a damage evolution model of high temperature plastic deformation was derived and was used to analyze the damage evolution of 1420 Al-Li alloy during high temperature plastic deformation. The model that is verified by tests can also be applied to the materials that are loaded prorata or out of proportion during high temperature plastic deformation. It extends the applied scope of damage mechanics.

  2. The Cyclic Deformation Behavior of Severe Plastic Deformation (SPD Metals and the Influential Factors

    Directory of Open Access Journals (Sweden)

    Charles C. F. Kwan

    2012-02-01

    Full Text Available A deeper understanding of the mechanical behavior of ultra-fine (UF and nanocrystalline (NC grained metals is necessary with the growing interest in using UF and NC grained metals for structural applications. The cyclic deformation response and behavior of UF and NC grained metals is one aspect that has been gaining momentum as a major research topic for the past ten years. Severe Plastic Deformation (SPD materials are often in the spotlight for cyclic deformation studies as they are usually in the form of bulk work pieces and have UF and NC grains. Some well known techniques in the category of SPD processing are High Pressure Torsion (HPT, Equal Channel Angular Pressing (ECAP, and Accumulative Roll-Bonding (ARB. In this report, the literature on the cyclic deformation response and behavior of SPDed metals will be reviewed. The cyclic response of such materials is found to range from cyclic hardening to cyclic softening depending on various factors. Specifically, for SPDed UF grained metals, their behavior has often been associated with the observation of grain coarsening during cycling. Consequently, the many factors that affect the cyclic deformation response of SPDed metals can be summarized into three major aspects: (1 the microstructure stability; (2 the limitation of the cyclic lifespan; and lastly (3 the imposed plastic strain amplitude.

  3. Rheology of Rice Flour Dough with Gum Arabic: Small and Large-Deformation Studies, Sensory Assessment and Modeling.

    Science.gov (United States)

    Shanthilal, J; Bhattacharya, Suvendu

    2015-08-01

    The absence of gluten protein makes the rice flour doughs difficult to handle when flattened/sheeted products are to be prepared. The rheological, sensory and microstructural changes in rice flour doughs having gum Arabic (0% to 5%, w/w) and moisture contents (44% to 50%) were studied for improving the dough handling characteristics. Rheological parameters like storage modulus (G') and complex viscosity (η*) decreased with an increase in moisture content while loss angle (δ) increased. A power-law type equation was suitable to relate angular frequency (ω) with G', G", and η* (0.814 ≤ r ≤ 0.999, P ≤ 0.01). An increase in gum and moisture contents increased δ from 6.9° to 15.5° but decreased the energy required for compression/flattening. The 6-element spring-dashpot model was suitable (r ≥ 0.991, P ≤ 0.01) for creep curves. The sensory panel had the opinion that dough with a low to moderate hardness between 3 and 4, and stickiness of ≤ 3.5 was suitable for the purpose of flattening in relation to the preparation of sheeted/flattened products; the appropriate condition for dough formulation was with the moisture and gum contents of 47.0% to 47.9% and 1.55% to 2.25%, respectively to offer the desirability index between 0.50 and 0.52. The microstructure of the rice flour dough in the absence of gum Arabic appeared to possess loosely bound flour particles. The presence of gum provided a coating on flour particles to yield dough having good cohesive microstructure. © 2015 Institute of Food Technologists®

  4. Gum biopsy

    Science.gov (United States)

    Biopsy - gingiva (gums) ... used to close the opening created for the biopsy. ... to eat for a few hours before the biopsy. ... Risks for this procedure include: Bleeding from the biopsy site Infection of the gums Soreness

  5. Tragacanth gum

    DEFF Research Database (Denmark)

    Meyer, Anne S.; Mikkelsen, Jørn Dalgaard; Gavlighi, Hassan Ahmadi

    2013-01-01

    Tragacanth gum is a plant derived hydrocolloid that has a long history of use in food, pharma, and cosmetics. The gum is mainly produced in the Middle East and permitted for food use in the US and Europe. Tragacanth gum consists of complex, heterogeneous polysaccharides, which contain different h...... of value-added prebiotic compounds for functional foods.......Tragacanth gum is a plant derived hydrocolloid that has a long history of use in food, pharma, and cosmetics. The gum is mainly produced in the Middle East and permitted for food use in the US and Europe. Tragacanth gum consists of complex, heterogeneous polysaccharides, which contain different...... highly substituted pectin-like structural elements. Enzymatically produced low molecular- weight fractions of tragacanth gum exhibit potential prebiotic activity by promoting growth in vitro of Bifidobacterium longum subsp. infantis strains. These findings may lead to new uses of this gum for production...

  6. Gum Disease

    Science.gov (United States)

    ... away from the teeth. This is known as periodontitis (pronounced: pair-ee-oh-don-TY-tus), a more advanced form of gum disease. With periodontitis, gums become weakened and form pockets around the ...

  7. Tragacanth gum

    DEFF Research Database (Denmark)

    Meyer, Anne S.; Mikkelsen, Jørn Dalgaard; Gavlighi, Hassan Ahmadi

    2013-01-01

    Tragacanth gum is a plant derived hydrocolloid that has a long history of use in food, pharma, and cosmetics. The gum is mainly produced in the Middle East and permitted for food use in the US and Europe. Tragacanth gum consists of complex, heterogeneous polysaccharides, which contain different h...... of value-added prebiotic compounds for functional foods....

  8. Hardening by annealing and softening by deformation in nanostructured metals

    DEFF Research Database (Denmark)

    Huang, X.; Hansen, N.; Tsuji, N.

    2006-01-01

    -dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed......We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation....... As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing....

  9. The healing of damage after the plastic deformation of metals

    Directory of Open Access Journals (Sweden)

    S.V. Smirnov

    2013-04-01

    Full Text Available The general regularities of damage healing during the annealing after cold deformation of metal materials are presented in this paper. In categories of damage mechanics the kinetic equations of damage healing during recovery and recrystallization are formulated. Diagrams of damage healing for some metal alloys are presented. The example of use of investigation results for optimization of industrial technology of pipes drawing is presented.

  10. Plastic theory for the multi-crystal metals-From infinitesimal deformation to finite deformation

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Multi-crystal metals have the property of volume conservation in the plastic state. In the infinitesimal deformation plasticity the strain tensor can be split into a deviator part and a volumetric part. The vanishing of the first variant of the strain tensor is equivalent to the volume conservation. Furthermore, the split of the strain into an elastic part and a plastic part is also adopted widely. The flow rule is thus established. These two splits are not confirmed in the finite deformation plasticity. The plasticity criterion and the flow rule are thus facing great challenge. There are various definitions of strain measures in the finite deformation theory. Though the choosing of strain measure is arbitrary in the elastic problem, it is strongly restricted in the plastic problem. By theoretical and experimental studies, it is shown that the logarithmic strain is the only suitable strain measure in the metal forming problem.

  11. Extended Dislocations in Plastically Deformed Metallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Bin Zheng

    2016-05-01

    Full Text Available In the present study, the sawtooth nature of compressive loading of metallic nanoparticles is observed using a molecular dynamics simulation. The atomic structure evolution confirmed that extended dislocations are the main defects split into two asynchronous partial disloca‐ tions, along with stored and released fault energy. This is considered the essence of sawtooth loading. The size of the nanoparticles relative to the equilibrium width of the extended dislocation is discussed to explain the simulation results.

  12. Disorder-Driven Metal-Insulator Transitions in Deformable Lattices

    Science.gov (United States)

    Di Sante, Domenico; Fratini, Simone; Dobrosavljević, Vladimir; Ciuchi, Sergio

    2017-01-01

    We show that, in the presence of a deformable lattice potential, the nature of the disorder-driven metal-insulator transition is fundamentally changed with respect to the noninteracting (Anderson) scenario. For strong disorder, even a modest electron-phonon interaction is found to dramatically renormalize the random potential, opening a mobility gap at the Fermi energy. This process, which reflects disorder-enhanced polaron formation, is here given a microscopic basis by treating the lattice deformations and Anderson localization effects on the same footing. We identify an intermediate "bad insulator" transport regime which displays resistivity values exceeding the Mott-Ioffe-Regel limit and with a negative temperature coefficient, as often observed in strongly disordered metals. Our calculations reveal that this behavior originates from significant temperature-induced rearrangements of electronic states due to enhanced interaction effects close to the disorder-driven metal-insulator transition.

  13. Analytical study for deformability of laminated sheet metal

    Directory of Open Access Journals (Sweden)

    Mohammed H. Serror

    2013-01-01

    Full Text Available While a freestanding high-strength sheet metal subject to tension will rupture at a small strain, it is anticipated that lamination with a ductile sheet metal will retard this instability to an extent that depends on the relative thickness, the relative stiffness, and the hardening exponent of the ductile sheet. This paper presents an analytical study for the deformability of such laminate within the context of necking instability. Laminates of high-strength sheet metal and ductile low-strength sheet metal are studied assuming: (1 sheets are fully bonded; and (2 metals obey the power law material model. The effect of hardening exponent, volume fraction and relative stiffness of the ductile component has been studied. In addition, stability of both uniform and nonuniform deformations has been investigated under plane strain condition. The results have shown the retardation of the high-strength layer instability by lamination with the ductile layer. This has been achieved through controlling the aforementioned key parameters of the ductile component, while the laminate exhibits marked enhancement in strength–ductility combination that is essential for metal forming applications.

  14. Deformation of a ceramic/metal interface at the nanoscale.

    Science.gov (United States)

    Jiang, Lin; Hu, Tao; Yang, Hanry; Zhang, Dalong; Topping, Troy; Lavernia, Enrique J; Schoenung, Julie M

    2016-05-19

    The mechanical response of heterophase interfaces has attracted substantial attention in recent years. Here, we utilized an in situ transmission electron microscopy (TEM) technique to isolate an individual nanoscale ceramic/metal interface and characterize its nanomechanical response. The interface, at which there was a Mg-rich segregation nanolayer between the single crystal ceramic (B4C) and the polycrystalline metal (Al alloy, AA5083), was determined to have a bond strength greater than 1.5 GPa. Bimodal failure and metallic grain rotation occurred in the metallic region, allowing the interface to accommodate a deformation strain of 5.4%. The roles of elemental segregation and nanoscale dimensions on interfacial debonding mechanisms are discussed.

  15. Micromechanical modeling of the deformation of HCP metals

    Energy Technology Data Exchange (ETDEWEB)

    Graff, S. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2008-12-04

    Nowadays, intense research is conducted to understand the relation between microstructural features and mechanical properties of hexagonal close-packed (hcp) metals. Due to their hexagonal structure, hcp metals exhibit mechanical properties such as strong anisotropy, which is more pronounced than for construction metals with cubic crystal structure, and tension/compression asymmetry. Deformation mechanisms in hcp metals, dislocation motion on specific slip systems and activation of twinning, are not yet completely understood. The purpose of this work is to link the physical mechanisms developing during deformation of magnesium (Mg) on the microscale with the macroscopic yielding properties of texture Mg samples. It will be shown that the mechanical behavior of hcp metals may be understood and reproduced with the help of a visco-plastic model for crystal plasticity and a phenomenological yield criterion with appropriate hardening behavior. The study of single crystal specimens subjected to channel die compression tests reveals the active slip systems and twinning systems of the material considered. The material anisotropy at mesoscale is reproduced by using adequate critical resolved shear stresses (CRSS) for the considered deformation mechanisms. In order to describe the macroscopic behavior, texture is incorporated into polycrystalline Representative Volume Elements (RVEs) and various mechanical properties of extruded bars and rolled plates can be predicted. For RVEs exhibiting the texture of rolled plates the numerical results reveal the plate's anisotropic yielding and hardening behavior on a mesoscale. In order to extend the modeling possibilities to process simulations and to allow for time-saving simulations of structural behavior, a phenomenological yield surface accounting for anisotropy and tension/compression asymmetry has been established and implemented in a finite element code. Its numerous model parameters are calibrated by an optimization

  16. The application of EBSP in the research of deformation microstructure of metals

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The basic principle and application of EBSP in the research of deformed microstructure are illustrated in this paper. The results suggest that EBSP can be applied in the research of deformation microstructure and crystallography of metals to substitute for TEM.

  17. Microstructure and strength of a deformation processed aluminum-20%tin metal-metal composite

    Science.gov (United States)

    Xu, Kai

    An Al-20vol.% Sn metal-metal composite was deformation processed by extrusion, swaging, and wire drawing to a total true strain of 7.4, resulting in a microstructure with Sn filaments in an Al matrix. Both the size and spacing of the Sn filaments decreased as deformation processing progressed. Immediately after deformation, the Sn second phase showed a convoluted, ribbon-shaped filamentary morphology, but the Sn filaments spheroidized during prolonged storage at room temperature. The driving force for spheroidization is chemical potential gradient due to curvature difference along Sn filaments. A critical wavelength of lambda crit = 2piR can be used to determine the spheroidization tendency of Sn cylinder. When lambda > 2piR, spheroidization is predicted to occur. The strength of these composites increased exponentially with the reduction in spacing of the Sn filaments. The relationship between UTS and deformation true strain is UTS = 72.6 exp(0.20eta). A Hall-Petch relationship between strength and filament spacing has been observed. Strengthening results from the filaments acting as barriers for dislocation motion. The primary shape instability modes are cylinderization of ribbons, boundary splitting, spheroidization of cylinders, and edge spheroidization of ribbons. The determining factors dictating which mechanism is active are grain boundary energy, interfacial energy, and ribbon cross section aspect ratio. The fiber texture was determined by orientation imaging microscopy to be for Al and for Sn. The 290 MPa ultimate tensile strength of the composite was greater than the rule-of-mixtures prediction. Comparisons are made with Al-Nb, Al-Ti and Al-Mg deformation processed metal metal composites and to various strengthening models for metal-metal composites.

  18. Plastic Deformation of Metal Tubes Subjected to Lateral Blast Loads

    Directory of Open Access Journals (Sweden)

    Kejian Song

    2014-01-01

    Full Text Available When subjected to the dynamic load, the behavior of the structures is complex and makes it difficult to describe the process of the deformation. In the paper, an analytical model is presented to analyze the plastic deformation of the steel circular tubes. The aim of the research is to calculate the deflection and the deformation angle of the tubes. A series of assumptions are made to achieve the objective. During the research, we build a mathematical model for simply supported thin-walled metal tubes with finite length. At a specified distance above the tube, a TNT charge explodes and generates a plastic shock wave. The wave can be seen as uniformly distributed over the upper semicircle of the cross-section. The simplified Tresca yield domain can be used to describe the plastic flow of the circular tube. The yield domain together with the plastic flow law and other assumptions can finally lead to the solving of the deflection. In the end, tubes with different dimensions subjected to blast wave induced by the TNT charge are observed in experiments. Comparison shows that the numerical results agree well with experiment observations.

  19. Development of a microwave-assisted digestion method using ICP-OES to measure metals in gum deposits of internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Allan N.S.; Costa, Rouse S.; Gouveia, Sandro T.; Lopes, Gisele S. [Departamento de Quimica Analitica e Fisico-Quimica, Universidade Federal do Ceara, Fortaleza, CE (Brazil)

    2010-11-15

    The heterogeneous nature of gum samples obtained from the deposits of internal combustion engines is the main difficulty in accurate determination of their metal content. A microwave-assisted digestion method was implemented using factorial experimental design. The optimization of this procedure was carried out by first evaluating the effects of variables on the response (i.e., the residual carbon content or RCC). The variables of maximum heating power, heating time and nitric acid volume were studied. The RCC response was measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The time of maximum heating power was essential to obtain a desired RCC. The surface response was constructed with optimal conditions presented at 6 min and heating power of 700 W. Amounts of aluminum (Al), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn) were determined in 26 gum samples by ICP-OES. Ca, Fe, Mg and Zn were found at mg g{sup -1} levels in the samples, while Al, Cu, Mn, Ni and Pb were found at mg kg{sup -1} levels. Principal component analysis (PCA) was used to establish a correlation between the gum samples and the different metal contents. Three distinct groups were separated according to the characteristics of the collected samples. (author)

  20. Nanocrystalline Metal Hydrides Obtained by Severe Plastic Deformations

    Directory of Open Access Journals (Sweden)

    Jacques Huot

    2012-01-01

    Full Text Available It has recently been shown that Severe Plastic Deformation (SPD techniques could be used to obtain nanostructured metal hydrides with enhanced hydrogen sorption properties. In this paper we review the different SPD techniques used on metal hydrides and present some specific cases of the effect of cold rolling on the hydrogen storage properties and crystal structure of various types of metal hydrides such as magnesium-based alloys and body centered cubic (BCC alloys. Results show that generally cold rolling is as effective as ball milling to enhance hydrogen sorption kinetics. However, for some alloys such as TiV0.9Mn1.1 alloy ball milling and cold rolling have detrimental effect on hydrogen capacity. The exact mechanism responsible for the change in hydrogenation properties may not be the same for ball milling and cold rolling. Nevertheless, particle size reduction and texture seems to play a leading role in the hydrogen sorption enhancement of cold rolled metal hydrides.

  1. Investigating Deformation and Failure Mechanisms in Nanoscale Multilayer Metallic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Zbib, Hussein M. [Washington State Univ., Pullman, WA (United States); Bahr, David F. [Purdue Univ., West Lafayette, IN (United States)

    2014-10-22

    Over the history of materials science there are many examples of materials discoveries that have made superlative materials; the strongest, lightest, or toughest material is almost always a goal when we invent new materials. However, often these have been a result of enormous trial and error approaches. A new methodology, one in which researchers design, from the atoms up, new ultra-strong materials for use in energy applications, is taking hold within the science and engineering community. This project focused on one particular new classification of materials; nanolaminate metallic composites. These materials, where two metallic materials are intimately bonded and layered over and over to form sheets or coatings, have been shown over the past decade to reach strengths over 10 times that of their constituents. However, they are not yet widely used in part because while extremely strong (they don’t permanently bend), they are also not particularly tough (they break relatively easily when notched). Our program took a coupled approach to investigating new materials systems within the laminate field. We used computational materials science to explore ways to institute new deformation mechanisms that occurred when a tri-layer, rather than the more common bi-layer system was created. Our predictions suggested that copper-nickel or copper-niobium composites (two very common bi-layer systems) with layer thicknesses on the order of 20 nm and then layered 100’s of times, would be less tough than a copper-nickel-niobium metallic composite of similar thicknesses. In particular, a particular mode of permanent deformation, cross-slip, could be activated only in the tri-layer system; the crystal structure of the other bi-layers would prohibit this particular mode of deformation. We then experimentally validated this predication using a wide range of tools. We utilized a DOE user facility, the Center for Integrated Nanotechnology (CINT), to fabricate, for the first time, these

  2. Low Temperature Heat Capacity of a Severely Deformed Metallic Glass

    Science.gov (United States)

    Bünz, Jonas; Brink, Tobias; Tsuchiya, Koichi; Meng, Fanqiang; Wilde, Gerhard; Albe, Karsten

    2014-04-01

    The low temperature heat capacity of amorphous materials reveals a low-frequency enhancement (boson peak) of the vibrational density of states, as compared with the Debye law. By measuring the low-temperature heat capacity of a Zr-based bulk metallic glass relative to a crystalline reference state, we show that the heat capacity of the glass is strongly enhanced after severe plastic deformation by high-pressure torsion, while subsequent thermal annealing at elevated temperatures leads to a significant reduction. The detailed analysis of corresponding molecular dynamics simulations of an amorphous Zr-Cu glass shows that the change in heat capacity is primarily due to enhanced low-frequency modes within the shear band region.

  3. Gum (Periodontal) Disease

    Science.gov (United States)

    ... gum disease are gingivitis and periodontitis. Gingivitis and Periodontitis In gingivitis, the gums become red, swollen and ... gingivitis is not treated, it can advance to periodontitis. In periodontitis, gums pull away from the teeth ...

  4. STATISTICAL MECHANICS MODELING OF MESOSCALE DEFORMATION IN METALS

    Energy Technology Data Exchange (ETDEWEB)

    Anter El-Azab

    2013-04-08

    The research under this project focused on a theoretical and computational modeling of dislocation dynamics of mesoscale deformation of metal single crystals. Specifically, the work aimed to implement a continuum statistical theory of dislocations to understand strain hardening and cell structure formation under monotonic loading. These aspects of crystal deformation are manifestations of the evolution of the underlying dislocation system under mechanical loading. The project had three research tasks: 1) Investigating the statistical characteristics of dislocation systems in deformed crystals. 2) Formulating kinetic equations of dislocations and coupling these kinetics equations and crystal mechanics. 3) Computational solution of coupled crystal mechanics and dislocation kinetics. Comparison of dislocation dynamics predictions with experimental results in the area of statistical properties of dislocations and their field was also a part of the proposed effort. In the first research task, the dislocation dynamics simulation method was used to investigate the spatial, orientation, velocity, and temporal statistics of dynamical dislocation systems, and on the use of the results from this investigation to complete the kinetic description of dislocations. The second task focused on completing the formulation of a kinetic theory of dislocations that respects the discrete nature of crystallographic slip and the physics of dislocation motion and dislocation interaction in the crystal. Part of this effort also targeted the theoretical basis for establishing the connection between discrete and continuum representation of dislocations and the analysis of discrete dislocation simulation results within the continuum framework. This part of the research enables the enrichment of the kinetic description with information representing the discrete dislocation systems behavior. The third task focused on the development of physics-inspired numerical methods of solution of the coupled

  5. Deformation behavior of laser bending of circular sheet metal

    Institute of Scientific and Technical Information of China (English)

    Q. Nadeem; S. J. Na

    2011-01-01

    @@ The application of a thermal source in non-contact forming of sheet metal has long been used.However, the replacement of this thermal source with a laser beam promises much greater controllability of the process.This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components.%The application of a thermal source in non-contact forming of sheet metal has long been used. However, the replacement of this thermal source with a laser beam promises much greater controllability of the process. This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components. Forming is made possible through laser-induced non-uniform thermal stresses. In this letter, we use the geometrical transition from rectangular to circle-shaped specimen and ring-shaped specimen to observe the effect of geometry on deformation in laser forming. We conduct a series of experiments on a wide range of specimen geometries. The reasons for this behavior are also analyzed. Experimental results are compared with simulated values using the software ABAQUS. The utilization of line energy is found to be higher in the case of laser forming along linear irradiation than along curved ones. We also analyze the effect of strain hindrance. The findings of the study may be useful for the inverse problem, which involves acquiring the process parameters for a known target shape of a wide range of complex shape geometries.

  6. XAFS Debye-Waller factors for deformed hemes and metal substituted hemes

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, N; Mion, T; Ramirez, C [Department of Physics and Geology, University of Texas-Pan American, Edinburg, TX 78539 (United States); Bunker, G, E-mail: dimakis@utpa.ed [Department of Biological Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States)

    2009-11-15

    We present an efficient and accurate method for calculating XAFS Debye-Waller factors for deformed active sites of hemoproteins and metal substituted hemes. Based on the Normal Coordinate Structural Decomposition scheme, the deformation of the porphyrin macrocycle is expressed as a linear combination of the normal modes of the planar species. In our approach, we identify the modes that contribute most to the deformation. Small metal-porphyrin structures which match the macrocycle structural deformation of the deformed hemoprotein site are used to calculate the Debye-Waller parameters at sample's temperature. The Debye-Waller factors are directly obtained by calculating the normal mode spectrum of the corresponding metal-porphyrin structure using Density Functional Theory. Our method is tested on Ni-tetraadamantyl porphyrin and cytochrome c structures with more than 500 available scattering paths.

  7. Increasing the accuracy during the production of curved metallic billets by bending deformation

    Science.gov (United States)

    Brovman, T. V.; Kutuzov, A. A.

    2016-05-01

    The elastoplastic deformation of a billet by bending is considered. The deformation forces are determined and formulas are derived to estimate the accuracy of the curvature of the billet. A bending technology is developed to increase the accuracy of a billet and to decrease the metal losses. The results obtained were used at Tver' Glass Company to produce curved billets.

  8. Structural Changes in Deformed Soft Magnetic Ni-Based Metallic Glass

    NARCIS (Netherlands)

    Jurikova, A.; Csach, K.; Miskuf, J.; Ocelik, V.

    2009-01-01

    The effects of intensive plastic deformation of the soft magnetic metallic glass Ni Si 13 on the structural relaxation were examined. The enthalpy changes studied by differential scanning calorimetry revealed that the intensive plastic deformation was associated with the partial structural relaxatio

  9. Structural Transformations in Metallic Materials During Plastic Deformation

    Science.gov (United States)

    Zasimchuk, E.; Turchak, T.; Baskova, A.; Chausov, N.; Hutsaylyuk, V.

    2017-03-01

    In this paper, the structure formation during the plastic deformation of polycrystalline nickel and aluminum based alloy 2024-T3 is investigated. The possibility of the relaxation and synergetic structure formation is examined. It is shown the deformation softening to be due to the crystallization of the amorphous structure of hydrodynamics flow channels (synergetic structure) HC as micrograins and their subsequent growth. The possible mechanism of micrograins' growth is proposed. The deformation processes change the phase composition of the multiphase alloy 2024-T3. It is shown by the quantitative analysis of the structures which were deformed in different regimes of the alloy samples. A method for increasing of the fatigue life through a dynamic pre-deformation is suggested.

  10. Structural Transformations in Metallic Materials During Plastic Deformation

    Science.gov (United States)

    Zasimchuk, E.; Turchak, T.; Baskova, A.; Chausov, N.; Hutsaylyuk, V.

    2017-02-01

    In this paper, the structure formation during the plastic deformation of polycrystalline nickel and aluminum based alloy 2024-T3 is investigated. The possibility of the relaxation and synergetic structure formation is examined. It is shown the deformation softening to be due to the crystallization of the amorphous structure of hydrodynamics flow channels (synergetic structure) HC as micrograins and their subsequent growth. The possible mechanism of micrograins' growth is proposed. The deformation processes change the phase composition of the multiphase alloy 2024-T3. It is shown by the quantitative analysis of the structures which were deformed in different regimes of the alloy samples. A method for increasing of the fatigue life through a dynamic pre-deformation is suggested.

  11. Deformation and failure mechanisms in metal matrix composites

    Science.gov (United States)

    Newaz, G.; Majumdar, B. S.

    1991-01-01

    An investigation was undertaken to determine the key deformation mechanisms and their interaction leading to failure of both 0 degree and 90 degree Ti 15-3/SCS-6 laminae under monotonic loading. The experimental results suggest that inelastic deformation in the 0-degree lamina is dominated by plastic deformation and that in the 90-degree lamina is dominated by both fiber-matrix debonding and plasticity. The loading-unloading response, monitoring of Poisson's ratio and microscopy were utilized to identify the key deformation mechanisms. The sequence of deformation mechanisms leading to failure are identified for both the 0 and the 90-degree specimens. The threshold strains for plasticity or damage which are referred to as 'microdeformation' in the 0 deg and 90 deg laminae are approximately 0.004 and 0.002, respectively, at room temperature. These strain levels may be considered critical in initiation based structural design with these composites.

  12. Conformal mapping modeling of metal plastic deformation and die cavity in special-shaped extrusion

    Institute of Scientific and Technical Information of China (English)

    齐红元; 朱衡君; 杜凤山; 刘才

    2002-01-01

    With the help of Complex Function Mapping studied results, the analysis function of Conformal Mapping is set up. Since the complicated three dimension's deformation problems are transferred into two dimension problems, both the stream function and strain ratio field are analyzed in the metal plastic deformation. Using the upper-bound principles, the theory of metal deformation and die cavity optimized modeling is established for random special-shaped product extrusion. As a result, this enables the realization of intelligent technique target in the die cavity of CAD/CAM integration.

  13. Ra and the average effective strain of surface asperities deformed in metal-working processes

    DEFF Research Database (Denmark)

    Bay, Niels; Wanheim, Tarras; Petersen, A. S

    1975-01-01

    Based upon a slip-line analysis of the plastic deformation of surface asperities, a theory is developed determining the Ra-value (c.l.a.) and the average effective strain in the surface layer when deforming asperities in metal-working processes. The ratio between Ra and Ra0, the Ra-value after...... and before deformation, is a function of the nominal normal pressure and the initial slope γ0 of the surface asperities. The last parameter does not influence Ra significantly. The average effective strain View the MathML sourcege in the deformed surface layer is a function of the nominal normal pressure...

  14. In situ observation of deformation processes in nanocrystalline face-centered cubic metals.

    Science.gov (United States)

    Kobler, Aaron; Brandl, Christian; Hahn, Horst; Kübel, Christian

    2016-01-01

    The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline Pd x Au1- x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin-twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains.

  15. Rapid Finite Element Analysis of Bulk Metal Forming Process Based on Deformation Theory

    Institute of Scientific and Technical Information of China (English)

    WANG Peng; DONG Xiang-huai; FU Li-jun

    2009-01-01

    The one-step finite element method (FEM), based on plastic deformation theory, has been widely used to simulate sheet metal forming processes, but its application in bulk metal forming simulation has been seldom investigated, because of the complexity involved. Thus, a bulk metal forming process was analyzed using a rapid FEM based on deformation theory. The material was assumed to be rigid-plastic and strain-hardened. The constitutive relationship between stress and total strain was adopted, whereas the incompressible condition was enforced by penalty function. The geometrical non-linearity in large plastic deformation was taken into consideration. Furthermore, the force boundary condition was treated by a simplified equivalent approach, considering the contact history. Based on constraint variational principle, the deformation FEM was proposed. The one-step forward simulation of axisymmetric upsetting process was performed using this method. The results were compared with those obtained by the traditional incremental FEM to verify the feasibility of the proposed method.

  16. Deformation behavior during nanoindentation in Ce-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingchen; XING Dongmei; ZHANG Taihua; WEI Bingchen; LI Weihuo; WANG Yuren

    2006-01-01

    The deformation behavior and the effect of the loading rate on the plastic deformation in Ce-based bulk metallic glasses (BMGs) were investigated through nanoindentation tests. The results showed that the loading rate dependence of plastic deformation during nanoindentation measurements in the Ce-based BMGs is quite unique in contrast to that of other BMG alloys. The load-displacement (P-h)curves of Ce60Al15Cu10Ni15 BMG exhibit a homogeneous plastic deformation at low loading rates, and a prominent serrated flow at high strain rates, whereas,the P-h curves of Ce65Al10Cu10Ni10Nb5 exhibit homogenous plastic deformation at all studied loading rates. The room temperature creep behavior could clearly be observed in these two alloys. The mechanism of the unique plastic deformation feature in the Ce-based BMGs was studied.

  17. Recovery by triple junction motion in heavily deformed metals

    DEFF Research Database (Denmark)

    Yu, Tianbo; Hansen, Niels; Huang, Xiaoxu

    2015-01-01

    A number of processes may occur during recovery, which reduce the stored energy and coarsen the structure, paving the way for the nucleation of recrystallization. In this review, recovery is discussed based on the initial deformed structure. Recovery in samples deformed to low-to-medium strains...... is briefly considered, whereas recovery in samples deformed to much higher strains is discussed in more detail. An example is Al, where a new and important recovery mechanism is triple junction motion, which can remove thin lamellae and consequently increase the thickness of neighbouring lamellae....... This recovery mechanism therefore coarsens the structure and causes a gradual transition from a lamellar to a near equiaxed structure preceding recrystallization. This mechanism is discussed in conjunction with structural pinning, which stabilizes the coarsening microstructure, thereby balancing the forces...

  18. Nucleation of recrystallization at selected sites in deformed fcc metals

    DEFF Research Database (Denmark)

    Xu, Chaoling

    likely is nucleation. In the weakly rolled and indented aluminum samples, it is found that hardness indentations lead to large orientation rotations near indentation tips. In initial grains of different crystallographic orientations, the grains with higher stored energy (SE) in the rolled microstructures...... mechanisms. In the cold rolled nickel samples, the preference of triple junctions (TJs) and grain boundaries (GBs) as nucleation sites is observed. The majorities of the nuclei have the same orientations as the surrounding matrix or are twin-related to a surrounding deformed grain. Only a few nuclei...... within the embryonic volumes in the deformed state. It is further suggested that boundaries between nuclei and the deformed matrix of less than 5° hinder subsequent growth of the nuclei. For all the observed cases, it is suggested that the nucleation mechanism may be strain induced boundary migration...

  19. Cross-linked natural gum resins, when inserted in shampooing product, result infallible to eliminate several metallic ions risky for hair keratin

    Directory of Open Access Journals (Sweden)

    Martini Lorenzo

    2016-04-01

    Full Text Available Aims of my research is to herald the method of eliminating Calcium and Magnesium ions that remain onto hair and scalp keratin after washing with common hard water and trivial shampooing products, but even of removing other metals as Lead, Silicon and Nickel ions which can be retrieved in manifold building materials like mortar, cement, concrete, pozzolans, limestone and asbest, most of workers throughout the world are directly involved with, because of their continuous contact with those chemical materials. I have selected twelve volunteers (workers who are directly in contact with building materials containing Calcium and Magnesium ions and prayed them to use three types of shampooing products of my invention (containing special gum resins previously cross-linked in order to uptake or sorption the metallic ions after having used, in precedence, trivial shampoos (bought at the same store and used the same tap water, since they live all in the same town. I calculated the difference of quantities of Magnesium and Calcium that remain onto hair and scalp keratin, using a general and trivial shampoo respect to my products, apt to remove the same metallic ions. Results are satisfactory and encouraging.

  20. Analysis on volume invariability of metal circular shaft in torsion deformation

    Science.gov (United States)

    Yang, Li-Hong; Zou, Guang-Ping; He, Yun-Zeng; Wang, Hui

    2010-03-01

    Volume invariability of metal circular shaft in the case of small strain torsion deformation and large strain torsion deformation was, respectively, discussed experimentally and theoretically in this study. In accordance with the elastoplastic theory, it was given that the shear stress did not cause the change of volume in the large strain range. By utilizing torsion experiment with the solid shaft of low carbon steel, it was proved that metal can meet the conditions of the volume invariability in torsion deformation while the cumulative damage was not very serious. Volumetric deformation was analyzed in torsion of circular shaft in the perspective of micromechanics. Finally, Swift effect of solid circular shaft and tubular shaft of brass material were interpreted by using the formulae of elastoplastic critic load obtained from double-limb bar model test presented by Shanley.

  1. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  2. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore,it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work,the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow,the typical plastic deformation feature of BMGs,could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition,the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  3. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    LI Lei; LIU Yuan; ZHANG TaiHua; GU JianSheng; WEI BingChen

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore, it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work, the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow, the typical plastic deformation feature of BMGs, could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition, the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  4. Phenomenon of transformed adiabatic shear band surrounded by deformed adiabatic shear band of ductile metal

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-bin

    2008-01-01

    The coexistent phenomenon of deformed and transformed adiabatic shear bands(ASBs) of ductile metal was analyzed using the JOHNSON-COOK model and gradient-dependent plasticity(GDP). The effects of melting point, density, heat capacity and work to heat conversion factor were investigated. Higher work to heat conversion factor, lower density, lower heat capacity and higher melting point lead to wider transformed ASB and higher local plastic shear deformation between deformed and transformed ASBs. Higher work to heat conversion factor, lower density, lower heat capacity and lower melting point cause higher local plastic shear deformation in the deformed ASB. Three reasons for the scatter in experimental data on the ASB width were pointed out and the advantages of the work were discussed. If the transformed ASB width is used to back-calculate the internal length parameter in the GDP, undoubtedly, the parameter will be extremely underestimated.

  5. ANALYTICAL MODEL OF CERAMIC/METAL ARMOR IMPACTED BY DEFORMABLE PROJECTILE

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new analytical model was established to describe the complex behavior of ceramic/metal armor under impact of deformable projectile by assuming some hypotheses.Three aspects were taken into account: the mushrooming deformation of the projectile,the fragment of ceramic tile and the formation and change of ceramic conoid and the deformation of the metal backup plate. Solving the set of equations, all the variables were obtained for the different impact velocities: the extent and particle velocity in rigid zone; the extent, cross-section area and particle velocity in plastic zone; the velocity and depth of penetration of projectile to the target; the reduction in volume and compressive strength of the fractured ceramic conoid; the displacement and movement velocity of the effective zone of backup plate. Agreement observed among analytical result, numerical simulation and experimental result confirms the validity of the model, suggesting the model developed can be a useful tool for ceramic/metal armor design.

  6. Estimation of stored energy in deformed metals from EBSD sets

    Institute of Scientific and Technical Information of China (English)

    YU Tianbo; Andrew GODFREY

    2008-01-01

    A number of methods for estimating the stored energy of deformation from EBSD data have been examined.The methods are illustrated here using samples of AA1100 deformed to strains of εvM=2.4 and εvM=4.0 using the accumulative roll bonding process.A qualitative method,based on pattern contrast,reveals some aspects of local differences in stored energy in the deformed samples.Quantitative methods where the stored energy is estimated through the use of the Read-Shockley equation have also been examined.A special mean misorientation angle is developed to take account of nonlinearity of the Read-Shockley equation.Two approaches have been considered.One is based on subgrain reconstruction and the other is based on misorientation angles taken directly from an orientation map.Calculations show that the subgrain method is particularly sensitive to orientation noise in the data and care must be taken when using this method.

  7. The role of deformation microstructure in recovery and recrystallization of heavily strained metals

    DEFF Research Database (Denmark)

    Hansen, Niels

    2012-01-01

    Metals deformed to high and ultrahigh strains are characterized by a nanoscale microstructure, a large fraction of high angle boundaries and a high dislocation density. Another characteristic of such a microstructure is a large stored energy that combines elastic energy due to dislocations...... and boundary energy. Parameters of the deformed microstructure significantly affect annealing processes such as recovery and recrystallization. For example, the recovery rate can be significantly increased after high strain deformation and restoration may occur as either discontinuous recrystallization...... of recovery on subsequent restoration processes is discussed along with the effect of heterogeneities both on the local scale and on the sample scale. © (2012) Trans Tech Publications, Switzerland....

  8. Deformation-induced martensitic transformation in Cu-Zr-Al(Ti) bulk metallic glass composites

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ram Bachchan; Pauly, Simon; Das, Jayanta; Eckert, Juergen [Institut fuer Komplexe Materialien, IFW Dresden (Germany)

    2009-07-01

    Plastic deformation of Cu-Zr-(Al, Ti) bulk metallic glass (BMG) composites induces a martensitic phase transformation from the B2 to the B19* CuZr phase. Addition of Ti to binary Cu-Zr increases the temperature above which the B2 CuZr phase becomes stable. This affects the phase formation upon quenching in Cu-Zr-Ti BMG composites. The deformation-induced martensitic transformation is believed to cause the strong work hardening and to contribute to the large compressive deformability with plastic strains up to 15%.

  9. DEFORMATION ANALYSIS OF SHEET METAL SINGLE-POINT INCREMENTAL FORMING BY FINITE ELEMENT METHOD SIMULATION

    Institute of Scientific and Technical Information of China (English)

    MA Linwei; MO Jianhua

    2008-01-01

    Single-point incremental forming (SPIF) is an innovational sheet metal forming method without dedicated dies, which belongs to rapid prototyping technology. In generalizing the SPIF of sheet metal, the deformation analysis on forming process becomes an important and useful method for the planning of shell products, the choice of material, the design of the forming process and the planning of the forming tool. Using solid brick elements, the finite element method(FEM) model of truncated pyramid was established. Based on the theory of anisotropy and assumed strain formulation, the SPIF processes with different parameters were simulated. The resulted comparison between the simulations and the experiments shows that the FEM model is feasible and effective. Then, according to the simulated forming process, the deformation pattern of SPIF can be summarized as the combination of plane-stretching deformation and bending deformation. And the study about the process parameters' impact on deformation shows that the process parameter of interlayer spacing is a dominant factor on the deformation. Decreasing interlayer spacing, the strain of one step decreases and the formability of blank will be improved. With bigger interlayer spacing, the plastic deformation zone increases and the forming force will be bigger.

  10. Dynamic Plastic Deformation (DPD): A Novel Technique for Synthesizing Bulk Nanostructured Metals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    While some superior properties of nanostructured materials (with structural scales below 100 nm) have attracted numerous interests of material scientists, technique development for synthesizing nanostructured metals and alloys in 3-dimensional (3D) bulk forms is still challenging despite of extensive investigations over decades.Here we report a novel synthesis technique for bulk nanostructured metals based on plastic deformation at high Zener-Hollomon parameters (high strain rates or low temperatures), i.e., dynamic plastic deformation (DPD).The basic concept behind this approach will be addressed together with a few examples to demonstrate the capability and characteristics of this method. Perspectives and future developments of this technique will be highlighted.

  11. Observations on the deformation-induced beta internal friction peak in bcc metals

    Science.gov (United States)

    Dicarlo, J. A.

    1974-01-01

    During a study of the effects of electron irradiation on the tungsten alpha mechanism, internal friction data were obtained. The data indicate that the mechanism underlying the beta peak does not possess the relaxation parameters generally associated with a simple dislocation process. The significance of the experimental results in the light of beta observations in other metals is discussed. It is suggested that the beta peaks in deformed bcc metals are the anelastic result of the thermally-activated relaxation of deformation-induced imperfections.

  12. Synergy effects in the deformation response of thermodynamically open metal-hydrogen systems

    Energy Technology Data Exchange (ETDEWEB)

    Spivak, L V [Perm State University, Perm (Russian Federation)

    2008-09-30

    This paper reviews how polycrystalline and amorphous metals respond to the combined effect of a nonuniform force field and a high-intensity hydrogen (deuterium) diffusion flow. It is shown that deformation effects in such thermodynamically open systems result from phase transitions occurring due to changes in the hydrogen (deuterium) concentration. The necessary and sufficient criteria for observing such synergy effects are formulated. It is shown that the deformation response in a nonuniform stress field is a very sensitive means for indicating first and second-order structural phase transitions in metal-hydrogen systems. (reviews of topical problems)

  13. Metal ion-induced alginate-locust bean gum IPN microspheres for sustained oral delivery of aceclofenac.

    Science.gov (United States)

    Jana, Sougata; Gandhi, Arijit; Sheet, Subrata; Sen, Kalyan Kumar

    2015-01-01

    The alginate microspheres represent a useful tool for sustained oral delivery of drugs but exhibit several problems associated with the stability and rapid release of drugs at higher pH values. To overcome these drawbacks, alginate-locust bean gum (LBG) interpenetrating microspheres were prepared by calcium ion (Ca(+2)) induced ionotropic gelation technique for prolonged release of aceclofenac. The drug entrapment efficiency of these microspheres was found to be 59-93%. The microspheres lied in the size range of 406-684μm. Scanning electron microscopy revealed spherical shape of the microspheres. No drug-polymer interaction was evident after infrared spectroscopy analysis. The microspheres provided sustained release of aceclofenac in phosphate buffer solution (pH 6.8) over a period of 8h. The drug release data were fitted into the Korsmeyer-Peppas model and the drug release was found to follow anomalous (non-Fickian) diffusion mechanism. Pharmacodynamic study of the microspheres showed a prolonged anti-inflammatory activity in carrageenan-induced rat paw model following oral administration.

  14. Slip systems, dislocation boundaries and lattice rotations in deformed metals

    DEFF Research Database (Denmark)

    Winther, Grethe

    2009-01-01

    strains at room temperature are analysed. A major result is that, by contrast to previous beliefs, the boundaries align with specific crystallographic planes, which depend on the crystallographic grain orientation. This grain orientation dependence originates from an underlying dependence of the active...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

  15. Deformation of Semi-Solid Metals - Refining, Strengthening, and Rheological Behavior.

    Science.gov (United States)

    1982-07-15

    described. This work extends earlier studies on " Rheocasting " and has broad, practical implications. The original Rheocast work, sponsored by ARO, led to... Rheocasting has now finally become a commercial reality. The broad area of forming and otherwise processing of metals in the semi-solid state is one that...than Rheocasting , for forming metals in their semi-solid state. And we wondered as well if we might find some way, through deformation in the semi-solid

  16. Modeling complex plastic deformation and fracture of metals under disproportionate loading

    Science.gov (United States)

    Volkov, I. A.; Korotkikh, Yu. G.; Tarasov, I. S.

    2009-09-01

    A mathematical model is developed to describe fatigue-damage accumulation in structural materials (metals and their alloys) on multiaxial paths of disproportionate combined heat and power loading. The effect of the shape of the strain path on the fatigue life of metals was studied to obtain qualitative and quantitative estimates of the obtained constitutive relations. It is shown that the proposed constitutive relations adequately describe the main elastoplastic deformation effects and damage accumulation in structural materials for arbitrary strain paths.

  17. The Identification of the Deformation Stage of a Metal Specimen Based on Acoustic Emission Data Analysis.

    Science.gov (United States)

    Zou, Shenao; Yan, Fengying; Yang, Guoan; Sun, Wei

    2017-04-07

    The acoustic emission (AE) signals of metal materials have been widely used to identify the deformation stage of a pressure vessel. In this work, Q235 steel samples with different propagation distances and geometrical structures are stretched to get the corresponding acoustic emission signals. Then the obtained acoustic emission signals are de-noised by empirical mode decomposition (EMD), and then decomposed into two different frequency ranges, i.e., one mainly corresponding to metal deformation and the other mainly corresponding to friction signals. The ratio of signal energy between two frequency ranges is defined as a new acoustic emission characteristic parameter. Differences can be observed at different deformation stages in both magnitude and data distribution range. Compared with other acoustic emission parameters, the proposed parameter is valid in different setups of the propagation medium and the coupled stiffness.

  18. Analysis and experiment on deformation of sheet metal by laser shock wave

    Institute of Scientific and Technical Information of China (English)

    YANG Chao-jun; ZHANG Yong-kang; ZHOU Jian-zhong; NI Ming-xiong; DU Jian-jun; HUANG Shu; FENG Ai-xin; ZHANG Lei-hong

    2006-01-01

    The mechanism of laser shock deformation and the reason for the production of the shockwave are introduced.An evaluation formula of the detonation wave pressure in the system of laser,energy transferring-medium and sheet metal is built according to the theory of detonation wave and blasting gas-dynamics.The minimal energy of the laser pulse is evaluated on the basis of the formula of the laser shock pressure and evaluation of dynamic yielding strength.The experiment is also validated.The result shows that the quantity of sheet metal deforming is nonlinearly increased with laser energy,i.e.,pressure of the laser shock wave.Under a laser-induced ultra-high pressure and high strain rate,structural steels and composite materials undergo plastic deformation.

  19. Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics

    NARCIS (Netherlands)

    Huang, M.; Rivera-Diaz-del-Castillo, P.E.J.; Bouaziz, O.; Van der Zwaag, S.

    2009-01-01

    Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that t

  20. DIRECT SPECTRUM ANALYSIS OF ANELASTIC DEFORMATION RESPONSE DURING STRUCTURAL RELAXATION OF AMORPHOUS METALS

    NARCIS (Netherlands)

    CSACH, K; Ocelik, Vaclav; MISKUF, J; BENGUS, VZ; DUHAJ, P

    1994-01-01

    Direct relaxation time spectrum analysis method has been successfully used to observe and. to study changes in the kinetics of isothermal anelastic deformation response of soft magnetic metallic glass Fe40Ni40B20 during structural relaxation. Computed relaxation time spectra contain three or four qu

  1. A Fully-Coupled Approach for Modelling Plastic Deformation and Liquid Lubrication in Metal Forming

    DEFF Research Database (Denmark)

    Üstünyagiz, Esmeray; Christiansen, Peter; Nielsen, Chris V.;

    2016-01-01

    This paper presents a new approach for combined modelling of plastic deformation andliquid lubrication in the contact interfaces between material and tooling in metal forming includingsituations where the lubricant is functioning as a pressure carrier. The approach is an alternative toconventiona...... and numerical fundamentals of the proposedapproach and includes selected examples in order to illustrate its advantages and limitations....

  2. Tailoring dislocation structures and mechanical properties of nanostructured metals produced by plastic deformation

    DEFF Research Database (Denmark)

    Huang, Xiaoxu

    2009-01-01

    The presence of a dislocation structure associated with low-angle dislocation boundaries and interior dislocations is a common and characteristic feature in nanostructured metals produced by plastic deformation, and plays an important role in determining both the strength and ductility of the nan...

  3. Compressive Deformation Induced Nanocrystallization of a Supercooled Zr-Based Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-Lin; SHAN De-Bin; MA Ming-Zhen; GUO Bin

    2008-01-01

    The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high ternperatures.

  4. Dislocation nucleation and vacancy formation during high-speed deformation of fcc metals

    DEFF Research Database (Denmark)

    Schiøtz, J.; Leffers, T.; Singh, B.N.

    2001-01-01

    dislocation densities in the foils after deformation. This was interpreted as evidence for a new dislocation-free deformation mechanism, resulting in a very high vacancy production rate. In this paper we investigate this proposition using large-scale computer simulations of bulk and thin films of copper......Recently, a dislocation-free deformation mechanism was proposed by Kiritani et al. on the basis of a series of experiments where thin foils of fee metals were deformed at very high strain rates. In the experimental study, they observed a large density of stacking fault tetrahedra but very low....... The dislocations are nucleated as single Shockley partials. The large stresses required before dislocations are nucleated result in a very high dislocation density, and therefore in many inelastic interactions between the dislocations. These interactions create vacancies and a very large vacancy concentration...

  5. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    OpenAIRE

    2014-01-01

    Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstruct...

  6. Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium

    Directory of Open Access Journals (Sweden)

    Lembit KOMMEL

    2012-12-01

    Full Text Available The mechanical and physical properties relationship from atomic level strain/stress causes dislocation density and electrical conductivity relationship, as well as crystallites deformation and hkl-parameter change in the severely deformed pure refractory rare metal Nb at ambient temperature and during short processing times. The above mentioned issues are discussed in this study. For ultrafine-grained and nanocrystalline microstructure forming in metal the equal-channel angular pressing and hard cyclic viscoplastic deformation were used. The flat deformation and heat treatment at different parameters were conducted as follows. The focused ion beam method was used for micrometric measures samples manufacturied under nanocrystalline microstructure study by transmission electron microscope. The microstructure features of metal were studied under different orientations by X-ray diffraction scattering method, and according to the atomic level strains, dislocation density, hkl-parameters and crystallite sizes were calculated by different computation methods. According to results the evolutions of atomic level strains/stresses, induced by processing features have great influence on the microstructure and advanced properties forming in pure Nb. Due to cumulative strain increase the tensile stress and hardness were increased significantly. In this case the dislocation density of Nb varies from 5.0E+10 cm–2 to 2.0E+11 cm–2. The samples from Nb at maximal atomic level strain in the (110 and (211 directions have the maximal values of hkl-parameters, highest tensile strength and hardness but minimal electrical conductivity. The crystallite size was minimal and relative atomic level strain maximal in (211 orientation of crystal. Next, flat deformation and heat treatment increase the atomic level parameters of severely deformed metal.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3091

  7. Microstructure, Properties and Atomic Level Strain in Severely Deformed Rare Metal Niobium

    Directory of Open Access Journals (Sweden)

    Lembit KOMMEL

    2012-12-01

    Full Text Available The mechanical and physical properties relationship from atomic level strain/stress causes dislocation density and electrical conductivity relationship, as well as crystallites deformation and hkl-parameter change in the severely deformed pure refractory rare metal Nb at ambient temperature and during short processing times. The above mentioned issues are discussed in this study. For ultrafine-grained and nanocrystalline microstructure forming in metal the equal-channel angular pressing and hard cyclic viscoplastic deformation were used. The flat deformation and heat treatment at different parameters were conducted as follows. The focused ion beam method was used for micrometric measures samples manufacturied under nanocrystalline microstructure study by transmission electron microscope. The microstructure features of metal were studied under different orientations by X-ray diffraction scattering method, and according to the atomic level strains, dislocation density, hkl-parameters and crystallite sizes were calculated by different computation methods. According to results the evolutions of atomic level strains/stresses, induced by processing features have great influence on the microstructure and advanced properties forming in pure Nb. Due to cumulative strain increase the tensile stress and hardness were increased significantly. In this case the dislocation density of Nb varies from 5.0E+10 cm–2 to 2.0E+11 cm–2. The samples from Nb at maximal atomic level strain in the (110 and (211 directions have the maximal values of hkl-parameters, highest tensile strength and hardness but minimal electrical conductivity. The crystallite size was minimal and relative atomic level strain maximal in (211 orientation of crystal. Next, flat deformation and heat treatment increase the atomic level parameters of severely deformed metal.DOI: http://dx.doi.org/10.5755/j01.ms.18.4.3091

  8. Thermal Recovery of Plastic Deformation in Dissimilar Metal Weld

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Dongxiao [Tsinghua Univ., Beijing (China); Yu, Xinghua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhang, Wei [The Ohio State Univ., Columbus, OH (United States); Crooker, Paul [Electric Power Research Inst. (EPRI), Palo Alto, CA (United States); David, Stan A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-05-23

    Stainless steel has been widely used in challenging environments typical to nuclear power plant structures, due its excellent corrosion resistance. Nickel filler metals containing high chromium concentration, including Alloy 82/182, are used for joining stainless steel to carbon steel components to achieve similar high resistance to stress corrosion cracking. However, the joint usually experience weld metal stress corrosion cracking (SCC), which affects the safety and structural integrity of light water nuclear reactor systems. A primary driving force for SCC is the high tensile residual stress in these welds. Due to large dimension of pressure vessel and limitations in the field, non-destructive residual stress measurement is difficult. As a result, finite element modeling has been the de facto method to evaluate the weld residual stresses. Recent studies on this subject from researchers worldwide report different residual stress value in the weldments [5]. The discrepancy is due to the fact that most of investigations ignore or underestimate the thermal recovery in the heat-affect zone or reheated region in the weld. In this paper, the effect of heat treatment on thermal recovery and microhardness is investigated for materials used in dissimilar metal joint. It is found that high equivalent plastic strains are predominately accumulated in the buttering layer, the root pass, and the heat affected zone, which experience multiple welding thermal cycles. The final cap passes, experiencing only one or two welding thermal cycles, exhibit less plastic strain accumulation. Moreover, the experimental residual plastic strains are compared with those predicted using an existing weld thermo-mechanical model with two different strain hardening rules. The importance of considering the dynamic strain hardening recovery due to high temperature exposure in welding is discussed for the accurate simulation of weld residual stresses and plastic strains. In conclsuion, the

  9. The Correlation of Stir Zone Texture Development with Base Metal Texture and Tool-Induced Deformation in Friction Stir Processing of Severely Deformed Aluminum

    Science.gov (United States)

    Sarkari Khorrami, M.; Kazeminezhad, Mohsen; Miyashita, Y.; Kokabi, A. H.

    2017-01-01

    The texture development during friction stir processing (FSP) of 1050 aluminum severely deformed at the strain magnitude of 2.32 was comprehensively discussed. It was observed that the component bar{B} of the ideal shear texture along with the cube texture was developed in the severely deformed base metal. The effects of base metal texture on the texture development of stir zone, thermo-mechanically affected zone, and heat-affected zone during FSP were examined. Also, the developed texture components in the vicinity of the FSP tool and the stir zone were correlated to the deformation induced by the rotating tool which consisted of pin and shoulder. The observed texture components in the longitudinal section of the stir zone were found coincided with the ideal shear ones, but different from those observed in the severely deformed base metal. It could be responsible for the fact that the material beneath the FSP tool is predominantly deformed and stirred by the shoulder rather than the pin. The independency of texture development in the stir zone from pin-induced deformation was also consistent with the observation associated with the stir zone geometry which was independent of the pin geometry. Microstructural evolutions in the regions located ahead of the FSP tool manifested the incident of static recovery and recrystallization as a result of the stored strain in the severely deformed base metal. These led to the development of almost random texture and the deterioration of base metal texture in this region. This suggested the independency of texture development in the stir zone from the texture of severely deformed base metal.

