WorldWideScience

Sample records for behavior crystal morphology

  1. Morphology, Crystallization and Melting Behavior of Propylene-Ethylene Statistical Copolymers

    OpenAIRE

    Uan-Zo-li, Julie Tammy

    2005-01-01

    In this work the morphology, crystallization and melting behavior of novel Dow Chemical propylene-ethylene copolymers were investigated. The incorporation of ethylene units into a polypropylene chain resulted in the decrease in crystallization, melting and glass transition temperatures and overall crystallinity. Based on the shape of heat capacity curves and the dependence of the melting temperature offset on ethylene content, it was concluded that copolymers prepared using different ca...

  2. Influences of chemical aging on the surface morphology and crystallization behavior of basaltic glass fibers

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

    2008-01-01

    The impact of aging in high humidity and water on the surface morphology and crystallization behavior of basaltic glass fibers has been studied using scanning electron microscopy, transmission electron microscopy, calorimetry and X-ray diffraction. The results show that interaction between the...

  3. Morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate)/poly(ethylene-co-methacrylic acid) blends

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.-W. [Department of Styling and Cosmetology, Tainan University of Technology, 529 Chung Cheng Rd., Yung Kang City 710, Taiwan (China)], E-mail: jw.huang@msa.hinet.net; Wen, Y.-L. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Kang, C.-C. [R and D Center, Hi-End Polymer Film Co., Ltd. 15-1 Sin Jhong Rd., Sin Ying City 730, Taiwan (China); Yeh, M.-Y. [Department of Chemistry, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China); Sustainable Environment Research Centre, National Cheng Kung University, Taiwan (China); Wen, S.-B. [Department of Nursing, Meiho Institute of Technology, 23 Ping Kuang Rd., Neipu Hsiang, Pingtung 912, Taiwan (China); Department of Resources Engineering, National Cheng Kung University, No. 1, University Rd., Tainan City 701, Taiwan (China)

    2007-12-15

    The morphology, melting behavior, and non-isothermal crystallization of poly(butylene terephthalate) (PBT) and poly(ethylene-co-methacrylic acid) (PEMA) blends were studied with scanning electron microscopy, X-ray diffraction and differential scanning calorimetry (DSC). PEMA forms immiscible, yet compatible, blends with PBT. Subsequent DSC scans on melt-crystallized samples exhibited two melting endotherms (T{sub mI} and T{sub mII}). The presence of PEMA would facilitate the recrystallization during heating scan and retard PBT molecular chains to form a perfect crystal in cooling crystallization. The dispersion phases of molten PEMA acts as nucleating agents to enhance the crystallization rate of PBT. The solidified PBT could act as nucleating agents to enhance the crystallization of PEMA, but also retard the molecular mobility to reduce crystallization rate. The U* and K{sub g} of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation.

  4. Study on the crystal morphology and melting behavior of isothermally crystallized composites of short carbon fiber and poly(trimethylene terephthalate)

    Institute of Scientific and Technical Information of China (English)

    Mingtao RUN; Hongzan SONG; Yanping HAO

    2009-01-01

    The spherulites of the short carbon fibcr(SCF)/ poly (trimethylcne terephthalate) (PTT) composites forrned in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbandcd spherulites will form in the composites is not depondcnt on SCF content However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180℃ to 230℃, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Disconti-nuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the sphemlites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room tempera-ture at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the sphemlites.

  5. Effects of Degree of Enzymatic Interesterification on the Physical Properties of Margarine Fats: Solid Fat Content, Crystallization Behavior, Crystal Morphology, and Crystal Network

    DEFF Research Database (Denmark)

    Zhang, Hong; Smith, Paul; Adler-Nissen, Jens

    2004-01-01

    In this study enzymatic-interesterified margarine fats with different conversion degrees were produced in a packed-bed reactor. The effects of conversion degree on the formation of free fatty acids and diacyglycerols, solid fat content, crystallization behavior, microstructure, and crystal network...... was observed for both the blend and products. Isothermal crystallization kinetics was characterized by the Fisher- Turnbull model. The highest free energy was observed for the blend. A small deformation with oscillation tests shows a significant difference between the blend and interesterified products...

  6. Dynamic Mechanical Properties, Crystallization Behavior and Morphology of Nanoscale Tin Fluorophosphate Glass/Polyamide 66 Hybrid Materials.

    Science.gov (United States)

    Liu, Huiwen; Yang, Jing; Yu, Honglin; Zou, Xiaoxuan; Jing, Bo; Dai, Wenli

    2016-04-01

    The dynamic mechanical properties, crystallization behavior and morphology of nanoscale Tg tin fluorophosphate glass (TFP glass)/polyamide 66 (PA66) hybrid materials were investigated by XRD, DSC and SEM. The experimental results showed that the Tg of TFP/PA66 hybrid decreased and the third relaxation in the highly filled hybrid appeared due to the interaction between the TFP glass and amide groups of PA66. The storage modulus of the hybrid materials increased with increase in the content of TFP at low temperatures but had little effect at high temperatures. This result was attributed to the stiffness depression of the TFP glass when the temperature rose above its Tg and the similar elasticity of the two phases because of the interaction between the components. The degree of crystallinity and a, y crystal content of PA66 both decreased due to the interaction between the two phases. In addition, the phase defect, the size distribution and the compatibility of TFP in the PA66 matrix were discussed by SEM, the results showed that the TFP appeared aggregation partly, but had the favorable compatibility in the PA66 matrix. PMID:27451779

  7. CRYSTALLIZATION BEHAVIOR AND MORPHOLOGY OF ONE-STEP REACTION COMPATIBILIZED MICROFIBRILLAR REINFORCED ISOTACTIC POLYPROPYLENE/POLY(ETHYLENE TEREPHTHALATE) (iPP/PET) BLENDS

    Institute of Scientific and Technical Information of China (English)

    Ling Xu; Gan-ji Zhong; Xu Ji; Zhong-ming Li

    2011-01-01

    One-step reaction compatibilized microfibrillar reinforced iPP/PET blends (CMRB) were successfully prepared through a "slit extrusion-hot stretching-quenching" process.Crystallization behavior and morphology of CMRB were systematically investigated.Scanning electronic microscopy (SEM) observations showed blurry interface of eompatibilized common blend (CCB).The crystallization behavior of neat iPP,CCB,microfibrillar reinforced iPP/PET blend (MRB) and CMRB was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM).The increase of crystallization temperature and crystallization rate during nonisothermal crystallization process indicated both PET particles and microfibrils could serve as nucleating agents and PET microfibrils exhibited higher heterogeneous nucleation ability,which were also vividly revealed by results of POM.Compared with MRB sample,CMRB sample has lower crystallization temperature due to existence of PET microfibrils with smaller aspect ratio and wider distribution.In addition,since in situ compatibilizer tends to stay in the interphase,it could also hinder the diffusion ofiPP molecules to the surface of PET phase,leading to decrease of crystallization rate.Two-dimensional wide-angle X-ray diffraction (2D-WAXD) was preformed to characterize the crystalline structure of the samples by injection molding,and it was found that well-developed PET microfibrils contained in MRB sample promoted formation ofβ-phase of fPP.

  8. Graphene single crystals: size and morphology engineering.

    Science.gov (United States)

    Geng, Dechao; Wang, Huaping; Yu, Gui

    2015-05-13

    Recently developed chemical vapor deposition (CVD) is considered as an effective way to large-area and high-quality graphene preparation due to its ultra-low cost, high controllability, and high scalability. However, CVD-grown graphene film is polycrystalline, and composed of numerous grains separated by grain boundaries, which are detrimental to graphene-based electronics. Intensive investigations have been inspired on the controlled growth of graphene single crystals with the absence of intrinsic defects. As the two most concerned parameters, the size and morphology serve critical roles in affecting properties and understanding the growth mechanism of graphene crystals. Therefore, a precise tuning of the size and morphology will be of great significance in scale-up graphene production and wide applications. Here, recent advances in the synthesis of graphene single crystals on both metals and dielectric substrates by the CVD method are discussed. The review mainly covers the size and morphology engineering of graphene single crystals. Furthermore, recent progress in the growth mechanism and device applications of graphene single crystals are presented. Finally, the opportunities and challenges are discussed. PMID:25809643

  9. Optimised crystal morphologies for active pharmaceutical ingredients and related studies

    OpenAIRE

    Horgan, Danielle E.

    2015-01-01

    The majority of active pharmaceutical ingredients (APIs) are crystalline solids in their pure forms. Crystalline solids have definable morphologies, i.e. shape and size. Crystal morphology is determined by both the internal structure of the crystals and external factors during growth from solution. The morphology of a crystal batch can affect key processes during manufacturing. Companies generally accept whatever morphology the manufacturing process provides and deal with any subsequent probl...

  10. Unifying the crystallization behavior of hexagonal and square crystals with the phase-field-crystal model

    Science.gov (United States)

    Tao, Yang; Zheng, Chen; Jing, Zhang; Yongxin, Wang; Yanli, Lu

    2016-03-01

    By employing the phase-field-crystal models, the atomic crystallization process of hexagonal and square crystals is investigated with the emphasis on the growth mechanism and morphological change. A unified regime describing the crystallization behavior of both crystals is obtained with the thermodynamic driving force varying. By increasing the driving force, both crystals (in the steady-state) transform from a faceted polygon to an apex-bulged polygon, and then into a symmetric dendrite. For the faceted polygon, the interface advances by a layer-by-layer (LL) mode while for the apex-bulged polygonal and the dendritic crystals, it first adopts the LL mode and then transits into the multi-layer (ML) mode in the later stage. In particular, a shift of the nucleation sites from the face center to the area around the crystal tips is detected in the early growth stage of both crystals and is rationalized in terms of the relation between the crystal size and the driving force distribution. Finally, a parameter characterizing the complex shape change of square crystal is introduced. Project supported by the National Natural Science Foundation of China (Grant Nos. 54175378, 51474176, and 51274167), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2014JM7261), and the Doctoral Foundation Program of Ministry of China (Grant No. 20136102120021).

  11. Molecular morphology and crystallization in the quantum limit

    DEFF Research Database (Denmark)

    Bohr, Jakob

    2002-01-01

    The effects of phonons on crystallization and crystal morphology are investigated. It is shown that the commensuration of the lattice vibrations with the lattice will favor certain crystal morphologies. Vibrational effects can also be important for the molecular structure of chain molecules...

  12. Incorporation of tin affects crystallization, morphology, and crystal composition of Sn-Beta

    DEFF Research Database (Denmark)

    Tolborg, Søren; Katerinopoulou, A.; Falcone, D. D.;

    2014-01-01

    only drastically a ff ects the time required for crystallization, but also that the presence of tin changes the morphology of the formed Sn-Beta crystals. For low amounts of tin (Si/Sn ¼ 400) crystallization occurs within four days and the Sn-Beta crystals are capped bipyramidal in shape, whereas for...

  13. Studies on confined crystallization behavior of polycaprolactone thin films

    Institute of Scientific and Technical Information of China (English)

    QIAO Congde; JIANG Shichun; JI Xiangling; AN Lijia; JIANG Bingzheng

    2007-01-01

    The confined crystallization behavior ofpolycap-rolactone (PCL) in thin and ultrathin films was studied by AFM (atomic force microscopy). It was found that the crys-talline morphology of PCL depended on the film's thickness.When the thickness is d>2Rg (radius of gyration), the polymer can crystallize into spherulites; when Rg < d< 2 Rg,a dense-branch morphology and dendrites could be found;when dcrystallization temperature and the substrate and the molecular weigbt on the crystalline mor-phology were discussed. It was shown that the crystallization of PCL in thin films is a diffusion-controlled process, and it can be explained by diffusion-limited aggregation.

  14. Growth morphology and structural characteristic of C70single crystals

    Institute of Scientific and Technical Information of China (English)

    周维亚; 解思深; 吴源; 常保和; 王刚; 钱露茜

    1999-01-01

    Large size C70 single crystals with the dimension of more than 5 mm are grown from the vapor phase by controlling nucleation. X-ray diffraction and electron diffraction confirm that in the C70 single crystal a phase of the hexagonal close-packed (hcp) structure coexists with a minor face-center-cubic (fcc) phase at room temperature. The morphologies and their formation mechanism of the C70 single crystals are investigated by means of scanning electron microscopy and optical microscopy. The influence of growth conditions on the morphologies of C70 single crystals is discussed.

  15. CRYSTALLIZATION BEHAVIOR OF POLYLACTIDE ON HIGHLY ORIENTED POLYETHYLENE THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    Yu-kuan An; Shi-dong Jiang; Shou-ke Yan; Jing-ru Sun; Xue-si Chen

    2011-01-01

    The crystalline structure and morphology of the PLA crystallized isothermally from the glassy state on highly oriented PE substrates at 130℃ were investigated by means of optical microscopy, AFM and X-ray diffraction. The results indicate that the PE substrate influences the crystallization behavior of PLA remarkably, which leads to the growth of PLA crystals on PE substrate always in edge-on form rather than the twisted lamellar crystals from edge-on to flat-on when crystallizing the PLA on glass surface under the same condition. The edge-on PLA lamellae on the PE substrate are preferentially arranged with their long axes in the chain direction of the PE substrate crystals. It is further demonstrated that except for the different crystal orientation, the PE does not influence the crystalline modification and crystallinity of the PLA.

  16. Protein induced morphological transitions in KCl crystal growth

    CERN Document Server

    Szabó, B; Szabo, Balint; Vicsek, Tamas

    2003-01-01

    We investigated the formation of KCl crystals on glass surface by phase contrast, fluorescent, and atomic force microscopy on the micrometer scale, and observed interesting morphological transitions as a function of the experimental conditions. The presence of proteins in the solution from which the salt crystals grow during the drying up leads to complex microscopic patterns of crystals some of which are analogous to those commonly observed on the macroscopic scale. We tested the effect of tubulin, FITC-labeled albumin and IgG on the morphology of crystals grown either slowly or fast. A rich variety of protein specific and concentration dependent morphologies was found and described by a morphological diagram. We give a phenomenological interpretation, which can explain the growth of complex patterns. Fluorescent images prove that a protein layer covers the surface of the KCl structures. We propose that this layer reduces the anisotropy of the effective surface tension during growth. The tip splitting fracta...

  17. Dendrite crystal morphology evolution mechanism of β-BaB2O4 crystal

    Institute of Scientific and Technical Information of China (English)

    HE ChongJun; ZHONG WeiZhuo; LIU YouWen

    2009-01-01

    Existence of [B3-O6]3- hexagonal ring growth unit in melt solution of β-BaB2O4 crystal was proved by the results of high temperature Raman measurements. A morphology evolution process of β-BaB2O4 crys-tal was observed by a high temperature in-situ observation device. The crystal morphology varied with the supersaturation of growth melt solution. The mechanism of β-BaB2O4 crystal morphology evolution was analyzed through the growth unit model.

  18. Dendrite crystal morphology evolution mechanism of β-BaB2O4 crystal

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Existence of [B3-O6]3- hexagonal ring growth unit in melt solution of β-BaB2O4 crystal was proved by the results of high temperature Raman measurements.A morphology evolution process of β-BaB2O4 crys-tal was observed by a high temperature in-situ observation device.The crystal morphology varied with the supersaturation of growth melt solution.The mechanism of β-BaB2O4 crystal morphology evolution was analyzed through the growth unit model.

  19. Morphological and optical properties of doped potassium hydrogen phthalate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Enculescu, M., E-mail: mdatcu@infim.r [National Institute of Materials Physics, Multifunctional Materials and Structures Laboratory, PO Box MG-7, 077125 Magurele-Bucharest (Romania)

    2010-09-01

    Potassium hydrogen phthalate (KAP) crystals doped with rhodamine 6G (Rh 6G) and polyvinylpyrrolidone (PVP) were grown by solution evaporation technique. Nucleation occurred without the use of seeds and optically transparent crystals were obtained. The grown crystals were characterized by XRD measurements performed on crystals and their powders, optical transmission and photoluminescence measurements. The influence of the dopants on the structural, morphological and optical properties of the KAP crystals was analysed. Dopants do not change the structure of the single crystals while the addition of PVP changes the morphology of crystals from pseudo-hexagonal to rhomb. Three new XRD reflections are observed in all single-crystal and powder XRD spectra and are probably (0 3 0), (0 4 0) and (0 5 0) lines. The UV cut-off and transparency of the crystals are not changed by doping. Dye-doped KAP crystals exhibit a strong emission band centred at 550 nm excited with 480 nm wavelength. For the dye-doped crystals the up-conversion was investigated and its second harmonic origins are proved using photoluminescence measurements.

  20. Influential Factors on Morphology of Hydroxyapatite Crystals

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Needle-like hydroxyapatite crystals were synthesized by homogeneous precipitation method with water-soluble calcium salts and phosphates.The work focuses on the analysis of influencing factors on length and lengh/diameter ratio of hydroxyapatite crystals,which are main characteristics of reinforcement materials.The effects caused by system temperature,concentration of nutrient,and additives are discussed,and the optimum reacting condition is given.

  1. NONISOTHERMAL CRYSTALLIZATION AND MORPHOLOGY OF POLY(BUTYLENE SUCCINATE)/LAYERED DOUBLE HYDROXIDE NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Mei-qiu Zhan; Guang-yi Chen; Zhi-yong Wei; Yu-mei Shi; Wan-xi Zhang

    2013-01-01

    Biodegradable poly(butylene succinate) (PBS) and layered double hydroxide (LDH) nanocomposites were prepared via melt blending in a twin-screw extruder.The morphology and dispersion of LDH nanoparticles within PBS matrix were characterized by transmission electron microscopy (TEM),which showed that LDH nanoparticles were found to be well distributed at the nanometer level.The nonisothermal crystallization behavior of nanocomposites was extensively studied using differential scanning calorimetry (DSC) technique at various cooling rates.The crystallization rate of PBS was accelerated by the addition of LDH due to its heterogeneous nucleation effect; however,the crystallization mechanism and crystal structure of PBS remained almost unchanged.In kinetics analysis of nonisothermal crystallization,the Ozawa approach failed to describe the crystallization behavior of PBS/LDH nanocomposites,whereas both the modified Avrami model and the Mo method well represented the crystallization behavior of nanocomposites.The effective activation energy was estimated as a function of the relative degree of crystallinity using the isoconversional analysis.The subsequent melting behavior of PBS and PBS/LDH nanocomposites was observed to be dependent on the cooling rate.The POM showed that the small and less perfect crystals were formed in nanocomposites.

  2. Crystal morphology of sunflower wax in soybean oil organogel

    Science.gov (United States)

    While sunflower wax has been recognized as an excellent organogelator for edible oil, the detailed morphology of sunflower wax crystals formed in an edible oil organogel has not been fully understood. In this study, polarized light microscopy, phase contrast microscopy, scanning electron microscopy ...

  3. CRYSTALLIZATION AND MORPHOLOGY OF STAR-SHAPED POLYETHYLENOXYDE-b-POLYCAPROLACTONE UNDER HIGH PRESSURE CARBON DIOXIDE

    Institute of Scientific and Technical Information of China (English)

    Ya Li; Jian Zhou; Jun Li; Qu-ting Gou; Qun Gu; Zong-bao Wang

    2012-01-01

    Atomic force microscopy (AFM),wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry are used to analyze the crystallization morphology and melting behavior of 4-arm PEO-b-PCL under high-pressure CO2.It is demonstrated that CO2 has certain effect on the melting and crystallization behavior of the samples.After crystallization under CO2 at 4 MPa,spherulites with concentric ring-banded structure are formed which are composed of crystals with periodic thickness variation,and the band distance decreases with increasing treatment pressure.Due to the plasticization effect of CO2,depression of the melting temperature is observed with sorption of CO2 in polymers.

  4. Crystal Growth, Structure and Morphology of Rifapentine Methanol Solvate

    Institute of Scientific and Technical Information of China (English)

    周堃; 李军; 罗建洪; 金央

    2012-01-01

    Rifapentine, an important antibiotic, was crystallized from methanol solvent in the form of its methanol solvate. The crystal structure of rifapentine methanol solvate belongs to monoclinic, space group P21, with the unit cell parameters of a = 1.2278(3) nm, b = 1.9768(4) rim, c = 1.2473(3) nm, Z= 2, and β = 112.35(3). The parallelepiped.morphology was also predicted by Materials Studio simulation program.. The influence of intermolecular in-teraction was taken into account in the attachment energy model. The crystal shape fits the calculated morphology well, which was performed on the potential energy minimized model using a generic DREIDING 2.21 force fieldand developed minimization protocol with derived'partial charges.

  5. Growth morphology of zinc tris(thiourea) sulphate crystals

    Indian Academy of Sciences (India)

    Sunil Verma; M K Singh; V K Wadhawan; C H Suresh

    2000-06-01

    The growth morphology of crystals of zinc tris(thiourea) sulphate (ZTS) is investigated experimentally, and computed using the Hartman–Perdok approach. Attachment energies of the observed habit faces are calculated for determining their relative morphological importance. A computer code is developed for carrying out these calculations. A special procedure is adopted for computing the cohesive energy of a slice of the structure parallel to any rational crystallographic plane. For estimating the cohesive energies, formal charges on the experimentally determined atomic positions in the molecules of ZTS are calculated by ab initio molecular-orbital computations, with wave functions obtained by the Hartree–Fock procedure. Fairly good agreement with the observed crystal morphology is obtained for a model of growth mechanism in which ZTS is assumed to exist in solution as zinc tris(thiourea) ions and sulphate ions.

  6. The evolution and morphological stability of a spherical crystal

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The growth model of a spherical crystal in the undercooled melt including the sur- face energy, interfacial kinetics and convective flow is established. The effect of the convective flow induced by a small far field flow on the evolution and morphologi- cal stability of the interface of the spherical crystal is studied. The interface shape of the spherical crystal, which is affected by the far field flow, and the dispersion relation of the growth rate of amplitude of the perturbed interface are derived. It is shown that the convection induced by the far field flow makes the interface of the growing spherical crystal further grow in the upstream direction of the far field flow and inhibit growth in the downstream direction; the interface of the decaying spherical crystal further decays in the upstream direction and inhibits decay in the downstream direction. The theoretical result suggests that both the growth of the sphere in the upstream direction and the decay of the sphere in the downstream direction make the spherical crystal tend to evolve into an oval; the morphological stability of the interface depends on a certain radius Rc such that the spherical crystal is unstable when its radius is greater than Rc and stable when its radius is less than Rc. The surface energy and interfacial kinetics have strong stabilizing effects on the growth of the spherical crystal. In the meantime interfacial kinetics is a stable factor of the interface when the interface of the sphere is growing; it is an unstable factor of the interface when the interface is decaying.

  7. SOLUTION CRYSTALLIZATION OF METALLOCENE SHORT CHAIN BRANCHED POLYETHYLENE: MORPHOLOGY AND MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Qiang Fu; Rong-ni Du; Fang-Chyou Chiu

    2000-01-01

    Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nice single crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirty due to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncated lozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperature than in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonal packing in a crystallization temperature range. The lateral habits of single crystal are discussed based on roughening theories.

  8. Sequential crystallization and morphology of triple crystalline biodegradable PEO-b-PCL-b-PLLA triblock terpolymers

    KAUST Repository

    Palacios, Jordana

    2016-01-05

    The sequential crystallization of poly(ethylene oxide)-b-poly(e-caprolactone)-b-poly(L-lactide) (PEO-b-PCL-b-PLLA) triblock terpolymers, in which the three blocks are able to crystallize separately and sequentially from the melt, is presented. Two terpolymers with identical PEO and PCL block lengths and two different PLLA block lengths were prepared, thus the effect of increasing PLLA content on the crystallization behavior and morphology was evaluated. Wide angle X-Ray scattering (WAXS) experiments performed on cooling from the melt confirmed the triple crystalline nature of these terpolymers and revealed that they crystallize in sequence: the PLLA block crystallizes first, then the PCL block, and finally the PEO block. Differential scanning calorimetry (DSC) analysis further demonstrated that the three blocks can crystallize from the melt when a low cooling rate is employed. The crystallization process takes place from a homogenous melt as indicated by small angle X-Ray scattering (SAXS) experiments. The crystallization and melting enthalpies and temperatures of both PEO and PCL blocks decrease as PLLA content in the terpolymer increases. Polarized light optical microscopy (PLOM) demonstrated that the PLLA block templates the morphology of the terpolymer, as it forms spherulites upon cooling from the melt. The subsequent crystallization of PCL and PEO blocks occurs inside the interlamellar regions of the previously formed PLLA block spherulites. In this way, unique triple crystalline mixed spherulitic superstructures have been observed for the first time. As the PLLA content in the terpolymer is reduced the superstructural morphology changes from spherulites to a more axialitic-like structure.

  9. Large deformation behavior of fat crystal networks

    NARCIS (Netherlands)

    Kloek, W.; Vliet, van T.; Walstra, P.

    2005-01-01

    Compression and wire-cutting experiments on dispersions of fully hydrogenated palm oil in sunflower oil with varying fraction solid fat were carried out to establish which parameters are important for the large deformation behavior of fat crystal networks. Compression experiments showed that the app

  10. Morphology, crystal structure and hydration of calcined and modified anhydrite

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing Niu; Ji-chun Chen

    2014-01-01

    The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100°C causes anhydrite to disintegrate into smaller crystals, accompanied by a slight in-crease in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 min, respectively. The com-pressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material.

  11. Polymer's anchoring behavior in liquid crystal cells

    Science.gov (United States)

    Cui, Yue

    The current dissertation mainly discusses about the polymers anchoring behavior in liquid crystal cells in two aspects: surface interaction and bulk interaction. The goal of the research is to understand the fundamental physics of anchoring strength and apply the knowledge to liquid crystal display devices. Researchers proposed two main contributors to the surface anchoring strength: the micro grooves generated by external force and the polymer chain's alignment. Both of them has experimental proofs. In the current study, explorations were made to understand the mechanisms of surface anchoring strength and easy axis of surface liquid crystal provided by rubbed polymer alignment layer. The work includes not only the variation of the alignment layer itself such as thickness(Chapter 3) and polymer side chain (Chapter 5), but also the variation of external conditions such as temperature (Chapter 4) and rubbing condition (Chapter 6). To determine the polar and azimuthal anchoring strengths, Rapini-Papoular's expression was applied. However, it was discovered that higher order terms may be required in order to fit the experimental result or theoretically predict unique anchoring behaviors (Chapter 2, Chapter 6). SEM and AFM technologies were introduced to gather the actual structures of polymer alignment layer and extrapolate the alignment of liquid crystal in a micro scale. The result shows that the anchoring strength can be adjusted by the layer thickness, side chain structure, while the easy axis direction can be adjusted by a second rubbing direction. In addition, different anchoring conditions combined with liquid crystal's elastic energy can generate quite different forms of liquid crystals (Chapter 7). In the study of bulk alignment, the main contrition from the current dissertation is applying the understanding of anchoring behavior to optimizing actual switchable devices. Conventional PDLC performance can be tuned with the knowledge of the polymer and the liquid

  12. The influence of a solvent on the crystal morphology of RDX

    NARCIS (Netherlands)

    Horst, J.H. ter; Geertman, R.M.; Heijden, A.E.D.M. van der; Rosmalen, G.M. van

    1999-01-01

    A solvent can have a large influence on the crystal morphology. A molecular modeling technique based on the adsorption of solvent molecules on a crystal surface has been used to predict the influence of a solvent on the morphology of RDX. The predicted morphology has been compared with the experimen

  13. Morphological control and polarization switching in polymer dispersed liquid crystal materials and devices

    Indian Academy of Sciences (India)

    K K Raina; Pankaj Kumar; Praveen Malik

    2006-11-01

    Liquid crystals dispersed in polymer systems constitute novel class of optical materials. The precise control of the liquid crystal droplet morphology in the polymer matrix is essentially required to meet the prerequisites of display device. Experiments have been carried out to investigate and identify the material properties and processing conditions required for the precise control of the droplet morphology of the dispersed liquid crystal systems. Polarization switching has been studied. Aligned liquid crystal dispersed systems showed higher polarization over unaligned ones.

  14. Influence of impurities on the surface morphology of the TIBr crystal semiconductor

    International Nuclear Information System (INIS)

    The impurity effect in the surface morphology quality of TlBr crystals was evaluated, aiming a future application of these crystals as room temperature radiation semiconductor detectors. The crystals were purified and grown by the Repeated Bridgman technique. Systematic measurements were carried out for determining the stoichiometry, structure orientation, surface morphology and impurity of the crystal. A significant difference in the crystals impurity concentration was observed for almost all impurities, compared to those found in the raw material. The crystals wafer grown twice showed a surface roughness and grains which may be due to the presence of impurities on the surface, while those obtained with crystals grown three times presented a more uniform surface: even though, a smaller roughness was still observed. It was demonstrated that the impurities affect strongly the surface morphology quality of crystals. (author)

  15. Studies on the effect of L-glutamine on morphology, structure, optical, mechanical and electrical properties of TGS crystal

    Science.gov (United States)

    Bharthasarathi, T.; Thakur, O. P.; Murugakoothan, P.

    2010-09-01

    Single crystals of L-glutamine doped triglycine sulfate (LGTGS) were grown from aqueous solution by low-temperature solution growth technique using slow cooling method. The LGTGS crystals exhibit prominent morphological changes in the (1 0 1) and (0 1 0) planes. Lattice parameter values were determined by single-crystal XRD analysis. The powder X-ray diffraction confirms the crystalline nature of LGTGS. The presence of dopants in the crystal lattice was qualitatively confirmed by FTIR analysis. The UV-vis-NIR spectrum was recorded to study the optical transparency of the grown crystals. Microhardness studies were carried out using Leitz Weitzler hardness tester at room temperature. The dielectric studies were carried out to identify the phase transition temperature and the dielectric behavior. The P- E hysteresis loops were recorded at 50 Hz to find the values of spontaneous polarization ( Ps) and coercive field ( Ec).

  16. Spectroscopic and morphological investigation of conjugated photopolymerisable quinquethiophene liquid crystals

    KAUST Repository

    McGlashon, Andrew J.

    2012-09-01

    3′-methyl-(5,5′′-bis[3-ethyl-3-(6-phenyl-hexyloxymethyl) -oxetane])-2,2′:5′,2′′-terthiophene (5T(Me)Ox) is a solution processable small molecule semiconductor displaying smectic-C and nematic liquid crystal phases. The pendant oxetane group can be polymerized in situ in the presence of a suitable photoacid at concentrations ≥1% by weight. Spin-coated films of pure 5T(Me)Ox and 5T(Me)Ox doped with the soluble photoacid were characterized by absorption and photoluminescent spectroscopy. Thick pristine films showed absorption and emission from a crystalline phase. Thin monolayer (<5 nm) films, as well as thicker photoacid doped films, instead showed absorption from an H-aggregate phase and emission from an excimer. Optical microscopy showed a significant change in film structure upon addition of the photoacid; large and well-orientated crystals being replaced by much smaller domains which appear to vary in thickness. Grazing Incidence Wide Angle X-Ray Scattering (GIWAXS) was used to characterize the packing and orientation of molecules in the crystalline and doped samples. The results are consistent with the photoacid doped samples forming layers of H-aggregate phase monolayer sheets parallel to the substrate where the photoacid inhibits the transition into the three-dimensionally ordered crystalline phase. Field-effect transistors and light emitting diodes were constructed incorporating 5T(Me)Ox as the active layer. Pure 5T(Me)Ox field-effect transistors showed good, p-type device characteristics, but the morphological changes upon doping result in a loss of transistor action. In the diodes, curing through melting and exposure to UV light followed by photoacid removal resulted in an increase in current density but a decrease in light emission. These results indicate that the presence of the photoacid (≥1% by weight) can have a dramatic effect on the structure, morphology and device performance of ordered, photopatternable materials for organic

  17. Evolution of Morphology and Structure During Crystallization and Melting in Syndiotactic Polypropylene

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Structure and morphology development during isothermal crystallization andsubsequent melting of syndiotactic polypropylene (Spp) was studied by time-resolvedsimultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD)methods with synchrotron radiation and differential scanning calorimetry(DSC). The timeand temperature dependent parameters such as long period, L, crystal lamellar thickness, lc,amorphous layer thickness, la, scattering invariant, 6, crystallinity, Xc, lateral crystalsizes, L200 and L020, and unit cell parameters a and b were extracted from SAXS and WAXDprofiles. Decreasing long period and crystal thickness indicate that thinner secondary crystallamellae are formed. The decreases in unit cell parameters a and b during isothermalcrystallization process suggest that crystal perfection takes place. The changes in themorphological parameters (the invariant, Q, crystallinity, Xc, long period, L, and thecrystal thickness, lc) during subsequent melting were found to follow a two-stage meltingprocess, corresponding to the dual endotherm behavior in the DSC scan. We conclude that the dual melting peaks are due to the melting of secondary and primary lamellae(first peak)and the subsequent recrystallization-melting process (second peak). Additional minorendothermic peak located at the lowest temperature was also detected and might be related tomelting of secondary, thinner and defective lamellae. WAXD showed that during melting,thermal expansion was greater along the b axis than that along the a axis.

  18. STEREOREGULAR POLY(CYCLOHEXENE CARBONATE)S: UNIQUE CRYSTALLIZATION BEHAVIOR

    Institute of Scientific and Technical Information of China (English)

    Guang-peng Wu; Shi-dong Jiang; Xiao-bing Lu; Wei-min Ren; Shou-ke Yan

    2012-01-01

    An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported.Isotacticity of poly(cyclohexene carbonate) (PCHC) has the critical influence on the crystallinity,and only copolymers with a isotacticity of more than 90% are crystallizable.The stereoregular PCHC is a typical semi-crystalline thermoplastic,and possesses a high melting point (Tm) of 215-230℃ and a decomposition temperature of ca.310℃.The spherulitic morphology of (R)-PCHC grows in a clockwise spiral from a center,and that of (S)-PCHC is a counterclockwise spiral,while the stereocomplex of (S)-PCHC/(R)-PCHC (1/1 mass ratio) presents lath-like dendritic crystal.The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior.Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials,and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.

  19. An Experimental Verification of morphology of ibuprofen crystals from CAMD designed solvent

    DEFF Research Database (Denmark)

    Karunanithi, Arunprakash T.; Acquah, Charles; Achenie, Luke E.K.;

    2007-01-01

    of crystals formed from solvents, necessitates additional experimental verification steps. In this work we report the experimental verification of crystal morphology for the case study, solvent design for ibuprofen crystallization, presented in Karunanithi et al. [2006. A computer-aided molecular design...

  20. Influence of magnetic field on the morphology of the andrographolide crystal from supercritical carbon dioxide extraction crystallization

    Science.gov (United States)

    Chen, Kexun; Zhang, Xingyuan; Pan, Jian; Zhang, Wencheng; Yong, Ji; Yin, Wenhong

    2003-10-01

    In this paper, a supercritical fluid extraction-crystallization of andrographolide, a kind of Chinese traditional medicine, was investigated. We have studied the extraction-crystallization process with or without magnet in the extractor, respectively. It was found that the presence of magnetic field is an important factor influencing the quality of the products. SEM images showed that the crystal was slice-like in shape, and many slices reunited together in the absence of magnet. Further research showed that pressure had a certain effect on the morphology of the crystal.

  1. Effect of milling on morphology of molten salt synthesized Sr3Ti2O7 crystals

    Directory of Open Access Journals (Sweden)

    Kijamnajsuk, S.

    2007-07-01

    Full Text Available Effect of milling liquid (acetone and ethanol, and milling times on morphology of Sr3Ti2O7 (ST7 crystals grow in molten potassium chloride salt at 1250oC for 4 h was investigated. Two kinds of crystals with different morphologies were found: ST7 crystals having a tabular shape of less than 20 μm diameter and small secondary-phase crystals having high symmetry. Milling starting materials in ethanol yielded ST7 crystals that were up to 3 times thinner than those milled with acetone, increasing the (00l Lotgering factor almost twice that when prepared with acetone. Large crystals become a bit smaller and the number of small crystals increased when the milling time increased.

  2. Growth of NBT-BT single crystals by flux method and their structural, morphological and electrical characterizations

    Science.gov (United States)

    Kanuru, Sreenadha Rao; Baskar, K.; Dhanasekaran, R.; Kumar, Binay

    2016-05-01

    In this paper, one of the important, eco-friendly polycrystalline material, (1-x)(Na0.5Bi0.5)TiO3 (NBT) - xBaTiO3 (BT) of different compositions (x=0.07, 0.06 and 0.05 wt%) around the morphotropic phase boundary (MPB) were synthesized by solid state reaction technique. And the single crystals with 13×7×7 mm3, 12×12×7 mm3 and 10×7×4 mm3 dimensions were grown by self flux method. The morphology, crystal structure and unit-cell parameters have been studied and the monoclinic phase has been identified for 0.07 wt% of BT. Higher BT concentration changes the crystal habit and the mechanism has been studied clearly. Raman spectroscopy at room-temperature confirms the presence of functional groups. The quality of the as grown single crystals was examined by high resolution x-ray diffraction analysis. The dielectric properties of the as grown crystals were investigated in the frequency range of 20 Hz-2 MHz from room temperature to 450 °C. The broad dielectric peak and frequency dispersion demonstrates the relaxor behavior of grown crystals. The dielectric constant (εr), transition temperature (Tm), and depolarization temperature (Td) of the grown crystals are found to be comparatively good. The diffusive factor (γ) from Curie-Weiss law confirms the as grown NBT-BT single crystals are relaxor in nature.

  3. MULTIPLE MELTING AND CRYSTALLIZATION BEHAVIOR OF NYLON 1212

    Institute of Scientific and Technical Information of China (English)

    Jian-bin Song; Qing-yong Chen; Min-qiao Ren; Xiao-hong Sun; Hui-liang Zhang; Hong-fang Zhang; Shu-yun Wang; Zhi-shen Mo

    2006-01-01

    The wide-angle X-ray diffraction (WAXD) patterns of isothermally crystallized Nylon 1212 show that γ-form crystals form below 90℃ and the α-form crystals can exist above 140℃. In the temperature range of 90-140℃, the α-form and γ-form crystals coexist. Variable-temperature WAXD exhibits that the nylon 1212 γ-form does not show crystal transition on heating, while α-form isothermally crystallized at 160℃ exhibits Brill transition at a little higher than 180℃ on heating. The multiple melting behaviors of Nylon 1212 isothermally crystallized from melt come from a complex mechanism of different crystal structures, dual lamellar population and melting-recrystallization. In polarized optical microscope (POM) observations, Nylon 1212 isothermally crystallized at 175℃ shows the ringed banded spherulites. However, at temperatures below 160℃ the ringed banded image disappears, and cross-extinct spherulites are formed.

  4. Crystallization Behavior of Copper Smelter Slag During Molten Oxidation

    Science.gov (United States)

    Fan, Yong; Shibata, Etsuro; Iizuka, Atsushi; Nakamura, Takashi

    2015-10-01

    Copper slag is composed of iron silicate obtained by smelting copper concentrate and silica flux. One of the most important criteria for the utilization of this secondary resource is the recovery of iron from the slag matrix to decrease the volume of dumped slag. The molten oxidation process with crushing magnetic separation appears to be a more sustainable approach and is based on directly blowing oxidizing gas onto molten slag after the copper smelting process. In the current study, using an infrared furnace, the crystallization behavior of the slag during molten oxidation was studied to better understand the trade-off between magnetite and hematite precipitations, as assessed by X-ray diffraction (using an internal standard). Furthermore, the crystal morphology was examined using a laser microscope and Raman imaging system to understand the iron oxide transformation, and the distribution of impurities such as Cu, Zn, As, Cr, and Pb were complemented with scanning electron microscopy and energy dispersive spectroscopy. In addition, the reaction mechanism was investigated with a focus on the oxidation processes.

  5. Crystallization Behavior of Copolymer Poly (ethylene terephthalate/isophthalate) (IPET)

    Institute of Scientific and Technical Information of China (English)

    顾书英; 肖茹; 顾利霞

    2001-01-01

    The non-isothermal crystallization kinetics, isothermal crystallization and the morphology of crystals of the copolymer poly (ethylene terephthalate/ isophthalate )(IPET) were studied by DSC and polarized-light microscopy in this paper. DSC results indicate that the glass transition temperature Tg of IPET is slightly lower than that of poly(ethylene terephthalate) (PET), but the melting temperature Tm and the crystallization temperature Tc of PET and IPET have much difference.The difference of Tc between PET and IPET2 is about 7℃, and the difference of Tm between PET and IPET2 is about 16℃. From the kinetics analysis of the crystallization, the crystallization mechanism of all samples is of three-dimension spherulitic growth from instantaneous nuclei and the incorporation of isophthalate (IPA) decreases the crystallization rate of IPET greatly. The isothermal results indicate that the morphologies of PET and IPET crystals are all spherulite, which is in conformity to the results of nonisothermal dynamic crystallization. At the same time,the spherulite of IPET grows slower and has longer incubation time than the spherulite of PET under the same crystallization condition.

  6. Multiwall carbon nanotubes doped ferroelectric liquid crystal composites: A study of modified electrical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Neeraj, E-mail: neerajvenus@gmail.com [Department of Physics, Sant Hira Dass Kanya Maha Vidyalaya, Kala Sanghian, Kapurthala 144623, Punjab (India); Raina, K.K., E-mail: kkraina@gmail.com [Materials Research Laboratory, School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India)

    2014-02-01

    We systematically investigated the role of carbon nanotubes and their nature of interaction with the high polarization ferroelectric liquid crystal molecules that causes a change in the dynamic behavior of the liquid crystals. The carbon nanotubes were functionalized with carboxyl group (–COOH) before dispersion in order to enhance their stability in the liquid crystal medium. For the systematic investigation of a non linear behavior of dispersed composite systems, results for various physical properties were determined by thermal, morphological and dielectric studies in the planer aligned 5 μm thickness cells. An effort has also gone into detail to investigate these properties with varying concentration (0.02 wt%, 0.05 wt% and 0.1 wt%) of multiwall carbon nanotubes. The various carbon nanotubes doped ferroelectric liquid crystal thin film composites have shown enhanced dielectric strength and dielectric permittivity values as compared to the undoped sample.