  10. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Jacek PAWLICKI

    2014-06-01

    Full Text Available Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstructural examinations and identification of the fracture type enabled to describe a correlation between strain rate, strain and microstructure.

  11. A Fully-Coupled Approach for Modelling Plastic Deformation and Liquid Lubrication in Metal Forming

    DEFF Research Database (Denmark)

    Üstünyagiz, Esmeray; Christiansen, Peter; Nielsen, Chris Valentin

    2016-01-01

    This paper presents a new approach for combined modelling of plastic deformation andliquid lubrication in the contact interfaces between material and tooling in metal forming includingsituations where the lubricant is functioning as a pressure carrier. The approach is an alternative toconventional...... elements with fictitious small stiffness to physical modelling based on a fullycoupled procedure in which the lubricant flow and the plastic deformation of the metallic materialare solved simultaneously. The approach takes advantage of the intrinsic velocity-pressurecharacteristics of the finite element...... flow formulation which stands on the border line between fluidand solid mechanics and allows treating the lubricants as viscous incompressible (or nearlyincompressible) fluid and the metallic materials as non-Newtonian, high viscous, incompressiblefluids. The presentation is focused on the theoretical...

  12. Compression deformation behaviors of sheet metals at various clearances and side forces

    Directory of Open Access Journals (Sweden)

    Zhan Mei

    2015-01-01

    Full Text Available Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. In this study, a finite element (FE model was established for the compression process of sheet specimens, to probe the deformation behavior. The results show that: With the decrease of the clearance from a very large value to a very small value, four defects modes, including plastic t-buckling, micro-bending, w-buckling, and in-plane compression deformation will occur. With the increase of the side force from a very small value to a very large value, plastic t-buckling, w-buckling, uniform deformation, and in-plane compression will occur. The difference in deformation behaviors under these two parameters indicates that the successful compression process without failures for sheet specimens only can be carried out under a reasonable side force.

  13. Mechanical deformation of atomic-scale metallic contacts: Structure and mechanisms

    DEFF Research Database (Denmark)

    Sørensen, Mads Reinholdt; Brandbyge, Mads; Jacobsen, Karsten Wedel

    1998-01-01

    We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated ele...... that the results measured in a nanocontact experiment depend significantly on the elastic stiffness of the experimental apparatus. For a soft setup, some of the atomic rearrangements might not be detected, whereas others are amplified.......We have simulated the mechanical deformation of atomic-scale metallic contacts under tensile strain using molecular dynamics and effective medium theory potentials. The evolution of the structure of the contacts and the underlying deformation mechanisms are described along with the calculated...... electronic conductance. Various defects such as intersecting stacking faults, local disorder, and vacancies are created during the deformation. Disordered regions act as weak spots that reduce the strength of the contacts. The disorder tends to anneal out again during the subsequent atomic rearrangements...

  14. Effect of deformation temperature on the hot compressive behavior of metal matrix composites with misaligned whiskers

    Institute of Scientific and Technical Information of China (English)

    LI Aibin; MENG Qingyuan; GENG Lin; DENG Chunfeng; YAN Yiwu

    2007-01-01

    A multi-inclusion cell model is used to investigate the effect of deformation temperature and whisker rotation on the hot compressive behavior of metal matrix composites with misaligned whiskers. Numerical results show that deformation temperature influences the work-hardening behavior of the matrix and the rotation behavior of the whiskers. With increasing temperature, the work hardening rate of the matrix decreases, but the whisker rotation angle increases. Both whisker rotation and the increase of deformation temperature can induce reductions in the load supported by whisker and the load transferred from matrix to whisker. Additionally, it is found that during large strain deformation at higher temperatures, the enhancing of deformation temperature can reduce the effect of whisker rotation. Meanwhile, the stress-strain behavior of the composite is rather sensitive to deformation temperature. At a relatively lower temperature (150℃), the composite exhibits work hardening due to the matrix work hardening, but at relatively higher temperatures (300℃ and above),the composite shows strain softening due to whisker rotation. It is also found that during hot compression at higher temperatures, the softening rate of the composite decreases with increasing temperature. The predicted stress-strain behavior of the composite is approximately in agreement with the experimental results.

  15. An exploration of plastic deformation dependence of cell viability and adhesion in metallic implant materials.

    Science.gov (United States)

    Uzer, B; Toker, S M; Cingoz, A; Bagci-Onder, T; Gerstein, G; Maier, H J; Canadinc, D

    2016-07-01

    The relationship between cell viability and adhesion behavior, and micro-deformation mechanisms was investigated on austenitic 316L stainless steel samples, which were subjected to different amounts of plastic strains (5%, 15%, 25%, 35% and 60%) to promote a variety in the slip and twin activities in the microstructure. Confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) revealed that cells most favored the samples with the largest plastic deformation, such that they spread more and formed significant filopodial extensions. Specifically, brain tumor cells seeded on the 35% deformed samples exhibited the best adhesion performance, where a significant slip activity was prevalent, accompanied by considerable slip-twin interactions. Furthermore, maximum viability was exhibited by the cells seeded on the 60% deformed samples, which were particularly designed in a specific geometry that could endure greater strain values. Overall, the current findings open a new venue for the production of metallic implants with enhanced biocompatibility, such that the adhesion and viability of the cells surrounding an implant can be optimized by tailoring the surface relief of the material, which is dictated by the micro-deformation mechanism activities facilitated by plastic deformation imposed by machining.

  16. Size effects in the elastic deformation behavior of metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Patrick; Peukert, Wolfgang, E-mail: W.Peukert@lfg.uni-erlangen.de [Friedrich-Alexander-University Erlangen-Nuremberg, Institute for Particle Technology (Germany)

    2012-12-15

    In this work, the results of a series of molecular statics simulations to investigate the size dependence of the elastic properties of metallic nanoparticles are presented. The per-atom stiffness tensor was calculated from the derivative of the used embedded atom method potentials and, from it, lower order elastic parameters, such as the Young's modulus or the Poisson ratio. The Young's modulus decayed up to 30 % relative to the bulk values for 2.5 nm small particles, whereas the Poisson ratio showed an increase with decreasing particle size for most materials. Particles with a diameter of 30 nm approached the continuum values to around 1 %, marking the transition to continuum theory. The size-dependent Young's modulus and several other material properties can be described by a simple algebraic function of the number of atoms per particle. By plotting the radial distribution of the local Young's modulus within particles of different size, it is shown that only the outermost 2-3 atomic layers are responsible for the size-dependent change of elastic properties. Within these layers, the average atomic stiffness was found to decay linearly and independent of the particle size.

  17. Phase engineering of monolayer transition-metal dichalcogenide through coupled electron doping and lattice deformation

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang, Bin; Lan, Guoqiang; Song, Jun, E-mail: jun.song2@mcgill.ca [Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0C5 (Canada); Guo, Yinsheng [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Mi, Zetian [Department of Electrical and Computer Engineering, McGill University, Montreal, Quebec H3A 0E9 (Canada)

    2015-11-09

    First-principles calculations were performed to investigate the phase stability and transition within four monolayer transition-metal dichalcogenide (TMD) systems, i.e., MX{sub 2} (M = Mo or W and X = S or Se) under coupled electron doping and lattice deformation. With the lattice distortion and electron doping density treated as state variables, the energy surfaces of different phases were computed, and the diagrams of energetically preferred phases were constructed. These diagrams assess the competition between different phases and predict conditions of phase transitions for the TMDs considered. The interplay between lattice deformation and electron doping was identified as originating from the deformation induced band shifting and band bending. Based on our findings, a potential design strategy combining an efficient electrolytic gating and a lattice straining to achieve controllable phase engineering in TMD monolayers was demonstrated.

  18. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  19. The 3-Dimensional q-Deformed Harmonic Oscillator and Magic Numbers of Alkali Metal Clusters

    CERN Document Server

    Bonatsos, Dennis; Raychev, P P; Roussev, R P; Terziev, P A; Bonatsos, Dennis

    1999-01-01

    Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3) > SOq(3) symmetry are compared to experimental data for alkali metal clusters, as well as to theoretical predictions of jellium models, Woods--Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. The 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry of systems of alkali metal clusters.

  20. The effect of tooling deformation on process control in multistage metal forming

    Science.gov (United States)

    Havinga, Jos; van den Boogaard, Ton

    2016-10-01

    Forming of high-strength steels leads to high loads within the production process. In multistage metal forming, the loads in different process stages are transferred to the other stages through elastic deformation of the stamping press. This leads to interactions between process steps, affecting the process forces in each stage and the final geometry of the product. When force measurements are used for control of the metal forming process, it is important to understand these interactions. In his work, interactions within an industrial multistage forming process are investigated. Cutting, deepdrawing, forging and bending steps are performed in the production process. Several test runs of a few thousand products each were performed to gather information about the process. Statistical methods are used to analyze the measurements. Based on the cross-correlation between the force measurements of different stages, it can be shown that the interactions between the process steps are caused by elastic deformation of the tooling and the stamping press.

  1. A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms

    KAUST Repository

    Gurses, Ercan

    2011-12-01

    In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall-Petch effects, the tension-compression asymmetry and the enhanced rate sensitivity. © 2011 Elsevier B.V. All rights reserved.

  2. Meso-scale analysis of deformation wave heating in metalized solid explosive

    Directory of Open Access Journals (Sweden)

    Gonthier K.A.

    2011-01-01

    Full Text Available Deformation induced heating of reactive solids is a physically complex process. As such, the effects of meso-structure, component thermomechanical properties, component mass fractions, and porosity on their impact response is not well-understood. In this study, an explicit, 2-D, Lagrangian finite and discrete element technique is used to examine thermomechanical fields in metal-explosive (aluminum-HMX particle mixtures due to piston supported uniaxial deformation waves. The meso-scale description uses a plane strain, thermoelastic-viscoplastic and friction constitutive theory to describe the motion and deformation of individual particles, and an energy consistent, penalty based method to describe inter-particle contact. The deformation response of material having an initial solid volume fraction of ΦS0 = 0.835 is characterized for different metal mass fractions and wave strengths. Predictions indicate that the response can be classified into strength dominated and pressure dominated regions depending on wave strength. Average thermomechanical fields that define the macro-scale wave structure are found to differ both qualitatively and quantitatively between the two regions.

  3. Development of wide-range constitutive equations for calculations of high-rate deformation of metals

    Directory of Open Access Journals (Sweden)

    Preston D.

    2011-01-01

    Full Text Available For development of models of strength and compressibility of metals in wide range of pressures (up to several megabar and strain rates ~ 1÷108 s−1, the method of dynamic tests is used. Since direct measurement of strength is impossible under complicated intensive high-rate loading, a formal model is created at first, and then it is updated basing on comparison with many experiments, which are sensitive to shear strength. Elastic-plastic, viscous-elastic-plastic and relaxation integral models became nowadays most commonly used. The basic unsolved problems in simulation of high-rate deformation of metals are mentioned in the paper.

  4. Shear bands in a bulk metallic glass after large plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Qu, D.D.; Wang, Y.B.; Liao, X.Z.; Shen, J. (Harbin); (Sydney)

    2012-10-23

    A transmission electron microscopy investigation is conducted to trace shear bands in a Zr{sub 53}Cu{sub 18.7}Ni{sub 12}Al{sub 16.3} bulk metallic glass after experiencing 4% plastic deformation. Shear band initiation, secondary shear band interactions, mature shear band broadening and the interactions of shear bands with shear-induced nanocrystals are captured. Results suggest that the plasticity of the bulk metallic glass is enhanced by complex shear bands and their interactions which accommodate large plastic strain and prevent catastrophic shear band propagation.

  5. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    Science.gov (United States)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  6. Modeling adsorption properties of structurally deformed metal-organic frameworks using structure-property map.

    Science.gov (United States)

    Jeong, WooSeok; Lim, Dae-Woon; Kim, Sungjune; Harale, Aadesh; Yoon, Minyoung; Suh, Myunghyun Paik; Kim, Jihan

    2017-07-25

    Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure-property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure-property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations. By mapping the experimental data points of deformed SNU-200, MOF-5, and Ni-MOF-74 onto this structure-property map, we show that the experimentally deformed MOFs share similar adsorption properties with their nearest neighbor crystalline structures. Once the nearest neighbor crystalline MOFs for a deformed MOF are selected from a structure-property map at a specific condition, then the adsorption properties of these MOFs can be successfully transformed onto the degraded MOFs, leading to a new way to obtain properties of materials whose structural information is lost.

  7. Inelastic Deformation of Metal Matrix Composites. Part 1; Plasticity and Damage Mechanisms

    Science.gov (United States)

    Majumdar, B. S.; Newaz, G. M.

    1992-01-01

    The deformation mechanisms of a Ti 15-3/SCS6 (SiC fiber) metal matrix composite (MMC) were investigated using a combination of mechanical measurements and microstructural analysis. The objectives were to evaluate the contributions of plasticity and damage to the overall inelastic response, and to confirm the mechanisms by rigorous microstructural evaluations. The results of room temperature experiments performed on 0 degree and 90 degree systems primarily are reported in this report. Results of experiments performed on other laminate systems and at high temperatures will be provided in a forthcoming report. Inelastic deformation of the 0 degree MMC (fibers parallel to load direction) was dominated by the plasticity of the matrix. In contrast, inelastic deformations of the 90 degree composite (fibers perpendicular to loading direction) occurred by both damage and plasticity. The predictions of a continuum elastic plastic model were compared with experimental data. The model was adequate for predicting the 0 degree response; however, it was inadequate for predicting the 90 degree response largely because it neglected damage. The importance of validating constitutive models using a combination of mechanical measurements and microstructural analysis is pointed out. The deformation mechanisms, and the likely sequence of events associated with the inelastic deformation of MMCs, are indicated in this paper.

  8. Deformation behavior of metallic glasses with shear band like atomic structure: a molecular dynamics study.

    Science.gov (United States)

    Zhong, C; Zhang, H; Cao, Q P; Wang, X D; Zhang, D X; Ramamurty, U; Jiang, J Z

    2016-08-02

    Molecular dynamics simulations were employed to investigate the plastic deformation within the shear bands in three different metallic glasses (MGs). To mimic shear bands, MG specimens were first deformed until flow localization occurs, and then the volume of the material within the localized regions was extracted and replicated. Homogeneous deformation that is independent of the size of the specimen was observed in specimens with shear band like structure, even at a temperature that is far below the glass transition temperature. Structural relaxation and rapid cooling were employed to examine the effect of free volume content on the deformation behavior. This was followed by detailed atomic structure analyses, employing the concepts of Voronoi polyhedra and "liquid-like" regions that contain high fraction of sub-atomic size open volumes. Results suggest that the total fraction of atoms in liquid-like regions is a key parameter that controls the plastic deformation in MGs. These are discussed in the context of reported experimental results and possible strategies for synthesizing monolithic amorphous materials that can accommodate large tensile plasticity are suggested.

  9. Effect of different heating methods on deformation of metal plate under upsetting mechanism in laser forming

    Science.gov (United States)

    Shi, Yongjun; Liu, Yancong; Yi, Peng; Hu, Jun

    2012-03-01

    In a laser forming process, different forming mechanisms have different deformation behaviors. The aim of laser forming is to acquire plane strain under an upsetting mechanism, while a plate undergoes a small bending deformation. In some industrial applications, the bending strain should not occur. To achieve high-precision forming, the deformation behaviors of a metal plate when an upsetting mechanism plays a dominant role are studied in the paper. Several heating methods are proposed to reduce the plane strain difference along the thickness direction and little bending deformation resulting from a small temperature difference between the top and bottom surfaces of the plate. The results show that negligible bending deformation and a uniform plastic plane strain field can be obtained by simultaneously heating the top and bottom surfaces with the same process parameters. A conventional scanning method needs a larger spot diameter and slower scanning speed under the upsetting mechanism, but a smaller spot diameter and quicker scanning speed may be selected using the simultaneous heating method, which can greatly widen the potential scope of process parameters.

  10. Closed Die Deformation Behavior of Cylindrical Iron-Alumina Metal Matrix Composites During Cold Sinter Forging

    Science.gov (United States)

    Prasanna Kumar, Undeti Jacob; Gupta, Pallav; Jha, Arun Kant; Kumar, Devendra

    2016-10-01

    The present paper aims to study the closed die deformation behavior of cylindrical Fe-Al2O3 metal matrix composites (MMCs). Closed die was manufactured by machining the high carbon steel block followed by oil quenching and then finishing. Samples sintered at a temperature of 1100 °C for 1 h were characterized with X-ray diffraction and scanning electron microscopy, which showed the formation of Fe, Al2O3 and nano size FeAl2O4 phases respectively. Density and hardness of the composite samples were determined after sintering. Closed die deformation studies of the prepared composite samples were carried under three different interfacial frictional conditions i.e. dry, solid lubricating and liquid lubricating. Hardness, density and metallographic characterizations were also done for the deformed samples. On comparing the micrographs of the samples before and after deformation it was revealed that in deformed specimens recrystallization has taken place due to the difference in the energy between the strained iron matrix and unstrained alumina reinforcement during closed die forging process. Experimental density of the samples was also verified with the theoretical density using the standard equations. It is expected that the results of the present investigations will be helpful in developing quality MMC components for wide industrial applications.

  11. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  12. Inspection and Reconstruction of Metal-Roof Deformation under Wind Pressure Based on Bend Sensors.

    Science.gov (United States)

    Yang, Liman; Cui, Langfu; Li, Yunhua; An, Chao

    2017-05-06

    Metal roof sheathings are widely employed in large-span buildings because of their light weight, high strength and corrosion resistance. However, their severe working environment may lead to deformation, leakage and wind-lift, etc. Thus, predicting these damages in advance and taking maintenance measures accordingly has become important to avoid economic losses and personal injuries. Conventionally, the health monitoring of metal roofs mainly relies on manual inspection, which unavoidably compromises the working efficiency and cannot diagnose and predict possible failures in time. Thus, we proposed a novel damage monitoring scheme implemented by laying bend sensors on vital points of metal roofs to precisely monitor the deformation in real time. A fast reconstruction model based on improved Levy-type solution is established to estimate the overall deflection distribution from the measured data. A standing seam metal roof under wind pressure is modeled as an elastic thin plate with a uniform load and symmetrical boundaries. The superposition method and Levy solution are adopted to obtain the analytical model that can converge quickly through simplifying an infinite series. The truncation error of this model is further analyzed. Simulation and experiments are carried out. They show that the proposed model is in reasonable agreement with the experimental results.

  13. Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    Science.gov (United States)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2004-01-01

    In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  14. Modelling plastic deformation of metals over a wide range of strain rates using irreversible thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Huang Mingxin; Rivera-Diaz-del-Castillo, Pedro E J; Zwaag, Sybrand van der [Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS, Delft (Netherlands); Bouaziz, Olivier, E-mail: mingxin.huang@arcelormittal.com [ArcelorMittal Maizieres, Research and Development, Voie Romaine-BP30320, 57283 Maizieres-les-Metz Cedex (France)

    2009-07-15

    Based on the theory of irreversible thermodynamics, the present work proposes a dislocation-based model to describe the plastic deformation of FCC metals over wide ranges of strain rates. The stress-strain behaviour and the evolution of the average dislocation density are derived. It is found that there is a transitional strain rate ({approx} 10{sup 4} s{sup -1}) over which the phonon drag effects appear, resulting in a significant increase in the flow stress and the average dislocation density. The model is applied to pure Cu deformed at room temperature and at strain rates ranging from 10{sup -5} to 10{sup 6} s{sup -1} showing good agreement with experimental results.

  15. Deforming analysis of sheet metal based on stereo vision and coordinate grid

    Institute of Scientific and Technical Information of China (English)

    Hongqin Wei; Dehong Yu; Xueyu Ruan; Youqing Wang

    2004-01-01

    A new approach based on stereo vision technology is introduced to analyze sheet metal deformation. By measuring the deformed circle grids that are printed on the sheet surface before forming, the strain distribution of the workpiece is obtained. The measurement and analysis results can be used to verify numerical simulation results and guide production. To get good accuracy,some new techniques are employed: camera calibration based on genetic algorithm, feature abstraction based on self-adaptive technology, image matching based on structure feature and camera modeling pre-constrains, and parameter calculation based on curve and surface optimization. The experimental values show that the approach proposed is rational and practical, which can provide better measurement accuracy with less time than the conventional method.

  16. Fast electronic relaxation in metal nanoclusters via excitation of coherent shape deformations: Circumventing a bottleneck

    CERN Document Server

    Kresin, V V; Kresin, Vitaly V.; Ovchinnikov, Yu. N.

    2006-01-01

    Electron-phonon relaxation in size-quantized systems may become inhibited when the spacing of discrete electron energy levels exceeds the magnitude of the phonon frequency. We show, however, that nanoclusters can support a fast nonradiative relaxation channel which derives from their distinctive ability to undergo Jahn-Teller shape deformations. Such a deformation represents a collective and coherent vibrational excitation and enables electronic transitions to occur without a multiphonon bottleneck. We analyze this mechanism for a metal cluster within the analytical framework of a three-dimensional potential well undergoing a spheroidal distortion. An expression for the time evolution of the distortion parameter is derived, the electronic level crossing condition formulated, and the probability of electronic transition at a level crossing is evaluated. An application to electron-hole recombination in a closed-shell aluminum cluster with 40 electrons shows that the short (~250 fs) excitation lifetime observed ...

  17. Revealing homogeneous plastic deformation in dendrite-reinforced Ti-based metallic glass composites under tension

    Science.gov (United States)

    Wu, F. F.; Wei, J. S.; Chan, K. C.; Chen, S. H.; Zhao, R. D.; Zhang, G. A.; Wu, X. F.

    2017-01-01

    The tensile plastic deformation of dendrite-reinforced Ti-based metallic glass composites (MGCs) was investigated. It was found that there is a critical normalized strain-hardening rate (NSHR) that determines the plastic stability of MGCs: if the NSHR is larger than the critical value, the plastic deformation of the MGCs will be stable, i.e. the necking and strain localization can be effectively suppressed, resulting in homogeneous plastic elongation. In addition, dendrite-reinforce MGCs are verified as being intrinsically ductile, and can be used as good coatings for improving the surface properties of pure titanium or titanium alloys. These findings are helpful in designing, producing, and using MGCs with improved performance properties. PMID:28195216

  18. Temperature dependence of dynamic deformation in FCC metals, aluminum and invar

    Science.gov (United States)

    Chen, Laura; Swift, D. C.; Austin, R. A.; Florando, J. N.; Hawreliak, J.; Lazicki, A.; Saculla, M. D.; Eakins, D.; Bernier, J. V.; Kumar, M.

    2017-01-01

    Laser-driven shock experiments were performed on fcc metals, aluminum and invar, at a range of initial temperatures from approximately 120-800 K to explore the effect of initial temperature on dynamic strength properties at strain rates reaching up to 107 s-1. In aluminum, velocimetry data demonstrated an increase of peak stress of the elastic wave, σE, with initial temperature. Alternatively, for invar, σE exhibits little-to-no decrease over the same initial temperature range. Aluminum's unusual deformation behavior is found to primarily be due to anharmonic vibrational effects. Differences in the magnetic structure of aluminum and invar can account for discrepancies in high rate deformation behavior.

  19. New intrinsic mechanism on gum-like superelasticity of multifunctional alloys.

    Science.gov (United States)

    Liu, Jia-Peng; Wang, Yan-Dong; Hao, Yu-Lin; Wang, Yunzhi; Nie, Zhi-Hua; Wang, Dong; Ren, Yang; Lu, Zhao-Ping; Wang, Jinguo; Wang, Haoliang; Hui, Xidong; Lu, Ning; Kim, Moon J; Yang, Rui

    2013-01-01

    Ti-Nb-based Gum Metals exhibit extraordinary superelasticity with ultralow elastic modulus, superior strength and ductility, and a peculiar dislocation-free deformation behavior, most of which challenge existing theories of crystal strength. Additionally, this kind of alloys actually displays even more anomalous mechanical properties, such as the non-linear superelastic behavior, accompanied by a pronounced tension-to-compression asymmetry, and large ductility with a low Poisson's ratio. Two main contradictory arguments exist concerning the deformation mechanisms of those alloys, i.e., formation of reversible nanodisturbance and reversible martensitic transformation. Herein we used the in-situ synchrotron high-energy X-ray scattering technique to reveal the novel intrinsic physical origin of all anomalous mechanical properties of the Ti-24Nb-4Zr-8Sn-0.10O alloy, a typical gum-like metal. Our experiments provide direct evidence on two different kinds of interesting, stress-induced, reversible nanoscale martensitic transitions, i.e., the austenitic regions with B2 structure transform to α″ martensite and those with BCC structure transform to δ martensite.

  20. Stress and temperature dependence of the avalanche dynamics during creep deformation of metallic glasses.

    Science.gov (United States)

    Herrero-Gómez, Carlos; Samwer, Konrad

    2016-09-22

    The understanding of the mesoscopic origin of plasticity in metallic glasses remains still an open issue. At the microscopic level, Shear Transformation Zones (STZ), composed by dozens of atoms, have been identified as the basic unit of the deformation process. Macroscopically, metallic glasses perform either homogeneous or inhomogeneous flow depending on the experimental conditions. However, the emergence of macroscopic behavior resulting from STZ interactions is still an open issue and is of great interest. In the current work we present an approach to analyze the different interaction mechanisms of STZ's by studying the statistics of the avalanches produced by a metallic glass during tensile creep deformation. We identified a crossover between different regimes of avalanches, and we analyzed the dependence of such crossover on the experimental conditions, namely stress and temperature. We interpret such crossover as a transition from 3D random STZ activity to localized 2D nano-shear bands. The experimental time at which the crossover takes place seems to depend on the overall strain and strain rate in the sample.

  1. Computed Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    Science.gov (United States)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and is carried with the macro-flow of the weld metal. By using CT images, a 3-dimensional (3D) image of the lead flow pattern can be reconstructed. CT imaging was found to be a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  2. Degradation and recovery of adhesion properties of deformed metal-polymer interfaces studied by laser induced delamination

    NARCIS (Netherlands)

    Fedorov, A. V.; van Tijum, R.; Vellinga, W. -P.; De Hosson, J. Th. M.

    2007-01-01

    Adhesion properties of polymer coatings on metals are of great interest in various industrial applications, including packaging of food and drinks. Particular interest is focused on polymer-metal interfaces that are subjected to significant deformations during manufacturing process. In this work ste

  3. Atomistic simulation study of the shear-band deformation mechanism in Mg-Cu metallic glasses

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2006-01-01

    We have simulated plastic deformation of a model Mg-Cu metallic glass in order to study shear banding. In uniaxial tension, we find a necking instability occurs rather than shear banding. We can force the latter to occur by deforming in plane strain, forbidding the change of length in one...... of the transverse directions. Furthermore, in most of the simulations a notch is used to initiate shear bands, which lie at a 45 degrees angle to the tensile loading direction. The shear bands are characterized by the Falk and Langer local measure of plastic deformation D-min(2), averaged here over volumes...... containing many atoms. The D-min(2) profile has a peak whose width is around 10 nm; this width is largely independent of the strain rate. Most of the simulations were, at least nominally, at 100 K, about T-g/3 for this system. The development of the shear bands takes a few tens of ps, once plastic flow has...

  4. Mechanisms of compressive deformation and failure of porous bulk metallic glasses

    Science.gov (United States)

    Gouripriya, S.; Tandaiya, Parag

    2017-06-01

    Bulk metallic glasses (BMGs) are a new class of engineering materials having strengths as high as 10 times that of conventional steels, but show no significant plastic strain at fracture. By introducing pores, their strain to failure has been shown to improve under uniaxial compression. In this work, three-dimensional finite element simulations of uniaxial compression are carried out on Pd-based porous BMGs having a wide range of pore volume fraction (1.9%-60%) with emphasis on understanding the underlying deformation and failure mechanisms. The resulting stress-strain curves agree reasonably well with existing experimental results. The simulations clearly bring out different failure mechanisms in low porosity BMGs and high porosity BMG foams. For low porosity BMGs (below 20%), the deformation and failure involves nucleation of shear bands around the pore diameter, linking of the shear bands with adjacent pores finally leading to initiation of ductile cracking within the shear bands. For high porosity BMG foams, the mechanism of deformation involves reduction in porosity of the material, self-contact of the pores, and their collapse on themselves causing densification of the material leading to apparent hardening in the stress strain behavior. The effect of pore geometry is also studied by considering ellipsoidal pores of volume fraction 3% and 11%. For ellipsoidal pores, the failure mechanisms are found to differ significantly when the orientation of the major axis of the pore vis-a-vis the loading axis is changed.

  5. Kinetics of transformation in an in-situ aluminum-strontium deformation processed metal-metal composite

    Science.gov (United States)

    Frerichs, Andrew Elliott

    2011-12-01

    Efficient electricity transmission is a key component in all plans to increase the amount of renewable power used in the decades ahead. Prime solar and wind generation sites are usually distant from major population centers, resulting in the need for improved conductor wires that are stronger, lighter, and have better conductivity than conventional conductors. Deformation processed metal-metal composites (DMMCs) have a desirable combination of high strength and good conductivity. One such DMMC, aluminum-strontium, was investigated in this study. The composite wire was created by extrusion, swaging, and wire drawing of bundled Al and Sr wires. Intermetallic compound formation between Al and Sr is of particular interest to produce a strong, conductive wire with good high-temperature strength. Samples of swaged and drawn Al-Sr composite wire were heat treated at 483K, 513K, 543K and 573K to produce samples at varying stages of intermetallic compound formation. Resistivity measurements were taken from samples over a range of heat treatment times and temperatures to calculate the activation energy for Al-Sr intermetallic compound formation. Scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction were used to investigate the changes in the microstructure occurring in the samples as a function of heat treatment. In addition, mechanical properties data were generated for pure Sr metal.

  6. Plasma Propulsion of a Metallic Microdroplet and its Deformation upon Laser Impact

    Science.gov (United States)

    Kurilovich, Dmitry; Klein, Alexander L.; Torretti, Francesco; Lassise, Adam; Hoekstra, Ronnie; Ubachs, Wim; Gelderblom, Hanneke; Versolato, Oscar O.

    2016-07-01

    The propulsion of a liquid indium-tin microdroplet by nanosecond-pulse laser impact is experimentally investigated. We capture the physics of the droplet propulsion in a scaling law that accurately describes the plasma-imparted momentum transfer over nearly three decades of pulse energy, enabling the optimization of the laser-droplet coupling. The subsequent deformation of the droplet is described by an analytical model that accounts for the droplet's propulsion velocity and the liquid properties. Comparing our findings to those from vaporization-accelerated millimeter-sized water droplets, we demonstrate that the fluid-dynamic response of laser-impacted droplets is scalable and decoupled from the propulsion mechanism. By contrast, the physics behind the propulsion of liquid-metal droplets differs from that of water. It is studied here in detail and under industrially relevant conditions as found in next-generation nanolithography machines.

  7. Deformed Harmonic Oscillators for Metal Clusters and Balian-Bloch Theory

    CERN Document Server

    Bonatsos, D; Raychev, P P; Terziev, P A; Bonatsos, Dennis

    2003-01-01

    The predictions for the shell structure of metal clusters of the three-dimensional q-deformed harmonic oscillator (3D q-HO), utilizing techniques of quantum groups and having the symmetry Uq(3)$\\supset$SOq(3), are compared to the restrictions imposed by the periodic orbit theory of Balian and Bloch, of electrons moving in a spherical cavity. It is shown that agreement between the predictions of the two models is established through the introduction of an additional term to the Hamiltonian of the 3D q-HO, which does not influence the predictions for supershells. This term preserves the Uq(3)$\\supset$SOq(3) symmetry, while in addition it can be derived through a variational procedure, analogous to the one leading from the usual harmonic oscillator to the Morse oscillator by introducing the concept of the Variable Frequency Oscillator (VFO).

  8. Acoustic softening in metals during ultrasonic assisted deformation via CP-FEM

    KAUST Repository

    Siddiq, Amir

    2011-01-01

    In this paper, a phenomenological crystal plasticity model is modified to account for acoustic (ultrasonic) softening effects based on the level of ultrasonic intensity supplied to single and polycrystalline metals. The material parameters are identified using the inverse modeling approach by interfacing the crystal plasticity model with an optimization tool. The proposed model is validated and verified by comparing the microstructure evolution with experimental EBSD results reported in the literature. The model is able to capture the ultrasonic softening effect and the results show that as the ultrasonic intensity increases, the plastic deformation also increases. Differences in the stress-strain response are explained based on the slip system orientation tensor (Schmidt factors) which depends upon the crystal orientation. © 2010 Elsevier B.V. All rights reserved.

  9. Deformation and failure of bulk metallic glasses under different initial temperatures

    Directory of Open Access Journals (Sweden)

    Li J.C.

    2015-01-01

    Full Text Available Based on the coupled thermo-mechanical model, a constitutive model for bulk metallic glasses (BMGs, which is generalized to the multi-axial stress state and considers the effects of free volume, heat and hydrostatic stress, has been modified in the present paper. Besides, a failure criterion of critical free volume concentration is introduced based on the coalescence mechanism of free volume. The constitutive model as well as the failure criterion is implemented into the LS-DYNA commercial software by user material subroutine (UMAT. Then FEM simulations for different initial material temperatures are conducted and the evolutions of material parameter as well as corresponding macroscopic mechanical behaviour of material are analyzed. Relative analysis shows that the initial material temperature significantly affects the deformation and failure of material.

  10. Observation and simulation of motion and deformation for impact-loaded metal cylinders

    Science.gov (United States)

    Hickman, R. J.; Wise, J. L.; Smith, J. A.; Mersch, J. P.; Robino, C. V.; Arguello, J. G.

    2017-01-01

    Complementary gas-gun experiments and computational simulations have examined the time-resolved motion and post-mortem deformation of cylindrical metal samples subjected to impact loading. The effect of propagation distance on a compressive waveform generated in a sample by planar impact at one end was determined using a velocity interferometer to track the longitudinal motion at the center of the opposing rear (i.e., free) surface. Samples (25.4-mm diameter) were fabricated from aluminum (types 6061 and 7075), copper (OFHC = oxygen free, high conductivity), stainless steel (type 316), and cobalt alloy L-605 (AMS 5759; also referenced as Haynes®25 alloy). For each material, waveforms obtained for a 25.4-mm long cylinder corresponded to two-dimensional strain at the measurement point. The wave-profile data have been analyzed to (i) establish key dynamic material modeling parameters, (ii) assess the functionality of the Sierra Solid Mechanics-Presto (Sierra/SM) code, and (iii) identify the need for additional testing, material modeling, and/or code development. The results of subsequent simulations have been compared to benchmark recovery experiments that showed the residual plastic deformation incurred by cylinders following end, side, and corner impacts.

  11. Observation and Simulation of Motion and Deformation for Impact-Loaded Metal Cylinders

    Science.gov (United States)

    Hickman, R. J.; Wise, J. L.; Smith, J. A.; Mersch, J. P.; Robino, C. V.; Arguello, J. G.

    2015-06-01

    Complementary gas-gun experiments and computational simulations have examined the time-resolved motion and post-mortem deformation of cylindrical metal samples subjected to impact loading. The effect of propagation distance on a compressive waveform generated in a sample by planar impact at one end was determined using a velocity interferometer to track the longitudinal motion of the opposing rear (i.e., free) surface. Samples (24 or 25.4-mm diameter) were fabricated from aluminum (types 6061 and 7075), copper, stainless steel (type 316), and cobalt alloy L-605 (AMS 5759). For each material, waveforms obtained for a short (2 mm) and a long (25.4 mm) cylinder corresponded, respectively, to one-dimensional (i.e., uniaxial) and two-dimensional strain at the measurement point. The wave-profile data have been analyzed to (i) establish key dynamic material modeling parameters, (ii) assess the functionality of the Sierra Solid Mechanics-Presto (SierraSM/Presto) code, and (iii) identify the need for additional testing, material modeling, and/or code development. The results of subsequent simulations have been compared to benchmark recovery experiments that showed the residual plastic deformation incurred by cylinders following end, side, and corner impacts. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  12. Mapping the Strain Distributions in Deformed Bulk Metallic Glasses Using Hard X-Ray Diffraction

    Science.gov (United States)

    Bednarcik, J.; Chen, L. Y.; Wang, X. D.; Jiang, J. Z.; Franz, H.

    2012-05-01

    The deformation behavior of Cu45 Zr46.5 Al7Ti1.5 bulk metallic glass (BMG) under bending was investigated in-situ using high-energy X-ray synchrotron diffraction. Samples were bent using two different benders with radii of 10 and 20 mm. The components of the strain tensor were determined from the change of positions of the first maximum of the diffracted intensity in reciprocal space. The procedure of data treatment was improved by the introduction of direct beam off-center correction. Comparing results for the two different bending radii, we found that the zero stress region does not necessarily lay within the central part of the specimen. Bending with smaller radius resulted in symmetric strain distribution, whereas a larger bending radius revealed strong asymmetry. Furthermore, bending with a smaller radius (10 mm) shows steeper strain gradients as compared with the situation in which the larger bending radius (20 mm) was used. Using a smaller bending radius implies reaching higher tensile/compressive stresses and reveals the signs of the plastic deformation, which are demonstrated as a saturation of elastic strains.

  13. Large deformation ionic polymer-metal composites actuators based on porous Nafion membranes

    Science.gov (United States)

    Zhao, Dongxu; Li, Dichen; Wang, Yanjie; Luo, Meng; Chen, Hualing

    2016-04-01

    With advantages of low driving voltage, good flexibility and high electromechanical efficiency, ionic polymer-metal composites (IPMCs), which are one of the most attractive smart materials, have been research hotspot in actuators, sensors and artificial muscles. However, a serious drawback of little deformation of thick IPMC actuator limits its application. In this paper, we fabricated thick porous Nafion membranes by freeze-drying process. A series of Thermogravimetric analyses (TGA), Field emission scanning electron microscopy (FE-SEM) and Water uptake (WUP) tests were performed to examine the validity of the freeze-drying process and the pore size and the porosity. Then, the porous IPMCs were fabricated with the freeze-drying processed Nafion membranes by the solution casting and reducing plating. Finally, the IPMC actuators with the dimensions of 25× 5× 1 in millimeters were achieved and tested. The terminal deformation of the porous IPMC actuator increased by 739.7%, compared with the ordinary IPMC actuator with the same dimensions under the driving voltage of 2VDC.

  14. Molecular Dynamics Simulation of Structural Characterization of Elastic and Inelastic Deformation in ZrCu Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Shidong Feng

    2014-01-01

    Full Text Available The nanoscopic deformation behaviors in a ZrCu metallic glass model during loading-unloading process under uniaxial compression have been analyzed on the basis of the molecular dynamics (MD. The reversible degree of shear origin zones (SOZs is used as the structural indicator to distinguish the elastic deformation and inelastic deformation of ZrCu metallic glass at the atomic level. We find that the formation of SOZs is reversible at the elastic stage but irreversible at the inelastic stage during the loading and unloading processes. At the inelastic stage, the full-icosahedra fraction in SOZs is quickly reduced with increased strain and the decreasing process is also irreversible during the unloading processes.

  15. Modelling of real area of contact between tool and workpiece in metal forming processes including the influence of subsurface deformation

    DEFF Research Database (Denmark)

    Nielsen, Chris Valentin; Martins, Paulo A. F.; Bay, Niels Oluf

    2016-01-01

    New equipment for testing asperity deformation at various normal loads and subsurface elongations is presented. Resulting real contact area ratios increase heavily with increasing subsurface expansion due to lowered yield pressure on the asperities when imposing subsurface normal stress parallel ...... for estimating friction in the numerical modelling of metal forming processes....

  16. Effect of rolling deformation on the microstructure of bulk Cu60Zr20Ti20 metallic glass and its crystallization

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Zhou, Y.H.;

    2006-01-01

    Bulk Cu60Zr20Ti20 metallic glass has been rolled at room temperature (RT) and cryogenic temperature (CIF) up to 97% in thickness reduction, and the dependences of microstructure on the strain and temperature have been investigated. It is revealed that as the deformation proceeds below a critical...

  17. Investigations into Deformation Characteristics during Open-Die Forging of SiCp Reinforced Aluminium Metal Matrix Composites

    Directory of Open Access Journals (Sweden)

    Deep Verma

    2013-01-01

    Full Text Available The deformation characteristics during open-die forging of silicon carbide particulate reinforced aluminium metal matrix composites (SiCp AMC at cold conditions are investigated. The material was fabricated by liquid stir casting method in which preheated SiC particles were mixed with molten LM6 aluminium casting alloy and casted in the silicon mould. Finally, preforms obtained were machined in required dimensions. Two separate cases of deformation, that is, open-die forging of solid disc and solid rectangular preforms, were considered. Both upper bound theoretical analysis and experimental investigations were performed followed by finite element simulation using DEFORM, considering composite interfacial friction law, barreling of preform vertical sides, and inertia effects, that is, effect of die velocity on various deformation characteristics like effective stress, strain, strain rate, forging load, energy dissipations, and height reduction. Results have been presented graphically and critically investigated to evaluate the concurrence among theoretical, experimental, and finite element based computational findings.

  18. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Directory of Open Access Journals (Sweden)

    K. K. Song

    2013-01-01

    Full Text Available The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-“double”-to-“triple”-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  19. Correlation between the microstructures and the deformation mechanisms of CuZr-based bulk metallic glass composites

    Science.gov (United States)

    Song, K. K.; Pauly, S.; Sun, B. A.; Tan, J.; Stoica, M.; Kühn, U.; Eckert, J.

    2013-01-01

    The variation of the transformation-mediated deformation behavior with microstructural changes in CuZr-based bulk metallic glass composites is investigated. With increasing crystalline volume fraction, the deformation mechanism gradually changes from a shear-banding dominated process as evidenced by a chaotic serrated flow behavior, to being governed by a martensitic transformation with a pronounced elastic-plastic stage, resulting in different plastic deformations evolving into a self-organized critical state characterized by the power-law distribution of shear avalanches. This is reflected in the stress-strain curves by a single-to-"double"-to-"triple"-double yielding transition and by different mechanical properties with different serrated flow characteristics, which are interpreted based on the microstructural evolutions and a fundamental energy theorem. Our results can assist in understanding deformation behaviors for high-performance metastable alloys.

  20. Finite Element Analysis for Effect of Roll Radius on Metal Deformation of Hot Rolling Plate

    Institute of Scientific and Technical Information of China (English)

    LUO De-xing; CHEN Qi-an; LIU Li-wen

    2005-01-01

    The deformation of rolling piece in hot rolling by flat roll with different radii is analyzed with three-dimensional large deformation thermo-mechanical coupling finite element method. The distribution laws of stress, strain and strain energy density in deformation zone with rolls of different radii were studied. The result indicated that under the same condition, the larger the roll radius is, the more vigorous the deformation in deformation zone is.

  1. Electron Beam Induced Artifacts During in situ TEM Deformation of Nanostructured Metals

    Science.gov (United States)

    Sarkar, Rohit; Rentenberger, Christian; Rajagopalan, Jagannathan

    2015-11-01

    A critical assumption underlying in situ transmission electron microscopy studies is that the electron beam (e-beam) exposure does not fundamentally alter the intrinsic deformation behavior of the materials being probed. Here, we show that e-beam exposure causes increased dislocation activation and marked stress relaxation in aluminum and gold films spanning a range of thicknesses (80-400 nanometers) and grain sizes (50-220 nanometers). Furthermore, the e-beam induces anomalous sample necking, which unusually depends more on the e-beam diameter than intensity. Notably, the stress relaxation in both aluminum and gold occurs at beam energies well below their damage thresholds. More remarkably, the stress relaxation and/or sample necking is significantly more pronounced at lower accelerating voltages (120 kV versus 200 kV) in both the metals. These observations in aluminum and gold, two metals with highly dissimilar atomic weights and properties, indicate that e-beam exposure can cause anomalous behavior in a broad spectrum of nanostructured materials, and simultaneously suggest a strategy to minimize such artifacts.

  2. Interpretation of viscous deformation of Zr-based bulk metallic glass alloys based on Nabarro-Herring creep model

    Science.gov (United States)

    Na, Young-Sang; Lee, Jong-Hoon

    2006-04-01

    Superplastic-like viscous deformation of bulk metallic glass alloys around the glass transition temperature (Tg) was analyzed based on the Nabarro-Herring creep model, a classical creep model, where the diffusional motion of atoms or vacancies through the lattice (atomic configuration) is considered. The amorphous matrix of bulk metallic glasses that has a randomly-packed atomic configuration was assumed to behave in a manner similar to the grain boundary in polycrystalline metals so as to approximate the diffusivity of the major constituent element. In spite of rough approximation of the parameters in the Nabarro-Herring creep equation, a reasonable value of the diffusion path (d) could be obtained from the experimentally-obtained metal flow data, including the steady state stress and the strain rate. Due to the absence of vacancy sources such as grain boundaries in homogeneous metallic glasses, the diffusion path, which, in polycrystalline materials, generally is the average distance between vacancy sources such as grain boundaries, was considered in this work as the average distance between tunneling centers in bulk metallic glass alloys. The calculated diffusion path was comparable to the density of tunneling centers around Tg, proposed by M. H. Cohen and G. S. Grest based on free volume theory. The calculated diffusion path showed monotonous decrease with temperature over Tg for Zr-based bulk metallic glass alloys. Based on this analysis, a schematic model for viscous deformation of bulk metallic glass was proposed.

  3. Unified description of magic numbers of metal clusters in terms of the 3-dimensional q-deformed harmonic oscillator

    CERN Document Server

    Bonatsos, Dennis; Lenis, D; Raychev, P P; Roussev, R P; Terziev, P A

    2000-01-01

    Magic numbers predicted by a 3-dimensional q-deformed harmonic oscillator with Uq(3)>SOq(3) symmetry are compared to experimental data for atomic clusters of alkali metals (Li, Na, K, Rb, Cs), noble metals (Cu, Ag, Au), divalent metals (Zn, Cd), and trivalent metals (Al, In), as well as to theoretical predictions of jellium models, Woods-Saxon and wine bottle potentials, and to the classification scheme using the 3n+l pseudo quantum number. In alkali metal clusters and noble metal clusters the 3-dimensional q-deformed harmonic oscillator correctly predicts all experimentally observed magic numbers up to 1500 (which is the expected limit of validity for theories based on the filling of electronic shells), while in addition it gives satisfactory results for the magic numbers of clusters of divalent metals and trivalent metals, thus indicating that Uq(3), which is a nonlinear extension of the U(3) symmetry of the spherical (3-dimensional isotropic) harmonic oscillator, is a good candidate for being the symmetry ...

  4. The influence of metallic shell deformation on the contact mechanics of a ceramic-on-ceramic total hip arthroplasty.

    Science.gov (United States)

    Qiu, Changdong; Wang, Ling; Li, Dichen; Jin, Zhongmin

    2016-01-01

    Total hip arthroplasty of ceramic-on-ceramic bearing combinations is increasingly used clinically. The majority of these implants are used with cementless fixation that a metal-backing shell is press-fitted into the pelvic bone. This usually results in the deformation of the metallic shell, which may also influence the ceramic liner deformation and consequently the contact mechanics between the liner and the femoral head under loading. The explicit dynamic finite element method was applied to model the implantation of a cementless ceramic-on-ceramic with a titanium shell and subsequently to investigate the effect of the metallic shell deformation on the contact mechanics. A total of three impacts were found to be necessary to seat the titanium alloy shell into the pelvic bone cavity with a 1 mm diameter interference and a 1.3 kg impactor at 4500 mm s(-1) velocity. The maximum deformation of the metallic shell was found to be 160 µm in the antero-superior and postero-inferior direction and 97 µm in the antero-inferior and postero-superior direction after the press-fit. The corresponding values were slightly reduced to 67 and 45 µm after the ceramic liner was inserted and then modified to 74 and 43 µm under loading, respectively. The maximum deformation and the maximum principal stress of the ceramic liner were 31 µm and 144 MPa (tensile stress), respectively, after it was inserted into the shell and further increased to 52 µm and 245 MPa under loading. This research highlights the importance of the press-fit of the metallic shell on the contact mechanics of the ceramic liner for ceramic-on-ceramic total hip arthroplasties and potential clinical performances.

  5. Periodontal (Gum) Disease: Causes, Symptoms, and Treatments

    Science.gov (United States)

    ... for providing oral care. NIDCR > OralHealth > Topics > Gum (Periodontal) Diseases > Periodontal (Gum) Disease: Causes, Symptoms, and Treatments Periodontal ( ... U.S. currently have some form of the disease. Periodontal diseases range from simple gum inflammation to serious disease ...

  6. Ultra-Thin Deformable Silicon Substrates with Lateral Segmentation and Flexible Metal Interconnect

    NARCIS (Netherlands)

    Zoumpouidis, T.; Wang, L.; Bartek, M.; Jansen, K.M.B.; Ernst, L.J.

    2007-01-01

    Our progress in developing technology modules for deformable single-crystalline-silicon electronics is presented in this contribution. Additional deformability/reliability is accomplished by modifications of the previously reported ultra-thin and flexible CIRCONFLEX technology (1). The flexibility

  7. Roles of nanoclusters in shear banding and plastic deformation of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Nieh, T G

    2012-07-31

    During the course of this research we published 33 papers in various physics/material journals. We select four representing papers in this report and their results are summarized as follows. I. To study shear banding process, it is pertinent to know the intrinsic shear strain rate within a propagating shear band. To this aim, we used nanoindentation technique to probe the mechanical response of a Au49Ag5.5Pd2.3Cu26.9Si16.3 bulk metallic glass in locality and found notable pop-in events associated with shear band emission. Using a free volume model and under the situation when temperature and stress/hardness are fixed result in an equation, which predicts that hardness serration caused by pop-in decreases exponentially with the strain rate. Our data are in good agreement with the prediction. The result also predicts that, when strain rate is higher than a critical strain rate of 1700 s^-1, there will be no hardness serration, thereby no pop-in. In other words, multiple shear bandings will take place and material will flow homogeneously. The critical strain rate of 1700 s^-1 can be treated as the intrinsic strain rate within a shear band. We subsequently carried out a simulation study and showed that, if the imposed strain rate was over , the shear band spacing would become so small that the entire sample would virtually behave like one major shear band. Using the datum strain rate =1700 s^-1 and based on a shear band nucleation model proposed by us, the size of a shear-band nucleus in Au-BMG was estimated to be 3 10^6 atoms, or a sphere of ~30 nm in diameter. II. Inspired by the peculiar result published in a Science article Super Plastic Bulk Metallic Glasses at Room Temperature, we synthesized the Zr-based bulk metallic glass with a composition identical to that in the paper (Zr64.13Cu15.75Ni10.12Al10) and, subsequently, tested in compression at the same slow strain rate (~10^-4 s^-1). We found that the dominant deformation mode is always single shear. The stress

  8. On the deformation mechanisms and electrical behavior of highly stretchable metallic interconnects on elastomer substrates

    Science.gov (United States)

    Arafat, Yeasir; Dutta, Indranath; Panat, Rahul

    2016-09-01

    Flexible metallic interconnects are highly important in the emerging field of deformable/wearable electronics. In our previous work [Arafat et al., Appl. Phys. Lett. 107, 081906 (2015)], interconnect films of Indium metal, periodically bonded to an elastomer substrate using a thin discontinuous/cracked adhesion interlayer of Cr, were shown to sustain a linear strain of 80%-100% without failure during repeated cycling. In this paper, we investigate the mechanisms that allow such films to be stretched to a large strain without rupture along with strategies to prevent a deterioration in their electrical performance under high linear strain. Scanning Electron Microscopy and Digital Image Correlation are used to map the strain field of the Cr adhesion interlayer and the In interconnect film when the elastomer substrate is stretched. It is shown that the Cr interlayer morphology, consisting of islands separated by bi-axial cracks, accommodates the strain primarily by widening of the cracks between the islands along the tensile direction. This behavior is shown to cause the strain in the In interconnect film to be discontinuous and concentrated in bands perpendicular to the loading direction. This localization of strain at numerous periodically spaced locations preempts strain-localization at one location and makes the In film highly stretchable by delaying rupture. Finally, the elastic-plastic mismatch-driven wrinkling of the In interconnect upon release from first loading cycle is utilized to delay the onset of plasticity and allow the interconnect to be stretched repeatedly up to 25% linear strain in subsequent cycles without a deterioration of its electrical performance.

  9. Chewing gums for optimal health

    Directory of Open Access Journals (Sweden)

    Nidhi Madan

    2011-01-01

    Full Text Available This article elaborates on the general aspects and health benefits of chewing gum. Chewing gums have been used since the time of prehistoric man as a source of entertainment and relaxation. It has also become a trendsetter with the teenagers. Currently, the health benefits of chewing gums are being studied and used in the treatment of various diseases. Certain medications have also been included in gums to act as an alternative drug delivery system. These gums have been found to be successful for the treatment of diseases, such as peptic ulcers, upper digestive tract cancer, oral candidiasis, and so on. It helps to relieve symptoms of xerostomia, Parkinsonism, tooth sensitivity after bleaching, and oral malodor. It helps in maintaining oral health, relieves stress, helps in weight loss, and improves alertness. Chewing gum may be distracting and irritating in numerous social environments, including schools, colleges, and the workplace. Research into the social effects of chewing gums is also necessary to further our knowledge into the psychosocial aspects of these gums.

  10. Features of deformation of metal body surfaces under impact of a water jet

    Science.gov (United States)

    Aganin, A. A.; Khismatullina, N. A.

    2016-01-01

    The paper presents a mathematical model and computational results on dynamics of a perfect elastic-plastic body under the load arising during impact of a high-velocity liquid jet with the hemispherical end. The body is simulated by the isotropic linearly-elastic semi-space, its plastic state is described by the von Mises condition. The dependence of features of the body surface deformation on the body material is studied. The problem is considered in the axisymmetric statement. The axis of symmetry is that of the jet. The loaded domain is a circle with its radius rapidly growing from zero to the jet radius. The pressure in the loaded domain is non-uniform both in time and space. Three metal alloys (aluminium, copper-nickel and steel) are considered as the body material. The loading of the body surface in all the cases corresponds to the impact of a water jet with the radius 100 pm and the velocity 300 m/s. It has been shown that under such impact a nanometer pit arises on the body surface at the center of the domain of the jet action. The profile of the pit and its maximal depth depend on the body material.

  11. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.T.; Hong, S.H.; Lee, C.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, J.M., E-mail: jinman_park@hotmail.com [Materials Research Center, Samsung Advanced Institute of Technology (SAIT), San 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); Kim, T.W.; Lee, W.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yim, H.I. [Department of Physics, Sookmyung Women’s University, Hyochangwongil 52, Yongsan-ku, Seoul 140-742 (Korea, Republic of); Kim, K.B., E-mail: kbkim@sejong.ac.kr [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2014-02-25

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe{sub 52}Co{sub 20−x}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub x} alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe{sub 52}Co{sub 17}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub 3} bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept.

  12. Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

    Directory of Open Access Journals (Sweden)

    Dianyu Wu

    2015-11-01

    Full Text Available The microstructures and mechanical properties of (Cu0.5Zr0.5100−xZnx (x = 0, 1.5, 2.5, 4.5, 7, 10, and 14 at. % bulk metallic glass (BMG composites were studied. CuZr martensitic crystals together with minor B2 CuZr and amorphous phases dominate the microstructures of the as-quenched samples with low Zn additions (x = 0, 1.5, and 2.5 at. %, while B2 CuZr and amorphous phases being accompanied with minor martensitic crystals form at a higher Zn content (x = 4.5, 7, 10, and 14 at. %. The fabricated Cu-Zr-Zn BMG composites exhibit macroscopically appreciable compressive plastic strain and obvious work-hardening due to the formation of multiple shear bands and the deformation-induced martensitic transformation (MT within B2 crystals. The present BMG composites could be a good candidate as high-performance structural materials.

  13. Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

    Science.gov (United States)

    Scholze, M.; Kolonko, A.; Lindner, T.; Lampke, T.; Helbig, F.

    2016-03-01

    This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

  14. Strength and deformability of concrete beams reinforced by non-metallic fiber and composite rebar

    Science.gov (United States)

    Kudyakov, K. L.; Plevkov, V. S.; Nevskii, A. V.

    2015-01-01

    Production of durable and high-strength concrete structures with unique properties has always been crucial. Therefore special attention has been paid to non-metallic composite and fiber reinforcement. This article describes the experimental research of strength and deformability of concrete beams with dispersed and core fiber-based reinforcement. As composite reinforcement fiberglass reinforced plastic rods with diameters 6 mm and 10 mm are used. Carbon and basalt fibers are used as dispersed reinforcement. The developed experimental program includes designing and production of flexural structures with different parameters of dispersed fiber and composite rebar reinforcement. The preliminary testing of mechanical properties of these materials has shown their effectiveness. Structures underwent bending testing on a special bench by applying flexural static load up to complete destruction. During the tests vertical displacements were recorded, as well as value of actual load, slippage of rebars in concrete, crack formation. As a result of research were obtained structural failure and crack formation graphs, value of fracture load and maximum displacements of the beams at midspan. Analysis of experimental data showed the effectiveness of using dispersed reinforcement of concrete and the need for prestressing of fiberglass composite rebar.

  15. In-situ deformation studies of an aluminum metal-matrix composite in a scanning electron microscope

    Science.gov (United States)

    Manoharan, M.; Lewandowski, J. J.

    1989-01-01

    Tensile specimens made of a metal-matrix composite (cast and extruded aluminum alloy-based matrix reinforced with Al2O3 particulate) were tested in situ in a scanning electron microscope equipped with a deformation stage, to directly monitor the crack propagation phenomenon. The in situ SEM observations revealed the presence of microcracks both ahead of and near the crack-tip region. The microcracks were primarily associated with cracks in the alumina particles. The results suggest that a region of intense deformation exists ahead of the crack and corresponds to the region of microcracking. As the crack progresses, a region of plastically deformed material and associated microcracks remains in the wake of the crack.

  16. Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

    2016-09-15

    To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

  17. Reformation Capability of Short-Range Order and Their Medium-Range Connections Regulates Deformability of Bulk Metallic Glasses

    Science.gov (United States)

    Li, Congling; Wei, Yujie; Shi, Xinghua

    2015-07-01

    Metallic glasses (MGs) typically have high yield strength while low ductility, and the latter is commonly considered as the Achilles’ heel of MGs. Elucidate the mechanism for such low ductility becomes the research focus of this field. With molecular level simulations, we show the degree of short-range order (SRO) of atomic structure for brittle Fe-based glass decreases dramatically during the stretch, while mild change occurs in ductile Zr-based glass. The reformation capability for SRO and their medium-range connections is found to be the primary characteristics to differentiate the deformability between the two metallic glasses. We suspect that, in addition to the strength of networks formed by SRO structure, the reformation capability to reform SRO networks also plays the key role in regulating the ductility in metallic glasses. Our study provides important insights into the understanding about the mechanisms accounting for ductility or brittleness of bulk metallic glasses.

  18. Photosensitivity of heterojunctions formed by deposition of gum on a layered III VI semiconductor

    Science.gov (United States)

    Drapak, S. I.; Kovalyuk, Z. D.

    2007-09-01

    The list of materials showing promise for the production of photosensitive structures is extended to include an organic material of biological origin known as gum. The current-voltage characteristics of hetero-junctions formed by a gum layer and a layered semiconductor (InSe, GaSe) are studied. An attempt is made to relate some spectral features of the relative quantum efficiency of the structures (for example, nonzero photosensitivity beyond the fundamental absorption edge of the semiconductor material) to the deformation interaction between the condensed gum layer and the layered III VI semiconductor surface.

  19. Production of Gum from Cashew Tree Latex

    Directory of Open Access Journals (Sweden)

    O. S. AZEEZ

    2005-06-01

    Full Text Available This research is aimed at producing gum from cashew tree latex, which can act as substitute for gum Arabic. The method used include drying and size reduction of the exudates gum, sieving of the gum to remove impurities, dissolution of the gum in distilled water, filtration to remove polysaccharide waste and finally concentration and stability of the gum. Glycerine, starch and Zinc oxide are some of the additives used in stabilizing the gum. The pH and Viscosity on addition of various percentage concentration of stabilizing agent were determined. Gum of the best quality was obtained with viscosity and pH of 4.52 Ns/m2 and 4.2 respectively; this is because the natural pH of gum from Acacia Senegal ranges between 3.9 - 4.9. The gum can be used as an alternative for synthetic adhesive used presently for stamps and envelopes.

  20. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    DEFF Research Database (Denmark)

    Trinkaus, H.; Singh, Bachu Narain

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly...

  1. Experimental studies on the deformation and rupture of thin metal plates subject to underwater shock wave loading

    Directory of Open Access Journals (Sweden)

    Chen Pengwan

    2015-01-01

    Full Text Available In this paper, the dynamic deformation and rupture of thin metal plates subject to underwater shock wave loading are studied by using high-speed 3D digital image correlation (3D-DIC. An equivalent device consist of a gas gun and a water anvil tube was used to supplying an exponentially decaying pressure in lieu of explosive detonation which acted on the panel specimen. The thin metal plate is clamped on the end of the shock tube by a flange. The deformation and rupture process of the metal plates subject to underwater shock waves are recorded by two high-speed cameras. The shape, displacement fields and strain fields of the metal plates under dynamic loading are obtained by using VIC-3D digital image correlation software. The strain gauges also were used to monitor the structural response on the selected position for comparison. The DIC data and the strain gauges results show a high level of correlation, and 3D-DIC is proven to be an effective method to measure 3D full-field dynamic response of structures under underwater impact loading. The effects of pre-notches on the failure modes of thin circular plate were also discussed.

  2. Relation between icosahedral short-range ordering and plastic deformation in Zr-Nb-Cu-Ni-Al bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Z.W. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Gu, L. [WPI, Advance Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Xie, G.Q. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Zhang, W., E-mail: wzhang@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [WPI, Advance Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Zhang, H.F., E-mail: hfzhang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Hu, Z.Q. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-04-15

    The relation between icosahedral short-range ordering (ISRO) and plastic deformation was investigated in Zr{sub 70-x}Nb{sub x}Cu{sub 13.5}Ni{sub 8.5}Al{sub 8} (at.%, x = 0, 2, 4, 6, 7, 8, 10) bulk metallic glasses (BMG). The formation of icosahedral quasicrystal (I-phase) during the annealing process implies that ISRO widely exists in these materials. The degree of ISRO is thermodynamically evaluated to show that ISRO increases with increasing Nb content. Compression tests indicate that BMG with 0-7 at.% Nb possess similar unusual plastic deformability, which is attributed to ISRO-mediated local distribution of free volume (FV) and ISRO prompted deformation-induced crystallization. A proposed core-shell model coupled with transmission electron microscopy analysis demonstrates that the FV is distributed more heterogeneously with increasing ISRO, which is beneficial for multiplying the shear bands. Deformation-induced crystallization is facilitated, owing to the low interfacial energy of the nucleation and growth of the crystals attributed to ISRO in the amorphous matrix, which improves plasticity by consuming energy and the product altering the stress field in the amorphous matrix. Design of new ductile BMG is discussed in these strategies.

  3. Base deformation of full metal-jacketed rifle bullets as a measure of impact velocity and range of fire.

    Science.gov (United States)

    Haag, Lucien C

    2015-03-01

    Full metal-jacketed rifle bullets with lead cores and open bases can experience deformation of their cylindrical shapes as they yaw during the penetration of soft tissues. The amount of deformation depends upon the strength of the bullet and the velocity in soft tissue when they go into yaw. The yaw behavior of a bullet in soft tissue depends upon its design (length, ogive shape, ogive length, center of gravity, and pre-impact stability) as it penetrates soft tissue. The yaw characteristics of common spitzer-type military rifle bullets are relatively well known and quite reproducible when fired into suitable soft tissue simulants. This, in turn, results in a relationship between the amount of deformation of the bullet's shank and impact velocity with soft tissue. The specific relationship between impact velocity and bullet deformation must be worked out through empirical testing, but this relationship can be of critical importance in determining impact velocity, which, in turn, relates to range of fire.

  4. Modeling of dislocation generation and interaction during high-speed deformation of metals

    DEFF Research Database (Denmark)

    Schiøtz, J.; Leffers, T.; Singh, B.N.

    2002-01-01

    at very high strain rates. We have used molecular-dynamics simulations to investigate high-speed deformation of copper crystals. Even though no pre-existing dislocation sources are present in the initial system, dislocations are quickly nucleated and a very high dislocation density is reached during...... the deformation. Due to the high density of dislocations, many inelastic interactions occur between dislocations, resulting in the generation of vacancies. After the deformation, a very high density of vacancies is observed, in agreement with the experimental observations. The processes responsible...

  5. A Density Functional Theory Study on the Deformation Behaviors of Fe-Si-B Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Guang-Ping Zheng

    2012-08-01

    Full Text Available Density functional theory has been employed to investigate the deformation behaviors of glassy Fe-Si-B model systems prepared by ab initio molecular dynamics. The atomistic deformation defects which are closely related to the local dilation volumes or excess volumes and unstable bonding have been systematically analyzed. It has been found that the icosahedral structures are relatively stable under shear deformation until fracture occurs. Plastic flow is indicated by interruption of percolating icosahedral structures, caused by unstable Fe-Si bonding of p-s hybridization in nature.

  6. Electromagnetic emission in the development of macroscopically unstable plastic deformation of a metal

    Science.gov (United States)

    Shibkov, A. A.; Titov, S. A.; Zheltov, M. A.; Gasanov, M. F.; Zolotov, A. E.; Proskuryakov, K. A.; Zhigachev, A. O.

    2016-01-01

    Electromagnetic emission accompanying the serrated deformation of the aluminum‒magnesium alloy Al-6Mg has been revealed and studied experimentally. By means of high-speed video recording and a complex of methods for measuring the strain, load, and electric potential, it has been found that there is a relation between the electromagnetic emission signals and the dynamics of deformation bands. Possible mechanisms of the generation of electromagnetic signals have been discussed.

  7. Inelastic deformation of metal matrix composites: Plasticity and damage mechanisms, part 2

    Science.gov (United States)

    Majumdar, B. S.; Newaz, G. M.

    1992-01-01

    The inelastic deformation mechanisms for the SiC (SCS-6)/Ti-15-3 system were studied at 538 C (1000 F) using a combination of mechanical measurements and detailed microstructural examinations. The objectives were to evaluate the contributions of plasticity and damage to the overall MMC response, and to compare the room temperature and elevated temperature deformation behaviors. Four different laminates were studied: (0)8, (90)8,(+ or -45)2s, and (0/90)2s, with the primary emphasis on the unidirectional (0)8, and (90)8 systems. The elevated temperature responses were similar to those at room temperature, involving a two-stage elastic-plastic type of response for the (0)8 system, and a characteristic three-stage deformation response for the (90)8 and (+ or -45)2s systems. The primary effects of elevated temperatures included: (1) reduction in the 'yield' and failure strengths; (2) plasticity through diffused slip rather than concentrated planar slip (which occurred at room temperature); and (3) time-dependent deformation. The inelastic deformation mechanism for the (0)8 MMC was dominated by plasticity at both temperatures. For the (90)8 and (+ or -45)2s MMCs, a combination of damage and plasticity contributed to the deformation at both temperatures.

  8. Irradiation depolymerized guar gum as partial replacement of gum Arabic for microencapsulation of mint oil.

    Science.gov (United States)

    Sarkar, Shatabhisa; Gupta, Sumit; Variyar, Prasad S; Sharma, Arun; Singhal, Rekha S

    2012-11-06

    Spray dried microcapsules of mint oil were prepared using gum Arabic alone and its blends with radiation or enzymatically depolymerized guar gum as wall materials. Microcapsules were evaluated for retention of mint oil during 8-week storage during which qualitative changes in encapsulated mint oil was monitored using principal component analysis. The microcapsules with radiation depolymerized guar gum as wall material component could better retain major mint oil compounds such as menthol and isomenthol. The t(1/2) calculated for mint oil in microcapsules of gum Arabic, gum Arabic:radiation depolymerized guar gum (90:10), gum Arabic:enzyme depolymerized guar gum (90:10) was 25.66, 38.50, and 17.11 weeks, respectively. The results suggested a combination of radiation depolymerized guar gum and gum Arabic to show better retention of encapsulated flavour than gum Arabic alone as wall material.

  9. Physically-Based and Power-Law Constitutive Relations for Higher Temperature Metal Processing and Creep-Type Deformations

    Science.gov (United States)

    Armstrong, R. W.; Balasubramanian, N.

    2017-02-01

    There is continuing research interest in the development and use of constitutive relations for assistance with description and optimization of higher temperature metal and alloy processing conditions and desired mechanical property performances, particularly in the latter case for nanopolycrystalline materials under creep-type loading deformations. Here, we focus on the plastic flow stress dependence on strain rate, temperature, and especially, on material grain size. Connection is established between, on the one hand, relatively recent thermal-activation-based relations for dislocation motion and, on the other hand, comparative power law expressions.

  10. Effect of the cooling rate on plastic deformability of a Zr-based bulk metallic glass

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The present work found the plastic deformability of Zr65Cu17.5Ni10Al7.5 BMG dependent on the cooling rate during the formation from the molten state alloy. The deformation behavior in the compression test of φ 2 mm Zr65Cu17.5Ni10Al7.5 BMGs as-cast or lathed from different sizes as-cast samples was characterized, and they exhibited different plastic strains. The compressive plastic strain increases with the decreasing diameter of the as-cast specimens, i.e. with increasing the cooling rate. It is suggested that free volume content in the BMGs, which is related to the cooling rate during the rapid solidification, could play an important role in the deformation process of the BMGs.

  11. Compression-induced deformation of individual metal-organic framework microcrystals.

    Science.gov (United States)

    Su, Zhi; Miao, Yu-Run; Mao, Shi-Min; Zhang, Guang-Hui; Dillon, Shen; Miller, Jeffrey T; Suslick, Kenneth S

    2015-02-11

    The deformation and mechanical behavior of individual zeolitic-imidazolate framework (ZIF-8) micro- and sub-microcrystals were observed under compression. Young's modulus and volume changes as a function of applied pressure were determined on individual single crystals, offering insights in the relationship among structure, morphology, and mechanical properties. Dramatic volume decreases and amorphization were detected during compression over a pressure range of 0-4 GPa for individual 1.2 μm ZIF-8 microcrystals, and the deformed microcrystals partially recovered after pressure release. The orientation and size effects on the mechanical behavior of ZIF-8 nano- and microcrystals were also investigated. The presence of solvates within the pores of the ZIF-8 has a dramatic effect on the mechanical properties of the single crystals. Methanol-solvated ZIF-8 microcrystals are much less deformable than the desolvated microcrystals and shatter completely at very low applied force.

  12. Effect of the severe plastic deformation temperature on the diffusion properties of the grain boundaries in ultrafine-grained metals

    Science.gov (United States)

    Chuvil'deev, V. N.; Myshlyaev, M. M.; Nokhrin, A. V.; Kopylov, V. I.; Lopatin, Yu. G.; Pirozhnikova, O. E.; Piskunov, A. V.; Semenycheva, A. V.; Bobrov, A. A.

    2017-05-01

    A model is proposed to explain the effect of the severe plastic deformation (SPD) temperature on the diffusion properties of the grain boundaries in ultrafine-grained (UFG) metals and alloys. It is shown that an increase in the SPD temperature in UFG metals leads to an increase in the activation energy of grainboundary diffusion from (3-5) k B T m, which corresponds to the diffusion parameters of nonequilibrium grain boundaries, to (8-10) k B T m, which corresponds to the diffusion parameters of equilibrium grain boundaries ( k B is the Boltzmann constant, T m is the melting temperature). The dependence of the activation energy of grain-boundary diffusion on the SPD temperature is found to be determined by the kinetics of the competing processes of defect accumulation at grain boundaries and the diffusion accommodation of defects.

  13. Spontaneous symmetry breaking and strong deformations in metal adsorbed graphene sheets

    Science.gov (United States)

    Jalbout, A. F.; Ortiz, Y. P.; Seligman, T. H.

    2013-03-01

    We study the adsorption of Li to graphene flakes simulated as aromatic molecules. Surprisingly the out of plane deformation is much stronger for the double adsorption from both sides to the same ring than for a single adsorption, although a symmetric solution seems possible. We thus have an interesting case of spontaneous symmetry breaking. While we cannot rule out a Jahn Teller deformation with certainty, this explanation seems unlikely and other options are discussed. We find a similar behavior for boron-nitrogen sheets, and also for other light alkalines as adsorbants.

  14. Spontaneous Symmetry Breaking and Strong Deformations in Metal Adsorbed Graphene Sheets

    CERN Document Server

    Jalbout, A F; Seligman, T H

    2013-01-01

    We study the adsorption of Li to graphene flakes described as aromatic molecules. Surprisingly the out of plane deformation is much stronger for the double adsorption from both sides to the same ring than for a single adsorption, although a symmetric solution seems possible. We thus have an interesting case of spontaneous symmetry breaking. While we cannot rule out a Jahn Teller deformation with certainty, this explanation seems unlikely and other options are discussed. We find a similar behavior for Boron-Nitrogen sheets, and also for other light alkalines.

  15. Deformation behavior of metallic glass composites reinforced with shape memory nanowires studied via molecular dynamics simulations

    Science.gov (United States)

    Şopu, D.; Stoica, M.; Eckert, J.

    2015-05-01

    Molecular dynamics simulations indicate that the deformation behavior and mechanism of Cu64Zr36 composite structures reinforced with B2 CuZr nanowires are strongly influenced by the martensitic phase transformation and distribution of these crystalline precipitates. When nanowires are distributed in the glassy matrix along the deformation direction, a two-steps stress-induced martensitic phase transformation is observed. Since the martensitic transformation is driven by the elastic energy release, the strain localization behavior in the glassy matrix is strongly affected. Therefore, the composite materials reinforced with a crystalline phase, which shows stress-induced martensitic transformation, represent a route for controlling the properties of glassy materials.

  16. On the applicability of deformed jellium model to the description of metal clusters

    DEFF Research Database (Denmark)

    Lyalin, Andrey G.; Matveentsev, Anton; Solov'yov, Ilia;

    2003-01-01

    This work is devoted to the elucidation the applicability of jellium model to the description of alkali cluster properties on the basis of comparison the jellium model results with those derived from experiment and within ab initio theoretical framework. On the basis of the Hartree-Fock and local......-density approximation deformed jellium model we have calculated the binding energies per atom, ionization potentials, deformation parameters and the optimized values of the Wigner-Seitz radii for neutral and singly charged sodium clusters with the number of atoms $N0$. These characteristics are compared...

  17. Take Care of Your Teeth and Gums

    Science.gov (United States)

    ... drink alcohol, drink only in moderation. What causes tooth decay and gum disease? Plaque (“plak”) is a sticky ... your teeth too long, it can lead to tooth decay and gum disease. Brushing and flossing help get ...

  18. Diabetes, Gum Disease, and Other Dental Problems

    Science.gov (United States)

    ... sugars or starches. Some types of plaque cause tooth decay or cavities. Other types of plaque cause gum ... in your mouth, which raises your risk for tooth decay and gum disease dry feeling in your mouth, ...

  19. Anion Effects on the Ion Exchange Process and the Deformation Property of Ionic Polymer Metal Composite Actuators

    Directory of Open Access Journals (Sweden)

    Wataru Aoyagi

    2016-06-01

    Full Text Available An ionic polymer-metal composite (IPMC actuator composed of a thin perfluorinated ionomer membrane with electrodes plated on both surfaces undergoes a large bending motion when a low electric field is applied across its thickness. Such actuators are soft, lightweight, and able to operate in solutions and thus show promise with regard to a wide range of applications, including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. However, the variations induced by changing the type of anion on the device deformation properties are not well understood; therefore, the present study investigated the effects of different anions on the ion exchange process and the deformation behavior of IPMC actuators with palladium electrodes. Ion exchange was carried out in solutions incorporating various anions and the actuator tip displacement in deionized water was subsequently measured while applying a step voltage. In the step voltage response measurements, larger anions such as nitrate or sulfate led to a more pronounced tip displacement compared to that obtained with smaller anions such as hydroxide or chloride. In AC impedance measurements, larger anions generated greater ion conductivity and a larger double-layer capacitance at the cathode. Based on these mechanical and electrochemical measurements, it is concluded that the presence of larger anions in the ion exchange solution induces a greater degree of double-layer capacitance at the cathode and results in enhanced tip deformation of the IPMC actuators.

  20. A finite deformation coupled plastic-damage model for simulating fracture of metal foams

    OpenAIRE

    Pan, Hao; Abu Al-Rub, Rashid

    2014-01-01

    Metal foams are a novel class of lightweight materials with unique mechanical, thermal, and acoustical properties. The low ductility of metal foams hinders the possibilities of applying secondary forming techniques to shape metal foam sandwich panels into desired industrial components. An important factor is the limited studies on their macroscopic damage and fracture behavior under complex loading conditions. There exist numerous mechanistic micromechanics models describing the fracture beha...

  1. Towards efficient modelling of macro and micro tool deformations in sheet metal forming

    NARCIS (Netherlands)

    Lingbeek, R.A.; Meinders, Vincent T.; De Sa, C.; Santos, A.D.

    2007-01-01

    During forming, the deep drawing press and tools undergo large loads, and even though they are extremely sturdy structures, deformations occur. This causes changes in the geometry of the tool surface and the gap width between the tools. The deep drawing process can be very sensitive to these

  2. Watching the growth of bulk grains during recrystallization of deformed metals

    DEFF Research Database (Denmark)

    Schmidt, Søren; Fæster Nielsen, Søren; Gundlach, C.;

    2004-01-01

    We observed the in situ growth of a grain during recrystallization in the bulk of a deformed sample. We used the three-dimensional x-ray diffraction microscope located at the European Synchrotron Radiation Facility in Grenoble, France. The results showed a very heterogeneous growth pattern...

  3. Ideal strength and deformation-induced phase transformation of hcp metals Re, Ru, and Os: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jie, E-mail: wjzamb@gmail.com [Department of Basic Courses, Ordnance Engineering College, Shijiazhuang 050003 (China); Qi Jianying; Zhou Xian [Department of Basic Courses, Ordnance Engineering College, Shijiazhuang 050003 (China)

    2012-02-01

    Highlights: Black-Right-Pointing-Pointer Ideal strengths of hcp metals Re, Ru, and Os were reported for the first time. Black-Right-Pointing-Pointer An hcp {yields} fct {yields} fcc phase transformation was found generally by [112{sup Macron }0] tension. Black-Right-Pointing-Pointer The ideal shear strength is shown to be a good predictor of hardness. Black-Right-Pointing-Pointer Variation in electronic structure accommodates yielding at the critical strain. - Abstract: The intrinsic mechanical properties, deformation-induced transformation, and electronic deformation mechanisms of hexagonal close-packed metals Re, Ru, and Os were systematically studied by density functional theory. The ideal strength, elastic moduli, and toughness parameter were fully presented. Os has the largest ideal strengths and moduli over Re and Ru. Although Re has larger moduli than Ru, its strength is smaller. Thus larger modulus does not mean larger strength. The toughness was predicted to be Re > Ru > Os, reversing brittleness. The ideal shear strength of the easiest slip direction is proposed to qualitatively predict the hardness. A hcp {yields} fct {yields} fcc phase transformation was achieved during [112{sup Macron }0] uniaxial tension. The corresponding energy barriers are 0.29, 0.32, and 0.42 eV/atom for Re, Ru, and Os, respectively. The electronic mechanism underlying yielding was clarified to be bond breaking accompanying disappearance of 'pseudo-gap'. The flow of electron accumulation between charge depletion accommodates the structural transition.

  4. 21 CFR 184.1339 - Guar gum.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Guar gum. 184.1339 Section 184.1339 Food and Drugs... Substances Affirmed as GRAS § 184.1339 Guar gum. (a) Guar gum is the natural substance obtained from the maceration of the seed of the guar plant, Cyamopsis tetragonoloba (Linne) Taub., or Cyamopsis...

  5. 21 CFR 582.7339 - Guar gum.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Guar gum. 582.7339 Section 582.7339 Food and Drugs..., AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7339 Guar gum. (a) Product. Guar gum. (b) Conditions of use. This substance is generally recognized as safe when used...

  6. Oral health benefits of chewing gum

    NARCIS (Netherlands)

    Wessel, Stefan

    2016-01-01

    In the last decades sugar-free chewing gum has developed in an oral healthcare product, next to the conventional products such as the toothbrush and mouthrinses. In this thesis we investigate the oral health benefits of chewing gum and the effects of additives to chewing gum, such as antimicrobials.

  7. Alginate beads of Captopril using galactomannan containing Senna tora gum, guar gum and locust bean gum.

    Science.gov (United States)

    Pawar, Harshal A; Lalitha, K G; Ruckmani, K

    2015-05-01

    Gastro-retentive Captopril loaded alginate beads were prepared by an ionotropic gelation method using sodium alginate in combination with natural gums containing galactomannans (Senna tora seed gum, guar gum and locust bean gum) in the presence of calcium chloride. The process variables such as concentration of sodium alginate/natural polymer, concentration of calcium chloride, curing time, stirring speed and drying condition were optimized. Prepared beads were evaluated for various parameters such as flow property, drug content and entrapment efficiency, size and shape, and swelling index. Surface morphology of the beads was studied using scanning electron microscopy. In vitro mucoadhesion and in vitro drug release studies were carried out on the prepared beads. From the entrapment efficiency and dissolution study, it was concluded that galactomannans in combination with sodium alginate show sustained release property. The bead formulation F4 prepared using combination of sodium alginate and guar gums in the ratio 2:1 showed satisfactory sustained release for 12h. The release of Captopril from the prepared beads was found to be controlled by the swelling of the polymer followed by drug diffusion through the swelled polymer and slow erosion of the beads.

  8. Dependency of deformation twinning on grain orientation in an FCC and a HCP metal

    Institute of Scientific and Technical Information of China (English)

    YANG Ping

    2007-01-01

    Twinning plays important roles in HCP metals and those FCC metals with low stacking fault energy.The structural difierence of two types of metals makes quite different contributions of twinning to plasticity The variety of grain orientation in polycrystalline metals causes the inhomogeneous occurrence of twinning and further distinct transformation kinetics of twinning as strain increases and texture develops.This changes finally the work hardening behavior and mechanical properties.This Paper reveals the dependency of twinning on grain orientation in an FCC TWIP(twinning induced plasticity)steel with high Mn content and in a magnesium alloy using electron-backscatter-difiraction(EBSD) technique,and analyzes the characteristies of twinning in the two types of metals by Schmid factor calculation.In addition,the relation of twinning and shear banding, as well as their influence on properties are discussed.

  9. Achieving large macroscopic compressive plastic deformation and work-hardening-like behavior in a monolithic bulk metallic glass by tailoring stress distribution

    Science.gov (United States)

    Chen, L. Y.; Ge, Q.; Qu, S.; Jiang, Q. K.; Nie, X. P.; Jiang, J. Z.

    2008-05-01

    The limited plastic deformation and lack of work hardening seriously restrict the applications of bulk metallic glasses (BMGs). Here, large macroscopic compressive plastic deformation (over 15%) and work-hardening-like behavior were achieved in a monolithic BMG through tailoring loading stress distribution experimentally. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical condition. It is shown that loading induced stress gradient is responsible for the achievement mentioned above.

  10. Modeling Of Microstructure Evolution Of BCC Metals Subjected To Severe Plastic Deformation

    Science.gov (United States)

    Svyetlichnyy, Dmytro; Majta, Janusz; Muszka, Krzysztof; Łach, Łukasz

    2011-01-01

    Prediction of microstructure evolution and properties of ultrafine-grained materials is one of the most significant, current problems in materials science. Several advanced methods of analysis can be applied for this issue: vertex models, phase field models, Monte Carlo Potts, finite element method (FEM) discrete element method (DEM) and finally cellular automata (CA). The main asset of the CA is ability for a close correlation of the microstructure with the mechanical properties in micro- and meso-scale simulation. Joining CA with the DEM undoubtedly improves accuracy of modeling of coupled phenomena during the innovative forming processes in both micro- and macro-scale. Deformation in micro-scale shows anisotropy, which connected with that the polycrystalline material contains grains with different crystallographic orientation, and grain deformation is depended from configuration of directions of main stresses and axis of grain. Then, CA and DEM must be joint solutions of crystal plasticity theory. In the present model, deformation in macro-scale is transferred to meso-sale, where a block contains several, score or hundreds grains, and then is applied in micro-scale to each grain. Creation of low-angle boundaries and their development into high-angle boundaries are simulated by the cellular automata on the base of calculations using finite element method and crystal plasticity theory. The idea proposed in this study and particular solutions are discussed for the case of ultrafine-grained low-carbon steel.

  11. GumTree: Data reduction

    Science.gov (United States)

    Rayner, Hugh; Hathaway, Paul; Hauser, Nick; Fei, Yang; Franceschini, Ferdi; Lam, Tony

    2006-11-01

    Access to software tools for interactive data reduction, visualisation and analysis during a neutron scattering experiment enables instrument users to make informed decisions regarding the direction and success of their experiment. ANSTO aims to enhance the experiment experience of its facility's users by integrating these data reduction tools with the instrument control interface for immediate feedback. GumTree is a software framework and application designed to support an Integrated Scientific Experimental Environment, for concurrent access to instrument control, data acquisition, visualisation and analysis software. The Data Reduction and Analysis (DRA) module is a component of the GumTree framework that allows users to perform data reduction, correction and basic analysis within GumTree while an experiment is running. It is highly integrated with GumTree, able to pull experiment data and metadata directly from the instrument control and data acquisition components. The DRA itself uses components common to all instruments at the facility, providing a consistent interface. It features familiar ISAW-based 1D and 2D plotting, an OpenGL-based 3D plotter and peak fitting performed by fityk. This paper covers the benefits of integration, the flexibility of the DRA module, ease of use for the interface and audit trail generation.

  12. Plasma Propulsion of a Metallic Micro-droplet and its Deformation upon Laser Impact

    CERN Document Server

    Kurilovich, Dmitry; Torretti, Francesco; Lassise, Adam; Hoekstra, Ronnie; Ubachs, Wim; Gelderblom, Hanneke; Versolato, Oscar O

    2016-01-01

    The propulsion of a liquid indium-tin micro-droplet by nanosecond-pulse laser impact is experimentally investigated. We capture the physics of the droplet propulsion in a scaling law that accurately describes the plasma-imparted momentum transfer, enabling the optimization of the laser-droplet coupling. The subsequent deformation of the droplet is described by an analytical model that accounts for the droplet's propulsion velocity and the liquid properties. Comparing our findings to those from vaporization-accelerated mm-sized water droplets, we demonstrate that the hydrodynamic response of laser-impacted droplets is scalable and independent of the propulsion mechanism.

  13. Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations

    Energy Technology Data Exchange (ETDEWEB)

    Trinkaus, H. [Institut fuer Festkoerperforschung, Forschungszentrum Juelich (Germany); Singh, B.N. [Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Materials Research Dept., Roskilde (Denmark)

    2008-04-15

    Recent in-reactor tensile tests (IRTs) on pure copper have revealed a deformation behaviour which is significantly different from that observed in post-irradiation tensile tests (PITs). In IRTs, the material deforms uniformly and homogeneously without yield drop and plastic instability as commonly observed in PITs. An increase in the pre-yield dose results in an increase in the level of hardening over the whole test periods and a decrease in the uniform elongation suggesting that the materials 'remember' the impact of the pre-yield damage level. These features are modelled in terms of the decoration of dislocations with glissile dislocation loops. During pre-yield irradiation, dislocation decoration is due to the one-dimensional (1D) diffusion of cascade induced self-interstitial (SIA) clusters and their trapping in the stress field of the static grown-in dislocations. During post-yield irradiation and deformation, moving dislocations are decorated by the sweeping of matrix loops. The interaction of dislocations with loops and between loops is discussed as a function of the relevant parameters. On this basis, the kinetics of decoration is treated in terms of fluxes of loops to and reactions with each other in a conceived 2D space of decoration. In this space, loop coalescence, alignment and mutual blocking reactions are characterised by appropriate reaction cross sections. In the kinetic equations for 'dynamic decoration' under deformation, the evolution of the dislocation density is taken into account. Simple solutions of the kinetic equations are discussed. The apparent memory of the system for the pre-yield dose is identified as the result of simultaneous and closely parallel transient evolutions of the cascade damage and the dislocations up to the end of the IRTs. The contributions of dislocation decoration to yield and flow stresses are attributed to the interaction of dislocations with aligned loops temporarily or permanently immobilized

  14. Effect of strain rates on deformation behaviors of an in situ Ti-based metallic glass matrix composite

    Science.gov (United States)

    Jiao, Z. M.; Wang, Z. H.; Chu, M. Y.; Wang, Y. S.; Yang, H. J.; Qiao, J. W.

    2016-06-01

    Quasi-static and dynamic deformation behaviors of an in situ dendrite-reinforced metallic glass matrix composite: Ti56Zr18V10Cu4Be12 were investigated. Upon quasi-static compression, the composite exhibits distinguished work hardening, accompanied by the ultimate strength of 1290 MPa and the plasticity of 20 %. The improved plasticity is attributed to the multiplication of shear bands within the glass matrix and pileups of dislocations within the dendrites. Upon dynamic compression, the stable plastic flow prevails and the yielding stress increases with the strain rate. The macroscopic plasticity decreases considerably, since the shear bands cannot be effectively hindered by dendrites with deteriorated toughness. The dendrite-dominated mechanism results in the positive strain-rate sensitivity, and the Cowper-Symonds model is employed to depict the strain-rate dependency of yielding strength.

  15. Contactless electrical conductivity measurement of metallic submicron-grain material: Application to the study of aluminum with severe plastic deformation.

    Science.gov (United States)

    Mito, M; Matsui, H; Yoshida, T; Anami, T; Tsuruta, K; Deguchi, H; Iwamoto, T; Terada, D; Miyajima, Y; Tsuji, N

    2016-05-01

    We measured the electrical conductivity σ of aluminum specimen consisting of submicron-grains by observing the AC magnetic susceptibility resulting from the eddy current. By using a commercial platform for magnetic measurement, contactless measurement of the relative electrical conductivity σn of a nonmagnetic metal is possible over a wide temperature (T) range. By referring to σ at room temperature, obtained by the four-terminal method, σn(T) was transformed into σ(T). This approach is useful for cylinder specimens, in which the estimation of the radius and/or volume is difficult. An experiment in which aluminum underwent accumulative roll bonding, which is a severe plastic deformation process, validated this method of evaluating σ as a function of the fraction of high-angle grain boundaries.

  16. Analysis of Thermal Buckling of Ceramic-Metal Functionally Graded Plates Using Refined Third Order Shear Deformation Theory

    Directory of Open Access Journals (Sweden)

    S. S. Daimi

    2014-08-01

    Full Text Available Functionally graded materials (FGMs are microscopically inhomogeneous spatial composite materials, typically composed of a ceramic-metal or ceramic-polymer pair of materials. Therefore, it is important to investigate the behaviors of engineering structures such as beams and plates made from FGMs when they are subjected to thermal loads for appropriate design. Therefore, using an improved third order shear deformation theory (TSDT based on more rigorous kinetics of displacements to predict the behaviors of functionally graded plates is expected to be more suitable than using other theories. In this paper, the improved TSDT is used to investigate thermal buckling of functionally graded plates. Temperature dependent material property solutions are adopted to investigate thermal buckling results of functionally graded plates. To obtain the solutions, the Ritz method using polynomial and trigonometric functions for defining admissible displacements and rotations is applied to solve the governing equations.

  17. Bonding Interface and Bending Deformation of Al/316LSS Clad Metal Prepared by Explosive Welding

    Science.gov (United States)

    Guo, Xunzhong; Fan, Minyu; Wang, Liuan; Ma, Fuye

    2016-06-01

    The morphology, elemental distribution, and phase analysis of the bonding interface were investigated by means of SEM, EDS, and XRD to evaluate the interface bonding properties of Al/316LSS clad metal prepared by explosive welding method. Furthermore, the micro-hardness and bending properties were also investigated. The results indicated that the linear and wavy bonding interfaces coexisted and intermetallic phases were present in the local interfacial zone. Moreover, the micro-hardness value at the bonding interface with intermetallic phases was higher than that at the interface without any intermetallic phases. In addition, bulk metal compounds could easily lead to the generation of micro-cracks during the bending forming process.

  18. Atomic-scale simulations of the mechanical deformation of nanocrystalline metals

    DEFF Research Database (Denmark)

    Schiøtz, Jakob; Vegge, Tejs; Di Tolla, Francesco

    1999-01-01

    Nanocrystalline metals, i.e., metals in which the grain size is in the nanometer range, have a range of technologically interesting properties including increased hardness and yield strength. We present atomic-scale simulations of the plastic behavior of nanocrystalline copper. The simulations show...... leads to a hardening as the grain size is increased (reverse Hall-Fetch effect), implying a maximum in hardness for a grain size above the ones studied here. We investigate the effects of varying temperature, strain rate, and porosity, and discuss the relation to recent experiments. At increasing...

  19. Towards high velocity deformation characterisation of metals and composites using Digital Image Correlation

    Directory of Open Access Journals (Sweden)

    Dulieu-Barton J.M.

    2010-06-01

    Full Text Available Characterisation of materials subject to high velocity deformation is necessary as many materials behave differently under such conditions. It is particularly important for accurate numerical simulation of high strain rate events. High velocity servo-hydraulic test machines have enabled material testing in the strain rate regime from 1 – 500 ε/s. The range is much lower than that experienced under ballistic, shock or impact loads, nevertheless it is a useful starting point for the application of optical techniques. The present study examines the possibility of using high speed cameras to capture images and then extracting deformation data using Digital Image Correlation (DIC from tensile testing in the intermediate strain rate regime available with the test machines. Three different materials, aluminium alloy 1050, S235 steel and glass fibre reinforced plastic (GFRP were tested at different nominal strain rates ranging from quasi static to 200 ε/s. In all cases DIC was able to analyse data collected up to fracture and in some cases post fracture. The use of highspeed DIC made it possible to capture phenomena such as multiple necking in the aluminium specimens and post compression failure in GFRP specimens.

  20. Superplastic Deformation and Viscous Flow in an Zr-Based Metallic Glass at 410 Degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Mukai, T.; Nieh, T.G.; Wadsworth, J.; Wang, J.G.

    1998-12-01

    The thermal properties of an amorphous alloy (composition in at.%: Zr-l0Al-5Ti-l7.9Cu-14.6Ni), and particularly the glass transition and crystallization temperature as a function of heating rate, were characterized using Differential Scanning Calorimetry (DSC). X-ray diffraction analyses and Transmission Electron Microscopy were also conducted on samples heat-treated at different temperatures for comparison with the DSC results. Superplasticity in the alloy was studied at 410 degrees C, a temperature within the supercooled liquid region. Both single strain rate and strain rate cycling tests in tension were carried out to investigate the deformation behavior of the alloy in the supercooled liquid region. The experimental results indicated that the alloy did not behave like a Newtonian fluid.

  1. Deformation-strengthening during rolling Cu60Zr20Ti20 bulk metallic glass

    DEFF Research Database (Denmark)

    Cao, Q.P.; Li, J.F.; Hu, Yuyan

    2007-01-01

    Mechanical strength evolutions during rolling the Cu60Zr20Ti20 bulk metallic glass (BMG) at room temperature (RT) and cryogenic temperature (CT) have been investigated by measuring the microhardness. The hardness slightly increases during the initial rolling stage as a result of the gradually......-rolling. It is proposed that phase separation may be a more effective way to strengthen the BMG than the incorporation of the nanocrystallites with crystal defects....

  2. Gum copal and gum damar: Novel matrix forming materials for sustained drug delivery

    OpenAIRE

    Morkhade D; Fulzele S; Satturwar P; Joshi S

    2006-01-01

    This study concerns the evaluation of natural gum copal and gum damar as novel sustained release matrix forming materials in tablet formulation. Along with the physicochemical properties, gum copal and gum damar were characterized for molecular weight, polydispersity index and glass transition temperature. Matrix tablets were prepared by wet granulation technique using isopropyl alcohol as a granulating agent. Diclofenac sodium was used as a model drug. Tablet weight (250 mg) and diameter (9 ...

  3. Deformation and fracture properties of metals with non-metallic inclusions; Verformung und Bruch von Metallen mit nichtmetallischen Einschluessen

    Energy Technology Data Exchange (ETDEWEB)

    Schmauder, S.; Soppa, E. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt

    1998-12-31

    Microstructural effects due to formation of non-uniform lines of non-metallic inclusions in the matrix are examined with respect to their macro-, meso-, and micromechanical effects in the alloy Al(6061) reinforced by SiC inclusions. A comparative analysis of results obtained with various microstructures reveals essential differences in the formation of shear bands, stress peaks, and strain concentrations in the material structure. The maxima and the distribution of those field variables are determined not only by the arrangement of inclusions clusters in the stringers but also depend on the presence and number of single-particle inclusions in pure matrix material. The banding of the microstructure causes a strongly anisotropic behaviour in terms of stress and strain distributions. (orig./CB) [Deutsch] In diesem Beitrag werden Gefuegeeinfluesse aufgrund unterschiedlich starker zeiliger Anordnungen der Teilchen in der Matrix im Hinblick auf ihre makro-, meso- und mikromechanischen Auswirkungen am Beispiel einer SiC-teilchenverstaerkten Aluminiumlegierung Al(6061) untersucht. Ein Vergleich der Ergebnisse verschiedener Gefuege zeigt wesentliche Unterschiede hinsichtlich der Ausbildung von Scherbaendern, Spannungsspitzen und von Dehnungskonzentrationen im Werkstoffgefuege. Die Maxima und die Verteilung dieser Feldgroessen sind nicht nur abhaengig davon, wie die Teilchen in den Zeilen angeordnet sind, sondern auch davon, ob einzelne Teilchen in reinen Matrixbereichen vorhanden sind. Die Zeiligkeit des Gefueges fuehrt zu einem stark anisotropen Verhalten hinsichtlich Spannungs- und Dehnungsverteilungen. (orig.)

  4. Caffeine gum minimizes sleep inertia.

    Science.gov (United States)

    Newman, Rachel A; Kamimori, Gary H; Wesensten, Nancy J; Picchioni, Dante; Balkin, Thomas J

    2013-02-01

    Naps are an effective strategy for maintaining alertness and cognitive performance; however, upon abrupt wakening from naps, sleep inertia (temporary performance degradation) may ensue. In the present study, attenuation of post-nap sleep inertia was attempted by administration of caffeine gum. Using a double-blind, placebo-controlled crossover design, 15 healthy, non-smoking adults were awakened at 1 hr. and again at 6 hr. after lights out (0100 and 0600, respectively) and were immediately administered a gum pellet containing 100 mg of caffeine or placebo. A 5-min. psychomotor vigilance task was administered at 0 min., 6 min., 12 min., and 18 min. post-awakening. At 0100, response speed with caffeine was significantly better at 12 min. and 18 min. post-awakening compared to placebo; at 0600, caffeine's effects were evident at 18 min. post-awakening. Caffeinated gum is a viable means of rapidly attenuating sleep inertia, suggesting that the adenosine receptor system is involved in sleep maintenance.

  5. Modeling deformation behavior of Cu-Zr-Al bulk metallic glass matrix composites

    Science.gov (United States)

    Pauly, S.; Liu, G.; Wang, G.; Das, J.; Kim, K. B.; Kühn, U.; Kim, D. H.; Eckert, J.

    2009-09-01

    In the present work we prepared an in situ Cu47.5Zr47.5Al5 bulk metallic glass matrix composite derived from the shape memory alloy CuZr. We use a strength model, which considers percolation and a three-microstructural-element body approach, to understand the effect of the crystalline phase on the yield stress and the fracture strain under compressive loading, respectively. The intrinsic work-hardenability due to the martensitic transformation of the crystalline phase causes significant work hardening also of the composite material.

  6. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  7. The External Periodic Influence Effect on the Kinetics of Metals Fragmentationduring the Severe Plastic Deformation

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2015-03-01

    Full Text Available Using the Landau theory of phase transitions, the solids fragmentation during the process of severe plastic deformation is studied. The density of grain boundaries, dislocations and entropy are introduced for describing the defect structures appearing. This allows us to take into account the two channels of energy dissipation (thermal one and defects formation. The phase diagram that establishes the domains of realization of different limiting structures types is obtained. The interaction of several defect types on the formation of limiting structure in terms of internal energy is studied. The formation conditions for two limiting structures are found. They correspond to the mode, in which there is a mixture of different grain sizes. The kinetics of setting in the steady-state values of the defects density is investigated within the scope of the adiabatic approximation, at which the dislocations density change follows the evolution of the grain boundaries density. The external periodic influence is also analyzed. It is shown that frequency and amplitude of external influence change the system behavior.

  8. Study on Deformation of Miniature Metal Bellows in Cryocooler Following Temperature Change of Internal Gas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Ha [LIGNex1 Co. Ltd., Gumi (Korea, Republic of); Lee, Tae Won [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2015-04-15

    A bellows is an important temperature control component in a Joule-Thomson micro-cryocooler. It is designed using a very thin shell, and the inside of the bellows is filled with nitrogen gas. The bellows is made of a nickel-cobalt alloy that maintains its strength and elastic properties in a wide range of temperatures from cryogenic to 300℃. The pressure of the gas and the volume within the bellows vary according to the temperature of the gas. As a result, the bellows contracts or expands in the axial direction like a spring. To explore this phenomenon, the deformation of the bellows and its internal volume must be calculated iteratively under a modified pressure until the state equation of the gas is satisfied at a given temperature. In this paper, the modified Benedict-Webb-Rubin state equation is adopted to describe the temperature-volume-pressure relations of the gas. Experiments were performed to validate the proposed method. The results of a numerical analysis and the experiments showed good agreement.

  9. Gum copal and gum damar: Novel matrix forming materials for sustained drug delivery

    Directory of Open Access Journals (Sweden)

    Morkhade D

    2006-01-01

    Full Text Available This study concerns the evaluation of natural gum copal and gum damar as novel sustained release matrix forming materials in tablet formulation. Along with the physicochemical properties, gum copal and gum damar were characterized for molecular weight, polydispersity index and glass transition temperature. Matrix tablets were prepared by wet granulation technique using isopropyl alcohol as a granulating agent. Diclofenac sodium was used as a model drug. Tablet weight (250 mg and diameter (9 mm was kept constant. Tablets were evaluated for pharmacotechnical properties, drug content uniformity and in vitro drug release kinetics. Effect of gum concentration (10, 20 and 30% w/w with respect to total tablet weight on in vitro drug release profile was examined. Both the gums produced matrix tablets with good strength and acceptable pharmacotechnical properties. Matrix tablets with 30% w/w gum copal and gum damar showed sustained drug delivery beyond 10 h. Drug release from gum copal matrix tablets followed zero order kinetics while gum damar (10 and 20% w/w was found suitable to formulate the insoluble plastic matrix that releases the drug by diffusion. It is concluded that both gums possess substantial matrix forming property that could be used for sustained drug delivery.

  10. First-principles study of elastic mechanical responses to applied deformation of metal-organic frameworks

    Science.gov (United States)

    Banlusan, Kiettipong; Strachan, Alejandro

    2017-05-01

    We use density functional theory to compute the elastic constant tensors of two families of metal-organic frameworks (MOFs) to establish relationships between their structures and mechanical properties. The Zn family consist of Zn4O centers each coordinated by six organic linkers along the ⟨100⟩ directions; we studied three linkers of increasing lengths: 1,4-benzenedicarboxylate (BDC), 4,4'-biphenyl-dicarboxylate (BPDC), and 4,4''-terphenyl-dicarboxylate. This relatively weak connectivity leads to high anisotropy; in fact, Zn-MOFs exhibit extremely low shear modulus and are near a mechanical instability. In contrast, Zr family studied consists of Zr6O4(OH)4 centers each linked by fumarate, BDC, and BPDC ligands along the twelve ⟨110⟩ directions. The higher structural connectivity results in stiffer frameworks with lower anisotropy. The smallest Zr-MOF exhibits nearly isotropic elasticity with a Zener ratio of 1.06. The stiffest and most compliant directions of both families are directly related to the orientation of the organic linkers. Temperature has a significant effect on elastic moduli; for example, we observed reduction of average Young's modulus and shear modulus by about 30% from 0 K to 300 K in Zn-BPDC even when it exhibits large negative thermal expansion. We find the effect of temperature to be directionally dependent, leading to an increase in anisotropy upon increasing temperature. The predicted effects of temperature and anisotropy help reconcile a longstanding discrepancy between experiments and first principles calculations.

  11. Modelling plastic deformation in BCC metals: Dynamic recovery and cell formation effects

    Energy Technology Data Exchange (ETDEWEB)

    Galindo-Nava, E.I. [Department of Materials Science and Metallurgy, Pembroke Street, CB2 3QZ, University of Cambridge, Cambridge (United Kingdom); Department of Materials Science and Engineering, Mekelweg 2 2628 CD, Delft University of Technology, Delft (Netherlands); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [Department of Materials Science and Metallurgy, Pembroke Street, CB2 3QZ, University of Cambridge, Cambridge (United Kingdom)

    2012-12-15

    A recently developed model for describing plasticity in FCC metals (E.I., Galindo-Nava, P.E.J., Rivera-Diaz-del-Castillo, Mater. Sci. Eng. A 543 (2012) 110-116; E.I. Galindo-Nava, P.E.J. Rivera-Diaz-del-Castillo, Acta Mater. 60 (2012) 4370-4378) has now been applied to BCC. The core of the theory is the thermostatistical description of dislocation annihilation paths, which determines the dynamic recovery rate of the material. Input to this is the energy for the formation, migration and ordering of dislocation paths; the latter term corresponds to the statistical entropy which features strongly on the solution. The distinctions between FCC and BCC stem primarily from the possible directions and planes for dislocation slip and cross-slip, as well as from the presence of the kink-pair mechanism for dislocation migration in BCC, which are incorporated to the mathematical formulation of the model. The theory is unique in describing the stress-strain response for pure iron, molybdenum, tantalum, vanadium and tungsten employing physical parameters as input; the description is made for wide ranges of temperature and strain rate. Additionally, succinct equations to predict dislocation cell size variation with strain, strain rate and temperature are provided and validated for pure iron.

  12. Analysis of localized shear deformation of ductile metal based on gradient-dependent plasticity

    Institute of Scientific and Technical Information of China (English)

    王学滨; 代树红; 海龙; 潘一山

    2003-01-01

    Shear localization in linear strain softening heterogeneous material under simple shear was investigated analytically.The closed-form solutions obtained based on gradient plasticity theory considering interactions and interplaying among microstructures due to heterogeneity of metal material show that in the normal direction of shear band,elastic shear displacement is linear; while plastic and total shear displacement are non-linear.Elastic shear strain in the band is uniform and the non-uniformity of total shear displacement stems from localized plastic shear displacement.In the center of the band,plastic and total shear displacement all reach their maximum values.In strain-softening process,elastic displacement decreases as flow shear stress decreases.Contrarily,plastic and total shear displacement increase and manifest shear localization occurs progressively.Under the same shear stress level,plastic and total shear displacement increase as strain softening modulus and elastic shear modulus decrease.The present analytical solutions were compared with many experimental results and the agreement is good.

  13. Local melting to design strong and plastically deformable bulk metallic glass composites

    Science.gov (United States)

    Qin, Yue-Sheng; Han, Xiao-Liang; Song, Kai-Kai; Tian, Yu-Hao; Peng, Chuan-Xiao; Wang, Li; Sun, Bao-An; Wang, Gang; Kaban, Ivan; Eckert, Jürgen

    2017-02-01

    Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties. Through adjusting local melting process parameters (i.e. input powers, local melting positions, and distances between the electrode and amorphous plate), the size, volume fraction, and distribution of B2 crystals were well tailored and the corresponding formation mechanism was clearly clarified. The resultant BMG composites exhibit large compressive plasticity and high strength together with obvious work-hardening ability. This compelling approach could be of great significance for the steady development of metastable CuZr-based alloys with excellent mechanical properties.

  14. Effect of Chord Splice Joints on Force Distribution and Deformations in Trusses with Punched Metal Plate Fasteners

    DEFF Research Database (Denmark)

    Ellegaard, Peter

    2007-01-01

    The span of roof trusses with punched metal plate fasteners (nail plates) makes it often necessary to use splice joints in the top and bottom chords. In the finite element models used for design of the trusses these splice joints are normally assumed to be either rotationally stiff or pinned - th...... of splice joints on section forces and displacements are discussed considering the results from finite element calculations for a fink truss. It seems that the guidelines for treating splice joints as rotationally stiff do not necessarily lead to more realistic truss models....... - their real behaviour is semi-rigid. The influence of splice joints on the distribution of member forces and rotations in the splice joints is investigated in this paper. A finite element program, TrussLab, where the splice joints are given semi-rigid properties is used to analyse the effect of splice joints...... if their deformation has no significant effect upon the distribution of member forces according to Eurocode 5. Two simple guidelines for the design and location of splice joints are given in Eurocode 5 for treating the splice joints as rotationally stiff. The reasonability of these guidelines and the influence...

  15. Gum chewing affects academic performance in adolescents

    Science.gov (United States)

    Chewing gum may have an impact on improved memory during specific tasks of recognition and sustained attention. Research objective was to determine the effect of gum chewing on standardized test scores and math class grades of eighth grade students. Four math classes, 108 students, were randomized i...

  16. 21 CFR 172.695 - Xanthan gum.

    Science.gov (United States)

    2010-04-01

    ... recovery with isopropyl alcohol. It contains D-glucose, D-mannose, and D-glucuronic acid as the dominant... specifications: (1) Residual isopropyl alcohol not to exceed 750 parts per million. (2) An aqueous solution... Gum Gel Test Blend on a weighing paper or in a weighing pan 1.0 gram of powdered locust bean gum...

  17. 21 CFR 573.1010 - Xanthan gum.

    Science.gov (United States)

    2010-04-01

    ... agent, or bodying agent in animal feed as follows: (1) In calf milk replacers at a maximum use level of..., FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive Listing § 573.1010 Xanthan gum. The food additive xanthan gum may be safely used in animal feed as...

  18. Guar gum, xanthan gum, and HPMC can define release mechanisms and sustain release of propranolol hydrochloride.

    Science.gov (United States)

    Mughal, Muhammad Akhlaq; Iqbal, Zafar; Neau, Steven Henry

    2011-03-01

    The objectives were to characterize propranolol hydrochloride-loaded matrix tablets using guar gum, xanthan gum, and hydroxypropylmethylcellulose (HPMC) as rate-retarding polymers. Tablets were prepared by wet granulation using these polymers alone and in combination, and physical properties of the granules and tablets were studied. Drug release was evaluated in simulated gastric and intestinal media. Rugged tablets with appropriate physical properties were obtained. Empirical and semi-empirical models were fit to release data to elucidate release mechanisms. Guar gum alone was unable to control drug release until a 1:3 drug/gum ratio, where the release pattern matched a Higuchi profile. Matrix tablets incorporating HPMC provided near zero-order release over 12 h and erosion was a contributing mechanism. Combinations of HPMC with guar or xanthan gum resulted in a Higuchi release profile, revealing the dominance of the high viscosity gel formed by HPMC. As the single rate-retarding polymer, xanthan gum retarded release over 24 h and the Higuchi model best fit the data. When mixed with guar gum, at 10% or 20% xanthan levels, xanthan gum was unable to control release. However, tablets containing 30% guar gum and 30% xanthan gum behaved as if xanthan gum was the sole rate-retarding gum and drug was released by Fickian diffusion. Release profiles from certain tablets match 12-h literature profiles and the 24-h profile of Inderal(®) LA. The results confirm that guar gum, xanthan gum, and HPMC can be used for the successful preparation of sustained release oral propranolol hydrochoride tablets.