  7. Tuning the crystal morphology and size of zeolitic imidazolate framework-8 in aqueous solution by surfactants

    KAUST Repository

    Pan, Yichang

    2011-01-01

    Herein we report a facile synthesis method using surfactant cetyltrimethylammonium bromide (CTAB) as a capping agent for controlling the crystal size and morphology of zeolitic imidazolate framework-8 (ZIF-8) crystals in aqueous systems. The particle sizes can be precisely adjusted from ca. 100 nm to 4 μm, and the morphology can be changed from truncated cubic to rhombic dodecahedron. This journal is © The Royal Society of Chemistry.

  8. A Study of the Crystallization, Melting, and Foaming Behaviors of Polylactic Acid in Compressed CO2

    Directory of Open Access Journals (Sweden)

    Chul B. Park

    2009-12-01

    Full Text Available The crystallization and melting behaviors of linear polylactic acid (PLA treated by compressed CO2 was investigated. The isothermal crystallization test indicated that while PLA exhibited very low crystallization kinetics under atmospheric pressure, CO2 exposure significantly increased PLA’s crystallization rate; a high crystallinity of 16.5% was achieved after CO2 treatment for only 1 min at 100 °C and 6.89 MPa. One melting peak could be found in the DSC curve, and this exhibited a slight dependency on treatment times, temperatures, and pressures. PLA samples tended to foam during the gas release process, and a foaming window as a function of time and temperature was established. Based on the foaming window, crystallinity, and cell morphology, it was found that foaming clearly reduced the needed time for PLA’s crystallization equilibrium.

  9. The role of impurities on the morphology of NaCl crystals : an atomic scale view

    NARCIS (Netherlands)

    Radenovic, N.

    2005-01-01

    It is well known that crystal growth and morphology are largely influenced by the presence of impurities in the growth solution. However, little is known about the actual process of impurity interaction with the growing crystal surface. In this thesis we study this influence in detail using the NaCl

  10. Crystallization Thermodynamic and Kinetic Behaviors of Vitamin C in Batch Crystallizer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The bench-scale cooling crystallization for ternary solution of L-ascorbic acid (Vitamin C) was studied. The solid-liquid phase diagram of Vitamin C-water-ethanol system was obtained on the basis of differential scanning calorimeter (DSC) curves. The heat of crystallization of Vitamin C was calculated with the aid of quantitative analysis. According to the population balance equation under unsteady state, the rates of nucleation and growth were determined. The parameters of crystallization kinetics equations were estimated by regression of experimental data. Crystal morphology and size were determined with x-ray diffraction and TA Ⅱ Coulter Counter.

  11. Changes in calcium oxalate crystal morphology as a function of supersaturation

    Directory of Open Access Journals (Sweden)

    Mauricio Carvalho

    2004-06-01

    Full Text Available PURPOSE: To study the changes in calcium oxalate crystal morphology induced by different levels of supersaturation (SS in human urine. MATERIALS AND METHODS: Twenty-four hours urine samples from 5 normal men were collected. Each specimen was centrifuged and filtered. About 200 mL of each sample was dialyzed overnight. Aliquots of 2 mL of urine was then added to a 24-wells tissue culture plate and checked for crystal absence. Calcium oxalate crystals were precipitated from each sample by adding sodium oxalate and calcium chloride in sufficient quantities to induce spontaneous crystallization. Finally, each plate hole was examined with an inverted polarized microscope (X500 magnification. Initial SS of each sample relative to calcium oxalate was calculated using an iterative computer program. RESULTS: Crystal formation was connecte to relative calcium oxalate (CaOx SS. At SS of 10, small crystals of similar shape were formed, mainly CaOx dihydrate morphology. At SS of 30, there was an enormous increase in the number of crystals, that kept the same size. SS greater than 50 produced larger crystals with different shapes and multiple crystalline aggregates. Urine was able to tolerate, i.e., to avoid crystal formation, until SS ratios of approximately 10. CONCLUSIONS: Relative CaOx SS and the concentration ratio of calcium to oxalate are important determinanting factors of crystal morphology. Non-dialyzable urinary proteins can act as inhibitors and influence the structure of formed crystals. Additional studies from patients with kidney stones are needed in order to establish whether crystal size and habit distribution are different from crystals in normal urine.

  12. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes.

    Science.gov (United States)

    Liu, Jie; Lu, Xiaolong; Wu, Chunrui

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

  13. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride Membranes

    Directory of Open Access Journals (Sweden)

    Jie Liu

    2013-11-01

    Full Text Available Poly(vinylidene fluoride (PVDF membranes were prepared by non solvent induced phase separation (NIPS, melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR and X-ray diffraction (XRD were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO and differential scanning calorimetry (DSC separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites.

  14. Fe 2O 3 single crystals: hydrothermal growth, crystal chemistry and growth morphology

    Science.gov (United States)

    Demianets, L. N.; Pouchko, S. V.; Gaynutdinov, R. V.

    2003-11-01

    Hematite single crystals have been grown under hydrothermal conditions. The analysis of atomic structures of the {h k i l} faces has been made, and the sequence of the growth rate change has been explained on the basis of that analysis. Optical and AFM study show two main mechanisms of α-Fe 2O 3 growth. They are layer-by-layer growth and island growth. The morphological characteristics of {1 1 2¯ 0} surfaces are given. Large flat terraces with height h 100-150 nm, width d˜10000 nm are observed of the face surface. Terraces are composed from the steps ( h 15-65, d 100-1200 nm). AFM-images of small steps demonstrate that they consist of globules with rounded or elongated shapes. Typical heights of globules are 0.5-5 nm, and typical lengths are 30-60 nm. These globules are orderly packed on the face, the elongation being along [1 0 1¯ 0] direction.

  15. Morphology and fluorescence spectra of rubrene single crystals grown by physical vapor transport

    Energy Technology Data Exchange (ETDEWEB)

    Zeng Xionghui [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Zhang Deqiang [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Duan Lian [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Wang Liduo [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Dong Guifang [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China); Qiu Yong [Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084 (China)]. E-mail: qiuy@mail.tsinghua.edu.cn

    2007-05-15

    Rubrene single crystals with pentagon, hexagon, lath-like, and needle-like shape were grown by physical vapor transport. The morphology of surface and transect of rubrene crystals was characterized by optical microscope, atomic force microscope and scanning electron microscope. Monolayers and layer-like structures were observed on the rubrene crystal surface and in the interior of single crystals, respectively. Size and quality of rubrene crystals could be controlled by tuning growth parameters including source temperature, deposition temperature, and growth time. Compared with the emission peak at 555 nm of rubrene solution with the concentration of 10{sup -5} M, the emission peak of rubrene single crystals is at 649 nm with a shift of 94 nm. Hexagon etching pits with typical ladder-like structure were also observed on the (1 0 0) crystal plane and the density of dislocation lines is about 10{sup 3} cm{sup -2}.

  16. Effect of silk sericin on morphology and structure of calcium carbonate crystal

    Science.gov (United States)

    Zhao, Rui-Bo; Han, Hua-Feng; Ding, Shao; Li, Ze-Hao; Kong, Xiang-Dong

    2013-06-01

    In this paper, silk sericin was employed to regulate the mineralization of calcium carbonate (CaCO3). CaCO3 composite particles were prepared by the precipitation reaction of sodium carbonate with calcium chloride solution in the presence of silk sericin. The as-prepared samples were collected at different reaction time to study the crystallization process of CaCO3 by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that silk sericin significantly affected the morphology and crystallographic polymorph of CaCO3. With increasing the reaction time, the crystal phase of CaCO3 transferred from calcite dominated to vaterite dominated mixtures, while the morphology of CaCO3 changed from disk-like calcite crystal to spherical vaterite crystal. These studies showed the potential of silk sericin used as a template molecule to control the growth of inorganic crystal.

  17. Crystallization kinetics and morphology of poly(ferrocenyldimethylsilane)

    NARCIS (Netherlands)

    Lammertink, Rob G.H.; Hempenius, Mark A.; Vancso, G. Julius

    1998-01-01

    A series of poly(ferrocenyldimethylsilanes) were prepared via anionic ring-opening polymerization. The isothermal crystallization kinetics were investigated by means of differential scanning calorimetry and analyzed in terms of the Avrami equation. The value of the Avrami exponent is approximately 3

  18. The impact of crystal morphology on the thermal responses of ultrasonically-excited energetic materials

    Science.gov (United States)

    Miller, J. K.; Mares, J. O.; Gunduz, I. E.; Son, S. F.; Rhoads, J. F.

    2016-01-01

    The ability to detect explosive materials may be significantly enhanced with local increases in vapor pressure caused by an elevation of the materials' temperature. Recently, ultrasonic excitation has been shown to generate heat within plastic-bonded energetic materials. To investigate the impact of crystal morphology on this heating, samples of elastic binder are implanted with single ammonium perchlorate crystals of two distinct shape groups. Contact piezoelectric transducers are then used to excite the samples at ultrasonic frequencies. The thermal responses of the crystals are recorded using infrared thermography, and the rate of heating is estimated. Surface temperature increases up to 15 °C are found to arise after 2 s of excitation, with much higher heating levels expected near the inclusions themselves as demonstrated by the chemical decomposition of some crystals under favorable excitation conditions. The rates of heat generation are compared to various crystal morphology features through 2D estimates of length scale, perimeter and irregularity. It is observed that crystals grown in the lab, featuring sharp geometric facets, exhibit a higher probability of significant heat generation than inclusions with more spherical shapes. However, no statistical link is found between the rates of heat generation and the crystal morphology in those samples that do generate significant heating, likely because variations in surface roughness cannot be entirely eliminated during experimentation. It is hoped that this study will lead to a better understanding of the nature of heat generation in energetic materials from ultrasonic sources.

  19. MELTING CRYSTALLIZATION BEHAVIOR OF NYLON 66

    Institute of Scientific and Technical Information of China (English)

    Qing-xin Zhang; Zhi-shen Mo

    2001-01-01

    Analysis of isothermal and nonisothermal crystallization kinetics of nylon 66 was carried out using differential scanning calorimetry (DSC). The commonly used Avrami equation and that modified by Jeziorny were used, respectively, to fit the primary stage of isothermal and nonisothermal crystallizations of nylon 66. In the isothermal crystallization process, mechanisms of spherulitic nucleation and growth were discussed. The lateral and folding surface free energies determined from the Lauritzen-Hoffman treatment are σ= 9.77 erg/cm2 and σe = 155.48 erg/cm2, respectively; and the work of chain folding is q = 33.14 kJ/mol. The nonisothermal crystallization kinetics of nylon 66 was analyzed by using the Mo method combined with the Avrami and Ozawa equations. The average Avrami exponent n was determined to be 3.45. The activation energies (ΔE) were determined to be -485.45 kJ/mol and -331.27 kJ/mol, respectively, for the isothermal and nonisothermal crystallization processes by the Arrhenius and the Kissinger methods.

  20. Ant Genetics: Reproductive Physiology, Worker Morphology, and Behavior.

    Science.gov (United States)

    Friedman, D A; Gordon, D M

    2016-07-01

    Many exciting studies have begun to elucidate the genetics of the morphological and physiological diversity of ants, but as yet few studies have investigated the genetics of ant behavior directly. Ant genomes are marked by extreme rates of gene turnover, especially in gene families related to olfactory communication, such as the synthesis of cuticular hydrocarbons and the perception of environmental semiochemicals. Transcriptomic and epigenetic differences are apparent between reproductive and sterile females, males and females, and workers that differ in body size. Quantitative genetic approaches suggest heritability of task performance, and population genetic studies indicate a genetic association with reproductive status in some species. Gene expression is associated with behavior including foraging, response to queens attempting to join a colony, circadian patterns of task performance, and age-related changes of task. Ant behavioral genetics needs further investigation of the feedback between individual-level physiological changes and socially mediated responses to environmental conditions. PMID:27050321

  1. Ant Genetics: Reproductive Physiology, Worker Morphology, and Behavior.

    Science.gov (United States)

    Friedman, D A; Gordon, D M

    2016-07-01

    Many exciting studies have begun to elucidate the genetics of the morphological and physiological diversity of ants, but as yet few studies have investigated the genetics of ant behavior directly. Ant genomes are marked by extreme rates of gene turnover, especially in gene families related to olfactory communication, such as the synthesis of cuticular hydrocarbons and the perception of environmental semiochemicals. Transcriptomic and epigenetic differences are apparent between reproductive and sterile females, males and females, and workers that differ in body size. Quantitative genetic approaches suggest heritability of task performance, and population genetic studies indicate a genetic association with reproductive status in some species. Gene expression is associated with behavior including foraging, response to queens attempting to join a colony, circadian patterns of task performance, and age-related changes of task. Ant behavioral genetics needs further investigation of the feedback between individual-level physiological changes and socially mediated responses to environmental conditions.

  2. Phylogenetic significance of composition and crystal morphology of magnetosome minerals

    OpenAIRE

    Mihály ePósfai; Christopher eLefèvre; Denis eTrubitsyn; Dennis A. Bazylinski; Richard eFrankel

    2013-01-01

    Magnetotactic bacteria (MTB) biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures, that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving magnetosomes that contain mineral and biological phases require multidisciplinary efforts. Here we use crystallographic, genomic and phylogenetic p...

  3. Phylogenetic significance of composition and crystal morphology of magnetosome minerals

    OpenAIRE

    Pósfai, Mihály; Lefèvre, Christopher T; Trubitsyn, Denis; Dennis A. Bazylinski; Frankel, Richard B.

    2013-01-01

    Magnetotactic bacteria (MTB) biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving magnetosomes that contain mineral and biological phases require multidisciplinary efforts. Here we use crystallographic, genomic and phylogenetic pe...

  4. THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE/CLAY COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Qin Zhang; Xiao-lin Gao; Ke Wang; Qiang Fu

    2004-01-01

    PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and panicle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and panicle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity.

  5. Phylogenetic significance of composition and crystal morphology of magnetosome minerals.

    Science.gov (United States)

    Pósfai, Mihály; Lefèvre, Christopher T; Trubitsyn, Denis; Bazylinski, Dennis A; Frankel, Richard B

    2013-01-01

    Magnetotactic bacteria (MTB) biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving magnetosomes that contain mineral and biological phases require multidisciplinary efforts. Here we use crystallographic, genomic and phylogenetic perspectives to review the correlations between magnetosome mineral habits and the phylogenetic affiliations of MTB, and show that these correlations have important implications for the evolution of magnetosome synthesis, and thus magnetotaxis. PMID:24324461

  6. Phylogenetic significance of composition and crystal morphology of magnetosome minerals

    Directory of Open Access Journals (Sweden)

    Mihály ePósfai

    2013-11-01

    Full Text Available Magnetotactic bacteria (MTB biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures, that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving magnetosomes that contain mineral and biological phases require multidisciplinary efforts. Here we use crystallographic, genomic and phylogenetic perspectives to review the correlations between magnetosome mineral habits and the phylogenetic affiliations of MTB, and show that these correlations have important implications for the evolution of magnetosome synthesis, and thus magnetotaxis.

  7. Modifying the growth morphology of aluminum crystals by magnetic mirror in a thermal plasma reactor

    International Nuclear Information System (INIS)

    Effect of magnetic fields on growth morphology of aluminum crystals was studied in a fluidized bed thermal plasma reactor assisted by magnetic mirrors. Aluminum crystals were precipitated in the reactor using aluminum powder or aluminum-graphite mixture as precursors. The absent of magnetic field was also studied for comparison. Products were characterized by scanning electron microscopy (SEM) and X-ray Diffraction (XRD). Results indicated that, regardless the precursor used, it was observed the presence of aluminum nanowires when the external magnetic mirror was applied, suggesting that magnetic fields are able to modify growth morphology at nanoscale

  8. Method for estimating the morphological significance of simple forms of crystals from X-ray data

    International Nuclear Information System (INIS)

    When developing V.I. Mikheev and I.I. Shafranovskii's method for estimating the morphological significance of faces of different simple forms from X-ray reflection intensities, a way to approximately evaluate the morphological significance of simple forms on crystals from the structure amplitudes of the corresponding atomic planes is proposed. The potential for this approach is demonstrated by the examples of marcasite and zircon.

  9. Atomic force microscopy studies on phase transitions and surface morphology transformation of CMTC crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, X.N.; Xu, D.; Yuan, D.R.; Sun, D.L.; Lu, M.K.; Jiang, M.H. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan (China)

    2002-11-01

    Atomic force microscopy (AFM) has been used to investigate the phase transitions and surface morphology transformation of cadmium mercury thiocyanate (CMTC) crystals, which are highly efficient nonlinear optical (NLO) materials for generating blue-violet light by laser frequency doubling. Amorphous aggregates at the crystalline steps become greatly contracted and much more crystalloid after the crystal was kept for one day. Elimination of dangling bonds, which lower the surface free energy at the crystal surface, and structural adjustment inside the crystal are assumed to cause this phase transition. Surface morphology transformations were also observed in CMTC crystals during and after multiple scanning by AFM tips. We have visualized the continuous translation process from two-dimensional nuclei to trigonal microcrystals with almost equal sizes during multiple scanning. In other cases, however, the surface morphology did not change at all during scanning, but became greatly altered hours after scanning. These experimental results suggest that reconstruction is a characteristic growth phenomenon on CMTC crystal surfaces. Reconstruction probably results from the formation of intervening metastable phases that have the potential to arrive at more stable stages; however, multiple scanning of AFM tips greatly affects this translation process. (orig.)

  10. MELTING AND CRYSTALLIZATION BEHAVIOR OF AN AROMATIC POLY (AZOMETHINE ETHER) WITH NON-LINEARLY SHAPED MOLECULAR CONFORMATIONS

    Institute of Scientific and Technical Information of China (English)

    HOU Jianan; XU Mao; LI Xiaofang; ZHANG Qizhen

    1995-01-01

    The melting and crystallization behavior have been investigated for an aromatic poly (azomethine ether)with non-linearly shaped molecular conformations.This polymer was found to undergo multiple melting processes and its phase transition behavior was influenced sensitively by the thermal history of sample. A significant difference between the polymer chain aggregation abilities of samples cooled from the different states was observed. The possible molecular morphology and aggregation models for describing the structures of this polymer were proposed and discussed. The crystallization behavior of the samples cooled from the partially isotropic state and the influence of cooling rate on it have also been examined with DSC.

  11. Comparative Analysis of Thermal Behavior, Isothermal Crystallization Kinetics and Polymorphism of Palm Oil Fractions

    Directory of Open Access Journals (Sweden)

    Bing Li

    2013-01-01

    Full Text Available Thermal behavior of palm stearin (PS and palm olein (PO was explored by monitoring peak temperature transitions by differential scanning calorimetry (DSC. The fatty acid composition (FAC, isothermal crystallization kinetics studied by pulsed Nuclear Magnetic Resonance (pNMR and isothermal microstructure were also compared. The results indicated that the fatty acid composition had an important influence on the crystallization process. PS and PO both exhibited more multiple endotherms than exotherms which showed irregular peak shapes. An increasing in cooling rate, generally, was associated with an increase in peak size. Application of the Avaimi equation to isothermal crystallization of PS and PO revealed different nucleation and growth mechanisms based on the Avrami exponents. PS quickly reached the end of crystallization because of more saturated triacylglycerol (TAG. The Avrami index of PS were the same as PO under the same isothermal condition at lower temperatrue, indicating that the crystallization mechanism of the two samples based on super-cooling state were the same. According to the polarized light microscope (PLM images, crystal morphology of PS and PO was different. With the temperature increased, the structure of crystal network of both PS and PO gradually loosened.

  12. Morphology, crystallization and dynamic mechanical properties of PA66/nano-SiO2 composites

    Indian Academy of Sciences (India)

    Huimin Lu; Xiangmin Xu; Xiaohong Li; Zhijun Zhang

    2006-10-01

    This article addresses the effect of nano-SiO2 on the morphology, crystallization and dynamic mechanical properties of polyamide 66. The influence of nano-SiO2 on the tensile fracture morphology of the nanocomposites was studied by scanning electron microscopy (SEM), which suggested that the nanocomposites revealed an extensive plastic stretch of the matrix polymer. The crystallization behaviour of polyamide 66 and its nanocomposites were studied by differential scanning calorimetry (DSC). DSC nonisothermal curves showed an increase in the crystallization temperature along with increasing degree of crystallinity. Dynamic mechanical properties (DMA) indicated significant improvement in the storage modulus and loss modulus compared with neat polyamide 66. The tan ä peak signifying the glass-transition temperature of nanocomposites shifted to higher temperature.

  13. Crystallization and Morphology of Autophobic Dewetted Poly(ε-caprolactone)-b-poly(L-lactide) Diblock Copolymer Ultrathin Films%Crystallization and Morphology of Autophobic Dewetted Poly(ε-caprolactone)-b-poly(L-lactide) Diblock Copolymer Ultrathin Films

    Institute of Scientific and Technical Information of China (English)

    严德荣; 黄海瑛; 何天白

    2012-01-01

    We have investigated the crystallization and morphological behaviors of poly(ε-caprolactone)-b-poly(L-lactide) (PCL-b-PLLA) in its autophobic dewetted ultrathin films (-11 nm) using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The autophobic dewetting process creates a well defined film geometry containing an extremely thin wetting layer (-4.5 nm) with densely distributed micrometer droplets atop, which re- stricts the primary nucleation process to occurring only in the droplets. In addition to the normally encountered flat-on lamellae, the growth of edge-on lamellae in such a thin wetting layer has been observed on both of two crys- tallization paths. In thermal crystallization, flat-on lamellae are favored at small supercoolings while edge-on la- mellae appear at very large supercoolings both in the droplets and the wetting layer. For cold crystallization, the edge-on lamellae can form easily in the droplets and grow into the wetting layer even at very small supercoolings. These observations are explained on the basis that the nucleation and lamellar orientation are strongly affected by the film geometry, the crystallization paths, and the applied supercoolings.

  14. The study of crystallization and interfacial morphology in polymer/carbon nanotube composites

    Science.gov (United States)

    Minus, Marilyn Lillith

    This study illustrates the ability of SWNT to nucleate and template polymer crystallization and orientation, and produce materials with improved properties and unique polymer morphologies. This research work focuses primarily on the physical interaction between single-wall carbon nanotubes (SWNT) and the flexible polymer system polyvinyl alcohol (PVA). Polymer crystallization in the near vicinity of SWNT (interphase) has been studied to understand the capability of SWNT in influence polymer morphology in bulk films and fibers. Fibrillar crystallization was achieved by shearing PVA/SWNT dispersions and resulted in the formation of oriented PVA/SWNT fibers or ribbons, while PVA solutions produce unoriented fibers. PVA single crystals were grown in PVA solutions as well as PVA/SWNT dispersions over a period of several months at room temperature (25°C). PVA single crystal growth in PVA/SWNT dispersions is templated by SWNT, and these crystals show the presence of new morphologies for PVA. PVA single crystals of differing morphology were also grown at elevated temperatures, and show morphology dependant electron beam irradiation resistance. Gel-spinning was used to produce PVA, and PVA/SWNT fibers where, PVA crystallization in the bulk fiber was observed. With 1 wt% SWNT loading in PVA, the fiber tensile strength increased from 1.6 GPa for the control PVA to 2.6 GPa for PVA/SWNT. Analysis of this data suggests stress of up to ˜120 GPa on the SWNT. This is the highest reported stress on the SWNT to date and confirm excellent reinforcement and load transfer of SWNT in the PVA matrix. Raman spectroscopy data show high SWNT alignment in the fiber where the I0*/I90* ratio is measured to be 106. High-resolution transmission electron microscopy (HR-TEM) is used to characterize polymer morphology near the polymer-SWNT interface for PVA/SWNT fibers. HR-TEM studies of Polymer/CNT composites show distinct morphological differences at the polymer-SWNT interface/interphase for

  15. A software tool to evaluate crystal types and morphological developments of accessory zircon

    Science.gov (United States)

    Sturm, Robert

    2014-08-01

    Computer programs for an appropriate visualization of crystal types and morphological developments of accessory zircon are not available hitherto. Usually, typological computations are conducted by using simple calculation tools or spread-sheet programs. In practice, however, high numbers of data sets including information of numerous zircon populations have to be processed and stored. The paper describes the software ZIRCTYP, which is a macro-driven program within the Microsoft Access database management system. It allows the computation of zircon morphologies occurring in specific rock samples and their presentation in typology diagrams. In addition, morphological developments within a given zircon population are presented (1) statistically and (2) graphically as crystal sequences showing initial, intermediate, and final growth stages.

  16. Effect of crystals and fibrous network polymer additives on cellular morphology of microcellular foams

    Science.gov (United States)

    Miyamoto, Ryoma; Utano, Tatsumi; Yasuhara, Shunya; Ishihara, Shota; Ohshima, Masahiro

    2015-05-01

    In this study, the core-back foam injection molding was used for preparing microcelluar polypropylene (PP) foam with either a 1,3:2,4 bis-O-(4-methylbenzylidene)-D-sorbitol gelling agent (Gel-all MD) or a fibros network polymer additive (Metablen 3000). Both agent and addiive could effectively control the celluar morphology in foams but somehow different ways. In course of cooling the polymer with Gel-all MD in the mold caity, the agent enhanced the crystal nucleation and resulted in the large number of small crystals. The crystals acted as effective bubble nucleation agent in foaming process. Thus, the agent reduced the cell size and increased the cell density, drastically. Furthermore, the small crystals provided an inhomogenuity to the expanding cell wall and produced the high open cell content with nano-scale fibril structure. Gell-all as well as Metablene 3000 formed a gel-like fibrous network in melt. The network increased the elongational viscosity and tended to prevent the cell wall from breaking up. The foaming temperature window was widened by the presence of the network. Especially, the temperature window where the macro-fibrous structure was formed was expanded to the higher temperature. The effects of crystal nucleating agent and PTFE on crystals' size and number, viscoelsticity, rheological propreties of PP and cellular morphology were compared and thorougly investigated.

  17. Morphological and mechanical characterization of composite calcite/SWCNT-COOH single crystals.

    Science.gov (United States)

    Calvaresi, Matteo; Falini, Giuseppe; Pasquini, Luca; Reggi, Michela; Fermani, Simona; Gazzadi, Gian Carlo; Frabboni, Stefano; Zerbetto, Francesco

    2013-08-01

    A growing number of classes of organic (macro)molecular materials have been trapped into inorganic crystalline hosts, such as calcite single crystals, without significantly disrupting their crystalline lattices. Inclusion of an organic phase plays a key role in enhancing the mechanical properties of the crystals, which are believed to share structural features with biogenic minerals. Here we report the synthesis and mechanical characterization of composite calcite/SWCNT-COOH single crystals. Once entrapped into the crystals SWCNT-COOH appeared both as aggregates of entangled bundles and nanoropes. Their observation was possible only after crystal etching, fracture or FIB (focused ion beam) cross-sectioning. SWCNT-COOHs occupied a small volume fraction and were randomly distributed into the host crystal. They did not strongly affect the crystal morphology. However, although the Young's modulus of composite calcite/SWCNT-COOH single crystals was similar to that of pure calcite their hardness increased by about 20%. Thus, SWCNT-COOHs provide an obstacle against the dislocation-mediated propagation of plastic deformation in the crystalline slip systems, in analogy with the well-known hardness increase in fiber-reinforced composites.

  18. Effect of solvent on crystallization behavior of xylitol

    Science.gov (United States)

    Hao, Hongxun; Hou, Baohong; Wang, Jing-Kang; Lin, Guangyu

    2006-04-01

    Effect of organic solvents content on crystallization behavior of xylitol was studied. Solubility and crystallization kinetics of xylitol in methanol-water system were experimentally determined. It was found that the solubility of xylitol at various methanol content all increases with increase of temperature. But it decreases when increasing methanol content at constant temperature. Based on the theory of population balance, the nucleation and growth rates of xylitol in methanol-water mixed solvents were calculated by moments method. From a series of experimental population density data of xylitol gotten from a batch-operated crystallizer, parameters of crystal nucleation and growth rate equations at different methanol content were got by the method of nonlinear least-squares. By analyzing, it was found that the content of methanol had an apparent effect on nucleation and growth rate of xylitol. At constant temperature, the nucleation and growth rate of xylitol all decrease with increase of methanol content.

  19. Outline of Classical and Current Approaches to the Research of Morphology of Selected Mineral Crystals in China (CD-ROM)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The research on morphology of mineral crystals in China includes classical goniometry of 100 minerals such as hsianghualite, orthobrannerite, jamesonite and bertrandite and surface microtopography of 20 minerals such as wolframite and diamond, among which 5 new minerals and 34 uranium minerals were discovered and measured by Chinese mineralogists. These have enriched mineralogy and crystal morphology and strengthened the study of information of morphological genesis.

  20. Development of simultaneous control of polymorphism and morphology in indomethacin crystallization

    Science.gov (United States)

    Wada, Shuichi; Kudo, Shoji; Takiyama, Hiroshi

    2016-02-01

    In order to improve the bioavailability, it is desired to obtain the polymorph which has the higher solubility of indomethacin (IMC α-form). However, when α-form crystals were obtained by conventional anti-solvent crystallization, the stirring operation could not be continued because cotton agglomerates were formed in the solution. In order to simultaneously satisfy the bioavailability of IMC and the operability of IMC production, the modification of the morphology (external shape) of α-form agglomerates is important. So, the purpose of this present study is the development of the crystallization method. In order to modify the cotton agglomerates, the anti-solvent crystallization was carried out by using electrolyte aqueous solution (NaCl aq. solution) as the anti-solvent. By using the electrolyte aqueous solution, the liquid-liquid phase separation (LLPS) was observed depending on the solution composition. From the experimental results, under the condition both of high electrolyte concentration and of high stirring speed, dispersion of droplets was obtained, and spherical agglomerates of α-form were formed in the slurry. The stirring operation could be continued in the slurry because the modification of α-form cotton agglomerates was achieved. So, the simultaneous control method of the polymorphism and the morphology in IMC crystallization was realized.

  1. Domain morphology controlled crystal habits in PbTiO{sub 3} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dudhe, C.M., E-mail: chandraguptadudhe@gmail.com; Khambadkar, S.J.

    2015-11-05

    Various crystal habits and associated domain structures in PbTiO{sub 3} nanocrystals synthesized by a modified sol–gel method have been studied. Structural and morphological characterizations of synthesized nanoparticles have been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found from the -z coordinates of O{sub 1} and O{sub 2} that the Ti–O{sub 6} octahedra were distorted slightly, favorable for the ferroelectric nature. TEM images show butterfly like, plate like, irregular sphere like and oval-shaped habits of the nanocrystals. 90° and 180° domain structures in these crystal habits were explored from their morphologies and appearance in the field of views. The mutual association between the crystal habit and the direction spontaneous polarization P{sub s} due to domain structures was explored. Domain wall energies of 90° and 180° domains were also estimated from the kinetic process of domain nucleation. - Highlights: • Various crystal habits of PbTiO{sub 3} nanoparticles were examined by TEM. • 90° and 180° domains were explored in the nanocrystal. • Crystal habits and domain structures were correlated. • Domain wall energies were estimated.

  2. Crystallization behavior and microstructural characterization of drug/polymer systems

    Science.gov (United States)

    Zhu, Qing

    Solid dispersions of the active pharmaceutical ingredient (API) in a polymeric matrix have received extensive attention as a potential approach to increase the dissolution rate of the API. Among different types of solid dispersions, polyethylene glycol (PEG) based semicrystalline solid dispersions have attracted considerable interest, for the reason that PEG enables the delivery of most APIs with low aqueous solubility. However, there are still limitations that restrict the application of this technique for drug formulations. One main concern is the reproducibility of the physicochemical properties of the solid dispersions during scale-up and storage. Additionally, the mechanism by which the dissolution rate is enhanced is still unclear. These are all related to the microstructure of the solid dispersions. Therefore, the purpose of this project is to have a fundamental understanding of the crystallization behavior and microstructural evolution of API/PEG solid dispersions. The model API was comelted with PEG and solidified at predetermined temperatures. The effect of the physicochemical properties of the APIs, polymer matrix and preparation conditions on the crystallization behavior and structure were investigated, using wide-angle X-ray scattering, small-angle X-ray scattering, scanning electron microscopy, atomic force microscopy and second harmonic imaging microscopy. When API/PEG solid dispersions were formed using different APIs, it was found that, for the fast crystallizing APIs (e.g. naproxen), the interaction between the API and the PEG matrix slowed down the crystallization rate of naproxen. For the slow crystallizing APIs (e.g. ibuprofen), crystalline PEG acted as heterogeneous nuclei to speed up the onset of crystallization. It was also found that, APIs with strong interaction in PEG (e.g. Naproxen/PEG) favored the interlamellar incorporation of naproxen in PEG matrix before naproxen crystallized. When the naproxen/PEG solid dispersions are prepared at

  3. Effect of nucleation layer morphology on crystal quality, surface morphology and electrical properties of AlGaN/GaN heterostructures

    Institute of Scientific and Technical Information of China (English)

    Duan Huantao; Hao Yue; Zhang Jincheng

    2009-01-01

    Nucleation layer formation is a key factor for high quality gallium nitride (GaN) growth on a sapphire substrate. We found that the growth rate substantially affected the nucleation layer morphology, thereby having a great impact on the crystal quality, surface morphology and electrical properties of AIGaN/GaN heterostructures on sapphire substrates. A nucleation layer with a low growth rate of 2.5 nm/min is larger and has better coalescence than one grown at a high growth rate of 5 nm/min. AIGaN/GaN heterostructures on a nucleation layer with low growth rate have better crystal quality, surface morphology and electrical properties.

  4. Nanoscale viscoplastic behavior of smectic liquid crystals and its application in nanolithography

    International Nuclear Information System (INIS)

    We report a unique combination of properties of smectic liquid crystal films that can be described as a viscoplastic behavior on the nanoscale: On the one hand, the films preserve imprinted surface patterns despite being permeated by a directed molecular flow of the film material. On the other hand, their surface morphology can easily be manipulated using an atomic force microscopy tip. Our results demonstrate a controlled molecular-scale deposition of material on the film surface, thereby enabling nanolithographic surface modification of a fluid material

  5. Nanoscale viscoplastic behavior of smectic liquid crystals and its application in nanolithography

    Science.gov (United States)

    Schulz, Benjamin; Steffen, Paul; Bahr, Christian

    2014-02-01

    We report a unique combination of properties of smectic liquid crystal films that can be described as a viscoplastic behavior on the nanoscale: On the one hand, the films preserve imprinted surface patterns despite being permeated by a directed molecular flow of the film material. On the other hand, their surface morphology can easily be manipulated using an atomic force microscopy tip. Our results demonstrate a controlled molecular-scale deposition of material on the film surface, thereby enabling nanolithographic surface modification of a fluid material.

  6. GROWTH KINETICS, CRYSTAL STRUCTURE, AND MORPHOLOGY OF OMVPE-GROWN HOMOEPITAXIAL CdTe

    OpenAIRE

    Snyder, D.; Sides, P.; Ko, E.; Mahajan, S.

    1991-01-01

    The growth rate, crystal structure, morphology, and electronic properties of homoepitaxial CdTe grown by OMVPE in an impinging jet reactor were investigated. Under operating conditions where surface reactions controlled the rate, the deposition rate depended on the diethyltelluride partial pressure to the .8 power and on the dimethylcadmium partial pressure to the .2 power, approximately. Cadmium was easily adsorbed and was ubiquitous on the surface during deposition ; tellurium was relativel...

  7. CRYSTALLIZATION BEHAVIOR, THERMAL AND MECHANICAL PROPERTIES OF PHBV/GRAPHENE NANOSHEET COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Bing-jie Wang; Yu-jie Zhang; Jian-qiang Zhang; Qu-ting Gou; Zong-bao Wang; Peng Chen; Qun Gu

    2013-01-01

    Biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/graphene nanosheet (GNS) composites were prepared via a solution-casting method at low GNS loadings in this work.Transmission electron microscopy revealed that a fine dispersion of GNSs was achieved in the PHBV matrix.The thermal properties of the nanocomposites were investigated by thermogravimetric analysis,and the results showed that the thermal stability of PHBV was significantly improved with a very low loading of GNSs.Nonisothermal melts crystallization behavior,spherulitic morphology and crystal structure of neat PHBV and the PHBV/GNSs nanocomposites were investigated,and the experimental results indicated that crystallization behavior of PHBV was enhanced by the presence of GNSs due to the heterogeneous nucleation effect;however,the two-dimensional (2D) GNSs might restrict the mobility of the PHBV chains in the process of crystal growing.Dynamic mechanical analysis studies showed that the storage modulus of the PHBV/GNSs nanocomposites was greatly improved.

  8. Hydrothermal Synthesis of Zeolitic Imidazolate Frameworks-8 (ZIF-8) Crystals with Controllable Size and Morphology

    KAUST Repository

    Lestari, Gabriella

    2012-05-01

    Zeolitic imidazolate frameworks (ZIFs) is a new class of metal-organic frameworks (MOFs) with zeolite-like properties such as permanent porosity, uniform pore size, and exceptional thermal and chemical stability. Until recently, ZIF materials have been mostly synthesized by solvothermal method. In this thesis, further analysis to tune the size and morphology of ZIF-8 is done upon our group’s recent success in preparing ZIF-8 crystals in pure aqueous solutions. Compositional parameters (molar ratio of 2-methylimidazole/Zn2+, type of zinc salt reagents, reagent concentrations, addition of surfactants) as well as process parameters (temperature and time) were systematically investigated. Upon characterizations of as-synthesized samples by X-ray powder diffraction, thermal gravimetric analysis, N2 adsorption, and field-emission scanning electron microscope, the results show that the particle size and morphology of ZIF-8 crystals are extremely sensitive to the compotional parameters of reagent concentration and addition of surfactants. The particle size and morphology of hydrothermally synthesized ZIF-8 crystals can be finely tuned; with the size ranging from 90 nm to 4 μm and the shape from truncated cubic to rhombic dodecahedron.

  9. Wide-gap nitrides: from growth morphology to device behavior.

    Science.gov (United States)

    Buongiorno Nardelli, Marco

    1998-03-01

    With the aim to improve understanding of the basic mechanisms that underline growth and device behavior in nitride systems, we have carried out extensive ab initio theoretical investigations of surfaces and interfaces of wide-gap nitrides. The phenomena that we have studied include electronic and transport properties in nitride-based multiquantum wells, as influenced by band offsets and polarization-induced electric fields, and the effect of growth conditions on the surface morphology of the primary growth faces of GaN. Interface properties such as band offsets between the different epilayers in a heterojunction have a major impact on the carrier transport properties both along and across the interface. Since heterojunctions of the nitrides are lattice-mismatched, the band offset can be tuned by changing the substrate material, which introduces strain. The effects of the pyroelectric and piezoelectric fields naturally present in wurtzite nitrides have also been analyzed. They are strong enough to significantly reduce the interband recombination rate and intrinsically limit the lasing power of an ideal multiple quantum well blue laser. During the growth, the surface morphology of the substrate is important. On the Ga-terminated surface under Ga-rich (N-rich) conditions, a Ga-adatom (N-adatom) reconstruction is the most stable 2×2 reconstruction. A N atom near the N-terminated surface spontaneously forms an N2 molecule, which is weakly bound to a vacancy on the substrate. At the high temperatures under which growth takes place, this will result in N2 desorption and subsequent reconstructions. We have also investigated H and Mg adsorption on the (0001) surface. H stabilizes the ideally cleaved surface irrespective of polarity, and the surface states associated with its adsoption have been identified. Although Mg is the most important p-type dopant of GaN, its incorporation during MBE growth has been difficult. We discuss its incorporation and the behavior of

  10. Morphological tranformation of calcite crystal growth by prismatic "acidic" polypeptide sequences.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I; Giocondi, J L; Orme, C A; Collino, J; Evans, J S

    2007-02-13

    Many of the interesting mechanical and materials properties of the mollusk shell are thought to stem from the prismatic calcite crystal assemblies within this composite structure. It is now evident that proteins play a major role in the formation of these assemblies. Recently, a superfamily of 7 conserved prismatic layer-specific mollusk shell proteins, Asprich, were sequenced, and the 42 AA C-terminal sequence region of this protein superfamily was found to introduce surface voids or porosities on calcite crystals in vitro. Using AFM imaging techniques, we further investigate the effect that this 42 AA domain (Fragment-2) and its constituent subdomains, DEAD-17 and Acidic-2, have on the morphology and growth kinetics of calcite dislocation hillocks. We find that Fragment-2 adsorbs on terrace surfaces and pins acute steps, accelerates then decelerates the growth of obtuse steps, forms clusters and voids on terrace surfaces, and transforms calcite hillock morphology from a rhombohedral form to a rounded one. These results mirror yet are distinct from some of the earlier findings obtained for nacreous polypeptides. The subdomains Acidic-2 and DEAD-17 were found to accelerate then decelerate obtuse steps and induce oval rather than rounded hillock morphologies. Unlike DEAD-17, Acidic-2 does form clusters on terrace surfaces and exhibits stronger obtuse velocity inhibition effects than either DEAD-17 or Fragment-2. Interestingly, a 1:1 mixture of both subdomains induces an irregular polygonal morphology to hillocks, and exhibits the highest degree of acute step pinning and obtuse step velocity inhibition. This suggests that there is some interplay between subdomains within an intra (Fragment-2) or intermolecular (1:1 mixture) context, and sequence interplay phenomena may be employed by biomineralization proteins to exert net effects on crystal growth and morphology.

  11. Morphological evolution of inorganic crystal into zigzag and helical architectures with an exquisite association of polymer: a novel approach for morphological complexity.