  19. Effect of height to diameter ($h/d$) ratio on the deformation behaviour of Fe–Al$_2$O$_3$ metal matrix nanocomposites

    Indian Academy of Sciences (India)

    PALLAV GUPTA; DEVENDRA KUMAR; A K JHA; OM PARKASH

    2016-09-01

    The present paper reports the effect of height to diameter ($h/d$) ratio on the deformation behaviour of Fe–Al$_2$O$_3$ metal matrix nanocomposites (MMNCs) during bulk processing. Sintered compacts were machined to the required size with different $h/d$ ratios. Test specimens were subjected to deformation at room temperature under three different interfacial friction conditions such as dry, solid and liquid lubrications. Deformed specimensshow a significant improvement in the density and hardness. Results also revealed the formation of a nanosize iron aluminate phase due to reactive sintering, which in turn contributes to grain refinement. Experimental density of the specimens was also verified with the theoretical density using the standard equations. It is expected that the present work will be useful in designing and developing MMNC products with better quality at competitive cost.

  20. Assessment of larval deformities and selenium accumulation in northern pike (Esox lucius) and white sucker (Catostomus commersoni) exposed to metal mining effluent.

    Science.gov (United States)

    Muscatello, Jorgelina R; Janz, David M

    2009-03-01

    Uranium mining and milling operations in northern Saskatchewan (Canada) release effluents with elevated levels of certain trace metals and metalloids, including selenium. The goal of the present study was to evaluate the presence of selenium-induced deformities in northern pike (Esox lucius) and white sucker (Catostomus commersoni) larvae originating from adults collected downstream of a uranium mine. Eggs were fertilized in the field and incubated in the laboratory following a two-way (crossover) analysis-of-variance experimental design to discriminate effects from maternal transfer versus those from exposure to site water in the developing embryos. Selenium concentrations in northern pike and white sucker eggs (8.02 and 4.89 microg/g dry wt, respectively; mean +/- standard error throughout) from the exposure site were approximately two- to threefold higher than reference (2.35 +/- 0.20 and 1.94 +/- 0.25 microg/g dry wt, respectively). Among all evaluated deformities (skeletal curvatures, craniofacial deformities, fin deformities, and edema), only edema in white sucker fry from the exposure site was slightly elevated ( approximately 3%) compared to reference. The occurrence of edema, however, can be associated with factors other than selenium (e.g., other metals and organic compounds). Both fish species displayed strong linear relationships between the selenium concentrations in eggs and other tissues (muscle, liver, kidney, and bone), suggesting that selenium concentrations in eggs could be predicted from selenium concentrations in adult tissues. The lack of a clear, toxic response in the present study is in agreement with selenium thresholds for early life-stage deformities reported in other studies, with egg selenium concentrations in northern pike and white sucker collected at the exposure site being less than the 10 microg/g (dry wt) threshold associated with the presence of deformities.

  1. GUAR GUM: PRESENT STATUS AND APPLICATIONS

    Directory of Open Access Journals (Sweden)

    Surendra Tripathy

    2013-08-01

    Full Text Available Naturally occurring excipients are currently getting prime importance among which the polysaccharides occupy a special position because of their easy availability, non-toxic, eco-friendly and biodegradable nature. The objective of this review was to explore the excipient profile of Guar gum which is obtained from Cyamopsis tetragonolobus (Linn. Leguminosae. The chief constituent of guar gum is a Gallactomannan which is composed of galactose and mannose in a ratio of 1:2 that provides the main physical phenomenon of gelling or thickening to this gum. The chemistry of this gallactomannan suggested the presence of multiple hydroxyl groups which are proved to be excellent for derivatization by grafting or cross-linking with other polymers to create new chemically modified entity of desired properties. The native as well as guar gum derivatives are found to have therapeutic importance in certain physiological disorders. Guar gum is used as suspending, emulsifying and stabilizing agent in the conventional dosage forms. In tablet dosage form it is used as a potential binding and disintegrating agent. The swelling property of guar gum is used for controlling the drug release rate in the novel pharmaceutical dosage forms. By virtue of its better thickening and stabilizing power accompanied by a sound safety profile, guar gum has acquired a wide acceptance in cosmetics and food industry.

  2. Interstellar gas in the Gum Nebula

    Science.gov (United States)

    Wallerstein, G.; Jenkins, E. B.; Silk, J.

    1980-01-01

    A survey of the interstellar gas near the Gum Nebula by optical observation of 67 stars at Ca II, 42 stars at Na I, and 14 stars in the UV with the Copernicus satellite provided radial velocities and column densities for all resolved absorption components. Velocity dispersions for gas in the Gum Nebula are not significantly larger than in the general interstellar medium; the ionization structure is predominantly that of an H II region with moderately high ionization. Denser, more highly ionized clouds are concentrated toward the Gum Nebula; these clouds do not show the anomalously high ionization observed in the Vela remnant clouds.

  3. Deformable Nanolaminate Optics

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K

    2006-05-12

    We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.

  4. Modification of hydroxypropyl guar gum with ethanolamine.

    Science.gov (United States)

    Zhao, Yongchao; He, Jianping; Han, Xiaoxiao; Tian, Xiulin; Deng, Mingyu; Chen, Weiping; Jiang, Bo

    2012-10-01

    A new guar gum derivative containing amino group was synthesized through nucleophilic substitution of p-toluenesulfonate activated hydroxypropyl guar gum with ethanolamine. For the preparation of p-toluenesulfonate esters hydroxypropyl guar gum, the results showed that the reaction rate was optimal at 25 °C and the reaction could reach equilibrium state when it was carried out for 10h at 25 °C. For the nucleophilic substitution of tosyl group with ethanolamine, the reaction was completed after 10h reaction at 50 °C. The structures of products were characterized by NMR and FT-IR spectroscopy. The results showed that the p-toluenesulfonate esters can be effectively substituted by ethanolamine to form the hydroxyethyl amino hydroxypropyl guar gum (EAHPG). The content of nitrogen of EAHPG was determined by acid-base titration and element analysis.

  5. Gum Disease - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... Chinese - Traditional) PDF California Dental Association Receding Gums English 牙齦退縮 - 繁體中文 (Chinese - Traditional) PDF California Dental Association French (français) Gingivitis Gingivite - français (French) Bilingual PDF Health ...

  6. Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

    Science.gov (United States)

    Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

    2015-01-01

    Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

  7. Evaluation of microscopic deformation behaviors of metal matrix composite by means of SFC test and acoustic emission (Part I :Effect of loading direction)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun; Kang, Moon Phil [Pusan National University, Pusan (Korea, Republic of)

    1998-11-15

    Metal matrix composites(MMCs) offer significant increase in elastic modulus and strength as well as improve resistance to fatigue initiation, creep and wear. For the successful application of MMC to structure, it is very important to understand micro-failure mechanism of material. However, due to complex deformation behavior intrinsically of bulk composite panel, single fiber composite(SFC) has been successfully used to understand a fundamental mechanism of deformation in MMC. The substantial failure mechanisms of MMC were affected by many factors such as the loading direction, the heat treatment condition, matrix properties and volume fraction. In this study, the microscopic deformation behavior of MMC is investigated for single SiC fiber reinforced aluminium alloy under the different loading direction, that is, longitudinal and transverse loading. Acoustic emission(AE) technique has been also used to detect the signals corresponding to each microscopic deformation behavior under the loading. Special attention is given to AE characteristics associated with interfacial debonding between fiber and matrix under the different leading direction.

  8. Synthesis of Novel Nanocomposites of Silica and Guar Gum:Efficient Zinc Ion Binder

    Institute of Scientific and Technical Information of China (English)

    Vandana; Singh; Sadanand; Pandey; Somit; kumar; Singh; Rashmi; Sanghi

    2007-01-01

    1 Results Adsorption using commercial activated carbon (CAC)[1] can remove heavy metals from wastewater[2-4].However,CAC remains an expensive material for heavy metal removal.Ion exchange techniques are also used but it generates volumetric sludge and increases the cost[5].Using naturally occurring seed polysaccharides can solve these problems but their solubility in water limits its application as an adsorbent.Guar gum is a commercially available,industrially important[6-7] polysaccharide material havi...

  9. Colon targeted curcumin delivery using guar gum.

    Science.gov (United States)

    Elias, Edwin J; Anil, Singhal; Ahmad, Showkat; Daud, Anwar

    2010-06-01

    Curcumin is used in the treatment of colon cancer, but its very poor absorption in the upper part of the GIT is a major concern. As a site for drug delivery, the colon offers a near neutral pH, reduced digestive enzymatic activity, a long transit time and an increased responsiveness to absorption enhancers. The aim of the present study was to identify a suitable polymer (guar gum) based matrix tablet for curcumin with sufficient mechanical strength and promising in vitro mouth-to-colon release profile. Three formulations of curcumin were prepared using varying concentrations of guar gum containing 50 mg curcumin by the wet granulation method. Tablets were subjected to evaluation by studying parameter like hardness, friability, drug content uniformity, and in-vitro drug release. In vitro drug release was evaluated using simulated stomach, intestinal and colonic fluids. The susceptibility of guar gum to colonic bacteria was also assessed by a drug release study with rat caecal contents. The 40% guar gum containing formulation (F-1) showed better drug release (91.1%) after 24 hours in the presence of rat caecal contents in comparison with the 50% guar gum containing formulation (F-2) (82.1%). Curcumin could, thus, be positively delivered to the colon for effective colon cancer treatment using guar gum.

  10. Effect of Hafnium and Zirconium to Glass Forming Ability, Thermal Stability, Plasticity Deformation and Crystallization of Ni-Free Pentabasic Ti-Based Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Oak J.J.

    2017-06-01

    Full Text Available The newly designed Ti-based bulk metallic glass (BMG in which case of fracture behavior was observed 1990MPa to compressive strength with a wide plastic deformation around 7% after process of elastic deformation. This phenomenon can be compared with those of Ti-based alloys and other Ti-based BMGs and indicates high potential to be applied in use. It was evaluated the Ti-based BMG for thermal stability that the reduced glass parameters, ΔTx, Trg and γ, are 79K, 0.50 and 0.38, respectively. In addition, it reveals high activation energies for crystallization in which are estimated to Ex1 = 291.77 ±9.71 kJ/mol, Ex2 = 588.77 ±28.88 kJ/mol and Ex3 = 330.26 ±3.61 kJ/mol on kissinger plotting in this study.

  11. Hydrolytic fragmentation of seed gums under microwave irradiation.

    Science.gov (United States)

    Singh, V; Tiwari, A

    2009-03-01

    The seed gum solutions of Ipomoea purga, Ipomoea palmata, Ipomoea dasysperma, Cyanaposis tetragonolobus (Guar gum) and Crotolaria medicaginea were microwave (MW) irradiated and their degradation to oligo and monosaccharides was investigated. The gum solutions were fragmented into oligosaccharides/constituent monosaccharides depending upon the length of MW exposure in presence of catalytic amount of mineral acid or even when no acid was used. A mechanism for the microwave induced hydrolytic degradation of the seed gums has been proposed. The MW exposure time required for the partial and complete degradation of the gums was found dependent on the types of the linkages and degree of the branching present in the gums.

  12. Fractionation of Mastic Gum in Relation to Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    Mohammad Sharif Sharifi

    2009-04-01

    Full Text Available Mastic gum is a viscous light-green liquid obtained from the bark of Pistacia lentiscus var. chia. which belongs to the Anacardiaceae family. The gum has been fractionated to investigate the antimicrobial activity of the whole gum and its fractions against various strains of Helicobacter pylori. The polymeric gum fraction was separated from the essential oil and the resin (trunk exudates without essential oil to assess and compare the anti-H. pylori activity of the polymer fraction against lower molecular weight fractions, the gum itself and masticated gum. The polymer fraction was also oxidized and assessed for antimicrobial activity.

  13. Design and Fabrication of a Large-Stroke Deformable Mirror Using a Gear-Shape Ionic-Conductive Polymer Metal Composite

    Directory of Open Access Journals (Sweden)

    Guo-Dung John Su

    2012-08-01

    Full Text Available Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young’s modulus and Poisson’s ratio. We divided an ion exchange polymer, also known as Nafion®, into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

  14. A Comparative Study of the Inhibitory Effect of Gum Exudates from Khaya senegalensis and Albizia ferruginea on the Corrosion of Mild Steel in Hydrochloric Acid Medium

    Directory of Open Access Journals (Sweden)

    Paul Ocheje Ameh

    2015-01-01

    Full Text Available A comparative study of the inhibitory potentials of gum exudates from Albizia ferruginea (AF and Khaya senegalensis (KS on the corrosion of mild steel in HCl medium was investigated using weight loss and gasometric method. The active chemical constituents of the gum were elucidated using GC-MS while FTIR was used to identify the bonds/functional groups in the gums. The two gum exudates were found to be good corrosion inhibitors for mild steel in acidic medium. On comparison, maximum inhibition efficiency was found in Khaya senegalensis with 82.56% inhibition efficiency at 0.5% g/L concentration of the gum. This may be due to the fact that more compounds with heteroatoms were identified in the GCMS spectrum of KS gum compared to the AF gum. The presence of such compounds may have enhanced their adsorption on the metal surface and thereby blocking the surface and protecting the metal from corrosion. The adsorption of the inhibitors was found to be exothermic and spontaneous and fitted the Langmuir adsorption model.

  15. Paramagnetic susceptibility of the Zr62Cu22Al10Fe5Dy1 metallic glass subjected to high-pressure torsion deformation

    Science.gov (United States)

    Korolev, A. V.; Kourov, N. I.; Pushin, V. G.; Gunderov, D. V.; Boltynjuk, E. V.; Ubyivovk, E. V.; Valiev, R. Z.

    2017-09-01

    The Zr62Cu22Al10Fe5Dy1 bulk metallic glass is studied in the as-cast state and in the state after processing by high-pressure torsion at temperatures of 20 °C and 150 °C. According to the data from X-ray diffraction and transmission electron microscopy, the structural state of the samples depends weakly on the conducted processing. At the same time, magnetic measurements reveal well recordable changes in paramagnetic susceptibility induced by the processing of the samples. It is assumed that, because of high-pressure torsion deformation, there occurs a noticeable change in the material electronic structure, which leads to a change in the full susceptibility of the samples. The performed studies demonstrate that paramagnetic susceptibility may be an indicator of a change in the structural state of paramagnetic amorphous metallic substances.

  16. Design, formulation and evaluation of nicotine chewing gum

    Directory of Open Access Journals (Sweden)

    Abolfazl Aslani

    2012-01-01

    Conclusion: Taste enhancement of nicotine gums was achieved where formulations comprised aspartame as the sweetener and cherry and eucalyptus as the flavoring agents. Nicotine gums of pleasant taste may, therefore, be used as NRT to assist smokers quit smoking.

  17. More Evidence Ties Gum Health to Stroke Risk

    Science.gov (United States)

    ... 163755.html More Evidence Ties Gum Health to Stroke Risk Study shows increasing risk of brain blockage ... as people with healthy gums to suffer a stroke, new research suggests. It's not the first study ...

  18. Could a Germ Link Gum Disease, Rheumatoid Arthritis?

    Science.gov (United States)

    ... 162571.html Could a Germ Link Gum Disease, Rheumatoid Arthritis? Study may offer new insight into the cause ... the long-noticed connection between gum disease and rheumatoid arthritis, a new study suggests. The discovery might also ...

  19. E-Cigarettes Not Good to Gums, Study Finds

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162118.html E-Cigarettes Not Good to Gums, Study Finds Nicotine, ... in New York exposed nonsmokers' gum tissue to e-cigarette vapors. Their findings appear to counter arguments ...

  20. Investigation of Elastic Deformation Mechanism in As-Cast and Annealed Eutectic and Hypoeutectic Zr–Cu–Al Metallic Glasses by Multiscale Strain Analysis

    Directory of Open Access Journals (Sweden)

    Hiroshi Suzuki

    2016-01-01

    Full Text Available Elastic deformation behaviors of as-cast and annealed eutectic and hypoeutectic Zr–Cu–Al bulk metallic glasses (BMG were investigated on a basis of different strain-scales, determined by X-ray scattering and the strain gauge. The microscopic strains determined by Direct-space method and Reciprocal-space method were compared with the macroscopic strain measured by the strain gauge, and the difference in the deformation mechanism between eutectic and hypoeutectic Zr–Cu–Al BMGs was investigated by their correlation. The eutectic Zr50Cu40Al10 BMG obtains more homogeneous microstructure by free-volume annihilation after annealing, improving a resistance to deformation but degrading ductility because of a decrease in the volume fraction of weakly-bonded regions with relatively high mobility. On the other hand, the as-cast hypoeutectic Zr60Cu30Al10 BMG originally has homogeneous microstructure but loses its structural and elastic homogeneities because of nanocluster formation after annealing. Such structural changes by annealing might develop unique mechanical properties showing no degradations of ductility and toughness for the structural-relaxed hypoeutectic Zr60Cu30Al10 BMGs.

  1. Viscoelastic properties of aqueous guar gum derivative solutions under large amplitude oscillatory shear (LAOS).

    Science.gov (United States)

    Szopinski, Daniel; Luinstra, Gerrit A

    2016-11-20

    The industrial relevant nonlinear viscoelastic properties of aqueous carboxymethyl hydroxypropyl guar gum (CMHPG) and non-ionic hydroxypropyl guar gum (HPG) solutions between semi-dilute and concentrated solution state were investigated by large amplitude oscillatory shear flow (LAOS). Aqueous CMHPG and HPG solutions enter the nonlinear flow regime at deformations γ0>100%. The nonlinear stress waveforms were analyzed by FT-rheology and orthogonal stress decomposition along the MITlaos framework. A rheological fingerprint is generated (Pipkin space) showing that the guar gum derivative solutions undergo a shear-thinning at high strains, which is preceded by a thickening above a minimum strain rate at intermediate strains. The influence and breakup of superstructures/aggregates gives a "rheological fingerprint", a function of the applied deformation and time scale (Pipkin space). A characteristic process time was found that scales exponentially with the overlap parameter with an exponent of 4/2, and is proposed to represent the relaxation process of the superstructure in solution.

  2. Quantification and Qualification of Bacteria Trapped in Chewed Gum

    OpenAIRE

    Wessel, Stefan W.; van der Mei, Henny C.; David Morando; Slomp, Anje M.; Betsy van de Belt-Gritter; Amarnath Maitra; Busscher, Henk J.

    2015-01-01

    Chewing of gum contributes to the maintenance of oral health. Many oral diseases, including caries and periodontal disease, are caused by bacteria. However, it is unknown whether chewing of gum can remove bacteria from the oral cavity. Here, we hypothesize that chewing of gum can trap bacteria and remove them from the oral cavity. To test this hypothesis, we developed two methods to quantify numbers of bacteria trapped in chewed gum. In the first method, known numbers of bacteria were finger-...

  3. Bond deformation paths and electronic instabilities of ultraincompressible transition metal diborides: Case study of OsB2 and IrB2

    Science.gov (United States)

    Zhang, R. F.; Legut, D.; Wen, X. D.; Veprek, S.; Rajan, K.; Lookman, T.; Mao, H. K.; Zhao, Y. S.

    2014-09-01

    The energetically most stable orthorhombic structure of OsB2 and IrB2 is dynamically stable for OsB2 but unstable for IrB2. Both diborides have substantially lower shear strength in their easy slip systems than their metal counterparts. This is attributed to an easy sliding facilitated by out-of-plane weakening of metallic Os-Os bonds in OsB2 and by an in-plane bond splitting instability in IrB2. A much higher shear resistance of Os-B and B-B bonds than Os-Os ones is found, suggesting that the strengthened Os-B and B-B bonds are responsible for hardness enhancement in OsB2. In contrast, an in-plane electronic instability in IrB2 limits its strength. The electronic structure of deformed diborides suggests that the electronic instabilities of 5d orbitals are their origin of different bond deformation paths. Neither IrB2 nor OsB2 can be intrinsically superhard.

  4. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Science.gov (United States)

    2010-04-01

    ... hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil... gum, kelp, methylcellulose, plantago seed (psyllium), polycarbophil tragacanth, and xanthan gum) as..., and hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium...

  5. DAMPING PERFORMANCE OF EUCOMMIA ULMOIDES GUM

    Institute of Scientific and Technical Information of China (English)

    Ji-chuan Zhang; Zhao-hong Xue; Rui-fang Yan

    2011-01-01

    Eucommia ulmoides gum (EU gum), known as gutta percha in Southeast Asia, is a natural polymer with double characteristics of rubber and plastic. In present paper, tanδ-T curve and hysteresis loss (HL) were chosen to characterize its damping property. The results indicated that its tanδvalue would increase with rising of temperature when T> 0°C and form another damping peak at 40-80°C besides Tg peak. This phenomenon resulted fiom meltage of crystals of EU gum could increase its damping property at ambient-high temperature. Its tanδ value even exceeded those of conventional damping rubbers, such as nitrile-butadiene rubber (NBR) and chlorinated isobutene-isoprene rubber (CIIR).

  6. Design, formulation and evaluation of caffeine chewing gum

    Directory of Open Access Journals (Sweden)

    Abolfazl Aslani

    2013-01-01

    Conclusion: In this study, 20 and 50 mg caffeine gums with suitable and desirable properties (i.e., good taste and satisfactory release were formulated. The best flavor for caffeine gum was cinnamon. Both kinds of 20 and 50 mg gums succeeded in content uniformity test.

  7. 21 CFR 184.1343 - Locust (carob) bean gum.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Locust (carob) bean gum. 184.1343 Section 184.1343... Listing of Specific Substances Affirmed as GRAS § 184.1343 Locust (carob) bean gum. (a) Locust (carob) bean gum is primarily the macerated endosperm of the seed of the locust (carob) bean tree,...

  8. Biobased alternatives to guar gum as tackifiers for hydromulch

    Science.gov (United States)

    Guar gum, obtained from guar [Cyamopsis tetragonoloba (L.) Taub.] seeds, is currently the principal gum used as a tackifier (binder) for hydraulically-applied mulches (hydromulches) used in erosion control. The oil industry’s increased use of guar gum in hydraulic fracturing together with lower glo...

  9. Quantification and Qualification of Bacteria Trapped in Chewed Gum

    NARCIS (Netherlands)

    Wessel, Stefan W.; van der Mei, Henny C.; Morando, David; Slomp, Anje M.; van de Belt-Gritter, Betsy; Maitra, Amarnath; Busscher, Henk J.

    2015-01-01

    Chewing of gum contributes to the maintenance of oral health. Many oral diseases, including caries and periodontal disease, are caused by bacteria. However, it is unknown whether chewing of gum can remove bacteria from the oral cavity. Here, we hypothesize that chewing of gum can trap bacteria and r

  10. Gum Arabic authentication and mixture quantification by near infrared spectroscopy

    DEFF Research Database (Denmark)

    Dong, Yongjiang; Sørensen, Klavs Martin; He, Sailing

    2017-01-01

    A rapid and reliable method is developed for Gum Arabic authentication based on Near Infrared (NIR) spectroscopy and chemometric methods. On a large industrial collection of authentic gum Arabics, the two major Acacia gum species, Acacia senegal and Acacia seyal could be assigned perfectly...

  11. Quantification and Qualification of Bacteria Trapped in Chewed Gum

    NARCIS (Netherlands)

    Wessel, Stefan W.; van der Mei, Henny C.; Morando, David; Slomp, Anje M.; van de Belt-Gritter, Betsy; Maitra, Amarnath; Busscher, Henk J.

    2015-01-01

    Chewing of gum contributes to the maintenance of oral health. Many oral diseases, including caries and periodontal disease, are caused by bacteria. However, it is unknown whether chewing of gum can remove bacteria from the oral cavity. Here, we hypothesize that chewing of gum can trap bacteria and

  12. Rheological Modeling and Characterization of Ficus platyphylla Gum Exudates

    Directory of Open Access Journals (Sweden)

    Nnabuk O. Eddy

    2013-01-01

    Full Text Available Ficus platyphylla gum exudates (FP gum have been analyzed for their physicochemical parameters and found to be ionic, mildly acidic, odourless, and yellowish brown in colour. The gum is soluble in water, sparingly soluble in ethanol, and insoluble in acetone and chloroform. The nitrogen (0.39% and protein (2.44% contents of the gum are relatively low. The concentrations of the cations were found to increase according to the following trend, Mn>Fe>Zn>Pb>Cu>Mg>Cd>Ca. Analysis of the FTIR spectrum of the gum revealed vibrations similar to those found in polysaccharides while the scanning electron micrograph indicated that the gum has irregular molecular shapes, arranged randomly. The intrinsic viscosity of FP gum estimated by extrapolating to zero concentrations in Huggins, Kraemer, Schulz-Blaschke, and Martin plots has an average value of 7 dL/g. From the plots of viscosity versus shear rate/speed of rotation and also that of shear stress versus shear rate, FP gum can be classified as a non-Newtonian gum with characteristics-plastic properties. Development of the Master_s curve for FP gum also indicated that the gum prefers to remain in a dilute domain (Cgum (calculated from Arrhenius-Frenkel-Eyring plot was relatively low and indicated the presence of fewer inter- and intramolecular interactions.

  13. Compositional analysis and rheological properties of gum kondagogu (Cochlospermum gossypium): a tree gum from India.

    Science.gov (United States)

    Vinod, V T P; Sashidhar, R B; Sarma, V U M; Vijaya Saradhi, U V R

    2008-03-26

    Gum kondagogu ( Cochlospermum gossypium) is a tree exudate gum that belongs to the family Bixaceae. Compositional analysis of the gum by HPLC and LC-MS revealed uronic acids to be the major component of the polymer ( approximately 26 mol %). Furthermore, analysis of the gum by GC-MS indicated the presence of sugars such as arabinose (2.52 mol %), mannose (8.30 mol %), alpha- d-glucose (2.48 mol %), beta- d-glucose (2.52 mol %), rhamnose (12.85 mol %), galactose (18.95 mol %), d-glucuronic acid (19.26 mol %), beta- d-galactouronic acid (13.22 mol %), and alpha- d-galacturonic acid (11.22 mol %). Gum kondagogu, being rich in rhamnose, galactose, and uronic acids, can be categorized on the basis of its sugar composition as a rhamnogalacturonan type of gum. The rheological measurements performed on the gum suggest that above 0.6% (w/v) it shows a Newtonian behavior and shear rate thinning behavior as a function of gum concentration. The viscoelastic behavior of gum kondagogu solutions (1 and 2%) in aqueous as well as in 100 mM NaCl solution exhibits a typical gel-like system. The G' (viscous modulus)/ G'' (elastic modulus) ratios of native gum kondagogu (1 and 2%) in aqueous solution were found to be 1.89 and 1.85 and those in 100 mM NaCl to be 1.54 and 2.2, respectively, suggesting a weak gel-like property of the polymer. Crossover values of G' and G'' were observed to be at frequencies of 0.432 Hz for 1% and 1.2 Hz for 2% for native gum in aqueous condition, indicating a predominantly liquid- to solid-like behavior, whereas crossover values of 2.1 Hz for 1% and 1.68 Hz for 2% gum in 100 mM NaCl solution suggest a larger elastic contribution.

  14. Flavor release measurement from gum model system

    DEFF Research Database (Denmark)

    Ovejero-López, I.; Haahr, Anne-Mette; van den Berg, Frans W.J.

    2004-01-01

    Flavor release from a mint-flavored chewing gum model system was measured by atmospheric pressure chemical ionization mass spectroscopy (APCI-MS) and sensory time-intensity (TI). A data analysis method for handling the individual curves from both methods is presented. The APCI-MS data are ratio...... composition can be measured by both instrumental and sensory techniques, providing comparable information. The peppermint oil level (0.5-2% w/w) in the gum influenced both the retronasal concentration and the perceived peppermint flavor. The sweeteners' (sorbitol or xylitol) effect is less apparent. Sensory...

  15. Chewing-gum preservative induced toxidermic vasculitis.

    Science.gov (United States)

    Moneret-Vautrin, D A; Faure, G; Bene, M C

    1986-09-01

    This paper reports the case of a young female patient who presented with a cutaneous urticarial disseminated eruption. Drug-induced side effects were eliminated, and the only recent dietary change was the regular use of chewing-gums containing chlorophylla (E140), menthol and BHT (butylhydroxytoluene). Immunohistological analysis of a cutaneous lesion revealed signs of vasculitis. Within 1 week after stopping chewing gum, the eruption subsided. Oral provocation tests at 4-day intervals confirmed the responsibility of BHT by the reinduction of the cutaneous signs after a few hours.

  16. Revealing the micromechanisms behind semi-solid metal deformation with time-resolved X-ray tomography

    Science.gov (United States)

    Kareh, K. M.; Lee, P. D.; Atwood, R. C.; Connolley, T.; Gourlay, C. M.

    2014-07-01

    The behaviour of granular solid-liquid mixtures is key when deforming a wide range of materials from cornstarch slurries to soils, rock and magma flows. Here we demonstrate that treating semi-solid alloys as a granular fluid is critical to understanding flow behaviour and defect formation during casting. Using synchrotron X-ray tomography, we directly measure the discrete grain response during uniaxial compression. We show that the stress-strain response at 64-93% solid is due to the shear-induced dilation of discrete rearranging grains. This leads to the counter-intuitive result that, in unfed samples, compression can open internal pores and draw the free surface into the liquid, resulting in cracking. A soil mechanics approach shows that, irrespective of initial solid fraction, the solid packing density moves towards a constant value during deformation, consistent with the existence of a critical state in mushy alloys analogous to soils.

  17. Graft (partially carboxymethylated guar gum-g-poly vinyl sulfonic acid) copolymer: from synthesis to applications.

    Science.gov (United States)

    Yadav, Mithilesh; Srivastav, Abhishek; Verma, Shiv Kumar; Behari, Kunj

    2013-09-12

    The aim of the paper is to study the physico-chemical phenomenon of synthesized graft copolymer (carboxymethylated guar gum-g-vinylsulfonic acid). The reaction optimum conditions for grafting has also been determined by studying the effect of vinylsulfonic acid, hydrogen ion, peroxymonosulphate, glycolic acid concentration and carboxymethylated guar gum along with time and temperature. Experimental results show that maximum grafting has been obtained at 1.8 g dm(-3) concentration of partially carboxymethylated guar gum and 5.3 × 10(-2) mol dm(-3) concentration of vinylsulfonic acid. It has been observed that grafting ratio, add on, conversion, efficiency increase up to 4.0 × 10(-3) mol dm(-3) of hydrogen ion, 4 × 10(-3) mol dm(-3) of glycolic acid, 14 × 10(-3) mol dm(-3) of peroxymonosulphate and 35 °C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling, flocculating, metal ion uptake and resistance to biodegradability properties of partially carboxymethylated guar gum-g-vinylsulfonic acid have been determined.

  18. Efek Penambahan -Galaktosidase Famili 27 Glikosida Hidrolase Bacillus Halodurans terhadap Kekentalan Guar Gum

    Directory of Open Access Journals (Sweden)

    Andian Ari Anggraeni

    2008-10-01

    Full Text Available Penelitian ini bertujuan untuk mempelajari aktivitas protein hasil translasi gen a-galaktosidase dari Bacillus halodurans famili 27 glikosida hidrolase dengan cara mengamati pengaruh penambahan protein terhadap kekentalan larutan guar gum. Penelitian ini dilakukan dengan menggunakan metode eksperimen. a-Galaktosidase adalah enzim yang mengkatalisasi hidrolisis ikatan a-1,6-galaktosida dari terminal non-reducing pada oligosakarida, liposakarida dan/atau polisakarida yang mengandung galaktosa. Protein rekombinan yang diekspresikan oleh gen  agalaktosidase BH1870 Bacillus halodurans dipurifikasi menggunakan His-binding metal affinity chromatography. Uji aktivitas dilakukan dengan menggunakan substrat guar gum pada beberapa interval suhu, yaitu 37, 45, 55 dan 65o C. Enzim ini mampu menghidrolisa guar gum pada suhu 37 oC, yang ditunjukkan dengan penurunan kekentalan larutan guar gum.  Namun, enzim ini tidak stabil pada suhu yang lebih besar dari 37 oC. Beberapa residu asam amino yang dianggap penting bagi aktivitas hidrolisis enzim famili 27 ternyata tidak terdapat pada B. halodurans a-galaktosidase. Ketiadaan residu ini mungkin dapat mempengaruhi kestabilan enzim pada suhu tinggi. Untuk membuktikan asumsi ini, diperlukan studi lanjut tentang site-directed mutagenesis pada residu-residu ini.

  19. Evaluation of Release Retarding Property of Gum Damar and Gum Copal in Combination with Hydroxypropyl Methylcellulose

    OpenAIRE

    V M Fulbandhe; C R Jobanputra; K J Wadher; M J Umekar; Bhoyar, G. S.

    2012-01-01

    The formulations consisting of a hydrophilic and hydrophobic material were investigated for effect on drug-release pattern from the matrices. Gum damar and gum copal being water-insoluble were used to study the efficiency of combined matrices to sustain the release of drug. Hydroxypropyl methylcellulose K100M and diclofenac sodium were used as the hydrophilic material and model drug, respectively. The influence of concentration of hydroxypropyl methylcellulose on drug release pattern of hydro...

  20. Chewing gum differentially affects aspects of attention in healthy subjects.

    Science.gov (United States)

    Tucha, Oliver; Mecklinger, Lara; Maier, Kerstin; Hammerl, Marianne; Lange, Klaus W

    2004-06-01

    In a study published previously in this journal (Wilkinson et al., 2002), the effect of chewing gum on cognitive functioning was examined. The results of this study indicated that chewing a piece of gum results in an improvement of working memory and of both immediate and delayed recall of words but not of attention. In the present study, memory and a variety of attentional functions of healthy adult participants were examined under four different conditions: no chewing, mimicking chewing movements, chewing a piece of tasteless chewing gum and chewing a piece of spearmint flavoured chewing gum. The sequence of conditions was randomised across participants. The results showed that the chewing of gum did not improve participants' memory functions. Furthermore, chewing may differentially affect specific aspects of attention. While sustained attention was improved by the chewing of gum, alertness and flexibility were adversely affected by chewing. In conclusion, claims that the chewing a gum improves cognition should be viewed with caution.

  1. Linear Rheology of Guar Gum Solutions

    NARCIS (Netherlands)

    Wientjes, Roland H.W.; Duits, Michel H.G.; Jongschaap, Rob J.J.; Mellema, Jorrit

    2000-01-01

    We have investigated the linear viscoelastic behavior of guar gum solutions as a function of frequency, temperature, polymer concentration, and molecular weight. This was done to sort out the importance of different relaxation mechanisms like reptation or the breakup of physical bonds. In the kilohe

  2. Enzymatic production of polysaccharides from gum tragacanth

    DEFF Research Database (Denmark)

    2014-01-01

    Plant polysaccharides, relating to the field of natural probiotic components, can comprise structures similar to human milk oligosaccharides. A method for enzymatic hydrolysis of gum tragacanth from the bush-like legumes of the genus Astragalus, using a combination of pectin hydrolases...

  3. 21 CFR 582.3336 - Gum guaiac.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Gum guaiac. 582.3336 Section 582.3336 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives §...

  4. Influence of thermal treatments and plastic deformation on the atomic mobility in Zr{sub 50.7}Cu{sub 28}Ni{sub 9}Al{sub 12.3} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, J.C.; Pelletier, J.M., E-mail: jean-marc.pelletier@insa-lyon.fr

    2014-12-05

    Highlights: • Atomic mobility in Zr-based metallic glass were evaluated by DMA and nanoindentation. • Atomic mobility is reduced by physical aging while increased by plastic deformation. • The atomic mobility in metallic glasses are related to concentration of “defects”. • Value of the Kohlrausch exponent β{sub KWW} in the Zr-based metallic glass is around 0.5. - Abstract: The atomic mobility in Zr{sub 50.7}Cu{sub 28}Ni{sub 9}Al{sub 12.3} bulk metallic glass has been evaluated as a function of temperature and the influence of different treatments (thermal annealing, plastic deformation) has been investigated using mechanical spectroscopy and nanoindentation technique. In particular the loss factor has been measured. This parameter is connected to the energy loss during the application of a periodic stress and therefore is sensitive to atomic movements. Master curves can be obtained, confirming the validity of the time–temperature superposition principle. The atomic mobility is reduced during physical aging (also called structural relaxation) but increased after a plastic deformation (a rejuvenation of the material is then induced). In the framework of the nanoindentation tests and mechanical spectroscopy, the concentration of “defects” in metallic glasses increases by deformation (i.e. cold-rolling) while decreases after structural relaxation and crystallization. These results are discussed using the concept of quasi-point defects, which assist the atomic movements.

  5. Exceptional adsorption-induced cluster and network deformation in the flexible metal-organic framework DUT-8(Ni) observed by in situ X-ray diffraction and EXAFS.

    Science.gov (United States)

    Bon, Volodymyr; Klein, Nicole; Senkovska, Irena; Heerwig, Andreas; Getzschmann, Jürgen; Wallacher, Dirk; Zizak, Ivo; Brzhezinskaya, Maria; Mueller, Uwe; Kaskel, Stefan

    2015-07-14

    The "gate opening" mechanism in the highly flexible MOF Ni2(2,6-ndc)2dabco (DUT-8(Ni), DUT = Dresden University of Technology) with unprecedented unit cell volume change was elucidated in detail using combined single crystal X-ray diffraction, in situ XRD and EXAFS techniques. The analysis of the crystal structures of closed pore (cp) and large pore (lp) phases reveals a drastic and unique unit cell volume expansion of up to 254%, caused by adsorption of gases, surpassing other gas-pressure switchable MOFs significantly. To a certain extent, the structural deformation is specific for the guest molecule triggering the transformation due to subtle differences in adsorption enthalpy, shape, and kinetic diameter of the guest. Combined adsorption and powder diffraction experiments using nitrogen (77 K), carbon dioxide (195 K), and n-butane (272.5 K) as a probe molecules reveal a one-step structural transformation from cp to lp. In contrast, adsorption of ethane (185 K) or ethylene (169 K) results in a two-step transformation with the formation of intermediate phases. In situ EXAFS during nitrogen adsorption was used for the first time to monitor the local coordination geometry of the metal atoms during the structural transformation in flexible MOFs revealing a unique local deformation of the nickel-based paddle-wheel node.

  6. Effect of stress-induced grain growth during room temperature tensile deformation on ductility in nanocrystalline metals

    Indian Academy of Sciences (India)

    Weichang Xu; Pinqiang Dai; Xiaolei Wu

    2010-10-01

    In the present study defect-free nanocrystalline (nc) Ni–Co alloys with the Co content ranging from 2.4–59.3% (wt.%) were prepared by pulse electrodeposition. X-ray diffraction analysis shows that only a single face-centred cubic solid solution is formed for each alloy and that the grain size reduces monotonically with increasing Co content, which is consistent with transmission electron microscopy (TEM) observations. In the nc Ni–Co alloys, both the ultimate tensile strength and the elongation to failure increase as the Co content increases. The TEM observations reveal that stress-induced grain growth during tensile deformation is significantly suppressed for the nc Ni–Co alloys rich in Co in sharp contrast to those poor in Co. We believe that sufficient solutes could effectively pin grain boundaries making grain boundary motions (e.g. grain boundary migration and/or grain rotation) during deformation more difficult. Thus, stress-induced grain growth is greatly suppressed. At the same time, shear banding plasticity instability is correspondingly delayed leading to the enhanced ductility.

  7. Influence of the localized initial plastic deformation on the effective thermomechanical response of metal-matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Roatta, A.; Turner, P.A.; Bertinetti, M.A.; Bolmaro, R.E.

    1999-11-01

    A generalized Eshelby model, allowing interaction among reinforcing particles under a Mori-Tanaka-like scheme, is presented. Different inclusion aspect ratios are studied in the elastic and incipient elastoplastic regime for a model SiC-Al composite. The solution of the field equations is obtained via an explicit algorithm that yields the interaction field in terms of the stress and strain variables. The particles and fibers are taken as purely elastic, and the matrix is regarded as elastic-perfectly plastic. Coefficients of thermal expansion (CTE) are calculated both under the assumption of purely elastic response and at the onset of plastic localized deformation. The simulated stress-strain curves show the influence of interaction stresses on macroscopic yield stress for different inclusion aspect ratios, with no consideration of matrix hardening. The model allows a good simulation of the thermomechanical behavior of composite materials and contributes to the understanding of the elastoplastic transition in stress-strain curves. It can also simply explain some of the most distinctive features of the mechanical behavior of composites. The model presents the possibility of controlling many input variables and geometries and simultaneously considering three-dimensional deformation of interacting inclusion-reinforced materials with low computational effort. Comparisons to experimental CTE and residual stresses are provided.

  8. Effect of GutsyGum(tm), A Novel Gum, on Subjective Ratings of Gastro Esophageal Reflux Following A Refluxogenic Meal.

    Science.gov (United States)

    Brown, Rachel; Sam, Cecilia H Y; Green, Tim; Wood, Simon

    2015-06-01

    Chewing gum alleviates symptoms of gastro-esophageal reflux (GER) following a refluxogenic meal. GutsyGum(tm), a chewing gum developed to alleviate the symptoms of GER contains calcium carbonate, with a proprietary blend of licorice extract, papain, and apple cider vinegar (GiGs®). The efficacy of GutsyGum(tm) was determined in alleviating the symptoms of GER after a refluxogenic meal compared to placebo gum. This double-blind, placebo-controlled-crossover trial with a one-week washout between treatments had 24 participants with a history of GER consume a refluxogenic meal and then chew GutsyGum(tm) or placebo gum. Participants completed GER symptom questionnaires, consisting of symptom based 10 cm Visual Analogue Scales, immediately following the meal and then at regular intervals out to four hours postmeal. Adjusted mean ± SEM heartburn score (15-min postmeal to 240 min) was significantly lower in GutsyGum(tm) than in placebo gum treatment (0.81 ± 0.20 vs. 1.45 ± 0.20 cm; p = 0.034). Mean acid reflux score was significantly lower in GutsyGum(tm) than in placebo treatment (0.72 ± 0.19 vs. 1.46 ± 0.19 cm; p = 0.013). There were no significant differences for any of the secondary outcomes. However, pain approached significance with less pain reported in GutsyGum(tm) versus placebo treatment (0.4 ± 0.2 vs. 0.9 ± 0.2 cm; p = 0.081). Although nausea (p = 0.114) and belching (p = 0.154) were lower following GutsyGum(tm), the difference was not statistically significant. GutsyGum(tm) is more effective than a placebo gum in alleviating primary symptoms of heartburn and acid reflux (Clinical Trial Registration: ACTRN12612000973819).

  9. Competition in the gum arabic market: a game theoretic modelling approach

    NARCIS (Netherlands)

    Rahim, A.; Ierland, van E.C.; Weikard, H.P.

    2010-01-01

    Gum arabic is mainly produced from two Acacias that are found in the gum belt of Sub-Saharan Africa. These are Acacia senegal that produces high quality gum and Acacia seyal that produces low quality gum. In recent years the gum market structure has changed and Sudan lost its near monopoly position

  10. Development of natural gum based fast disintegrating tablets of glipizide

    Directory of Open Access Journals (Sweden)

    Antesh Kumar Jha

    2012-01-01

    Full Text Available Dysphagia and risk of choking are leading causes of patient non-compliance in the self-administration of conventional tablets. To overcome these limitations of conventional tablets fast-disintegrating tablets were developed, using natural gums. Natural gums were evaluated for bulk swelling capacity. Powder mix containing natural gums and glipizide was evaluated for water sorption, swelling index and capillary action. For faster onset and immediate hypoglycemic action, the fast disintegrating tablets were prepared with various types of natural gums using the direct compression technique. Formulations containing guar gum disintegrated within a minute and fulfilled the official requirements for dispersible tablets. As the amount of guar gum increased, the friability increased and hardness decreased, resulting in a shorter wetting and disintegration time. Gum acacia and gum tragacanth did the opposite. The glipizide-loaded fast disintegrating tablet prepared with 18 mg of guar gum gave a friability of 0.46 ± 0.02%, content uniformity of 99.34 ± 0.82%, drug content of 99.15 ± 1.16%, wetting time of 39.0 ± 1.04 sec, hardness of 5.70 ± 1.41 Kg and disintegration time less than 30 sec, suggesting that it was a practical product with a good tablet property. In conclusion, natural gum based patient-friendly fast disintegrating tablets of glipizide can be successfully formulated.

  11. Beneficial properties of selenium incorporated guar gum nanoparticles against ischemia/reperfusion in cardiomyoblasts (H9c2).

    Science.gov (United States)

    Soumya, R S; Vineetha, V P; Salin Raj, P; Raghu, K G

    2014-11-01

    Nanotechnology for the treatment and diagnosis has been emerging recently as a potential area of research and development. In the present study, selenium incorporated guar gum nanoparticles have been prepared by nanoprecipitation and characterized by transmission electron microscopy and particle size analysis. The nanoparticles were screened for antioxidant potential (metal chelation, total reducing power and hydroxyl radical scavenging activity) and were evaluated against the cell line based cardiac ischemia/reperfusion model with special emphasis on oxidative stress and mitochondrial parameters. The cell based cardiac ischemia model was employed using H9c2 cell lines. Investigations revealed that there was a significant alteration (P ≤ 0.05) in the innate antioxidant status (glutathione↓, glutathione peroxidase↓, thioredoxin reductase↓, superoxide dismutase↓, catalase↓, lipid peroxidation↑, protein carbonyl↑, xanthine oxidase↑ and caspase 3 activity↑), mitochondrial functions (reactive oxygen species generation, membrane potential, and pore opening) and calcium homeostasis (calcium ATPase and intracellular calcium overload) during both ischemia and reperfusion. For comparative evaluation, selenium, guar gum and selenium incorporated guar gum nanoparticles were evaluated for their protective properties against ischemia/reperfusion. The study reveals that selenium incorporated guar gum nanoparticles were better at protecting the cells from ischemia/reperfusion compared to selenium and guar gum nanoparticles. The potent antioxidant capability shown by the sample in in vitro assays may be the biochemical basis of its better biological activity. Further, the nanodimensions of the particle may be the additional factor responsible for its better effect.

  12. Elastic Properties in Tension and Shear of High Strength Nonferrous Metals and Stainless Steel - Effect of Previous Deformation and Heat Treatment

    Science.gov (United States)

    Mebs, R W; Mcadam, D J

    1947-01-01

    A resume is given of an investigation of the influence of plastic deformation and of annealing temperature on the tensile and shear elastic properties of high strength nonferrous metals and stainless steels in the form of rods and tubes. The data were obtained from earlier technical reports and notes, and from unpublished work in this investigation. There are also included data obtained from published and unpublished work performed on an independent investigation. The rod materials, namely, nickel, monel, inconel, copper, 13:2 Cr-Ni steel, and 18:8 Cr-Ni steel, were tested in tension; 18:8 Cr-Ni steel tubes were tested in shear, and nickel, monel, aluminum-monel, and Inconel tubes were tested in both tension and shear. There are first described experiments on the relationship between hysteresis and creep, as obtained with repeated cyclic stressing of annealed stainless steel specimens over a constant load range. These tests, which preceded the measurements of elastic properties, assisted in devising the loading time schedule used in such measurements. From corrected stress-set curves are derived the five proof stresses used as indices of elastic or yield strength. From corrected stress-strain curves are derived the secant modulus and its variation with stress. The relationship between the forms of the stress-set and stress-strain curves and the values of the properties derived is discussed. Curves of variation of proof stress and modulus with prior extension, as obtained with single rod specimens, consist in wavelike basic curves with superposed oscillations due to differences of rest interval and extension spacing; the effects of these differences are studied. Oscillations of proof stress and modulus are generally opposite in manner. The use of a series of tubular specimens corresponding to different amounts of prior extension of cold reduction gave curves almost devoid of oscillation since the effects of variation of rest interval and extension spacing were

  13. 运用声发射技术监测金属塑性成型过程中润滑状态的研究%Study on the Lubricating Condition for Metal Plastic Deformation with Acoustic Emission Technique

    Institute of Scientific and Technical Information of China (English)

    贾园; 张守茁; 席镇; 高宏; 魏盛春; 孟维

    2009-01-01

    The acoustic emission (AE) technique was used in the experiment to monitor the lubricating condition in the metal plastic deformation. The AE signals of the frietion between the metal and the AE signals of the metal plastic deforma-tion were studied by monitoring the metal plastic deformation process and the friction process in the condition of lubricating or without lubricant. The results show that the AE signals generated by the different materials are unequal in the numerical value. The friction AE signals are less than the plastic deformation AE signals for the same materials. The AE technique could be used to monitor the lubricating condition in the course of the metal plastic deformation by the real time waveshape or mean value of the AE parameters.%为监测金属塑性成型过程中的润滑状态,采用运用声发射技术,通过对无润滑和有润滑时金属塑性变形过程和摩擦过程的监测及对比,分别研究了金属摩擦声发射信号和塑性变形声发射信号.结果表明,不同材料摩擦产生的声发射信号数值上大小不同,同种材料摩擦声发射信号数值上小于塑性变形声发射信号;采用声发射技术,基于实时波形和声发射信号参数的平均值都能监测金属塑性成型时的润滑状态.

  14. Bleeding gums: Duloxetine may be the cause

    Directory of Open Access Journals (Sweden)

    Balhara YPS

    2007-01-01

    Full Text Available Duloxetine is a newly introduced drug. It is being prescribed for the management of diabetic neuropathic pain and major depressive disorder. The most frequently observed adverse events with duloxetine are nausea, dry mouth and somnolence, constipation, diarrhea, decreased appetite, weight loss, feeling of fatigue, dizziness, somnolence, hypohidrosis, decreased libido and erectile dysfunction. One of the patients being prescribed the drug developed bleeding gums on being started with the drug which resolved on stopping it. We hereby report this case.

  15. Gellan gum : a new biomaterial for cartilage tissue engineering applications

    OpenAIRE

    2010-01-01

    Gellan gum is a polysaccharide manufactured by microbial fermentation of the Sphingomonas paucimobilis microorganism, being commonly used in the food and pharmaceutical industry. It can be dissolved in water, and when heated and mixed with mono or divalent cations, forms a gel upon lowering the temperature under mild conditions. In this work, gellan gum hydrogels were analyzed as cells supports in the context of cartilage regeneration. Gellan gum hydrogel discs were ch...

  16. How does chewing gum affect cognitive function? Reply to Scholey (2004).

    Science.gov (United States)

    Stephens, Richard; Tunney, Richard J

    2004-10-01

    Cognitive effects of glucose from chewing gum and other mechanisms can be investigated further when factors like the flavouring of the gum and the participants' familiarity with gum chewing are assessed.

  17. Guar gum: processing, properties and food applications-A Review.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, Bhupendar Singh

    2014-03-01

    Guar gum is a novel agrochemical processed from endosperm of cluster bean. It is largely used in the form of guar gum powder as an additive in food, pharmaceuticals, paper, textile, explosive, oil well drilling and cosmetics industry. Industrial applications of guar gum are possible because of its ability to form hydrogen bonding with water molecule. Thus, it is chiefly used as thickener and stabilizer. It is also beneficial in the control of many health problems like diabetes, bowel movements, heart disease and colon cancer. This article focuses on production, processing, composition, properties, food applications and health benefits of guar gum.

  18. Quantification and qualification of bacteria trapped in chewed gum.

    Science.gov (United States)

    Wessel, Stefan W; van der Mei, Henny C; Morando, David; Slomp, Anje M; van de Belt-Gritter, Betsy; Maitra, Amarnath; Busscher, Henk J

    2015-01-01

    Chewing of gum contributes to the maintenance of oral health. Many oral diseases, including caries and periodontal disease, are caused by bacteria. However, it is unknown whether chewing of gum can remove bacteria from the oral cavity. Here, we hypothesize that chewing of gum can trap bacteria and remove them from the oral cavity. To test this hypothesis, we developed two methods to quantify numbers of bacteria trapped in chewed gum. In the first method, known numbers of bacteria were finger-chewed into gum and chewed gums were molded to standard dimensions, sonicated and plated to determine numbers of colony-forming-units incorporated, yielding calibration curves of colony-forming-units retrieved versus finger-chewed in. In a second method, calibration curves were created by finger-chewing known numbers of bacteria into gum and subsequently dissolving the gum in a mixture of chloroform and tris-ethylenediaminetetraacetic-acid (TE)-buffer. The TE-buffer was analyzed using quantitative Polymerase-Chain-Reaction (qPCR), yielding calibration curves of total numbers of bacteria versus finger-chewed in. Next, five volunteers were requested to chew gum up to 10 min after which numbers of colony-forming-units and total numbers of bacteria trapped in chewed gum were determined using the above methods. The qPCR method, involving both dead and live bacteria yielded higher numbers of retrieved bacteria than plating, involving only viable bacteria. Numbers of trapped bacteria were maximal during initial chewing after which a slow decrease over time up to 10 min was observed. Around 10(8) bacteria were detected per gum piece depending on the method and gum considered. The number of species trapped in chewed gum increased with chewing time. Trapped bacteria were clearly visualized in chewed gum using scanning-electron-microscopy. Summarizing, using novel methods to quantify and qualify oral bacteria trapped in chewed gum, the hypothesis is confirmed that chewing of gum can trap

  19. Antiectoparasitic activity of the gum resin, gum haggar, from the East African plant, Commiphora holtziana.

    Science.gov (United States)

    Birkett, Michael A; Abassi, Sate Al; Kröber, Thomas; Chamberlain, Keith; Hooper, Antony M; Guerin, Patrick M; Pettersson, Jan; Pickett, John A; Slade, Robin; Wadhams, Lester J

    2008-05-01

    The mechanism of ixodid tick (Acari: Ixodidae) repellency by gum haggar, a resin produced by Commiphora holtziana (Burseraceae), was investigated by evaluating activity against the cattle tick, Boophilus microplus. In an arena bioassay, a hexane extract of the resin of C. holtziana exhibited a repellent effect lasting up to 5h. The hydrocarbon fraction of the resin extract was shown to account for the repellent activity, and was analysed by coupled gas chromatography-mass spectrometry (GC-MS). Major sesquiterpene hydrocarbons were tentatively identified as germacrene-D, delta-elemene and beta-bourbonene. The identity and stereochemistry of the former compound was confirmed as the (+)-isomer by peak enhancement using enantioselective GC, whereas the latter 2 compounds, which are most likely degradation products of germacrene-type precursors, were identified through isolation by preparative gas chromatography followed by microprobe-NMR spectroscopy. GC comparison of gum haggar with another resin, C. myrrha, which was inactive in the tick bioassay, showed that the latter contained much lower levels of these hydrocarbons. To assess the suitability of the gum haggar resin as a general acarine repellent, further tests were made on a major acarine pest of European and US animal husbandry systems, the red poultry mite, Dermanyssus gallinae (Acari: Dermanyssidae). Gum haggar extract, and the isolated hydrocarbon fraction, showed strong repellent effects in an olfactometer assay, and again gum myrrh showed no effect. These findings provide a scientific basis for the observed anti-tick properties of gum haggar, and demonstrate the potential for its development as a general acarine repellent for use in animal husbandry systems.

  20. Tensile deformation mechanisms of an in-situ Ti-based metallic glass matrix composite at cryogenic temperature.

    Science.gov (United States)

    Bai, J; Li, J S; Qiao, J W; Wang, J; Feng, R; Kou, H C; Liaw, P K

    2016-08-31

    Remarkable tensile ductility was first obtained in an in-situ Ti-based bulk metallic glass (BMG) composite at cryogenic temperature (77 K). The novel cryogenic tensile plasticity is related to the effective accommodation of ductile body-centered cubic dendrites at 77 K, characteristic of the prevailing slip bands and dislocations, as well as lattice disorder, which can effectively hinder the propagation of critical shear bands. The greatly increased yield strength of dendrites contributes to the high yield strength of composite at 77 K. A trend of stronger softening is observed at low temperature, and a criterion is proposed to understand the softening behavior. The current research could also provide a guidance to the promising cryogenic application of these new advanced BMG composites.

  1. Tensile deformation mechanisms of an in-situ Ti-based metallic glass matrix composite at cryogenic temperature

    Science.gov (United States)

    Bai, J.; Li, J. S.; Qiao, J. W.; Wang, J.; Feng, R.; Kou, H. C.; Liaw, P. K.

    2016-08-01

    Remarkable tensile ductility was first obtained in an in-situ Ti-based bulk metallic glass (BMG) composite at cryogenic temperature (77 K). The novel cryogenic tensile plasticity is related to the effective accommodation of ductile body-centered cubic dendrites at 77 K, characteristic of the prevailing slip bands and dislocations, as well as lattice disorder, which can effectively hinder the propagation of critical shear bands. The greatly increased yield strength of dendrites contributes to the high yield strength of composite at 77 K. A trend of stronger softening is observed at low temperature, and a criterion is proposed to understand the softening behavior. The current research could also provide a guidance to the promising cryogenic application of these new advanced BMG composites.

  2. Formulation development and evaluation of metformin chewing gum with bitter taste masking

    Directory of Open Access Journals (Sweden)

    Sayed Abolfazl Mostafavi

    2014-01-01

    Conclusion: Metfornin chewing gum had suitable appearance and appropriate invitro characteristics that fallow the pharmacopeia suggestions. This chewable gum showed bitterness suppression with a suitable release rate.

  3. Stabilization of emulsions by gum tragacanth (Astragalus spp.) correlates to the galacturonic acid content and methoxylation degree of the gum

    DEFF Research Database (Denmark)

    Ahmadi Gavlighi, Hassan; Meyer, Anne S.; Abang Zaidel, Dayang Norulfairuz

    2013-01-01

    –270 mg/g), and galactose (∼40–140 mg/g), and also contained fucose, rhamnose, and glucose. The ability of the gums to act as stabilizers in whey protein isolate based emulsions varied. The best emulsion stabilization effect, measured as lowest creaming index ratio after 20 days, was obtained with the A....... fluccosus gum. The emulsion stabilization effect correlated linearly and positively to the methoxylation degree, and galacturonic acid content of the gums, but not to acetyl or fucose content. A particularly high correlation was found between methoxyl level in the soluble gum part and emulsion stabilization...

  4. Effect of gums on the rheological characteristics and microstructure of acid-induced SPI-gum mixed gels.

    Science.gov (United States)

    Chang, Yuan-Yuan; Li, Dong; Wang, Li-Jun; Bi, Chong-Hao; Adhikari, Benu

    2014-08-01

    The effect of addition of xanthan gum (XG) and guar gum (GG) on the rheological properties and microstructure of glucono-δ-lactone induced soy protein isolate (SPI)-XG gels and SPI-GG gels was investigated using steady and dynamic rheological tests, creep-recovery and confocal laser scanning microscopy (CLSM). Results showed that the apparent viscosity of SPI-gum (XG, GG) mixed solutions increased with the increase in the gum (XG, GG) concentration. The storage (G') and loss (G″) moduli of SPI-gum (XG, GG) mixed gels increased in the presence and increase in the gum (XG, GG) concentration. The Burger's model fitted the creep recovery data well (R(2)>0.919) and showed that both the instantaneous and equilibrium (retarded) elastic components of this model increased with the increase in SPI and gum concentrations. The proportion occupied by gum in mixed gels was found to increase with the increase in the concentration of gums which increased the density of protein aggregates in the mixed gels.

  5. The effect of high temperature plastic deformation on the thermal stability and microstructure of Zr{sub 55}Cu{sub 30}Ni{sub 5}Al{sub 10} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)], E-Mail: lliu2000@public.wh.hb.cn; Chen, Q. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Chan, K.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University, Hong Kong (China); Wang, J.F. [State Key Lab of Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Pang, G.K.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2007-03-25

    The plastic deformation of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} (numbers indicate at.%) bulk metallic glass (BMG) was conducted in the supercooled liquid region under uniaxial tension with various strain rates ranging from 8.3 x 10{sup -4} to 2 x 10{sup -2} s{sup -1}. It was found that the deformation behavior of the BMG is strongly dependent on strain rate. Thermal and structural investigations revealed that the plastic deformation reduced the thermal stability of Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} BMG and promoted crystallization or reordering of the amorphous structure. To clarify the correlation between strain and structure of the BMG, the sample that was deformed at a high strain rate and exhibited significant necking was selected for a detailed investigation of its structure in different parts (e.g., the tip, middle and end parts) by conventional and high-resolution transmission electron microscopy. It was found that a band crystalline structure with a strongly crystallographic orientation was formed at the tip part, while inhomogeneous nanocrystallization occurred in the middle parts, and the amorphous structure remained almost unchanged in the end part. The different structures observed in different parts of the deformed sample are attributed to the inhomogeneous deformation of the BMG at high strain rates.

  6. Toward understanding twin–twin interactions in hcp metals: Utilizing multiscale techniques to characterize deformation mechanisms in magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, B.M., E-mail: morrow@lanl.gov; Cerreta, E.K.; McCabe, R.J.; Tomé, C.N.

    2014-09-08

    The mechanical properties of hexagonal close-packed (hcp) metals depend heavily on both slip and twinning, and interactions between twins have important implications on hardening behavior. Electron backscatter diffraction (EBSD), as well as conventional, in situ straining, and high resolution (HR) transmission electron microscopy (TEM) are used to study these interactions. HRTEM is used to observe the twin boundary structure. Twin boundaries that deviate from the characteristic {101"¯2} twin planes at the macroscale are revealed to be a combination of perfect {101"¯2} boundaries and characteristic facets at the nanoscale. Faceting for tensile {101"¯2} twins adopts basal-prismatic (B-P) character, where basal planes in the matrix very nearly align with prism planes in the twin, or similarly, prism planes in the matrix align with basal planes in the twin. Such features play a significant role in twin boundaries, where faceting accommodates the large changes to boundary shape observed. in situ straining is used to study twin–twin interactions as they occur, and also detwinning behavior upon load reversal. During the initial interaction, considerable changes to the shape of the twin boundaries are observed, consistent with post-mortem analyses. On load reversal, detwinning is observed, and the interacting twins disengage from one another, however a change in boundary structure due to the interaction is retained.

  7. Gum Sensor: A Stretchable, Wearable, and Foldable Sensor Based on Carbon Nanotube/Chewing Gum Membrane.

    Science.gov (United States)

    Darabi, Mohammad Ali; Khosrozadeh, Ali; Wang, Quan; Xing, Malcolm

    2015-12-02

    Presented in this work is a novel and facile approach to fabricate an elastic, attachable, and cost-efficient carbon nanotube (CNT)-based strain gauge which can be efficiently used as bodily motion sensors. An innovative and unique method is introduced to align CNTs without external excitations or any complicated procedure. In this design, CNTs are aligned and distributed uniformly on the entire chewing gum by multiple stretching and folding technique. The current sensor is demonstrated to be a linear strain sensor for at least strains up to 200% and can detect strains as high as 530% with a high sensitivity ranging from 12 to 25 and high durability. The gum sensor has been used as bodily motion sensors, and outstanding results are achieved; the sensitivity is quite high, capable of tracing slow breathing. Since the gum sensor can be patterned into various forms, it has wide applications in miniaturized sensors and biochips. Interestingly, we revealed that our gum sensor has the ability to monitor humidity changes with high sensitivity and fast resistance response capable of monitoring human breathing.

  8. Formation and subdivision of deformation structures during plastic deformation

    DEFF Research Database (Denmark)

    Jakobsen, B.; Poulsen, H.F.; Lienert, U.;

    2006-01-01

    During plastic deformation of metals and alloys, dislocations arrange in ordered patterns. How and when these self-organization processes take place have remained elusive, because in situ observations have not been feasible. We present an x-ray diffraction method that provided data on the dynamics...... of individual, deeply embedded dislocation structures. During tensile deformation of pure copper, dislocation-free regions were identified. They showed an unexpected intermittent dynamics, for example, appearing and disappearing with proceeding deformation and even displaying transient splitting behavior....... Insight into these processes is relevant for an understanding of the strength and work-hardening of deformed materials....

  9. Effect of pass schedule and groove design on the metal deformation of 38MnVS6 in the initial passes of hot rolling

    Indian Academy of Sciences (India)

    R S Nalawade; V R Marje; G Balachandran; V Balasubramanian

    2016-01-01

    The deformation behaviour of a hot rolled micro-alloyed steel bar of grade 38MnVS6 was examined using an FEM model during the initial passes in a blooming mill, as a function of three different pass schedules,roll groove depth, collar taper angle and corner radius. The simulations predicted the effective strain penetration,load, torque, fish tail billet end shapes, and metal flow behaviour at a chosen temperature, mill rpm and draft. The model predictions were validated for typical groove geometry and a typical pass schedule. Lower collar taper angle, lower corner radius and higher depth of groove in hot rolling enabled achievement of higher strain penetration, higher mill load and lower fish tail formation. The present study establishes the capability of the model to improve the internal quality of the rolled billet as measured by effective strain which was corroborated to the rolled bar macrostructure and microstructure. The model enables yield improvement by the choice of draft to minimise fish tail losses. The surface quality is improved by the ability to avoid fin formation that occurs at certain conditions of rolling. Thus, the groove geometry, roll pass schedule and rolling mill parameters and temperature can be optimised for best product quality and yield.

  10. Refined Deformation Model for Metal-Composite Plates of Regular Layered Structure in Bending Under Conditions of Steady-State Creep

    Science.gov (United States)

    Yankovskii, A. P.

    2017-01-01

    The problem of the mechanical behavior of metal-composite plates of regular layered structure in bending under conditions of steady-state creep of all phase materials is formulated. Equations describing, with various degrees of accuracy, the stress and viscous creep states of such plates with account of their weakened resistance to transverse shears are obtained. The relations of the classical Kirkhoff theory, the nonclassical Reissner theory results, and the second variant of Timoshenko theory result as special cases of these equations. For asymmetrically loaded annular plates with one edge clamped and statically loaded other one, a simplified variant of the refined theory, whose complexity in practical realization is comparable to that of the Reissner theory, is developed. The bending deformations of such annular plates at different levels of thermal actions are calculated. It is shown that, with increasing temperature, the accuracy of calculations within the framework of the traditional theories decreases sharply and neither of them provides an accuracy for the calculated compliance of the structure even within 20%.

  11. Gellan Gum: Fermentative Production, Downstream Processing and Applications

    Directory of Open Access Journals (Sweden)

    Ishwar B. Bajaj

    2007-01-01

    Full Text Available The microbial exopolysaccharides are water-soluble polymers secreted by microorganisms during fermentation. The biopolymer gellan gum is a relatively recent addition to the family of microbial polysaccharides that is gaining much importance in food, pharmaceutical and chemical industries due to its novel properties. It is commercially produced by C. P. Kelco in Japan and the USA. Further research and development in biopolymer technology is expected to expand its use. This article presents a critical review of the available information on the gellan gum synthesized by Sphingomonas paucimobilis with special emphasis on its fermentative production and downstream processing. Rheological behaviour of fermentation broth during fermentative production of gellan gum and problems associated with mass transfer have been addressed. Information on the biosynthetic pathway of gellan gum, enzymes and precursors involved in gellan gum production and application of metabolic engineering for enhancement of yield of gellan gum has been specified. Characteristics of gellan gum with respect to its structure, physicochemical properties, rheology of its solutions and gel formation behaviour are discussed. An attempt has also been made to review the current and potential applications of gellan gum in food, pharmaceutical and other industries.

  12. 77 FR 43857 - Xanthan Gum From Austria and China

    Science.gov (United States)

    2012-07-26

    ... publishing the notice in the Federal Register of July 12, 2012 (77 FR 34997). The conference was held in... COMMISSION Xanthan Gum From Austria and China Determinations On the basis of the record \\1\\ developed in the... Austria and China of xanthan gum, provided for in subheading 3913.90.20 of the Harmonized Tariff...

  13. 78 FR 43226 - Xanthan Gum From Austria and China

    Science.gov (United States)

    2013-07-19

    ... Register of February 27, 2013 (78 FR 13379). The hearing was held in Washington, DC, on May 23, 2013, and... COMMISSION Xanthan Gum From Austria and China Determinations On the basis of the record \\1\\ developed in the... with material injury by reason of imports from China of xanthan gum provided for in subheading...

  14. Fighting Gum Disease: Risk Factors, Treatment and Research

    Science.gov (United States)

    ... treat periodontal disease. Read More "Fighting Gum Disease" Articles Keep Gum Disease Away! / Take Care of Your Teeth / Risk Factors, Treatment and Research Fall 2010 Issue: Volume 5 Number 3 Page 11 ... | Viewers & Players Friends of the National Library of Medicine (FNLM)

  15. Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

  16. Safety assessment and caloric value of partially hydrolyzed guar gum.

    Science.gov (United States)

    Finley, John W; Soto-Vaca, Adriana; Heimbach, James; Rao, T P; Juneja, Lekh Raj; Slavin, Joanne; Fahey, George C

    2013-02-27

    Guar gum and partially hydrolyzed guar gum (PHGG) are food ingredients that have been available for many years. PHGG is the partially hydrolyzed product from guar gum obtained from the Indian cluster bean (Cyanopsis tetragonolopus). The gum (CAS Registry No. 9000-30-0) is composed of galactomannan, a gel-forming polysaccharide with a molecular weight ranging from 200 to 300 kDa. The intact and partially hydrolyzed forms have multiple food applications. The intact material can be used to control the viscosity, stability, and texture of foods. PHGG is highly soluble and has little physical impact on foods. Both forms are indigestible but are excellent sources of fermentable dietary fiber. The caloric value of intact guar gum is accepted as 2.0, whereas the caloric value of PHGG has not been firmly established. It is the goal of this paper to review the chemistry, safety, in vivo effects, and caloric value of PHGG.

  17. INTERMOLECULAR AND INTRAMOLECULAR INTERACTIONS OF POLYMER GUAR GUM IN SOLUTIONS

    Institute of Scientific and Technical Information of China (English)

    Yun-fei Yan; Hai-yang Yang; Wen-yong Liu; Ping-ping Zhu; Ping-sheng He

    2005-01-01

    The tetrahedral borate ion can crosslink with polymer guar gum in aqueous solutions. If the concentration of guar gum is less than 0.045 g/dL, the intramolecular interaction between guar gum and borate ion increases due to the formation of crosslinks. As a result, the polymer chains of guar gum in solution shrink in size and the reduced viscosity of polymer solution decreases accordingly. On the other hand, if the concentration of guar gum is greater than 0.045 g/dL, the intermolecular interaction becomes apparent due to the same reason. The polymer chains, therefore, associate together and the reduced viscosity of polymer solution increases considerably. According to this technique, the critical concentration c*,presented by de-Gennes[1], is determined successfully.

  18. Comparative study of gum arabic and PVP as stabilizing agents for synthesis of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Andressa A.; Leal, Jessica; Geraldes, Adriana N.; Lugao, Ademar B., E-mail: andressa_alvess@yahoo.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Use Colloidal metallic nanoparticles such as gold nanoparticles have received a great attention, due in part to their specific properties and potential applications. Control of size and uniformity of nanoparticles is important to prevent aggregation. High-molecular-weight polymers were used as stabilizer agents. Natural polymers, such as gum Arabic, are used as stabilizer because of capping nanoparticles behavior and present advantages such as solubility, non- toxicity and its compatibility for pharmaceutical and biomedical applications. Previous studies showed that the hydrophilic group of Poly(vinyl pyrrolidone) (PVP) caused repulsion on gold nanoparticles surface because steric interactions with polymer, for this reason this kind of polymers could be used as stabilizer agent. The aim of this work is to study the synthesis and stabilization of gold nanoparticles with PVP and gum Arabic using gamma radiation. The results obtained by samples analysis using UV-Visible showed that the gamma irradiation doses influenced the nanoparticles formation by PVP but that is not the case with the GA, because for smaller quantity of Arabic gum in different doses produced and stabilized nanoparticles. The samples were observed for 20 days and showed stability. We have obtained preliminary results showed that the use of radiation is applicable to the formation of gold nanoparticles. (author)

  19. Potentiality of the “Gum Metal” titanium-based alloy for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gordin, D.M. [Institut des Sciences Chimiques de Rennes (UMR CNRS 6226), INSA Rennes, 20 Avenue des Buttes de Coësmes, F-35043 Rennes Cedex (France); Ion, R. [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vasilescu, C.; Drob, S.I. [Institute of Physical Chemistry “Ilie Murgulescu” of Romanian Academy, Spl. Independentei 202, 060021 Bucharest (Romania); Cimpean, A. [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Gloriant, T., E-mail: Thierry.Gloriant@insa-rennes.fr [Institut des Sciences Chimiques de Rennes (UMR CNRS 6226), INSA Rennes, 20 Avenue des Buttes de Coësmes, F-35043 Rennes Cedex (France)

    2014-11-01

    In this study, the “Gum Metal” titanium-based alloy (Ti–23Nb–0.7Ta–2Zr–1.2O) was synthesized by melting and then characterized in order to evaluate its potential for biomedical applications. Thus, the mechanical properties, the corrosion resistance in simulated body fluid and the in vitro cell response were investigated. It was shown that this alloy presents a very high strength, a low Young's modulus and a high recoverable strain by comparison with the titanium alloys currently used in medicine. On the other hand, all electrochemical and corrosion parameters exhibited more favorable values showing a nobler behavior and negligible toxicity in comparison with the commercially pure Ti taken as reference. Furthermore, the biocompatibility tests showed that this alloy induced an excellent response of MC3T3-E1 pre-osteoblasts in terms of attachment, spreading, viability, proliferation and differentiation. Consequently, the “Gum Metal” titanium-based alloy processes useful characteristics for the manufacturing of highly biocompatible medical devices. - Highlights: • The Gum Metal alloy composition was synthesized by melting in this study. • Appropriate mechanical properties for biomedical applications were obtained. • High corrosion resistance in simulated body fluids was observed. • Excellent in-vitro cell response was evidenced.

  20. Evaluation of Sterculia foetida gum as controlled release excipient.

    Science.gov (United States)

    Chivate, Amit Ashok; Poddar, Sushilkumar Sharatchandra; Abdul, Shajahan; Savant, Gaurav

    2008-01-01

    The purpose of the research was to evaluate Sterculia foetida gum as a hydrophilic matrix polymer for controlled release preparation. For evaluation as a matrix polymer; characterization of Sterculia foetida gum was done. Viscosity, pH, scanning electronmicrographs were determined. Different formulation aspects considered were: gum concentration (10-40%), particle size (75-420 microm) and type of fillers and those for dissolution studies; pH, and stirring speed were considered. Tablets prepared with Sterculia foetida gum were compared with tablets prepared with Hydroxymethylcellulose K15M. The release rate profiles were evaluated through different kinetic equations: zero-order, first-order, Higuchi, Hixon-Crowell and Korsemeyer and Peppas models. The scanning electronmicrographs showed that the gum particles were somewhat triangular. The viscosity of 1% solution was found to be 950 centipoise and pH was in range of 4-5. Suitable matrix release profile could be obtained at 40% gum concentration. Higher sustained release profiles were obtained for Sterculia foetida gum particles in size range of 76-125 microm. Notable influences were obtained for type of fillers. Significant differences were also observed with rotational speed and dissolution media pH. The in vitro release profiles indicated that tablets prepared from Sterculia foetida gum had higher retarding capacity than tablets prepared with Hydroxymethylcellulose K15M prepared tablets. The differential scanning calorimetry results indicated that there are no interactions of Sterculia foetida gum with diltiazem hydrochloride. It was observed that release of the drug followed through surface erosion and anomalous diffusion. Thus, it could be concluded that Sterculia foetida gum could be used a controlled release matrix polymer.

  1. MARKET CHAIN ANALYSIS OF GUM ARABIC TRADE IN KENYA

    Directory of Open Access Journals (Sweden)

    M. O. Muga

    2013-06-01

    Full Text Available Quality, quantity, availability and economics are the key factors that affect the marketing of any product, irrespective of whether it is for domestic, national or international market. The consumer requires the product to be available in time, be of desired quality and quantity. The market of gum arabic is a good example of how the interplay of quality, quantity, availability and economics affect a product market. In Kenya, trade in gum arabic has remained informal due to inadequate marketing arrangements attributed to limited participation of gum arabic collectors in the development of the sector and a non-conducive business environment, which does not favor private sector expansion. This paper looked at the market chains of gum arabic, the stakeholders participating in the management and marketing of A. senegal products and the constraints to gum arabic production and collection within the Kenyan drylands. The results confirmed that the market chain of gum arabic was and is still poorly organized with only one company and a few individual traders being the major buyers. Wildlife related factors and price were the key constraints to gum arabic collection while production was limited by unreliable rainfall due prolonged droughts. Quality of the gum and road network determined the price with different grades attracting different rates per kilogram in different areas. SALTLICK and AWF were the chief stakeholders involved in A. senegal tree resources management. The study has shown that there is willingness of the locals to engage in full time gum collection if ready market can be availed to them. Nevertheless, numerous constraints need to be addressed to make gum arabic collection an attractive venture to the local communities’ key among them being the purchase price.

  2. The Reason Analysis on Deformation of Metal Hose of Oil Tank and Its Selection and Application%油罐金属软管的变形原因及选型和使用

    Institute of Scientific and Technical Information of China (English)

    郭守香

    2011-01-01

    Based on the reason analysis of three accidents from deformation of metal nose of oil tank, the matter needing attention in the selection, installation, utilization and management of metal hose is introduced in order to ensure the normal production and safety on oil tank area.%通过对三起油罐金属软管产生变形的原因分析,介绍了金属软管的选型、安装和使用管理应注意的事项,以保证油罐区的正常生产和安全。

  3. Effects of basil seed gum, Cress seed gum and Quince seed gum on the physical, textural and rheological properties of whipped cream.

    Science.gov (United States)

    Farahmandfar, Reza; Asnaashari, Maryam; Salahi, Mohammad Reza; Khosravi Rad, Tandis

    2017-05-01

    This study focuses on the physical, textural and rheological properties of low fat (LF) whipped cream with 30% fat content developed with Basil seed gum (BSG), Cress seed gum (CSG) and Quince seed gum (QSG) at the concentration of 0.1 and 0.3% (w/w) and comparison with high fat (HF) whipped cream sample (55%) as control. Flow curves were analyzed using Herschel bulkey and Carreau models through a fitting procedure. The rheological investigations confirmed that all samples were shear thinning fluid exhibiting a yield stress and thixotropy properties. The frequency sweep test showed that at the same gum concentration, mixes containing BSG have higher G', G″ and η(*) than those of mixes with QSG and CSG, and all mixes containing gum displayed weak gel-like behavior. Analysis showed that adding and increasing gums concentration caused to increased viscosity, hardness and overrun, leading to a better quality in the final products. Moreover, textural properties showed that the effect of BSG on hardness and adhesiveness was significantly greater than QSG and CSG at the same concentration. Based on obtained result, 0.3% concentration of added BSG had a much greater effects on the whipped cream properties than those of mixes with QSG and CSG.

  4. Flavor-Enhanced Modulation of Cerebral Blood Flow during Gum Chewing.

    Directory of Open Access Journals (Sweden)

    Yoko Hasegawa

    Full Text Available Flavor perception, the integration of taste and odor, is a critical factor in eating behavior. It remains unclear how such sensory signals influence the human brain systems that execute the eating behavior.WE TESTED CEREBRAL BLOOD FLOW (CBF IN THE FRONTAL LOBES BILATERALLY WHILE SUBJECTS CHEWED THREE TYPES OF GUM WITH DIFFERENT COMBINATIONS OF TASTE AND ODOR: no taste/no odor gum (C-gum, sweet taste/no odor gum (T-gum, and sweet taste/lemon odor gum (TO-gum. Simultaneous recordings of transcranial Doppler ultrasound (TCD and near infrared spectrometer (NIRS were used to measure CBF during gum chewing in 25 healthy volunteers. Bilateral masseter muscle activity was also monitored.We found that subjects could discriminate the type of gum without prior information. Subjects rated the TO-gum as the most flavorful gum and the C-gum as the least flavorful. Analysis of masseter muscle activity indicated that masticatory motor output during gum chewing was not affected by taste and odor. The TCD/NIRS measurements revealed significantly higher hemodynamic signals when subjects chewed the TO-gum compared to when they chewed the C-gum and T-gum.These data suggest that taste and odor can influence brain activation during chewing in sensory, cognitive, and motivational processes rather than in motor control.

  5. Graft [partially carboxymethylated guar gum-g-poly N-(hydroxymethyl) acrylamide] copolymer: from synthesis to applications.

    Science.gov (United States)

    Pandey, Vijay Shankar; Verma, Shiv Kumar; Behari, Kunj

    2014-09-22

    Graft copolymer of N-(hydroxymethyl) acrylamide with carboxymethylated guar gum was synthesized and the reaction conditions were optimized for better yield using potassium peroxymonosulfate and thiourea as a redox initiator. The optimum reaction conditions for grafting have also been determined by studying the effect of N-(hydroxymethyl) acrylamide, hydrogen ion, peroxymonosulphate, thiourea concentration and carboxymethylated guar gum along with time and temperature. Experimental results show that maximum grafting has been obtained at 1.4 g dm(-3) concentration of carboxymethylated guar gum and 16×10(-2) mol dm(-3) concentration of N-(hydroxymethyl) acrylamide. It has been observed that grafting ratio, add on, conversion, efficiency and rate of grafting increase up to 6.0×10(-3) mol dm(-3) of hydrogen ion, 2.4×10(-3) mol dm(-3) of thiourea, 14×10(-3) mol dm(-3) of peroxymonosulphate and 35°C of temperature. Grafted copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling, flocculating, and metal ion uptake properties of partially carboxymethylated guar gum-g-N-(hydroxymethyl) acrylamide have been determined.

  6. Chew on this: No support for facilitating effects of gum on spatial task performance.

    Science.gov (United States)

    Nader, Ingo W; Gittler, Georg; Waldherr, Karin; Pietschnig, Jakob

    2010-09-01

    To determine whether chewing of gum facilitates spatial task performance in healthy participants, two behavioral experiments were performed. In the first experiment, spatial task performance of 349 men and women preceding and after treatment administration (saccharated chewing gum, sugar-free chewing gum, no chewing gum) was assessed using effect modeling by means of Item Response Theory. In the second experiment, another 100 participants were either administered sugar-free chewing gum or no chewing gum during spatial task performance. Effects of gum in the second study were assessed by standard means of data analysis. Results indicated no significant effects of either chewing gum or sugar on spatial task performance in either experiment. Our findings are consistent with recent studies investigating the influences of chewing gum on various memory functions, extending them by another measure of cognitive ability. Thus, further doubt is cast on enhancing effects of chewing gum on cognitive task performance. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. An association between temporomandibular disorder and gum chewing.

    Science.gov (United States)

    Correia, Diana; Real Dias, Maria Carlos; Castanho Moacho, Antonio; Crispim, Pedro; Luis, Henrique; Oliveira, Miguel; Carames, Joao

    2014-01-01

    This single center, randomized, small study sought to investigate the prevalence and frequency of chewing gum consumption, and whether there is a relationship between these factors and the presence of symptoms associated with temporomandibular disorder (TMD). Subjects were divided into 7 groups based on their parafunctional oral habits. Of these, subjects who chewed gum were divided into 5 subgroups (A-E) based on their gum chewing habits. Group A chewed gum 3 hours at a time (n = 8); the frequency of gum chewing in Groups A-D was once a week. Group E subjects chewed gum 1-3 times/week for at least 1 hour each occurrence (n = 2). Sixty-three percent of the subjects in Group D reported TMD symptoms of arthralgia and myofascial pain. Thirty-three percent of the subjects in Group C showed symptoms of arthralgia. Eighty-three percent of the subjects in Group A and 27% in Group B reported myofascial pain. All subjects in Group E reported masseter hypertrophy. The remaining 2 groups were Group F, subjects that didn't chew gum but had other parafunctional oral habits (n = 2), and Group G, subjects who didn't have parafunctional oral habits (n = 12).

  8. The rheological properties of tara gum (Caesalpinia spinosa).

    Science.gov (United States)

    Wu, Yanbei; Ding, Wei; Jia, Lirong; He, Qiang

    2015-02-01

    The rheological properties of tara gum, as affected by concentration, temperature, pH and the presence of salts and sucrose, were investigated by using steady and dynamic shear measurements and atomic force microscope observation. Tara gum exhibited non-Newtonian, pseudoplastic behaviour without thixotropy at tested concentrations (0.2-1.0%, w/v). Salts (CaCl2 and NaCl) led to a viscosity reduction, which was more sensitive to Ca(2+) than to Na(+). The gum had stable viscosity over a wide pH range (pH 3-11), and the influence of sucrose was concentration dependent. Increasing temperature from 20°C to 80°C decreased the gum viscosity. Frequency sweeps indicated that tara gum (1.0% w/v) behaved as a liquid at low frequency, and acted more like a gel at high frequency. With the decrease of concentration, tara gum may show a viscous property rather than an elastic one. These results are potentially useful for the application of tara gum in food processing.

  9. Carboxymethylation of Cassia angustifolia seed gum: synthesis and rheological study.

    Science.gov (United States)

    Rajput, Gaurav; Pandey, I P; Joshi, Gyanesh

    2015-03-06

    The seeds of Cassia angustifolia are a rich source of galactomannan gum. The seed gums possess a wide variety of industrial applications. To utilize C. angustifolia seed gum for broader industrial applications, the carboxymethyl-Cassia angustifolia seed gum (CM-CAG) was synthesized. The gum was etherified with sodium monochloroacetate (SMCA) in a methanol-water system in presence of alkali (NaOH) at different reaction conditions. The variables studied includes alkali concentration, SMCA concentration, methanol:water ratio, liquor:gum ratio, reaction temperature and time. The extent of carboxymethylation was determined as degree of substitution (DS). The optimum conditions for preparing CM-CAG (DS=0.474) comprised 0.100 mol of NaOH, 0.05 mol of SMCA, 80% of methanol:water ratio (as % methanol) and liquor:gum ratio (v/w) of 10:1 at 75 °C for 60 min using 0.03 mol (as AGU) of CAG. Rheological studies showed CM-CAG to exhibit non-Newtonian pseudoplastic behaviour, relatively high viscosity, cold water solubility and solution stability. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Bactericidal activity of Pistacia lentiscus mastic gum against Helicobacter pylori.

    Science.gov (United States)

    Marone, P; Bono, L; Leone, E; Bona, S; Carretto, E; Perversi, L

    2001-12-01

    In this study we evaluated the antibacterial activity of mastic gum, a resin obtained from the Pistacia lentiscus tree, against clinical isolates of Helicobacter pylori. The minimal bactericidal concentrations (MBCs) were obtained by a microdilution assay. Mastic gum killed 50% of the strains tested at a concentration of 125 microg/ml and 90% at a concentration of 500 microg/ml. The influence of sub-MBCs of mastic gum on the morphologies of H. pylori was evaluated by transmission electron microscopy. The lentiscus resin induced blebbing, morphological abnormalities and cellular fragmentation in H. pylori cells.

  11. Hydrophobic derivatives of guar gum hydrolyzate and gum Arabic as matrices for microencapsulation of mint oil.

    Science.gov (United States)

    Sarkar, Shatabhisa; Gupta, Sumit; Variyar, Prasad S; Sharma, Arun; Singhal, Rekha S

    2013-06-05

    Guar gum hydrolyzate (GGH) modified with n-octenyl succinic anhydride (OSA) and oleic acid having induced hydrophobicity was evaluated for encapsulation of mint oil and compared with gum Arabic (GA) and GA-OSA as wall material. Spray dried microcapsules prepared with these wall materials were evaluated for qualitative changes by principal component analysis and for percent retention of mint oil during 8-week storage. Results revealed that microcapsules with GGH-OSA and GGH-oleate showed slightly lower retention of mint oil as compared to GA. GA-OSA microcapsules showed better retention of mint oil than GA itself, as observed from the t1/2, the time required for the mint oil to come down to 50% of its original content. The t1/2 of mint oil in microcapsules of GA, GGH-oleate, GGH-OSA and GA-OSA was 26.12, 23.50, 24.11 and 29.67 weeks, respectively. The results suggested that GGH-OSA has the potential to replace gum Arabic for encapsulation of mint oil. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. In vitro tooth whitening effect of two medicated chewing gums compared to a whitening gum and saliva

    Directory of Open Access Journals (Sweden)

    Saroea Geoffrey

    2008-08-01

    Full Text Available Abstract Background Extrinsic staining of teeth may result from the deposition of a variety of pigments into or onto the tooth surface, which originate mainly from diet or from tobacco use. More recently, clinical studies have demonstrated the efficacy of some chewing gums in removing extrinsic tooth staining. The aim of this study was to assess the effectiveness of two nicotine medicated chewing gums (A and B on stain removal in an in vitro experiment, when compared with a confectionary whitening chewing gum (C and human saliva (D. Methods Bovine incisors were stained by alternating air exposure and immersion in a broth containing natural pigments such as coffee, tea and oral microorganisms for 10 days. Stained enamel samples were exposed to saliva alone or to the test chewing gums under conditions simulating human mastication. The coloration change of the enamel samples was measured using a spectrophotometer. Measurements were obtained for each specimen (average of three absorbances using the L*a*b scale: lightness (L*, red-green (a and yellow-blue (b. Results Medicated chewing gums (A and B removed a greater amount of visible extrinsic stain, while the confectionary chewing gum with a whitening claim (C had a milder whitening effect as evaluated by quantitative and qualitative assessment. Conclusion The tested Nicotine Replacement Therapy (NRT chewing gums were more effective in the removal of the extrinsic tooth stain. This visible improvement in tooth whitening appearance could strengthen the smokers' motivation to quit smoking.

  13. In vitro release characteristics of matrix tablets: Study of Karaya gum and Guar gum as release modulators

    Directory of Open Access Journals (Sweden)

    Senapati M

    2006-01-01

    Full Text Available Matrix tablets of phenylpropanolamine were fabricated using karaya gum and guar gum, alone or in combination with other excipients. The tablets were evaluated for physical characteristics like hardness, weight variation, friability, swelling index and drug content. In vitro release of drug was performed in 0.1N HCl (pH 1.2 for 2 h and the rest of dissolution in phosphate buffer (pH 6.8. The effect of water-soluble (lactose and water-insoluble (dicalcium phosphate excipients on drug release was evaluated. All the physical characteristics of the fabricated tablets were within acceptable limits. The tablets with karaya gum exhibited greater swelling indices than those with guar gum. All the batches provided drug release over a period of 6 h. The level of matrix former in the tablets affects drug release. Incorporation of lactose or dicalcium phosphate influenced drug release, but at lower polymer levels only. A combination of karaya gum and guar gum exhibited more sustained release than individual gum.

  14. Contracture deformity

    Science.gov (United States)

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  15. Physicochemical and functional parameters of Cochlospermum vitifolium (bototo gum exudate

    Directory of Open Access Journals (Sweden)

    Maritza Coromoto Martínez

    2016-12-01

    Full Text Available The physicochemical parameters of Cochlospermum vitifolium they were evaluated and were linked to certain functional properties of industrial interest. The physicochemical parameters were determined by the classic methodology used for carbohydrates and the functional properties, as reported in the literature. The results obtained showed that the gum object of this study is low soluble in water, which corresponds with relatively high values of swelling indexes and water absorption capacity. Also, the intrinsic viscosity of the C. vitifolium exudate was related to a high molar mass, in the order of 106. Its emulsifying capacity is high, which is attributed to hydrophobic groups present in its structure. The gum gels at a minimum concentration, similar to that of the gum karaya (4.5%, but the gel that forms agglomerates, it is not uniform. The C. vitifolium gum exhibits important physicochemical and functional parameters which could serve as a criterion for testing its use in various industries.

  16. Ask a Periodontist (Frequently Asked Questions about Gum Disease)

    Science.gov (United States)

    ... in adolescents. However, children should still learn the importance of keeping their teeth and gums healthy to ... periodontist. Many periodontists are willing to set up financing options, such as a payment plan. They also ...

  17. Marijuana May Make Your Gums Go to Pot

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_166148.html Marijuana May Make Your Gums Go to Pot People ... but it was surprising to see that recreational cannabis [pot] users may also be at risk," said ...

  18. 21 CFR 172.780 - Acacia (gum arabic).

    Science.gov (United States)

    2010-04-01

    ... Other Specific Usage Additives § 172.780 Acacia (gum arabic). The food additive may be safely used in...). Copies may be examined at the Center for Food Safety and Applied Nutrition's Library, Food and...

  19. Modification of Portland cement mortars with cactus gum

    OpenAIRE

    Hernandez-Zaragoza, Juan-Bosco; Caballero-Badillo, Carlos-Eduardo; Rosas-Juarez, Arnulfo; Lopez-Lara, Teresa; Hinojosa-Torres, Jaime; Castano, Victor-Manuel

    2007-01-01

    ????????, ?? ?????????? ??????? ?? ?????? ????????-???????, ??? ???????????????? ? ????????? ???????????, ???????????? ?????????? ?????????? ??????, ????????? ? ????????? ?????????????? ???????. ???????? ?????????? ???????? ??? ????????? ???????? ??? ????????? ?? 65 %, ????????? ?? ???????????? ?????????. Portland cement-based mortars of the standard type used for modern constructions, were modified by adding liophilized cactus gum, extracted froman indigenous Mexican cactus. The results show...

  20. Development of sodium alginate and konkoli gum- grafted ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-05-02

    May 2, 2008 ... gum (KG), temperature and reaction time have remarkable influence on the percentage graft ... horticulture, gel actuators, water blocking tapes, medicine ... screen to obtain fine powder and packaged in a polyethylene bag.

  1. Evaluation of CDs and chewing gum in teaching dental anatomy.

    Science.gov (United States)

    Allen, Kenneth L; Galvis, Diana; Katz, Ralph V

    2006-01-01

    The purposes of this pilot study were: 1. to compare two methods of teaching dental anatomy-CD + lab vs. standard lecture + lab; and 2. to determine whether actively chewing gum during lecture, lab and studying would have an effect on learning. Only the written examination average scores for the gum vs. no gum chewing groups showed differences that appear to be educationally meaningful, though not statistically significant because of the limited number of subjects in this pilot study. This pilot study suggests that: 1. the cost-effective method of using a self-study CD is as educationally effective as a standard lecture; 2. gum chewing resulted in higher scores in the written examination; and 3. future, full-sized studies should be conducted to confirm these findings.

  2. Phytase application in chewing gum - A technical assessment

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.

    2016-01-01

    Phytase catalysis has been shown to improve iron absorption by dephosphorylation of the potent iron chelator, phytic acid, found in high amounts in cereals. Recently, the World Health Organization evaluated the phytase from Aspergillus niger as safe for use in human food. The phytase may work...... either prior to ingestion, i.e. in the food, or post ingestion, i.e. in the human gastrointestinal tract. We have assessed the technical aspects of formulation and release of phytase added to chewing gum as a delivery vehicle. Phytases from Aspergillus niger and Escherichia coli incorporated into chewing...... gum were released quantitatively upon chewing and retained phytase activity (50-80% of the enzyme activity added was released within 10 minutes). Initial evaluations of phytase chewing gum shelf life showed good stability after 48 days of storage of the chewing gum at ambient conditions....

  3. Preparation and evaluation of soft gellan gum gel containing paracetamol

    Directory of Open Access Journals (Sweden)

    Gohel M

    2009-01-01

    Full Text Available The objective of this study was to develop soft paracetamol gel using gellan gum as a gelling agent and sodium citrate as a source of cation. Different batches were prepared using three different concentrations of gellan gum (0.1, 0.3, and 0.5%, each with two different sodium citrate concentrations (0.3 and 0.5%. The consistency of the paracetamol gel was dependent on the concentration of gellan gum, sodium citrate and co-solute. The results of dissolution study of soft gel containing 0.3% gellan gum and 0.3% sodium citrate revealed that paracetamol was completely released in 30 min. Polyethylene glycol 400 worked as a solubilizer for paracetamol. All the gels possessed acceptable sensory characteristics when evaluated by human volunteers. Short term stability study carried out for four weeks at different temperatures revealed no considerable changes in performance characteristics of developed optimized formulation.

  4. Modification of Portland cement mortars with cactus gum

    OpenAIRE

    Hernandez-Zaragoza, Juan-Bosco; Caballero-Badillo, Carlos-Eduardo; Rosas-Juarez, Arnulfo; Lopez-Lara, Teresa; Hinojosa-Torres, Jaime; Castano, Victor-Manuel

    2007-01-01

    ????????, ?? ?????????? ??????? ?? ?????? ????????-???????, ??? ???????????????? ? ????????? ???????????, ???????????? ?????????? ?????????? ??????, ????????? ? ????????? ?????????????? ???????. ???????? ?????????? ???????? ??? ????????? ???????? ??? ????????? ?? 65 %, ????????? ?? ???????????? ?????????. Portland cement-based mortars of the standard type used for modern constructions, were modified by adding liophilized cactus gum, extracted froman indigenous Mexican cactus. The results show...

  5. OPTIMASI KONSENTRASI GUM ARAB DAN EKSTRAK REMPAH-REMPAH PADA EDIBLE COATING BERAS CEPAT TANAK DENGAN INDEKS GLISEMIK RENDAH Optimation of Gum Arabic and Spices Extract Concentration to Edible Coating of Low Glycemic Index Quick Cooking Rice

    Directory of Open Access Journals (Sweden)

    Ch. Lilis Suryani

    2012-05-01

    Full Text Available Quick cooking rice is pragelatinised rice that required short cooking time. However, the Glycemic Index (GI of quick cooking rice was quite high, so that less suitable for diabetes mellitus patients. Spices extract (ginger, cinnamon, clove had ability to reduce GI because of their phenolic content. The purposes of this research was to produce quick cooking rice coated with gum arabic that enriched with spices extracts (BCTER, so had low glycemic index. Quick cooking rice was coated with gum arabic (20, 30 and 40 % and enriched with spices extracts (15, 20 and 15 %. The parameters that was analysis were moisture and phenolic content, phenol retention, texture, acceptability and glycemic index. The research showed that acceptable BCTER was produce by coated with 40 % gum arabic that enriched by 20 % spice extracts concentration. Cooked  BCTER had moisture content 53.82 %, phenol content 50.00 ppm, texture with resistance to force 6.98 N and deformation 32.45 %. Phenol retention of BCTER was 48.96 %, and the glycemic index (GI was 45.34. ABSTRAK Beras cepat tanak adalah beras yang telah mengalami proses pragelatinisasi sehingga memerlukan waktu pemasakan yang lebih singkat. Namun beras cepat tanak memiliki Indeks Glikemik (IG yang cukup tinggi, sehingga kurang cocok untuk penderita diabetes mellitus. Ekstrak rempah-rempah (jahe, kayu manis, cengkeh diketahui memiliki kemampuan menurunkan IG karena mengandung senyawa fenolik. Tujuan penelitian ini adalah menghasilkan beras cepat tanak yang mempunyai IG rendah dengan pelapisan edible film gum arab yang diperkaya ekstrak rempah-rempah (BCTER. Beras cepat tanak dilapisi dengan larutan edible coating gum arab (20, 30 dan 40 % b/v yang diperkaya dengan ekstrak rempah-rempah (15, 20 dan 15 % b/v. Parameter yang diuji adalah kadar air, fenol, retensi fenol, tekstur, uji tingkat kesukaan dan penentuan IG BCTER. Hasil penelitian menunjukkan bahwa BCTER yang terbaik adalah beras dengan edible coating gum

  6. Formulation and characterization of rifabutin loaded floating gellan gum beads

    OpenAIRE

    2011-01-01

    Rifabutin loaded floating gellan gum beads were prepared by Ca++ induced ionotropic gelation in acidic medium by drop wise addition of gellan gum dispersion containing drug and gas-generating agent. The prepared beads were evaluated for in vitro characterization and in vivo Helicobacter pylori clearance efficiency following repeated oral administration to H. pylori infected albino rats. Live cell staining of stomach homogenates of H. pylori infected animals treated with rifabutin showed prono...

  7. [Inspection of undesignated food color in imported chewing gum].

    Science.gov (United States)

    Kawasaki, Y; Ishiwata, H; Yamada, T

    1999-01-01

    An unknown color in chewing gum imported from Canada was determined. The color was identified by TLC and HPLC as the trisodium salt of 3-hydroxy-4[(4-sulfopheny)azo]-2,7-naphthalenedisulfonic acid (RS-SA), one of the subsidiary colors of sunset yellow FCF. The concentration of RS-SA in sunset yellow FCF used in the chewing gum was 4.3%

  8. Evaluation of carboxymethyl moringa gum as nanometric carrier.

    Science.gov (United States)

    Rimpy; Abhishek; Ahuja, Munish

    2017-10-15

    In the present study, carboxymethylation of Moringa oleifera gum was carried out by reacting with monochloroacetic acid. Modified gum was characterised employing Fourier-transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy, and Rheology study. The carboxymethyl modification of moringa gum was found to increase its degree of crystallinity, reduce viscosity and swelling, increase the surface roughness and render its more anionic. The interaction between carboxymethyl moringa gum and chitosan was optimised by 2-factor, 3-level central composite experimental design to prepare polyelectrolyte nanoparticle using ofloxacin, as a model drug. The optimal calculated parameters were found to be carboxymethyl moringa gum- 0.016% (w/v), chitosan- 0.012% (w/v) which provided polyelectrolyte nanoparticle of average particle size 231nm and zeta potential 28mV. Carboxymethyl moringa gum-chitosan polyelectrolyte nanoparticles show sustained in vitro release of ofloxacin upto 6h which followed first order kinetics with mechanism of release being erosion of polymer matrix. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. The effect of ingestion of guar gum on ileostomy effluent.

    Science.gov (United States)

    Higham, S E; Read, N W

    1992-01-01

    Randomized, paired studies were carried out on five healthy volunteers equipped with terminal ileostomies to investigate the effect of incorporating 15 g of the viscous polysaccharide guar gum in the normal diet on the volume, weight, composition and physical properties of ileostomy effluent. Subjects ate an identical diet during two 5 d study periods, which were separated by 2 d. Outputs of fat, protein, sodium, potassium, dry weight and water were all increased during guar gum administration, but outputs of carbohydrate, calcium and phosphorus were not significantly altered. Mouth-to-stoma transit was not significantly affected and, surprisingly, the viscosity of the ileostomy effluent was reduced by guar gum. These results show that it is not always possible to predict what will happen to small intestinal function when guar gum is added to the diet from experiments carried out when guar gum is administered alone or with glucose. While our findings show that guar gum will reduce fat absorption, the mechanisms involved are more sophisticated than hitherto envisaged.

  10. GumTree—An integrated scientific experiment environment

    Science.gov (United States)

    Lam, Tony; Hauser, Nick; Götz, Andy; Hathaway, Paul; Franceschini, Fredi; Rayner, Hugh; Zhang, Lidia

    2006-11-01

    GumTree is an open source and multi-platform graphical user interface for performing neutron scattering and X-ray experiments. It handles the complete experiment life cycle from instrument calibration, data acquisition, and real time data analysis to results publication. The aim of the GumTree Project is to create a highly Integrated Scientific Experiment Environment (ISEE), allowing interconnectivity and data sharing between different distributed components such as motors, detectors, user proposal database and data analysis server. GumTree is being adapted to several instrument control server systems such as TANGO, EPICS and SICS, providing an easy-to-use front-end for users and simple-to-extend model for software developers. The design of GumTree is aimed to be reusable and configurable for any scientific instrument. GumTree will be adapted to six neutron beam instruments for the OPAL reactor at ANSTO. Other European institutes including ESRF, ILL and PSI have shown interest in using GumTree as their workbench for instrument control and data analysis.

  11. GumTree-An integrated scientific experiment environment

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Tony [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia)]. E-mail: Tony.Lam@ansto.gov.au; Hauser, Nick [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia); Goetz, Andy [ESRF, 6, rue Jules Horowitz, Grenoble 38043 (France); Hathaway, Paul [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia); Franceschini, Fredi [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia); Rayner, Hugh [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia); Zhang, Lidia [Bragg Institute, ANSTO, Private Mailbag 1, Menai 2234, NSW (Australia)

    2006-11-15

    GumTree is an open source and multi-platform graphical user interface for performing neutron scattering and X-ray experiments. It handles the complete experiment life cycle from instrument calibration, data acquisition, and real time data analysis to results publication. The aim of the GumTree Project is to create a highly Integrated Scientific Experiment Environment (ISEE), allowing interconnectivity and data sharing between different distributed components such as motors, detectors, user proposal database and data analysis server. GumTree is being adapted to several instrument control server systems such as TANGO, EPICS and SICS, providing an easy-to-use front-end for users and simple-to-extend model for software developers. The design of GumTree is aimed to be reusable and configurable for any scientific instrument. GumTree will be adapted to six neutron beam instruments for the OPAL reactor at ANSTO. Other European institutes including ESRF, ILL and PSI have shown interest in using GumTree as their workbench for instrument control and data analysis.

  12. Oxidized Xanthan Gum and Chitosan as Natural Adhesives for Cork

    Directory of Open Access Journals (Sweden)

    Diana Paiva

    2016-07-01

    Full Text Available Natural cork stopper manufacturing produces a significant amount of cork waste, which is granulated and combined with synthetic glues for use in a wide range of applications. There is a high demand for using biosourced polymers in these composite materials. In this study, xanthan gum (XG and chitosan (CS were investigated as possible natural binders for cork. Xanthan gum was oxidized at two different aldehyde contents as a strategy to improve its water resistance. This modification was studied in detail by 1H and 13C nuclear magnetic resonance (NMR, and the degree of oxidation was determined by the hydroxylamine hydrochloride titration method. The performance of the adhesives was studied by tensile tests and total soluble matter (TSM determinations. Xanthan gum showed no water resistance, contrary to oxidized xanthan gum and chitosan. It is hypothesized that the good performance of oxidized xanthan gum is due to the reaction of aldehyde groups—formed in the oxidation process—with hydroxyl groups on the cork surface during the high temperature drying. Combining oxidized xanthan gum with chitosan did not yield significant improvements.

  13. Effect of guar and xanthan gums on functional properties of mango (Mangifera indica) kernel starch.

    Science.gov (United States)

    Nawab, Anjum; Alam, Feroz; Haq, Muhammad Abdul; Hasnain, Abid

    2016-12-01

    The effects of different concentrations of guar and xanthan gums on functional properties of mango kernel starch (MKS) were studied. Both guar and xanthan gum enhanced the water absorption of MKS. The addition of xanthan gum appeared to reduce the SP (swelling power) and solubility at higher temperatures while guar gum significantly enhanced the SP as well as solubility of MKS. The addition of both gums produced a reinforcing effect on peak viscosity of MKS as compared to control. Pasting temperature of MKS was higher than that of starch modified by gums indicating ease of gelatinization. Guar gum played an accelerative effect on setback but xanthan gum delayed the setback phenomenon during the cooling of the starch paste. Both gums were found to be effective in reducing the syneresis while gel firmness was markedly improved. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Application of cashew tree gum on the production and stability of spray-dried fish oil.

    Science.gov (United States)

    Botrel, Diego Alvarenga; Borges, Soraia Vilela; Fernandes, Regiane Victória de Barros; Antoniassi, Rosemar; de Faria-Machado, Adelia Ferreira; Feitosa, Judith Pessoa de Andrade; de Paula, Regina Celia Monteiro

    2017-04-15

    Evaluation of cashew gum compared to conventional materials was conducted regarding properties and oxidative stability of spray-dried fish oil. Emulsions produced with cashew gum showed lower viscosity when compared to Arabic gum. The particle size was larger (29.9μm) when cashew gum was used, and the encapsulation efficiency reached 76%, similar to that of modified starch but higher than that for Arabic gum (60%). The oxidation process for the surface oil was conducted and a relative lower formation of oxidation compounds was observed for the cashew gum treatment. GAB model was chosen to describe the moisture adsorption isotherm behaviours. Microparticles produced using Arabic and cashew gums showed greater water adsorption when exposed to higher relative humidities. Microparticles produced using cashew gum were more hygroscopic however encapsulation efficiency were higher and surface oil oxidation were less pronounced. Cashew gum can be further explored as an encapuslant material for spray drying processes.

  15. 冷挤压摩擦对金属变形流动和模具受力的影响%On Influence of Cold Extrusion Friction to Metal Deformation Flow and Die Stress

    Institute of Scientific and Technical Information of China (English)

    尹甜甜; 李辉

    2015-01-01

    With using the Deform-3D software, it analyzes the mechanism of backward extrusion metal deformation flow under different friction states, and explores the pressure distribution and its maximum value of die inwall and the relationship between die inwall maximum pressure and terrace die specific pressure.%采用Deform-3D软件对不同摩擦状况下反挤压金属变形流动的机理进行分析,探讨了不同摩擦状况下,凹模内壁压力分布及其最大值,凹模内壁压力最大值与凸模单位压力的关系。

  16. Pathogenicity of EPS-deficient mutants (gumB-, gumD and gumE - ) of Xanthomonas campestris pv. campestris

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Three extracellular polysaccharide (EPS) -deficient mutants of the pathogen Xanthomonas campestris pv. campestris, gumB - , gumD - and gumE- were constructed by Tn5 gusA5 mutagenesis in this study. The results of pathogenicity bioassay showed that three mutants had the obviously decreased pathogenicity on radish ( Raphanus sativus L. ) leaves. Because dead body of the bacteria still caused symptoms, it seemed that some unknown factors on the bac terial cell surface might play certain roles in the pathogenicity of the pathogen. The extracted raw EPS could lead to the chlorotic symptom on radish leaves, and its virulence was increased with the increase of EPS dosage, which suggested that EPS was a main component that caused the danage on radish leaves.

  17. Analyses of deformation and thermal-hydraulics within a wire-wrapped fuel subassembly in a liquid metal fast reactor by the coupled code system

    Energy Technology Data Exchange (ETDEWEB)

    Uwaba, Tomoyuki, E-mail: uwaba.tomoyuki@jaea.go.jp; Ohshima, Hiroyuki; Ito, Masahiro

    2017-06-15

    Highlights: • The coupled computational code system allowed for mechanical and thermal-hydraulic analyses in a fast reactor fuel subassembly. • In this system interactive calculations between flow area deformations and coolant temperature changes are repeated to their convergence state. • Effects on bundle-duct interaction on coolant temperature distributions were investigated by using the code system. - Abstract: The coupled numerical analysis of mechanical and thermal-hydraulic behaviors was performed for a wire-wrapped fuel pin bundle subassembly irradiated in a fast reactor. For the analysis, the fuel pin bundle deformation analysis code BAMBOO and the thermal-hydraulic analysis code ASFRE exchanged the deformation and temperature analysis results through the iterative calculations to attain convergence corresponding to the static balance between deformation and temperature. The analysis by the coupled code system showed that the radial distribution of coolant temperature in the subassembly tended to flatten as a result of the fuel pin bundle deformation governed by cladding void swelling and irradiation creep. Such flattening of temperature distribution was slightly observed as a result of fuel pin bowings due to the cladding-wire interaction even when no bundle-duct interaction occurred. The effect of the spacer wire-pitch on deformation and thermal-hydraulics was also investigated in this study.