    Science.gov (United States)

    Oaki, Yuya; Imai, Hiroaki

    2005-02-01

    The morphology of potassium sulfate (K(2)SO(4)) crystals grown in a viscous polymer solution of poly(acrylic acid) (PAA) was remarkably changed from the tilted columnar assembly into zigzag and helical architectures with increasing PAA concentration. The habit modification of orthorhombic K(2)SO(4) with adsorption of PAA molecules on a specified crystal face fundamentally led to the formation of tilted unit crystals. Concurrently with the habit modification, a diffusion-limited condition controlling the assembly of tilted units was achieved in the presence of PAA molecules in the matrix. Various complex morphologies, including zigzag and helical assembly, emerged through the formation of twinned crystals with the variation of the diffusion condition. Understanding the morphogenesis observed in this report would provide a novel approach for sophisticated crystal design by using an exquisite association of organic and inorganic materials. PMID:15667161

  12. Effect of pressure and hydrogen flow in nucleation density and morphology of graphene bidimensional crystals

    Science.gov (United States)

    Chaitoglou, S.; Bertran, E.

    2016-07-01

    In this paper we present new results concerning the growth of graphene by low pressure chemical vapor deposition on polycrystalline copper foils and using methane as carbon precursor. We have studied the role of hydrogen and pressure in graphene growth on substrates of polycrystalline copper foil and we have examined how they affect the nucleation density and the size of graphene bidimensional crystals. For that, small ranges of pressure (between 10 and 30 Pa) and hydrogen flow (between 10 and 20 sccm) were explored. In addition, the antagonism between two of the main effects of hydrogen was studied. Hydrogen promotes the growth but, at the same time, applies an intense dry etching during the growth process of graphene. The challenge of the present study is to find the equilibrium between these two effects so that, the growth of highly ordered crystals on copper becomes possible. The results reveal that the total pressure during the growth process of graphene affects the size as well as the nucleation density of the graphene bidimensional crystals on polycrystalline copper. Besides, the hydrogen flow affects the morphology and quality of the graphene layer. An important parameter for a correct interpretation of the results is the change of the partial pressure ratio, / , during the growth process under a constant flow of H2 and CH4. Dendritic graphene crystals with lobe lengths around 30 μm along with a nucleation density of 25 nuclei/10 000 μm2 were obtained in the studied technological conditions, which corroborates that a low nucleation of graphene is required to obtain large graphene islands and a low number of crystal boundaries. Raman spectroscopy and scanning electron microscopy evidenced the effects of hydrogen on the characteristics of growth and morphology of the graphene dendritic bidimensional crystals.

  13. Morphology Of Diesel Soot Residuals From Supercooled Water Droplets And Ice Crystals: Implications For Optical Properties

    Energy Technology Data Exchange (ETDEWEB)

    China, Swarup; Kulkarni, Gourihar R.; Scarnatio, Barbara; Sharma, Noopur; Pekour, Mikhail S.; Shilling, John E.; Wilson, Jacqueline M.; Zelenyuk, Alla; Chand, Duli; Liu, Shang; Aiken, Allison; Dubey, Manvendra K.; Laskin, Alexander; Zaveri, Rahul A.; Mazzoleni, Claudio

    2015-11-04

    Freshly emitted soot particles are fractal-like aggregates, but atmospheric processing often transforms their morphology. Morphology of soot particles plays an important role in determining their optical properties, life cycle and hence their effect on Earth’s radiative balance. However, little is known about the morphology of soot particles that participated in cold cloud processes. Here we report results from laboratory experiments that simulate cold cloud processing of diesel soot particles by allowing them to form supercooled droplets and ice crystals at -20 and -40°C, respectively. Electron microscopy revealed that soot residuals from ice crystals were more compact (roundness~0.55) than those from supercooled droplets (roundness ~0.45), while nascent soot particles were the least compact (roundness~0.41). Optical simulations using the discrete dipole approximation showed that the more compact structure enhances soot single scattering albedo by a factor up to 1.4, thereby reducing the top-of-the-atmosphere direct radiative forcing by ~63%. These results underscore that climate models should consider the morphological evolution of soot particles due to cold cloud processing to improve the estimate of direct radiative forcing of soot.

  14. Crystallization kinetics and morphology of melt spun poly(ethylene terephthalate nanocomposite fibers

    Directory of Open Access Journals (Sweden)

    R. R. Hegde

    2013-10-01

    Full Text Available Natural nanoclay closite Na+ incorporated melt spun poly(ethylene terephthalate (PET fibers were investigated for crystallization kinetics and morphology. Nature of clay dispersion and nanocomposite morphology were assessed using wide angle X-ray diffraction (WAXD and transmission electron microscopy (TEM. Fiber mechanical properties were measured using single fiber tensile test. Combination of scanning electron microscopy (SEM and energy dispersive spectroscopy (EDS was used to investigate the fiber failure mode. Among nanocomposite PET fibers, sample with 1% clay performed better. WAXD and TEM micrographs of the fibers revealed intercalated and delaminated morphology. Size of agglomerate increased with percentage of add-on. SEM surface images showed significant variation in fiber diameter, voids and imperfections. Cross-sections of fractured surfaces revealed the presence of clay agglomerates at failure spots. Nanoclay reinforcement did not incur mechanical property benefits due to increase in voids and agglomerates in fiber section, especially at loading levels higher than one percent.

  15. Thermal properties and crystallization behavior of thermoplastic starch/poly(ɛ-caprolactone) composites.

    Science.gov (United States)

    Cai, Jie; Xiong, Zhouyi; Zhou, Man; Tan, Jun; Zeng, Fanbing; Meihuma; Lin, Shun; Xiong, Hanguo

    2014-02-15

    TPS/PCL composites were prepared by PCL melt blending with modified corn starch. The structure, thermal properties, morphology and crystallization behavior of these composites were investigated by FTIR, TGA, SEM, XRD and DSC. FTIR confirmed the existence of the interaction between PCL and TPS, whereas TGA showed that the thermal stability was decreased by the addition of TPS. Meanwhile, SEM showed a weak interfacial adhesion with increasing TPS. According to the Avrami theory, TPS functioned as a nucleating agent to improve the crystallinity rate of PCL. However, the XRD analysis revealed that the crystallinity decreased. At the same time, the ΔE(a) of the composites was higher than those of neat PCL. These changes in values all indicated that mobility constraints existed in the PCL chains with the increasing of TPS, which leaded to a drop in the crystallization ability of PCL. PMID:24507343

  16. Morphology and Efficiency of a Specialized Foraging Behavior, Sediment Sifting, in Neotropical Cichlid Fishes

    OpenAIRE

    Hernán López-Fernández; Jessica Arbour; Stuart Willis; Crystal Watkins; Honeycutt, Rodney L.; Winemiller, Kirk O.

    2014-01-01

    Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis...

  17. Additives effects on crystallization and morphology in a novel caustic aluminate solution decomposition process

    Institute of Scientific and Technical Information of China (English)

    Ying ZHANG; Sbili ZHENG; Yifei ZHANG; Hongbin XU; Yi ZHANG

    2009-01-01

    A novel process of caustic aluminate solution decomposition by alcohol medium was developed by the Institute of Process Engineering, Chinese Academy of Sciences in order to solve the problem of low decomposi-tion ratio in the traditional Bayer seeded hydrolysis process. In this research, effects of additives on the crystallization ratio, secondary particle size and morphol-ogy of aluminum hydroxide in the new process were studied to obtain high-quality products. On the basis of primary selection of additives, an orthogonal design L9(34)was used as a chemometric method to investigate the effects of additives. The studied parameters include the reaction style, quantity of additives, caustic soda concen-tration, as well as the combination manner. The crystal-lization ratios of sodium aluminate solution and crystal size of aluminum hydroxide, determined by ICP-OES, SEM and MLPSA (Malvern Laser Particle Size Analyzer), were used to evaluate the effects of the additives. The results showed that different combination manners could promote agglomeration or dispersion. An additive composed by Tween 80 and PEG 200 could promote agglomeration,while a spot of PEG species had a relatively strong dispersion effect. However, the additives had little effects on the crystallization ratios. According to the Raman spectra result, the added alcohol medium might serve as a kind of solvent.

  18. Synthesis, growth, morphology and characterization of ferroelectric glycine phosphite single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Devi, K. Renuka; Srinivasan, K. [Crystal Growth Laboratory, Department of Physics, School of Physical Sciences, Bharathiar University, Tamil Nadu (India)

    2011-12-15

    Glycine phosphite (NH{sub 3}CH{sub 2}COO.H{sub 3}PO{sub 3}), a potential ferroelectric material, was grown as single crystals from aqueous solutions by slow evaporation and slow cooling methods. Laboratory synthesized title compound was purified by recrystallization method and confirmed by Fourier transform infrared and Laser Raman studies. Temperature dependent solubility in double distilled water in the range between 288 and 328 K was determined by gravimetric method. Morphological importance of various growth faces were studied by optical goniometry. Powder x-ray diffraction study performed on the grown crystals confirms the crystal system and lattice parameters of the unit cell. Optical transparency of the grown crystals in the ultraviolet-visible -near infrared region was studied by spectroscopic method. Thermal stability of the grown crystals in the temperature region above ambient until melting was studied using differential scanning calorimetry. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Prediction of crystal morphology of cyclotrimethylene trinitramine in the solvent medium by computer simulation: a case of cyclohexanone solvent.

    Science.gov (United States)

    Chen, Gang; Xia, Mingzhu; Lei, Wu; Wang, Fengyun; Gong, Xuedong

    2014-12-11

    The crystal morphology of the energetic material cyclotrimethylene trinitramine (also known as RDX) influenced by the solvent effect was investigated via molecular dynamics simulation. The modified attachment energy (MAE) model was established by incorporating the growth parameter-solvent term. The adsorption interface models were used to study the adsorption interactions between solvent and RDX surfaces. The RDX crystal morphology grown from the cyclohexanone (CYC) solvent as a case investigation was calculated by the MAE model. The calculation results indicated that, due to the effect of CYC solvent, (210) and (111) faces had the greatest morphological importance on the final RDX crystal, while the morphological importance of (020), (002), and (200) faces were reduced. The predicted RDX morphology was in reasonable agreement with the observed experiment result.

  20. Microstructure, morphology, adhesion and tribological behavior of sputtered niobium carbide and bismuth films on tool steel

    Directory of Open Access Journals (Sweden)

    Laura Angélica Ardila Rodríguez

    2014-11-01

    Full Text Available Normal 0 21 false false false ES-CO X-NONE AR-SA Normal 0 21 false false false ES-CO X-NONE AR-SA NbC, Bi and Bi/NbC coatings were deposited on AISI M2 steel substrates using unbalanced magnetron sputtering at room temperature with zero bias voltage. Were studied the phase structure, the morphology, the adhesion and the tribological behavior of the three coatings. The niobium carbide film crystallized in the NbC cubic structure, and the bismuth layers had a rhombohedral phase with random orientation. The NbC coating had a smooth surface with low roughness, while the Bi layers on steel and on NbC coating had higher roughness and a morphology composed of large particles. By using a ductile Nb interlayer good adhesion between the NbC coating and the steel substrate was achieved. The Bi coating had better adhesion with the NbC layer than with the steel substrate. The tribological performance of the Bi coating on steel was not satisfactory, but according to the preliminary results, the produced NbC and Bi/NbC coatings have the potential to improve the tribological performance of the steel.

  1. Crystallization Behavior of Phosphate Glasses with Hydrophobic Coating Materials

    Directory of Open Access Journals (Sweden)

    Jaeyeop Chung

    2015-01-01

    Full Text Available We analyzed the effect of the addition of Li2O3, TiO2, and Fe2O3 on the crystallization behavior of P2O5–CaO–SiO2–K2O glasses and the effect of the crystallization behavior on the roughness and hydrophobicity of the coated surface. Exothermic behavior, including a strong exothermic peak in the 833–972 K temperature range when Fe2O3, TiO2, or Li2O3 was added, was confirmed by differential thermal analysis. The modified glass samples (PFTL1–3 showed diffraction peaks when heated at 1073 and 1123 K for 5 min; the crystallized phase corresponds to Fe3(PO42, that is, graftonite. We confirmed that the intensity of the diffraction peaks increases at high temperatures and with increasing Li2O3 content. In the case of the PFTL3 glass, a Li3Fe2(PO42 phase, that is, trilithium diiron(III tris[phosphate(V], was observed. Through scanning electron microscopy and the contact angles of the surfaces with water, we confirmed that the increase in surface roughness, correlated to the crystallization of the glass frit, increases hydrophobicity of the surface. The calculated values of the local activation energies for the growth of Fe3(PO42 on the PTFL1, PTFL2, and PFTL3 glass were 237–292 kJ mol−1, 182–258 kJ mol−1, and 180–235 kJ mol−1.

  2. Morphological tuning and enhanced luminescence of NaEuF4 nano-/submicro-crystals

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • NaEuF4 nano-/submicro-crystals were prepared via hydrothermal process. • The pH and Cit3−/Eu3+ ratio have an important role in the growth of NaEuF4. • Enhanced luminescence was observed in NaEuF4 spheres with smaller size. • J–O theory was used for analysis of luminescent properties of NaEuF4 phosphor. - Abstract: NaEuF4 nano-/submicro-crystals with various morphologies including regular nano-spheres, submicro-spheres, submicro-spindles and hexagonal submicro-rods were prepared through a facile hydrothermal process by adjusting the pH value and the molar ratio of Na3Cit/Eu3+ in the precursor solution. The resultants were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and photoluminescence spectroscopy (PL). The possible formation mechanisms for the morphology-varied NaEuF4 crystals were proposed based on the FE-SEM observation. The luminescent properties of NaEuF4 spheres with different particle size were studied. It was found that the luminescent intensities of NaEuF4 spheres increase with the decrease of particle size. Finally, the mechanism of luminescent enhancement was discussed

  3. Micromechanical Behavior of Single-Crystal Superalloy with Different Crystal Orientations by Microindentation

    Directory of Open Access Journals (Sweden)

    Jinghui Li

    2015-01-01

    Full Text Available In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001, (215, (405, and (605, microindentation test (MIT was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardness H, Young’s modulus E, yield stress σy, strain hardening component n, and tensile strength σb, can be obtained from load-displacement relations. H and E of four different crystal planes evidently decrease with the increase of h. The reduction of H is due to dislocation hardening while E is related to interplanar spacing and crystal variable. σy of (215 is the largest among four crystal planes, followed by (605, and (001 has the lowest value. n of (215 is the lowest, followed by (605, and that of (001 is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.

  4. Morphology, Growth Process and Symmetry of {0001} Face on Yb:YAl3(BO3)4 Crystal

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The {0001} face develops on the habit of self-frequency doubling laser crystal Yb: YAl3(BO3)4 (YbYAB) only under high growth rate condition, and its morphology is rough. To study the growth mechanism of {0001} face, we have observed the growth morphology on {0001} polishing section by atomic force microscopy (AFM). A series of AFM images captured in different growth durations on the {0001} polishing section reflect the crystal growth process. It is shown that the growth morphology on the {0001} polishing section was rough with many hillocks at the first growth stage, and it can become smooth finally, although the growth morphology on the {0001} face developed naturally on YbYAB crystal habit is always rough. On the smooth {0001} surface formed at the last growth stage, there are some triangular pits. This fact is different from that of hillocks in most crystal growth morphologies. AFM can easily distinguish the pits or hillocks on the surface, but differential interfere contrast microscopy (DIC) can not do. The orientation of the triangular pits is just the opposite to the triangular {0001} faces. The chemical etching pattern is also composed of this kind of triangular pits. These growth morphology and etching pattern of the {0001} faces show 3m symmetry, but the point group of YbYAB crystal is 32. The symmetric contradiction between morphology and point group does not exist for quartz, although which has the same point group as YbYAB. From quartz {0001} surface morphology we can distinguish the right form or left form of the crystal, but from YbYAB {0001} surface morphology we can not do. The reason for the symmetric contradiction between YbYAB {0001} surface morphology and its point group is not known yet.

  5. Morphology and non-isothermal crystallization kinetics of CuInS{sub 2} nanocrystals synthesized by solvo-thermal method

    Energy Technology Data Exchange (ETDEWEB)

    Majeed Khan, M.A., E-mail: majeed_phys@yahoo.co.in [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Kumar, Sushil [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055 (India); Alsalhi, M.S. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Department of Physics and Astronomy, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamed, Maqusood [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Alhoshan, Mansour [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Chemical Engineering Department, King Saud University, Riyadh 11451 (Saudi Arabia); Alrokayan, Salman A. [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451 (Saudi Arabia); Ahamad, Tansir [Department of Chemistry, King Saud University, Riyadh 11451 (Saudi Arabia)

    2012-03-15

    Nanocrystals of copper indium disulphide (CuInS{sub 2}) were synthesized by a solvo-thermal method. The structure, morphology and non-isothermal crystallization kinetic behavior of samples were investigated using X-ray diffraction, field emission scanning electron microscopy, field emission transmission electron microscopy, thermogravimetric analysis and differential thermal analysis techniques. Non-isothermal measurements at different heating rates were carried out and the crystallization kinetics of samples were analyzed using the most reliable non-isothermal kinetic methods. The kinetic parameters such as glass transition temperature, thermal stability, activation energy, Avrami exponent etc. were evaluated. - Highlights: Black-Right-Pointing-Pointer CuInS{sub 2} nanocrystals have scientific and technological importance. Black-Right-Pointing-Pointer Samples have been prepared by solvo-thermal method. Black-Right-Pointing-Pointer Synthesized samples exhibit excellent morphology and thermal properties. Black-Right-Pointing-Pointer Investigated properties may be utilized in design and fabrication of solar cell devices.

  6. The relationship between morphological and behavioral mimicry in hover flies (Diptera: Syrphidae).

    Science.gov (United States)

    Penney, Heather D; Hassall, Christopher; Skevington, Jeffrey H; Lamborn, Brent; Sherratt, Thomas N

    2014-02-01

    Palatable (Batesian) mimics of unprofitable models could use behavioral mimicry to compensate for the ease with which they can be visually discriminated or to augment an already close morphological resemblance. We evaluated these contrasting predictions by assaying the behavior of 57 field-caught species of mimetic hover flies (Diptera: Syrphidae) and quantifying their morphological similarity to a range of potential hymenopteran models. A purpose-built phylogeny for the hover flies was used to control for potential lack of independence due to shared evolutionary history. Those hover fly species that engage in behavioral mimicry (mock stinging, leg waving, wing wagging) were all large wasp mimics within the genera Spilomyia and Temnostoma. While the behavioral mimics assayed were good morphological mimics, not all good mimics were behavioral mimics. Therefore, while the behaviors may have evolved to augment good morphological mimicry, they do not advantage all good mimics.

  7. Effect of Phytosterols on the Crystallization Behavior of Oil-in-Water Milk Fat Emulsions.

    Science.gov (United States)

    Zychowski, Lisa M; Logan, Amy; Augustin, Mary Ann; Kelly, Alan L; Zabara, Alexandru; O'Mahony, James A; Conn, Charlotte E; Auty, Mark A E

    2016-08-31

    Milk has been used commercially as a carrier for phytosterols, but there is limited knowledge on the effect of added plant sterols on the properties of the system. In this study, phytosterols dispersed in milk fat at a level of 0.3 or 0.6% were homogenized with an aqueous dispersion of whey protein isolate (WPI). The particle size, morphology, ζ-potential, and stability of the emulsions were investigated. Emulsion crystallization properties were examined through the use of differential scanning calorimetry (DSC) and Synchrotron X-ray scattering at both small and wide angles. Phytosterol enrichment influenced the particle size and physical appearance of the emulsion droplets, but did not affect the stability or charge of the dispersed particles. DSC data demonstrated that, at the higher level of phytosterol addition, crystallization of milk fat was delayed, whereas, at the lower level, phytosterol enrichment induced nucleation and emulsion crystallization. These differences were attributed to the formation of separate phytosterol crystals within the emulsions at the high phytosterol concentration, as characterized by Synchrotron X-ray measurements. X-ray scattering patterns demonstrated the ability of the phytosterol to integrate within the milk fat triacylglycerol matrix, with a concomitant increase in longitudinal packing and system disorder. Understanding the consequences of adding phytosterols, on the physical and crystalline behavior of emulsions may enable the functional food industry to design more physically and chemically stable products. PMID:27476512

  8. Effect of Phytosterols on the Crystallization Behavior of Oil-in-Water Milk Fat Emulsions.

    Science.gov (United States)

    Zychowski, Lisa M; Logan, Amy; Augustin, Mary Ann; Kelly, Alan L; Zabara, Alexandru; O'Mahony, James A; Conn, Charlotte E; Auty, Mark A E

    2016-08-31

    Milk has been used commercially as a carrier for phytosterols, but there is limited knowledge on the effect of added plant sterols on the properties of the system. In this study, phytosterols dispersed in milk fat at a level of 0.3 or 0.6% were homogenized with an aqueous dispersion of whey protein isolate (WPI). The particle size, morphology, ζ-potential, and stability of the emulsions were investigated. Emulsion crystallization properties were examined through the use of differential scanning calorimetry (DSC) and Synchrotron X-ray scattering at both small and wide angles. Phytosterol enrichment influenced the particle size and physical appearance of the emulsion droplets, but did not affect the stability or charge of the dispersed particles. DSC data demonstrated that, at the higher level of phytosterol addition, crystallization of milk fat was delayed, whereas, at the lower level, phytosterol enrichment induced nucleation and emulsion crystallization. These differences were attributed to the formation of separate phytosterol crystals within the emulsions at the high phytosterol concentration, as characterized by Synchrotron X-ray measurements. X-ray scattering patterns demonstrated the ability of the phytosterol to integrate within the milk fat triacylglycerol matrix, with a concomitant increase in longitudinal packing and system disorder. Understanding the consequences of adding phytosterols, on the physical and crystalline behavior of emulsions may enable the functional food industry to design more physically and chemically stable products.

  9. Optical and morphological characteristics of zinc selenide-zinc sulfide solid solution crystals

    Science.gov (United States)

    Singh, N. B.; Su, Ching-Hua; Arnold, Bradley; Choa, Fow-Sen

    2016-10-01

    Experiments were performed to study the effect of point defects on the optical and morphological characteristics of zinc selenide-zinc sulfide ZnSe-ZnS (ZnSexS(1-x)) solid solution crystals grown under terrestrial (1-g) condition. We used the composition ZnSe0.91S0.09 and ZnSe0.73S0.27 for the detailed studies. Crystals of 8 mm and 12 mm diameter were grown using physical vapor transport methods. These crystals did not exhibit gross defects such as voids, bubbles or precipitates. The photoluminescence spectra indicated strong red emission for the 610-630-nm wavelength region in both crystals. This emission could be explained on the basis of high energy irradiation of Zn selenide. For the ZnSe0.73S0.27 crystal, absorption starts at a lower wavelength range (300 nm) when compared to the ZnSe0.91S0.09 crystal presumably due to the much higher bandgap of ZnS than that of ZnSe. Sharp peaks at 451 and 455 nm were observed for both samples corresponding to the band edge transitions, followed by a strong peak at 632 nm. These results were consistent with the observations based on Raman spectroscopy studies. Under 532-nm laser illumination both transverse optical (TO) and longitudinal optical (LO) phonon peaks appeared at Raman shifts of 220 and 280 Δcm-1, respectively. These peaks are similar to those observed for pure ZnSe Raman spectra for which TO and LO occur at 200 and 250 Δcm-1 for the x-axis (first order) polarization.

  10. Effects of Solvent and Impurities on Crystal Morphology of Zinc Lactate Trihydrate

    Institute of Scientific and Technical Information of China (English)

    杨芗钰; 钱刚; 张相洋; 段学志; 周兴贵

    2014-01-01

    The crystal morphology of zinc lactate trihydrate in the absence or presence of impurities (viz. succinic acid, L-malic acid and D-malic acid) is investigated by molecular simulation based on surface docking model and COMPASS force field. Combing simulation results with our previous experimental results, it is found that the solvent mainly has an inhibition effect on the (0 0 2) surface, and succinic acid impurity will inhibit the growth of (0 0 2) and (0 1 1) surfaces while two enantiomers of malic acid impurity will inhibit the (0 0 2) and (1 0 0) surfaces, which are in good agreement with the experimental results.

  11. Polymorphic behavior of isonicotinamide in cooling crystallization from various solvents

    Science.gov (United States)

    Hansen, Thomas B.; Taris, Alessandra; Rong, Ben-Guang; Grosso, Massimiliano; Qu, Haiyan

    2016-09-01

    In this work the nucleation of different polymorphs of isonicotinamide (INA) from different solvents has been studied. The metastable zone width of INA in cooling crystallization from five different solvents has been investigated and attempts have been made to reveal the link between the INA molecular self-association to the polymorphism of the nucleated crystals using ATR FT-IR (Attenuated Total Reflectance Fourier Transform Infrared) and Raman spectroscopy. Raman and IR spectra of INA dissolved in different solvents have demonstrated that the INA molecules might associate in different configurations, whereas, the link between the structure of the molecular self-association and the structure of the nucleated polymorph is complicated by the influence of INA concentration. This is consistent with our previous study with piroxicam. The cooling crystallization of INA from five different solvents resulted in two different polymorphs depending on the initial concentration of the solution. The results obtained in the present work showed that information about self-association of an API (Active Pharmaceutical Ingredient) in a given solvent is not sufficient to predict the polymorphic behavior in all scenarios.

  12. Crystallization behavior during melt-processing of ceramic waste forms

    Science.gov (United States)

    Tumurugoti, Priyatham; Sundaram, S. K.; Misture, Scott T.; Marra, James C.; Amoroso, Jake

    2016-05-01

    Multiphase ceramic waste forms based on natural mineral analogs are of great interest for their high chemical durability, radiation resistance, and thermodynamic stability. Melt-processed ceramic waste forms that leverage existing melter technologies will broaden the available disposal options for high-level nuclear waste. This work reports on the crystallization behavior in selected melt-processed ceramics for waste immobilization. The phase assemblage and evolution of hollandite, zirconolite, pyrochlore, and perovskite type structures during melt processing were studied using thermal analysis, x-ray diffraction, and electron microscopy. Samples prepared by melting followed by annealing and quenching were analyzed to determine and measure the progression of the phase assemblage. Samples were melted at 1500 °C and heat-treated at crystallization temperatures of 1285 °C and 1325 °C corresponding to exothermic events identified from differential scanning calorimetry measurements. Results indicate that the selected multiphase composition partially melts at 1500 °C with hollandite coexisting as crystalline phase. Perovskite and zirconolite phases crystallized from the residual melt at temperatures below 1350 °C. Depending on their respective thermal histories, different quenched samples were found to have different phase assemblages including phases such as perovskite, zirconolite and TiO2.

  13. Physiochemical Characterization of Iodine (V Oxide Part II: Morphology and Crystal Structure of Particulate Films

    Directory of Open Access Journals (Sweden)

    Brian K. Little

    2015-11-01

    Full Text Available In this study, the production of particulate films of iodine (V oxides is investigated. The influence that sonication and solvation of suspended particles in various alcohol/ketone/ester solvents have on the physical structure of spin or drop cast films is examined in detail with electron microscopy, powder x-ray diffraction, and UV-visible absorption spectroscopy. Results indicate that sonicating iodine oxides in alcohol mixtures containing trace amounts of water decreases deposited particle sizes and produces a more uniform film morphology. UV-visible spectra of the pre-cast suspensions reveal that for some solvents, the iodine oxide oxidizes the solvent, producing I2 and lowering the pH of the suspension. Characterizing the crystals within the cast films reveal their composition to be primarily HI3O8, their orientations to exhibit a preferential orientation, and their growth to be primarily along the ac-plane of the crystal, enhanced at higher spin rates. Spin-coating at lower spin rates produces laminate-like particulate films versus higher density, one-piece films of stacked particles produced by drop casting. The particle morphology in these films consists of a combination of rods, plates, cubes, and rhombohedra structure.

  14. Morphological changes of gamma prime precipitates in nickel-base superalloy single crystals

    International Nuclear Information System (INIS)

    Changes in the morphology of the gamma prime precipitate were examined during tensile creep at temperatures between 927 and 1038 C in 001-oriented single crystals of a Ni-Al-Mo-Ta superalloy. In this alloy, which has a large negative misfit of -0.80%, the gamma prime particles link together during creep to form platelets, or rafts, which are aligned with their broad faces perpendicular to the applied tensile axis. The dimensions of the gamma and gamma prime phases were measured as directional coarsening developed in an attempt to trace the changing morphology under various stress levels. In addition, the effects of initial microstructure, as well as slight compositional variations, were related to raft development and creep properties. The results showed that directional coarsening of gamma prime began during primary creep, and under certain conditions, continued to develop after the onset of steady-state creep. The length of the rafts increased linearly with time up to a plateau region. The thickness of the rafts, however, remained equal to the initial gamma prime size at least up through the onset of tertiary creep this is a clear indication of the stability of the finely-spaced gamma-gamma prime lamellar structure. It was found that the single crystals with the finest gamma prime size exhibited the longest creep lives, because the resultant rafted structure had a larger number of gamma-gamma prime interfaces per unit volume of material

  15. SYNTHESIS AND CRYSTALLIZATION BEHAVIOR OF POLY(ETHER ETHER KETONE ETHER KETONE) (PEEKEK)

    Institute of Scientific and Technical Information of China (English)

    Zhao-bin Qiu; Zhi-shen Mo; Ying-ning Yu; Hong-fang Zhang; Xian-hong Wang

    2000-01-01

    In this paper, the synthesis and crystallization behavior of poly(ether ether ketone ether ketone) (PEEKEK) are reported. PEEKEK was prepared from 4,4'-bis(p-fluorobenzoyl) diphenyl ether (4,4'-FBDE) and hydroquinone along the nucleophilic substitution route. The thermal properties were investigated by using DSC and TGA. The crystallization behavior of PEEKEK under several conditions, i.e., crystallization from the molten state (melt crystallization), crystallization from a quenched sample (cold crystallization) and crystallization induced by exposing glassy sample to methylene chloride (solvent-induced crystallization) has also been investigated. The results show that crystallization of PEEKEK could be induced by the above methods, and no polymorphism was found. The differences in the crystallization of PEEKEK induced by the above methods are seen in their degree of crystallinity.

  16. EM study of latent track morphology in TiO2 single crystals

    Science.gov (United States)

    O'Connell, J. H.; Skuratov, V. A.; Akilbekov, A.; Zhumazhanova, A.; Janse van Vuuren, A.

    2016-07-01

    A TEM investigation was conducted into the morphology of 167 MeV Xe (2 × 1010 cm-2 to 1014 cm-2) and 1 GeV Bi ion (2 × 1010 cm-2) induced latent tracks in single crystal TiO2 (rutile). At fluences up to 1011 cm-2 latent tracks are visible as discontinuous lines of strained crystal along the ion trajectory. From the implanted surface down to about 60-70 nm below the surface the tracks appear as continuous conical structures with a base of diameter 5-6 nm (Xe) and 8-9 nm (Bi) in contact with the surface with a mushroom shaped hillock extending outward from the surface. At fluences between 6 × 1012 cm-2 and 1013 cm-2 the crystal is amorphized but rod-like crystalline regions remain which are oriented along the ion trajectories. Amorphization extends from the surface down to 8.3 μm below suggesting an upper limit for the threshold electronic stopping power for amorphization of 7.3 keV nm-1. At 1014 cm-2 Xe the entire 8.3 μm subsurface region is rendered amorphous although some evidence of short range ordering remains.

  17. The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases

    Energy Technology Data Exchange (ETDEWEB)

    Stipanovic, Arthur J [SUNY College of Environmental Science and Forestry

    2014-11-17

    Consistent with the US-DOE and USDA “Roadmap” objective of producing ethanol and chemicals from cellulosic feedstocks more efficiently, a three year research project entitled “The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases” was initiated in early 2003 under DOE sponsorship (Project Number DE-FG02-02ER15356). A three year continuation was awarded in June 2005 for the period September 15, 2005 through September 14, 2008. The original goal of this project was to determine the effect of cellulose crystal structure, including allomorphic crystalline form (Cellulose I, II, III, IV and sub-allomorphs), relative degree of crystallinity and crystallite size, on the activity of different types of genetically engineered cellulase enzymes to provide insight into the mechanism and kinetics of cellulose digestion by “pure” enzymes rather than complex mixtures. We expected that such information would ultimately help enhance the accessibility of cellulose to enzymatic conversion processes thereby creating a more cost-effective commercial process yielding sugars for fermentation into ethanol and other chemical products. Perhaps the most significant finding of the initial project phase was that conversion of native bacterial cellulose (Cellulose I; BC-I) to the Cellulose II (BC-II) crystal form by aqueous NaOH “pretreatment” provided an increase in cellulase conversion rate approaching 2-4 fold depending on enzyme concentration and temperature, even when initial % crystallinity values were similar for both allomorphs.

  18. Cellulose nanowhiskers from coconut husk fibers: effect of preparation conditions on their thermal and morphological behavior

    Science.gov (United States)

    Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis from coconut husk fibers which had previously been submitted to a delignification process. The effects of preparation conditions on the thermal and morphological behavior of the nanocrystals were investigated. Cellulose nanowhisker sus...

  19. Superhydrophilic and Wetting Behavior of TiO2 Films and their Surface Morphologies

    International Nuclear Information System (INIS)

    TiO2 films, showing superhydrophilic behavior, are prepared by electron beam evaporation. Atomic force microscopy and the contact angle measurement were performed to characterize the morphology and wetting behavior of the TiO2 films. Most studies attribute the wetting behavior of TiO2 surfaces to their physical characteristics rather than surface chemistry. These physical characteristics include surface morphology, roughness, and agglomerate size. We arrange these parameters in order of effectiveness. Surface morphologies are demonstrated to be the most important. TiO2 films with particular morphologies show superhydrophilic behavior without external stimuli, and these thin films also show stable anti-contamination properties during cyclical wetting and drying. (cross-disciplinary physics and related areas of science and technology)

  20. Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bin [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Ecole Normale Supérieure, CNRS-ENS-UPMC UMR 8640, 24 Rue Lhomond, Paris 75005 (France); Chen, Zhengfang [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Kang, Jian, E-mail: jiankang@scu.edu.cn [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Yang, Feng; Chen, Jinyao; Cao, Ya; Xiang, Ming [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China)

    2015-03-20

    Highlights: • We prepared β-PPR and studied its crystallization behavior with different melt structures. • We observed surprising synergetic effect between β-NA and the ordered structures. • We explored the nature of ordered structures by calculating the equilibrium temperature. - Abstract: Polypropylene random copolymer (PPR) is one of important polypropylene types for the application fields. However, due to the random copolymer chain configuration, it is difficult to obtain high proportion of β-phase even under the influence of β-nucleating agent (β-NA). In this study, the melt structure (namely, the content of ordered structures in the melt) of β-nucleated ethylene-copolymerized PPR (β-PPR) was controlled by tuning the fusion temperature (T{sub f}), and its impact on the crystallization and polymorphic behavior of β-PPR was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized optical microscopy (PLM) and scanning electronic microscopy (SEM). The result revealed that compared with the β-nucleated iPP homo-polymer, it is more difficult for β-PPR to form β-crystals; interestingly, when T{sub f} is in the temperature range of 162–173 °C, the ordered structures survived in melt exhibit high β-nucleation efficiency under the influence of β-NA, resulting in significant increase of β-phase proportion and evident variation of crystalline morphology, which is called the Ordered Structure Effect (OSE). Moreover, through investigating the self-nucleation behavior and equilibrium melting temperature of pure PPR (non-nucleated PPR), the physical nature of the lower and upper limiting T{sub f} temperatures for the occurrence of OSE in β-PPR was explored; the role of ethylene co-monomer in the occurrence of OSE was discussed.

  1. Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

    International Nuclear Information System (INIS)

    Highlights: • We prepared β-PPR and studied its crystallization behavior with different melt structures. • We observed surprising synergetic effect between β-NA and the ordered structures. • We explored the nature of ordered structures by calculating the equilibrium temperature. - Abstract: Polypropylene random copolymer (PPR) is one of important polypropylene types for the application fields. However, due to the random copolymer chain configuration, it is difficult to obtain high proportion of β-phase even under the influence of β-nucleating agent (β-NA). In this study, the melt structure (namely, the content of ordered structures in the melt) of β-nucleated ethylene-copolymerized PPR (β-PPR) was controlled by tuning the fusion temperature (Tf), and its impact on the crystallization and polymorphic behavior of β-PPR was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized optical microscopy (PLM) and scanning electronic microscopy (SEM). The result revealed that compared with the β-nucleated iPP homo-polymer, it is more difficult for β-PPR to form β-crystals; interestingly, when Tf is in the temperature range of 162–173 °C, the ordered structures survived in melt exhibit high β-nucleation efficiency under the influence of β-NA, resulting in significant increase of β-phase proportion and evident variation of crystalline morphology, which is called the Ordered Structure Effect (OSE). Moreover, through investigating the self-nucleation behavior and equilibrium melting temperature of pure PPR (non-nucleated PPR), the physical nature of the lower and upper limiting Tf temperatures for the occurrence of OSE in β-PPR was explored; the role of ethylene co-monomer in the occurrence of OSE was discussed

  2. Oxygen Barrier Properties and Melt Crystallization Behavior of Poly(ethylene terephthalate/Graphene Oxide Nanocomposites

    Directory of Open Access Journals (Sweden)

    Anna Szymczyk

    2015-01-01

    Full Text Available Poly(ethylene terephthalate nanocomposites with low loading (0.1–0.5 wt% of graphene oxide (GO have been prepared by using in situ polymerization method. TEM study of nanocomposites morphology has shown uniform distribution of highly exfoliated graphene oxide nanoplatelets in PET matrix. Investigations of oxygen permeability of amorphous films of nanocomposites showed that the nanocomposites had better oxygen barrier properties than the neat PET. The improvement of oxygen permeability for PET nanocomposite films over the neat PET is approximately factors of 2–3.3. DSC study on the nonisothermal crystallization behaviors proves that GO acts as a nucleating agent to accelerate the crystallization of PET matrix. The evolution of the lamellar nanostructure of nanocomposite and neat PET was monitored by SAXS during nonisothermal crystallization from the melt. It was found that unfilled PET and nanocomposite with the highest concentration of GO (0.5 wt% showed almost similar values of the long period (L=11.4 nm for neat PET and L=11.5 nm for PET/0.5GO.

  3. Crystallization behavior of MgB{sub 2} films fabricated on copper cathodes via electrochemical technique

    Energy Technology Data Exchange (ETDEWEB)

    Yang Huazhe, E-mail: hzyang@mail.cmu.edu.cn [Department of Biophysics, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110001 (China); Sun Xiaguang; Yu Xiaoming [Institute of Materials Physics and Chemistry, School of Sciences, Northeastern University, Shenyang 110819 (China); Qi Yang, E-mail: qiyang@imp.neu.edu.cn [Institute of Materials Physics and Chemistry, School of Sciences, Northeastern University, Shenyang 110819 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer A modified electrolysis cell was devised to prepare MgB{sub 2} films on copper cathode. Black-Right-Pointing-Pointer Crystallization behavior of MgB{sub 2} phase of films was investigated. Black-Right-Pointing-Pointer Phase transformation of Mg-B and Mg-Cu compound was discussed. Black-Right-Pointing-Pointer Mechanism for the dendritic growth of MgB{sub 2} phase was proposed. - Abstract: An electrochemical technique was devised and settled to prepare MgB{sub 2} films on copper cathodes in MgCl{sub 2}-Mg(BO{sub 2}){sub 2}-NaCl-KCl molten salts. X-ray diffraction and scanning probe microscopy were adopted to investigate the phase composition and elements distribution of sample. R-T curve of film was monitored through standard four-probe method. Transmission electron microscope and scanning electron microscope analysis were chosen to investigate the crystallization behavior and morphology of the films at different electrolytic temperatures. The results indicated that MgB{sub 2} films were successfully fabricated on the copper cathodes, and the optimal electrolytic temperature was 601 Degree-Sign C. It was presumed that the non-conducting MgO impurities hindered continuous growth of MgB{sub 2} grain, which may result in dendritic growth of MgB{sub 2} grain.

  4. Effects of spacer length and terminal group on the crystallization and morphology of biscarbamates: a longer spacer does not reduce the melting temperature.

    Science.gov (United States)

    Khan, Mostofa Kamal; Sundararajan, Pudupadi R

    2013-05-01

    The effects of alkyl side chain and spacer lengths and the type of terminal group on the morphology and crystallization of a homologous series of biscarbamates (model compounds for polyurethanes) were investigated. Biscarbamates were synthesized with alkyl side chains of various lengths ranging from C4 to C18 and an alkyl spacer group with 12 CH2 units (C12 spacer) between the two hydrogen bonding motifs. The crystallization and morphological features are compared with the previously studied biscarbamates with a C6 spacer. As a token example, we also studied a biscarbamate molecule in which the terminal methyl group was replaced by a phenyl group. We stress four important conclusions of the study: (1) A number of studies in the literature found that the longer alkyl spacers reduced the thermal transition temperatures of the molecules, and such behavior was attributed to an increase in the flexibility of the alkyl spacer. However, the results of the present study are to the contrary. With the biscarbamates studied here, the hydrogen-bonding groups on both sides of the C12 spacer act as "anchors", and the longer spacer does not reduce the melting temperatures compared with those with the C6 spacer. (2) The melt viscosity measurements show shear-thinning behavior, which has been mostly observed with polysaccharides and hydrogen-bonded polymers. (3) Avrami analysis shows a two-stage crystallization, which is not commonly observed in organic small molecule systems. (4) The phenyl end group does not add another self-assembly code in terms of π-stacking but acts as a defect. While formation of crystals was observed for biscarbamates with short alkyl side chains with a C6 spacer, an increase in spacer length to C12 induces spherulitic morphology. Although the overall sizes of the spherulites are the same for both spacers, the rate of spherulite growth was higher and the crystallization rate was lower with the C12 spacer compared with the C6 spacer. In contrast with the

  5. Molecular simulation of water behaviors on crystal faces of hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    PAN Haihua; TAO Jinhui; WU Tao; TANG Ruikang

    2007-01-01

    The water behavior on (001) and (100) crystal faces of hydroxyapatite (HAP) were studied using molecular dynamics (MD) simulations.The study showed that the water molecules between the HAP faces were under conditions of strong electrical field and high pressure,and hence formed 2-3 well-organized water layers on the crystal surfaces.These structured water layers had ice-like features.Compared with the crystallographic [100] direction of HAP,the polarity along the [001] direction was stronger,which resulted in more structured water layers on the surface.The interaction of water molecules with the calcium and phosphate sites at the HAP-water interface was also studied.The results indicated the multiple pathways of water adsorption onto the HAP surfaces.This study revealed the formation and the detailed structure of water layers on HAP surfaces and suggested that the interracial water played an important role in stabilizing the HAP particles in aqueous solutions.