  18. Formulation development and evaluation of novel oral jellies of carbamazepine using pectin, guar gum, and gellan gum

    Directory of Open Access Journals (Sweden)

    Katakam Prakash

    2014-01-01

    Full Text Available Medicated jelly formulations are more suitable for pediatric, geriatric and dysphagic patients, which offer rapid dissolution and absorption of drugs thereby early onset of action. The aim was to develop and evaluate oral jelly formulations of carbamazepine (CBZ. Carbamazepine oral jellies were prepared to employ pectin, guar gum and gellan gum alone and pectin-guar gum combination. Preformulation studies, organoleptic, physical characteristics, drug content, pH, spreadability, rheological properties, syneresis, taste masking, in vitro dissolution testing, drug release kinetics and stability studies were conducted. The Fourier transform infrared and differential scanning calorimeter studies showed that there was no interaction between drug and excipients. The pH of all the formulations was found between pH 6.37 ± 0.03 and 6.83 ± 0.04. The concentration of gelling agents influenced the spreadability. Syneresis was observed in jellies made from guar gum alone, whereas those made from pectin and guar gum it was absent. The optimized formulations (F3, F11 and F15 masked the bitter taste of CBZ and demonstrated acceptable flavor and mouth feel. All formulations showed more than 50% drug release in 15 min except those made of gellan gum alone. The formulations F3, F11 and F15, were found stable for 90 days as per International Conference on Harmonization stability protocol. Carbamazepine jellies made from pectin (F3, 1.2%, gellan gum (F11, 1.5% and pectin-guar gum (F15, 1:0.4% were found more successful and could be employed to improve the palatability and acceptability by pediatric, geriatric and dysphagic patients. The jellies could be useful to overcome the problems of poorly soluble CBZ.

  19. Review on compressive deformation of bulk metallic glasses%块体非晶合金压缩变形研究进展

    Institute of Scientific and Technical Information of China (English)

    李明; 刘新才; 潘晶; 鲁贻虎

    2014-01-01

    In this paper,the compressive deformation behavior,samples surfaces and fracture microstructure characteristics have been reviewed at different temperatures and strain rates for bulk metallic glasses (BMGs). BMGs behave like inhomogeneous brittle fracture,non-Newtonian fluid and Newtonian fluid mode respectively at reduced compressing temperature tr=T/Tg ranging of 77 K/Tg≤trdeformation and heat.With tr increas-ing,fracture microstructure characteristics changed from complex and inhomogeneous vein-like pattern to hom-ogeneous one,then to droplets,or lava-flow pattern.In addition,Ni60 Pd20 P17 B3 BMG and Ti40 Zr25 Ni3 Cu12 Be20 BMG behaved like non-Newtonian fluid mode during compressing at tr=0.127-0.503.Finally,this paper also discussed the phenomenon of nanocrystallization during the compression deformation.%在约化压缩变形温度tr=T/Tg 为77 K/T g≤t r

  20. Solar drying of uruguayan red gum

    Directory of Open Access Journals (Sweden)

    Andrés Ono

    2011-04-01

    Full Text Available he use of solar energy as an alternative to non-renewable energy sources has been widely researched in the last decades. Compared to air drying, solar drying kilns can better control the drying process, resulting in a higher quality of the dry wood and lower final wood moisture content values. Investment and running costs for a solar drying kiln are lower than those of a conventional kiln. Moreover, the solar drying process can be advantageous for drying hardwoods which are traditionally considered difficult to dry such as eucalyptus wood of medium and high density (Red gums, known in Spanish as “Eucaliptos colorados”. The solar drying kiln naturally incorporates a daily high relative humidity period that can be similar to a conditioning or steaming step, although at a lower temperature.This results in fewer defects due to the drying process.A pilot scale 2.5 m3 semi-greenhouse type solar wood drying kiln was constructed at LATU (Uruguay Technological Laboratory in Montevideo, Uruguay. The operating conditions and the results from two drying runs are presented. Two species of red gum (Eucalyptus tereticornis Sm., ADD 870 kg/m3, and Eucalyptus camaldulensis Dehnh., ADD 800 kg/m3 were dried from initial average moisture contents (WMC of around 60% down to 10.0% and 12.7% in 108 days and 76 days, respectively. Boards were provided by the Grupo Forestal San Gregorio from trees harvested at Tacuarembo and Paysandu Departments from cattle shelter forests 60 and 70 years old.Mean volume shrinkage was 18% for E. tereticornis, and 16% for E. camaldulensis, and the level of defects was moderate. Residual stresses and moisture content gradients were observed for both species. Final moisture content values were similar compared to those obtained in conventional drying kilns but with longer drying periods and lower operating costs. This would make the solar drying process attractive to small and medium sized forest products industries in a small country

  1. Ultrasound assisted enzymatic depolymerization of aqueous guar gum solution.

    Science.gov (United States)

    Prajapat, Amrutlal L; Subhedar, Preeti B; Gogate, Parag R

    2016-03-01

    The present work investigates the effectiveness of application of low intensity ultrasonic irradiation for the intensification of enzymatic depolymerization of aqueous guar gum solution. The extent of depolymerization of guar gum has been analyzed in terms of intrinsic viscosity reduction. The effect of ultrasonic irradiation on the kinetic and thermodynamic parameters related to the enzyme activity as well as the intrinsic viscosity reduction of guar gum using enzymatic approach has been evaluated. The kinetic rate constant has been found to increase with an increase in the temperature and cellulase loading. It has been observed that application of ultrasound not only enhances the extent of depolymerization but also reduces the time of depolymerization as compared to conventional enzymatic degradation technique. In the presence of cellulase enzyme, the maximum extent of depolymerization of guar gum has been observed at 60 W of ultrasonic rated power and ultrasonic treatment time of 30 min. The effect of ultrasound on the kinetic and thermodynamic parameters as well as the molecular structure of cellulase enzyme was evaluated with the help of the chemical reaction kinetics model and fluorescence spectroscopy. Application of ultrasound resulted in a reduction in the thermodynamic parameters of activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) by 47%, 50%, 65% and 1.97%, respectively. The changes in the chemical structure of guar gum treated using ultrasound assisted enzymatic approach in comparison to the native guar gum were also characterized by FTIR. The results revealed that enzymatic depolymerization of guar gum resulted in a polysaccharide with low degree of polymerization, viscosity and consistency index without any change in the core chemical structure which could make it useful for incorporation in food products.

  2. Haglund's Deformity

    Science.gov (United States)

    ... to follow the surgeon’s instructions for postsurgical care. Prevention To help prevent a recurrence of Haglund’s deformity: wear appropriate shoes; avoid shoes with a rigid heel back use arch supports or orthotic devices perform stretching exercises to prevent the Achilles tendon from tightening ...

  3. A NEW SPECIES OF INVASIVE GALL WASP (HYMENOPTERA: EULOPHIDAE: TETRASTICHINAE) ON BLUE GUM (EUCALYPTUS GLOBULUS) IN CALIFORNIA

    Science.gov (United States)

    The blue gum gall wasp, Selitrichodes globulus La Salle & Gates (Hymenoptera: Eulophidae: Tetrastichinae), is described as an invasive gall inducer on blue gum, Eucalyptus globulus (Myrtaceae), in California....

  4. Microencapsulation of saffron petal anthocyanins with cress seed gum compared with Arabic gum through freeze drying.

    Science.gov (United States)

    Jafari, Seid-Mahdi; Mahdavi-Khazaei, Katayoun; Hemmati-Kakhki, Abbas

    2016-04-20

    In this research, encapsulation efficiency of cress seed gum (CSG) as a native hydrocolloid was compared with Arabic gum (AG) and maltodextrin (dextrose equivalent of 20 (M20), and 7 (M7)) for saffron (Crocus sativus) petal's extract by freeze drying method. Combinations of CSG-M20, AG-M20, and M7-M20 with ratios of 50:50 and M20 alone (100%) were used as wall materials. A mixture of 1:5 (based on dry matter) between core (concentrated anthocyanin extract of saffron petal) and wall materials were freeze dried and stability of encapsulated anthocyanins along with color parameters (a*, b*, L*, C, H° and TCD) of final powders were measured during 10 weeks of storage (at 35°C as an accelerated method). Total anthocyanins were determined through pH differential method every week. Four prepared formulations of encapsulated powders didn't show any significant differences (P>0.01) in terms of total anthocyanin content measured immediately after production and after 10 weeks storage. AG-M20 mixture and M20 alone showed the highest and lowest TCD, respectively. The mixture of CSG-M20 in comparison with AG-M20 and M20 had the same protecting effect (P<0.01) but showed a relatively high TCD (9.33).

  5. Evaluation of release retarding property of gum damar and gum copal in combination with hydroxypropyl methylcellulose.

    Science.gov (United States)

    Fulbandhe, V M; Jobanputra, C R; Wadher, K J; Umekar, M J; Bhoyar, G S

    2012-05-01

    The formulations consisting of a hydrophilic and hydrophobic material were investigated for effect on drug-release pattern from the matrices. Gum damar and gum copal being water-insoluble were used to study the efficiency of combined matrices to sustain the release of drug. Hydroxypropyl methylcellulose K100M and diclofenac sodium were used as the hydrophilic material and model drug, respectively. The influence of concentration of hydroxypropyl methylcellulose on drug release pattern of hydrophobic material was determined. The optimum ratio of drug: polymer was found to be 1:1. The hydrophobic:hydrophilic polymer ratio of 75:25 was found to have a similar release pattern as that of marketed formulation. At this ratio, the initial burst-release that occurred in individual hydrophobic matrices was lowered to a great extent. The release of drug was found to follow Higuchi's equation as the concentration of hydrophobic material was increased. The formulations were compared with marketed formulation Voveran SR, and a correlation was drawn accordingly.

  6. Evaluation of release retarding property of gum damar and gum copal in combination with hydroxypropyl methylcellulose

    Directory of Open Access Journals (Sweden)

    V M Fulbandhe

    2012-01-01

    Full Text Available The formulations consisting of a hydrophilic and hydrophobic material were investigated for effect on drug-release pattern from the matrices. Gum damar and gum copal being water-insoluble were used to study the efficiency of combined matrices to sustain the release of drug. Hydroxypropyl methylcellulose K100M and diclofenac sodium were used as the hydrophilic material and model drug, respectively. The influence of concentration of hydroxypropyl methylcellulose on drug release pattern of hydrophobic material was determined. The optimum ratio of drug: polymer was found to be 1:1. The hydrophobic:hydrophilic polymer ratio of 75:25 was found to have a similar release pattern as that of marketed formulation. At this ratio, the initial burst-release that occurred in individual hydrophobic matrices was lowered to a great extent. The release of drug was found to follow Higuchi′s equation as the concentration of hydrophobic material was increased. The formulations were compared with marketed formulation Voveran SR, and a correlation was drawn accordingly.

  7. STUDIES ON SOME PHYSICOCHEMICAL PROPERTIES OF LEUCAENA LEUCOCEPHALA BARK GUM

    Directory of Open Access Journals (Sweden)

    Vijetha Pendyala

    2010-06-01

    Full Text Available Gum exudates from Leucaena Leucocephala (Family: Fabaceae plants grown all over India were investigated for its physicochemical properties such as pH, swelling capacity and viscosities at different temperatures using standard methods. Leucaena Leucocephala bark gum appeared to be colorless to reddish brown translucent tears. 5 % w/v mucilage has pH of 7.5 at 28°C. The gum is slightly soluble in water and practically insoluble in ethanol, acetone and chloroform. It swells to about 5 times its original weight in water. A 5 %w/v mucilage concentration gave a viscosity value which was unaffected at temperature ranges (28-40°C. At concentrations of 2 and 5 %w/v, the gum exhibited pseudo plastic flow pattern while at 10 %w/v concentration the flow behaviour was thixotropic. The results indicate that the swelling ability of Leucaena Leucocephala (LL bark gum may provide potentials for its use as a disintegrant in tablet formulation, as a hydro gel in modified release dosage forms and the rheological flow properties may also provide potentials for its use as suspending and emulsifying agents owing to its pseudo plastic and thixotropic flow patterns.

  8. RHEOLOGICAL BEHAVIOR OF ERWINIA GUM IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Li-na Zhang; Mei Zhang; Jing-hua Chen; Hideki Iijima; Hiromichi Tsuchiya

    1999-01-01

    Erwinia (E) gum, an extracellular polysaccharide, is composed of fucose, galatose, glucose and glucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and a rotational viscometer. Its weight-average molecular weight Mw and intrinsic viscosity [η] in 0.2 mol/L NaCl aqueous solution were measured by light scattering method at 35℃ and viscometry at 25℃ and found to be 1.06 × 106 g/mol and 1050 mL/g, respectively, and its aggregates in aqueous solution were proved by gel permeation chromatography (GPC). These results indicated that E gum in water has exceedingly high viscosity and exhibits Binham fluid behavior, owing to its aggregation. The viscosity of E gum decreased with increasing temperature, and the turning point appeared at 38℃ for dilute solution and 80℃ for concentrated solution suggesting that the aggregates of E gum in water started to disaggregate under these temperatures. In addition, the aggregates can be disrupted by adding either acid or base. The experimental results indicated that the E gum is a good thickening agent, and its fluid behavior is similar to xanthan.

  9. Self-awareness of "Gum Disease" Among US Adults.

    Science.gov (United States)

    Luo, Huabin; Wu, Bei

    To assess the extent of self-awareness of gum disease among adults in the United States. Data were from the 2009-2012 National Health and Nutrition Examination Survey. The outcome variable is self-awareness of gum disease. Multivariate logistic regression models were used to examine the relationship between self-awareness and clinically diagnosed periodontitis. The analytical sample included 6876 participants. Among those participants (30 years or older) who were classified as having periodontitis, 27% (95% confidence interval [CI], 24.4-29.8) were self-aware of the disease (positive predicted value = 25%). Of those who self-reported having gum disease, 14.1% had a diagnosis of periodontitis (sensitivity = 75%). Older adults were less likely to be aware of gum disease (P self-awareness of gum disease among adults was low. Our study findings suggest that there is a great need to improve oral health knowledge and awareness among the adult population in the United States.

  10. Studies on gum of Moringa oleifera for its emulsifying properties

    Directory of Open Access Journals (Sweden)

    Dibya Sundar Panda

    2014-01-01

    Full Text Available Background: Emulsion has been a form of presenting water insoluble substances for a long period of time. Now a day, it has been a way of presenting various intravenous additives and diagnostic agents in X-ray examinations. Various substances can be used as emulsifying agent, which can be operationally defined as a stabilizer of the droplets formed of the internal phase. Materials and Methods: Gum from Moringa oleifera was evaluated for its emulsifying properties. Castor oil emulsions 30 percent (o/w, containing 2 to 4% Moringa oleifera gum was prepared. Emulsions containing equivalent concentration of acacia were also prepared for comparison. All the emulsions prepared were stored at room temperature and studied for stability at various time intervals for 8 weeks. The prepared emulsions were evaluated for creaming rate, globule size and rate of coalescence. 23 factorial design was chosen to investigate the effects of centrifugation, pH, temperature changes and electrolytes on the creaming rate and globule size. Results: The results of the investigations show that the gum of Moringa oleifera possesses better emulsifying properties as compared to gum acacia. Conclusion: Gum of Moringa oleifera could be used in pharmaceutical and non-pharmaceutical preparation.

  11. Studies on some physicochemical properties of leucaena leucocephala bark gum.

    Science.gov (United States)

    Pendyala, Vijetha; Baburao, Chandu; Chandrasekhar, K B

    2010-04-01

    Gum exudates from Leucaena Leucocephala (Family: Fabaceae) plants grown all over India were investigated for its physicochemical properties such as pH, swelling capacity and viscosities at different temperatures using standard methods. Leucaena Leucocephala bark gum appeared to be colorless to reddish brown translucent tears. 5 % w/v mucilage has pH of 7.5 at 28°C. The gum is slightly soluble in water and practically insoluble in ethanol, acetone and chloroform. It swells to about 5 times its original weight in water. A 5 %w/ v mucilage concentration gave a viscosity value which was unaffected at temperature ranges (28-40°C). At concentrations of 2 and 5 %w/v, the gum exhibited pseudo plastic flow pattern while at 10 %w/v concentration the flow behaviour was thixotropic. The results indicate that the swelling ability of Leucaena Leucocephala (LL) bark gum may provide potentials for its use as a disintegrant in tablet formulation, as a hydro gel in modified release dosage forms and the rheological flow properties may also provide potentials for its use as suspending and emulsifying agents owing to its pseudo plastic and thixotropic flow patterns.

  12. Optimizing the production of welan gum by Alcaligenes facalis NX-3 ...

    African Journals Online (AJOL)

    USER

    2010-02-15

    Feb 15, 2010 ... State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food ... Statistical experiment design and data analysis ... study and optimize process parameters for welan gum ..... effect on welan gum synthesis.

  13. Evaluation of the physico-chemical properties of a new polysaccharide gum from Prosopis africana.

    Science.gov (United States)

    Adikwu, M U; Ezeabasili, S I; Esimone, C O

    2001-01-01

    The gum obtained from the ripe seeds of Prosopis africana was processed to compendial standard for plant gums and characterised. Toxicological studies of the polysaccharide on mice showed the material to be safe. The material hydrates slowly in aqueous media to form a colloidal dispersion. Swelling studies on the gum shows that the gum has a higher swelling capacity than methylcellulose. Rheological studies showed that the material is more viscous than tragacanth gum at equivalent concentrations. Acid hydrolysis and thin layer chromatography of the resulting hydrolysates showed that the gum contains glucose, fructose, galactose and xylose as the monosaccharide components. Microbial tests showed the gum to contain 8.26 x 10(4) viable cells per gram when freshly prepared. Other properties of the gum evaluated includes; melting or charring temperature, optical properties, true density, ash values, element content as well as its reactions with lead subacetate solution and 0.02 M iodine.

  14. Identification of intestinal bacteria responsible for fermentation of gum arabic in pig model.

    Science.gov (United States)

    Kishimoto, Akio; Ushida, Kazunari; Phillips, Glyn O; Ogasawara, Takashi; Sasaki, Yasushi

    2006-09-01

    Acacia spp. produce gum exudates, traditionally called gum arabic or gum acacia, which are widely used in the food industry such as emulsifiers, adhesives, and stabilizers. The traditional gum arabic is highly variable with average molecular weights varying from 300,000-800,000. For this reason a standardized sample was used for the present experiments, based on a specific species of gum arabic (Acacia(sen)SUPER GUMEM2). The literature indicates that gum arabic can be fermented by the intestinal bacteria to short chain fatty acid, particularly propionate. However, the bacteria responsible for the fermentation have not been determined. In this study, we used enrichment culture of pig cecal bacteria from the selected high molecular weight specific gum arabic of (M(W )1.77 x 10(6)). We found Prevotella ruminicola-like bacterium as a predominant bacterium that is most likely to be responsible for fermentation of the gum arabic used to propionate.

  15. Analysis of proteins associated with growth of Bacteroides ovatus on the branched galactomannan guar gum.

    OpenAIRE

    Valentine, P J; Salyers, A A

    1992-01-01

    Bacteroides ovatus, a gram-negative obligate anaerobe from the human colon, can ferment the branched galactomannan guar gum. Previously, three enzymes involved in guar gum breakdown were characterized. The expression of these enzymes appeared to be regulated; i.e., specific activities were higher in extracts from bacteria grown on guar gum than in extracts from bacteria grown on the monosaccharide constituents of guar gum, mannose and galactose. In the present study, we used two-dimensional g...

  16. Deformation Twinning During Nanoindentation of Nanocrystalline Ta

    OpenAIRE

    Wang, Y. M.; Hodge, A. M.; Biener, J.; Hamza, A.V.; Barnes, D E; Liu, Kai; Nieh, T. G.

    2005-01-01

    The deformation mechanism of body-centered cubic (bcc) nanocrystalline tantalum with grain sizes of 10–30 nm is investigated by nanoindentation, scanning electron microscopy and high-resolution transmission electron microscopy. In a deviation from molecular dynamics simulations and existing experimental observations on other bcc nanocrystalline metals, the plastic deformation of nanocrystalline Ta during nanoindentation is controlled by deformation twinning. The observation of multiple twin i...

  17. Effects of xanthan, guar, carrageenan and locust bean gum addition on physical, chemical and sensory properties of meatballs.

    Science.gov (United States)

    Demirci, Zeynep Ozben; Yılmaz, Ismail; Demirci, Ahmet Şukru

    2014-05-01

    This study evaluated the effects of xanthan gum, guar gum, carrageenan and locust bean gum on physical, chemical and sensory properties of meatballs. Meatball samples were produced with three different formulations including of 0.5, 1, and 1.5% each gum addition and gum added samples were compared with the control meatballs. Physical and chemical analyses were carried out on raw and cooked samples separately. Moisture contents of raw samples decreased by addition of gums. There were significant decreases (p gum when compared with control. Ash contents and texture values increased with gum addition to meatballs. Meatball redness decreased with more gum addition in raw and cooked meatball samples, which means that addition of gums resulted in a lighter-coloured product. According to sensory analysis results, locust bean gum added (1%) samples were much preferred by the panelists.

  18. Hybrid modeling of xanthan gum bioproduction in batch bioreactor.

    Science.gov (United States)

    Zabot, Giovani L; Mecca, Jaqueline; Mesomo, Michele; Silva, Marceli F; Prá, Valéria Dal; de Oliveira, Débora; Oliveira, J Vladimir; Castilhos, Fernanda; Treichel, Helen; Mazutti, Marcio A

    2011-10-01

    This work is focused on hybrid modeling of xanthan gum bioproduction process by Xanthomonas campestris pv. mangiferaeindicae. Experiments were carried out to evaluate the effects of stirred speed and superficial gas velocity on the kinetics of cell growth, lactose consumption and xanthan gum production in a batch bioreactor using cheese whey as substrate. A hybrid model was employed to simulate the bio-process making use of an artificial neural network (ANN) as a kinetic parameter estimator for the phenomenological model. The hybrid modeling of the process provided a satisfactory fitting quality of the experimental data, since this approach makes possible the incorporation of the effects of operational variables on model parameters. The applicability of the validated model was investigated, using the model as a process simulator to evaluate the effects of initial cell and lactose concentration in the xanthan gum production.

  19. The role of time on task performance in modifying the effects of gum chewing on attention

    NARCIS (Netherlands)

    Tucha, Lara; Simpson, William

    2011-01-01

    Recent research examined the effects of chewing gum on attention and reported a significant interaction of gum chewing with time. Using a crossover within-subject design, the present study examined the effect of gum chewing on sustained attention in healthy adults over a period of 30 min. The result

  20. Acute and chronic effects of gum chewing on food reinforcement and energy intake.

    Science.gov (United States)

    Swoboda, Christine; Temple, Jennifer L

    2013-04-01

    Although chewing gum has been considered a potential method for reducing energy intake, little empirical data exist to support this idea. The purpose of this study was to test the hypothesis that chewing gum before eating reduces motivation to eat, hunger, and energy intake. In order to test this hypothesis, we conducted two experiments in which participants chewed gum prior to completing a food reinforcement task or before all eating occasions for two of three weeks. In Experiment 1, we found that chewing gum had no influence on the reinforcing value of food, but chewing mint gum reduced liking of and energy intake from fruit. In addition, chewing gum reduced self-reported hunger immediately after gum chewing and after eating compared with the no gum condition. In Experiment 2, gum chewing had no significant effect on total energy intake, but participants consumed fewer meals, consumed more energy per meal, and had a lower nutrient adequacy ratio during the gum chewing weeks. These studies provide no evidence that acute or chronic gum chewing reduces hunger or energy intake. In fact, chewing mint-flavored gum may deter consumption of fruit and reduce diet quality.

  1. TECHNICAL NOTE: The effect of the green additive guar gum on the properties of magnetorheological fluid

    Science.gov (United States)

    Fang, Chen; Zhao, Bin Yuan; Chen, LeSheng; Wu, Qing; Liu, Nan; Hu, Ke Ao

    2005-02-01

    Magnetorheological (MR) fluid containing guar gum was prepared for the first time by ball-milling the guar gum powder together with silicone oil and carbonyl iron powder. By forming a coating layer over the ground carbonyl iron powder, the guar gum improves the sedimentation stability and thixotropy of the MR fluid effectively.

  2. The role of time on task performance in modifying the effects of gum chewing on attention

    NARCIS (Netherlands)

    Tucha, Lara; Simpson, William

    2011-01-01

    Recent research examined the effects of chewing gum on attention and reported a significant interaction of gum chewing with time. Using a crossover within-subject design, the present study examined the effect of gum chewing on sustained attention in healthy adults over a period of 30 min. The result

  3. 76 FR 44811 - Carboxymethyl Guar Gum Sodium Salt and Carboxymethyl-Hydroxypropyl Guar; Exemption From the...

    Science.gov (United States)

    2011-07-27

    ...-0531; FRL-8880-5] Carboxymethyl Guar Gum Sodium Salt and Carboxymethyl- Hydroxypropyl Guar; Exemption... carboxymethyl guar gum sodium salt (CAS Reg. No. 39346-76-4) and carboxymethyl-hydroxypropyl guar (CAS Reg. No... residues of carboxymethyl guar gum sodium salt and carboxymethyl- hydroxypropyl guar. DATES:...

  4. Fluoride and urea chewing gums in an intra-oral experimental caries model

    NARCIS (Netherlands)

    Sjogren, K; Ruben, J; Lingstrom, P; Lundberg, AB; Birkhed, D

    2002-01-01

    The aim of the present investigation was to evaluate the effect of sugar-free chewing gums containing fluoride (F) and urea in an intra-oral experimental caries model. Placebo chewing gums (without any active ingredient) and no gum served as controls. Fifteen subjects participated in a cross-over, s

  5. The Antibacterial Effect of CMCTS-Containing Chewing Gum

    Institute of Scientific and Technical Information of China (English)

    Dagang Miao; Dan Blom; Hongmei Zhao; Xuefei Luan; Tongzhi Chen; Xiaohui Wu; Ning Song

    2009-01-01

    Objective:This paper was designed to confirm the efficacy of chewing carboxymethyl chitosan(CMCTS)-containing gum in suppressing the growth of oral bacteria when compared to a CMCTS-containing mouth rinse.Methods:Fourteen healthy subjects were recruited from among the staff and students of Qingdao University Dentistry Department.Before the experiments saliva was collected from all subjects and bacteria counts determined.For the gum study,the subjects chewed CMCTS-containing gum for 5 rain and then rested for 5 min.When testing the CMCTS mouth rinse,the subjects gargled with 10 mL of solution for 30 s,followed by resting for 9min 30 s.These protocols were repeated five times over a 50 rain period on the same day.Post-experiment saliva samples were then collected at the following times:0,30 and 60 min.Results:Chewing gum containing CMCTS or rinsing with a CMCTS-containing rinse significantly decreased oral bacteria counts.The total bacteria counts,total Streptococci counts,and mutans streptococci counts of saliva from subjects who chewed CMCTS-containing gum were significantly lower than saliva from subjects in the rinse group in all three sampling periods,except in the case of the total bacteria count in the 60 min samples.Conclusion:CMCTS-containing gum chewing has a greater antibac-terial effect than using a CMCTS-containing mouth rinse.The present findings strongly indicate that the application of natural materials such as chitosan and its derivatives is useful for better oral health.

  6. Randomized clinical trial of chewing gum after laparoscopic colorectal resection.

    Science.gov (United States)

    Shum, N F; Choi, H K; Mak, J C K; Foo, D C C; Li, W C; Law, W L

    2016-10-01

    Chewing gum may enhance intestinal motility after surgery. This trial studied whether chewing gum could lead to a further reduction in ileus in patients who had a laparoscopic colorectal resection and followed an enhanced recovery programme. Patients undergoing laparoscopic colorectal resection were randomized to a control or intervention group. Patients in the control group received a standardized recovery programme. Patients in the intervention group were, in addition, given chewing gum three times daily from day 1 until discharge. Primary outcome measures were time to first flatus and first bowel motion. Time to feeling hungry and hospital stay were secondary outcome measures. Forty-one patients were randomized into each group. Thirty-seven patients underwent rectal resection and 45 had a colonic resection. Time to passage of flatus was shorter (18 versus 34 h; P = 0·007), first bowel motion occurred earlier (19 versus 44 h; P = 0·001) and time to feeling hungry was earlier (16 versus 25 h; P = 0·001) in the intervention group. There was no difference in the duration of hospital stay (5 days in the intervention group versus 5·5 days in the control group). Subgroup analyses revealed that the benefits of chewing gum were clearer in patients who had a colonic resection, with a shorter time to first flatus (20 versus 35 h; P = 0·043), first bowel motion (19 versus 53 h; P = 0·014) and feeling hungry (14 versus 40 h; P = 0·001). No adverse events were attributed to chewing gum. Chewing gum is a simple intervention that speeds intestinal transit in patients managed with a recovery programme after laparoscopic colorectal resection. NCT02419586 (https://clinicaltrials.gov/). © 2016 BJS Society Ltd Published by John Wiley & Sons Ltd.

  7. Design, formulation and evaluation of Aloe vera chewing gum.

    Science.gov (United States)

    Aslani, Abolfazl; Ghannadi, Alireza; Raddanipour, Razieh

    2015-01-01

    Aloe vera has antioxidant, antiinflammatory, healing, antiseptic, anticancer and antidiabetic effects. The aim of the present study was to design and evaluate the formulation of Aloe vera chewing gum with an appropriate taste and quality with the indications for healing oral wounds, such as lichen planus, mouth sores caused by cancer chemotherapy and mouth abscesses as well as reducing mouth dryness caused by chemotherapy. In Aloe vera powder, the carbohydrate content was determined according to mannose and phenolic compounds in terms of gallic acid. Aloe vera powder, sugar, liquid glucose, glycerin, sweeteners and different flavors were added to the soft gum bases. In Aloe vera chewing gum formulation, 10% of dried Aloe vera extract entered the gum base. Then the chewing gum was cut into pieces of suitable sizes. Weight uniformity, content uniformity, the organoleptic properties evaluation, releasing the active ingredient in the phosphate buffer (pH, 6.8) and taste evaluation were examined by Latin square method. One gram of Aloe vera powder contained 5.16 ± 0.25 mg/g of phenolic compounds and 104.63 ± 4.72 mg/g of carbohydrates. After making 16 Aloe vera chewing gum formulations, the F16 formulation was selected as the best formulation according to its physicochemical and organoleptic properties. In fact F16 formulation has suitable hardness, lack of adhesion to the tooth and appropriate size and taste; and after 30 min, it released more than 90% of its drug content. After assessments made, the F16 formulation with maltitol, aspartame and sugar sweeteners was selected as the best formulation. Among various flavors used, peppermint flavor which had the most acceptance between consumers was selected.

  8. Locust bean gum: Exploring its potential for biopharmaceutical applications.

    Science.gov (United States)

    Dionísio, Marita; Grenha, Ana

    2012-07-01

    Polysaccharides have been finding, in the last decades, very interesting and useful applications in the biomedical and, specifically, in the biopharmaceutical field. Locust bean gum is a polysaccharide belonging to the group of galactomannans, being extracted from the seeds of the carob tree (Ceratonia siliqua). This polymer displays a number of appealing characteristics for biopharmaceutical applications, among which its high gelling capacity should be highlighted. In this review, we describe critical aspects of locust bean gum, contributing for its role in biopharmaceutical applications. Physicochemical properties, as well as strong and effective synergies with other biomaterials are described. The potential for in vivo biodegradation is explored and the specific biopharmaceutical applications are discussed.

  9. Preparation and characterization of carboxymethyl guar gum nanoparticles.

    Science.gov (United States)

    Gupta, Anek Pal; Verma, Devendra Kumar

    2014-07-01

    Carboxymethyl guar gum nanoparticles (CMGGNPs) were synthesized by nanoprecipitation and sonication method. This method was used for the first time for the synthesis of carboxymethyl guar gum nanoparticles. It was found that the formation of nanoparticles might depend upon the sonication time, solvent, and stirring time. Nanoparticles were characterized by SEM, TEM, XRD and FTIR. The sizes of the particles in suspension have been found in the range 12-30nm. It was concluded that such type of nanoparticles may be used in pharmaceutical and drug delivery.

  10. Rheological property of xanthan gum%黄原胶流变学特性的研究

    Institute of Scientific and Technical Information of China (English)

    刘秀敏; 陈利梅; 李德茂

    2011-01-01

    分别研究了黄原胶浓度、温度、热处理时间、pH值、抗氧化剂VC、氧化剂H2O2、金属离子以及大豆分离蛋白对黄原胶黏度的影响.实验结果表明,随着黄原胶浓度的增大,黏度增大直至基本不变;温度、热处理时间使其黏度稍微有所下降:pH值为6.0时,黏度最大;抗氧化剂VC、氧化剂H2O2使黏度降低;随着金属离子Na+、Fe2+浓度的增大,黄原胶黏度呈下降变化;大豆分离蛋白使黄原胶黏度有所增加.%The effects of xanthan gum concentration, temperature, thermal treatment time, pH, NaOH, NaHCO3, vitamin C, H2O2, metallic ions, and soy protein isolate on the viscosity of xanthan gum were investigated, respectively. The results showed that the viscosity was improved with the increase of xanthan gum until it equaled to a constant. The temperature and treatment time had slightly negative effects on the viscosity. When the pH value was 6.0, the viscosity was highest. The viscosity was decreased with the addition of vitamin C and H2O2. The viscosity decreased undulatedly with the increase of Na+ concentration and Fe2+ concentration. The addition of soy protein isolate increased the viscosity of xanthan gum.

  11. Fluorescence spectral studies of Gum Arabic: Multi-emission of Gum Arabic in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Dhenadhayalan, Namasivayam, E-mail: ndhena@gmail.com [Department of Chemistry, National Taiwan University, Taipei, Taiwan (China); Mythily, Rajan, E-mail: rajanmythily@gmail.com [Department of Chemistry, Dwaraka Doss Goverdhan Doss Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600 106 (India); Kumaran, Rajendran, E-mail: kumaranwau@rediffmail.com [Department of Chemistry, Dwaraka Doss Goverdhan Doss Vaishnav College (Autonomous), 833, Gokul Bagh, E.V.R. Periyar Road, Arumbakkam, Chennai 600 106 (India)

    2014-11-15

    Gum Arabic (GA), a food hydrocolloid is a natural composite obtained from the stems and branches of Acacia Senegal and Acacia Seyal trees. GA structure is made up of highly branched arabinogalactan polysaccharides. Steady-state absorption, fluorescence, and time-resolved fluorescence spectral studies of acid hydrolyzed GA solutions were carried out at various pH conditions. The fluorescence in GA is predominantly attributed to the presence of tyrosine and phenylalanine amino acids. The presence of multi-emissive peaks at different pH condition is attributed to the exposure of the fluorescing amino acids to the aqueous phase, which contains several sugar units, hydrophilic and hydrophobic moieties. Time-resolved fluorescence studies of GA exhibits a multi-exponential decay with different fluorescence lifetime of varying amplitude which confirms that tyrosine is confined to a heterogeneous microenvironment. The existence of multi-emissive peaks with large variation in the fluorescence intensities were established by 3D emission contour spectral studies. The probable location of the fluorophore in a heterogeneous environment was further ascertained by constructing a time-resolved emission spectrum (TRES) and time-resolved area normalized emission spectrum (TRANES) plots. Fluorescence spectral technique is used as an analytical tool in understanding the photophysical properties of a water soluble complex food hydrocolloid containing an intrinsic fluorophore located in a multiple environment is illustrated. - Highlights: • The Manuscript deals with the steady state absorption, emission, fluorescence lifetime and time-resolved emission spectrum studies of Gum Arabic in aqueous medium at various pH conditions. • The fluorescence emanates from the tyrosine amino acid present in GA. • Change in pH results in marked variation in the fluorescence spectral properties of tyrosine. • Fluorescence spectral techniques are employed as a tool in establishing the

  12. Negative differential resistance and effect of defects and deformations in MoS{sub 2} armchair nanoribbon metal-oxide-semiconductor field effect transistor

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Amretashis, E-mail: amretashis@dese.iisc.ernet.in; Mahapatra, Santanu [Nano-Scale Device Research Laboratory, Department of Electronic Systems Engineering, Indian Institute of Science, Bangalore 560 012 (India)

    2013-11-21

    In this work, we present a study on the negative differential resistance (NDR) behavior and the impact of various deformations (like ripple, twist, wrap) and defects like vacancies and edge roughness on the electronic properties of short-channel MoS{sub 2} armchair nanoribbon MOSFETs. The effect of deformation (3°–7° twist or wrap and 0.3–0.7 Å ripple amplitude) and defects on a 10 nm MoS2 ANR FET is evaluated by the density functional tight binding theory and the non-equilibrium Green's function approach. We study the channel density of states, transmission spectra, and the I{sub D}–V{sub D} characteristics of such devices under the varying conditions, with focus on the NDR behavior. Our results show significant change in the NDR peak to valley ratio and the NDR window with such minor intrinsic deformations, especially with the ripple.

  13. Grewia gum as a potential aqueous film coating agent. I: Some physicochemical characteristics of fractions of grewia gum

    Directory of Open Access Journals (Sweden)

    Ikoni J Ogaji

    2013-01-01

    Full Text Available Background: Grewia gum has received attention as a polymeric pharmaceutical excipient in the recent times, being employed as a suspending, film coating, mucoadhesive, and binding agent. The low aqueous solubility, however, has limited its characterization and application. Objective: The purpose of this study was to fractionate and evaluate some physicochemical properties of the gum. Materials and Methods: Aqueous dispersion of the gum was treated at 80΀C for 30 min in the presence of sodium chloride and was subsequently fractionated by successively centrifuging it at 3445 rpm for 30 min. Skeletal density, solubility, particle size, and rheological as well as thermal characteristics of the fractions were evaluated. The 1 H nuclear magnetic resonance (NMR and near infrared (NIR profiles of the fractions were also investigated. The solubility of the gum increased up to fourfold while the viscosity decreased from 244 to as low as70 cP at 40 rpm with some fractions. Results: Grewia gum and the fractions showed good thermal stability exhibiting no thermal events, but charred irreversibly at 297΀C irrespective of the fraction. The molecular weight averages by weight and by number of the fractions were between 233,100 and 235,000. The 1 H nuclear magnetic resonance (NMR spectra showed broad peaks. The NMR and NIR spectra suggested the presence of -OH and -OCH 3 functional groups in this gum. Conclusion: The fractionation improved solubility and facilitated further investigations on its characteristics that may have implication on its processing, application, and optimization as a potential pharmaceutical excipient.

  14. Effects of chewing gum on the stress and work of university students.

    Science.gov (United States)

    Smith, Andrew P; Woods, Martin

    2012-06-01

    Recent research has indicated that chewing gum can relieve perceptions of stress in an occupational sample (Smith, 2009). In the present study, 72 students completed 2 weeks of either chewing gum or refraining from chewing gum. They completed scales measuring perceived stress, anxiety, depression, and single item measures of work levels and tiredness. These were completed both pre- and post-treatment. Perceived stress decreased as a function of the amount of gum chewed. The chewing gum condition was also associated with a decrease in not getting enough academic work done. There were no significant effects of chewing gum on mental health outcomes. These results confirm some of findings from previous studies of chewing gum and stress in other samples.

  15. Effect of enzymatic depolymerization on physicochemical and rheological properties of guar gum.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, B S

    2012-09-01

    Depolymerization of guar gum using enzymatic hydrolysis was performed to obtain depolymerized guar gum having functional application as soluble dietary fiber. Enzymatic hydrolysis of guar gum significantly affected the physicochemical and rheological characteristics of guar gum. The depolymerized guar gum showed a significant increase in crystallinity index from 3.86% to 13.2% and flow behavior index from 0.31 to 1.7 as compared to native guar gum. Remarkable decrease in intrinsic viscosity and consistency index was also observed from 9 to 0.28 and 4.04 to 0.07, respectively. Results revealed that enzymatic hydrolysis of guar gum resulted in a polysaccharide with low degree of polymerization, viscosity and consistency which could make it useful for incorporation in food products as dietary fiber without affecting the rheology, consistency and texture of the products.

  16. Rheological properties and thickening mechanism of aqueous diutan gum solution: Effects of temperature and salts.

    Science.gov (United States)

    Xu, Long; Gong, Houjian; Dong, Mingzhe; Li, Yajun

    2015-11-05

    Rheological properties of a new microbial polysaccharide, diutan gum in aqueous solution have been systematically investigated. It is found that molecular aggregates of diutan gum can be formed at a very low concentration (0.12 g/L), and the mechanism of thickening by diutan gum is proposed. The viscosity retention rate of diutan gum changes little when increasing the temperature from 298 K to 348 K or in a high salinity solution (55.5 g L(-1)). Gel structure can be formed in the diutan gum solution, owing to the finding that the dynamic modulus has an exponential relationship with the concentration. The gel properties of diutan gum are not sensitive to temperature, and are virtually independent of cationic environment (Na(+) and Ca(2+)). The temperature/salt tolerance of the diutan gum solution is mainly attributed to its perfect double helix molecular conformation, the location of the side chains of its molecules, and its water retention capacity.

  17. Grewia Gum 1: Some Mechanical and Swelling Properties of ...

    African Journals Online (AJOL)

    Erah

    Technology, University of Jos, Nigeria, 3Pharmacy, School of Applied ... effect of temperature on the water uptake of the compacts was studied and the ... than those of pullulan and guar gum with elastic moduli of 3.33±0.00 and ... cause significant changes in the properties of ... middle belt region of the country where the.

  18. Investigation of Transport Properties of a New Biomaterials - GUM Mangosteen

    Science.gov (United States)

    Pradhan, Sourav S.; Sarkar, A.

    2006-06-01

    Biomaterial has occupied leading position in material science for various scientific and technological applications. This present work is carried out over a natural gum extracted from raw fruit of Mangosteen, an east Indian tree (Gercinia Mangostana) following extraction and purification process. Solid specimen of the said gum is developed following sol-gel like process. AC and DC electrical analysis on the dried solid specimen of the gum were carried out and showed high electrical conduction with σ ~ 1 E-03 S/cm, of which ionic and electronic contributions are 70% and 30% respectively. Analysis shows that origin of high electrical conductivity is due to presence of substantial amount of organic acid unit in its polysaccharide background. In fact the observed σ is about 1000 times of that observed in gum Arabica. Optical absorption of this new bio- materials are also studied using UV-VIS analysis. The results show its high absorption co-efficient in UV and blue part of analysed range. A complete electrical characterization of the material have been made. It has also been observed that the electronic conduction can be enhanced to 70% of the total electrical conductivity by forming complex with Iodine and organic (Citric) acid from Lemon fruit. This high potential material is being studied for development of electronic device application.

  19. Cetirizine release from cyclodextrin formulated compressed chewing gum

    DEFF Research Database (Denmark)

    Stojanov, Mladen; Larsen, Kim Lambertsen

    2012-01-01

    Beside the efficient effect on masking cetirizine bitter taste, the cyclodextrins (CDs) as well could have influence on the release from the formulation. In vitro release profiles of cetirizine from compressed chewing gums containing α-, β- and γ-CD were investigated using a three cell chewing...

  20. Economics of the gum arabic value chain in Senegal

    NARCIS (Netherlands)

    Mujawamariya, G.

    2012-01-01

     A Gum arabic has an important international market due to its use in various industries. Senegal is a small producing country whose exports are low probably due to problems of developing internal markets resulting from the lack of price incentives. The study’s main aim is to link the mar

  1. Gellan gum fluid gels for topical administration of diclofenac.

    Science.gov (United States)

    Mahdi, Mohammed H; Conway, Barbara R; Mills, Thomas; Smith, Alan M

    2016-12-30

    Diclofenac topical formulations are often preferred for drug administration to patients who experience serious GIT problems. Absorption of the drug through the skin, however, can be challenging due to the natural protective feature of the stratum corneum (SC). In this article, fluid gels prepared from gellan gum were explored as a topical drug delivery vehicle. Rheological analysis of the formulations showed that it was possible to produce a topical gel with a viscosity and the mechanical strength similar to that of the commercially available Voltaren(®) gel using 1% w/w of a 50:50 low acyl/high acyl (LA/HA) gellan blend. Soft-tribology was used to assess the lubrication properties of gellan fluid gels. The lubrication of the gellan gum fluid gel formulations at high rubbing speeds was similar to the lubrication of the Voltaren(®) gel. The use of gellan gum dramatically increased skin permeation of diclofenac when compared with the commercially available formulation and could be controlled by changing the gellan gum concentration and/or sodium ion concentration in the formulation. This study highlights the potential use of fluid gels that can be easily tuned to have physical properties suitable for topical formulations with the added advantage of increasing drug permeation.

  2. 75 FR 44251 - Wood Oils and Gums, and Streptomyces

    Science.gov (United States)

    2010-07-28

    ... AGENCY EPA-HQ-OPP-2010-0441; FRL-8829-8 Wood Oils and Gums, and Streptomyces Strain K61; Registration...). Streptomyces Strain K61 is a naturally occurring soil bacterium and is classified as a microbial pesticide. It...-mail Address Streptomyces Strain K61 (6066) EPA-HQ-OPP-2009-05 Anna Gross, (703) 09 305-5614,...

  3. Ceramic to metal seal

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Gary S. (Albuquerque, NM); Wilcox, Paul D. (Albuquerque, NM)

    1976-01-01

    Providing a high strength, hermetic ceramic to metal seal by essentially heating a wire-like metal gasket and a ceramic member, which have been chemically cleaned, while simultaneously deforming from about 50 to 95 percent the metal gasket against the ceramic member at a temperature of about 30 to 75 percent of the melting temperature of the metal gasket.

  4. Investigation of Mechanical Properties and Plastic Deformation Behavior of (Ti45Cu40Zr10Ni5100−xAlx Metallic Glasses by Nanoindentation

    Directory of Open Access Journals (Sweden)

    Lanping Huang

    2014-01-01

    Full Text Available The effect of Al addition on mechanical properties and plastic deformation behavior of (Ti45Cu40Zr10Ni5100−xAlx (x = 0, 2, 4, 6 and 8 amorphous alloy ribbons have been investigated by nanoindentation. The hardness and elastic modulus do not simply increase with the increase of Al content. The alloy with 8 at.% Al exhibits the highest hardness and elastic modulus. The serrations or pop-in events are strongly dependent on the loading rate and alloy composition.

  5. Relationships Between Gum Chewing and Stroop Test: A Pilot Study.

    Science.gov (United States)

    Kawakami, Y; Takeda, T; Konno, M; Suzuki, Y; Kawano, Y; Ozawa, T; Kondo, Y; Sakatani, K

    2017-01-01

    Cognitive function tends to decrease with aging, therefore maintenance of this function in an aging society is an important issue. The role of chewing in nutrition is important. Although several studies indicate that gum chewing is thought to improve cognitive function, it remains debatable whether gum-chewing does in fact improve cognitive function. The Stroop test is a psychological tool used to measure cognition. A shorter reaction time indicates a mean higher behavioral performance and higher levels of oxy-Hb concentration. fNIRS is a powerful, non-invasive imaging technique offering many advantages, including compact size, no need for specially equipped facilities, and the potential for real-time measurement. The left dorsolateral prefrontal cortex (DLPFC) seems to be mainly involved in the Stroop task.The aim of the present study was to investigate the hypothesis that gum-chewing changes cerebral blood flow in the left DLPFC during the Stroop test, and also changes the reaction time. Fourteen healthy volunteers (mean age 26.9 years) participated in this study after providing written informed consent. A piece of tasteless gum weighing 1.0 g was used. Each session was designed in a block manner, i.e. 4 rests (30 s) and 3 blocks of task (30 s). A computerized Stroop test was used (including both congruent and incongruent Stroop tasks) which calculates a response time automatically. The Binominal test was used for comparisons (p gum chewing significantly increases responses/oxy-Hb concentration and significantly shortens the reaction time.

  6. Gellan gum: a new biomaterial for cartilage tissue engineering applications.

    Science.gov (United States)

    Oliveira, J T; Martins, L; Picciochi, R; Malafaya, P B; Sousa, R A; Neves, N M; Mano, J F; Reis, R L

    2010-06-01

    Gellan gum is a polysaccharide manufactured by microbial fermentation of the Sphingomonas paucimobilis microorganism, being commonly used in the food and pharmaceutical industry. It can be dissolved in water, and when heated and mixed with mono or divalent cations, forms a gel upon lowering the temperature under mild conditions. In this work, gellan gum hydrogels were analyzed as cells supports in the context of cartilage regeneration. Gellan gum hydrogel discs were characterized in terms of mechanical and structural properties. Transmissionelectron microscopy revealed a quite homogeneous chain arrangement within the hydrogels matrix, and dynamic mechanical analysis allowed to characterize the hydrogels discs viscoelastic properties upon compression solicitation, being the compressive storage and loss modulus of approximately 40 kPa and 3 kPa, respectively, at a frequency of 1 Hz. Rheological measurements determined the sol-gel transition started to occur at approximately 36 degrees C, exhibiting a gelation time of approximately 11 s. Evaluation of the gellan gum hydrogels biological performance was performed using a standard MTS cytotoxicity test, which showed that the leachables released are not deleterious to the cells and hence were noncytotoxic. Gellan gum hydrogels were afterwards used to encapsulate human nasal chondrocytes (1 x 10(6) cells/mL) and culture them for total periods of 2 weeks. Cells viability was confirmed using confocal calcein AM staining. Histological observations revealed normal chondrocytes morphology and the obtained data supports the claim that this new biomaterial has the potential to serve as a cell support in the field of cartilage regeneration.

  7. Chewing gum increases energy expenditure before and after controlled breakfasts.

    Science.gov (United States)

    Kresge, Daniel L; Melanson, Kathleen

    2015-04-01

    Chewing has been associated with improved satiation and satiety, but little is known about the metabolic impact of gum chewing. We tested the hypothesis that gum chewing would increase energy expenditure (EE) and reduce respiratory exchange ratio (RER) before and after a controlled test meal. Seventeen males and 13 females (age 21.5 ± 6.6 years, body mass index 23.9 ± 2.8 kg/m(2)) participated in a randomized crossover study in which subjects chewed sugar-free gum for a total of 1 h (3 sessions of 20 min) on the test day (GC) and did not chew gum on a control day (NG). EE and RER were measured by indirect calorimetry after an overnight fast. Subjects consumed a breakfast shake containing 30% of their measured energy needs, and then postprandial EE and RER were measured for 3 h. Blood glucose (GLC) was measured in the fasting and postprandial states at regular intervals. Fasting EE was higher during GC (1.23 ± 0.04 kcal/min; 1 kcal = 4.2 kJ) than during NG (1.17 ± 0.04 kcal/min; p = 0.016). Postprandial EE was also higher during GC (1.46 ± 0.05 kcal/min) than during NG (1.42 ± 0.05 kcal/min; p = 0.037). Fasting and postprandial RER and GLC did not differ between GC and NG. The findings demonstrate that GC is associated with higher fasting and postprandial EE without altering blood glucose or substrate oxidation as measured by RER. These data suggest that gum chewing potentially could influence short-term energy balance in this population; however, longer-term research is needed.

  8. Naturalistic assessment of demand for cigarettes, snus, and nicotine gum.

    Science.gov (United States)

    Stein, Jeffrey S; Wilson, A George; Koffarnus, Mikhail N; Judd, Michael C; Bickel, Warren K

    2017-01-01

    Behavioral economic measures of demand provide estimates of tobacco product abuse liability and may predict effects of policy-related price regulation on consumption of existing and emerging tobacco products. In the present study, we examined demand for snus, a smokeless tobacco product, in comparison to both cigarettes and medicinal nicotine. We used both a naturalistic method in which participants purchased these products for use outside the laboratory, as well as laboratory-based self-administration procedures. Cigarette smokers (N = 42) used an experimental income to purchase their usual brand of cigarettes and either snus or gum (only one product available per session) across a range of prices, while receiving all products they purchased from one randomly selected price. In a separate portion of the study, participants self-administered these products during laboratory-based, progressive ratio sessions. Demand elasticity (sensitivity of purchasing to price) was significantly greater for snus than cigarettes. Elasticity for gum was intermediate between snus and cigarettes but was not significantly different than either. Demand intensity (purchasing unconstrained by price) was significantly lower for gum compared to cigarettes, with no significant difference observed between snus and cigarettes. Results of the laboratory-based, progressive ratio sessions were generally discordant with measures of demand elasticity, with significantly higher "breakpoints" for cigarettes compared to gum and no significant differences between other study products. Moreover, breakpoints and product purchasing were generally uncorrelated across tasks. Under naturalistic conditions, snus appears more sensitive to price manipulation than either cigarettes or nicotine gum in existing smokers.

  9. The analysis method of deformation for laser cutting sheet metal part%激光切割钣金件时的工件变形分析方法

    Institute of Scientific and Technical Information of China (English)

    郭建; 兰天亮; 陈康

    2011-01-01

    利用ANSYS有限元分析软件建立了适合激光切割钣金件的三维实体模型,介绍了钣金件在自身重力和激光切割热源共同作用下,进行切割时工件变形大小的计算方法.将激光切剖热源简化为高斯热源,运用APDL语言分析计算了激光切剖时实际工件的变形大小.%ANSYS, finite element analysis software is used to establish a 3d entity model suited to the analysis of laser cutting sheet metal part.This paper introduces a method to detemine the size of workpiece deformation when it is cutted by laser under its own gravity and the action of the laser cutting heat source,and then simplifies the laser cutting heat source as the gauss heat source,analyzes and calculates the size of workpiece deformation when it is cutting by laser by writing APDL program

  10. Saffron and beetroot extracts encapsulated in maltodextrin, gum Arabic, modified starch and chitosan: Incorporation in a chewing gum system.

    Science.gov (United States)

    Chranioti, Charikleia; Nikoloudaki, Aspasia; Tzia, Constantina

    2015-08-20

    Maltodextrin (MD-21DE), gum Arabic (GA), gum Arabic-modified starch (GA-MS), modified starch-chitosan (MS-CH) and modified starch-maltodextrin-chitosan (MS-MD-CH) were used as agents for beetroot and saffron coloring-extracts microencapsulation by freeze drying. The produced powders were evaluated in terms of coloring strength (E) during storage at 40°C for 10 weeks and a first-order kinetic was applied. Color parameters (L(*), a(*), b(*), C(*) and ΔE(*)) and water sorption behavior was also studied. Moreover, incorporation of the powders in a chewing gum model system was conducted. The type of encapsulating agent significantly (PGA>GA-MS>MS-CH>MS-MD-CH. The water sorption study revealed that MD and GA kept their structural integrity up to water activities of 0.66 and 0.82, respectively. The chewing gum samples produced with coloring extracts encapsulated in GA-MS showed the greatest a(*)(for beetroot) and b(*) (for saffron) values indicating a better protection.

  11. Comparative Analysis of Properties and Microstructure of the Plastically Deformed Alloy Inconel®718, Manufactured by Plastic Working and Direct Metal Laser Sintering

    Directory of Open Access Journals (Sweden)

    Żaba K.

    2016-03-01

    Full Text Available Nickel superalloys as Inconel® are materials widely used in the aerospace industry among others for diffusers, combustion chamber, shells of gas generators and other. In most cases, manufacturing process of those parts are used metal strips, produced by conventional plastic processing techniques, and thus by hot or cold rolling. An alternative technology allowing for manufacturing components for jet engines is the technique of 3D printing (additive manufacturing, and most of all Direct Metal Laser Sintering, which is one of the latest achievement in field of additive technologies.

  12. First-principles study of band-gap change in deformed nanotubes

    Science.gov (United States)

    Shan, Bin; Lakatos, Gregory W.; Peng, Shu; Cho, Kyeongjae

    2005-10-01

    The effects of cross-sectional deformation and bending on the electronic structures of single-wall carbon nanotubes (SWNTs) are examined. Upon increasing the deformation, semiconducting SWNTs undergo semiconductor-metal transition, and the conduction band and valence band show asymmetric response to the deformation. The metallic tubes' electronic structures are relatively insensitive to similar mechanical deformation. Using the properties of deformed nanotubes, we propose a conceptual design of SWNT-based single-electron quantum-well devices.

  13. Mechanical Deformation of Ship Stern-Shaft Mechanical Face Seals

    Institute of Scientific and Technical Information of China (English)

    朱汉华; 刘正林; 温诗铸; 严新平

    2004-01-01

    In ship propeller shaft systems, the shaft seal is a mechanical face seal, which includes a stationary metal seal ring and a rotating ring.The seal faces are deformed with different loads.The deformation of the seal faces affects the performance of mechanical face seals, which leads to water leakage, so the seal face deformation must be analyzed.A mechanics model with deformation equations was developed to describe ship stern-shaft seals.An example was given to verify the deformation equations.The solution of the deformation equations gives a theoretical basis for the analysis of seal leakage and improvements of seal structures.

  14. The effect of used deformation, metal sheath and heat treatment on the I-V curve of ex situ MgB 2 composite

    Science.gov (United States)

    Kováč, P.; Hušek, I.; Melišek, T.

    2004-01-01

    Current-voltage characteristics of MgB 2 composite wires made of ex situ process using Cu, Fe and stainless steel (SS) sheaths have been measured at 4.2 K in the self-field and external magnetic field between 2 and 4 T. It was found that the used mode of deformation (drawing, rotary swaging and two-axial rolling) influences the slope of I-V curve due to affected grain connectivity. Final heat treatment at 950 °C/0.5 h improves grain connectivity apparently, which results in I-V characteristic with very high n-exponents. The n-exponents of multi-core wires measured in external field are apparently lower due to a current sharing among the non-uniform filaments surrounded by high resistance matrix.

  15. In search for incentives to gum arabic collection and marketing in Senegal: Interlocking gum trade with pre-finances from traders

    NARCIS (Netherlands)

    Mujawamariya, G.; Haese, D' M.F.C.

    2012-01-01

    In interlocked contractual relationships traders' supplies of inputs and cash to producers during the growing season is reimbursed with harvests. This study analyses interlocking contracts in gum arabic production in Senegal. Gum arabic is a natural exudation of Acacia senegal trees that grow in the

  16. 苦苈胶压裂液研究:冻胶性质%Gel Properties of Kuli Gum Fracturing Fluid

    Institute of Scientific and Technical Information of China (English)

    张栌丹; 潘竟军; 徐冬梅; 韩晓强; 陈国锦

    2011-01-01

    Crosslinldng properties and viscoelastic of kuli ( vegetable-gum) and guar gum fracturing fluid were studied. Kuli gum could be used as a thickener in water-base-fracture fluid. The viscosity of kuli gel and guar gel increased with increasing concentration of powder when it reacted with crosslinkers. The viscosity of kuli gel was little higher than that of guar gel after 30 minutes sheering at the same concentration. The results showed that the kuli gum had a better anti-sheered property. At the gum crosslinldng pH value, the viscosity of kuli gel and guar gel increased with increasing pH value. When the pH value increased from 8.78 to 10.24, the viscosity of kuli gel increased from 85.46 mPa-s to 167.25 mPa-s. The influence of metallic ion to the gel viscosity was marked with valence state. The viscosity of kuli gel and guar gel decreased with increasing concentration of metal cation. The viscosity of kuli gel was better than that of guar gel at the same metallic ion concentration. The viscosity of kuli gel decreased from 400 mPa-s to 250 mPa-s, and that of the extra grade guar gum gel and second grade guar gum gel decreased by 45.8% and 63.9% respectively with Ca * concentration of 0-4 g/L. The gum could not crosslink when Fe3 * was added. The results of viscosity test showed that C and C of kuli gel were higher than that of guar gel. The viscolastic property of kuli gum was better.%比较了苦苈胶、瓜尔胶压裂液的交联特性和黏弹性.苦苈胶可以作为油田水基压裂液的增稠剂,与硼砂和有机硼交联时,冻胶黏度随胶粉浓度的增加而增加;相同浓度下剪切30min,苦苈胶冻胶黏度略高于瓜尔胶冻胶,耐剪切性较好.在能形成冻胶的pH值范围内,冻胶黏度随pH值的增加而增加;当pH值从8.78增至10.24时,苦苈胶冻胶黏度由85.46mPa·s增至167.25mPa·s.金属离子价态越高,对冻胶黏度的影响越大;金属离子浓度越高,冻胶黏度越小.离子浓度相同时,苦苈胶冻

  17. Use of Cassia javahikai seed gum and gum-g-polyacrylamide as coagulant aid for the decolorization of textile dye solutions.

    Science.gov (United States)

    Sanghi, Rashmi; Bhattacharya, Bani; Singh, Vandana

    2006-07-01

    Investigations were carried out for possible exploitation of Cassia javahikai seeds as potential source of commercial gum for the textile wastewater treatment. Graft copolymerization with acrylamide was done to modify the seed gum for the favorable properties. C. javahikai seed gum, and its copolymer grafted with acrylamide were synthesized in the presence of oxygen using potassium persulphate/ascorbic acid redox system. Both C. javahikai seed gum (CJ) and its grafted-polyacrylamide (CJG), were found to be good working substitutes as coagulant aids in conjunction with PAC, for the decolorization of all the dyes in varying ratios. CJ and CJG alone could effectively decolorize direct dyes (DBR and DO) and in conjunction with a very low dose of PAC could decolorize all the dyes (DBR, DO, ASR, and PBB) to more than 70%. Grafting also increased the decolorizing ability of CJ gum.

  18. PENGGUNAN GUM XANTHAN PADA SUBSTITUSI PARSIAL TERIGU DENGAN TEPUNG JAGUNG DALAM PEMBUATAN ROTI [Use of Xanthan Gum in Partial Substitusion of Corn Flour for Wheat Flour in Breadmaking

    Directory of Open Access Journals (Sweden)

    Posman Sibuea

    2001-08-01

    Full Text Available The objective of the experiment was to examine the capabilities of composite flour (i.e. corn flour and wheat flour and xanthan gum in breadmaking. Breads were produced using mixture of wheat and corn flour at varios ratio with addition of xanthan gum at different level (0.0% to 0.75%. The result showed that the composite flour had significant effect on all measured parameters. As the wheat flour descreaseed down to 65% the dought length, texture, reducing sugar content increased, but the sensory values descresed, xanthan gum had significant effect on the texture, reducing sugar content, the sensory values and the dough length. As the xanthan gum increased, the dough length, the reducing sugar content increased, whereas the texture increased at 0.50% the descreased at 0.75%. the bread of good acceptability was produced from the floaur mixture of wheat flour (70% and corn flour (30% using 0.75% of xanthan gum.

  19. Bioinspired synthesis of morphologically controlled SrCO{sub 3} superstructures by natural gum acacia

    Energy Technology Data Exchange (ETDEWEB)

    Sreedhar, B.; Keerthi Devi, D. [Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology Council of Scientific and Industrial Research, Hyderabad 500607 Andhra Pradesh (India); Satyavani, C. [Dept. of Chemistry, Acharya Nagarjuna University P. G. Centre, Nuzividu-521201, Andhra Pradesh (India); Dept. of Chemistry, GITAM University, Visakhapatnam-530045, Andhra Pradesh (India); Rambabu, C. [Dept. of Chemistry, Acharya Nagarjuna University P. G. Centre, Nuzividu-521201, Andhra Pradesh (India); Basaveswara Rao, M.V. [Dept. of Chemistry, Krishna University, Machilipatnam-521001, Andhra Pradesh (India); Saratchandra Babu, M. [Dept. of Chemistry, GITAM University, Visakhapatnam-530045, Andhra Pradesh (India)

    2011-05-15

    Crystallization of strontium carbonate is performed in aqueous solution using Gum Acacia (GA) as crystal growth modifier. A novel study of hierarchical assembly, specifically interacting inorganic and natural component without introduction of other additives was studied. SrCO{sub 3}structures exhibiting the morphologies of well defined nanocrystallites in the form of clusters of hexagonal rods, flower shaped, cross like, doughnut shaped and rice grain shaped are identified by optimizing the conditions and concentration of GA. In continuation, morphology was also examined for mixed metal carbonates (Sr-LaCO{sub 3}, Sr-TbCO{sub 3}). The results indicate that -OH, -COOH and -NH{sub 2} functional group moieties of GA play a remarkable role in inhibiting growth morphology of metal carbonates and mixed metal carbonates. Structural characterization of the synthesized materials was investigated by Powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive analysis (EDAX), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) coupled Mass (MS) and Fourier transform infrared spectroscopy (FT-IR). This synthesis method can be easily extended to a variety of inorganic nanoparticles, thereby enabling exact control over material properties. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Sulfomethylated graft copolymers of xanthan gum and polyacrylamide

    Energy Technology Data Exchange (ETDEWEB)

    Cottrell, I.W.; Empey, R.A.; Racciato, J.S.

    1978-08-08

    A water-soluble anionic graft copolymer of xanthan gum and polyacrylamide is described in which at least part of the amide function of the acrylamide portion of the copolymer is sulfomethylated and the xanthan gum portion of the copolymer is unreacted with formaldehyde. The copolymer is sulfomethylated by reaction with formaldehyde and sodium metabisulfite. The formaldehyde does not cause any appreciable cross-linking between hydroxyl groups of the xanthan moieties. The sulfomethylation of the acrylamido group takes place at temperatures from 35 to 70 C. The pH is 10 or higher, typically from 12 to 13. The degree of anionic character may be varied by adjusting the molar ratio of formaldehyde and sodium metabisulfite with respect to the copolymer. 10 claims.

  1. Locust bean gum: Exploring its potential for biopharmaceutical applications

    Directory of Open Access Journals (Sweden)

    Marita Dionísio

    2012-01-01

    Full Text Available Polysaccharides have been finding, in the last decades, very interesting and useful applications in the biomedical and, specifically, in the biopharmaceutical field. Locust bean gum is a polysaccharide belonging to the group of galactomannans, being extracted from the seeds of the carob tree (Ceratonia siliqua. This polymer displays a number of appealing characteristics for biopharmaceutical applications, among which its high gelling capacity should be highlighted. In this review, we describe critical aspects of locust bean gum, contributing for its role in biopharmaceutical applications. Physicochemical properties, as well as strong and effective synergies with other biomaterials are described. The potential for in vivo biodegradation is explored and the specific biopharmaceutical applications are discussed.

  2. Synthesis of Hydroxypropyl Guar Gum by Phase Transfer Catalysis

    Institute of Scientific and Technical Information of China (English)

    Rong Chun XIONG; Ming Zhu CHANG; Jian Ming CHEN; Nan ZHOU; Gang WEI

    2005-01-01

    HGG (Hydroxypropyl guar gum) was synthesized by phase transfer catalysis for the first time. The effects of alkalinity, phase transfer catalyst, etherification, pH value, temperature,reaction time and stirring speed were investigated. An optimal synthetic reaction technology was established, namely, dose of guar gum is 100 g, propylene oxide 40-50 g, HTAC (hexadecyl trimethyl ammonium chloride ) 1.3-1.7 g, pH value 10-10.5, temperature 45-50℃, and reaction time 3-4 hours. The result shows that the improved HGG has high viscosity. Its dissolution speed, content of insoluble residue, colloid light transparency and stability are apparently superior to guar flour.

  3. Synthesis and Aqueous Solution Viscosity of Hydrophobically Modified Xanthan Gum

    Institute of Scientific and Technical Information of China (English)

    QIAN Xiao-lin; WU Wen-hui; YU Pei-zhi; WANG Jian-quan

    2007-01-01

    Two xanthan gum derivatives hydrophobically modified by 4 or 8 tetradecyl chains per 100 xanthan gum structure units were synthesized. The derivatives were studied by scanning electron microscope and pyrene fluorescence spectrometry. And the aqueous solution apparent viscosity of the derivatives was investigated. The results indicate that the network of the derivatives with more hydrophobic groups is closer and tighter. With increasing of alkyl chain substitution degree, the hydrophobically associating interactions enhance in aqueous solution. Aqueous solution apparent viscosity of the derivatives increases with increasing of polymer concentration and alkyl substitution degree, and decreases with the increase of temperature. In the brine solution, the strong viscosity enhancement phenomenon appears. The interaction between the derivatives and surfactant sodium dodecylbenzene sulfonate is strong.

  4. Chewing gum and lozenges as delivery systems for noscapine

    DEFF Research Database (Denmark)

    Norgaard Jensen, L.; Christrup, Lona Louring; Menger, N.

    1991-01-01

    Chewing gum and lozenges were evaluated as delivery systems for noscapine with the aim of developing improved antitussive preparations. The formulations studied were prepared with both the water-soluble hydrochloride salt of noscapine and with the poorly soluble embonate salt and noscapine free...... base. The release characteristics of the preparations were evaluated both in vitro and in vivo, and their taste properties examined. Only the formulations containing noscapine base were without any appreciable taste. Chewing gum containing this compound showed, however, a low level of drug release both...... in vitro and in vivo and is therefore not a suitable dosage form. Only a lozenge formulation containing noscapine base fulfilled the requirements of taste acceptability and adequate release properties....

  5. Chemical and Functional Properties of Chia Seed (Salvia hispanica L.) Gum.

    Science.gov (United States)

    Segura-Campos, Maira Rubi; Ciau-Solís, Norma; Rosado-Rubio, Gabriel; Chel-Guerrero, Luis; Betancur-Ancona, David

    2014-01-01

    Chia (Salvia hispanica L.) constitutes a potential alternative raw material and ingredient in food industry applications due to its dietary fiber content. Gum can be extracted from its dietary fiber fractions for use as an additive to control viscosity, stability, texture, and consistency in food systems. The gum extracted from chia seeds was characterized to determine their quality and potential as functional food additives. The extracted chia gum contained 26.2% fat and a portion was submitted to fat extraction, producing two fractions: gum with fat (FCG) and gum partly defatted (PDCG). Proximal composition and physicochemical characterization showed these fractions to be different (P seed is an excellent natural source of gum with good physicochemical and functional qualities, and is very promising for use in food industry.

  6. Protein-free cress seed (Lepidium sativum) gum: Physicochemical characterization and rheological properties

    DEFF Research Database (Denmark)

    Razmkhah, Somayeh; Razavi, Seyed Mohammad Ali; Mohammadifar, Mohammad Amin

    2016-01-01

    proper-ties and thermal stability of cress seed gum. Mechanical spectra of the CSG and PFCSG were classified asweak gels and PFCSG showed stronger and more elastic network structure. The gum dispersions exhib-ited strong shear-thinning behavior which was described satisfactory by the Herschel......Protein-free cress seed gum (PFCSG) was obtained by precipitation of crude cress seed gum (CSG) withethanol followed by treatment with protease. Molecular weight, moisture, ash and uronic acids contentdecreased after elimination of protein. Elimination of protein improved significantly rheological......-Bulkley and Mooremodels. Protein-free cress seed gum had higher apparent and intrinsic viscosities than the crude gum.CSG indicated lower hysteresis loop area, but degree of structural recovery of the samples showed no sig-nificant difference. The main decomposition of PFCSG started above 213◦C with two peaks (at 261...

  7. X-ray diffraction, IR spectroscopy and thermal characterization of partially hydrolyzed guar gum.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, B S

    2012-05-01

    Guar gum was hydrolyzed using cellulase from Aspergillus niger at 5.6 pH and 50°C temperature. Hydrolyzed guar gum sample was characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, dilute solution viscometry and rotational viscometry. Viscometry analysis of native guar gum showed a molecular weight of 889742.06, whereas, after enzymatic hydrolysis, the resultant product had a molecular weight of 7936.5. IR spectral analysis suggests that after enzymatic hydrolysis of guar gum there was no major transformation of functional group. Thermal analysis revealed no major change in thermal behavior of hydrolyzed guar gum. It was shown that partial hydrolysis of guar gum could be achieved by inexpensive and food grade cellulase (Aspergillus niger) having commercial importance and utilization as a functional soluble dietary fiber for food industry.

  8. Influence of tragacanth gum in egg white based bioplastics: Thermomechanical and water uptake properties.

    Science.gov (United States)

    López-Castejón, María Luisa; Bengoechea, Carlos; García-Morales, Moisés; Martínez, Inmaculada

    2016-11-05

    This study aims to extend the range of applications of tragacanth gum by studying its incorporation into bioplastics formulation, exploring the influence that different gum contents (0-20wt.%) exert over the thermomechanical and water uptake properties of bioplastics based on egg white albumen protein (EW). The effect of plasticizer nature was also evaluated through the modification of the water/glycerol ratio within the plasticizer fraction (fixed at 40wt.%). The addition of tragacanth gum generally yielded an enhancement of the water uptake capacity, being doubled at the highest content. Conversely, presence of tragacanth gum resulted in a considerable decrease in the bioplastic mechanical properties: both tensile strength and maximum elongation were reduced up to 75% approximately when compared to the gum-free system. Ageing of selected samples was also studied, revealing an important effect of storage time when tragacanth gum is present, possibly due to its hydrophilic character.

  9. Management of blue gum eucalyptus in California requires region-specific consideration

    Directory of Open Access Journals (Sweden)

    Kristina M. Wolf

    2016-01-01

    Full Text Available Blue gum eucalyptus (Eucalyptus globulus is a large tree native to Australia that was widely planted throughout California for reforestation, building and timber, but in some areas has spread beyond its planted borders and substantially altered wildlands. Due to its fast growth, large size and reproductive potential, blue gum's impacts on native vegetation, wildlife and ecosystem processes are of concern, particularly in areas with reliable year-round rainfall or fog, where it is most likely to spread. Depending on levels of invasion and rate of spread, blue gum may have negative, positive or neutral impacts on fire regimes, water and nutrient availability, understory vegetation and higher trophic levels. Additional research on the abiotic and biotic impacts of blue gum, quantitative estimates of area covered by blue gum, and weed risk assessments that allow for region-specific climatic information and management goals to be incorporated are needed to guide management of blue gum populations.

  10. Characterization of gum ghatti (Anogeissus latifolia): a structural and rheological approach.

    Science.gov (United States)

    Kaur, Lovedeep; Singh, Jaspreet; Singh, Harjinder

    2009-08-01

    Gatifolia, a commercial gum ghatti (Anogeissus latifolia) product was studied for its structural, thermal, and rheological characteristics. This study may prove helpful for the use of gum ghatti in a diverse range of food applications. The molecular weight (M(W)) and R(g) (radius of gyration) for gum ghatti were calculated to be approximately 8.94 x 10(7) g/mol and 140 nm, respectively, using high-performance size exclusion chromatography (HPSEC) system combined with multi-angle laser light scattering (MALLS). Gum ghatti solutions exhibited pseudoplastic behavior (as determined by flow experiments), which became more prevalent with increasing concentrations. Gum ghatti also displayed time-dependent shear-thickening behavior and showed negative hysteresis during up-down flow measurements. Under the measurement conditions at the range of frequencies and temperatures studied, the gum did not behave as a typical viscoelastic gel.

  11. Adult sudden death caused by aspiration of chewing gum.

    Science.gov (United States)

    Njau, S N

    2004-01-28

    A case of a fatal foreign material aspiration is presented in the following text. A 24-year-old white male died suddenly. A piece of chewing gum lodged in a pool of frothy fluid was revealed at autopsy. Microscopic examinations revealed atelectasia emphysema, eosinophilic exudate and empty spaces. Blood and urine samples were analyzed, for alcohol and drug use by fluorescence polarization immunoassay (FPIA) on an Abbott AXSYM system. No alcohol or other drugs were detected in blood or urine.

  12. Radiation induced degradation of xanthan gum in the solid state

    Science.gov (United States)

    Şen, Murat; Hayrabolulu, Hande; Taşkın, Pınar; Torun, Murat; Demeter, Maria; Cutrubinis, Mihalis; Güven, Olgun

    2016-07-01

    In this study, the effect of ionizing radiation on xanthan gum was investigated. Xanthan samples were irradiated with gamma rays in air at ambient temperature in the solid state at different dose rates and doses. Change in their molecular weights was followed by size exclusion chromatography (SEC). Chain scission yield (G(S)), and degradation rate constants (k) were calculated. The calculated G(S) values are 0.0151±0.0015, 0.0144±0.0020, 0.0098±0.0010 μmol/J and k values are 1.4×10-8±1.4×10-9, 1.3×10-8±2.0×10-9, 8.7×10-9±1.0×10-9 Gy-1 for 0.1, 3.3 and 7.0 kGy/h dose rates, respectively. It was observed that the dose rate was an important factor controlling the G(S) and degradation rate of xanthan gum. Considering its use in food industry, the effect of irradiation on rheological properties of xanthan gum solutions was also investigated and flow model parameters were determined for all dose rates and doses. Rheological analysis showed that xanthan solution showed non-Newtonian shear thinning behaviour and ionizing radiation does not change the non-Newtonian and shear thinning flow behaviour of xanthan gum solutions in concentration ranges of this work. It was determined that, Power Law model well described the flow behaviour of unirradiated and irradiated xanthan solutions.

  13. Gellan gum microgel-reinforced cell-laden gelatin hydrogels

    OpenAIRE

    Shin, Hyeongho; Olsen, Bradley D.; Khademhosseini, Ali

    2013-01-01

    The relatively weak mechanical properties of hydrogels remain a major drawback for their application as load-bearing tissue scaffolds. Previously, we developed cell-laden double-network (DN) hydrogels that were composed of photocrosslinkable gellan gum (GG) and gelatin. Further research into the materials as tissue scaffolds determined that the strength of the DN hydrogels decreased when they were prepared at cell-compatible conditions, and the encapsulated cells in the DN hydrogels did not f...

  14. In vivo mucoadhesive strength appraisal of gum Manilkara zapota

    OpenAIRE

    Singh Sudarshan; Bothara Sunil B

    2015-01-01

    The mucilage (MMZ) extracted from the seeds of Manilkara zapota(Linn.) P. Royen syn. using maceration techniques was evaluated for mucoadhesive strength by various in vitro and in vivo methods. The result showed that mucoadhesive strength of seeds mucilage have comparable property toward natural and synthetic polymers such as Guar Gum and hydroxyl propyl methyl cellulose (HPMC E5LV) under the experimental conditions used in this study. Briefly, it could be concluded that the seed mucilage of ...

  15. Hepatoprotective triterpenes from the gum resin of Boswellia carterii.

    Science.gov (United States)

    Wang, Yan-Gai; Ma, Qin-Ge; Tian, Jin; Ren, Jin; Wang, Ai-Guo; Ji, Teng-Fei; Yang, Jian-Bo; Su, Ya-Lun

    2016-03-01

    Ten tirucallane-type triterpenes named boscartene A-J and a nor-tetracyclic triterpene boscartene K, together with ten known compounds were isolated from the gum resin of Boswellia carterii Birdw. Their structures and absolute configurations were elucidated by extensive spectroscopic analysis. In vitro assay, some of these compounds (10 μM) showed moderate hepatoprotective activities against d-galactosamine-induced HL-7702 cell damage.

  16. Physical Properties of Gum Karaya-Starch-Essential Oil Patches

    OpenAIRE

    2010-01-01

    Essential oils are used in foods, cosmetics, and pharmaceuticals. Despite the recent marketing of novel essential-oil-containing patches, there is no information on their production, constituents, or physical properties. The objectives of this study were to produce essential-oil patches and characterize their physical properties. The essential oil of Lavandula angustifolia (lavender) was included at concentrations of 2.5% to 10% in patches manufactured from the exudate gum karaya, propylene g...

  17. Synergistic gelation of xanthan gum with locust bean gum: a rheological investigation.

    Science.gov (United States)

    Copetti, G; Grassi, M; Lapasin, R; Pricl, S

    1997-12-01

    Many industrial products often include in their formulation more than one polysaccharide to achieve the desired properties during and after processing. Many such mixed systems behave as would be expected from the known properties of the individual polymers. In others, however, their properties are superior to those of either component alone, or may be qualitatively different. In many polysaccharide systems, the combination of a gelling polymer with a nongelling one gives rise to strong synergistic effects, as a consequence of interaction among different chain polymers and formation of mixed junction zones. Probably, the most exploited mixed gels, especially by the food industry, are those involving the microbial polysaccharide xanthan gum (XG) and the plant galactomannans, like locust bean gum (LBG). Concentrated aqueous systems of LBG and XG display quite different rheological properties: the former show the behaviour typical of hyperentangled macromolecular solutions, whereas the flow and viscoelastic properties of XG systems correspond to those of tenuous, weak-gel networks. Interestingly, when mixed together these macromolecules interact to form a firm, thermoreversible gel with synergistic effects. In the present paper we report the results of a thorough investigation of both polymer concentration and temperature effects on the rheological properties of mixed LBG-XG systems in 20 mM KCl under continuous and oscillatory flow conditions. Under continuous shear at 25 degrees C, pure LBG shows the flow properties of a macromolecular solution, with a shear-thinning behaviour and a Newtonian region at low shear rates, whereas the rheological behaviour of XG and all LX mixed systems is that typical of weak-gels. Furthermore, in the mixed systems the viscosity values do not increase monotonically with increasing xanthan concentration, but the synergistic effect has a maximum in accordance with the XG:LBG ratio 1:1. As the temperature is increased from 25 degrees C to

  18. Elastic Properties in Tension and Shear of High Strength Nonferrous Metals and Stainless Steel - Effect of Previous Deformation and Heat Treatment

    Science.gov (United States)

    1947-03-01

    and 18:8 Cr-Ni steel crystals, however, are probably similar to that for gold (fig. 31). The diagram for a body-centered cubic metal, alpha iron , is...32). The directional variation of the shearing modulus (G-), as illus- trated by the diagram for alpha iron in figure 3*1-, is opposite to that of...of aluminum. ^ m OJ > O > tea o o o Figure 33.- Directional variation of the tensile modulus of elastioity of a crystal of alpha iron . Figure

  19. Effect of chewing gum on the bowel motility after cholecystectomy

    Directory of Open Access Journals (Sweden)

    Khadije Yazdi

    2011-07-01

    Full Text Available Background: Postoperative ileus is common after cholecystectomy, causes gas retension, distention, nausea, vomiting, and even pain. Chewing gum is a type of sham feeding that may reduce the duration of postoperative ileus. This study determines the effect of chewing gum in the immediate postoperative period to facilitate ileus recovery following cholecystectomy. Material & Methods: This is a randomized controlled trial in 2009. Twenty-four patients undergoing cholecystectomy and they divided in to two equal groups (n=12. Patients in group A chewed sugarless gum there time after surgery, each time 20 miniutes in 4, 10 and 18 hours after finishing sugery. Demographics, intraoperative, and postoperative care data did not reveal any significant difference between two groups. The data resending the first passage of flatus, defecation and bowel sound in every 2 hours for each patient completed in questioning. Data were analyzed using SPSS software version-13.5 and student t-test. Results: The first bowel sound heard 3 ±1.3 and 2.8 ±1.3 hours post-operatively in cases and controls, respectively. The above findings were not significant between two groups. Furthermore gas passing reported at 18.3±10.5 and 36.28±12.6 hours post-operation in case and control groups respectively. The first defecation was occured at 36.8 ±21.7 and 69.5 ±19.2 hours after operation in case and control groups, respectively

  20. Low viscosity hydrogel of guar gum: preparation and physicochemical characterization.

    Science.gov (United States)

    Cunha, Pablyana L R; Castro, Rondinelle R; Rocha, Francisco A C; de Paula, Regina C M; Feitosa, Judith P A

    2005-10-30

    Guar gum was cross-linked with glutaraldehyde and characterized by GPC, rheology, WADX, SEM and TGA. This guar gum is a galactomannan polysaccharide, that contains small amount of arabinose, glucose and uronic acid, besides galactose and mannose. The polymer has high molar mass, with Mw, Mn and Mv values of 2.0x10(6), 1.2x10(6) and 1.9x10(6)g/mol, respectively. The reticulation follows a slow process and lead to a viscosity increase of 40 times compared with the original gum solution. The final viscosity was similar to that of Hylan G-F 20, a hyaluronate derivative, commercially used in viscosupplementation treatment. The gel contains 95.6% of water and the amount of residual glutaraldehyde is much lower than the LD-50. Porous structure was detected by SEM and thermal stability was improved by the cross-linking. The low viscosity, the small amount of remained glutaraldehyde, and the thermal stability indicates that the guar hydrogel has potential to be applied as biomaterial with specific rheological requirements.

  1. Xanthan gum stabilized gold nanoparticles: characterization, biocompatibility, stability and cytotoxicity.

    Science.gov (United States)

    Pooja, Deep; Panyaram, Sravani; Kulhari, Hitesh; Rachamalla, Shyam S; Sistla, Ramakrishna

    2014-09-22

    Xanthan gum (XG) has been widely used in food, pharmaceutical and cosmetic industries. In the present study, we explored the potential of XG in the synthesis of gold nanoparticle. XG was used as both reducing and stabilizing agent. The effect of various formulation and process variables such as temperature, reaction time, gum concentration, gum volume and gold concentration, in GNP preparation was determined. The XG stabilized, rubey-red XGNP were obtained with 5 ml of XG aqueous solution (1.5 mg/ml). The optimum temperature was 80°C whereas the reaction time was 3 h. The optimized nanoparticles were also investigated as drug delivery carrier for doxorubicin hydrochloride. DOX loaded gold nanoparticles (DXGP) were characterized by dynamic light scattering, TEM, FTIR, and DSC analysis. The synthesized nanoparticle showed mean particle size of 15-20 nm and zeta potential -29.1 mV. The colloidal stability of DXGP was studied under different conditions of pH, electrolytes and serum. Nanoparticles were found to be stable at pH range between pH 5-9 and NaCl concentration up to 0.5 M. In serum, nanoparticles showed significant stability up to 24h. During toxicity studies, nanoparticles were found biocompatible and non-toxic. Compared with free DOX, DXGP displayed 3 times more cytotoxicity in A549 cells. In conclusion, this study provided an insight to synthesize GNP without using harsh chemicals.

  2. The Digestion of Guar Gum by Individual Strains of Colonic Bacteria

    OpenAIRE

    Tomlin, J.; Read, N W; Edwards, C. A.; Duerden, B. I.

    2011-01-01

    Experiments were carried out to determine the range of human colonic bacteria that could ferment the viscous polysaccharide, guar gum, and to seek evidence for collaboration between different strains of colonic bacteria. Single strains of a variety of species of bacteria isolated from human faeces were incubated with guar gum. Only seven ofthe 57 different strains of bacteria tested could alter the viscosity and pH of guar gum. These seven strains were all of the fragilis group of the genus B...

  3. Dodecenylsuccinic Anhydride Derivatives of Gum Karaya (Sterculia urens): Preparation, Characterization, and Their Antibacterial Properties

    OpenAIRE

    Padil, V.V.T.; Senan, Chandra; Cernik, M

    2015-01-01

    Esterifications of the tree-based gum, gum karaya (GK), using dodecenylsuccinic anhydride (DDSA) were carried out in aqueous solutions. GK was deacetylated using alkali treatment to obtain deacetylated gum karaya (DGK). The DGK and its DDSA derivative were characterized using gel permeation chromatography/multiangle laser light scattering (GPC/MALLS), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), proton nuclear magnetic re...

  4. Chemical and Functional Properties of Chia Seed (Salvia hispanica L.) Gum

    OpenAIRE

    Maira Rubi Segura-Campos; Norma Ciau-Solís; Gabriel Rosado-Rubio; Luis Chel-Guerrero; David Betancur-Ancona

    2014-01-01

    Chia (Salvia hispanica L.) constitutes a potential alternative raw material and ingredient in food industry applications due to its dietary fiber content. Gum can be extracted from its dietary fiber fractions for use as an additive to control viscosity, stability, texture, and consistency in food systems. The gum extracted from chia seeds was characterized to determine their quality and potential as functional food additives. The extracted chia gum contained 26.2% fat and a portion was submit...

  5. Effects of Chewing Different Flavored Gums on Salivary Flow Rate and pH

    Directory of Open Access Journals (Sweden)

    Maryam Karami Nogourani

    2012-01-01

    Full Text Available Chewing gum increases salivary flow rate (SFR and pH, but differences in preferences of gum flavor may influence SFR and pH. The aim of this paper was to assess the effect of five different flavors of sucrose-free chewing gum on the salivary flow rate and pH in healthy dental students in Isfahan, Iran. Fifteen (7 men and 8 women healthy dental student volunteers collected unstimulated saliva and then chewed one of five flavored gums for 6 min. The whole saliva was collected and assessed for 6 consecutive days. After unstimulated saliva was collected, stimulated saliva was collected at interval of 0-1, 1–3, and 3–6 minutes after the start of different flavored chewing gums. The SFR and salivary pH were measured. The SFR increased in all five flavored gums at 1, 3, and 6 minutes after start of chewing gums (<0.001. The flow rate of all products reached peak in the 1st minute of stimulation, except spearmint-flavored gums which reached peak in the 6th minute. In the 1st minute, the strawberry-flavored gums showed the highest SFR. During 1–3 minutes, strawberry- and apple-flavored gums showed higher SFR, respectively. Only the spearmint- and cinnamon-flavored gum significantly increased salivary pH. Gum flavored can affect the SFR and pH and special flavors can be advised for different individuals according to their oral conditions.

  6. EVALUATION OF MORINGA OLEIFERA GUM AS A BINDER IN TABLET FORMULATION

    OpenAIRE

    Patil Basawaraj S; Soodam Srinivas R.; Kulkarni Upendra; Korwar Prakassh G.

    2010-01-01

    Various plant gums have been used as binders in tablet formulations. But still finding novel binder for the manufacture of tablets, in pharmaceutical industry. The Moringa oleifera gum was found its binding property. In the present study Moringa oleifera gum was employed as a binding agent in Chloroquine phosphate tablets at concentrations of 4.0, 6.0 and 8.0 % w/w, in comparison with potato starch. The properties of Moringa oleifera gum were evaluated for angle of repose, bulk density, tappe...

  7. Locust bean gum: processing, properties and food applications--a review.

    Science.gov (United States)

    Barak, Sheweta; Mudgil, Deepak

    2014-05-01

    Locust bean gum or carob gum is a galactomannan obtained from seed endosperm of carob tree i.e. Ceratonia siliqua. It is widely utilized as an additive in various industries such as food, pharmaceuticals, paper, textile, oil well drilling and cosmetics. Industrial applications of locust bean gum are due to its ability to form hydrogen bonding with water molecule. It is also beneficial in the control of many health problems like diabetes, bowel movements, heart disease and colon cancer due to its dietary fiber action. This article focuses on production, processing, composition, properties, food applications and health benefits of locust bean gum.

  8. Chemical and Physical Properties, Safety and Application of Partially Hydrolized Guar Gum as Dietary Fiber

    OpenAIRE

    2007-01-01

    The ideal water-soluble dietary fiber for the fiber-enrichment of foods must be very low in viscosity, tasteless, odorless, and should produce clear solutions in beverages. Partially hydrolyzed guar gum (PHGG) produced from guar gum by enzymatic process has the same chemical structure with intact guar gum but less than one-tenth the original molecular length of guar gum, which make available to be used as film former, foam stabilizer and swelling agent. The viscosity of PHGG is about 10 mPa·s...

  9. Dietary guar gum reduces lymph flow and diminishes lipid transport in thoracic duct-cannulated rats.

    Science.gov (United States)

    Shirouchi, Bungo; Kawamura, Sayaka; Matsuoka, Ryosuke; Baba, Sanae; Nagata, Kazuko; Shiratake, Sawako; Tomoyori, Hiroko; Imaizumi, Katsumi; Sato, Masao

    2011-08-01

    Guar gum has a well-recognized hypolipidemic effect. This effect is thought to be due to the physicochemical properties of guar gum, which may cause changes in adsorption of lipids or the viscosity of the intestinal contents. Guar gum is a non-specific absorption inhibitor of any type of lipid-soluble compound. Permanent lymph duct cannulation was performed on rats to investigate the effects of dietary guar gum on lymph flow and lipid transport. Rats fed a 5% guar gum diet were compared with those fed a 5% cellulose diet, and lymph was collected after feeding. The water-holding capacity (WHC), settling volume in water (SV), and viscosity of guar gum were compared with those of cellulose. Rats fed with the guar gum diet had significantly lower lymph flow and lymphatic lipid transport than did rats fed with the cellulose diet. The WHC, SV, and viscosity of guar gum were significantly higher than those of cellulose. We propose that dietary guar gum reduces lymph flow and thereby diminishes lipid transport by means of its physicochemical properties related to water behavior in the intestine.

  10. Rapid screening of guar gum using portable Raman spectral identification methods.

    Science.gov (United States)

    Srivastava, Hirsch K; Wolfgang, Steven; Rodriguez, Jason D

    2016-01-25

    Guar gum is a well-known inactive ingredient (excipient) used in a variety of oral pharmaceutical dosage forms as a thickener and stabilizer of suspensions and as a binder of powders. It is also widely used as a food ingredient in which case alternatives with similar properties, including chemically similar gums, are readily available. Recent supply shortages and price fluctuations have caused guar gum to come under increasing scrutiny for possible adulteration by substitution of cheaper alternatives. One way that the U.S. FDA is attempting to screen pharmaceutical ingredients at risk for adulteration or substitution is through field-deployable spectroscopic screening. Here we report a comprehensive approach to evaluate two field-deployable Raman methods--spectral correlation and principal component analysis--to differentiate guar gum from other gums. We report a comparison of the sensitivity of the spectroscopic screening methods with current compendial identification tests. The ability of the spectroscopic methods to perform unambiguous identification of guar gum compared to other gums makes them an enhanced surveillance alternative to the current compendial identification tests, which are largely subjective in nature. Our findings indicate that Raman spectral identification methods perform better than compendial identification methods and are able to distinguish guar gum from other gums with 100% accuracy for samples tested by spectral correlation and principal component analysis.

  11. Formulation of Eco-friendly Medicated Chewing Gum to Prevent Motion Sickness.

    Science.gov (United States)

    Shete, Rahul B; Muniswamy, Vimalkumar J; Pandit, Ashlesha P; Khandelwal, Kishanchandra R

    2015-10-01

    An attempt was made to formulate medicated chewing gum to prevent motion sickness using natural gum base for faster onset of action and easy administration, anywhere and anytime, without access to water. To avoid the discard issue of gum cud, natural gum base of Triticum aestivum (wheat grain) was explored because of its biodegradable and biocompatible nature and easy availability. Prolamin, extracted from wheat, showed good chewing capacity, elasticity, high water retention capacity, antifungal activity, and compatibility with the drug. Formulations were prepared based on a two-factor and three-level factorial design. Amount of calcium carbonate (texturizer) and gum base were selected as independent variables. Elasticity and drug release were considered as the dependent variables. All batches were evaluated for the content uniformity, elasticity study, texture study, in vitro drug release study, and chewiness study. Results revealed that medicated chewing gum containing 80 mg of calcium carbonate and 500 mg of gum base showed good elasticity and more than 90% drug release within 16 min. Thus, this study suggested that both good elasticity and chew ability and abundant availability of wheat grain can act as a potential gum base for medicated chewing gum.

  12. Pharmacognostic studies of gums collected from aprocot trees growing in Armenia and perspectives of their use.

    Science.gov (United States)

    Chichoyan, N

    2009-11-01

    Plant polysaccharides are widely used in the food and confectionary industries, as an emulsifier, flavour encapsulator, and thickening agent. The apricot tree has a gum that oozes out in the spring and it seems to be a lot like gum Arabic. Gums collected from apricot trees growing in Armenia (RA) are considered as exudates of ecological significance. Besides, in food industry it can entirely replace the more expensive gum Arabic as well as its synthetic derivatives. Periodically organized resource potential studies in the regions of RA gives the opportunity to have an exact notion of biological and utilized resources of gums as a natural exudates of cultivated apricot trees of the country. The study was conducted on gums collected from the apricot trees of Armavir region (Armavir, Edjmiatsin, Baghramyan) that were purified by general physical methods without any chemical or enzymatic influence. According to obtained results--from one apricot tree was collected 54.15+/- 4.41 g/m(2), the biological resource of apricot gum was 45 ton. We also determined the quantities of Mg, K and Ca in apricot gum by atomic--absorptive method (Mg - 18 mg/kg; Ca - 5.8 mg/kg; K - 15.7 mg/kg). The study results also revealed that addition of gummi armeniaca increases the yeast biomass up to 55%. According to above mentioned and the great resources of raw material of apricot tree gum it can be approved its usage in the food industry in Armenia.

  13. Whole and crushed nutlets of chia (Salvia hispanica from Mexico as a source of functional gums

    Directory of Open Access Journals (Sweden)

    Maira Segura-Campos

    2014-12-01

    Full Text Available The objective of this study was to characterize the chemical and functional properties of Mexican chia (Salvia hispanica gums extracted from defatted whole and crushed nutlets using the Soxhlet and SFE-CO2 methods. Chia gums have interesting chemical and functional properties for the food industry. The oil and gum yields were in the range of 1.98-16.42% and 5.81-12.60%, respectively. The defatting procedure did not affect significantly the oil and gum extraction; the nutlet type (whole or crushed was the only parameter influencing the yield. The proximate composition and the protein and fiber contents of chia gum were evaluated. Low contents of protein and fiber and high NFE levels were found in whole nutlet gums. The functional properties of chia gum extracted from whole and crushed nutlets with the Soxhlet and SFE-COs methods showed the following ranges of water absorption capacity of 62.64 to 143.66 g/g, water adsorption capacity of 0.69 to 1.35 g/g, and water and oil holding capacity of 100 to 149.28 g/g and19.5 to 40.4 g/g, respectively. The rheological behavior exhibited by the gums was pseudoplastic or shear thinning. From a functional perspective, chia gum is an important food component due its emulsifier and stabilizer potentials.

  14. Fabrication of electrospun almond gum/PVA nanofibers as a thermostable delivery system for vanillin.

    Science.gov (United States)

    Rezaei, Atefe; Tavanai, Hossein; Nasirpour, Ali

    2016-10-01

    In this study, the fabrication of vanillin incorporated almond gum/polyvinyl alcohol (PVA) nanofibers through electrospinning has been investigated. Electrospinning of only almond gum was proved impossible. It was found that the aqueous solution of almond gum/PVA (80:20, concentration=7% (w/w)) containing 3% (w/w) vanillin could have successfully electrospun to uniform nanofibers with diameters as low as 77nm. According to the thermal analysis, incorporated vanillin in almond gum/PVA nanofibers showed higher thermal stability than free vanillin, making this composite especially suitable for high temperature applications. XRD and FTIR analyses proved the presence of vanillin in the almond gum/PVA nanofibers. It was also found that vanillin was dispersed as big crystallites in the matrix of almond gum/PVA nanofibers. FTIR analysis showed almond gum and PVA had chemical cross-linking by etheric bonds between COH groups of almond gum and OH groups of PVA. Also, in the nanofibers, there were no major interaction between vanillin and either almond gum or PVA.

  15. Glycinin-gum arabic complex formation: Turbidity measurement and charge neutralization analysis.

    Science.gov (United States)

    Dong, Die; Hua, Yufei

    2016-11-01

    The interaction between glycinin and anionic polysaccharides has gained considerable attention recently because of its scientific impact on the stability of acid soymilk systems. In this study, the formation of glycinin/gum arabic complexes driven by electrostatic interactions was investigated. Turbidity titrations at different glycinin/gum arabic ratios were conducted and critical pH values (pHφ1) where insoluble complexes began forming were determined firstly. The corresponding pHφ1 values at glycinin/gum arabic ratios of 1:4, 1:2, 1:1, 2:1, 4:1 and 8:1 were 2.85, 3.25, 3.70, 4.40, 4.85 and 5.35, respectively. Afterwards, electromobilities for glycinin and gum arabic at the pH values between 4.1 and 2.6 were measured, and charge densities (ZN) for glycinin and gum arabic were calculated based on the soft particle analysis theory. Further analysis indicated that the product of glycinin/gum arabic ratio (ρ) and ZN ratio of glycinin/gum arabic was approximate 1 at any pHφ1 values. It was revealed that charge neutralization was achieved when glycinin/gum arabic insoluble complexes began forming. NaCl displayed multiple effects on glycinin/gum arabic complex formation according to turbidity and compositional analysis. The present study could provide basic guidance in acid soymilk designing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Self-healing guar gum and guar gum-multiwalled carbon nanotubes nanocomposite gels prepared in an ionic liquid.

    Science.gov (United States)

    Sharma, Mukesh; Mondal, Dibyendu; Mukesh, Chandrakant; Prasad, Kamalesh

    2013-10-15

    Guar gum is a galactomannan extracted from the seed of the leguminous shrub Cyamopsis tetragonoloba. It was found to form a soft viscoelastic gel in 1-butyl-3-methylimidazolium chloride, an ionic liquid at an optimized concentration of 10%w/v. A nanocomposite gel of the gum with enhanced strength could be prepared with 0.2%w/v of multiwalled carbon nanotubes (MWCNTs) in the ionic liquid. When the gels thus prepared were subjected to surface fractures or bisected completely, they found to self-heal at room temperature without any external interventions. The self-healing process could be repeated several times. These viscoelastic gel systems showed thixotropic nature and recovery of the storage modulus with time for several cycles was observed upon rheological investigations. The interaction took place between ionic liquid, guar gum and MWCNT was studied by SEM, TEM, FT-IR, powder XRD and rheometry. The results suggested that, upon standing at room temperature development of electrostatic interactions and the van der Waals interactions among the ionic liquid molecules facilitated the formation of reversible noncovalent bonds and eventually activated the self-healing in the gel systems through appropriate chain entanglements.

  17. (120) and (122-bar) monazite deformation twins

    Energy Technology Data Exchange (ETDEWEB)

    Hay, R.S

    2003-10-20

    Unusual features of (120) and (122-bar) deformation twins in monazite (monoclinic LaPO{sub 4}) are described and analyzed. These features are kinks and other irregularities in (120) twins, and V-shaped indentations on (120) and (122-bar) twin planes. Twinning shear analysis suggests that the kinks are a type II deformation twin mode with shear direction ({eta}{sub 1}) of [21-bar0]. This complements previous analysis based on atom shuffling considerations. Shear strain compatibility requires extensive plastic deformation in the kink. The V-shaped indentations may be analogous to similar structures in b.c.c metal deformation twins. Deformation mechanisms that may be associated with these structures are discussed.

  18. Milk protein-gum tragacanth mixed gels: effect of heat-treatment sequence.

    Science.gov (United States)

    Hatami, Masoud; Nejatian, Mohammad; Mohammadifar, Mohammad Amin; Pourmand, Hanieh

    2014-01-30

    The aim of this study was to investigate the role of the heat-treatment sequence of biopolymer mixtures as a formulation parameter on the acid-induced gelation of tri-polymeric systems composed of sodium caseinate (Na-caseinate), whey protein concentrate (WPC), and gum tragacanth (GT). This was studied by applying four sequences of heat treatment: (A) co-heating all three biopolymers; (B) heating the milk-protein dispersion and the GT dispersion separately; (C) heating the dispersion containing Na-caseinate and GT together and heating whey protein alone; and (D) co-heating whey protein with GT and heating Na-caseinate alone. According to small-deformation rheological measurements, the strength of the mixed-gel network decreased in the order: C>B>D>A samples. SEM micrographs show that the network of sample C is much more homogenous, coarse and dense than sample A, while the networks of samples B and D are of intermediate density. The heat-treatment sequence of the biopolymer mixtures as a formulation parameter thus offers an opportunity to control the microstructure and rheological properties of mixed gels.

  19. Microstructural evolution of viscoelastic emulsions stabilised by sodium caseinate and xanthan gum.

    Science.gov (United States)

    Moschakis, Thomas; Murray, Brent S; Dickinson, Eric

    2005-04-15

    The time-dependent evolution of the phase-separated microstructure of a caseinate-stabilised emulsion containing xanthan gum added before emulsification has been investigated by confocal laser scanning microscopy, image analysis and rheology. Moderately low levels of xanthan addition lead to depletion flocculation and gravity-induced phase separation. Increasing the polysaccharide concentration causes immobilisation of the microstructure due to an increase in the local viscoelasticity: that is, the emulsion structure cannot easily rearrange to expel xanthan-enriched aqueous serum phase because a weak gel-like network is generated. The effect of xanthan on the evolving microstructure of phase-separated regions, which reflects indirectly the local emulsion micro-rheology, has been estimated from image analysis of time sequences of confocal micrographs. A comparison has been made between object shape analysis using four different shape descriptors. The roundness parameter has been found to be a convenient descriptor for reliably quantifying the structural change in terms of the relaxation rate of xanthan-rich aqueous drops. The Taylor parameter has been used to link the kinetics of drop relaxation to the time-dependent small-deformation rheological behaviour. The analysis of the combined experimental data reveals the difficulty of relating the evolving microstructure to bulk rheological measurements.

  20. Mechanical properties of a Gum-type Ti-Nb-Zr-Fe-O alloy

    Science.gov (United States)

    Nocivin, Anna; Cinca, Ion; Raducanu, Doina; Cojocaru, Vasile Danut; Popovici, Ion Alexandru

    2017-08-01

    A new Gum-type alloy (Ti-Nb-Zr-Fe-O) in which Fe is used instead of Ta was subjected to a particular thermomechanical processing scheme to assess whether its mechanical characteristics (fine β-grains with high strength and low modulus) render it suitable as a biomedical implant material. After a homogenization treatment followed by cold-rolling with 50% reduction, the specimens were subjected to one of three different recrystallization treatments at 1073, 1173, and 1273 K. The structural and mechanical properties of all of the treated specimens were analyzed. The mechanical characterization included tensile tests, microhardness determinations, and fractography by scanning electron microscopy. The possible deformation mechanisms were discussed using the \\overline {Bo} - \\overline {Md} diagram. By correlating all of the experimental results, we concluded that the most promising processing variant corresponds to recrystallization at 1073 K, which can provide suitable mechanical characteristics for this type of alloys: high yield and ultimate tensile strengths (1038 and 1083 MPa, respectively), a low modulus of elasticity (62 GPa), and fine crystalline grain size (approximately 50 μm).

  1. In-situ studies of bulk deformation structures: Static properties under load and dynamics during deformation

    DEFF Research Database (Denmark)

    Jakobsen, Bo

    2006-01-01

    The main goal of the study presented in this thesis was to perform in-situ investigations on deformation structures in plastically deformed polycrystalline copper at low degrees of tensile deformation (metals. Anovel synchrotron...... grains in polycrystalline samples during tensile deformation. We have shown that the resulting 3D reciprocal space maps from tensile deformed copper comprise a pronounced structure, consisting of bright sharp peaks superimposed on a cloud of enhanced intensity. Based on the integrated intensity......, the width of the peaks, and spatial scanning experiments it is concluded that the individual peaks arise from individual dislocation-free regions (the subgrains) in the dislocation structure. The cloud is attributed to the dislocation rich walls. Samples deformed to 2% tensile strain were investigated under...

  2. Cubic wavefunction deformation of compressed atoms

    CERN Document Server

    Portela, Pedro Calvo

    2015-01-01

    We hypothesize that in a non-metallic crystalline structure under extreme pressures, atomic wavefunctions deform to adopt a reduced rotational symmetry consistent with minimizing interstitial space in the crystal. We exemplify with a simple numeric variational calculation that yields the energy cost of this deformation for Helium to 25%. Balancing this with the free energy gained by tighter packing we obtain the pressures required to effect such deformation. The consequent modification of the structure suggests a decrease in the resistance to tangential stress, and an associated decrease of the crystal's shear modulus. The atomic form factor is also modified. We also compare with neutron matter in the interior of compact stars.

  3. Deformation of vanadium and niobium during hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Geld, P.V.; Kats, M.IA.; Spivak, L.V.

    1986-01-01

    The deformation behavior of polycrystalline vanadium and niobium during hydrogenation is investigated experimentally using a torsional pendulum to load 0.5-mm-diameter, 80-mm-long wire specimens. It is found that under conditions of isothermal hydrogenation, the macrodeformation of the V and Nb specimens is determined by the contributions of the following two components: deformation due to changes in the shear modulus of the system metal-hydrogen and deformation due to the oriented growth of the hydride phase in an applied stress field. 9 references.

  4. Caracterização reológica da goma xantana: influência de íons metálicos univalente e trivalente e temperatura em experimentos dinâmicos Rheological characterization of xanthan gum: influence from univalent and trivalent metallic ions and from the temperature in dynamic experiments

    Directory of Open Access Journals (Sweden)

    Samuel Luporini

    2011-01-01

    Full Text Available As propriedades dinâmicas das soluções aquosas de goma xantana com e sem adição de NaCl ou Al2(SO43.18H2O foram medidas em um reômetro de deformação controlada aplicando ciclos de aquecimento e resfriamento. O tempo de relaxação decresceu com o aumento da temperatura; no entanto, este tempo aumentou com a adição de sal nas soluções de 0,5% em peso de goma xantana, mas diminuiu com a adição de 1%. Durante o aquecimento das soluções de goma xantana pura ocorreu uma mudança de conformação a 51 °C, e durante o resfriamento foi observada a formação de duas estruturas: entre 86 e 47 °C e abaixo de 47 °C. Com a adição de sal não houve mudança conformacional durante o aquecimento, enquanto no resfriamento duas estruturas foram novamente observadas, mas para faixas de temperatura diferentes.The dynamic rheological properties of water xanthan gum solutions with and without the addition of NaCl or Al2(SO43.18H2O were measured in a strain controlled rheometer applying heating and cooling cycles. The terminal relaxation time decreased with increasing temperature. This time increased with the addition of 0.5 wt. (% of salt, but decreased when 1 wt. (% was added. During heating a conformational change occurred at 51 °C and upon cooling two structures were observed between 86 and 47 °C and below 47 °C. When salt was added there was no conformational change during heating, but the two structures again appeared during cooling, though at different temperature ranges.

  5. Enhancement of welan gum production in Sphingomonas sp. HT-1 via heterologous expression of Vitreoscilla hemoglobin gene.

    Science.gov (United States)

    Liu, Xiaoliu; Zhu, Ping; Jiang, Ruifan; Wu, Lingtian; Feng, Xiaohai; Li, Sha; Xu, Hong

    2017-01-20

    Welan gum is a microbial polysaccharide produced by Sphingomonas sp. Its production is limited by the dissolved oxygen levels in the highly viscous fermentation. A strategy of heterologous expression of the Vitreoscilla hemoglobin gene in Sphingomonas sp. HT-1 was investigated to alleviate oxygen limitation and improve the yield of welan gum. Ultimately, the welan gum production increased from 25.3g/L to 34.6g/L, whereas the rheological behavior of welan gum solutions remained virtually unchanged. The transcriptional levels of the key genes in the electron transfer chain, TCA cycle and welan gum synthesis pathway, as well as ATP level revealed that the VHb expression in Sphingomonas sp. HT-1 enhanced welan gum biosynthesis by improving respiration and ATP supply. This study would pave the genetic manipulation way for enhancing welan gum yield, and it's also of great importance for the industrial applications of welan gum under harsh conditions.

  6. Evaluation of microscopic deformation behaviors of metal matrix composite by means of SFC test and acoustic emission (Part I :Effect of heat treatment on IFSS)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun; Kang, Moon Phil [Pusan National University, Pusan (Korea, Republic of)

    1998-11-15

    Metal matrix composites(MMCs) are rapidly becoming one of the strongest candidates for structural materials for high temperature application. It is well recognized that MMCs always experience at least one large cool-down from processing temperature before any significant applied service loading. Due to the large difference in thermal expansion coefficient between the fiber and matrix, large thermal residual stresses generally develop in composites. It was reported from many previous studies that the effects of thermal residual stress on mechanical properties and fracture behavior were much more complex and dramatic than conventional engineering materials. Therefore it is crucial to evaluate the effect of heat treatment which changes the characteristic of distribution of thermal residual stress in MMCs. Single fiber composite(SFC) test based on the balance in a micromechanical model is a quite convenient method to evaluate interfacial shear strength(IFSS) and the failure mode of composite. In this study the effect of heat treatment on IFSS and the microscopic failure mechanism of MMC is investigated by combining acoustic emission(AE) technique with fragmentation test. The characteristic of AE signal, IFSS and microscopic failure mechanism due to heat treatment condition is discussed.