  6. The influence of the rate of selenium crystallization from aqueous solutions on its morphology

    Directory of Open Access Journals (Sweden)

    Harañczyk I.

    2002-01-01

    Full Text Available Selenium crystallization process from aqueous solutions was investigated at constant temperature of 357 K. Two different reducers were used, namely dissolved NaHSO3 and gaseous SO2. Experiments were conducted for solutions with different initial selenium concentration and different pH. The degree of conversion was determined as a function of time from the weight of the sediment, and can be described by Avrami-type equation of the following form: - ln ( 1 - á = (6.95 . 10 -3 . t 1.52 valid at constant temperature of 357 K for NaHSO3 reducer, rate constant k = 6.95.10-3 min-1, and t in minutes. When the reduction was carried out in SO2 stream, the rate constant k was found to be strongly dependent on the flow rate. Possible mechanism of the reduction process and the influence of the rate of the reduction on the morphology of the product were suggested.

  7. Bioleaching of incineration fly ash by Aspergillus niger – precipitation of metallic salt crystals and morphological alteration of the fungus

    OpenAIRE

    Tong-Jiang Xu; Thulasya Ramanathan; Yen-Peng Ting

    2014-01-01

    This study examines the bioleaching of municipal solid waste incineration fly ash by Aspergillus niger, and its effect on the fungal morphology, the fate of the ash particles, and the precipitation of metallic salt crystals during bioleaching. The fungal morphology was significantly affected during one-step and two-step bioleaching; scanning electron microscopy revealed that bioleaching caused distortion of the fungal hyphae (with up to 10 μm hyphae diameter) and a swollen pellet structure. I...

  8. Laser patterning and morphology of two-dimensional planar ferroelastic rare-earth molybdate crystals on the glass surface

    International Nuclear Information System (INIS)

    Research highlights: → Two-dimensional planar ferroelastic β'-(Sm,Gd)2(MoO4)3 crystals are patterned on the glass surface by laser irradiations with a small pitch (0.7 μm) between laser irradiated parts. → A high orientation of crystals is confirmed from micro-Raman scattering spectrum and second harmonic intensity measurements, and the crystal growth direction is perpendicular to the laser scanning direction. → This study proposes the possibility of the control of crystal growth direction in laser-induced crystallization in glass. - Abstract: The laser-induced crystallization method is applied to pattern two-dimensional planar crystals consisting of ferroelastic β'-(Sm,Gd)2(MoO4)3 crystals (designated here as SGMO crystals) on the surface of Sm2O3-Gd2O3-MoO3-B2O3 glass. By scanning Yb:YVO4 fiber lasers (wavelength: 1080 nm) continuously with a small pitch (0.7 μm) between laser irradiated parts, planar SGMO crystals with periodic domain structures showing different refractive indices are patterned successfully, and a high orientation of SGMO crystals is confirmed from micro-Raman scattering spectrum and second harmonic intensity measurements. It is found that the crystal growth direction is perpendicular to the laser scanning direction. This relation, i.e., the perpendicular relation, is a different from the behavior in discrete crystal line patterning, where the crystal growth direction is consistent with the laser scanning direction. The present study proposes the possibility of the control of crystal growth direction in laser-induced crystallization in glasses.

  9. Crystallization behavior and spherulites morphology of stereocomplexed poly(lactic acid) s with different molecular weights%不同分子质量聚乳酸立体复合物的结晶性能及球晶形貌

    Institute of Scientific and Technical Information of China (English)

    戈欢; 朱志国; 王锐; 尹会会; 王睿; 张秀芹

    2016-01-01

    同等质量的L-乳酸( PLLA)和D-乳酸( PDLA)共混后,能够形成立体复合聚乳酸( PLA).研究了5种不同相对分子质量(0.6×104~1.2×105)的PLLA和PDLA共混物的热性能、结晶动力学以及球晶的形态结构.聚合物均是通过L-LA或D-LA熔融固相聚合相结合的方法获得.与相应的均聚物比较,PLLA和PDLA溶液共混后形成的立体复合PLA具有更好的结晶性能和更高的熔点.分别以5、10、20、30℃/min为降温速率进行结晶动力学研究,发现较高分子质量样品具有更好的结晶速率,可能是因为样品中分子链在结晶发生之前具有更快的链复合能力.最后,通过偏光显微镜成功地在较低分子质量sc-PLA球晶结构中观察到了可逆的裂纹现象,证明裂纹的出现与结晶过程中形成的晶体间内应力有关.%Stereocomplex poly(lactic acid) (sc-PLA) could form in the mixture of poly(L-lactide) (PLLA) and poly(D-lactiole) (PDLA) at a mass ratio of 1∶1. In this paper, the thermal properties, crystallization kinetics and spherulites morphologies of the mixtures with different molecular weights (0. 6 × 4 -1. 2 × 105, homopolymers) were studied. All the homopolymers were prepared from L-LA or D-LA by melt condensation. Compared to corresponding homopolymers, sc-PLA formed by solution blending of PLLA and PDLA show much better crystallinity and higher melt temperature. The crystallization kinetics of the mixtures were investigated by DSC cooling scan at the rates of 5, 10, 20, and 30 ℃/min. The results showed that the samples with higher molecular weight, possess faster rates of crystallization, which should be ascribed to the better ability of stereocomplexation between the enantiometric chain segments prior to occurrence of crystallization. Finally in the study, the spherulites morphologies of mixtures were investigated on polarizing microscope. Cracks formed in the samples with lower molecular weight. The temperature-dependant reversibility of

  10. Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

    International Nuclear Information System (INIS)

    Highlights: → The thermal behavior of 3Y-TZP precursor powders had been investigated. → The crystallization behavior of 3Y-TZP nanopowders had been investigated. → The activation energy for crystallization of tetragonal ZrO2 was obtained. → The growth morphology parameter n is approximated as 2.0. → The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO2 crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 ± 21.9 kJ mol-1, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO2 was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

  11. Synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanosized powders prepared using a simple co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Yu-Wei [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yang, Ko-Ho, E-mail: yangkoho@cc.kuas.edu.tw [Graduate Institute of Applied Science, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Department of Mold and Die Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Dental Materials Research Center, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Yeh, Sung-Wei [Metal Industries Research and Development Centre, 1001 Kaohsiung Highway, Kaohsiung 811, Taiwan (China); Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100, Shihchuan 1st Road, Kaohsiung 80728, Taiwan (China)

    2011-06-16

    Highlights: > The thermal behavior of 3Y-TZP precursor powders had been investigated. > The crystallization behavior of 3Y-TZP nanopowders had been investigated. > The activation energy for crystallization of tetragonal ZrO{sub 2} was obtained. > The growth morphology parameter n is approximated as 2.0. > The crystallites show a plate-like morphology. - Abstract: The synthesis and crystallization behavior of 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) nanopowders prepared using a simple co-precipitation process at 348 K and pH = 7 were investigated using differential scanning calorimetry/thermogravimetry (DSC/TG), an X-ray diffractometer (XRD), the Raman spectra, transmission electron microscopy (TEM), selected area electron diffraction (SAED), and an energy dispersive spectrometer (EDS). The activation energy of tetragonal ZrO{sub 2} crystallization from 3Y-TZP freeze-dried precursor powders using a non-isothermal method, namely, 169.2 {+-} 21.9 kJ mol{sup -1}, was obtained. The growth morphology parameter n was approximated as 2.0, which indicated that it had a plate-like morphology. The XRD, Raman spectra, and SAED patterns showed that the phase of the tetragonal ZrO{sub 2} was maintained at 1273 K. The crystallite size of 3Y-TZP freeze-dried precursor powders calcined at 1273 K for 5 min was 21.3 nm.

  12. On the morphology of SrCO3 crystals grown at the interface between two immiscible liquids

    Indian Academy of Sciences (India)

    Satyanarayana Reddy; Debabrata Rautaray; S R Sainkar; Murali Sastry

    2003-04-01

    In this paper we report on the growth of strontianite crystals at the interface between an aqueous solution of Sr2+ ions and organic solutions of chloroform and hexane containing fatty acid/fatty amine molecules by reaction with sodium carbonate. When fatty acid was used as an additive at the interface, the crystals grown were self-assembled needle shaped strontianite crystallites branching out from the seed crystal via secondary nucleation. Under identical conditions of supersaturation, the presence of fatty amine molecules at the liquid–liquid interface resulted in needle shaped strontianite crystals with spherical crystallites arranged around central needles. This clearly indicates that the functionality of the head group of the amphiphiles at the liquid–liquid interface affects the morphology of the strontium carbonate crystals formed. The use of interfacial effects such as dielectric discontinuity, polarity and finite solubility of the two solvents etc opens up exciting possibilities for tailoring the morphology of crystals at the liquid–liquid interface and is currently not possible in the more popular crystal growth with similar amphiphiles at the air–water interface.

  13. Effect of film thickness on morphological evolution in dewetting and crystallization of polystyrene/poly(ε-caprolactone) blend films.

    Science.gov (United States)

    Ma, Meng; He, Zhoukun; Yang, Jinghui; Chen, Feng; Wang, Ke; Zhang, Qin; Deng, Hua; Fu, Qiang

    2011-11-01

    In this Article, the morphological evolution in the blend thin film of polystyrene (PS)/poly(ε-caprolactone) (PCL) was investigated via mainly AFM. It was found that an enriched two-layer structure with PS at the upper layer and PCL at the bottom layer was formed during spinning coating. By changing the solution concentration, different kinds of crystal morphologies, such as finger-like, dendritic, and spherulitic-like, could be obtained at the bottom PCL layer. These different initial states led to the morphological evolution processes to be quite different from each other, so the phase separation, dewetting, and crystalline morphology of PS/PCL blend films as a function of time were studied. It was interesting to find that the morphological evolution of PS at the upper layer was largely dependent on the film thickness. For the ultrathin (15 nm) blend film, a liquid-solid/liquid-liquid dewetting-wetting process was observed, forming ribbons that rupture into discrete circular PS islands on voronoi finger-like PCL crystal. For the thick (30 nm) blend film, the liquid-liquid dewetting of the upper PS layer from the underlying adsorbed PCL layer was found, forming interconnected rim structures that rupture into discrete circular PS islands embedded in the single lamellar PCL dendritic crystal due to Rayleigh instability. For the thicker (60 nm) blend film, a two-step liquid-liquid dewetting process with regular holes decorated with dendritic PCL crystal at early annealing stage and small holes decorated with spherulite-like PCL crystal among the early dewetting holes at later annealing stage was observed. The mechanism of this unusual morphological evolution process was discussed on the basis of the entropy effect and annealing-induced phase separation. PMID:21936570

  14. Soot Aerosol Particles as Cloud Condensation Nuclei: from Ice Nucleation Activity to Ice Crystal Morphology

    Science.gov (United States)

    Pirim, Claire; Ikhenazene, Raouf; Ortega, Isamel Kenneth; Carpentier, Yvain; Focsa, Cristian; Chazallon, Bertrand; Ouf, François-Xavier

    2016-04-01

    Emissions of solid-state particles (soot) from engine exhausts due to incomplete fuel combustion is considered to influence ice and liquid water cloud droplet activation [1]. The activity of these aerosols would originate from their ability to be important centers of ice-particle nucleation, as they would promote ice formation above water homogeneous freezing point. Soot particles are reported to be generally worse ice nuclei than mineral dust because they activate nucleation at higher ice-supersaturations for deposition nucleation and at lower temperatures for immersion freezing than ratios usually expected for homogeneous nucleation [2]. In fact, there are still numerous opened questions as to whether and how soot's physico-chemical properties (structure, morphology and chemical composition) can influence their nucleation ability. Therefore, systematic investigations of soot aerosol nucleation activity via one specific nucleation mode, here deposition nucleation, combined with thorough structural and compositional analyzes are needed in order to establish any association between the particles' activity and their physico-chemical properties. In addition, since the morphology of the ice crystals can influence their radiative properties [3], we investigated their morphology as they grow over both soot and pristine substrates at different temperatures and humidity ratios. In the present work, Combustion Aerosol STandart soot samples were produced from propane using various experimental conditions. Their nucleation activity was studied in deposition mode (from water vapor), and monitored using a temperature-controlled reactor in which the sample's relative humidity is precisely measured with a cryo-hygrometer. Formation of water/ice onto the particles is followed both optically and spectroscopically, using a microscope coupled to a Raman spectrometer. Vibrational signatures of hydroxyls (O-H) emerge when the particle becomes hydrated and are used to characterize ice

  15. AFM observation of the surface morphology and impurity effects on orthorhombic hen egg-white lysozyme crystals

    Science.gov (United States)

    Matsuzuki, Y.; Kubota, T.; Liu, X. Y.; Ataka, M.; Takano, K. J.

    2002-07-01

    Cation-exchange high performance liquid chromatography at pH 6, developed originally to purify human lysozyme, was applied to hen egg-white lysozyme. We could remove at least three kinds of impurities from the commercial product. The impurities were considered to be modified lysozyme molecules, mostly based on N-terminal amino acid analyses. Atomic force microscopic observation was made on the crystals both from the purified and non-purified solutions. The (1 1 0) faces of the orthorhombic crystals grown at 40°C from the purified solution contained linear steps, while most of the linear edges became round and rugged on the crystals from non-purified solutions. A similar change in step morphology is known to occur on insulin crystals when two amino acids were mutated from the wild type. On the (0 1 0) face, elongated, round steps became rugged when crystals grew from non-purified solutions.

  16. Crystallization Behavior and Heat Transfer of Fluorine-Free Mold Fluxes with Different Na2O Concentration

    Science.gov (United States)

    Yang, Jian; Zhang, Jianqiang; Sasaki, Yasushi; Ostrovski, Oleg; Zhang, Chen; Cai, Dexiang; Kashiwaya, Yoshiaki

    2016-08-01

    In this study, the crystallization behavior and heat transfer of CaO-SiO2-Na2O-B2O3-TiO2-Al2O3-MgO-Li2O fluorine-free mold fluxes with different Na2O contents (5 to 11 mass pct) were studied using single/double hot thermocouple technique (SHTT/DHTT) and infrared emitter technique (IET), respectively. Continuous cooling transformation (CCT) and time-temperature transformation (TTT) diagrams constructed using SHTT showed that crystallization temperature increased and incubation time shortened with the increase of Na2O concentration, indicating an enhanced crystallization tendency. The crystallization process of mold fluxes in the temperature field simulating the casting condition was also investigated using DHTT. X-ray diffraction (XRD) analysis of the quenched mold fluxes showed that the dominant phase changed from CaSiO3 to Ca11Si4B2O22 with the increasing concentration of Na2O. The heat transfer examined by IET showed that the increase of Na2O concentration reduced the responding heat flux when Na2O was lower than 9 mass pct but the further increase of Na2O to 11 mass pct enhanced the heat flux. The correlation between crystallinity and heat transfer was discussed in terms of crystallization tendency and crystal morphology.

  17. Photovoltaic properties and morphology of organic solar cells based on liquid-crystal semiconducting polymer with additive

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Zushi, Masahito; Suzuki, Hisato; Ogahara, Shinichi; Akiyama, Tsuyoshi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2014-02-20

    Bulk heterojunction organic solar cell based on liquid crystal semiconducting polymers of poly[9,9-dioctylfluorene-co-bithiophene] (F8T2) as p-type semiconductors and fullerenes (C{sub 60}) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as electron donor and acceptor has been fabricated and characterized for improving photovoltaic and optical properties. The photovoltaic performance including current voltage curves in the dark and illumination of the F8T2/C{sub 60} conventional and inverted bulk heterojunction solar cells were investigated. Relationship between the photovoltaic properties and morphological behavior was focused on tuning for optimization of photo-voltaic performance under annealing condition near glass transition temperature. Additive-effect of diiodooctane (DIO) and poly(3-hexylthiophene-2,5-diyl) (P3HT) on the photovoltaic performance and optical properties was investigated. Mechanism of the photovoltaic properties of the conventional and inverted solar cells will be discussed by the experimental results.

  18. Effects of reactor type and mass transfer on the morphology of CuS and ZnS crystals

    NARCIS (Netherlands)

    Al-Tarazi, M.; Heesink, A. Bert M.; Versteeg, G. F.

    2005-01-01

    For the precipitation of CuS and ZnS, the effects of the reactor/precipitator type, mass transfer and process conditions on crystal morphology were studied. Either H2S gas or a S2- solution were applied. Three different types of reactors have been tested, namely a laminar jet, a bubble column and an

  19. Effect of melt composition and crystal content on flow morphology along the Alarcón Rise, Mexico

    Science.gov (United States)

    Martin, J. F.; Lieberg-Clark, P.; Clague, D. A.; Caress, D. W.; Portner, R. A.; Paduan, J. B.; Dreyer, B. M.

    2012-12-01

    Differences in submarine lava flow morphology have been related to differences in eruption rate; low eruption rates form pillow-flow morphologies whereas high eruption rates form sheet-flow morphologies. Eruption rate is likely controlled by dike intrusion width, exsolved bubble content of the magma, viscosity of the magma, or some combination these three properties. Samples and observations from a 2012 expedition to the Alarcón Rise, Mexico, are used to evaluate the potential control of viscosity due to melt composition and crystal content on observed flow morphologies and associated eruption rates. A 1-m resolution multibeam survey, covering the entire 50 km length of the neovolcanic zone, was completed using the MBARI Mapping AUV. Based on the high-resolution bathymetry, two basic flow morphologies could be distinguished: pillow flows, comprising ~ 40 % of the rise, and sheet flows, comprising the remaining ~ 60 %. A series of dives using the ROVs Doc Ricketts in 2012 and Tiburon in 2003 visually confirmed pillow flows, lobate flows, sheet flows, and jumbled sheet flows at the sampled sites. Over 150 lava samples collected during the dives, spanning the entire length of the rise were analyzed for major-element chemistry, crystal content, and corresponding flow morphology. Lavas selected for this analysis ranged from basalt to basaltic-andesite (100 pa s, only pillow lavas are generated. The majority (> 80 %) of sampled pillow lavas are plagioclase-phyric to ultraphyric whereas the majority of lobate and sheet flow lavas are aphyric. Crystal fractions in the pillow lavas are as high as 30-40%, resulting in magma viscosities ~ 5-15 times the melt viscosities. The majority of pillow lavas (~77%) have magma viscosities > 100 pa s. Only ~ 25 % of lobate and sheet flow lavas have magma viscosities > 100 pa s. Many of the phyric lobate and sheet flow samples show evidence of strong flow segregation of crystals to the outer surface of the flow, resulting in samples

  20. Crystal growth of CdTe in space and thermal field effects on mass flux and morphology

    Science.gov (United States)

    Wiedemeier, H.

    1988-01-01

    The primary, long-range goals are the development of vapor phase crystal growth experiments, and the growth of technologically useful crystals in space. The necessary ground-based studies include measurements of the effects of temperature variations on the mass flux and crystal morphology in vapor-solid growth processes. For in-situ mass flux measurements dynamic microbalance techniques will be employed. Crystal growth procedures and equipment will be developed to be compatible with microgravity conditions and flight requirements. Emphasis was placed on the further development of crystal growth and the investigation of relevant transport properties of CdTe. The dependence of the mass flux on source temperature was experimentally established. The CdTe synthesis and pretreatment procedures are being developed that yield considerable improvements in mass transport rates, and mass fluxes which are independent of the amount of source material. A higher degree of stoichiometric control of CdTe than before was achieved during this period of investigation. Based on this, a CdTe crystal growth experiment, employing physical vapor transport, yielded very promising results. Optical microscopy and X-ray diffraction studies revealed that the boule contained several large sized crystal grains of a high degree of crystallinity. Further characterization studies of CdTe crystals are in progress. The reaction chamber, furnace dimensions, and ampoule location of the dynamic microbalance system were modified in order to minimize radiation effects on the balance performance.

  1. Crystallization behavior of plasma-sprayed lanthanide magnesium hexaaluminate coatings

    Institute of Scientific and Technical Information of China (English)

    Liang-liang Huang; Hui-min Meng; Jing Tang

    2014-01-01

    LaMgAl11O19 thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying. The crystallization behavior of the coatings and the synthesis mechanism of LaMgAl11O19 powders were researched. The results showed that the plasma-sprayed coatings con-tained some amorphous phase, and LaMgAl11O19 powders were partially decomposed into Al2O3, LaAlO3, and MgAl2O4 in the plasma spraying process. The amorphous phase was recrystallized at a temperature of approximately 1174.9°C, at which level the decomposed Al2O3, LaAlO3, and MgAl2O4 reacted again. The resynthesis temperature of LaMgAl11O19 in the plasma-sprayed coatings was lower than that of LaMgAl11O19 in the original raw powders. The synthesis mechanism of LaMgAl11O19 powders can be summarized as follows:during the first part of the overall reaction, La2O3 reacts with Al2O3 to form LaAlO3 at approximately 900°C, and then LaAlO3 further reacts with Al2O3 and MgAl2O4 to produce LaMgAl11O19 at approximately 1200°C.

  2. Behavioral mechanisms and morphological symptoms of zombie ants dying from fungal infection

    DEFF Research Database (Denmark)

    Hughes, David P; Andersen, Sandra B; Hywel-Jones, Nigel L;

    2011-01-01

    Parasites that manipulate host behavior can provide prominent examples of extended phenotypes: parasite genomes controlling host behavior. Here we focus on one of the most dramatic examples of behavioral manipulation, the death grip of ants infected by Ophiocordyceps fungi. We studied...... leaves ca. 25 cm above the soil surface where conditions for parasite development are optimal. Here we address whether the sequence of ant behaviors leading to the final death grip can also be interpreted as parasite adaptations and describe some of the morphological changes inside the heads of infected...

  3. EFFECTS OF BLENDING CHITOSAN WITH PEG ON SURFACE MORPHOLOGY,CRYSTALLIZATION AND THERMAL PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Ling-hao He; Rui Xue; De-bin Yang; Ying Liu; Rui Song

    2009-01-01

    Biodegradable blend films composed of chitosan and PEG with various composition ratios were prepared. The chemical structure of the blend films was characterized with FTIR and X-ray, which showed no chemical bond formations but certain interactions probably coming from the hydrogen bonds. Morphologies of these blend films were viewed using AFM and SEM, suggesting that pure chitosan film had a smooth surface structure and the blend films surface showed a plenty of holes with varying size. Through the DMA measurement, it was found that there existed differences in the peak area and position of the blend films, and the peak at the glass transition temperature became significantly weaker and was markedly wider with the increasing content of PEG. The obtained results showed that the crystallinity of chitosan was suppressed and partially destroyed; and this should have an influence on the thermal behaviors and dynamic mechanical properties of the blend films.

  4. L-{alpha} alanine crystals: theoretical and experimental morphology and habit modifications in CaCO{sub 3} solution

    Energy Technology Data Exchange (ETDEWEB)

    Massimino, F.; Bruno, M.; Rubbo, M.; Aquilano, D. [Dipartimento di Scienze Mineralogiche e Petrologiche, Universita di Torino, via Valperga Caluso 35, 10125 Torino (Italy)

    2011-08-15

    Empirical potential has been modified for {alpha}-alanine intermolecular interaction, in order to perform a Periodic Bond Chain (PBC) analysis. Equilibrium and growth shapes have been predicted in vacuum and the equilibrium shape has been successfully modified by the solvent interaction. {alpha}-alanine crystals have been prepared both in pure and in CaCO{sub 3} aqueous solution. Then, habit modification was observed and surface morphology analysis has been carried out on metallized crystals. Epitaxial model acting at the {alpha}-alanine/ CaCO{sub 3} interfaces is also proposed. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Surfactant Effects on the Morphology and Pseudocapacitive Behavior of V2 O5 ⋅H2 O.

    Science.gov (United States)

    Qian, Aniu; Zhuo, Kai; Shin, Myung Sik; Chun, Woo Won; Choi, Bit Na; Chung, Chan-Hwa

    2015-07-20

    To overcome the drawback of low electrical conductivity within supercapacitor applications, several surfactants are used for nanoscale V2 O5 to enhance the specific surface area. Polyethylene glycol 6000 (PEG-6000), sodium dodecylbenzene sulfonate (SDBS), and Pluronic P-123 (P123) controllers, if used as soft templates, easily form large specific surface area crystals. However, the specific mechanism through which this occurs and the influence of these surfactants is not clear for V2 O5 ⋅H2 O. In the present study, we aimed to investigate the mechanism of crystal growth through hydrothermal processes and the pseudocapacitive behavior of these crystals formed by using diverse surfactants, including PEG-6000, SDBS, and P123. Our results show that different surfactants can dramatically influence the morphology and capacitive behavior of V2 O5 ⋅H2 O powders. Linear nanowires, flower-like flakes, and curly bundled nanowires can be obtained because of electrostatic interactions in the presence of PEG-6000, SDBS, and P123, respectively. Furthermore, the electrochemical performance of these powders shows that the nanowires, which are electrodes mediated by PEG-6000, exhibit the highest capacitance of 349 F g(-1) at a scan rate of 5 mV s(-1) of all the surfactants studied. However, a symmetric P123 electrode comprising curly bundled nanowires with numerous nanopores showed an excellent and stable specific capacitance of 127 F g(-1) after 200 cycles. This work is beneficial to understanding the fundamental role of the surfactant in the assisted growth of V2 O5 ⋅H2 O and the resulting electrochemical properties of the pseudocapacitors, which could be useful for the future design of appropriate materials.

  6. Crystallization Behavior of Magnesium Salts:. a Summary of Some Experimental Observations

    Science.gov (United States)

    Xue, Dongfeng; Zou, Longjiang; Wang, Lei; Yan, Xiaoxing

    Some efficient methods have been developed to chemically prepare some magnesium salt products with multiscale morphologies such as MgCO3·3H2O and 5Mg(OH)2·MgSO4·2H2O whiskers, Mg5(CO3)4(OH)2·4H2O microplates and aggregates, and Mg(OH)2 plates and spheres. The crystallization processes of the as-prepared products were studied by designing different reaction routes and corresponding growth morphologies. In these solution chemical systems, Mg2+ cation was found to be easily coordinated by various ligands, and can be easily transformed into various compounds with variable compositions. The current crystallization observations of some magnesium salts can be readily simulated by the chemical bonding theory of single crystal growth. These results can guide the further studies of various magnesium salts with controllable morphologies.

  7. Frequency Behavior of a Quartz Crystal Microbalance (Qcm) in Contact with Selected Solutions

    OpenAIRE

    Z. A. Talib; Z. Baba; Kurosawa, S.; H. A.A. Sidek; A. Kassimb; W. M.M. Yunus

    2006-01-01

    A device was constructed to monitor viscosity of solutions using fundamental frequency of 9 MHz and 10 MHz quartz crystal. Piezoelectric quartz crystals with gold electrodes were mounted by O-ring in between liquid flow cell. Only one side of the crystal was exposed to the solutions which were pumped through silicon tube by a peristaltic pump. The measured frequency shift was observed in order to investigate the interfacial behavior of some selected solution in contact with one surface of Qua...

  8. Comparative locomotor behavior of chimpanzees and bonobos: the influence of morphology on locomotion.

    Science.gov (United States)

    Doran, D M

    1993-05-01

    Results from a 10 month study of adult male and female bonobos (Pan paniscus) in the Lomako Forest, Zaire, and those from a 7 month study of adult male and female chimpanzees in the Tai Forest, Ivory Coast (Pan troglodytes verus), were compared in order to determine whether there are species differences in locomotor behavior and substrate use and, if so, whether these differences support predictions made on the basis of interspecific morphological differences. Results indicate that bonobos are more arboreal than chimpanzees and that male bonobos are more suspensory than their chimpanzee counterpart. This would be predicted on the basis of male bonobo's longer and more narrow scapula. This particular finding is contrary to the prediction that the bonobo is a "scaled reduced version of a chimpanzee" with little or no positional behavior difference as had been suggested. This study provides the behavioral data necessary to untangle contradictory interpretations of the morphological differences between chimpanzees and bonobos, and raises a previously discussed (Fleagle: Size and Scaling in Primate Biology, pp. 1-19, 1985) but frequently overlooked point--that isometry in allometric studies does not necessarily equate with behavioral equivalence. Several researchers have demonstrated that bonobos and chimpanzees follow the same scaling trends for many features, and are in some sense functionally equivalent, since they manage to feed and reproduce. However, as reflected in their morphologies, they do so through different types and frequencies of locomotor behaviors. PMID:8512056

  9. Crystallization and melting behavior of multi-walled carbon nanotube-reinforced nylon-6 composites

    NARCIS (Netherlands)

    Phang, In Yee; Ma, Jianhua; Shen, Lu; Liu, Tianxi; Zhang, Wei-De

    2006-01-01

    The crystallization and melting behavior of neat nylon-6 (PA6) and multi-walled carbon nanotubes (MWNTs)/PA6 composites prepared by simple melt-compounding was comparatively studied. Differential scanning calorimetry (DSC) results show two crystallization exotherms (TCC, 1 and TCC, 2) for PA6/MWNTs

  10. Shear effects on crystallization behaviors and structure transitions of isotactic poly-1-butene

    DEFF Research Database (Denmark)

    Li, Jingqing; Guan, Peipei; Zhang, Yao;

    2014-01-01

    Different melt pre-shear conditions were applied to isotactic poly-1-butene (iP-1-B) and the effect on the crystallization behaviors and the crystalline structure transitions of iP-1-B were investigated. The polarized optical microscope observations during isothermal crystallization process revea...

  11. The effect of CaCO3 addition on the crystallization behavior of ZnO crystal glaze fired at different gloss firing and crystallization temperatures

    Directory of Open Access Journals (Sweden)

    Jamaludin A.R.

    2010-01-01

    Full Text Available A glazed ceramic product with crystalline structure gives an artistic effect. In this study, the effects of calcium carbonate (CaCO3 addition into glaze batches on the crystallization behavior of crystal glaze were studied. Samples were fired at different gloss firing temperatures ranging from 1000-1200°C with 1060°C crystallization temperature. Xray diffraction (XRD and energy dispersive X-ray spectrometer (EDX analysis of the phases identified these crystals as willemite (Zn2SiO4 in the form of spherulites. Scanning electron microscope (SEM analysis indicated that willemite crystals are in the acicular needle like shape. XRD result showed that the intensities of crystal peaks decreased with the addition of CaCO3 up to 3.0 wt%. However, there was no willemite crystals formation as the amount of CaCO3 raised to 5.0 wt%. Besides that, the results also indicated that willemite growth occurs during isothermal holding at crystallization temperature instead of during cooling from gloss firing temperature.

  12. Investigation of parameters affecting zeolite Na-A crystal size and morphology II - the effects of mixing rates, time and temperature on synthesis of zeolite A

    International Nuclear Information System (INIS)

    Morphology and crystal size of zeolites have an important role for their specific use in industries. Many parameters are found to be highly important in the physical appearance of the final zeolite products. In this work, some of the most effective parameters influencing the crystal size and morphology of zeolite A such as temperature and aging time of the gel preparation, crystallization temperature and rate of mixing during the synthesis were studied. Phase identification, morphology and the particle size of final products were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques

  13. Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

    Science.gov (United States)

    López-Fernández, Hernán; Arbour, Jessica; Willis, Stuart; Watkins, Crystal; Honeycutt, Rodney L; Winemiller, Kirk O

    2014-01-01

    Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny. PMID:24603485

  14. Phase separation of monomer in liquid crystal mixtures and surface morphology in polymer-stabilized vertical alignment liquid crystal displays

    Energy Technology Data Exchange (ETDEWEB)

    Lyu, Jae Jin; Lee, Jun Hyup; Kim, Kyeong Hyeon [Development Center, LCD Business, SAMSUNG Electronics Co. LTD., Tangjeong-Myeon, Asan, Chungnam 336-741 (Korea, Republic of); Kikuchi, Hirotsuku; Higuchi, Hiroki [Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga 816-8580 (Japan); Kim, Dae Hyun; Lee, Seung Hee, E-mail: jsquare.lyu@samsung.com, E-mail: lsh1@chonbuk.ac.kr [Department of BIN Fusion Technology and Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2011-08-17

    The polymer-stabilized vertically aligned (PS-VA) liquid crystal display (LCD) driving mode has high potential for manufacturing low power consuming displays due to the higher transmittance and fast response as compared with the existing patterned vertically aligned and multi-domain vertically aligned modes. In this paper we have investigated the reaction mechanisms of monomer-liquid crystal blends to form a surface pre-tilt angle of liquid crystal in vertical alignment LCD associated with a fishbone electrode structure. The observed sizes of polymer bumps formed on the substrates were found to be dependent on the exposed UV wavelength and were almost equal in both top and bottom substrates. When a large UV wavelength was used, the phase separation mechanism of monomer in PS-VA mode was found nearly isotropic rather than anisotropic in contrast to the previous studies.

  15. Effects of Mircostructure and Crystallographic Orientation on the Deformation Behavior of Ni/Ni{sub 3}Al Single Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Song, Seong Hun; Wee, Dang Moon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kishida, Kyosuke [Kyoto Univ., Kyoto (Japan); Demura, Masahiko; Hirano, Toshiyuki [National Institute for Materials Science, Ibaraki (Japan); Kim, Min Chul [KAERI, Daejeon (Korea, Republic of); Oh, Myung Hoon [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

    2007-02-15

    In order to study the deformation behavior depending on the initial crystallographic orientations and the morphology of Ni{sub 3}Al precipitates, the plane strain compression tests were carried out on the single crystals of Ni/Ni{sub 3}Al (Ni-18at.%Al) two-phase alloys. Flow behaviors were strongly dependent on the initial crystallographic orientations in DS18-3 alloys with rods and plates of Ni{sub 3}Al precipitates rather than DS18-1 alloys with Ni{sub 3}Al cuboids. For all orientations of DS18-1 alloys, and (110)[001]- and (110)[112]-oriented specimens of DS18-3 alloys, the flow behavior was thought to have a similar tendency at least up to strain level in this study, whereas the flow stresses were much lower for (100)[011]-, (100)[012]- and (210)[001]- oriented specimens in DS18-3 alloys. Such flow behavior is considered to be closely related to morphology of Ni3Al precipitates and cross-slip within Ni matrix which was related to the operative slip systems.

  16. Vapor diffusion method: Dependence of polymorphs and morphologies of calcium carbonate crystals on the depth of an aqueous solution

    Science.gov (United States)

    Liu, Qing; Wang, Hai-Shui; Zeng, Qiang

    2016-09-01

    The polymorph control of calcium carbonate by the vapor diffusion method is still a challenging issue because the resultant crystal polymorphs and morphologies highly depend on the experimental setup. In this communication, we demonstrated that the concentration gradients accompanied by the vapor diffusion method (ammonia concentration, pH and the ratio of CO32- to Ca2+ are changed with the solution depth and with time) are probably the main reasons to significantly affect the formation of crystal polymorphs. Raman, SEM and XRD data showed that calcite and vaterite crystals were preferred to nucleate and grow in the upper or the lower areas of aqueous solution respectively. The above results can be explained by the gradient effect.

  17. Crystallization behavior of vapor-deposited hexanitroazobenzene (HNAB) films

    Science.gov (United States)

    Knepper, Robert; Tappan, Alexander S.; Rodriguez, Mark A.; Alam, M. Kathleen; Martin, Laura; Marquez, Michael P.

    2012-03-01

    Vapor-deposited hexanitroazobenzene (HNAB) has been shown to form an amorphous structure as-deposited that crystallizes over a period ranging from several hours to several weeks, depending on the ambient temperature. Raman spectroscopy and x-ray diffraction were used to identify three distinct phases during the crystallization process: the as-deposited amorphous structure, the HNAB-II crystal structure, and an as-yet unidentified crystal structure. Significant qualitative differences in the nucleation and growth of the crystalline phases were observed between 65°C and 75°C. While the same two polymorphs form in all cases, significant variation in the quantities of each phase was observed as a function of temperature.

  18. Crystallization behavior of tetragonal ZrO{sub 2} prepared in a silica bath

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Huang, Hung-Jui [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China)

    2013-09-10

    Highlights: ► The activation energy of t-ZrO{sub 2} crystallization calculated by the JMA equation is 643.0 ± 13.9 kJ·mol{sup −1}. ► The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0. ► Bulk nucleation is dominant in the t-ZrO{sub 2} crystallization process, and has a spherical-like morphology. ► The TEM microstructure reveals that the t-ZrO{sub 2} crystallites have a spherical-like morphology. - Abstract: The synthesis of zirconia (ZrO{sub 2}) precursor powders by a co-precipitation process is studied in this work, using a silica bath prepared at 348 K and pH = 7, with 10 min mixing using zirconium (IV) nitrate and tetraethylorthosilicate (TEOS, Si(OC{sub 2}H{sub 5}){sub 4}) as the starting materials. The XRD result show that only a single phase of tetragonal ZrO{sub 2} (t-ZrO{sub 2}) appears when the freeze dried precursor powders are calcined between 1173 and 1473 K for 120 min. The activation energy of t-ZrO{sub 2} crystallization, as calculated by the Johnson–Mehl–Avrami (JMA) equation, is 643.0 ± 13.9 kJ/mol. The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0, which indicates that bulk nucleation is dominant in the t-ZrO{sub 2} crystallization process, and that the material has a plate-like morphology.

  19. Crystallization behavior of tetragonal ZrO2 prepared in a silica bath

    International Nuclear Information System (INIS)

    Highlights: ► The activation energy of t-ZrO2 crystallization calculated by the JMA equation is 643.0 ± 13.9 kJ·mol−1. ► The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0. ► Bulk nucleation is dominant in the t-ZrO2 crystallization process, and has a spherical-like morphology. ► The TEM microstructure reveals that the t-ZrO2 crystallites have a spherical-like morphology. - Abstract: The synthesis of zirconia (ZrO2) precursor powders by a co-precipitation process is studied in this work, using a silica bath prepared at 348 K and pH = 7, with 10 min mixing using zirconium (IV) nitrate and tetraethylorthosilicate (TEOS, Si(OC2H5)4) as the starting materials. The XRD result show that only a single phase of tetragonal ZrO2 (t-ZrO2) appears when the freeze dried precursor powders are calcined between 1173 and 1473 K for 120 min. The activation energy of t-ZrO2 crystallization, as calculated by the Johnson–Mehl–Avrami (JMA) equation, is 643.0 ± 13.9 kJ/mol. The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0, which indicates that bulk nucleation is dominant in the t-ZrO2 crystallization process, and that the material has a plate-like morphology

  20. STUDIES ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIOR OF POLYETHYLENE COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    ZHU Jin; OU Yuchun; FENG Yupeng

    1995-01-01

    The effects of interfacial modifier on the mechanical, dynamic mechanical properties and crystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersed phase of the composites, resulting in different phase structure, which was the major reason leading to different mechanical and crystallization properties.

  1. Quartic coupling and its effect on wetting behaviors in nematic liquid crystals

    Institute of Scientific and Technical Information of China (English)

    曾明颖; Holger Merlitz; 吴晨旭

    2015-01-01

    Based on the fact that patterns of rubbed groove also affect anchoring of liquid crystals at substrates, a quartic coupling is included in constructing the surface energy for a liquid crystal cell. The phase diagram and the wetting behaviors of liquid crystal cell, bounded by surfactant-laden interfaces in a magnetic field perpendicular to the substrate are discussed by taking the quartic coupling into account. The nematic order increases at the surface while decreases in the bulk as a result of the introduction of quartic substrate–liquid crystal coupling, indicating that the groove anchoring makes the liquid crystal molecules align more orderly near the substrate than away from it. This causes a different wetting behavior: complete wetting.

  2. Crystallization behavior of anhydrous milk fat-sunflower oil wax blends.

    Science.gov (United States)

    Kerr, Rebekah M; Tombokan, Xenia; Ghosh, Supriyo; Martini, Silvana

    2011-03-23

    This research evaluates the effect of sunflower oil wax (SFOw) addition on the crystallization behavior and functional properties of anhydrous milk fat (AMF). Induction times of nucleation, melting behavior, microstructure of crystals, and hardness were evaluated for samples of pure AMF and AMF with 0.1 and 0.25% SFOw. Results from this research show that the addition of waxes induced the onset of crystallization of AMF by inducing its nucleation, as evidenced by decreased induction times of nucleation and the formation of smaller crystals. Crystal growth after tempering was also promoted by waxes, and significantly harder lipid networks were obtained. Results presented in this paper suggest that SFOw can be used as an additive to alter the physiochemical properties of low trans-fatty acid lipids.

  3. Crystallization behavior of Fe78Si13B9 metallic glass under high magnetic field

    Institute of Scientific and Technical Information of China (English)

    Yuanfei Yu; Baozhu Liu; Min Qi

    2008-01-01

    The effects of high magnetic field on the crystallization behavior of the Fe78Si13B9 metallic glass ribbon were studied. The samples were isothermal annealed for 30 min under high magnetic field and no field, respectively. Mierostructure transformation during crystallization was identified by X-ray diffraction and transmission electron microscopy. It was found that the crystallizations of Fe78Si13B9 metallic glass processed under different conditions were that the precipitation of dendrite α-Fe(Si) and spherulite (Fe,Si)3B phases forms amorphous matrix and then the metastable (Fe, Si)3B phase transforms into the stable Fe2B phase. The grain size of the crystals is smaller and more homogeneous for the isothermal annealed samples under high magnetic field in comparison with that under no field indicating that the crystallization behavior of Fe78Si13B9 metallic glass is suppressed by high magnetic field.