  7. Evaluation of Microscopic Deformation Behaviors of Metal Matrix Composite due to Heat Treatment by means of SFC Test and Acoustic Emission

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Moon Phil; Lee, Joon Hyun [Pusan National University, Busan (Korea, Republic of)

    2000-10-15

    Metal matrix composite(MMCs) have been rapidly becoming one of the strongest candidates for structural materials for high temperature application. It is well recognized that MMCs always experience at least one large cool-down from processing temperature before my significant applied service loading. Due to the large difference in thermal expansion coefficient between the fiber and matrix, large thermal residual stresses generally develop in composites. It was reported from many previous studies that the effects of thermal residual stress on mechanical properties and fracture behavior were much more complex and dramatic than conventional engineering materials. Therefore it is crucial to evaluate the effect of heat treatment which changes the characteristic of distribution of thermal residual stress in MMCs. Single fiber composite(SFC) test based on the balance in a micromechanical model is a quite convenient method to evaluate interfacial shear strength(IFSS) and the failure mode of composite. In this study the effect of heat treatment on IFSS and the microscopic failure mechanism of MMC is investigated by combining acoustic emission(AE) technique with SFC test. The characteristic of AE signal, IFSS and microscopic failure mechanism due to heat treatment condition is discussed

  8. In vitro evaluation of Moringa oleifera gum for colon-specific drug delivery.

    Science.gov (United States)

    Singhal, Anil Kumar; Jarald, Edwin E; Showkat, Ahmad; Daud, Anwar

    2012-01-01

    Moringa gum obtained from stem of the plant Moringa oleifera Lam. belonging to family Moringaceae. Number of naturally occurring polysaccharides obtained from plant (guar gum, inulin), animal (chitosan, chondrotin sulphate), algal (alginates) or microbial (dextran) origin. The present study was evaluated Moringa oleifera gum as a carrier for colon specific drug delivery using in vitro drug release studies. Six formulations of curcumin were prepared using varying concentration of Moringa oleifera gum containing 50 mg curcumin by wet granulation method. Tablets were subjected for evaluation by studying the parameter like hardness, friability, drug content uniformity and in vitro drug release study. Hardness was found to be in the range of 5.5 to 7.3 kg/cm(2), the percentage friability was in the range of 0.60 to 0.89%, and tablet showed 98.99% to 99.89% of the labeled amount of curcumin indicating uniformity in drug content. In vitro drug release study was performed using simulated stomach, intestinal and colonic fluid. The susceptibility of Moringa gum to colonic bacteria was also assessed using drug release study with rat caecal contents. 30% Moringa gum containing formulation (F-3) was shown better drug released that is 90.46%, at the end of 24 h of dissolution study in the presence of rat caecal contents in comparison to 40% Moringa gum containing formulation (F-4) that was 78.03%. The results illustrate the usefulness of Moringa olefera gum as a potential carrier for colon-specific drug delivery.

  9. Compositional analysis and rheological characterization of gum tragacanth exudates from six species of Iranian Astragalus

    DEFF Research Database (Denmark)

    Balaghi, Sima; Mohammadifar, Mohammad Amin; Zargaraan, Azizollaah

    2011-01-01

    The sugar composition and viscoelastic behaviour of Iranian gum tragacanth exuded by six species of Astragalus was investigated at a concentration of 1.3% and varying ionic strength using a controlled shear-rate rheometer. Compositional analysis of the six species of gum tragacanth by high...

  10. Characterisation and molecular association of Nigerian and Sudanese Acacia gum exudates

    Science.gov (United States)

    The chemical and physicochemical characteristics of gum exudate samples harvested from mature trees of Acacia senegal at two specific locations in Nigeria have been investigated together with gum samples harvested from Acacia senegal and Acacia seyal originating from Sudan. The monosaccharide sugar ...

  11. Ethanol-resistant ethylcellulose/guar gum coatings--importance of formulation parameters.

    Science.gov (United States)

    Rosiaux, Y; Velghe, C; Muschert, S; Chokshi, R; Leclercq, B; Siepmann, F; Siepmann, J

    2013-11-01

    Recently, ethylcellulose/guar gum blends have been reported to provide ethanol-resistant drug release kinetics from coated dosage forms. This is because the ethanol insoluble guar gum effectively avoids undesired ethylcellulose dissolution in ethanol-rich bulk fluids. However, so far the importance of crucial formulation parameters, including the minimum amount of guar gum to be incorporated and the minimum required guar gum viscosity, remains unclear. The aim of this study was to identify the most important film coating properties, determining whether or not the resulting drug release kinetics is ethanol-resistant. Theophylline matrix cores were coated in a fluid bed with blends of the aqueous ethylcellulose dispersion "Aquacoat®ECD30" and guar gum. The polymer blend ratio, guar gum viscosity, and degree of dilution of the final coating dispersion were varied. Importantly, it was found that more than 5% guar gum (referred to the total polymer content) must be incorporated in the film coating and that the apparent viscosity of a 1% aqueous guar gum solution must be greater than 150 cP to provide ethanol-resistance. In contrast, the investigated degree of coating dispersion dilution was not found to be decisive for the ethanol sensitivity. Furthermore, all investigated formulations were long term stable, even upon open storage under stress conditions for 6 months.

  12. 77 FR 34997 - Xanthan Gum From Austria and China; Institution of Antidumping Duty Investigations and Scheduling...

    Science.gov (United States)

    2012-06-12

    ... amended. The amendments took effect on November 7, 2011. See 76 FR 61937 (Oct. 6, 2011) and the newly... COMMISSION Xanthan Gum From Austria and China; Institution of Antidumping Duty Investigations and Scheduling... from Austria and/or China of xanthan gum, provided for in subheading 3913.90.20 of the...

  13. Relative bioavailability of methadone hydrochloride administered in chewing gum and tablets

    DEFF Research Database (Denmark)

    Christrup, Lona Louring; Angelo, H.R.; Bonde, J.

    1990-01-01

    Methadone administered in chewing gum in doses of 16.7-22.6 mg to seven patients in a study using an open balanced cross-over design, was compared with 20 mg of methadone given perorally as tablets. There was no significant difference in the AUC/D obtained after administration of chewing gum...

  14. Reduction of lipid oxidation by formation of caseinate-oil-oat gum emulsions

    Science.gov (United States)

    The concentration of oat gum, though important for formation of stable emulsion, has no effect on oxidation of Omega 3 oil; this is most prominent in fish-oil based Omega 3 oil. The optimal concentration of oat gum is about 0.2% wt for emulsion stability and visual appearance. We found that concentr...

  15. Unveiling the Sources of Chromium in Pictorialist Photographs: Gum-Dichromate Process or Paper Sizing?

    DEFF Research Database (Denmark)

    Vila, Anna; Centeno, Silvia A; Kennedy, Nora W

    2015-01-01

    For this issue of Hand Papermaking devoted to paper sizing, we offer a review and extension of pertinent results obtained in our investigations of the gum-dichromate photographic process, commonly known as the gum-bichromate process.1 We have published three articles to date on our findings; this...

  16. Strategy to identify and quantify polysaccharide gums in gelled food concentrates

    NARCIS (Netherlands)

    Grün, C.H.; Sanders, P.; Burg, van der M.; Schuurbiers, E.; Adrichem, van L.; Velzen, van E.J.J.; Roo, de N.; Brunt, K.; Westphal, Y.; Schols, H.A.

    2015-01-01

    A strategy for the unambiguous identification and selective quantification of xanthan gum and locust bean gum (LBG) in gelled food concentrates is presented. DNA detection by polymerase chain reaction (PCR) showed to be a fast, sensitive, and selective method that can be used as a first screening to

  17. Determination of optimum tapping date for gum arabic production South Kordofan State, Sudan

    Institute of Scientific and Technical Information of China (English)

    Idris Musa Adam; Kamal E.M. Fadl

    2011-01-01

    Acacia senegal,the gum arabic producing tree,is the most important tree species for the livelihood of the people in South Kordofan State,Sudan.The objective of this study was to determine the optimum tapping date for gum arabic production in the study area.A randomized complete block design experiment with three replications was conducted at (Meari) area for two continuous growing seasons 2008/2009 -2009/2010.The treatments comprised six tapping dates (1 Oct,15 Oct,1Nov,15 Nov,1 Dec,and 15 Dec).Results showed highly significant differences (p < 0.001) in gum arabic yield (g\\tree) in all pickings and in the total gum yield between the tapping dates.The results also showed that tapping of trees on 15 October and 1 November gave a higher yield compared to the other dates.The highest gum yield of 1086.6 and 661.2g/tree was recorded on 15 October and 15 November,while the lowest gum yield of 297.9 g/tree was recorded when the trees were tapped on 1 October.The two highest-yield dates of tapping (15 Oct and 1 Nov) are recommended as the best time for tapping for gum arabic production in South Kordofan State.These results can be used to increase gum arabic production and farmer income in South Kordofan State.

  18. The Role of Xylitol Gum Chewing in Restoring Postoperative Bowel Activity After Cesarean Section.

    Science.gov (United States)

    Lee, Jian Tao; Hsieh, Mei-Hui; Cheng, Po-Jen; Lin, Jr-Rung

    2016-03-01

    The goal of this study was to evaluate the effects of xylitol gum chewing on gastrointestinal recovery after cesarean section. Women who underwent cesarean section (N = 120) were randomly allocated into Group A (xylitol gum), Group B (nonxylitol gum), or the control group (no chewing gum). Every 2 hr post-cesarean section and until first flatus, Groups A and B received two pellets of chewing gum and were asked to chew for 15 min. The times to first bowel sounds, first flatus, and first defecation were then compared among the three groups. Group A had the shortest mean time to first bowel sounds (6.9 ± 1.7 hr), followed by Group B (8 ± 1.6 hr) and the control group (12.8 ± 2.5 hr; one-way analysis of variance, p cesarean section, chewing gum increased participants' return of bowel activity, as measured by the appearance of bowel sounds and the passage of flatus. In this context, xylitol-containing gum may be superior to xylitol-free gum. © The Author(s) 2015.

  19. Rheological and Quality Characteristics of Taftoon Bread as Affected by Salep and Persian Gums

    Directory of Open Access Journals (Sweden)

    M. A. Sahari

    2014-01-01

    Full Text Available Effects of salep gum at concentrations of 0.5%, 1%, 3%, and 5% (w/w flour basis and the Persian gum at concentrations of 0.5%, 1%, and 3% (w/w flour basis and combination of the two gums at concentrations of 0.5% + 0.5%, 0.75% + 0.25%, and 0.25% + 0.75% on rheological properties of the wheat flour dough and quality of Taftoon bread were studied with regard to retardation of staling. Rheological (farinograph and extensograph characteristics, staling, and organoleptic evaluations were performed on the dough and the resulting Taftoon bread. Statistical results showed that the salep gum at 5% and Persian gum at 3% (w/w flour basis had a significant effect on the dough properties. Salep and Persian gums when each separately added increased and decreased dough water absorption, respectively. Both hydrocolloids increased the dough resistance to extension and decreased its extensibility. Persian gum shows dual nature in water absorption and some other baking properties. Textural studies revealed that addition of 5% salep gum (w/w flour basis reduced the bread crumb firmness and delayed the staling process of the Taftoon bread. X-ray diffraction study also confirmed this result.

  20. The influence of excessive chewing gum use on headache frequency and severity among adolescents.

    Science.gov (United States)

    Watemberg, Nathan; Matar, Manar; Har-Gil, Miki; Mahajnah, Muhammad

    2014-01-01

    Excessive gum-chewing is underreported as a headache precipitant in children and adolescents. We evaluated the influence of daily excessive gum-chewing in older children and teenagers with chronic headache, emphasizing the impact of habit discontinuation and its reintroduction. Patients with chronic headache and excessive gum-chewing were consecutively recruited and asked to fill questionnaire pertaining headache characteristics, potential triggers, family history of headaches, and gum-chewing habits. These individuals were classified into four groups depending on the number of daily hours of gum-chewing. All children discontinued chewing for 1 month, reintroduced the habit, and were reinterviewed after 2 to 4 weeks. Thirty patients (25 girls) were recruited. Median age was 16 years. Most had migraine-like headaches. Following gum-chewing discontinuation, 26 reported significant improvement, including headache resolution in 19. All 20 patients reinstituting the habit reported symptom relapse within days. Duration of headache before discontinuation and the number of daily hours of chewing had no influence on the response to habit discontinuation. Excessive daily gum-chewing may be associated with chronic headache and should get more attention in the medical literature. Physician and patient awareness of this association could have a meaningful impact on the quality of life of children and adolescents with chronic headache who chew gum excessively. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Recent advances in Rosaceae gum exudates: From synthesis to food and non-food applications.

    Science.gov (United States)

    Bouaziz, Fatma; Koubaa, Mohamed; Ellouz Ghorbel, Raoudha; Ellouz Chaabouni, Semia

    2016-05-01

    In recent years, great interest has been devoted to the development of new applications for natural gums. These molecules were used for a variety of purposes since they are chemically inert, non-toxic, less expensive, biodegradable and widely available. They represent one of the most abundant raw materials used not only in commercial food products, but also in cosmetic and pharmaceutical products. Plant gums take their advantages compared to other gums (e.g., from animal and microbial sources) mainly because of their acceptance by consumers. Despite of the well description given in literature for the features of plant gum exudates, there is a lack distinguishing the different families that are producing gums, and their potential applications. Among these gums, the ones produced by Rosaceae family (e.g., almond, apricot, cherry, peach, and plum plants) have been taking special attention. Thus, the aim of this review is to report the recent advances in Rosaceae gum exudates. An emphasis is given for the formation mechanisms of these gums, their chemical composition, functional properties and structures, beneficial properties, as well as their food/non-food applications.

  2. Effects of Chewing Different Flavored Gums on Salivary Flow Rate and pH.

    Science.gov (United States)

    Karami Nogourani, Maryam; Janghorbani, Mohsen; Kowsari Isfahan, Raha; Hosseini Beheshti, Mozhgan

    2012-01-01

    Chewing gum increases salivary flow rate (SFR) and pH, but differences in preferences of gum flavor may influence SFR and pH. The aim of this paper was to assess the effect of five different flavors of sucrose-free chewing gum on the salivary flow rate and pH in healthy dental students in Isfahan, Iran. Fifteen (7 men and 8 women) healthy dental student volunteers collected unstimulated saliva and then chewed one of five flavored gums for 6 min. The whole saliva was collected and assessed for 6 consecutive days. After unstimulated saliva was collected, stimulated saliva was collected at interval of 0-1, 1-3, and 3-6 minutes after the start of different flavored chewing gums. The SFR and salivary pH were measured. The SFR increased in all five flavored gums at 1, 3, and 6 minutes after start of chewing gums (P salivary pH. Gum flavored can affect the SFR and pH and special flavors can be advised for different individuals according to their oral conditions.

  3. Market-driven production with transaction costs outlook: Gum arabic collection systems in Senegal

    NARCIS (Netherlands)

    Mujawamariya, G.; Burger, C.P.J.; Haese, D' M.F.C.

    2015-01-01

    Low returns from marketing of non-timber forest products such as gum arabic restrict the collection of these products. A hypothesis is tested that access to good markets motivates collectors to harvest and market gum arabic. Analyses of the choice of participation in group marketing, sale price, qua

  4. Nanostructured SnO{sub 2} encapsulated guar-gum hybrid nanocomposites for electrocatalytic determination of hydrazine

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Priya [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Srivastava, Manish [Department of Physics & Astrophysics, University of Delhi, Delhi 110007 (India); Verma, Ranjana [Solar Energy Material Laboratory, Department of Energy, Tezpur University, Tezpur, Assam 784 028 (India); Kumar, Manish [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Kumar, D., E-mail: dkumar@dce.ac.in [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India); Singh, Jay, E-mail: jay_singh143@yahoo.co.in [Department of Applied Chemistry & Polymer Technology, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi 110042 (India)

    2016-01-01

    nanocomposite electrode provides an attractive matrix for impregnation of metal-oxide nanoparticles and an improved sensing platform for the electrochemical studies. - Highlights: • Sol–gel derived SnO{sub 2} nanoparticles encapsulated into gaur gum matrix • Utilizes organic–inorganic hybrid nanocomposite for determination of hydrazine • Cyclic voltammetry studies were used to evaluate kinetic parameters • SnO{sub 2}-Guar gum nanocomposite an attractive matrix for the electrochemical studies.

  5. Comparative Study on Rheology of Welan Gum and Xanthan Gum%韦兰胶与黄原胶流变性比较研究

    Institute of Scientific and Technical Information of China (English)

    吉武科; 赵双枝; 严希海; 徐桂英

    2011-01-01

    In this paper,rheology (including viscoelasticity,temperature stability,and salt tolerance) of we-lan gum and xanthan gum was compared. The results showed that,compared with xanthan gum, welan gum had better viscoelasticity at same concentration,more stability at low temperature,and better salt tolerance.%对韦兰胶和黄原胶的流变性(包括粘弹性、温度稳定性和耐盐性)进行了比较研究.结果表明,与黄原胶相比,韦兰胶在相同浓度下具有更好的粘弹性、在低温下更稳定、具有较好的耐盐性.

  6. Evaluation of alternatives to guar gum as tackifiers for hydromulch and as clumping agents for biodegradable cat litter

    Science.gov (United States)

    Guar gum is currently the principal gum used as a tackifier for hydromulch used in erosion control, and as a clumping agent in biodegradable cat litters. Due to recent severe price increases for guar gum, cheaper alternatives are being investigated. We examined several alternatives, including xanth...

  7. Photo-induced Synthesis and Characterization of Poly(methyl methacrylate) Grafted Sodium Salt of Partially Carboxymethylated Guar Gum

    Institute of Scientific and Technical Information of China (English)

    J.H.Trivedi; M.D.Thaker; H.C.Trivedi

    2014-01-01

    Photo-induced graft copolymerization of methyl methacrylate (MMA) onto sodium salt of partially carboxymethylated guar gum (Na-PCMGG,DS =0.291) was carried out in an aqueous medium using ceric ammonium nitrate (CAN) as photoinitiator to synthesize a novel graft copolymer,Na-PCMGG-g-PMMA,which may find its potential application as a metal adsorbent.The influences of synthesis variables such as concentrations of photoinitiator (CAN),nitric acid and monomer (MMA) as well as reaction time,temperature and amount of substrate on the grafting yields were studied and the reaction conditions for optimum photo-grafting were evaluated.At optimum concentration,the maximum values of the grafting yields achieved were G =271.61% and GE =63.89%.The experimental results were found to be in very good agreement with the proposed kinetic scheme.The photo-graft copolymerization of MMA onto Na-PCMGG (DS =0.291) was also carried out in the presence and absence of ultraviolet radiation for studying the efficiency of the photoinitiator.The influence of carboxymethyl groups introduced onto the guar gum molecules with regard to its behavior towards ultra-violet radiation induced grafting with MMA was also investigated.Photo-grafting process was confirmed and the products were characterized with the help of the spectroscopic (1H-NMR and FTIR) and SEM techniques.

  8. In vivo mucoadhesive strength appraisal of gum Manilkara zapota

    Directory of Open Access Journals (Sweden)

    Singh Sudarshan

    2015-09-01

    Full Text Available The mucilage (MMZ extracted from the seeds of Manilkara zapota(Linn. P. Royen syn. using maceration techniques was evaluated for mucoadhesive strength by various in vitro and in vivo methods. The result showed that mucoadhesive strength of seeds mucilage have comparable property toward natural and synthetic polymers such as Guar Gum and hydroxyl propyl methyl cellulose (HPMC E5LV under the experimental conditions used in this study. Briefly, it could be concluded that the seed mucilage of Manilkara zapota can be used as a pharmaceutical excipient in oral mucoadhesive drug delivery systems. Further, it may be appropriate to study the changes in these properties after chemical modifications.

  9. Rheological properties of gelatin, carrageenan and locust bean gum mixtures

    OpenAIRE

    Jones, Guy Matthew John

    2004-01-01

    This thesis reports data on blends of carrageenan (0.3%w/w) and locust bean gum (0.3%w/w) in the presence of biopolymers, particularly gelatin of varying concentration. Particular attention is given to their behaviour on autoclaving since this is relevant to one of the most important applications of these materials as gelling agents in canned meat products. It was shown there is such 3% gelatin could be found in the gelling system as a result of from collagen in the meat. Gelatin at this ...

  10. Young stars of low mass in the Gum nebula

    Science.gov (United States)

    Graham, J. A.; Heyer, Mark H.

    1989-01-01

    Observations are presented for four recently formed stars in the vicinity of the Gum nebula which are heavily obscured by surrounding dust and are associated with small reflection nebulae. HH46 is the only currently active star of the sample, and it is found to have a spectral type in the range of late G-early K, with superimposed emission lines of H-alpha, Ca II, Fe I, Fe II, and weak He I at near zero velocities. It is suggested that the observed scenario of low-mass stars in an older massive star environment may be analogous to the circumstances surrounding the birth of the sun.

  11. Metal forming and lubrication

    DEFF Research Database (Denmark)

    Bay, Niels

    2000-01-01

    Lubrication is essential in most metal forming processes. The lubricant film has two basic functions, [1]: i. to separate the work piece and tool surfaces and ii. to cool the workpiece and the tool. Separation of the two surfaces implies lower friction facilitating deformation and lowering the tool...... deformation step to avoid overheating and breakdown of the lubricant....

  12. Purification of cress seed (Lepidium sativum) gum: A comprehensive rheological study

    DEFF Research Database (Denmark)

    Razmkhah, Somayeh; Razavi, Seyed Mohammad Ali; Mohammadifar, Mohammad Amin

    2016-01-01

    In this paper, the effects of different purification methods (ethanol (sample E), isopropanol (sample I) and ethanol-isopropanol (sample EI)) on intrinsic viscosity, steady and dynamic rheological properties of cress seed gum were investigated. The gum dispersions exhibited viscoelastic properties......, the storage modulus (G′) was higher than the loss modulus (G″), and mechanical spectra of the crude and purified cress seed gums were classified as weak gels. The purified samples had stronger and more elastic network structure than the crude gum (CSG) and the gel network got stronger along the series of I......, EI and E. All the gum dispersions indicated shear-thinning behavior and the viscosity of the samples followed the order of E > EI > I > CSG. Herschel-Bulkley model was the best model to describe steady shear flow behavior and Arrhenius-type model was also applied to describe the effect of temperature...

  13. Prospective of guar gum and its derivatives as controlled drug delivery systems.

    Science.gov (United States)

    Prabaharan, M

    2011-08-01

    Guar gum is a non-ionic polysaccharide that is found abundantly in nature and has many properties desirable for drug delivery applications. However, due to its high swelling characteristics in aqueous solution, the use of guar gum as delivery carriers is limited. Guar gum can be modified by derivatization, grafting and network formation to improve its property profile for a wide spectrum of biomedical applications. This review article is aimed at focusing the recent efforts and developments on guar gum and its derivatives as colon-specific, antihypertensive, protein and transdermal drug delivery systems. Based on the literatures reviewed, it is concluded that guar gum and its derivatives in the various forms such as coatings, matrix tablets, hydrogels and nano/microparticles can be exploited as potential carriers for targeted drug delivery.

  14. Optimization of enzymatic hydrolysis of guar gum using response surface methodology.

    Science.gov (United States)

    Mudgil, Deepak; Barak, Sheweta; Khatkar, B S

    2014-08-01

    Guar gum is a polysaccharide obtained from guar seed endosperm portion. Enzymatically hydrolyzed guar gum is low in viscosity and has several health benefits as dietary fiber. In this study, response surface methodology was used to determine the optimum conditions for hydrolysis that give minimum viscosity of guar gum. Central composite was employed to investigate the effects of pH (3-7), temperature (20-60 °C), reaction time (1-5 h) and cellulase concentration (0.25-1.25 mg/g) on viscosity during enzymatic hydrolysis of guar (Cyamopsis tetragonolobus) gum. A second order polynomial model was developed for viscosity using regression analysis. Results revealed statistical significance of model as evidenced from high value of coefficient of determination (R(2) = 0.9472) and P guar gum as potential source of soluble dietary fiber for human health benefits.

  15. Efficacy of acute administration of nicotine gum in relief of cue-provoked cigarette craving.

    Science.gov (United States)

    Shiffman, Saul; Shadel, William G; Niaura, Raymond; Khayrallah, Moise A; Jorenby, Douglas E; Ryan, Charles F; Ferguson, Clifford L

    2003-04-01

    Acute cravings, often provoked by exposure to smoking cues, appear to be important triggers for smoking relapse. Relief of acute craving may therefore be an important step in preventing relapse. This study was undertaken to assess the effectiveness of nicotine gum in relieving acute craving. A multi-center, randomized, placebo-controlled study was conducted with smokers ( n=296) who quit by using either active or inactive gum for 3 days. On their third day of abstinence, smokers participated in a laboratory session in which they were exposed to a provocative smoking cue, chewed active or inactive gum, and then rated their craving at 5-min intervals for 35 min. Craving initially decreased in both groups. After 15 min, however, the smokers using active nicotine gum experienced significantly greater craving reductions. These results suggest that nicotine gum can effectively reduce acute craving following exposure to smoking cues.

  16. Selective depression behavior of guar gum on talc-type scheelite flotation

    Science.gov (United States)

    Zhang, Yong-zhong; Gu, Guo-hua; Wu, Xiang-bin; Zhao, Kai-le

    2017-08-01

    The depression behavior and mechanism of guar gum on talc-type scheelite flotation were systematically investigated by flotation experiments, adsorption tests, zeta-potential measurements, and infrared spectroscopic analyses. The flotation results for monominerals, mixed minerals, and actual mineral samples indicated that guar gum exhibited much higher selective depression for talc than for scheelite. Bench-scale closed-circuit tests showed that a tungsten concentrate with a WO3 grade of 51.43% and a WO3 recovery of 76.18% was obtained. Adsorption tests, zeta-potential measurements, and infrared spectral analyses confirmed that guar gum absorbed more strongly onto the talc surface than onto the scheelite surface because of chemisorption between guar gum and talc. This chemisorption is responsible for the guar gum's highly selective depression for talc and small depression for scheelite. The flotation results provide technical support for talc-type scheelite flotation.

  17. [Gum-like exudate from Laguncularia racemosa (white mangrove) as culture media for fungi].

    Science.gov (United States)

    Mesa, L M; León-Pinto, G

    1993-01-01

    Morphological studies of eight species of fungus: Aspergillus flavus Microsporum canis, Epidermophyton floccosum, Curvularia lunata, Cladosporium carrionii, Natrassia mangífera (Edo. Scytalidium), Sporotrix schenckii y Rhizophus oligosporus, which belong to families Mucedinaceae, Dematiaceae and Mucoraceae have been carried out in support medium based in gum exudate from Laguncularia racemosa (mangle blanco). This native polimer contains galactose, arabinose, rhamnose, uronic acid and proteins. Nitrogen calcium and magnesium are microconstituents of the gum. An economical substrate which contained gum exudate (4%) and agar (1.5%) was used in these studies. The results obtained showed that gum exudate-agar medium (EGA) permits an adequate identification of the studied species, therefore, it is a possible substitute for Sabouraud. It is important to know that the gum exudate is a natural product, economical and easy to obtain.

  18. Synthesis, physico-chemical and biomedical applications of sulfated Aegle marmelos gum: Green chemistry approach

    Directory of Open Access Journals (Sweden)

    Manish Jindal

    2017-05-01

    Full Text Available The present investigation was aimed at obtaining a sulfated derivative of gum obtained from partially ripe fruits of Aegle marmelos employing the ultrasonication technique. Elemental analysis and FTIR-ATR studies confirmed successful sulfation. The molarity of sulfuric acid exerted maximum influence on the degree of substitution followed by reaction temperature and reaction time. The sulfated derivative showed higher swelling in both acidic and alkaline pH as compared to the unmodified gum. It also possessed higher negative zeta potential, higher viscosity, work of shear, firmness, consistency, cohesiveness and index of viscosity as compared to both unmodified gum as well as sodium alginate. Sulfated derivative was superior to unmodified gum and sodium alginate in terms of antimicrobial and anticoagulant activities. The sulfated sample appears to be a potential substitute over the unmodified gum sample and sodium alginate for modulating the physicochemical properties of food and drug release dosage forms.

  19. Experimental and theoretical studies of xanthan gum and its graft co-polymer as corrosion inhibitor for mild steel in 15% HCl

    Energy Technology Data Exchange (ETDEWEB)

    Biswas, Amrita; Pal, Sagar; Udayabhanu, G., E-mail: g_udayabhanu@hotmail.com

    2015-10-30

    Highlights: • Xanthan gum and its graft co-polymer used as corrosion inhibitors for mild steel in 15% HCl. • Electrochemical and weight loss studies give comparable corrosion rates. • Both the inhibitors are mixed type in nature. • Modified graft co-polymer is a more effective corrosion inhibitor. • Theoretical calculations taking monomer units of the polymer support the experimental results. - Abstract: Xanthan gum (XG) and its graft co-polymer have been investigated as corrosion inhibitors for mild steel in 15% HCl. Gravimetric analysis, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were employed for investigating the effectiveness of these inhibitors. Results indicate that both the inhibitors are of mixed type and follow Langmuir adsorption isotherm. Scanning electron microscopy (SEM) study also confirmed the protection of the metal surface by XG and xanthan gum-graft-poly(acrylamide) (XG-g-PAM). Theoretical calculations using Density Functional Theory (DFT) were used to establish the correlation between the structure and corrosion protection efficiencies.

  20. Guar gum solutions for improved delivery of iron particles in porous media (Part 1): Porous medium rheology and guar gum-induced clogging

    Science.gov (United States)

    Gastone, Francesca; Tosco, Tiziana; Sethi, Rajandrea

    2014-10-01

    The present work is the first part of a comprehensive study on the use of guar gum to improve delivery of microscale zero-valent iron particles in contaminated aquifers. Guar gum solutions exhibit peculiar shear thinning properties, with high viscosity in static conditions and lower viscosity in dynamic conditions: this is beneficial both for the storage of MZVI dispersions, and also for the injection in porous media. In the present paper, the processes associated with guar gum injection in porous media are studied performing single-step and multi-step filtration tests in sand-packed columns. The experimental results of single-step tests performed by injecting guar gum solutions prepared at several concentrations and applying different dissolution procedures evidenced that the presence of residual undissolved polymeric particles in the guar gum solution may have a relevant negative impact on the permeability of the porous medium, resulting in evident clogging. The most effective preparation procedure which minimizes the presence of residual particles is dissolution in warm water (60 °C) followed by centrifugation (procedure T60C). The multi-step tests (i.e. injection of guar gum at constant concentration with a step increase of flow velocity), performed at three polymer concentrations (1.5, 3 and 4 g/l) provided information on the rheological properties of guar gum solutions when flowing through a porous medium at variable discharge rates, which mimic the injection in radial geometry. An experimental protocol was defined for the rheological characterization of the fluids in porous media, and empirical relationships were derived for the quantification of rheological properties and clogging with variable injection rate. These relationships will be implemented in the second companion paper (Part II) in a radial transport model for the simulation of large-scale injection of MZVI-guar gum slurries.

  1. KARAKTERISTIK EMULSI SANTAN DAN MINYAK KEDELAI YANG DITAMBAH GUM ARAB DAN SUKROSA ESTER [Emulsion Characteristics of Coconut Milk and Soybean Oil Added with Gum Arabic and Sucrose Ester

    Directory of Open Access Journals (Sweden)

    Laksmi Hartayanie

    2015-07-01

    Full Text Available High saturated fatty acid content in coconut milk can be reduced by adding unsaturated fat. Pretreatment such as pasteurisation, homogenization or stabilizer and emulsifier addition are essential to prevent emulsion deterioration that could happen in few hours. This study aimed to determine the most appropriate combination of gum arabic and sucrose ester to produce good emulsion stability based on its physical and chemical characteristics. Furthermore this study also aimed to determine correlation between creaming index and other characteristics of coconut milk emulsion. Emulsion stability of mixed coconut milk in sterile glass bottles was observed for 7 days under 23-24°C. Stabilizer and emulsifier added were gum arabic and sucrose ester in five combinations, i.e. 6% gum arabic, 0.3% sucrose ester, 6% gum arabic + 0.3% sucrose ester, 3% gum arabic + 0.15% sucrose ester and 4.5% gum arabic + 0.225% sucrose ester. The physical characteristics evaluated were creaming index, total color change, viscosity and droplet distribution, while the chemical characteristics observed included pH, TBA value, and protein content. Data were analyzed by One Way Anova at 95% significant level to determine the differences among treatments. Bivariate Pearson Correlation was used in order to determine the interaction among sample characteristics. The data showed that, gum arabic and sucrose ester can maintain the emulsion stability. A combination of 4.5% gum arabic and 0.225% sucrose ester provided the best physicochemical characteristics with the lowest creaming index and decreased viscosit, and uniform droplet distribution.

  2. Evaluation of guar gum derivatives as gelling agents for microbial culture media.

    Science.gov (United States)

    Gangotri, Waikhom; Jain-Raina, Ruchi; Babbar, Shashi B

    2012-05-01

    Guar gum, a galactomannan, has been reported to be an inexpensive substitute of agar for microbial culture media. However, its use is restricted probably because of (1) its highly viscous nature even at high temperatures, making dispensing of the media to Petri plates difficult and (2) lesser clarity of the guar gum gelled media than agar media due to impurities present in guar gum. To overcome these problems, three guar gum derivatives, carboxymethyl guar, carboxymethyl hydroxypropyl guar and hydroxypropyl guar, were tested as gelling agents for microbial growth and differentiation. These were also evaluated for their suitability for other routine microbiological methods, such as, enumeration, use of selective and differential media, and antibiotic sensitivity test. For evaluation purpose, growth and differentiation of eight fungi and eight bacteria grown on the media gelled with agar (1.5%), guar gum (4%) or one of the guar gum derivatives (4%), were compared. All fungi and bacteria exhibited normal growth and differentiation on all these media. Generally, growth of most of the fungi was better on guar gum derivatives gelled medium than on agar medium. The enumeration carried out for Serratia sp. and Pseudomonas aeruginosa by serial dilution and pour plate method yielded similar counts in all the treatments. Likewise, the selective succinate medium, specific for P. aeruginosa, did not allow growth of co-inoculated Bacillus sp. even if gelled with guar gum derivatives. The differential medium, Congo red mannitol agar could not differentiate between Agrobacterium tumefaciens and Rhizobium meliloti on color basis, if gelled with guar gum or any of its derivatives However, for antibiotic sensitivity tests for both Gram-positive and -negative bacteria, guar gum and its derivatives were as effective as agar.

  3. Assessment of ferula Gummosa gum as a binding agent in tablet formulations.

    Science.gov (United States)

    Enauyatifard, Reza; Azadbakht, Mohammad; Fadakar, Yousef

    2012-01-01

    Ferula gummosa Boiss. (Apiaceae) is one of the natural plants of Iran. The whole plant, but especially the root, contains the gum resin "galbanum". A study of the comparative effects of galbanum gum and two standard binding agents--polyvinylpyrolidone and acacia--on characteristics of acetaminophen and calcium carbonate compacts was made. The Ferula gummosa gum was extracted and its swelling index was determined. Acetaminophen and calcium carbonate granules were prepared using the wet granulation method and were evaluated for their micromeritics and flow properties, while the compacts were evaluated for mechanical properties using the hardness, tensile strength and friability. The drug release from acetaminophen compacts were assessed using dissolution studies. The dry powder of Ferula gummosa gum resin (galbanum) yielded 14% w/w of gum using distilled water as extraction solvent. The swelling index indicates that galbanum gum swelled to about 190% of initial volume in distilled water. Thus galbanum gum has the ability to hydrate and swells in cold water. The bulk and tapped densities and the interspace porosity (void porosity) percent of the granules prepared with different binders showed significant difference. The hardness and tensile strength of acetaminophen and calcium carbonate compacts containing various binders was of the rank order PVP > acacia > galbanum gum (p tablets containing the different binders was PVP> galbanum gum > acacia. The results of mechanical properties of acetaminophen and calcium carbonate compacts indicate that galbanum gum could be useful to produce tablets with desired mechanical characteristics for specific purposes, and could be used as an alternative substitute binder in pharmaceutical industries.

  4. Deformations of crystal frameworks

    CERN Document Server

    Borcea, Ciprian S

    2011-01-01

    We apply our deformation theory of periodic bar-and-joint frameworks to tetrahedral crystal structures. The deformation space is investigated in detail for frameworks modelled on quartz, cristobalite and tridymite.

  5. Deformed General Relativity

    CERN Document Server

    Bojowald, Martin

    2013-01-01

    Deformed special relativity is embedded in deformed general relativity using the methods of canonical relativity and loop quantum gravity. Phase-space dependent deformations of symmetry algebras then appear, which in some regimes can be rewritten as non-linear Poincare algebras with momentum-dependent deformations of commutators between boosts and time translations. In contrast to deformed special relativity, the deformations are derived for generators with an unambiguous physical role, following from the relationship between canonical constraints of gravity with stress-energy components. The original deformation does not appear in momentum space and does not give rise to non-locality issues or problems with macroscopic objects. Contact with deformed special relativity may help to test loop quantum gravity or restrict its quantization ambiguities.

  6. 野油菜黄单胞菌中gumD基因的过表达对产黄原胶的影响%Effect of by overexpressing gumD in Xanthomonas campestris on the xanthan gum

    Institute of Scientific and Technical Information of China (English)

    王桂兰; 张晓元; 陈晓燕; 朱希强; 凌沛学

    2012-01-01

    Purpose To improve the yield and quality of xanthan gum by overexpressing gumD in Xanthomonas campestris 58 ( Xc58 ). Methods By PCR amplification, plasmid construction, triparental conjugation and other methods,pBBR-gumD was transformed into the original strain Xc58. Results Compared with Xc58,the recombinant strain Xc58-D has increased by 11. 19% in the yield of xanthan gum, by 6.31% increased in viscosity,by 20. 21 % increased in molecular weight,and by 77. 07% increased in acetyl content, but 6. 34% decreased in pyruvate content. Conclusion The recombinant strain has a higher yield and improves the quality of xanthan gum.%目的 在野油菜黄单胞茵58(Xc58)中过量表达产胶基因gumD,提高黄原胶发酵产量和质量.方法 通过PCR扩增、重组质粒构建、三亲本接合等方法,将重组质粒pBBR-gumD转入原始茵Xc58.结果 工程茵与原始茵相比,黄原胶产量提高11.19%,黏度提高6.31%,重均分子质量提高20.21%,乙酰基含量提高77.07%,丙酮酸含量下降6.34%.结论 改造后的菌株的黄原胶发酵产量和质量都较原始茵株有所提高.

  7. Effects of metal-inlay thickness in polyethylene cups with metal-on-metal bearings.

    NARCIS (Netherlands)

    Verdonschot, N.J.J.; Vena, P.; Stolk, J.; Huiskes, R.

    2002-01-01

    A way to prevent polyethylene wear in total hip replacements is to use metal-on-metal bearings. The cup design of these bearings may be a metal inlay in a polyethylene cup. However, these metal inlays are relatively thin and may deform on loading. The purpose of the current study was to determine wh

  8. Rheological and drag reduction properties of hydroxypropyl xanthan gum solutions☆

    Institute of Scientific and Technical Information of China (English)

    Meng Tian; Bo Fang; Leiping Jin; Yongjun Lu; Xiaohui Qiu; Hao Jin; Kejing Li

    2015-01-01

    Hydroxypropyl xanthan gum (HXG) was prepared from xanthan gum (XG) and propylene oxide under alkaline condition. Rheological and drag reduction properties of different concentrations of aqueous HXG and XG solution were studied. The micro-structure network of HXG and XG solutions was investigated by Cryo-FESEM. The re-sults showed that HXG and XG solutions could exhibit shear thinning property. The apparent viscosity of 6 g·L−1 HXG solution was 1.25 times more than that of 6 g·L−1 XG solution. The storage modulus G′and the loss modulus G″of HXG solutions were greater than those of XG solutions, and thixotropic and viscoelastic prop-erties were more significant in HXG solutions. The HXG and XG solutions reduced the pressure drop of straight pipe, and the maximum drag reduction of 1 g·L−1 HXG and XG in smooth tube reached 72.8%and 68.1%, respec-tively. Drag reduction rate was increased as the concentration increased. The HXG solution may become a new polymeric drag reducer.

  9. Synthesis and characterization of guar gum templated hybrid nano silica.

    Science.gov (United States)

    Singh, V; Singh, S K; Pandey, S; Sanghi, R

    2011-08-01

    The objective of the present study was the fabrication of green adsorbent hybrids for which native guar gum was used as template to polymerize tetraethoxysilane. The properties and performances of the hybrids could be tailored by using varying molecular sizes of the partially depolymerized guar gum templates of various molecular sizes as control. Zn(II) uptake from aqueous solution was used as a criterion for evaluating the adsorbent efficiency. The optimum material (H4) in terms of maximum Zn(II) uptake, was obtained when the template size used was 375 kDa at a calcination temperature of 700°C. H4 was also evaluated for Ca(II), Mg(II), Cd(II) and Hg(II) adsorption. To explore the other applicability areas, the hybrids have been extensively characterized using FTIR, XRD, TGA-DTA, PL, SEM, TEM and BET analyses. H4 was found to be as efficient as previously reported vinyl modified-silica nanohybrids. It had a high surface area (264 m(2)/g) with silica nanoparticles in the size range of 90-140 nm. Being thermally very stable and photoluminescent, the material can be potentially used for many biological, medical and environmental applications.

  10. Electrospun fibers based on Arabic, karaya and kondagogu gums.

    Science.gov (United States)

    Padil, Vinod Vellora Thekkae; Senan, Chandra; Wacławek, Stanisław; Černík, Miroslav

    2016-10-01

    Nanofibers of natural tree polysaccharides based on three gums namely Arabic (GA), karaya (GK) and kondagogu (KG) have been prepared for the first time using electrospinning. Electrospinning solutions were prepared by mixing gum solutions of GA, GK & KG with eco-friendly polymers such as polyvinyl alcohol (PVA) or polyethylene oxide (PEO). The present study focuses on the effect of electrospinning blended solutions of GA, GK or KG with PVA or PEO, additives which influence system parameters and process parameters. This has important effects on the electrospinning process and the resulting fibers whose morphology and physicochemical properties were evaluated. The mass ratios of 70:30 to 90:10 for PVA: GA, PVA: GK and PVA: KG were observed to establish an optimum blend solution ratio in order to fabricate uniform beadless nanofibers with an average diameter of 240±50, 220±40 and 210±30nm, respectively. Various structural and physicochemical properties of the electrospun fibers were investigated. Furthermore, the comparisons of various functionalities of the untreated and plasma treated electrospun fibers were assessed. The methane plasma treated nanofibers were shown to be of extremely specific surface area, improved water contact angle, high surface porosity and roughness and superior hydrophobic properties compared to untreated fibers.

  11. Hypolipidemic activity of gum ghatti of Anogeissus latifolia

    Directory of Open Access Journals (Sweden)

    K.M.M Parvathi

    2009-01-01

    Full Text Available Cardiovascular diseases are becoming an increasing problem worldwide and hypercholesterolemia has been correlated for coronary heart diseases. Currently available hypolipidemic drugs have been associated with number of side effects. Herbal treatment for hyperlipidemia poses no side effects and is relatively cheap and locally available. In view of this, the present study was carried out to investigate the effect of gum ghatti of Anogeissus lalifolia on serum lipid levels of albino rats. Rats were made hyperlipidemic by the oral administration of cholesterol (400mg/kg body weight/day along with cholic acid (50mg/kg in coconut oil. The hypolipidemic effect was compared with control. The rats were divided into six groups of six animals each. In atherogenic diet induced hyperlipidemic model, the rats receiving treatment with gum ghatti at 250 mg/kg dosage showed significant reduction in serum triglyceride (82.75±0.63 only and there was no significant changes either in serum total cholesterol or elevation in HDL. Whereas, at 500 and 750 mg/kg dosage showed significant reduction in serum total cholesterol (72.85±0.60, 68.17±0.95 and serum triglyceride (78.92±0.34, 75.93±1.05. Further, the 750 mg/kg dose has also exhibited significant elevation in high density lipoprotein cholesterol (41.13±0.37.

  12. Structural characterization of mesquite (Prosopis velutina) gum and its fractions.

    Science.gov (United States)

    López-Franco, Yolanda L; de la Barca, Ana M Calderón; Valdez, Miguel A; Peter, Martin G; Rinaudo, Marguerite; Chambat, Gérard; Goycoolea, Francisco M

    2008-08-11

    Structural and physicochemical characteristics of mesquite gum (from Prosopis velutina) were investigated using FT-IR spectroscopic, mass spectrometric and chromatographic methods. Four fractions (F-I, F-IIa, F-IIb and F-III) were isolated by hydrophobic interaction chromatography. The samples were characterized and analyzed for their monosaccharide and oligomers composition by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). L-Arabinose (L-Ara) and D-galactose (D-Gal) were found as the main carbohydrate constituent residues in the polysaccharides from mesquite gum and their ratio (L-Ara/D-Gal) varied within the range 2.54 to 3.06 among the various fractions. Small amounts of D-glucose (D-Glc), D-mannose (D-Man) and D-xylose (D-Xyl) were also detected, particularly in Fractions IIa, IIb and III. Infrared spectroscopy identified polysaccharides and protein in all the samples. Data from mass spectrometry (MALDI-TOF MS) was consistent with the idea that the structure corresponding to the periphereal chains of Fraction I is predominantly a chain of pentoses attached to uronic acid.

  13. Shape Function-Based Estimation of Deformation with Moving Cameras Attached to the Deforming Body

    Science.gov (United States)

    Jokinen, O.; Ranta, I.; Haggrén, H.; Rönnholm, P.

    2016-06-01

    The paper presents a novel method to measure 3-D deformation of a large metallic frame structure of a crane under loading from one to several images, when the cameras need to be attached to the self deforming body, the structure sways during loading, and the imaging geometry is not optimal due to physical limitations. The solution is based on modeling the deformation with adequate shape functions and taking into account that the cameras move depending on the frame deformation. It is shown that the deformation can be estimated even from a single image of targeted points if the 3-D coordinates of the points are known or have been measured before loading using multiple cameras or some other measuring technique. The precision of the method is evaluated to be 1 mm at best, corresponding to 1:11400 of the average distance to the target.

  14. Strain-rate and temperature dependent material properties of Agar and Gellan Gum used in biomedical applications.

    Science.gov (United States)

    Schiavi, Alessandro; Cuccaro, Rugiada; Troia, Adriano

    2016-01-01

    Agar and Gellan Gum are biocompatible polymers extensively used in several fields of tissue engineering research (e.g. tissue replacement, tissue support, tissue mimicking), due to their mechanical behaviour effectively representative of actual biological tissues. Since mechanical properties of artificial tissues are related to biocompatibility and functionality of medical implants and significantly influence adhesion, growth and differentiation of cells in tissue-engineering scaffolds, an accurate characterization of Young׳s modulus and relaxation time processes is needed. In this study, the strain-rate and temperature dependent material properties of Agarose and one among the numerous kind of Gellan Gum commercially available, known as Phytagel(®), have been investigated. Nine hydrogel samples have been realized with different mechanical properties: the first one Agar-based as a reference material, the further eight samples Gellan Gum based in which the effect of dispersed solid particles like kieselguhr and SiC, as enhancing mechanical properties factors, have been investigated as a function of concentration. Stress-strain has been investigated in compression and relaxation time has been evaluated by means of the Kohlrausch-Williams-Watts time decay function. Mechanical properties have been measured as a function of temperature between 20 °C and 35 °C and at different strain rates, from ~10(-3)s(-1) and ~10(-2)s(-1) (or deformation rate from ~0.01 mms(-1) to ~0.1 mms(-1)). From experimental data, the combined temperature and strain-rate dependence of hydrogels Young׳s modulus is determined on the basis of a constitutive model. In addition to a dependence of Young׳s modulus on temperature, a remarkable influence of strain-rate has been observed, especially in the sample containing solid particles; in same ranges of temperature and strain-rate, also relaxation time variations have been monitored in order to identify a possible dependence of damping

  15. Rheology of dispersions of xanthan gum, locust bean gum and mixed biopolymer gel with silicon dioxide nanoparticles.

    Science.gov (United States)

    Kennedy, Jordan R M; Kent, Katherine E; Brown, Jennifer R

    2015-03-01

    Mixed xanthan gum (XG) and locust bean gum (LBG) biopolymers form thermally reversible gels of interest in tissue engineering and drug delivery. 1% solutions of XG, LBG and 1:1 ratio XG/LBG mixed gels (LX) containing silicon dioxide (SiO2) nanoparticles were rheologically characterized with respect to nanoparticle concentration and temperature. 10% nanoparticles in XG created larger domains of associated polymer, resulting in enhanced viscosity and viscoelastic moduli. In LBG with 10% particles, transient viscosity and a gel-sol transition occurred due to particle bridging and aggregation. In the LX gel, 10% SiO2 particles caused an increase in elasticity. When ramping temperature from 25°C to 85°C, the complex modulus for all solutions containing 10% SiO2 was relatively constant, indicating that nanoparticles counteracted the effect of temperature on the material properties. Understanding the influence of nanoparticle loading on material properties is necessary for biopolymer material development where property prediction and control are critical.

  16. Native and structurally modified gum arabic: exploring the effect of the gum's microstructure in obtaining electroactive nanoparticles.

    Science.gov (United States)

    Cornelsen, Patricia A; Quintanilha, Ronaldo C; Vidotti, Marcio; Gorin, Philip A J; Simas-Tosin, Fernanda F; Riegel-Vidotti, Izabel C

    2015-03-30

    Electroactive nanoparticles combining gum arabic (GA) and polyaniline (PANI) were prepared by chemical synthesis. The gum consists of highly branched anionic polysaccharides with some protein content. GA was structurally modified by Smith controlled degradation, in order to reduce its degree of branching (GAD), aiming the elucidation of the relationship between the structure and the properties of complex polysaccharides. The modification was studied by SEC, GC-MS, (13)C NMR and colorimetric methods. GAD has lower molecular mass, lower degree of branching and lower uronic acid content. Besides it is enriched in galactose and protein when compared with GA. The obtained composites (GA-PANI and GAD-PANI) were thoroughly characterized. Although the use of both polysaccharides (GA and GAD) produced highly stable electroactive nanoparticles, the best combination of properties was achieved for GA-PANI. The sample GAD was not able to prevent the occurrence of crosslinking between PANI chains, possibly due to its lower microstructural complexity which diminishes the occurrence of hydrogen bonds between the polymers.

  17. Chemical and Functional Properties of Chia Seed (Salvia hispanica L. Gum

    Directory of Open Access Journals (Sweden)

    Maira Rubi Segura-Campos

    2014-01-01

    Full Text Available Chia (Salvia hispanica L. constitutes a potential alternative raw material and ingredient in food industry applications due to its dietary fiber content. Gum can be extracted from its dietary fiber fractions for use as an additive to control viscosity, stability, texture, and consistency in food systems. The gum extracted from chia seeds was characterized to determine their quality and potential as functional food additives. The extracted chia gum contained 26.2% fat and a portion was submitted to fat extraction, producing two fractions: gum with fat (FCG and gum partly defatted (PDCG. Proximal composition and physicochemical characterization showed these fractions to be different (P<0.05. The PDCG had higher protein, ash, and carbohydrates content than the FCG, in addition to higher water-holding (110.5 g water/g fiber and water-binding capacities (0.84 g water/g fiber. The FCG had greater oil-holding capacity (25.7 g oil/g fiber and water absorption capacity (44 g water/g fiber. In dispersion trials, the gums exhibited a non-Newtonian fluid behavior, specifically shear thinning or pseudoplastic type. PDCG had more viscosity than FCG. Chia seed is an excellent natural source of gum with good physicochemical and functional qualities, and is very promising for use in food industry.

  18. Purification of cress seed (Lepidium sativum) gum: Physicochemical characterization and functional properties.

    Science.gov (United States)

    Razmkhah, Somayeh; Mohammadifar, Mohammad Amin; Razavi, Seyed Mohammad Ali; Ale, Marcel Tutor

    2016-05-01

    The aim of the present study was to investigate the effects of different purification methods (ethanol, isopropanol and ethanol-isopropanol) on the physicochemical and functional characteristics of cress seed gum. Sugar composition and molecular weight of the samples varied significantly. All the purification methods reduced ash and protein content and molecular weight of cress seed gum. The main decomposition of the purified samples started above 200°C and initial decomposition temperature of the crude gum was 190.21°C. DSC thermograms of the purified gums showed two exothermic events at 257.81-261.95°C and 302.46-311.57°C. Crude gum displayed an exothermic peak at 259.42°C. Sample I (purified using isopropanol) imparted the best surface activity among the purified samples as it had the highest protein and uronic acid contents and the lowest Mw. All the purification methods could improve emulsifying properties of cress seed gum and there was no significant difference among the purified samples. Crude gum showed the lowest foaming properties, while samples I and E (purified using ethanol) showed the highest foaming capacity and foam stability, respectively.

  19. Chewing gum: cognitive performance, mood, well-being, and associated physiology.

    Science.gov (United States)

    Allen, Andrew P; Smith, Andrew P

    2015-01-01

    Recent evidence has indicated that chewing gum can enhance attention, as well as promoting well-being and work performance. Four studies (two experiments and two intervention studies) examined the robustness of and mechanisms for these effects. Study 1 investigated the acute effect of gum on mood in the absence of task performance. Study 2 examined the effect of rate and force of chewing on mood and attention performance. Study 3 assessed the effects of chewing gum during one working day on well-being and performance, as well as postwork mood and cognitive performance. In Study 4, performance and well-being were reported throughout the workday and at the end of the day, and heart rate and cortisol were measured. Under experimental conditions, gum was associated with higher alertness regardless of whether performance tasks were completed and altered sustained attention. Rate of chewing and subjective force of chewing did not alter mood but had some limited effects on attention. Chewing gum during the workday was associated with higher productivity and fewer cognitive problems, raised cortisol levels in the morning, and did not affect heart rate. The results emphasise that chewing gum can attenuate reductions in alertness, suggesting that chewing gum enhances worker performance.

  20. Detrimental effects of gum chewing on vigilance in children with attention deficit hyperactivity disorder.

    Science.gov (United States)

    Tucha, Lara; Simpson, William; Evans, Lynsay; Birrel, Laura; Sontag, Thomas A; Lange, Klaus W; Tucha, Oliver

    2010-12-01

    Impairments of attention are cardinal features of attention deficit hyperactivity disorder (ADHD) and can seriously affect the daily life of children with ADHD. Despite effective treatment strategies, there is a need of further treatment options that can be added to available and well established treatments. Further treatment options are needed since available treatments are often time consuming, expensive and limited regarding their external validity. Recent research demonstrated that gum chewing has beneficial effects on cognition including certain aspects of attention. Therefore, gum chewing may benefit children with ADHD in situations requiring particular cognitive efforts. In a crossover study, attentional functioning of 32 children with ADHD and 32 children without the condition was examined. All participants were assessed with chewing gum and without chewing gum. A computerized test was used for the assessment of vigilance and sustained attention. The findings of the present study suggest that gum chewing during task execution has detrimental effects on vigilance of both healthy children and children with ADHD. Sustained attention was not affected by gum chewing. Chewing gum, therefore, appears not to improve attentional performance in children with ADHD. Copyright © 2010 Elsevier Ltd. All rights reserved.