  4. Crystal structure and electrochemical behaviors of Pt/mischmetal film electrodes

    Institute of Scientific and Technical Information of China (English)

    张文魁; 杨晓光; 马淳安; 王云刚; 余厉阳

    2003-01-01

    The Ml(La-rich mischmetal) films with a thin Pt layer on the substrate of chemically coarsen ITO glassor silicon slices were prepared by magnetic sputtering technique. The crystal structure and surface morphology ofthe films were investigated by X-ray diffraction(XRD) analysis and atomic force microscopy(AFM), respectively.The electrochemical hydridation/dehydridation behaviors of the films in KOH solution were studied by using cyclicvoltammagraph and electrochemical impedance spectrum(EIS) as well. The AFM results show that the Pt cover lay-er on the M1 films is of island structure with a grain of 150 - 200 nm in size. The presence of a thin Pt layer can pro-vide sufficient high electrocatalytic activity for the electrochemical charge-transfer reaction. The electrochemical re-duction and oxidation reaction occur on the Pt layer, and the diffusion of H into the Ml film is the rate-controlledstep. The Pt coatings also act as protective layers, preventing oxidation and/or poisoning of the underlying Ml filmsin air.

  5. Evolution of bower building in Lake Malawi cichlid fish: Phylogeny, morphology, and behavior

    Directory of Open Access Journals (Sweden)

    Ryan eYork

    2015-03-01

    Full Text Available Despite considerable research, we still know little about the proximate and ultimate causes behind behavioral evolution. This is partly because understanding the forces acting on behavioral phenotypes requires the study of species-rich clades with extensive variation in behavioral traits, of which we have few current examples. In this paper, we introduce the bower-building cichlids of the Lake Malawi adaptive radiation, a lineage with over 100 species, each possessing a distinct male extended phenotype used to signal reproductive fitness. Extended phenotypes are useful units of analysis for the study of behavior since they are static structures that can be precisely measured within populations. To this end we recognize two core types of bowers - mounds (castles and depressions (pits. We employ an established framework for the study of adaptive radiations to ask how traits related to other stages of radiations, macrohabitat and feeding morphology, are associated with the evolution of pit and castle phenotypes. We demonstrate that pits and castles are evolutionarily labile traits and have been derived numerous times in multiple Malawi genera. Using public ecological and phenotypic data sets we find significant and correlated differences in macrohabitat (depth, sensory ability (opsin expression, and feeding style (jaw morphology and biomechanics between pit-digging and castle-building species. Phylogeny-corrected comparisons also show significant differences in several measures of jaw morphology while indicating non-significant differences in depth. Finally, using laboratory observations we assay courtship behaviors in a pit-digging (Copadichromis virginalis and a castle-building species (Mchenga conophoros. Together, these results show that traits at multiple biological levels act to regulate the evolution of a courtship behavior within natural populations.

  6. A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior.

    Science.gov (United States)

    Martin, Adam D; Wojciechowski, Jonathan P; Bhadbhade, Mohan M; Thordarson, Pall

    2016-03-01

    Short peptides capped at their N-terminus are often highly efficient gelators, yet notoriously difficult to crystallize. This is due to strong unidirectional interactions within fibers, resulting in structure propagation only along one direction. Here, we synthesize the N-capped dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels and single crystals. Even more remarkably, we show using atomic force microscopy the coexistence of these two distinct phases. We then use powder X-ray diffraction to investigate whether the single crystal structure can be extrapolated to the molecular arrangement within the hydrogel. The results suggest parallel β-sheet arrangement as the dominant structural motif, challenging existing models for gelation of short peptides, and providing new directions for the future rational design of short peptide gelators. PMID:26890360

  7. Gender identification of Grasshopper Sparrows comparing behavioral, morphological, and molecular techniques

    Science.gov (United States)

    Ammer, F.K.; Wood, P.B.; McPherson, R.J.

    2008-01-01

    Correct gender identification in monomorphic species is often difficult especially if males and females do not display obvious behavioral and breeding differences. We compared gender specific morphology and behavior with recently developed DNA techniques for gender identification in the monomorphic Grasshopper Sparrow (Ammodramus savannarum). Gender was ascertained with DNA in 213 individuals using the 2550F/2718R primer set and 3% agarose gel electrophoresis. Field observations using behavior and breeding characteristics to identify gender matched DNA analyses with 100% accuracy for adult males and females. Gender was identified with DNA for all captured juveniles that did not display gender specific traits or behaviors in the field. The molecular techniques used offered a high level of accuracy and may be useful in studies of dispersal mechanisms and winter assemblage composition in monomorphic species.

  8. Handed foraging behavior in scale-eating cichlid fish: its potential role in shaping morphological asymmetry.

    Directory of Open Access Journals (Sweden)

    Hyuk Je Lee

    Full Text Available Scale-eating cichlid fish, Perissodus microlepis, from Lake Tanganyika display handed (lateralized foraging behavior, where an asymmetric 'left' mouth morph preferentially feeds on the scales of the right side of its victim fish and a 'right' morph bites the scales of the left side. This species has therefore become a textbook example of the astonishing degree of ecological specialization and negative frequency-dependent selection. We investigated the strength of handedness of foraging behavior as well as its interaction with morphological mouth laterality in P. microlepis. In wild-caught adult fish we found that mouth laterality is, as expected, a strong predictor of their preferred attack orientation. Also laboratory-reared juvenile fish exhibited a strong laterality in behavioral preference to feed on scales, even at an early age, although the initial level of mouth asymmetry appeared to be small. This suggests that pronounced mouth asymmetry is not a prerequisite for handed foraging behavior in juvenile scale-eating cichlid fish and might suggest that behavioral preference to attack a particular side of the prey plays a role in facilitating morphological asymmetry of this species.

  9. Sr-containing hydroxyapatite: morphologies of HA crystals and bioactivity on osteoblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Aina, Valentina [Department of Chemistry, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino (Italy); Centre of Excellence NIS (Nanostructured Interfaces and Surface) Università degli Studi di Torino (Italy); INSTM (Italian National Consortium for Materials Science and Technology), UdR Università di Torino (Italy); Bergandi, Loredana, E-mail: loredana.bergandi@unito.it [Department of Oncology, Università degli Studi di Torino, Via Santena 5/bis, 10126 Torino (Italy); Lusvardi, Gigliola; Malavasi, Gianluca [Department of Chemical and Geological Sciences, Università di Modena and Reggio Emilia, Via Campi 183, 41125 Modena (Italy); Imrie, Flora E.; Gibson, Iain R. [School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD (United Kingdom); Cerrato, Giuseppina [Department of Chemistry, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino (Italy); Centre of Excellence NIS (Nanostructured Interfaces and Surface) Università degli Studi di Torino (Italy); INSTM (Italian National Consortium for Materials Science and Technology), UdR Università di Torino (Italy); Ghigo, Dario [Department of Oncology, Università degli Studi di Torino, Via Santena 5/bis, 10126 Torino (Italy)

    2013-04-01

    A series of Sr-substituted hydroxyapatites (HA), of general formula Ca{sub (10−x)}Sr{sub x}(PO{sub 4}){sub 6}(OH){sub 2}, where x = 2 and 4, were synthesized by solid state methods and characterized extensively. The reactivity of these materials in cell culture medium was evaluated, and the behavior towards MG-63 osteoblast cells (in terms of cytotoxicity and proliferation assays) was studied. Future in vivo studies will give further insights into the behavior of the materials. A paper by Lagergren et al. (1975), concerning Sr-substituted HA prepared by a solid state method, reports that the presence of Sr in the apatite composition strongly influences the apatite diffraction patterns. Zeglinsky et al. (2012) investigated Sr-substituted HA by ab initio methods and Rietveld analyses and reported changes in the HA unit cell volume and shape due to the Sr addition. To further clarify the role played by the addition of Sr on the physico-chemical properties of these materials we prepared Sr-substituted HA compositions by a solid state method, using different reagents, thermal treatments and a multi-technique approach. Our results indicated that the introduction of Sr at the levels considered here does influence the structure of HA. There is also evidence of a decrease in the crystallinity degree of the materials upon Sr addition. The introduction of increasing amounts of Sr into the HA composition causes a decrease in the specific surface area and an enrichment of Sr-apatite phase at the surface of the samples. Bioactivity tests show that the presence of Sr causes changes in particle size and/or morphology during soaking in MEM solution; on the contrary the morphology of pure HA does not change after 14 days of reaction. The presence of Sr, as Sr-substituted HA and SrCl{sub 2,} in cultures of human MG-63 osteoblasts did not produce any cytotoxic effect. In fact, Sr-substituted HA increased the proliferation of osteoblast cells and enhanced cell differentiation: Sr in

  10. Preparation, morphologies and thermal behavior of high nitrogen compound 2-amino-4,6-diazido-s-triazine and its derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Qi-Long, E-mail: terry.well@163.com [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Musil, Tomáš [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Zeman, Svatopluk, E-mail: svatopluk.zeman@upce.cz [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Matyáš, Robert [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic); Shi, Xiao-Bing [Xi‘an Modern Chemistry Research Institute, 710065 Xi’an (China); Vlček, Milan [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 12006 Prague (Czech Republic); Pelikán, Vojtěch [Institute of Energetic Materials, Faculty of Chemical Technology, University of Pardubice, 53210 Pardubice (Czech Republic)

    2015-03-20

    Graphical abstract: High nitrogen compound 2-amino-4,6-diazido-s-triazine (DAAT) can be substituted by different function groups, forming many other new energetic materials. Such materials that have very close molecular structure may be very different in terms of crystal structure, thermal behavior, as well as performances (e.g., TAAT vs. TAHT). Generally, the increase of the molecular weight results in better thermal stability. - Highlights: • The crystal morphologies of azido-triazine derivatives are examined using SEM. • The thermal stability and decomposition processes are compared by TGA and DSC. • The effect of function group on the thermal behavior of title compounds is clarified. - Abstract: The crystal morphologies, thermal behavior, sensitivity and performance of 2-amino-4,6,-diazido-s-triazine and its derivatives have been investigated using SEM, DSC, TG techniques and related theories. It has been shown that the DANT crystal is in 1–5 μm thickness layered regular hexagon structure with severe agglomeration. DAAT crystal is very hydrophobic and can be dispersed in water, which has layered rectangle structure with thickness less than 0.5 μm. The TAHT materials exist in a form of amorphous irregular particles with diameters of more than 200 μm while its analogue TAAT can be crystallized in needle shape with a length of 30 μm. TNADAzT crystal has a shape of regular polyhedron with average size of about 120 μm. The thermal analysis indicates that there is only one complex step for decomposition of DAAT, while at least three steps are included for the other materials. DAAT started to decompose at around 148.4 °C with a peak temperature of 197.0 °C, while TAHT started to decompose at 167.2 °C with shoulder-peak of 193.4–206.7 °C at the heating rate of 2.0 °C min{sup −1}. DANT decomposes with a heat release of 2420–2721 J g{sup −1}, which is much higher than that of DAAT indicating that the heat and its release rate are greatly

  11. Preparation, morphologies and thermal behavior of high nitrogen compound 2-amino-4,6-diazido-s-triazine and its derivatives

    International Nuclear Information System (INIS)

    Graphical abstract: High nitrogen compound 2-amino-4,6-diazido-s-triazine (DAAT) can be substituted by different function groups, forming many other new energetic materials. Such materials that have very close molecular structure may be very different in terms of crystal structure, thermal behavior, as well as performances (e.g., TAAT vs. TAHT). Generally, the increase of the molecular weight results in better thermal stability. - Highlights: • The crystal morphologies of azido-triazine derivatives are examined using SEM. • The thermal stability and decomposition processes are compared by TGA and DSC. • The effect of function group on the thermal behavior of title compounds is clarified. - Abstract: The crystal morphologies, thermal behavior, sensitivity and performance of 2-amino-4,6,-diazido-s-triazine and its derivatives have been investigated using SEM, DSC, TG techniques and related theories. It has been shown that the DANT crystal is in 1–5 μm thickness layered regular hexagon structure with severe agglomeration. DAAT crystal is very hydrophobic and can be dispersed in water, which has layered rectangle structure with thickness less than 0.5 μm. The TAHT materials exist in a form of amorphous irregular particles with diameters of more than 200 μm while its analogue TAAT can be crystallized in needle shape with a length of 30 μm. TNADAzT crystal has a shape of regular polyhedron with average size of about 120 μm. The thermal analysis indicates that there is only one complex step for decomposition of DAAT, while at least three steps are included for the other materials. DAAT started to decompose at around 148.4 °C with a peak temperature of 197.0 °C, while TAHT started to decompose at 167.2 °C with shoulder-peak of 193.4–206.7 °C at the heating rate of 2.0 °C min−1. DANT decomposes with a heat release of 2420–2721 J g−1, which is much higher than that of DAAT indicating that the heat and its release rate are greatly enhanced by

  12. The impact of carbon on single crystal nickel-base superalloys: Carbide behavior and alloy performance

    Science.gov (United States)

    Wasson, Andrew Jay

    Advanced single crystal nickel-base superalloys are prone to the formation of casting grain defects, which hinders their practical implementation in large gas turbine components. Additions of carbon (C) have recently been identified as a means of reducing grain defects, but the full impact of C on single crystal superalloy behavior is not entirely understood. A study was conducted to determine the effects of C and other minor elemental additions on the behavior of CMSX-4, a commercially relevant 2nd generation single crystal superalloy. Baseline CMSX-4 and three alloy modifications (CMSX-4 + 0.05 wt. % C, CMSX-4 + 0.05 wt. % C and 68 ppm boron (B), and CMSX-4 + 0.05 wt. % C and 23 ppm nitrogen (N)) were heat treated before being tested in high temperature creep and high cycle fatigue (HCF). Select samples were subjected to long term thermal exposure (1000 °C/1000 hrs) to assess microstructural stability. The C modifications resulted in significant differences in microstructure and alloy performance as compared to the baseline. These variations were generally attributed to the behavior of carbide phases in the alloy modifications. The C modification and the C+B modification, which both exhibited script carbide networks, were 25% more effective than the C+N modification (small blocky carbides) and 10% more effective than the baseline at preventing grain defects in cast bars. All C-modified alloys exhibited reduced as-cast gamma/gamma' eutectic and increased casting porosity as compared to baseline CMSX-4. The higher levels of porosity (volume fractions 0.002 - 0.005 greater than the baseline) were attributed to carbides blocking molten fluid flow during the final stages of solidification. Although the minor additions resulted in reduced solidus temperature by up to 16 °C, all alloys were successfully heat treated without incipient melting by modifying commercial heat treatment schedules. In the B-containing alloy, heat treatment resulted in the transformation of

  13. Behavioral mechanisms and morphological symptoms of zombie ants dying from fungal infection

    Directory of Open Access Journals (Sweden)

    Himaman Winanda

    2011-05-01

    Full Text Available Abstract Background Parasites that manipulate host behavior can provide prominent examples of extended phenotypes: parasite genomes controlling host behavior. Here we focus on one of the most dramatic examples of behavioral manipulation, the death grip of ants infected by Ophiocordyceps fungi. We studied the interaction between O. unilateralis s.l. and its host ant Camponotus leonardi in a Thai rainforest, where infected ants descend from their canopy nests down to understory vegetation to bite into abaxial leaf veins before dying. Host mortality is concentrated in patches (graveyards where ants die on sapling leaves ca. 25 cm above the soil surface where conditions for parasite development are optimal. Here we address whether the sequence of ant behaviors leading to the final death grip can also be interpreted as parasite adaptations and describe some of the morphological changes inside the heads of infected workers that mediate the expression of the death grip phenotype. Results We found that infected ants behave as zombies and display predictable stereotypical behaviors of random rather than directional walking, and of repeated convulsions that make them fall down and thus precludes returning to the canopy. Transitions from erratic wandering to death grips on a leaf vein were abrupt and synchronized around solar noon. We show that the mandibles of ants penetrate deeply into vein tissue and that this is accompanied by extensive atrophy of the mandibular muscles. This lock-jaw means the ant will remain attached to the leaf after death. We further present histological data to show that a high density of single celled stages of the parasite within the head capsule of dying ants are likely to be responsible for this muscular atrophy. Conclusions Extended phenotypes in ants induced by fungal infections are a complex example of behavioral manipulation requiring coordinated changes of host behavior and morphology. Future work should address the

  14. Morphology and efficiency of a specialized foraging behavior, sediment sifting, in neotropical cichlid fishes.

    Directory of Open Access Journals (Sweden)

    Hernán López-Fernández

    Full Text Available Understanding of relationships between morphology and ecological performance can help to reveal how natural selection drives biological diversification. We investigate relationships between feeding behavior, foraging performance and morphology within a diverse group of teleost fishes, and examine the extent to which associations can be explained by evolutionary relatedness. Morphological adaptation associated with sediment sifting was examined using a phylogenetic linear discriminant analysis on a set of ecomorphological traits from 27 species of Neotropical cichlids. For most sifting taxa, feeding behavior could be effectively predicted by a linear discriminant function of ecomorphology across multiple clades of sediment sifters, and this pattern could not be explained by shared evolutionary history alone. Additionally, we tested foraging efficiency in seven Neotropical cichlid species, five of which are specialized benthic feeders with differing head morphology. Efficiency was evaluated based on the degree to which invertebrate prey could be retrieved at different depths of sediment. Feeding performance was compared both with respect to feeding mode and species using a phylogenetic ANCOVA, with substrate depth as a covariate. Benthic foraging performance was constant across sediment depths in non-sifters but declined with depth in sifters. The non-sifting Hypsophrys used sweeping motions of the body and fins to excavate large pits to uncover prey; this tactic was more efficient for consuming deeply buried invertebrates than observed among sediment sifters. Findings indicate that similar feeding performance among sediment-sifting cichlids extracting invertebrate prey from shallow sediment layers reflects constraints associated with functional morphology and, to a lesser extent, phylogeny.

  15. Influence of Molecular Interaction on Crystallization Behavior of Glycine from Mother Liquor

    Institute of Scientific and Technical Information of China (English)

    TAO Chang-yuan; LI Ming-song; FAN Xing; LIU Zuo-hua; DU Jun

    2011-01-01

    The mother liquor for preparing industrial HCN was investigated,to analyze the side-products' structure and influence of molecular interactions of side-products with glycine and solvent on the glycine's crystallization process.The side-products(SPs)were super-branched oligmers with plenty of hydrophilic groups,which could affect the crystallization process by interactions such as hydrogen bond.Alcohol-water mixed solvent with different polyols could be used to weaken the SPs-glycine interaction and strengthen the SPs-water interaction,which help to improve the crystallization efficiency and purity.After optimization,SPs' mass fraction in glycine could be reduced by 80%and the morphology of crystal particles could also be improved.

  16. Crystalline Morphology and Crystallization Characteristics of In-situ Blends of Anionic Polyamide 6 with Noncrystallizable Semiaromatic Polyamide Copolymer

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-chun; ZHENG Qiang; YANG Gui-sheng

    2007-01-01

    A noncrystallizable semiaromatic polyamide copolymer(NSAP) was dissolved in molten caprolactam, and PA6/NSAP blends were produced in-situ via the anionic ring-opening polymerization of caprolactam. The presence of a single loss tangent(tanδ) peak measured by means of dynamic mechanical analysis(DMA) proves the miscibility between PA6 and NSAP in the blends. It was found that there existed drastic changes in the crystallographic form and crystallization kinetics for the in-situ blends, e.g., when 20% NSAP was added, nearly all crystallites existed in the γ form and the crystallization could hardly occur upon cooling even at a rate of 2.5 ℃/min. Moreover, cold crystallization appears during the subsequent heating, and its melting point is 40 ℃ lower than that of the virgin system. On the other hand, the size of the spherulites only decreases modestly. It is suggested that the introduction of irregular stiff segments originated from NSAP into PA6 macromolecule chain, which resulted from transamidation during the polymerization play a dominant role in the drastic change of crystallization kinetics and the resultant morphology of the in-situ blends.

  17. Size-controlled anatase titania single crystals with octahedron-like morphology for dye-sensitized solar cells.

    Science.gov (United States)

    Shiu, Jia-Wei; Lan, Chi-Ming; Chang, Yu-Cheng; Wu, Hui-Ping; Huang, Wei-Kai; Diau, Eric Wei-Guang

    2012-12-21

    A simple hydrothermal method with titanium tetraisopropoxide (TTIP) as a precursor and triethanolamine (TEOA) as a chelating agent enabled growth in the presence of a base (diethylamine, DEA) of anatase titania nanocrystals (HD1-HD5) of controlled size. DEA played a key role to expedite this growth, for which a biphasic crystal growth mechanism is proposed. The produced single crystals of titania show octahedron-like morphology with sizes in a broad range of 30-400 nm; a typical, extra large, octahedral single crystal (HD5) of length 410 nm and width 260 nm was obtained after repeating a sequential hydrothermal treatment using HD3 and then HD4 as a seed crystal. The nanocrystals of size ~30 nm (HD1) and ~300 nm (HD5) served as active layer and scattering layer, respectively, to fabricate N719-sensitized solar cells. These HD devices showed greater V(OC) than devices of conventional nanoparticle (NP) type; the overall device performance of HD attained an efficiency of 10.2% power conversion at a total film thickness of 28 μm, which is superior to that of a NP-based reference device (η = 9.6%) optimized at a total film thickness of 18-20 μm. According to results obtained from transient photoelectric and charge extraction measurements, this superior performance of HD devices relative to their NP counterparts is due to the more rapid electron transport and greater TiO(2) potential. PMID:23116194

  18. Studies of fatty acid composition, physicochemical and thermal properties, and crystallization behavior of mango kernel fats from various Thai varieties.

    Science.gov (United States)

    Sonwai, Sopark; Ponprachanuvut, Punnee

    2014-01-01

    Mango kernel fat (MKF) has received attention in recent years due to the resemblance between its characteristics and those of cocoa butter (CB). In this work, fatty acid (FA) composition, physicochemical and thermal properties and crystallization behavior of MKFs obtained from four varieties of Thai mangoes: Keaw-Morakot (KM), Keaw-Sawoey (KS), Nam-Dokmai (ND) and Aok-Rong (AR), were characterized. The fat content of the mango kernels was 6.40, 5.78, 5.73 and 7.74% (dry basis) for KM, KS, ND and AR, respectively. The analysis of FA composition revealed that all four cultivars had oleic and stearic acids as the main FA components with ND and AR exhibiting highest and lowest stearic acid content, respectively. ND had the highest slip melting point and solid fat content (SFC) followed by KS, KM and AR. All fat samples exhibited high SFC at 20℃ and below. They melted slowly as the temperature increased and became complete liquids as the temperature approached 35°C. During static isothermal crystallization at 20°C, ND displayed the highest Avrami rate constant k followed by KS, KM and AR, indicating that the crystallization was fastest for ND and slowest for AR. The Avrami exponent n of all samples ranged from 0.89 to 1.73. The x-ray diffraction analysis showed that all MKFs crystallized into a mixture of pseudo-β', β', sub-β and β structures with β' being the predominant polymorph. Finally, the crystals of the kernel fats from all mango varieties exhibited spherulitic morphology. PMID:24919475

  19. Influences of Silver-Doping on the Crystal Structure, Morphology and Photocatalytic Activity of TiO2 Nanofibers

    DEFF Research Database (Denmark)

    Barakat, Nasser A. M.; Kanjwal, Muzafar Ahmed; Al-Deyab, Salem S.;

    2011-01-01

    Doping of titanium dioxide nanofibers by silver nanoparticles revealed distinct improvement in the photocatalytic activ-ity; however other influences have not been investigated. In this work, effect of sliver-doping on the crystal structure, the nanofibrous morphology as well as the photocatalytic...... activity of titanium oxide nanofibers has been studied. Sil-ver-doped TiO2 nanofibers having different silver contents were prepared by calcination of electrospun nanofiber mats consisting of silver nitrate, titanium isopropoxide and poly(vinyl acetate) at 600°C. The results affirmed formation of silver...

  20. Effects of Saponification Rate on Electrooptical Properties and Morphology of Poly(vinyl alcohol)/Liquid Crystal Composite Films

    Science.gov (United States)

    Ono, Hiroshi; Kawatsuki, Nobuhiro

    1995-03-01

    The relationship between the saponification rate of poly(vinyl alcohol) (PVA), and the electrooptical properties and morphology of the PVA/liquid crystal (LC) composite films was investigated. Light transmission clazing and the LC droplet size were varied by changing the saponification rate or the blend ratio of two kinds of PVA with different saponification rates because the refractive index and surface tension could be controlled by the saponification rate of PVA. The threshold voltage decreased with increasing saponification rate though the extrapolation length was decreased. It was suggested that the electrooptical properties were strongly dependent on the droplet size.

  1. Cryogenic Behavior of the High Temperature Crystal Oscillator PX-570

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Scherer, Steven

    2011-01-01

    Microprocessors, data-acquisition systems, and electronic controllers usually require timing signals for proper and accurate operation. These signals are, in most cases, provided by circuits that utilize crystal oscillators due to availability, cost, ease of operation, and accuracy. Stability of these oscillators, i.e. crystal characteristics, is usually governed, amongst other things, by the ambient temperature. Operation of these devices under extreme temperatures requires, therefore, the implementation of some temperature-compensation mechanism either through the manufacturing process of the oscillator part or in the design of the circuit to maintain stability as well as accuracy. NASA future missions into deep space and planetary exploration necessitate operation of electronic instruments and systems in environments where extreme temperatures along with wide-range thermal swings are countered. Most of the commercial devices are very limited in terms of their specified operational temperature while very few custom-made and military-grade parts have the ability to operate in a slightly wider range of temperature. Thus, it is becomes mandatory to design and develop circuits that are capable of operation efficiently and reliably under the space harsh conditions. This report presents the results obtained on the evaluation of a new (COTS) commercial-off-the-shelf crystal oscillator under extreme temperatures. The device selected for evaluation comprised of a 10 MHz, PX-570-series crystal oscillator. This type of device was recently introduced by Vectron International and is designed as high temperature oscillator [1]. These parts are fabricated using proprietary manufacturing processes designed specifically for high temperature and harsh environment applications [1]. The oscillators have a wide continuous operating temperature range; making them ideal for use in military and aerospace industry, industrial process control, geophysical fields, avionics, and engine

  2. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

    OpenAIRE

    Jie Liu; Xiaolong Lu; Chunrui Wu

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the over...

  3. Comparative Analysis of Thermal Behavior, Isothermal Crystallization Kinetics and Polymorphism of Palm Oil Fractions

    OpenAIRE

    Zhang, Xia; Li, Lin; Xie, He; Liang, Zhili; Su, Jianyu; Liu, Guoqin; Li, Bing

    2013-01-01

    Thermal behavior of palm stearin (PS) and palm olein (PO) was explored by monitoring peak temperature transitions by differential scanning calorimetry (DSC). The fatty acid composition (FAC), isothermal crystallization kinetics studied by pulsed Nuclear Magnetic Resonance (pNMR) and isothermal microstructure were also compared. The results indicated that the fatty acid composition had an important influence on the crystallization process. PS and PO both exhibited more multiple endotherms than...

  4. Chitosan/bentonite bionanocomposites: morphology and mechanical behavior; Bionanocompositos quitosana/bentonita: morfologia e comportamento mecanico

    Energy Technology Data Exchange (ETDEWEB)

    Braga, C.R.C.; Melo, F.M.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Programa de Pos-graduacao em Ciencia e Engenharia de Materiais; Vitorino, I.F. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Ciencia e Engenharia de Materiais; Fook, M.V.L.; Silva, S.M.L., E-mail: suedina@dema.ufcg.edu.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2010-07-01

    This study chitosan/bentonite bionanocomposite films were prepared by solution intercalation process, seeking to investigate the effect of the chitosan/bentonite ratio (5/1 e 10/1) on the morphology and mechanical behavior of the bionanocomposites. It was used as nanophase, Argel sodium bentonite (AN), was provided by Bentonit Uniao Nordeste-BUN (Campina Grande, Brazil) and as biopolymer matrix the chitosan of low molecular weight and degree of deacetylation of 86,7% was supplied by Polymar (Fortaleza, Brazil). The bionanocomposites was investigated by X-ray diffraction and tensile properties. According to the results, the morphology and the mechanical behavior of the bionanocomposite was affected by the ratio of chitosan/bentonite. The chitosan/bentonite ratio (5/1 and 10/1) indicated the formation of an intercalated nanostructure and of the predominantly exfoliated nanostructure, respectively. And the considerable increases in the resistance to the traction were observed mainly for the bionanocomposite with predominantly exfoliated morphology. (author)

  5. Trade-off between morphological convergence and opportunistic diet behavior in fish hybrid zone

    Directory of Open Access Journals (Sweden)

    Grey Jonathan

    2009-10-01

    Full Text Available Abstract Background The invasive Chondrostoma nasus nasus has colonized part of the distribution area of the protected endemic species Chondrostoma toxostoma toxostoma. This hybrid zone is a complex system where multiple effects such as inter-species competition, bi-directional introgression, strong environmental pressure and so on are combined. Why do sympatric Chondrostoma fish present a unidirectional change in body shape? Is this the result of inter-species interactions and/or a response to environmental effects or the result of trade-offs? Studies focusing on the understanding of a trade-off between multiple parameters are still rare. Although this has previously been done for Cichlid species flock and for Darwin finches, where mouth or beak morphology were coupled to diet and genetic identification, no similar studies have been done for a fish hybrid zone in a river. We tested the correlation between morphology (body and mouth morphology, diet (stable carbon and nitrogen isotopes and genomic combinations in different allopatric and sympatric populations for a global data set of 1330 specimens. To separate the species interaction effect from the environmental effect in sympatry, we distinguished two data sets: the first one was obtained from a highly regulated part of the river and the second was obtained from specimens coming from the less regulated part. Results The distribution of the hybrid combinations was different in the two part of the sympatric zone, whereas all the specimens presented similar overall changes in body shape and in mouth morphology. Sympatric specimens were also characterized by a larger diet behavior variance than reference populations, characteristic of an opportunistic diet. No correlation was established between the body shape (or mouth deformation and the stable isotope signature. Conclusion The Durance River is an untamed Mediterranean river despite the presence of numerous dams that split the river from

  6. A test of the coupling of predator defense morphology and behavior variation in two threespine stickleback populations

    OpenAIRE

    Jennyfer LACASSE, Nadia AUBIN-HORTH

    2012-01-01

    Among-population differences in morphology and behaviors such as boldness have been shown to co-vary with ecological conditions, including predation regime. However, between- and within-population covariation of predator defense morphology with variation in behaviors relevant to ecology and evolution (boldness, exploration, activity, sociability and aggressiveness, often defined as personality traits when they are consistent across time and contexts) have never been quantified together in a s...

  7. Bioleaching of incineration fly ash by Aspergillus niger – precipitation of metallic salt crystals and morphological alteration of the fungus

    Directory of Open Access Journals (Sweden)

    Tong-Jiang Xu

    2014-09-01

    Full Text Available This study examines the bioleaching of municipal solid waste incineration fly ash by Aspergillus niger, and its effect on the fungal morphology, the fate of the ash particles, and the precipitation of metallic salt crystals during bioleaching. The fungal morphology was significantly affected during one-step and two-step bioleaching; scanning electron microscopy revealed that bioleaching caused distortion of the fungal hyphae (with up to 10 μm hyphae diameter and a swollen pellet structure. In the absence of the fly ash, the fungi showed a linear structure (with 2–4 μm hyphae diameter. Energy-dispersive X-ray spectroscopy and X-ray diffraction confirmed the precipitation of calcium oxalate hydrate crystals at the surface of hyphae in both one-step and two-step bioleaching. Calcium oxalate precipitation affects bioleaching via the weakening of the fly ash, thus facilitating the release of other tightly bound metals in the matrix.

  8. Optimizing time and resource allocation trade-offs for investment into morphological and behavioral defense

    DEFF Research Database (Denmark)

    Steiner, Uli; Pfeiffer, Thomas

    2007-01-01

    Prey organisms are confronted with time and resource allocation trade-offs. Time allocation trade-offs partition time, for example, between foraging effort to acquire resources and behavioral defense. Resource allocation trade-offs partition the acquired resources between multiple traits......, such as growth or morphological defense. We develop a mathematical model for prey organisms that comprise time and resource allocation trade-offs for multiple defense traits. Fitness is determined by growth and survival during ontogeny. We determine optimal defense strategies for environments that differ...

  9. Crystal morphology modification by the addition of tailor-made stereocontrolled poly(N-isopropyl acrylamide)

    DEFF Research Database (Denmark)

    Munk, Tommy; Baldursdottir, Stefania; Hietala, Sami;

    2012-01-01

    The use of additives in crystallization of pharmaceuticals is known to influence the particulate properties critically affecting downstream processing and the final product performance. Desired functionality can be build into these materials, e.g. via optimized synthesis of a polymeric additive...

  10. Nonlinear flow behaviors of nematic liquid crystals in complex geometries

    Science.gov (United States)

    Araki, Takeaki

    2013-02-01

    We study nematic liquid crystals flowing in a regular-shaped porous medium by means of lattice Boltzmann simulations. With strong anchoring, the director field cannot align uniformly and topological defects are stably formed with a large number of possible configurations. In a quiescent state, each configuration is arrested since the energy barriers between possible configurations are higher than the thermal energy. If the flow speed is slow enough, the defect pattern is not changed from the initial quiescent configuration. Above a critical flow speed, the defect pattern transforms to a new stable configuration. In a regular-shaped porous matrix, there remain regularly aligned disclination loops. This regular pattern is maintained even after the flow is stopped.

  11. Simulated structural and magnetic behavior of Mn-Ti intercalated dichalcogenide crystals.

    Science.gov (United States)

    Roth, M W; Wandling, B; Kidd, T E; Shand, P M; Stollenwerk, A

    2016-05-11

    We present the results of extensive Monte Carlo simulations of intercalated manganese-titanium (Mn-Ti) layered TiS2 crystals. The computational model involves mixtures of Mn and Ti in various percentages placed on a triangular lattice with fixed lattice sites and up to five layers. The range of concentrations of intercalated Mn studied was 5%  ⩽  X Mn  ⩽  33% and for Ti, 0%  ⩽  X Ti  ⩽  15%, where X A denotes the percentage of the total number of lattice sites occupied by species A. The species are allowed to interact spatially through a screened Coulomb potential and magnetically with external and RKKY field terms. Structurally, the pure Mn systems present as disordered at very low densities and evolve through a 2  ×  2 structure (perfect at X Mn  =  25%) up to a [Formula: see text]  ×  [Formula: see text] lattice (perfect at X Mn  =  33%), with variations of the two 'perfect' lattice structures depending on density. Changes in density for pure Mn systems as well as those intercalated with both Mn and Ti dramatically affects the system's structural and magnetic properties, and the magnetic behavior of various morphological features present in the system are discussed. The RKKY interaction is adjusted based on the intercalant compositions and is very sensitive to structural variations in the intercalant layers. The composition ranges studied here encompass and exceed those that are experimentally accessible, which helps place experimentally relevant densities in perspective. PMID:27058645

  12. Simulated structural and magnetic behavior of Mn-Ti intercalated dichalcogenide crystals

    Science.gov (United States)

    Roth, M. W.; Wandling, B.; Kidd, T. E.; Shand, P. M.; Stollenwerk, A.

    2016-05-01

    We present the results of extensive Monte Carlo simulations of intercalated manganese-titanium (Mn-Ti) layered TiS2 crystals. The computational model involves mixtures of Mn and Ti in various percentages placed on a triangular lattice with fixed lattice sites and up to five layers. The range of concentrations of intercalated Mn studied was 5%  ⩽  X Mn  ⩽  33% and for Ti, 0%  ⩽  X Ti  ⩽  15%, where X A denotes the percentage of the total number of lattice sites occupied by species A. The species are allowed to interact spatially through a screened Coulomb potential and magnetically with external and RKKY field terms. Structurally, the pure Mn systems present as disordered at very low densities and evolve through a 2  ×  2 structure (perfect at X Mn  =  25%) up to a \\sqrt{3}   ×  \\sqrt{3} lattice (perfect at X Mn  =  33%), with variations of the two ‘perfect’ lattice structures depending on density. Changes in density for pure Mn systems as well as those intercalated with both Mn and Ti dramatically affects the system’s structural and magnetic properties, and the magnetic behavior of various morphological features present in the system are discussed. The RKKY interaction is adjusted based on the intercalant compositions and is very sensitive to structural variations in the intercalant layers. The composition ranges studied here encompass and exceed those that are experimentally accessible, which helps place experimentally relevant densities in perspective.

  13. Thermo-mechanical fatigue behavior of a single crystal nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, G.M., E-mail: gmhan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Yu, J.J.; Sun, X.F.; Hu, Z.Q. [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2011-07-25

    Highlights: {yields} The thermo-mechanical fatigue life of OP TMF is shorter than that of IP TMF. This is mainly attributed to the maximum tensile stress level at the minimum temperature. {yields} Under out-of-phase condition, damage is controlled by oxidation. While under in-phase condition, damage is controlled by creep. {yields} In terms of the fracture surface and microstructural evolution under different conditions, deformation and damage mechanisms are explained based on the relative contribution of oxidation, creep and fatigue. - Abstract: Thermo-mechanical fatigue (TMF) behavior in a <0 0 1> oriented nickel-based single crystal superalloy was investigated under different cycles of strain and temperature. Fracture surface and microstructural evolution were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. It was found that the fatigue lives under in-phase (IP) TMF were longer than those of out-of-phase (OP) TMF, and the maximum tensile stress level was concluded to be the lifetime-limiting factor. Compared to isothermal low-cycle fatigue (LCF) lives obtained under the maximum temperature 900 deg. C, thermo-mechanical fatigue lifetime was much shorter. This result indicates that varying temperature superimposed mechanical strain greatly reduces the fatigue lifetime of superalloys. Based on observation of fracture surface and microstructure evolution, it was concluded that creep is the dominant damage mechanism under IP-TMF condition and oxidation causes shorter lifetime for OP-TMF tests. The similarities and differences in the changes of {gamma}' morphology during in-phase (IP) and out-of-phase (OP) TMF tests were also discussed.

  14. Thermo-mechanical fatigue behavior of a single crystal nickel-based superalloy

    International Nuclear Information System (INIS)

    Highlights: → The thermo-mechanical fatigue life of OP TMF is shorter than that of IP TMF. This is mainly attributed to the maximum tensile stress level at the minimum temperature. → Under out-of-phase condition, damage is controlled by oxidation. While under in-phase condition, damage is controlled by creep. → In terms of the fracture surface and microstructural evolution under different conditions, deformation and damage mechanisms are explained based on the relative contribution of oxidation, creep and fatigue. - Abstract: Thermo-mechanical fatigue (TMF) behavior in a oriented nickel-based single crystal superalloy was investigated under different cycles of strain and temperature. Fracture surface and microstructural evolution were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. It was found that the fatigue lives under in-phase (IP) TMF were longer than those of out-of-phase (OP) TMF, and the maximum tensile stress level was concluded to be the lifetime-limiting factor. Compared to isothermal low-cycle fatigue (LCF) lives obtained under the maximum temperature 900 deg. C, thermo-mechanical fatigue lifetime was much shorter. This result indicates that varying temperature superimposed mechanical strain greatly reduces the fatigue lifetime of superalloys. Based on observation of fracture surface and microstructure evolution, it was concluded that creep is the dominant damage mechanism under IP-TMF condition and oxidation causes shorter lifetime for OP-TMF tests. The similarities and differences in the changes of γ' morphology during in-phase (IP) and out-of-phase (OP) TMF tests were also discussed.

  15. Remarkable crystallization morphologies of poly(4-vinylpyridine on single-walled carbon nanotubes in CO2-expanded liquids

    Directory of Open Access Journals (Sweden)

    Y. N. Wei

    2011-12-01

    Full Text Available Poly(4-vinylpyridine (P4VP is a widely studied polymer for applications in catalysis, humidity sensitive and antimicrobial materials due to its pyridine group exhibiting coordinative reactivity with transition metals. In this work, the non-covalent functionalization of single-walled carbon nanotubes (SWCNTs with P4VP in CO2-expanded liquids (CXLs is reported. It is found that P4VP stabilized SWCNTs show good dispersion in both organic solvent and aqueous solution (pH = 2. The ability to manipulate the dispersion state of CNTs in water with P4VP will likely benefit many biological applications, such as drug delivery and optical sensors. Furthermore, the structure and morphology of P4VP/SWCNTs composite are examined, with the focus on molecular weight of P4VP (MW-P4VP, the pressure of CXLs and the concentration of P4VP. It is amazing that the P4VP15470 wrapping patterns undergo a notable morphological evolution from dotlike crystals to bottle brush-like, then to compact kebab-like, and then to widely-spaced dotted kebab patterns by facile pressure tuning in the higher polymer concentration series. In other words, the CXLs method enables superior control of the P4VP crystallization patterns on SWCNTs. Meanwhile, the CXL-assisted P4VP crystal growth mechanism on SWCNT is investigated, and the dominating growth mechanism is attributed to ‘size dependent soft epitaxy’ in P4VP15470/SWCNTs composites. We believe these studies would r

  16. Fine control of perovskite-layered morphology and composition via sequential deposition crystallization process towards improved perovskite solar cells

    Science.gov (United States)

    Luo, Yi; Meng, Fanli; Zhao, Erfei; Zheng, Yan-Zhen; Zhou, Yali; Tao, Xia

    2016-04-01

    The ability to prepare high coverage and compact perovskite films via solution-based crystallization manipulation processes still represents a vital issue towards improving the ultimate photoelectric conversion efficiency of devices. In this work, we prepare the active perovskite layer by means of sequential deposition crystallization process i.e. dipping PbI2-infiltrated TiO2 film within CH3NH3I solution from 20s to 60s. The morphology and thickness of the as-prepared perovskite layer, and its overall performance superiority are investigated. X-ray diffraction (XRD) reveals that a maximum conversion of PbI2 to perovskite is completed upon applying a sequential deposition crystallization process of 40s. Field emission scanning electron microscope (FESEM) demonstrates that the coverage of the perovskite capping layer exhibits a trend from rise to decline in the whole dipping time from 20s to 60s. By fine control of the dipping time, a 620 nm-thickness compact perovskite active layer is obtained at the optimized dipping time of 40s and is verified to possess strong light absorption and high electron extraction efficiency, leading to a higher photocurrent. By further optimizing the mesoporous TiO2 film thickness, a high photocurrent of 23.98 mA cm-2 and an efficiency of 13.47% are achieved.

  17. Morphology-dependent field emission properties and wetting behavior of ZnO nanowire arrays

    Directory of Open Access Journals (Sweden)

    Ma Li

    2011-01-01

    Full Text Available Abstract The fabrication of three kinds of ZnO nanowire arrays with different structural parameters over Au-coated silicon (100 by facile thermal evaporation of ZnS precursor is reported, and the growth mechanism are proposed based on structural analysis. Field emission (FE properties and wetting behavior were revealed to be strongly morphology dependent. The nanowire arrays in small diameter and high aspect ratio exhibited the best FE performance showing a low turn-on field (4.1 V/μm and a high field-enhancement factor (1745.8. The result also confirmed that keeping large air within the films was an effective way to obtain super water-repellent properties. This study indicates that the preparation of ZnO nanowire arrays in an optimum structural model is crucial to FE efficiency and wetting behavior.

  18. The degradation and adsorption behaviors of enzyme on poly(butylene succinate) single crystals.

    Science.gov (United States)

    Jiang, Xi; Yang, Ju-Ping; Wang, Xiao-Hong; Zhou, Jian-Jun; Li, Lin

    2009-12-01

    The enzymatic degradation behavior of poly(butylene succinate) (PBS) single crystals with a lipase from Pseudomonas cepacia (lipase PS) is monitored using atomic force microscopy (AFM) in phosphate buffer at pH 6.8 and 40 degrees C. In-situ AFM results show that enzymatic degradation of the single crystal starts from the crystal edges rather than the chain-folded surfaces and the lamellar thickness remains constant during the whole degradation process. Total internal reflection fluorescence microscopy (TIRFM) is used for the first time to study the adsorption behavior of lipase onto the PBS crystal surface. The results clearly show that the enzyme molecules preferentially adsorb on the lateral surfaces of the single crystal but not on the chain-folded surfaces. AFM force-distance curve measurements and force-volume imaging obtained using a lipase-immobilized AFM tip show that small and large adhesive forces exist in the flat-on and edge-on areas of a PBS banded spherulite, respectively, which correspond to the chain-folded surface and lateral edges of a single crystal. PMID:19953521

  19. Molecular relaxation behavior and isothermal crystallization above glass transition temperature of amorphous hesperetin.

    Science.gov (United States)

    Shete, Ganesh; Khomane, Kailas S; Bansal, Arvind Kumar

    2014-01-01

    The purpose of this paper was to investigate the relaxation behavior of amorphous hesperetin (HRN), using dielectric spectroscopy, and assessment of its crystallization kinetics above glass transition temperature (Tg ). Amorphous HRN exhibited both local (β-) and global (α-) relaxations. β-Relaxation was observed below Tg , whereas α-relaxation prominently emerged above Tg . β-Relaxation was found to be of Johari-Goldstein type and was correlated with α-process by coupling model. Secondly, isothermal crystallization experiments were performed at 363 K (Tg + 16.5 K), 373 K (Tg + 26.5 K), and 383 K (Tg + 36.5 K). The kinetics of crystallization, obtained from the normalized dielectric strength, was modeled using the Avrami model. Havriliak-Negami (HN) shape parameters, αHN and αHN .βHN , were analyzed during the course of crystallization to understand the dynamics of amorphous phase during the emergence of crystallites. HN shape parameters indicated that long range (α-like) were motions affected to a greater extent than short range (β-like) motions during isothermal crystallization studies at all temperature conditions. The variable behavior of α-like motions at different isothermal crystallization temperatures was attributed to evolving crystallites with time and increase in electrical conductivity with temperature. PMID:24186540

  20. High-pressure studies on molecular crystals-relations between structure and high-pressure behavior

    Energy Technology Data Exchange (ETDEWEB)

    Orgzall, Ingo [Institut fuer Duennschichttechnologie und Mikrosensorik e.V., Kantstrasse 55, D-14513 Teltow (Germany); Emmerling, Franziska [Bundesanstalt fuer Materialforschung und -pruefung, Richard-Willstaetter-Strasse 11, D-12489 Berlin (Germany); Schulz, Burkhard [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14469 Potsdam (Germany); Franco, Olga [Heinrich-Heine-Universitaet Duesseldorf, Institut fuer Physikalische Chemie II, Universitaetsstrasse 1, Gebaeude 26.42.02, D-40225 Duesseldorf (Germany)], E-mail: orgzall@uni-potsdam.de, E-mail: franziska.emmerling@bam.de, E-mail: buschu@uni-potsdam.de, E-mail: olga.franco@uni-duesseldorf.de

    2008-07-23

    This paper summarizes attempts to understand structure-property relationships for a large class of aromatic diphenyl-1,3,4-oxadiazole molecules. Starting from the investigation of the crystal structure several common packing motifs as well as characteristic differences are derived. Many different molecules show a rather planar conformation in the solid state. A stronger intermolecular twist is only observed for compounds with substituents occupying the ortho-positions of the phenyl rings. Most crystal structures are characterized by the formation of stacks leading to intense {pi}-{pi} acceptor-donor interactions between oxadiazole and phenyl rings. High-pressure investigations result in a soft compression behavior typical for organic molecular crystals. The bulk behavior may be described by the Murnaghan equation of state with similar coefficients (bulk modulus and its pressure derivative) for nearly all investigated compounds but also for related substances. The compression shows a strong anisotropy resulting from the specific features and packing motifs of the crystal structure. This is clearly indicated by a corresponding strain analysis. Additionally to the crystal structure the Raman spectrum was also investigated under increasing pressure. The different pressure behavior of external and internal modes reflects the difference between intra- and intermolecular interactions.

  1. High-pressure studies on molecular crystals-relations between structure and high-pressure behavior

    International Nuclear Information System (INIS)

    This paper summarizes attempts to understand structure-property relationships for a large class of aromatic diphenyl-1,3,4-oxadiazole molecules. Starting from the investigation of the crystal structure several common packing motifs as well as characteristic differences are derived. Many different molecules show a rather planar conformation in the solid state. A stronger intermolecular twist is only observed for compounds with substituents occupying the ortho-positions of the phenyl rings. Most crystal structures are characterized by the formation of stacks leading to intense π-π acceptor-donor interactions between oxadiazole and phenyl rings. High-pressure investigations result in a soft compression behavior typical for organic molecular crystals. The bulk behavior may be described by the Murnaghan equation of state with similar coefficients (bulk modulus and its pressure derivative) for nearly all investigated compounds but also for related substances. The compression shows a strong anisotropy resulting from the specific features and packing motifs of the crystal structure. This is clearly indicated by a corresponding strain analysis. Additionally to the crystal structure the Raman spectrum was also investigated under increasing pressure. The different pressure behavior of external and internal modes reflects the difference between intra- and intermolecular interactions

  2. EFFECTS OF COUPLING AGENTS ON THE CRYSTALLIZATION BEHAVIOR OF PP/T-ZnOw COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objectives of this paper are to understand the crystallization behavior of polypropylene (PP) composites with surface modified tetra-needle-shaped zinc oxide whisker (T-ZnOw). T-ZnOw was surface modified with different coupling agents, such as silane coupling agents (KH-550, KH-560) and titanate coupling agent (NDZ-105), in order to improve the compatibility between PP and T-ZnOw. DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites, respectively. The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization, depending on the coupling agent used for modification. KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size. The results also suggest that the crystallization behavior depends on not only the content of coupling agent, but also the content of the surface modified T-ZnOw used in the composites.

  3. Morphological and Structural Control of Organic Monolayer Colloidal Crystal Based on Plasma Etching and Its Application in Fabrication of Ordered Gold Nanostructured Arrays

    Directory of Open Access Journals (Sweden)

    Guangqiang Liu

    2016-09-01

    Full Text Available The organic monolayer colloidal crystals, which are usually prepared by self-assembling, could be used as templates, due to their interstitial geometry, for the periodically arranged nanostructured arrays, which have important applications in many fields, such as photonic crystals, information storage, super-hydrophobicity, biological and chemical sensing. Obviously, the structures of the obtained arrays mainly depend on those of the templates. However, the self-assembled monolayer colloidal crystal is exclusive in structure and for its hexagonal close-packed colloidal arrangement, leading to the limitation of the monolayer colloidal crystal as the template for the nanostructured arrays. Therefore, structural diversity is important in order for colloidal crystals to be used as the templates for various nanostructured arrays. Recently, there have been some reports on the morphological and structural manipulation of the organic monolayer colloidal crystals. In this review article, we focus on the recent progress in morphological and structural manipulation of polystyrene monolayer colloidal crystals based on plasma etching, and its application in the fabrication of the ordered gold nanostructured arrays with different structures, mainly including close-packed monolayer colloidal crystal and its transferrable property; structural manipulation based on plasma etching; and fabrication of gold nanostructured arrays based on varied monolayer colloidal crystals as template.

  4. Effects of monomer functionality on performances of scaffolding morphologic transmission gratings recorded in polymer dispersed liquid crystals

    International Nuclear Information System (INIS)

    The effects of monomer functionality on performances of holographic polymer dispersed liquid crystal (HPDLC) transmission gratings are systematically investigated. Acrylate monomers with an average functionality ranging from 2.0 to 5.0 are used to prepare these samples. We find scaffolding morphologic transmission gratings (characterized by a high phase separation degree, a well alignment of LCs and low scattering loss) can be obtained irrespective of the monomer functionality, although the exact optimal curing intensity varies. The temporal evolution of the grating formation is studied and the onset time of the LC phase separation decreases significantly with the increase in average monomer functionality. It is also shown that the gratings prepared from low average functionality monomers require a comparatively low switch-off electric field (∼8 V μm−1) whilst suffering from mechanical fragility and long-term instability. Our results not only provide a complete understanding of scaffolding morphologic gratings in terms of the material composition effect, but also provide insight into the formation mechanisms of non-droplet morphologic HPDLC gratings. (paper)

  5. Effect of n-HA content on the isothermal crystallization, morphology and mechanical property of n-HA/PLGA composites

    Energy Technology Data Exchange (ETDEWEB)

    Liuyun, Jiang, E-mail: jlytxg@163.com [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Chengdong, Xiong [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Lixin, Jiang [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China); Graduated School of Chinese Academy of Sciences, Beijing 100039 (China); Dongliang, Chen; Qing, Li [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041 (China)

    2013-03-15

    Graphical abstract: Effect of n-HA content on the isothermal crystallization, morphology and mechanical property of n-HA/PLGA composites was studied in details. The results showed that the addition of higher content of g-n-HA was favorable to promote the crystallization better in g-n-HA/PLGA composites, but it could also cause more agglomeration in PLGA matrix, as a result of worse mechanical properties, and the addition content of 3 wt% g-n-HA to PLGA matrix was an appropriate proportion, which had the highest bending strength among these g-n-HA/PLGA composites, and it might be potential to be used in biomedical fields in future. Highlights: ► The effect of n-HA content on the n-HA/PLGA composites was studied in detail. ► Isothermal crystallization, microstructure and mechanical property were studied. ► The relation between n-HA content and properties of n-HA/PLGA composite was found. ► An appropriate proportion of n-HA in n-HA/PLGA composite was obtained. - Abstract: A serials of g-n-HA/PLGA composites with surface-modified g-n-HA of 1%, 3%, 6%, 10% and 15% in weight were prepared by solution mixing. The isothermal crystallization, morphology and mechanical property of g-n-HA/PLGA composites were investigated by differential scanning calorimeter (DSC), scanning electron microscope (SEM) and electromechanical universal tester. The results showed that Avrami equation was suitable for describing the isothermal crystallization process in this system, and the crystallization rate of g-n-HA/PLGA composites containing more than 3 wt% g-n-HA was basically accord with the relational expression of T{sub 110} {sub °C} > T{sub 105°C} > T{sub 115°C} > T{sub 120°C}. Moreover, at the same Tc, crystallization rate was greatly enhanced with the increasing of g-n-HA acting as nucleate. However, the addition of higher content of g-n-HA would cause more agglomeration in PLGA matrix, so that the mechanical properties of g-n-HA/PLGA composites would gradually decrease. In

  6. Crystallization Kinetics and Melting Behavior of PA1010/Ether-based TPU Blends

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-ling; ZHAO Yan; SUN Xiao-bo; JIANG Zhen-hua; WU Zhong-wen; WANG Gui-Bin

    2007-01-01

    Polyamide 1010(PA1010)/thermoplastic poly(ether urethane) elastomer(ether-based TPU) blends were prepared via melt extrusion. The crystallization kinetics and melting behavior of PA1010/ether-based TPU blends were systematically investigated using differential scanning calorimetry. The crystallization kinetics results show that the addition of ether-based TPU hinders the crystallization of PA1010, and the hindrance effect increases with the increase of the concentration of ether-based TPU. Both pure PA1010 and PA1010/ether-based TPU blends exhibit double melting peaks in the process of nonisothermal crystallization. The double melting peaks change differently with the variation of cooling rate and blend composition. The cooling rate only influences the lower melting peak; however, the blend composition influences not only the lower melting peak but also the higher melting peak. The reason for the phenomenon must be the interaction between the two compositions.

  7. Global weak solution and large-time behavior for the compressible flow of liquid crystals

    CERN Document Server

    Wang, Dehua

    2011-01-01

    The three-dimensional equations for the compressible flow of liquid crystals are considered. An initial-boundary value problem is studied in a bounded domain with large data. The existence and large-time behavior of a global weak solution are established through a three-level approximation, energy estimates, and weak convergence for the adiabatic exponent $\\gamma>\\frac32$.

  8. Crystallization behavior of supercooled smectic cholesteryl myristate nanoparticles containing phospholipids as stabilizers

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Koch, Michel; Drechsler, M;

    2005-01-01

    recrystallization tendency upon storage. The observed peculiarities of the crystallization behavior seem to be mainly caused by the presence of particles with different shapes (cylindrical and spherical) as observed in electron microscopy. Alterations in the composition of the nanoparticles may also play a role....

  9. Aircraft noise exposure affects rat behavior, plasma norepinephrine levels, and cell morphology of the temporal lobe.

    Science.gov (United States)

    Di, Guo-Qing; Zhou, Bing; Li, Zheng-Guang; Lin, Qi-Li

    2011-12-01

    In order to investigate the physiological effects of airport noise exposure on organisms, in this study, we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 d. For comparison, we also used unexposed control rats. Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels (L(WECPN)) of 75 and 80 dB for the two experimental groups. We examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD). We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM). Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number (Paircraft noise of 80 dB exposure for 65 d. In conclusion, exposing rats to long-term aircraft noise affects their behaviors, plasma NE levels, and cell morphology of the temporal lobe. PMID:22135145

  10. Ontogenetic development in the morphology and behavior of loach ( Misgurnus anguillicaudatus) during early life stages

    Science.gov (United States)

    Gao, Lei; Duan, Ming; Cheng, Fei; Xie, Songguang

    2014-09-01

    Loach ( Misgurnus anguillicaudatus) are a commercially important fish in China and an ideal aquaculture species. However, culturists experience high larval and juvenile mortality during mass production. To provide insight into ways to improve larviculture techniques, we describe the morphological characteristics and behavior of loach during the larval and early juvenile stages. Yolksac larvae ranged from 2.8 to 4.0 mm body length (BL) between days 0 to 4; preflexion larvae ranged from 3.6 to 5.5 mm BL between days 4 to 6; flexion larvae ranged from 4.8 to 8.1 mm BL between days 5 and 14; and postflexion larvae ranged from 7.1 to 15.7 mm BL between days 11 to 27; the minimum length and age of juveniles was 14.1 mm BL and 23 d, respectively. Loach are demersal from hatch through to the early juvenile stages. A suite of morphological characteristics (e.g., external gill filament and ventral mouth opening) and behavioral traits have developed to adapt to demersal living. We observed positive allometric growth in eye diameter, head length, head height, and pectoral fin length during the early larval stages, reflecting the priorities in the development of the organs essential for survival. Our results provide a basis for developing techniques to improve the survival of larval and juvenile loach during mass production.

  11. Aircraft noise exposure affects rat behavior, plasma norepinephrine levels, and cell morphology of the temporal lobe

    Institute of Scientific and Technical Information of China (English)

    Guo-qing DI; Bing ZHOU; Zheng-guang; LI, Qi-li LIN

    2011-01-01

    In order to investigate the physiological effects of airport noise exposure on organisms,in this study,we exposed Sprague-Dawley rats in soundproof chambers to previously recorded aircraft-related noise for 65 d.For comparison,we also used unexposed control rats.Noise was arranged according to aircraft flight schedules and was adjusted to its weighted equivalent continuous perceived noise levels (LwEcPN) of 75 and 80 dB for the two experimental groups.We examined rat behaviors through an open field test and measured the concentrations of plasma norepinephrine (NE) by high performance liquid chromatography-fluorimetric detection (HPLC-FLD).We also examined the morphologies of neurons and synapses in the temporal lobe by transmission electron microscopy (TEM).Our results showed that rats exposed to airport noise of 80 dB had significantly lower line crossing number (P<0.05) and significantly longer center area duration (P<0.05) than control animals.After 29 d of airport noise exposure,the concentration of plasma NE of exposed rats was significantly higher than that of the control group (P<0.05).We also determined that the neuron and synapsis of the temporal lobe of rats showed signs of damage after aircraft noise of 80 dB exposure for 65 d.In conclusion,exposing rats to long-term aircraft noise affects their behaviors,plasma NE levels,and cell morphology of the temporal lobe.

  12. GROWTH OF CRYSTALS OF PRIMARY ALUMINIUM WITH ROSETTE MORPHOLOGY AT CASTING OF SILUMINS

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2011-01-01

    Full Text Available The work is devoted to actual theme of alloy solidifi – investigation of infl of overlapping of thermal and concentration fi of neighboring crystals to forming of non- dendrite structures. Experimental research of microstructure of Al-Si alloy for wide range of silicon concentration is conducted, and corresponding numerical simulation develop too. The conclusion about different schemes of forming of rosette structures is adopted.

  13. Crystallization kinetics and morphology in phase separating and sedimenting mixtures of colloidal spheres and rods

    OpenAIRE

    Lekkerkerker, H.N.W.; Oversteegen, S.M.; Wijnhoven, J.E.G.J.; Vonk, C.

    2004-01-01

    The crystallization of sedimentating silica spheres in the presence of silica-coated boehmite rods in low-salt dimethylformamide is studied by means of confocal scanning laser microscopy. As expected, addition of rods gives rise to a net attraction due to the depletion effect. Upon increasing rod volume fractions, below a predicted equilibrium binodal, crystalline ordering of the spheres takes place faster but gives cause for more grain boundaries. Addition of rods at volume fractions in the ...

  14. Anomalous swimming behavior of bacteria in nematic liquid crystals

    Science.gov (United States)

    Sokolov, Andrey; Zhou, Shuang; Lavrentovich, Oleg; Aranson, Igor

    2015-03-01

    Flagellated bacteria stop swimming in isotropic media of viscosity higher than 0.06kgm-1s-1. However, Bacillus Subtilis slows down by only about 30% in a nematic chromonic liquid crystal (CLC, 14wt% DSCG in water), where the anisotropic viscosity can be as high as 6kgm-1s-1. The bacteria velocity (Vb) is linear with the flagella rotation frequency. The phase velocity of the flagella Vf ~ 2Vb in LC, as compared to Vf ~ 10Vb in water. The flow generated by the bacteria is localized along the bacterial body axis, decaying slowly over tens of micrometers along, but rapidly over a few micrometers across this axis. The concentrated flow grants the bacteria new ability to carry cargo particles in LC, ability not seen in their habitat isotropic media. We attribute these anomalous features to the anisotropy of viscosity of the CLC, namely, the viscosities of splay and twist is hundreds times higher than that of bend deformation, which provides extra boost of swimming efficiency and enables the bacteria swim at considerable speed in a viscous medium. Our findings can potentially lead to applications such as particle transportation in microfluidic devices. A.S and I.A are supported by the US DOE, Office of Science, BES, Materials Science and Engineering Division. S.Z. and O.D.L are supported by NSF DMR 1104850, DMS-1434185.

  15. Relationship of sow udder morphology with piglet suckling behavior and teat access.

    Science.gov (United States)

    Balzani, Agnese; Cordell, Heather J; Edwards, Sandra A

    2016-11-01

    The aim of this study was to investigate if there is a relationship between the latency to the first suckling and udder and teat morphology and to assess the extent to which piglet and sow characteristics influence teat pair position preference. Udder morphology trait measurements, piglet suckling behavior, and sow productive and behavioral traits were recorded from a population of 74 Large White X Landrace sows of different parities. The interteat distance within the same row was larger between the teats that were suckled at the first contact with the udder compared with the unsuckled teats (P = 0.04). There was a tendency for piglets to suckle first from teats placed closer to the abdominal midline. A high proportion of siblings (64%) suckled for the first time on a teat previously chosen by another piglet. Most neonates suckled first from a teat located in the posterior part of the udder (41%) or in the anterior part (33%), rather than the middle section. Latency from birth to suckling and the time from the first udder contact to locate a teat and suckle was shorter for piglets first suckling the anterior (28:03 and 9:48 minutes) and posterior teats (26:31; 8:38 minutes) than for those sucking the midsection teats (34:30 minutes, F7,256 = 1.99, P = 0.05; 10:30, F7,256 = 2.37, P = 0.05). To avoid possible confounds, other potential causes of delay in successful suckling were studied. The latency to suckle was not influenced by piglet vitality score at birth, weight, or provision of human assistance to place it at the udder. It was shorter when the piglets were born later in the litter (P piglets born dead (P = 0.001) and from a sow with an induced farrowing (P = 0.007). Moreover, there was a tendency for piglets born from a multiparous sow (P = 0.06) and in a large litter size (P = 0.07) to have a longer latency to find a teat and suckle once they had made the first contact with the udder. Although suckling itself is clearly an instinctive

  16. Tailoring of morphology and crystal structure of CdSe nanostructures by controlling the ratio of triethylenetetraamine and water in their mixed solution

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, M.R.; Zarghami, V. [Sharif University of Technology, Department of Materials Science and Engineering, Tehran (Iran, Islamic Republic of); Fray, D.J. [University of Cambridge, Department of Materials Science and Metallurgy, Cambridge (United Kingdom)

    2012-05-15

    The morphological manipulation, structural characterization, and optical properties of different CdSe nanocrystals were reported. Several different CdSe nanostructures, including nanowires, tetrapod crystals, and nanoparticles were grown by varying the volume ratio of triethylenetetraamine (TETA) and water (WA) in their mixed solution. By manipulating the growth driving force (i.e., the degree of supersaturation) and kinetics of the process (i.e., growth rate), the morphology and crystal structure of CdSe nanocrystals can be tailored. Growth driving force changed their morphology from nanowires to tetrapod structures and from the latter structure to nanoparticles. Moreover, kinetics of the process altered their crystal structure from wurtzite to zinc blende. The optical property of CdSe nanocrystals was investigated using UV-vis spectroscopy. The absorption edge of CdSe nanostructures showed a blue shift. CdSe nanocrystals prepared under optimized conditions showed good microstructural and optical properties for solar cell application. (orig.)

  17. Additives Effects on Crystal Morphology of Dihydroxylammonium 5,5ʹ-Bistetrazole-1,1ʹ-diolate by Molecular Dynamics Simulations

    Science.gov (United States)

    Xiong, Shu-Ling; Chen, Shu-Sen; Jin, Shao-Hua; Li, Li-Jie

    2016-10-01

    Dihydroxylammonium 5,5‧-bistetrazole-1,1‧-diolate (TKX-50) is a newly synthesized explosive with excellent comprehensive properties: high energy storage, low impact sensitivity, and low toxicity. To understand and improve the crystal morphology of TKX-50, we reported the polymer consistent force field to simulate the crystal morphology of TKX-50 by growth morphology (GM) method. We then used this force field in molecular dynamics (MD) simulations to predict the influences of additives on crystal facets of TKX-50. The calculated results indicate that ethanol, ethylene glycol, and acetic acid are more favorable to the spheroidization of TKX-50, which provides a theoretical support for the additive selection of crystalline system. Furthermore, we added the selected additives in the recrystallization system of TKX-50. The recrystallized samples possessed a small aspect ratio and were close to spherical in shape, which indicates that the experimental results are consistent with the simulated results.

  18. A test of the coupling of predator defense morphology and behavior variation in two threespine stickleback populations

    Directory of Open Access Journals (Sweden)

    Jennyfer LACASSE, Nadia AUBIN-HORTH

    2012-02-01

    Full Text Available Among-population differences in morphology and behaviors such as boldness have been shown to co-vary with ecological conditions, including predation regime. However, between- and within-population covariation of predator defense morphology with variation in behaviors relevant to ecology and evolution (boldness, exploration, activity, sociability and aggressiveness, often defined as personality traits when they are consistent across time and contexts have never been quantified together in a single study in juvenile fish from populations found in contrasting environments. We measured predator defense morphology differences between adults from two freshwater populations of threespine sticklebacks with different ecological conditions. We then quantified five behaviors in juveniles from both populations raised in a common environment. Wild-caught adults showed significant differences in predator defense morphology. One population had significantly lower lateral plate number, shorter dorsal spine, pelvic spine and pelvic girdle. Furthermore, 61% of individuals from that population showed an absence of pelvic spine and girdle. At the population level, we found that differences in defense morphology in adults between the two lakes were coupled with differences in behaviors in juveniles raised in a common environment. Levels of activity, aggressiveness and boldness were higher in juveniles from the population lacking predator defense structures. At the individual level, anti-predator morphology of adult females could not predict their offspring’s behavior, but juvenile coloration predicted individual boldness in a population-specific manner. Our results suggest that ecological conditions, as reflected in adult predator defense morphology, also affect juvenile behavior in threespine sticklebacks, resulting in trait co-specialization, and that there is a genetic or epigenetic component to these behavioral differences [Current Zoology 58 (1: 53–65, 2012].

  19. A test of the coupling of predator defense morphology and behavior variation in two threespine stickleback populations

    Institute of Scientific and Technical Information of China (English)

    Jennyfer LACASSE; Nadia AUBIN-HORTH

    2012-01-01

    Among-population differences in morphology and behaviors such as boldness have been shown to co-vary with ecological conditions,including predation regime.However,between- and within-population covariation of predator defense morphology with variation in behaviors relevant to ecology and evolution (boldness,exploration,activity,sociability and aggressivehess,often defined as personality traits when they are consistent across time and contexts) have never been quantified together in a single study in juvenile fish from populations found in contrasting environments.We measured predator defense morphology differences between adults from two freshwater populations of threespine sticklebacks with different ecological conditions.We then quantified five behaviors in juveniles from both populations raised in a common environment.Wild-caught adults showed significant differences in predator defense morphology.One population had significantly lower lateral plate number,shorter dorsal spine,pelvic spine and pelvic girdle.Furthermore,61% of individuals from that population showed an absence of pelvic spine and girdle.At the population level,we found that differences in defense morphology in adults between the two lakes were coupled with differences in behaviors in juveniles raised in a common environment.Levels of activity,aggressiveness and boldness were higher in juveniles from the population lacking predator defense structures.At the individual level,anti-predator morphology of adult females could not predict their offspring's behavior,but juvenile coloration predicted individual boldness in a population-specific manner.Our results suggest that ecological conditions,as reflected in adult predator defense morphology,also affect juvenile behavior in threespine sticklebacks,resulting in trait co-specialization,and that there is a genetic or epigenetic component to these behavioral differences [Current Zoology 58 ( 1 ):53--65,2012].

  20. Quasi-two-dimensional diamond crystals: Deposition from a gaseous phase and structural-morphological properties

    Science.gov (United States)

    Alexeev, A. M.; Ismagilov, R. R.; Ashkinazi, E. E.; Orekhov, A. S.; Malykhin, S. A.; Obraztsov, A. N.

    2016-07-01

    Diamond films predominantly consisting of plane micrometer-size crystallites with a thickness of several dozen nanometers have been deposited from a methane-hydrogen gas mixture activated by a dc gas discharge. The crystallite structure has been studied by scanning and transmission electron microscopy and diffraction. A possible mechanism of formation of plane crystallites during deposition of diamond from the gas phase has been discussed. It has been shown that the results agree with the theoretical concepts of formation of crystals with a face-centered cubic lattice.

  1. Hydrothermal growth of beryl single crystals and morphology of their singular faces

    International Nuclear Information System (INIS)

    The surface morphology of the best developed faces of emerald and red beryl monocrystals grown from high-temperature hydrothermal solutions has been studied by atomic force microscopy. The results attest to dislocation-mediated layer-by-layer growth of the faces. Using experimentally determined growth front profiles, the fractal dimensions DFp and DFa of the faces are evaluated to be 1.1-1.4. These values indicate that the surfaces studied have a fractal character and can be investigated using elements of fractal theory

  2. Crystallization of poly(ethylene oxide) with acetaminophen--a study on solubility, spherulitic growth, and morphology.

    Science.gov (United States)

    Yang, Min; Gogos, Costas

    2013-11-01

    A simple, sensitive, efficient, and novel method analyzing the number of spherulitic nuclei was proposed to estimate the solubility of a model drug acetaminophen (APAP) in poly(ethylene oxide) (PEO). At high crystallization temperature (323 K), 10% APAP-PEO had the same low number of spherulitic nuclei as pure PEO, indicating that APAP and PEO were fully miscible. At low crystallization temperature (303 K), the number of nuclei for 10% APAP-PEO was significantly higher, suggesting that APAP was oversaturated and therefore recrystallized and acted as a nucleating agent. Based on the results obtained, the solubility of APAP in PEO is possibly between the concentration of 0.1% and 1% at 303 K. The spherulitic growth rate G of PEO was found to decrease with increasing APAP concentration, suggesting that APAP is most likely functioning as a chemical defect and is either rejected from or included in the PEO crystals during chain folding. APAP could possibly locate in the inter-spherulitic, inter-fibrillar, inter-lamellar, or intra-lamellar regions of PEO. At 323 K, the morphology of 10% APAP-PEO is more dendritic than spherulitic with large unfilled space in between dendrites and spherulites, which is a sign of one or the combination of the four modes of segregation. An extensive spherulitic nucleation and growth kinetics study using the classical theoretical relationships, for example, the Hoffman-Lauritzen (HL) and Avrami theories, was conducted. Both microscopic and differential scanning calorimetric (DSC) analysis yielded similar values for the nucleation constant Kg as well as the fold surface free energy σe and work of chain folding q. The values of σe and q increased with APAP concentration, indicating that the chain folding of PEO was hindered by APAP. PMID:23562611

  3. Structure, surface area and morphology of aluminas from thermal decomposition of Al(OH(CH3COO2 crystals

    Directory of Open Access Journals (Sweden)

    KIYOHARA PEDRO K.

    2000-01-01

    Full Text Available Crystalline aluminium hydroxiacetate was prepared by reaction between aluminium powder (ALCOA 123 and aqueous solution of acetic acid at 96ºC ±1ºC. The white powder of Al(OH(CH3COO2 is constituted by agglomerates of crystalline plates, having size about 10mum. The crystals were fired from 200ºC to 1550ºC, in oxidizing atmosphere and the products characterized by X-ray diffraction, scanning electron microscopy and surface area measurements by BET-nitrogen method. Transition aluminas are formed from heating at the following temperatures: gamma (300ºC; delta (750ºC; alpha (1050ºC. The aluminas maintain the original morphology of the Al(OHAc2 crystal agglomerates, up to 1050ºC, when sintering and coalescence of the alpha-alumina crystals start and proceed up to 1550ºC. High surface area aluminas are formed in the temperature range of 700ºC to 1100ºC; the maximum value of 198m²/g is obtained at 900ºC, with delta-alumina structure. The formation sequence of transition aluminas is similar to the sequence from well ordered boehmite, but with differences in the transition temperatures and in the development of high surface areas. It is suggested that the causes for these diversities between the two sequences from Al(OH Ac2 and boehmite are due to the different particle sizes, shapes and textures of the gamma-Al2O3 which acts as precursor for the sequence gamma- to alpha-Al2O3.

  4. Adaptive evolution of a derived radius morphology in manakins (Aves, Pipridae) to support acrobatic display behavior.

    Science.gov (United States)

    Friscia, Anthony; Sanin, Gloria D; Lindsay, Willow R; Day, Lainy B; Schlinger, Barney A; Tan, Josh; Fuxjager, Matthew J

    2016-06-01

    The morphology of the avian skeleton is often studied in the context of adaptations for powered flight. The effects of other evolutionary forces, such as sexual selection, on avian skeletal design are unclear, even though birds produce diverse behaviors that undoubtedly require a variety of osteological modifications. Here, we investigate this issue in a family of passerine birds called manakins (Pipridae), which have evolved physically unusual and elaborate courtship displays. We report that, in species within the genus Manacus, the shaft of the radius is heavily flattened and shows substantial solidification. Past work anecdotally notes this morphology and attributes it to the species' ability to hit their wings together above their heads to produce loud mechanical sonations. Our results show that this feature is unique to Manacus compared to the other species in our study, including a variety of taxa that produce other sonations through alternate wing mechanisms. At the same time, our data reveal striking similarities across species in total radius volume and solidification. Together, this suggests that supposedly adaptive alterations in radial morphology occur within a conserved framework of a set radius volume and solidness, which in turn is likely determined by natural selection. Further allometric analyses imply that the radius is less constrained by body size and the structural demands that underlie powered flight, compared to other forelimb bones that are mostly unmodified across taxa. These results are consistent with the idea that the radius is more susceptible to selective modification by sexual selection. Overall, this study provides some of the first insight into the osteological evolution of passerine birds, as well as the way in which opposing selective forces can shape skeletal design in these species. J. Morphol. 277:766-775, 2016. © 2016 Wiley Periodicals, Inc. PMID:27027525

  5. Artificial water sediment regulation scheme influences morphology, hydrodynamics and nutrient behavior in the Yellow River estuary

    Science.gov (United States)

    Xu, Bochao; Yang, Disong; Burnett, William C.; Ran, Xiangbin; Yu, Zhigang; Gao, Maosheng; Diao, Shaobo; Jiang, Xueyan

    2016-08-01

    Anthropogenic controls on water and sediment may play important roles in river system transformations and morphological evolution, which could further affect coastal hydrodynamics and nutrient behavior. We used geochemical tracers to evaluate the influence of an intentional large release of water and sediment during the so-called "Water Sediment Regulation Scheme" (WSRS) on estuarine morphology, hydrodynamics and nutrients in the Yellow River estuary, China. We discovered that there was a newly formed small delta in the river mouth after the 2013 WSRS. This new morphologic feature altered terrestrial material distribution patterns from a single plume to a two-plume pattern within the estuary. Our results show that the WSRS significantly influenced the study area in the following ways: (1) Radium and nutrient concentrations were significantly elevated (two to four times), especially along the two river outlets. (2) Estuarine mixing was about two times stronger during WSRS than before. Average aerial mixing rates before and during WSRS were 50 ± 26 km2 d-1 and 89 ± 51 km2 d-1, respectively. (3) Our data is consistent with P limitation and suggest that stoichiometrically based P limitation was even more severe during WSRS. (4) All river-derived nutrients were thoroughly consumed within one to two weeks after entry to near-shore waters. (5) The extent of the area influenced by terrestrial nutrients was two to three times greater during WSRS. Human influence, such as triggered by WSRS regulations, should thus be considered when studying biogeochemical processes and nutrient budgets in situations like the Yellow River estuary.

  6. Effect of pH on the morphology, mechanical and optical properties of L-arginine monohydrobromide monohydrate (LAHBr) single crystals

    Indian Academy of Sciences (India)

    K Sangeetha; R Ramesh Babu; K Ramamurthi

    2015-09-01

    L-arginine monohydrobromide monohydrate (LAHBr) single crystals were grown from two molar mixtures of L-arginine and HBr acid in 1 : 2 and 1 : 3 ratios. The solution pH of the above molar ratios was measured to be 7.2 and 1.8, respectively. This drastic change in pH has modified the morphology of LAHBr single crystal and influenced the mechanical stability, optical transparency, refractive index, birefringence and laser damage threshold. The decrease in pH from 7.2 to 1.8 has enhanced the optical transparency and laser damage threshold of LAHBr crystal.

  7. Quantity effect of radial cracks on the cracking propagation behavior and the crack morphology.

    Directory of Open Access Journals (Sweden)

    Jingjing Chen

    Full Text Available In this letter, the quantity effect of radial cracks on the cracking propagation behavior as well as the circular crack generation on the impacted glass plate within the sandwiched glass sheets are experimentally investigated via high-speed photography system. Results show that the radial crack velocity on the backing glass layer decreases with the crack number under the same impact conditions during large quantities of repeated experiments. Thus, the "energy conversion factor" is suggested to elucidate the physical relation between the cracking number and the crack propagation speed. Besides, the number of radial crack also takes the determinative effect in the crack morphology of the impacted glass plate. This study may shed lights on understanding the cracking and propagation mechanism in laminated glass structures and provide useful tool to explore the impact information on the cracking debris.

  8. Restricted morphological and behavioral abnormalities following ablation of β-actin in the brain.

    Directory of Open Access Journals (Sweden)

    Thomas R Cheever

    Full Text Available The local translation of β-actin is one mechanism proposed to regulate spatially-restricted actin polymerization crucial for nearly all aspects of neuronal development and function. However, the physiological significance of localized β-actin translation in neurons has not yet been demonstrated in vivo. To investigate the role of β-actin in the mammalian central nervous system (CNS, we characterized brain structure and function in a CNS-specific β-actin knock-out mouse (CNS-ActbKO. β-actin was rapidly ablated in the embryonic mouse brain, but total actin levels were maintained through upregulation of other actin isoforms during development. CNS-ActbKO mice exhibited partial perinatal lethality while survivors presented with surprisingly restricted histological abnormalities localized to the hippocampus and cerebellum. These tissue morphology defects correlated with profound hyperactivity as well as cognitive and maternal behavior impairments. Finally, we also identified localized defects in axonal crossing of the corpus callosum in CNS-ActbKO mice. These restricted defects occurred despite the fact that primary neurons lacking β-actin in culture were morphologically normal. Altogether, we identified novel roles for β-actin in promoting complex CNS tissue architecture while also demonstrating that distinct functions for the ubiquitously expressed β-actin are surprisingly restricted in vivo.

  9. Phase behavior and crystallization in blends of a low molecular weight polyethylene-block-poly(ethylene oxide) diblock copolymer and poly(hydroxyether of bisphenol A)

    International Nuclear Information System (INIS)

    The phase behavior, morphology and crystallization in blends of a low-molecular-weight (M n = 1400) double-crystalline polyethylene-block-poly(ethylene oxide) (PE-PEO) diblock copolymer with poly(hydroxyether of bisphenol A) (PH) were investigated by differential scanning calorimetry, transmission electron microscopy and small-angle X-ray scattering. The symmetric PE-PEO diblock copolymer consists of a PH-miscible PEO block and a PH-immiscible PE block. However, PH only exhibits partial miscibility with the PEO block of the copolymer in the PH/PE-PEO blends; both macrophase and microphase separations took place. There existed two macrophases in the PH/PE-PEO blends, i.e., a PH-rich phase and a PE-PEO copolymer-rich phase. The PE block of the copolymer in the blends exhibited fractionated crystallization behavior by homogeneous nucleation. There appeared three crystallization exotherms related to the crystallization of the PE block within three different microenvironments in the PH/PE-PEO blends

  10. Morphological and nanomechanical behavior of supported lipid bilayers on addition of cationic surfactants.

    Science.gov (United States)

    Lima, Lia M C; Giannotti, Marina I; Redondo-Morata, Lorena; Vale, M Luísa C; Marques, Eduardo F; Sanz, Fausto

    2013-07-30

    The addition of surfactants to lipid bilayers is important for the modulation of lipid bilayer properties (e.g., in protein reconstitution and development of nonviral gene delivery vehicles) and to provide insight on the properties of natural biomembranes. In this work, the thermal behavior, organization, and nanomechanical stability of model cationic lipid-surfactant bilayers have been investigated. Two different cationic surfactants, hexadecyltrimethylammonium bromide (CTAB) and a novel derivative of the amino acid serine (Ser16TFAc), have been added (up to 50 mol %) to both liposomes and supported lipid bilayers (SLBs) composed by the zwitterionic phospholipid DPPC. The thermal phase behavior of mixed liposomes has been probed by differential scanning calorimetry (DSC), and the morphology and nanomechanical properties of mixed SLBs by atomic force microscopy-based force spectroscopy (AFM-FS). Although DSC thermograms show different results for the two mixed liposomes, when both are deposited on mica substrates similar trends on the morphology and the mechanical response of the lipid-surfactant bilayers are observed. DSC thermograms indicate microdomain formation in both systems, but while CTAB decreases the degree of organization on the liposome bilayer, Ser16TFAc ultimately induces the opposite effect. Regarding the AFM-FS studies, they show that microphase segregation occurs for these systems and that the effect is dependent on the surfactant content. In both SLB systems, different microdomains characterized by their height and breakthrough force Fb are formed. The molecular organization and composition is critically discussed in the light of our experimental results and literature data on similar lipid-surfactant systems. PMID:23782267

  11. Tailoring polyacrylonitrile interfacial morphological structure by crystallization in the presence of single-wall carbon nanotubes.

    Science.gov (United States)

    Zhang, Yiying; Song, Kenan; Meng, Jiangsha; Minus, Marilyn L

    2013-02-01

    In order to improve stress transfer between polymer matrixes and nanofillers, controlling the structure development in the interphase region during composite processing is a necessity. For polyacrylonitrile (PAN)/single-wall carbon nanotubes (SWNT) composites, the formation of the PAN interphase in the presence of the SWNT as a function of processing conditions is studied. Under these conditions, three distinct interfacial coating morphologies of PAN are observed on SWNT. In the semidilute polymer concentration regime subjected to shearing, PAN extended-chain tubular coatings are formed on SWNT. Dilute PAN/SWNT quiescent solutions subjected to cooling yields hybrid periodic shish-kebab structures (first observation for PAN polymer), and dilute PAN/SWNT quiescent solutions subjected to rapid cooling results in the formation of an irregular PAN crystalline coating on the SWNT. PMID:23286387

  12. Evaluation of Front Morphological Development of Reactive Solute Transport Using Behavior Diagrams

    Directory of Open Access Journals (Sweden)

    Jui-Sheng Chen

    2009-01-01

    Full Text Available While flowing through porous medium, ground water flow dissolves minerals thereby in creasing medium porosity and ultimately permeability. Reactive fluid flows preferentially into highly permeable zones, which are therefore dissolved most rapidly, producing a further preferential permeability enhancement. Accordingly, slight non-uniformities present in porous medium can be amplified and lead to fingering reaction fronts. The objective of this study is to investigate dissolution-induced porosity changes on reaction front morphology in homogeneous porous medium with two non-uniformities. Four controlling parameters, including up stream pressure gradient, reaction rate constant, non-uniformities spacing and non-uniformity strength ratio are comprehensively considered. By using a modified version of the numerical code, NSPCRT, to conduct a series of numerical simulations, front behavior diagrams are constructed to illustrate the morphologies of reaction fronts under various combinations of these four factors. Simulation results indicate that the two non-uniformities are inhibited into a planar front under low up stream pressure gradient, merge into a single-fingering front under inter mediate up stream pressure gradient, or grow into a double-fingers front under high up stream pressure gradient. More over, the two non-uniformities tend to develop intoadouble-fingering front as the non-uniformity strength ratio in creases from 0.2 to 1.0, and merge into a single-fingering front while the non-uniformity strength ratio in creases from 1.0 to 1.8. When the reaction rate constant is small, the two non-uniformities merge into a single front. Reaction rate constant significantly affects front advancing velocity. The front advancing velocity decreases with the reaction rate constant. Based on these results, front behavior diagrams which de fine the morphologies of the reaction fronts for these four parameters are constructed. Moreover, non

  13. Morphological appearances and photo-controllable coloration of dye-doped cholesteric liquid crystal/polymer coaxial microfibers fabricated by coaxial electrospinning technique.

    Science.gov (United States)

    Lin, Jia-De; Chen, Che-Pei; Chen, Lin-Jer; Chuang, Yu-Chou; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-02-01

    This study systematically investigates the morphological appearance of azo-chiral dye-doped cholesteric liquid crystal (DDCLC)/polymer coaxial microfibers obtained through the coaxial electrospinning technique and examines, for the first time, their photocontrollable reflection characteristics. Experimental results show that the quasi-continuous electrospun microfibers can be successfully fabricated at a high polymer concentration of 17.5 wt% and an optimum ratio of 2 for the feeding rates of sheath to core materials at 25 °C and a high humidity of 50% ± 2% in the spinning chamber. Furthermore, the optical controllability of the reflective features for the electrospun fibers is studied in detail by changing the concentration of the azo-chiral dopant in the core material, the UV irradiation intensity, and the core diameter of the fibers. Relevant mechanisms are addressed to explain the optical-control behaviors of the DDCLC coaxial fibers. Considering the results, optically controllable DDCLC coaxial microfibers present potential applications in UV microsensors and wearable smart textiles or swabs. PMID:26906876

  14. Locomotor behavior and long bone morphology in individual free-ranging chimpanzees.

    Science.gov (United States)

    Carlson, Kristian J; Doran-Sheehy, Diane M; Hunt, Kevin D; Nishida, Toshisada; Yamanaka, Atsushi; Boesch, Christophe

    2006-04-01

    We combine structural limb data and behavioral data for free-ranging chimpanzees from Taï (Ivory Coast) and Mahale National Parks (Tanzania) to begin to consider the relationship between individual variation in locomotor activity and morphology. Femoral and humeral cross sections of ten individuals were acquired via computed tomography. Locomotor profiles of seven individuals were constructed from 3387 instantaneous time-point observations (87.4 hours). Within the limited number of suitable chimpanzees, individual variation in locomotor profiles displayed neither clear nor consistent trends with diaphyseal cross-sectional shapes. The percentages of specific locomotor modes did not relate well to diaphyseal shapes since neither infrequent nor frequent locomotor modes varied consistently with shapes. The percentage of arboreal locomotion, rather than estimated body mass, apparently had comparatively greater biological relevance to variation in diaphyseal shape. The mechanical consequences of locomotor modes on femoral and humeral diaphyseal shapes (e.g., orientation of bending strains) may overlap between naturalistic modes more than currently is recognized. Alternatively, diaphyseal shape may be unresponsive to mechanical demands of these specific locomotor modes. More data are needed in order to discern between these possibilities. Increasing the sample to include additional free-ranging chimpanzees, or primates in general, as well as devoting more attention to the mechanics of a greater variety of naturalistic locomotor modes would be fruitful to understanding the behavioral basis of diaphyseal shapes. PMID:16376413

  15. 牛乳清结晶条件的探索及其结晶体形貌%Exploration of Bovine Whey Crystallization Conditions and Morphology of Proteins Crystals

    Institute of Scientific and Technical Information of China (English)

    俞越钱

    2016-01-01

    以脱脂及去酪蛋白的牛乳清为原料,利用紫外分光光度法及SDS-PAGE电泳技术,在pH 4.7~8.0,NaCl浓度0.5~2.0 mol/L 条件下,对其结晶情况进行了研究。结果表明:牛乳清蛋白中的免疫球蛋白G(IgG)是一种理想的目标蛋白,而pH 7.0则是得到IgG的理想pH。最后还利用了工业相机及荧光倒置显微镜对牛乳清结晶体进行了拍摄,发现其中主要有长方晶、四角晶、菱方晶三种结晶体形貌。%With UV spectrophotometry and electrophoresis, degreased bovine whey after removal of ca-sein was studied in conditions of pH 4.7~8.0 and 0.5~2.0 mol/L NaCl. The results showed that immunoglob-ulin (IgG) was a kind of ideal target protein in bovine whey. Meanwhile, pH 7.0 was the ideal pH to obtain IgG. Finally, the crystallization behavior of whey was surveyed by an inverted fluorescence microscope and a high resolution digital camera. Furthermore, three kinds of morphology including orthorhombic, tetragonal and rhombus crystals were observed.

  16. Optical diode behavior of photonic crystal structure with asymmetric Kerr defect

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Optical diode behavior of asymmetric one-dimensional photonic crystal with Kerr defect is numerically investigated using nonlinear transfer matrix method. In the linear case, the intensity and the phase of transmitted field are the same for the forward and backward operations. In the nonlinear case, however, the transmitted intensities are much different for the two operations, which display diode characteristic. Physical origin of the anisotropic transmission lies in the different localizations in the defect layer of the two operations.

  17. Frequency Behavior of a Quartz Crystal Microbalance (Qcm in Contact with Selected Solutions

    Directory of Open Access Journals (Sweden)

    Z. A. Talib

    2006-01-01

    Full Text Available A device was constructed to monitor viscosity of solutions using fundamental frequency of 9 MHz and 10 MHz quartz crystal. Piezoelectric quartz crystals with gold electrodes were mounted by O-ring in between liquid flow cell. Only one side of the crystal was exposed to the solutions which were pumped through silicon tube by a peristaltic pump. The measured frequency shift was observed in order to investigate the interfacial behavior of some selected solution in contact with one surface of Quartz Crystal Microbalance (QCM. An analysis of the interaction between an AT-cut quartz crystal microbalance and various liquid system of analytical interest is presented. The analysis which includes piezoelectric effects and other influences; liquid properties, experimental conditions and the characteristic of the solution are reported. Oscillation in distilled water is taken as a reference. The frequency change caused by the density (ρ, gcm-3 and viscosity (η gcm-1s-1 were found to be proportional to the square root of the product, (ρ η. The result suggested that analysis of small frequency shifts during EQCM studies needs to account for changes in ρ and η of the solution. Generally, all the liquid tested showed an increment of the frequency shift with increasing content of solutes. For each solution, the frequency was recorded as the concentration increases from distilled water to a very concentrated solution. The frequency measurements carried out for saccharide solution produces the maximum changes of frequency shift compared with other solutions.

  18. Effects of emulsifier addition on the crystallization and melting behavior of palm olein and coconut oil.

    Science.gov (United States)

    Maruyama, Jessica Mayumi; Soares, Fabiana Andreia Schafer De Martini; D'Agostinho, Natalia Roque; Gonçalves, Maria Inês Almeida; Gioielli, Luiz Antonio; da Silva, Roberta Claro

    2014-03-12

    Two commercial emulsifiers (EM1 and EM2), containing predominantly monoacylglycerols (MAGs), were added in proportiond of 1.0 and 3.0% (w/w) to coconut oil and palm olein. EM1 consisted of approximately 90% MAGs, whereas EM2 consisted of approximately 50% MAGs. The crystallization behavior of these systems was evaluated by differential scanning calorimetry (DSC) and microscopy under polarized light. On the basis of DSC results, it was clear that the addition of EM2 accelerated the crystallization of coconut oil and delayed the crystallization of palm olein. In both oils EM2 addition led to the formation of smaller spherulites, and these effects improved the possibilities for using these fats as ingredients. In coconut oil the spherulites were maintained even at higher temperatures (20 °C). The addition of EM1 to coconut oil changed the crystallization pattern. In palm olein, the addition of 3.0% (w/w) of this emulsifier altered the pattern of crystallization of this fat.

  19. Morphology Change of C60 Islands on Organic Crystals Observed by Atomic Force Microscopy.

    Science.gov (United States)

    Freund, Sara; Hinaut, Antoine; Pawlak, Rémy; Liu, Shi-Xia; Decurtins, Silvio; Meyer, Ernst; Glatzel, Thilo

    2016-06-28

    Organic-organic heterojunctions are nowadays highly regarded materials for light-emitting diodes, field-effect transistors, and photovoltaic cells with the prospect of designing low-cost, flexible, and efficient electronic devices.1-3 However, the key parameter of optimized heterojunctions relies on the choice of the molecular compounds as well as on the morphology of the organic-organic interface,4 which thus requires fundamental studies. In this work, we investigated the deposition of C60 molecules at room temperature on an organic layer compound, the salt bis(benzylammonium)bis(oxalato)cupurate(II), by means of noncontact atomic force microscopy. Three-dimensional molecular islands of C60 having either triangular or hexagonal shapes are formed on the substrate following a "Volmer-Weber" type of growth. We demonstrate the dynamical reshaping of those C60 nanostructures under the local action of the AFM tip at room temperature. The dissipated energy is about 75 meV and can be interpreted as the activation energy required for this migration process.

  20. Magnetostrictive behaviors of Fe-Al(001 single-crystal films under rotating magnetic fields

    Directory of Open Access Journals (Sweden)

    Tetsuroh Kawai

    2016-05-01

    Full Text Available Magnetostrictive behaviors of Fe100−x − Alx(x = 0 − 30 at.%(001 single-crystal films under rotating magnetic fields are investigated along the two different crystallographic orientations, [100] and [110]. The behaviors of Fe and Fe90Al10 films show bath-tub like waveform along [100], easy magnetization axis, and triangular waveform along [110], hard magnetization axis, with respect to their four-fold magnetic anisotropy. On the other hand, the behaviors of Fe80Al20 film are different from those of Fe or Fe90Al10 film. The output of the film along [100] shows a strong magnetic field dependence. The Fe70Al30 film shows similar magnetostrictive behaviors along both [100] and [110] reflecting its magnetic properties, which are almost same for the both directions. The growth of ordered phase (B2 in Fe80Al20 and Fe70Al30 films is considered to have affected their magnetostrictive behaviors. The Al content dependence on λ100 and λ111 values shows similar tendency to that reported for the bulk samples but the values are slightly different. The Fe90Al10(001 single-crystal film shows a large magnetostriction along [100] under a very small magnetic field of 0.02 kOe, which is comparable to the saturated one, and changes the value abruptly in relation to the angle of applied magnetic field.

  1. Characterizing newly repopulated microglia in the adult mouse: impacts on animal behavior, cell morphology, and neuroinflammation.

    Directory of Open Access Journals (Sweden)

    Monica R P Elmore

    Full Text Available Microglia are the primary immune cell in the brain and are postulated to play important roles outside of immunity. Administration of the dual colony-stimulating factor 1 receptor (CSF1R/c-Kit kinase inhibitor, PLX3397, to adult mice results in the elimination of ~99% of microglia, which remain eliminated for as long as treatment continues. Upon removal of the inhibitor, microglia rapidly repopulate the entire adult brain, stemming from a central nervous system (CNS resident progenitor cell. Using this method of microglial elimination and repopulation, the role of microglia in both healthy and diseased states can be explored. Here, we examine the responsiveness of newly repopulated microglia to an inflammatory stimulus, as well as determine the impact of these cells on behavior, cognition, and neuroinflammation. Two month-old wild-type mice were placed on either control or PLX3397 diet for 21 d to eliminate microglia. PLX3397 diet was then removed in a subset of animals to allow microglia to repopulate and behavioral testing conducted beginning at 14 d repopulation. Finally, inflammatory profiling of the microglia-repopulated brain in response to lipopolysaccharide (LPS; 0.25 mg/kg or phosphate buffered saline (PBS was determined 21 d after inhibitor removal using quantitative real time polymerase chain reaction (RT-PCR, as well as detailed analyses of microglial morphologies. We find mice with repopulated microglia to perform similarly to controls by measures of behavior, cognition, and motor function. Compared to control/resident microglia, repopulated microglia had larger cell bodies and less complex branching in their processes, which resolved over time after inhibitor removal. Inflammatory profiling revealed that the mRNA gene expression of repopulated microglia was similar to normal resident microglia and that these new cells appear functional and responsive to LPS. Overall, these data demonstrate that newly repopulated microglia function

  2. Characterizing newly repopulated microglia in the adult mouse: impacts on animal behavior, cell morphology, and neuroinflammation.

    Science.gov (United States)

    Elmore, Monica R P; Lee, Rafael J; West, Brian L; Green, Kim N

    2015-01-01

    Microglia are the primary immune cell in the brain and are postulated to play important roles outside of immunity. Administration of the dual colony-stimulating factor 1 receptor (CSF1R)/c-Kit kinase inhibitor, PLX3397, to adult mice results in the elimination of ~99% of microglia, which remain eliminated for as long as treatment continues. Upon removal of the inhibitor, microglia rapidly repopulate the entire adult brain, stemming from a central nervous system (CNS) resident progenitor cell. Using this method of microglial elimination and repopulation, the role of microglia in both healthy and diseased states can be explored. Here, we examine the responsiveness of newly repopulated microglia to an inflammatory stimulus, as well as determine the impact of these cells on behavior, cognition, and neuroinflammation. Two month-old wild-type mice were placed on either control or PLX3397 diet for 21 d to eliminate microglia. PLX3397 diet was then removed in a subset of animals to allow microglia to repopulate and behavioral testing conducted beginning at 14 d repopulation. Finally, inflammatory profiling of the microglia-repopulated brain in response to lipopolysaccharide (LPS; 0.25 mg/kg) or phosphate buffered saline (PBS) was determined 21 d after inhibitor removal using quantitative real time polymerase chain reaction (RT-PCR), as well as detailed analyses of microglial morphologies. We find mice with repopulated microglia to perform similarly to controls by measures of behavior, cognition, and motor function. Compared to control/resident microglia, repopulated microglia had larger cell bodies and less complex branching in their processes, which resolved over time after inhibitor removal. Inflammatory profiling revealed that the mRNA gene expression of repopulated microglia was similar to normal resident microglia and that these new cells appear functional and responsive to LPS. Overall, these data demonstrate that newly repopulated microglia function similarly to the

  3. Molecular adsorption on ZnO(1010) single-crystal surfaces: morphology and charge transfer.

    Science.gov (United States)

    Chen, Jixin; Ruther, Rose E; Tan, Yizheng; Bishop, Lee M; Hamers, Robert J

    2012-07-17

    While ZnO has excellent electrical properties, it has not been widely used for dye-sensitized solar cells, in part because ZnO is chemically less stable than widely used TiO(2). The functional groups typically used for surface passivation and for attaching dye molecules either bind weakly or etch the ZnO surface. We have compared the formation of molecular layers from alkane molecules with terminal carboxylic acid, alcohol, amine, phosphonic acid, or thiol functional groups on single-crystal zinc oxide (1010) surfaces. Atomic force microscopy (AFM) images show that alkyl carboxylic acids etch the surface whereas alkyl amine and alkyl alcohols bind only weakly on the ZnO(1010) surface. Phosphonic acid-terminated molecules were found to bind to the surface in a heterogeneous manner, forming clusters of molecules. Alkanethiols were found to bind to the surface, forming highly uniform monolayers with some etching detected after long immersion times in an alkanethiol solution. Monolayers of hexadecylphosphonic acid and octadecanethiol were further analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. AFM scratching shows that thiols were bound strongly to the ZnO surface, suggesting the formation of strong Zn-S covalent bonds. Surprisingly, the tridentate phosphonic acids adhered much more weakly than the monodentate thiol. The influence of organic grafting on the charge transfer to ZnO was studied by time-resolved surface photovoltage measurements and electrochemical impedance measurements. Our results show that the grafting of thiols to ZnO leads to robust surfaces and reduces the surface band bending due to midgap surface states.

  4. Morphologies of solid-liquid interface and surface steps during rapid growth of BaB2O4 single crystals

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The evolution of solid-liquid interface during BBO single crystal growth was stud- ied by the differential interference microscopy. And the step morphology on (0001) surface of the as-grown crystal was observed by the atomic force microscopy as well. It was found that the transition from a flat solid-liquid interface to a skeletal shape will occur in case of rapid growth. However, AFM images of surface steps revealed morphology differences correlated with crystallographic directions. The steps advancing along <1010 > direction form the step flow, whereas those steps propagating along <0110 > direction shape into step segments. Measurements of step heights by AFM indicated that it is the high anisotropy of the dimension of growth unit and step bunching due to the enlargement of concentration difference along the surface that results in the anisotropy of step morphologies.

  5. Morphologies of solid-liquid interface and surface steps during rapid growth of BaB2O4 single crystals

    Institute of Scientific and Technical Information of China (English)

    PAN XiuHong; AI Fei; JIN WeiQing; LIU Yan; ZHANG Ying

    2007-01-01

    The evolution of solid-liquid interface during BBO single crystal growth was studied by the differential interference microscopy. And the step morphology on (0001) surface of the as-grown crystal was observed by the atomic force microscopy as well. It was found that the transition from a flat solid-liquid interface to a skeletal shape will occur in case of rapid growth. However, AFM images of surface steps revealed morphology differences correlated with crystallographic directions. The steps advancing along direction form the step flow, whereas those steps propagating along direction shape into step segments. Measurements of step heights by AFM indicated that it is the high anisotropy of the dimension of growth unit and step bunching due to the enlargement of concentration difference along the surface that results in the anisotropy of step morphologies.

  6. Relationship between crystallization behavior, microstructure, and macroscopic properties in trans containing and trans free coating fats and coatings.

    Science.gov (United States)

    Foubert, Imogen; Vereecken, Jeroen; Smith, Kevin W; Dewettinck, Koen

    2006-09-20

    The objective of this study is to gain further understanding into the relationship between crystallization behavior, microstructure, and macroscopic properties in coating fats. The isothermal crystallization behavior of two coating fats (one trans containing and one trans free) was examined, both as pure fats and in coatings, by DSC and microscopy. Furthermore, the hardness of the samples was examined after cooling in a water bath at two different temperatures and at three different storage times. Both fats seemed to show an alpha-mediated beta' crystallization at lower temperatures and a direct beta' crystallization at higher temperatures. The trans free coating fat clearly crystallized faster and in smaller crystals. The hardness was governed not only by the amount of solid fat present in the network but also by the structure of this network. The coating matrix components seem to have a pronounced influence on the microstructure and thus on the macroscopic properties. PMID:16968091

  7. Effect of surface treatment of titanium dioxide nanoparticles on non-isothermal crystallization behavior, viscoelastic transitions and cold crystallization of poly(ethylene terephthalate) nanocomposites

    OpenAIRE

    Cayuela Marín, Diana; Cot Valle, María Ana; Riva Juan, Mª del Carmen; Sanchez Leija, Regina Janete; Sanchez Loredo, Maria Guadalupe; Algaba Joaquín, Inés María; Manich Bou, Albert M.

    2014-01-01

    The effect of untreated and tri-n-octylphosphine oxide (TOPO) surface-treated TiO2 nanoparticles when included as filler in poly (ethylene terephthalate) on its compatibility, non-isothermal crystallization behavior, viscoelastic transitions and cold crystallization has been studied. The effectiveness of the surface treatment has been studied using infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA). The effect of the untreated and surface-treated nanofiller content in the ...

  8. A Simulation Study on the Effects of Dendritic Morphology on Layer V Prefontal Pyramidal Cell Firing Behavior

    Directory of Open Access Journals (Sweden)

    Maria ePsarrou

    2014-09-01

    Full Text Available Pyramidal cells, the most abundant neurons in neocortex, exhibit significant structural variability across different brain areas and layers in different species. Moreover, in response to a somatic step current, these cells display a range of firing behaviors, the most common being (1 repetitive action potentials (Regular Spiking - RS, and (2 an initial cluster of 2-5 action potentials with short ISIs followed by single spikes (Intrinsic Bursting - IB. A correlation between firing behavior and dendritic morphology has recently been reported. In this work we use computational modeling to investigate quantitatively the effects of the basal dendritic tree morphology on the firing behavior of 112 three-dimensional reconstructions of layer V PFC rat pyramidal cells. Particularly, we focus on how different morphological (diameter, total length, volume and branch number and passive (Mean Electrotonic Path length features of basal dendritic trees shape somatic firing when the spatial distribution of ionic mechanisms in the basal dendritic trees is uniform or non-uniform. Our results suggest that total length, volume and branch number are the best morphological parameters to discriminate the cells as RS or IB, regardless of the distribution of ionic mechanisms in basal trees. The discriminatory power of total length, volume and branch number remains high in the presence of different apical dendrites. These results suggest that morphological variations in the basal dendritic trees of layer V pyramidal neurons in the PFC influence their firing patterns in a predictive manner and may in turn influence the information processing capabilities of these neurons.

  9. Sexual conflict predicts morphology and behavior in two species of penduline tits

    Directory of Open Access Journals (Sweden)

    Komdeur Jan

    2010-04-01

    Full Text Available Abstract Background The evolutionary interests of males and females rarely coincide (sexual conflict, and these conflicting interests influence morphology, behavior and speciation in various organisms. We examined consequences of variation in sexual conflict in two closely-related passerine birds with contrasting breeding systems: the Eurasian penduline tit Remiz pendulinus (EPT exhibiting a highly polygamous breeding system with sexually antagonistic interests over parental care, and the socially monogamous Cape penduline tit Anthoscopus minutus (CPT. We derived four a priori predictions from sexual conflict theory and tested these using data collected in Central Europe (EPT and South Africa (CPT. Firstly, we predicted that EPTs exhibit more sexually dimorphic plumage than CPTs due to more intense sexual selection. Secondly, we expected brighter EPT males to provide less care than duller males. Thirdly, since song is a sexually selected trait in many birds, male EPTs were expected to exhibit more complex songs than CPT males. Finally, intense sexual conflict in EPT was expected to lead to low nest attendance as an indication of sexually antagonistic interests, whereas we expected more cooperation between parents in CPT consistent with their socially monogamous breeding system. Results Consistent with our predictions EPTs exhibited greater sexual dimorphism in plumage and more complex song than CPTs, and brighter EPT males provided less care than duller ones. EPT parents attended the nest less frequently and less simultaneously than CPT parents. Conclusions These results are consistent with sexual conflict theory: species in which sexual conflict is more manifested (EPT exhibited a stronger sexual dimorphism and more elaborated sexually selected traits than species with less intense sexual conflict (CPT. Our results are also consistent with the notion that EPTs attempt to force their partner to work harder as expected under sexual conflict: each

  10. Classification and correlation of miocene tuffs in the Kanto area using zircon crystal morphology. Zircon no kessho keitai ni yoru Kanto chiho no chushinseigyokaigan no bunrui to taihi

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, M. (Geological Survey of Japan, Tsukuba (Japan)); Hayashi, M. (Kyushu University, Fukuoka (Japan). Geothermal Research Center)

    1991-06-16

    Samples were collected from Miocene tuffs widely distributed on Takasaki area, Iwatono Hill, and Karasuyama area in the Kanto district. Zircon crystals were separated from seven samples in them, and the crystal morphology was investigated. Seven samples can be divided into two groups, one is characterized by zircon crystals of the 100 dominant type and short prismatic, and Kt-1 (Kitamura Tuff), I-8 (Shogunzawa Tuff) and Og-1 belong to this group. The other group is characterized by zircon crystals of the intermediate type and prismatic, and Bb-1 (Baba Tuff), I-12 (Okuda Tuff), Og-25 and Og-52 (Iwako Tuff Member) belong to this group. Other data, including micro fossils and radiometric ages, support the above division. The quantitative description is reliable as one of the standard criteria for the geologic correlation of tuff layers over a wide area. 33 refs., 4 figs., 1 tab.

  11. Thermal and morphological behavior of chitosan/PEO blends containing gold nanoparticles. Experimental and theoretical studies.

    Science.gov (United States)

    Bonardd, Sebastián; Schmidt, Mathias; Saavedra-Torres, Mario; Leiva, Angel; Radic, Deodato; Saldías, César

    2016-06-25

    Using solution-casting method, binary blends of chitosan (CS) and poly (ethylene oxide) (PEO 100,000) containing Au nanoparticles (AuNPs) were prepared. Shifts in the melting temperature (Tm) and crystallization temperature (Tc) values for CS/PEO and CS/PEO/AuNPs blends were observed by calorimetric analysis. In general, CS/PEO/AuNPs blends tended to decompose at higher temperatures than neat polymers. From the FT-IR spectra, shifts in the main signals, such as -NH2, -OH and COC, were detected in the blends and were attributed to the polymer interactions and the incorporation of gold nanoparticles. In addition, the analysis of the blend topographies by atomic force microscopy (AFM) showed that at a higher CS content, more homogenous surfaces were observed. This behavior was attributed to the interactions present in the CS/PEO/AuNPs blends. Finally, theoretical analyses helped to confirm that the gold nanoparticles would be preferentially adsorbed onto the chitosan microdomains due to the interactions between acetyl and hydroxyl groups and Au atoms. PMID:27083823

  12. Influence of stress, temperature and crystal morphology on isothermal densification and specific surface area decrease of new snow

    Science.gov (United States)

    Schleef, S.; Löwe, H.; Schneebeli, M.

    2014-10-01

    Laboratory-based, experimental data for the microstructural evolution of new snow are scarce, though applications would benefit from a quantitative characterization of the main influences. To this end, we have analyzed the metamorphism and concurrent densification of new snow under isothermal conditions by means of X-ray microtomography and compiled a comprehensive data set of 45 time series. In contrast to previous measurements on isothermal metamorphism on time scales of weeks to months, we analyzed the initial 24-48 h of snow evolution at a high temporal resolution of 3 hours. The data set comprised natural and laboratory-grown snow, and experimental conditions included systematic variations of overburden stress, temperature and crystal habit to address the main influences on specific surface area (SSA) decrease rate and densification rate in a snowpack. For all conditions, we found a linear relation between density and SSA, indicating that metamorphism has an immediate influence for the densification of new snow. The slope of the linear relation, however, depends on the other parameters which were analyzed individually to derive a best-fit parameterization for the SSA decrease rate and densification rate. In the investigated parameter range, we found that the initial value of the SSA constituted the main morphological influence on the SSA decrease rate. In turn, the SSA decrease rate constituted the main influence on the densification rate.

  13. Effect of anodic oxide films on low temperature mechanical behavior of niobium single crystals

    International Nuclear Information System (INIS)

    The effect of thin (less than or equal to 1500 A) anodic oxide films on the mechanical behavior of single crystals of niobium at low temperatures (T less than or equal to 0.15 T/sub M/) was investigated. Oxide films affect mechanical behavior in two ways: the yield stress is reduced and the stress-strain curves are serrated over an appreciable range of strains. When oxide-coated specimens are also prestrained into stage I at 3000K, the serrations observed at low temperatures disappear, the flow stress is further reduced, the ductility is increased, and a three-stage work hardening behavior occurs. A model involving generation and motion of nonscrew dislocations from the oxide-metal interface is used to explain the results

  14. A Study of Hardening Behavior Based on a Finite-Deformation Gradient Crystal-Plasticity Model

    CERN Document Server

    Pouriayevali, Habib

    2016-01-01

    A systematic study on the different roles of the governing components of a well-defined finite-deformation gradient crystal-plasticity model proposed by (Gurtin, 2008b) is carried out, in order to visualize the capability of the model in the prediction of a wide range of hardening behaviors as well as rate-dependent, scale-variation and Bauschinger-like responses in a single crystal. A function of accumulation rates of dislocations is employed and viewed as a measure of formation of short-range interactions which impede dislocation movements within a crystal. The model is first represented in the reference configuration for the purpose of numerical implementation, and then implemented in the FEM software ABAQUS via a user-defined subroutine (UEL). Our simulation results reveal that the dissipative gradient-strengthening is also identified as a source of isotropic-hardening behavior, which represents the effect of cold work introduced by (Gurtin and Ohno, 2011). Moreover, plastic flows in predefined slip syste...

  15. Sexual selection and the evolution of behavior, morphology, neuroanatomy and genes in humans and other primates.

    Science.gov (United States)

    Stanyon, Roscoe; Bigoni, Francesca

    2014-10-14

    Explaining human evolution means developing hypotheses about the occurrence of sex differences in the brain. Neuroanatomy is significantly influenced by sexual selection, involving the cognitive domain through competition for mates and mate choice. Male neuroanatomy emphasizes subcortical brain areas and visual-spatial skills whereas that of females emphasizes the neocortex and social cognitive areas. In primate species with high degrees of male competition, areas of the brain dealing with aggression are emphasized. Females have higher mirror neuron activity scores than males. Hundreds of genes differ in expression profiles between males and females. Sexually selected differences in gene expression can produce neuroanatomical sex differences. A feedback system links genes, gene expression, hormones, morphology, social structure and behavior. Sex differences, often through female choice, can be rapidly modulated by socialization. Human evolution is a dramatic case of how a trend toward pair bonding and monogamy lowered male competition and increased female choice as a necessary step in releasing the cognitive potential of our species. PMID:25445181

  16. Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

  17. Synthesis and Liquid-Crystal Behavior of Bent Colloidal Silica Rods.

    Science.gov (United States)

    Yang, Yang; Chen, Guangdong; Martinez-Miranda, Luz J; Yu, Hua; Liu, Kun; Nie, Zhihong

    2016-01-13

    The design and assembly of novel colloidal particles are of both academic and technological interest. We developed a wet-chemical route to synthesize monodisperse bent rigid silica rods by controlled perturbation of emulsion-templated growth. The bending angle of the rods can be tuned in a range of 0-50° by varying the strength of perturbation in the reaction temperature or pH in the course of rod growth. The length of each arm of the bent rods can be individually controlled by adjusting the reaction time. For the first time we demonstrated that the bent silica rods resemble banana-shaped liquid-crystal molecules and assemble into ordered structures with a typical smectic B2 phase. The bent silica rods could serve as a visualizable mesoscopic model for exploiting the phase behaviors of bent molecules which represent a typical class of liquid-crystal molecules. PMID:26700616

  18. Influence of lignin on morphology, structure and thermal behavior of polylactic acid-based biocomposites

    Science.gov (United States)

    Canetti, Maurizio; Cacciamani, Adriana; Bertini, Fabio

    2016-05-01

    Polylactic acid (PLA) is a thermoplastic biodegradable polymer that can be made from annually renewable resources. Lignin is a natural amorphous polyphenolic macromolecule inexpensive and easily available. In the present study PLA and acetylated lignin biocomposites were prepared by casting from chloroform solution. PLA can crystallize from the melt in the α and α' forms, depending on the adopted crystallization conditions. The presence of the lignin in the biocomposites can interfere with the crystal formation process. Isothermal crystallizations were performed at different temperatures, the presence of lignin causes an increase of the time of crystallization, while the overall crystallization rate and the spherulite radial growth rate decrease with enhancing the lignin content in the biocomposites.

  19. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate

    Science.gov (United States)

    Yamaguchi, Akihiro; Smith, Gregory; Yi, Youngwoo; Xu, Charles; Biffi, Silvia; Serra, Francesca; Bellini, Tommaso; Clark, Noel

    2014-03-01

    Chromonic liquid crystals (CLCs) are formed when planar molecules dissolved in water stack into rod-like aggregates that can order as liquid crystals. Isotropic, nematic, and M-phases can be observed depending on the degree of molecular orientational and positional order by variation of the CLC concentration. We focused on mixtures of two well-known CLCs, Sunset Yellow, a food dye, and disodium cromoglycate (DSCG), an asthma medication. In order to study the phase behaviors of these mixtures, we observed their textures in glass cells and capillaries using polarized light microscopy. We report here a ternary phase diagram describing the complete phase behavior of the CLC mixtures. We observed a variety of phase behaviors depending on species ratio and concentration. In the isotropic phase, no clear phase separation of the two dyes was observed, while separation did occur in many nematic and M-phase combinations. We will also describe phase observations made using a light spectroscopy and bulk centrifugal partitioning. Grant support: NSF DMR 1207606 and NSF MRSEC DMR-0820579.

  20. Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi; Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.jp

    2015-01-15

    Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths

  1. Synthesis, growth, morphology of the semiorganic nonlinear optical crystal L-glutamic acid hydrochloride and its structural, thermal and SHG characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Dhanasekaran, P.; Srinivasan, K. [Crystal Growth Laboratory, Department of Physics, School of Physical Sciences, Bharathiar University, Coimbatore-641 046, Tamil Nadu (India)

    2012-12-15

    One of the halide derivatives of L-glutamic acid which was identified as a semiorganic nonlinear optical material, L-glutamic acid hydrochloride [HOOC(CH{sub 2}){sub 2}CH(NH{sub 2})COOH.HCl], was grown as bulk single crystal and its significant properties were characterized. The stoichiometric title compound was synthesized and the solubility of its recrystallized form in DD water was determined in the temperature range 30-80 C by gravimetric method. Structural confirmation was carried out by powder X-ray diffraction study through lattice parameter verification. Optical quality smaller dimension single crystals were grown from aqueous solution by self nucleation through slow evaporation of solvent method and a large dimension single crystal was grown by slow cooling method with reversible seed rotation technique. Morphological importances of different growth facets of the as grown crystals were studied through optical goniometry. Unit cell structure of the grown crystal was refined by single crystal X-ray diffraction analysis, functional groups present in the crystal responsible for various modes of vibrations were confirmed by FTIR spectroscopy analysis, thermal stability of the grown crystal was analysed by TG/DTA and DSC and second harmonic generation (SHG) of a fundamental Nd:YAG laser beam by Kurtz technique. Results indicate that the grown crystal is in stoichiometric composition and has significant improvement in its thermal and SHG properties when compared to pure L-glutamic acid polymorphs. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Research on Mechanical Behaviors of Micro-crystal Muscovite/UHMWPE Composites to Impact Loading

    Directory of Open Access Journals (Sweden)

    Hu Huarong

    2016-01-01

    Full Text Available UHMWPE composites were prepared by hot pressing process with micro-crystal muscovite as reinforced particulates. The mechanical behaviors of composites to impact loading was evaluated by split Hopkinson bar. The results demonstrated that dynamic yield stress and failure stress of UHMWPE composites were gradually increased when the filling amount was less than 20%; when the filling content of muscovite was around 15%, the energy absorption efficiency of the composite reaches maximum value. It was also found that when strain rate within 3200/s, the dynamic yield stress, failure stress and energy absorption efficiency of UHMWPE composites increased with the increase of strain rate and display strain rate enhancement effect.

  3. Dielectric behavior of antiferroelectric liquid crystals in presence of flexoelectric effect

    Energy Technology Data Exchange (ETDEWEB)

    Das, Deblal; Mandal, Pravash; Majumder, Tapas Pal, E-mail: tpm@klyuniv.ac.in [Department of Physics, University of Kalyani, West Bengal (India)

    2015-06-15

    We studied theoretically the effect of flexoelectricity on the behavior of dielectric fluctuations of antiferroelectric liquid crystals (AFLCs) influenced by the mechanical distortion associated with flexoelectric effect. By using the appropriate free energy and the Landau-Ginzburg equation, we found an approximate expression of dielectric permittivity, which was strongly influenced by the existence of flexoelectric polarization for both in-phase and anti-phase motions. Consequently, the corresponding dielectric strength for both in-phase and anti-phase motions were varied due to the existence of flexoelectric polarization. (author)

  4. Dielectric Behavior of Antiferroelectric Liquid Crystals in Presence of Flexoelectric Effect

    Science.gov (United States)

    Das, Deblal; Mandal, Pravash; Pal Majumder, Tapas

    2015-06-01

    We studied theoretically the effect of flexoelectricity on the behavior of dielectric fluctuations of antiferroelectric liquid crystals (AFLCs) influenced by the mechanical distortion associated with flexoelectric effect. By using the appropriate free energy and the Landau-Ginzburg equation, we found an approximate expression of dielectric permittivity, which was strongly influenced by the existence of flexoelectric polarization for both in-phase and anti-phase motions. Consequently, the corresponding dielectric strength for both in-phase and anti-phase motions were varied due to the existence of flexoelectric polarization.

  5. Self-cleaning behavior in polyurethane/silica coatings via formation of a hierarchical packed morphology of nanoparticles

    Science.gov (United States)

    Hejazi, Iman; Mir Mohamad Sadeghi, Gity; Seyfi, Javad; Jafari, Seyed-Hassan; Khonakdar, Hossein Ali

    2016-04-01

    In the current research, a hierarchical morphology comprising of packed assembly of nanoparticles was induced in thermoplastic polyurethane (TPU)/silica nanocomposite coatings in order to achieve self-cleaning behavior. Moderately hydrophilic behavior of TPU hinders its transforming to a superhydrophobic material. In the presented method, a very thin layer of silica nanoparticles is applied to the surface of TPU sheets under elevated temperature and pressure. As temperature and pressure of the process remain unchanged, processing time was considered as a main variable. Based on scanning electron microscopy and confocal microscopy results, it was found that at a certain processing time, nanoparticles can form an utterly packed morphology leading to a self-cleaning behavior. Once the process was prolonged, TPU macromolecules found the chance to migrate onto the coating's top layer due to the enhanced mobility of chains at high temperature. This observation was further proved by X-ray photoelectron spectroscopy analysis and cross-sectional morphology. The presented method has promising potentials in transforming intrinsically hydrophilic polymers into superhydrophobic materials with self-cleaning behavior.

  6. Morphological and behavioral differences in the gastropod Trophon geversianus associated to distinct environmental conditions, as revealed by a multidisciplinary approach

    Science.gov (United States)

    Márquez, Federico; Nieto Vilela, Rocío Aimé; Lozada, Mariana; Bigatti, Gregorio

    2015-01-01

    The gastropod Trophon geversianus exhibits shell polymorphisms along its distribution in subtidal and intertidal habitats. Our hypothesis is that morphological and behavioral patterns of T. geversianus represent habitat-specific constrains; subsequently we expect an association between shell morphology, attachment behavior, and habitat. In order to test this hypothesis we compared individuals from intertidal and subtidal habitats, at three sites in Golfo Nuevo (Argentina). We analyzed shell morphology using classic morphometric variables, 3D geometric morphometrics and computing tomography scan. The results were complemented with field observations of attachment to substrate and turning time behavior, as well as of the number of shell scars produced by crab predation. Our results showed differences in shell size and shape between intertidal and subtidal-collected individuals. Centroid size, total weight and shell weight, as well as shell density and thickness were significantly lower in intertidal individuals than in subtidal ones. Gastropods from intertidal habitats presented a low-spired shell and an expanded aperture which might allow better attachment to the bottom substrate, while subtidal individuals presented a slender and narrower shell shape. The number of crab scars was significantly higher in shells from subtidal individuals. Observations of the behavior of gastropods placed at the intertidal splash zone showed 100% of attachment to the bottom in the intertidal individuals, while subtidal specimens only attached in average in 32% of the cases. These latter took 12 times longer to re-attach to the bottom when faced up. Phylogenetic analysis of COI gene fragments showed no consistent differences among individuals sampled in both habitats. All these results suggest that T. geversianus has developed two ecomorphs with distinct morphological and behavioral responses to physically stressful conditions registered in north Patagonian intertidals, as opposed to

  7. Acetyl-L-carnitine improves behavior and dendritic morphology in a mouse model of Rett syndrome.

    Directory of Open Access Journals (Sweden)

    Laura R Schaevitz

    Full Text Available Rett syndrome (RTT is a devastating neurodevelopmental disorder affecting 1 in 10,000 girls. Approximately 90% of cases are caused by spontaneous mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2. Girls with RTT suffer from severe motor, respiratory, cognitive and social abnormalities attributed to early deficits in synaptic connectivity which manifest in the adult as a myriad of physiological and anatomical abnormalities including, but not limited to, dimished dendritic complexity. Supplementation with acetyl-L-carnitine (ALC, an acetyl group donor, ameliorates motor and cognitive deficits in other disease models through a variety of mechanisms including altering patterns of histone acetylation resulting in changes in gene expression, and stimulating biosynthetic pathways such as acetylcholine. We hypothesized ALC treatment during critical periods in cortical development would promote normal synaptic maturation, and continuing treatment would improve behavioral deficits in the Mecp2(1lox mouse model of RTT. In this study, wildtype and Mecp2(1lox mutant mice received daily injections of ALC from birth until death (postnatal day 47. General health, motor, respiratory, and cognitive functions were assessed at several time points during symptom progression. ALC improved weight gain, grip strength, activity levels, prevented metabolic abnormalities and modestly improved cognitive function in Mecp2 null mice early in the course of treatment, but did not significantly improve motor or cognitive functions assessed later in life. ALC treatment from birth was associated with an almost complete rescue of hippocampal dendritic morphology abnormalities with no discernable side effects in the mutant mice. Therefore, ALC appears to be a promising therapeutic approach to treating early RTT symptoms and may be useful in combination with other therapies.

  8. Predator-induced behavioral and morphological plasticity in the tropical marine Gastropod Strombus gigas.

    Science.gov (United States)

    Delgado, Gabriel A; Glazer, Robert A; Stewart, Nicola J

    2002-08-01

    Florida queen conch stocks once supported a significant fishery, but overfishing prompted the state of Florida to institute a harvest moratorium in 1985. Despite the closure of the fishery, the queen conch population has been slow to recover. One method used in the efforts to restore the Florida conch population has been to release hatchery-reared juvenile conch into the wild; however, suboptimal predator avoidance responses and lighter shell weights relative to their wild counterparts have been implicated in the high mortality rates of released hatchery juveniles. We conducted a series of experiments in which hatchery-reared juvenile conch were exposed to a predator, the spiny lobster (Panulirus argus), to determine whether they could develop behavioral and morphological characteristics that would improve survival. Experiments were conducted in tanks with a calcareous sand substrate to simulate a natural environment. Conditioned conch were exposed to caged lobsters while conch in the control tanks were exposed to empty cages. Conditioned conch moved significantly less and buried themselves more frequently than the naive control conch. Morphometric data indicated that the conditioned conch grew at a significantly slower rate than the naive conch, but the shell weights of the two groups were not significantly different. This implies that the conditioned conch had thicker or denser shells than the control group. As a result, the conditioned conch had significantly higher survival than naive conch in a subsequent predation experiment in which a lobster was allowed to roam free in each tank for 24 hours. In the future, the conditioning protocols documented in this study will be used to increase the survival of hatchery-reared conch in the wild. PMID:12200261

  9. Morphological, behavioral and biological aspects of Azya luteipes Mulsant fed on Coccus viridis (Green

    Directory of Open Access Journals (Sweden)

    Juliana Nais

    2012-02-01

    Full Text Available One of the major pests of nursery seedlings of coffee (Coffea arabica L. is the green scale, Coccus viridis (Green (Hemiptera: Coccidae. The main predators of this species are beetles of the family Coccinellidae, especially Azya luteipes Mulsant. Morphological, behavioral and biological aspects of A. luteipes feeding on C. viridis on coffee plants were examined under laboratory conditions. Tests were conducted in room temperature at 28 ± 2 ºC. A. luteipes oviposits on the underside of the scale's body, laying two to four eggs per insect. The eggs have a subelliptical form and a white-clear color, and the incubation period is 8.3 ± 1.2 days. The number of eggs laid per female per day varies between eight and ten. A. luteipes undergoes four larval instars with durations of 2.0 ± 0, 3.2 ± 0.5, 3.6 ± 0.5 and 4.6 ± 0 days for the 1st, 2nd, 3rd and 4th instars, respectively. The average durations of the prepupal and pupal stages were 2.0 ± 0 and 10.9 ± 1.3 days, respectively. The viability of the larvae during each instar was 91.9, 89.3, 90.2 and 96.4 %, respectively, and the viabilities of prepupae and pupae were 99.1 and 98.2 %. The average duration of the egg-adult cycle was 34.3 ± 2.6 days, and the sex ratio was 0.52 %. Females presented a gray-colored head, while males presented a yellow head.

  10. Roles of morphology, anatomy, and aquaporins in determining contrasting hydraulic behavior of roots.

    Science.gov (United States)

    Bramley, Helen; Turner, Neil C; Turner, David W; Tyerman, Stephen D

    2009-05-01

    The contrasting hydraulic properties of wheat (Triticum aestivum), narrow-leafed lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus) roots were identified by integrating measurements of water flow across different structural levels of organization with anatomy and modeling. Anatomy played a major role in root hydraulics, influencing axial conductance (L(ax)) and the distribution of water uptake along the root, with a more localized role for aquaporins (AQPs). Lupin roots had greater L(ax) than wheat roots, due to greater xylem development. L(ax) and root hydraulic conductance (L(r)) were related to each other, such that both variables increased with distance from the root tip in lupin roots. L(ax) and L(r) were constant with distance from the tip in wheat roots. Despite these contrasting behaviors, the hydraulic conductivity of root cells (Lp(c)) was similar for all species and increased from the root surface toward the endodermis. Lp(c) was largely controlled by AQPs, as demonstrated by dramatic reductions in Lp(c) by the AQP blocker mercury. Modeling the root as a series of concentric, cylindrical membranes, and the inhibition of AQP activity at the root level, indicated that water flow in lupin roots occurred primarily through the apoplast, without crossing membranes and without the involvement of AQPs. In contrast, water flow across wheat roots crossed mercury-sensitive AQPs in the endodermis, which significantly influenced L(r). This study demonstrates the importance of examining root morphology and anatomy in assessing the role of AQPs in root hydraulics. PMID:19321713

  11. Effect of morphology of eutectic silicon crystals on mechanical properties and cleavage fracture toughness of AlSi5Cu1 alloy

    Directory of Open Access Journals (Sweden)

    M. Wierzbińska

    2005-12-01

    Full Text Available Purpose: The purpose of this paper is presentation of the results that concerned the influence of morphology of eutectic silicon crystals on mechanical properties, especially on the cleavage fracture toughness of AlSi5Cu1 alloy.Design/methodology/approach: Microscopic studies – optical microscope NIKON 300 and quantitative analysis of geometrical parameters of microstructure – image analysis program APHELION, tensile and fracture toughness tests – testing machine INSTRON 8810.Findings: The sizes of silicon crystals and values of yield strength, tensile strength and plane strain fracture toughness have been determined. Relationships between mechanical properties and silicon crystals size were described using Hall-Petch equation. It was found that a decrease in silicon crystals causes an increasing in strength and in fracture toughness.Practical implications: This paper is part of the previous author’s investigations which results in modification of the casting technology of turboblower compressor impellers.Originality/value: The microscopic observations indicated that alloy cracking begins with nucleation and growth of micro-cracks in the silicon crystals of large size, in orthogonal plane to tension direction. The hard and brittle silicon crystals are very strong barriers for slip in the stressed alloy.

  12. Thermomechanical fatigue behavior of coated and bare nickel-based superalloy single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chataigner, E.; Remy, L.

    1996-12-31

    The thermal-mechanical fatigue behavior of chromium-aluminum coated [001] single crystals of AM1, a nickel-base superalloy for turbine blades, is studied using a diamond shape cycle from 600 to 1,100 C. Comparison with bare specimens does not show any significant difference in thermal-mechanical fatigue nor in isothermal low cycle fatigue at high temperature. Metallographic observations on fracture surfaces and longitudinal sections of specimens tested to fatigue life or to a definite fraction of expected life have shown that the major crack tends to initiate from casting micropores in the sub-surface area very early in bare and coated specimens, under low cycle fatigue or thermal-mechanical fatigue. But the interaction between oxidation and fatigue cracking seems to play a major role. A simple model proposed by Reuchet and Remy has been identified for this single crystal superalloy. Its application to the life prediction under low cycle fatigue and thermal-mechanical fatigue for bare and coated single crystals with different orientations is shown.

  13. Crystal structure and thermal behavior of a new cadmium indium oxalate

    International Nuclear Information System (INIS)

    A new mixed metal oxalate Cd3In2(C2O4)6·9H2O, with an open-framework structure, has been prepared from a precipitation method at room temperature. Its crystal structure has been solved from single-crystal diffraction data. The compound crystallizes with space group P6422 and the cell parameters are a=8.566(5) A, c=37.811(5) A, V=2403(2) A3, and Z=3 (R1=0.036). The three-dimensional structure is built from three types of MO8 (M=Cd, In) polyhedra, i.e., triangular dodecahedra, bicapped trigonal prisms and an undefined distorted eight-fold cadmium polyhedron. Relationships with the structures of the related cadmium zirconium oxalates are discussed. The structure overview suggests the possibility to conceive new oxalate-based materials with open-framework structures. The thermal behavior of the new compound is described in details from temperature-dependent X-ray powder diffraction and thermogravimetry measurements. The dehydration process of the precursor is reversible in its stability temperature range. The final product consists of a mixture of nanocrystalline CdIn2O4 and the simple oxides

  14. Constitutive modeling of creep behavior in single crystal superalloys: Effects of rafting at high temperatures

    International Nuclear Information System (INIS)

    Rafting and creep modeling of single crystal superalloys at high temperatures are important for the safety assessment and life prediction in practice. In this research, a new model has been developed to describe the rafting evolution and incorporated into the Cailletaud single crystal plasticity model to simulate the creep behavior. The driving force of rafting is assumed to be the relaxation of the strain energy, and it is calculated with the local stress state, a superposition of the external and misfit stress tensors. In addition, the isotropic coarsening is introduced by the cube root dependence of the microstructure periodicity on creep time based on Ostwal ripening. Then the influence of rafting on creep deformation is taken into account as the Orowan stress in the single crystal plasticity model. The capability of the proposed model is validated with creep experiments of CMSX-4 at 950 °C and 1050 °C. It is able to predict the rafting direction at complex loading conditions and evaluate the channel width during rafting. For [001] tensile creep tests, good agreement has been shown between the model predictions and experimental results at different temperatures and stress levels. The creep acceleration can be captured with this model and is attributed to the microstructure degradation caused by the precipitate coarsening

  15. Crystallization and unusual rheological behavior in poly(ethylene oxide)–clay nanocomposites

    KAUST Repository

    Kelarakis, Antonios

    2011-05-01

    We report a systematic study of the crystallization and rheological behavior of poly(ethylene oxide) (PEO)-clay nanocomposites. To that end a series of nanocomposites based on PEOs of different molecular weight (103 < MW < 105 g/mol) and clay surface modifier was synthesized and characterized. Incorporation of organoclays with polar (MMT-OH) or aromatic groups (MMT-Ar) suppresses the crystallization of polymer chains in low MW PEO, but does not significantly affect the crystallization of high MW matrices. In addition, the relative complex viscosity of the nanocomposites based on low MW PEO increases significantly, but the effect is less pronounced at higher MWs. The viscosity increases in the series MMT-Alk < MMT-OH < MMT-Ar. In contrast to the neat PEO which exhibits a monotonic decrease of viscosity with temperature, all nanocomposites show an increase after a certain temperature. This is the first report of such dramatic enhancements in the viscoelasticity of nanocomposites, which are reversible, are based on a simple polymer matrix and are true in a wide temperature range. © 2011 Elsevier Ltd. All rights reserved.

  16. Effects of Polymeric Additives on the Crystallization and Release Behavior of Amorphous Ibuprofen

    Directory of Open Access Journals (Sweden)

    Su Yang Lee

    2013-01-01

    Full Text Available Some polymeric additives were studied to understand their effects on the amorphous phase of ibuprofen (IBU, used as a poorly water soluble pharmaceutical model compound. The amorphous IBU in bulk, as well as in nanopores (diameter ~24 nm of anodic aluminum oxide, was examined with the addition of poly(acrylic acid, poly(N-vinyl pyrrolidone, or poly(4-vinylphenol. Results of bulk crystallization showed that they were effective in limiting the crystal growth, while the nucleation of the crystalline phase in contact with water was nearly instantaneous in all cases. Poly(N-vinyl pyrrolidone, the most effective additive, was in specific interaction with IBU, as revealed by IR spectroscopy. The addition of the polymers was combined with the nanoscopic confinement to further stabilize the amorphous phase. Still, the IBU with addition of polymeric additives showed sustained release behavior. The current study suggested that the inhibition of the crystal nucleation was probably the most important factor to stabilize the amorphous phase and fully harness its high solubility.

  17. Morphology and orientation of β-BaB2O4 crystals patterned by laser in the inside of samarium barium borate glass

    Science.gov (United States)

    Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi; Komatsu, Takayuki

    2015-01-01

    Nonlinear optical β-BaB2O4 crystal lines (β-BBO) were patterned in the inside of 8Sm2O3-42BaO-50B2O3 glass by irradiations of continuous-wave Yb:YVO4 lasers with a wavelength of 1080 nm (power: P=0.8-1.0 W, scanning speed: S=0.2-2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., Dmax~100 μm at P=0.8 W, Dmax~170 μm at P=0.9 W, and Dmax~200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids.

  18. Phase equilibrium, crystallization behavior and thermodynamic studies of (m-dinitrobenzene + vanillin) eutectic system

    International Nuclear Information System (INIS)

    Graphical abstract: The phase diagram of (m-dinitrobenzene + vanillin) system. - Highlights: • (Thaw + melt) method has shown that (m-dinitrobenzene + vanillin) system forms simple eutectic type phase diagram. • Excess thermodynamic functions showed that eutectic mixture is non-ideal. • The flexural strength measurements have shown that in eutectic mixture, crystallization occurs in an ordered way. - Abstract: The phase diagram of (m-dinitrobenzene + vanillin) system has been studied by the thaw melt method and an eutectic type phase diagram was obtained. The linear velocities of crystallization of the parent components and the eutectic mixture were determined. The enthalpy of fusion of the components and the eutectic mixture were determined using the differential scanning calorimetric technique. Excess Gibbs energy, excess entropy, excess enthalpy of mixing, and interfacial energy have been calculated. FTIR spectroscopic studies and flexural strength measurements were also made. The results have shown that the eutectic is a non-ideal mixture of the two components. On the basis of Jackson’s roughness parameter, it is predicted that the eutectic has faceted morphology

  19. Magnetic properties and crystallization behavior of nanocrystalline FeSiBPCuAl alloys

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Magnetic properties and crystallization behavior of nanocrystalline (Fe83.3Si4B8P4Cu0.7)100-xAlx (x=0-1.5 at%) alloys were investigated in this study.Experimental results show that coercive force decreases and saturation magnetization slightly decreases with the increase of Al content,but the glass forming ability has been improved at the same time.Crystallization behavior including the evolution of microstructure has also been studied.The growth of α-Fe precipitated from the matrix is quick when it is annealed by conventional method and the mean size of α-Fe grains increases from below 2-3 nm to 18-29 nm.Nanocrystalline (Fe83.3Si4B8P4Cu0.7)99Al1 alloy with coercive force of 8.9 A/m and saturation magnetization of 187 emu/g is probably a promising candidate in the field of soft magnetic materials.

  20. Partially transformed relaxor ferroelectric single crystals with distributed phase transformation behavior

    Science.gov (United States)

    Gallagher, John A.

    2015-11-01

    Relaxor ferroelectric single crystals such as PMN-PT and PIN-PMN-PT undergo field driven phase transformations when electrically or mechanically loaded in crystallographic directions that provide a positive driving force for the transformation. The observed behavior in certain compositions is a phase transformation distributed over a range of fields without a distinct forward or reverse coercive field. This work focuses on the material behavior that is observed when the crystals are loaded sufficiently to drive a partial transformation and then unloaded, as might occur when driving a transducer to achieve high power levels. Distributed transformations have been modeled using a normal distribution of transformation thresholds. A set of experiments was conducted to characterize the hysteresis loops that occur with the partial transformations. In this work the normal distribution model is extended to include the partial transformations that occur when the field is reversed before the transformation is complete. The resulting hysteresis loops produced by the model are in good agreement with the experimental results.

  1. Lubricating and waxy esters, I. Synthesis, crystallization, and melt behavior of linear monoesters.

    Science.gov (United States)

    Bouzidi, Laziz; Li, Shaojun; Di Biase, Steve; Rizvi, Syed Q; Narine, Suresh S

    2012-01-01

    Four pure jojoba wax-like esters (JLEs), having carbon chain length of 36, 40 (two isomers) and 44, were prepared by Steglish esterification of fatty acids (or acid chlorides) with fatty alcohols at room temperature. Calorimetric and diffraction data was used to elucidate the phase behavior of the esters. The primary thermal parameters (crystallization and melting temperatures) obtained from the DSC of the symmetrical molecules correspond well with the carbon numbers of the JLEs. However, the data also suggests that carbon number is not the only factor since the symmetry of the molecule also plays a significant role in the phase behavior. Overall, the JLEs show very little polymorphic activity at the experimental conditions used, suggesting that they are likely to transform the same way during melting as well as crystallization, a characteristic which may be useful in designing new waxes and lubricants. The XRD data clearly show that the solid phase in all samples consists of a mixture of a β-phase and a β'-phase; fully distinguishable by their characteristic diffraction peaks. Subtle differences between the subcell patterns and phase development of the samples were observed. Different layering of the samples was also observed, understandably because of the chain length differences between the compounds. The long spacings were perfectly linearly proportional to the number of carbon atoms. The length of the ester layers with n carbon atoms can be calculated by a formula similar to that used for the layers in linear alkane molecules.

  2. Mo{sub 5}Si{sub 3} single crystals: Physical properties and mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chu, F.; Thoma, D.J.; McClellan, K.J.; Peralta, P.

    1998-12-01

    The materials processing, physical properties and mechanical behavior of an ultra-high temperature structural silicide, Mo{sub 5}Si{sub 3}, have been studied. High purity single crystals of Mo{sub 5}Si{sub 3} have been synthesized by both optical floating zone and Czochralski methods. The thermal and elastic properties of the MO{sub 5}Si{sub 3} single crystals were experimentally measured. Results show that Mo{sub 5}Si{sub 3} has significant thermal expansion anisotropy along the a and c directions with {alpha}{sub c}/{alpha}{sub a} = 2.2. Single crystal elastic moduli of Mo{sub 5}Si{sub 3} indicate that it has less elastic anisotropy and lower shear moduli than transition metal disilicides. Tensile stresses of up to 1.8 GPa can develop at grain boundaries after cooling from the melting point due to the thermal expansion mismatch in Mo{sub 5}Si{sub 3}, causing grain boundary cracking during processing of polycrystals. Room temperature Vickers indentation tests on (100) and (001) planes have been performed with different indenter diagonal orientations. The orientation dependence of hardness and fracture toughness of Mo{sub 5}Si{sub 3} single crystals have been obtained. The corresponding deformation and fracture modes have been revealed by microscopy studies. A comparison of Mo{sub 5}Si{sub 3} with other high temperature structural silicides, e.g., C11{sub b} and C40 transition metal disilicides, is discussed.

  3. Morphology, molecules and mating behavior : an integrative study of population divergence and speciation in widespread sepsid flies (Sepsidae: Diptera)

    OpenAIRE

    Puniamoorthy, Nalini

    2013-01-01

    The work presented in this dissertation explores processes of selection and speciation acting on diverging populations in two widespread sepsid species (Sepsidae: Diptera). The main focus was on investigating sexual selection, sexual size dimorphism (SSD) and incipient speciation in the nearctic and palaearctic species Sepsis punctum (Fabricius 1794) (Chapters 1-4). In addition, divergence in reproductive behavior and morphology was also addressed in the neotropical species Archisepsis divers...

  4. A lifelong Odyssey: from structural and morphological engineering of functional solids to bio-chirogenisis and pathological crystallization

    Science.gov (United States)

    Lahav, Meir; Leiserowitz, Leslie

    2015-11-01

    This cooperative endeavour first describes early studies in chemical crystallography, encompassing molecular packing modes, characterization of weak hydrogen bonds, the engineering of functional crystals and monitoring of reaction pathways in molecular crystals by x-ray and neutron diffraction. With the design of ‘tailor-made’ auxiliary molecules, it became possible to correlate molecular enantiomerism and crystal enantiomorphism, to control the early stages of crystal nucleation, to resolve enantiomers by crystallization, induce the precipitation of metastable polymorphs, and shed light on the role played by solvent on crystal growth. With such auxiliaries, the structure of mixed crystals was revised and the ability to perform ‘absolute’ asymmetric synthesis in host centrosymmetric crystals demonstrated. With the introduction of grazing incidence synchrotron x-ray diffraction from liquid surfaces it also became possible to design and characterize crystalline thin film architectures at the air-water interface providing a general insight on the mechanism of crystal nucleation at the molecular level, in particular that of ice and cholesterol. Finally the collective knowhow from these studies were crucial for obtaining homochiral peptides prepared from the polymerization of racemates of amphiphilic amino acids dissolved in aqueous solution, and for experiments towards elucidating the pathological crystallization of cholesterol and the malaria pigment in Plasmodium-infected red blood cells.

  5. Crystal plasticity based finite element model for simulation of high temperature deformation behavior of Niobium based alloys for high temperature reactors

    International Nuclear Information System (INIS)

    For structural components of compact high temperature reactors, Niobium based alloys are some of the candidate materials which are being studied extensively by various researchers. These alloys have excellent high temperature mechanical properties for temperature range as high as 1000 to 1300 deg. C. The NbZrC alloys form different types of carbides which impart high temperature strength to these alloys. The alloy also possesses good ductility at elevated temperatures. In order to understand the material deformation behavior of the alloy, a crystal plasticity based model has been used in simulation of material stress-strain curve at various elevated temperatures. It is very important to take into account of the underlying microstructure of the material in order to develop a reliable constitutive model for predicting the elevated temperature strength of these alloys. Crystal plasticity based models are suitable for this purpose as these take into account of the crystal orientations of different grains as well as the effect of various microstructural features on the onset of plasticity and plastic hardening mechanisms in these materials. However, it is computationally expensive to incorporate the explicit models of different features of the microstructure in a crystal plasticity based framework to simulate the response of the polycrystalline micro-structure of these alloys. The aim of this work is to develop a physically motivated multi-scale approach for simulation of response of these types of alloys. At the lower scale, i.e., at the grain level, the crystal plasticity model simulates the response of various types of microstructures (with different morphology of precipitates) within a single crystal. The microstructures are designed with various shapes and volume fractions of precipitates. The lower scale model is homogenized as a function of various microstructural parameters and the homogenized model is used at the polycrystalline level of crystal plasticity

  6. A glass-like behavior in the low-temperature specific heat is a natural property of any real crystal

    OpenAIRE

    Cano, A.; Levanyuk, A. P.; Minyukov, S. A.

    2007-01-01

    We provide a rigorous calculation of the free energy of a non-metallic crystal containing a small concentration of defects. The low-temperature leading contribution is found to be $\\propto T^2$. This further gives a linear-in-$T$ low-temperature specific heat as that exhibited by glasses. These results also show that, similarly to what happens in glasses, the long-wavelength spectrum of a nearly perfect crystal does not suffice to determine its low-temperature behavior.

  7. Thermal profiles, crystallization behaviors and microstructure of diacylglycerol-enriched palm oil blends with diacylglycerol-enriched palm olein.

    Science.gov (United States)

    Xu, Yayuan; Zhao, Xiaoqing; Wang, Qiang; Peng, Zhen; Dong, Cao

    2016-07-01

    To elucidate the possible interaction mechanisms between DAG-enriched oils, this study investigated how mixtures of DAG-enriched palm-based oils influenced the phase behavior, thermal properties, crystallization behaviors and the microstructure in binary fat blends. DAG-enriched palm oil (PO-DAGE) was blended with DAG-enriched palm olein (POL-DAGE) in various percentages (0%, 10%, 30%, 50%, 70%, 90%, 100%). Based on the observation of iso-solid diagram and phase diagram, the binary mixture of PO-DAGE/POL-DAGE showed a better compatibility in comparison with their corresponding original blends. DSC thermal profiles exhibited that the melting and crystallization properties of PO-DAGE/POL-DAGE were distinctively different from corresponding original blends. Crystallization kinetics revealed that PO-DAGE/POL-DAGE blends displayed a rather high crystallization rate and exhibited no spherulitic crystal growth. From the results of polarized light micrographs, PO-DAGE/POL-DAGE blends showed more dense structure with very small needle-like crystals than PO/POL. X-ray diffraction evaluation revealed when POL-DAGE was added in high contents to PO-DAGE, above 30%, β-polymorph dominated, and the mount of β' forms crystals was decreasing. PMID:26920306

  8. Thermal profiles, crystallization behaviors and microstructure of diacylglycerol-enriched palm oil blends with diacylglycerol-enriched palm olein.

    Science.gov (United States)

    Xu, Yayuan; Zhao, Xiaoqing; Wang, Qiang; Peng, Zhen; Dong, Cao

    2016-07-01

    To elucidate the possible interaction mechanisms between DAG-enriched oils, this study investigated how mixtures of DAG-enriched palm-based oils influenced the phase behavior, thermal properties, crystallization behaviors and the microstructure in binary fat blends. DAG-enriched palm oil (PO-DAGE) was blended with DAG-enriched palm olein (POL-DAGE) in various percentages (0%, 10%, 30%, 50%, 70%, 90%, 100%). Based on the observation of iso-solid diagram and phase diagram, the binary mixture of PO-DAGE/POL-DAGE showed a better compatibility in comparison with their corresponding original blends. DSC thermal profiles exhibited that the melting and crystallization properties of PO-DAGE/POL-DAGE were distinctively different from corresponding original blends. Crystallization kinetics revealed that PO-DAGE/POL-DAGE blends displayed a rather high crystallization rate and exhibited no spherulitic crystal growth. From the results of polarized light micrographs, PO-DAGE/POL-DAGE blends showed more dense structure with very small needle-like crystals than PO/POL. X-ray diffraction evaluation revealed when POL-DAGE was added in high contents to PO-DAGE, above 30%, β-polymorph dominated, and the mount of β' forms crystals was decreasing.

  9. A study on ice crystal formation behavior at intracellular freezing of plant cells using a high-speed camera.

    Science.gov (United States)

    Ninagawa, Takako; Eguchi, Akemi; Kawamura, Yukio; Konishi, Tadashi; Narumi, Akira

    2016-08-01

    Intracellular ice crystal formation (IIF) causes several problems to cryopreservation, and it is the key to developing improved cryopreservation techniques that can ensure the long-term preservation of living tissues. Therefore, the ability to capture clear intracellular freezing images is important for understanding both the occurrence and the IIF behavior. The authors developed a new cryomicroscopic system that was equipped with a high-speed camera for this study and successfully used this to capture clearer images of the IIF process in the epidermal tissues of strawberry geranium (Saxifraga stolonifera Curtis) leaves. This system was then used to examine patterns in the location and formation of intracellular ice crystals and to evaluate the degree of cell deformation because of ice crystals inside the cell and the growing rate and grain size of intracellular ice crystals at various cooling rates. The results showed that an increase in cooling rate influenced the formation pattern of intracellular ice crystals but had less of an effect on their location. Moreover, it reduced the degree of supercooling at the onset of intracellular freezing and the degree of cell deformation; the characteristic grain size of intracellular ice crystals was also reduced, but the growing rate of intracellular ice crystals was increased. Thus, the high-speed camera images could expose these changes in IIF behaviors with an increase in the cooling rate, and these are believed to have been caused by an increase in the degree of supercooling.

  10. Robustness of the periodic and chaotic orientational behavior of tumbling nematic liquid crystals.

    Science.gov (United States)

    Heidenreich, Sebastian; Ilg, Patrick; Hess, Siegfried

    2006-06-01

    The dynamical behavior of molecular alignment strongly affects physical properties of nematic liquid crystals. A theoretical description can be made by a nonlinear relaxation equation of the order parameter and leads to the prediction that rather complex even chaotic orientational behavior occur. Here the influence of fluctuating shear rates on the orientational dynamics especially on chaotic solutions is discussed. With the help of phase portraits and time evolution diagrams, we investigated the influence of different fluctuation strengths on the flow aligned, isotropic, and periodic solutions. To explore the effect of fluctuations on the chaotic behavior, we calculated the largest Lyapunov exponent for different fluctuation strengths. We found in all cases that small fluctuations of the shear rate do not affect the basic features of the dynamics of tumbling nematics. Furthermore, we present an amended potential modeling the isotropic to nematic transition and discuss the equivalence and difference to the commonly used Landau-de Gennes potential. In contrast to the Landau-de Gennes potential, our potential has the advantage to restrict the order parameter to physically admissible values. In the case of extensional flow, we show that the amended potential leads for increasing extensional rate to a better agreement with experimental results. PMID:16906852

  11. Robustness of the periodic and chaotic orientational behavior of tumbling nematic liquid crystals

    International Nuclear Information System (INIS)

    The dynamical behavior of molecular alignment strongly affects physical properties of nematic liquid crystals. A theoretical description can be made by a nonlinear relaxation equation of the order parameter and leads to the prediction that rather complex even chaotic orientational behavior occur. Here the influence of fluctuating shear rates on the orientational dynamics especially on chaotic solutions is discussed. With the help of phase portraits and time evolution diagrams, we investigated the influence of different fluctuation strengths on the flow aligned, isotropic, and periodic solutions. To explore the effect of fluctuations on the chaotic behavior, we calculated the largest Lyapunov exponent for different fluctuation strengths. We found in all cases that small fluctuations of the shear rate do not affect the basic features of the dynamics of tumbling nematics. Furthermore, we present an amended potential modeling the isotropic to nematic transition and discuss the equivalence and difference to the commonly used Landau-de Gennes potential. In contrast to the Landau-de Gennes potential, our potential has the advantage to restrict the order parameter to physically admissible values. In the case of extensional flow, we show that the amended potential leads for increasing extensional rate to a better agreement with experimental results

  12. Anomalous magnetoresistance behavior of superconducting Nd2-xCexCuO4-y single crystal

    International Nuclear Information System (INIS)

    Magnetoresistance measurements on a superconducting Nd2-xCexCuO4-y single crystal with Tc∼7 K were made with magnetic fields H applied parallel (H parallel c) and perpendicular (H perpendicular to c) to the tetragonal c-axis. For H parallel c, the resistive superconductive transition curves exhibit a double transition at low temperatures and high magnetic fields. This double resistive transition has a maximum near T∼1.1 K, followed by an extremely sharp transition into the superconducting state. For applied fields of 1 kOe, the resistivity first goes to zero, increases again to a finite value and then goes through a second transition. In this region, the resistivity exhibits non-ohmic behavior for low current densities and ohmic behavior for larger measuring currents. The resistivity for H perpendicular to c does not exhibit any anomalous behavior or a maximum for 0≤H≤60 kOe and 4 K≤T≤7 K. ((orig.))

  13. Magnetostrictive behaviors of Fe-Si(001) single-crystal films under rotating magnetic fields

    Science.gov (United States)

    Kawai, Tetsuroh; Aida, Takuya; Ohtake, Mitsuru; Futamoto, Masaaki

    2015-05-01

    Magnetostrictive behaviors under rotating magnetic fields are investigated for bcc(001) single-crystal films of Fe100-x-Six(x = 0, 6, 10 at. %). The magnetostriction observation directions are along bcc[100] and bcc[110] of the films. The magnetostriction waveform varies greatly depending on the observation direction. For the observation along [100], the magnetostriction waveform of all the films is bathtub-like and the amplitude stays at almost constant even when the magnetic field is increased up to the anisotropy field. On the other hand, the waveform along [110] is triangular and the amplitude increases with increasing magnetic field up to the anisotropy field and then saturates. In addition, the waveform of Fe90Si10 film is distorted triangular when the applied magnetic fields are less than its anisotropy field. These magnetostrictive behaviors under rotating magnetic fields are well explained by employing a proposed modified coherent rotation model where the anisotropy field and the magnetization reversal field are determined by using measured magnetization curves. The results show that magnetocrystalline anisotropy plays important role on magnetostrictive behavior under rotating magnetic fields.

  14. Morphogenesis and Chain Behaviors Related to Crystallization in Ultrathin Polymer Films%聚合物超薄膜结晶相关的形貌形成及链行为

    Institute of Scientific and Technical Information of China (English)

    王命泰; Hans-Georg Braun; Evelyn Meyer; 朱俊

    2006-01-01

    聚合物超薄膜结晶是高分子物理领域的一个新研究课题,近来已引起人们的关注,其为人们在真实时空下研究聚合物结晶及相关链行为提供了可能.聚合物超薄膜结晶与膜厚(D)有很强的相关性,尤其是D<20nm的薄膜在结晶形貌和结晶动力学方面与本体结晶差别很大.已有的结果主要集中在结晶形貌、晶体尺寸、晶体生长速度和习性、晶体的熔融和结晶度等方面,涉及温度、膜厚、基片性质和膜的组成和结构对结晶的影响;然而,有些实验结果和解释彼此不完全一致,甚至有时相互矛盾.本文综述和讨论了近年来在超薄膜结晶方面的研究,重点在于结晶形貌的形成和相关的聚合物链行为.%As a new and intriguing topic in polymer physics, the crystallization in ultrathin films has received a considerable attention in recent years, and it has provided opportunities for studying polymer crystallization and related chain behaviors in real space and time. The crystallization in ultrathin polymer films depends strongly on film thickness (D), particularly those with D<20 nm exhibit a great deviation from bulk crystallization both in crystalline morphology and crystallization kinetics. The accumulated studies mainly focus on the morphology, crystal dimensions, crystal growth rate and habit,crystal melting and crystallinity etc., involving the influences of temperature, film thickness, chemical property of substrate, and film composition and structure on the crystallization; however, some experimental results and interpretations are not completely consistent with each other, and even contradictory sometimes. In the present paper, the recent activities related to the crystallization in ultrathin polymer films are reviewed and discussed, with emphasis upon the morphogenesis of crystallization and related chain behaviors.

  15. Effect of metal vaporization behavior on keyhole-mode surface morphology of selective laser melted composites using different protective atmospheres

    Science.gov (United States)

    Dai, Donghua; Gu, Dongdong

    2015-11-01

    A selective laser melting (SLM) physical model of the change from heat conduction to keyhole-mode process is proposed, providing the transformation of the thermal behavior in the SLM process. Both thermo-capillary force and recoil pressure, which are the major driving forces for the molten flow, are incorporated in the formulation. The effect of the protective atmosphere on the thermal behavior, molten pool dynamics, velocity field of the evaporation material and resultant surface morphology has been investigated. It shows that the motion direction of the evaporation material plays a crucial role in the formation of the terminally solidified surface morphology of the SLM-processed part. For the application of N2 protective atmosphere, the evaporation material has a tendency to encounter in the frontier of the laser scan direction, resulting in the stack of molten material and the attendant formation of humps in the top surface. As Ar protective atmosphere is used, the vector direction of the evaporation material is typically upwards, leading to a uniform recoil pressure forced on the free surface and the formation of fine and flat melt pool surface. The surface quality and morphology are experimentally acquired, which are in a good agreement with the results predicted by simulation.

  16. Hydrothermal Synthesis, Crystal Structure and Electrochemical Behavior of 2d Hybrid Coordination Polymer

    Science.gov (United States)

    Fan, Weiqiang; Zhu, Lin; Shi, Weidong; Chen, Fuxiao; Bai, Hongye; Song, Shuyan; Yan, Yongsheng

    2013-06-01

    A novel metal-organic coordination polymer [Cu(phen)(L)0.5(H2O)]n (H4L = (N,N‧-5,5‧-bis(isophthalic acid)-p-xylylenediamine, and phen = 1,10-phenanthroline) has been hydrothermally synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction. The crystallographic data show that the title compound crystallizes in monoclinic space group P21/n with a = 10.682(2), b = 15.682(3), c = 11.909(2) Å, β = 91.39(3)°, V = 1994.3(7) Å3, C24H17CuN3O5, Mr = 490.95, Dc = 1.635 g/cm3, F(000) = 1004, Z = 4, μ(MoKα) = 1.141 mm-1, the final R = 0.0418 and wR = 0.0983 for 3578 observed reflections (I > 2σ(I)). The structural analyses reveal that the title compound exhibits shows a 2D layer structure, which are further linked by hydrogen bonding interactions to form a three-dimensional supramolecular network. In addition, the thermal stability and electrochemical behavior of title compound has been studied. CCDC: 900413.

  17. Crystallization behavior of single or pauci chain aggregates of isotactic polystyrene

    Institute of Scientific and Technical Information of China (English)

    Xin Yan; Yu Ying; Zhang Yu; Fan Zhongyong

    2006-01-01

    Single and pauci chain aggregates of isotactic polystyrene (i-PS) were prepared by the freeze-drying process from dilute solutions with the concentration from 1×10-3 to 2×10-5 g/mL.It was found by DSC measurements that the melting point of samples gradually shifted to lower temperatures with the decrease of the solution concentration used for sample preparation.As a result,the lamella thickness of bulk samples and the samples prepared by the freeze-drying process from a solution of 2×10-5 g/mL was 19.3 and 12.6 nm,respectively,At 468.3 K the half crystallization time (t1/2) of samples freeze-dried from a solution of 1×10-4 g/mL was about 36 s,which was merely one tenth of that of the bulk sample.In addition,the growth rate of spherulite (dr/dt) of samples prepared from a solution of 2×10-5 g/mL was faster than that of the bulk sample annealed at 478.3 K.All these results should be attributed to the fewer entanglements in samples prepared by freeze-drying process from dilute solutions,and presented clear evidence for the influence of chain entanglements on the crystallization behavior of polymers.

  18. Magnetic behavior of RMn2+xAl10-x (R=La,Gd) crystals

    Science.gov (United States)

    Sefat, Athena S.; Li, Bin; Bud'Ko, Sergey L.; Canfield, Paul C.

    2007-11-01

    The crystallographic and magnetic properties of the solution grown RMn2+xAl10-x ( R=Gd and La) crystals with tetragonal (P4/nmm) structure are investigated. For these, single-crystal x-ray diffraction results have shown the preferential occupation of excess manganese on the aluminum 8i crystallographic site. Due to excess Mn, there is evidence of local-moment magnetism in LaMn2+xAl10-x and their random distribution is thought to be responsible for the magnetic correlations below ˜50K and the spin-glass behavior below ˜3K . For GdMn2+xAl10-x , the extra manganese influences temperature below which the sample enters into a state with a net ferromagnetic component: TC≈16K for GdMn2.21(4)Al9.79(4) and 25.5K for GdMn2.39(2)Al9.61(2) . Assuming a linear dependence between TC and excess Mn concentration, the fully stoichiometric and ordered GdMn2Al10 should have TC≈5K .

  19. Observation of adsorption behavior of biomolecules on ferroelectric crystal surfaces with polarization domain patterns

    Science.gov (United States)

    Nakayama, Tomoaki; Isobe, Akiko; Ogino, Toshio

    2016-08-01

    Lithium tantalate (LiTaO3) is one of the ferroelectric crystals that exhibit spontaneous polarization domain patterns on its surface. We observed the polarization-dependent adsorption of avidin molecules, which are positively charged in a buffer solution at pH 7.0, on LiTaO3 surfaces caused by electrostatic interaction at an electrostatic double layer using atomic force microscopy (AFM). Avidin adsorption in the buffer solution was confirmed by scratching the substrate surfaces using the AFM cantilever, and the adsorption patterns were found to depend on the avidin concentration. When KCl was added to the buffer solution to weaken the electrostatic double layer interaction between avidin molecules and LiTaO3 surfaces, adsorption domain patterns disappeared. From the comparison between the adsorption and chemically etched domain patterns, it was found that avidin molecule adsorption is enhanced on negatively polarized domains, indicating that surface polarization should be taken into account in observing biomolecule behaviors on ferroelectric crystals.

  20. Behavior of nickel-base superalloy single crystals under thermal-mechanical fatigue

    Science.gov (United States)

    Fleury, E.; Rémy, L.

    1994-12-01

    The thermal-mechanical fatigue behavior of AM1 nickel-base superalloy single crystals is studied using a cycle from 600 °C to 1100 °C. It is found to be strongly dependent on crystallo-graphic orientation, which leads to different shapes of the stress-strain hysteresis loops. The cyclic stress-strain response is influenced by variation in Young’s modulus, flow stress, and cyclic hardening with temperature for every crystallographic orientation. The thermalmechanical fatigue life is mainly spent in crack growth. Two main crack-initiation mechanisms occur, depending on the mechanical strain range. Oxidation-induced cracking is the dominant damage mechanism in the lifetime of interest for turbine blades.

  1. Behavior of nickel-base superalloy single crystals under thermal-mechanical fatigue

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, E.: Remy, L. (Ecole des Mines de Paris (France). Centre des Materiaux)

    1994-01-01

    The thermal-mechanical fatigue behavior of AM1 nickel-base superalloy single crystals is studied using a cycle from 600[degree]C to 1,100[degree]C. It is found to be strongly dependent on crystallographic orientation, which leads to different shapes of the stress-strain hysteresis loops. The cyclic stress-strain response is influenced by variation in Young's modulus, flow stress, and cyclic hardening with temperature for every crystallographic orientation. The thermal-mechanical fatigue life is mainly spent in crack growth. Two main crack-initiation mechanisms occur, depending on the mechanical strain range. Oxidation-induced cracking is the dominant damage mechanism in the lifetime of interest for turbine blades.

  2. Shape Memory Behavior of [111]-Oriented NiTi Single Crystals After Stress-Assisted Aging

    Institute of Scientific and Technical Information of China (English)

    Irfan Kaya; Hirobumi Tobe; Haluk Ersin Karaca; Emre Acar; Yuriy Chumlyakov

    2016-01-01

    The shape memory behavior of [111]-oriented NistTi49 (at.%) single crystals was investigated after stressassisted aging at 500 ℃ for 1.5 h under a compressive stress of-150 MPa.It was found that a single family of Ni4Ti3 precipitates with two crystallographically equivalent variants was formed after aging under compressive stress.Stressassisted aging resulted in tensile two-way shape memory effect strain of 1.56% under-5 MPa.Thermal cycling under -600 MPa resulted in a transformation strain of-2.15%,while the subsequent thermal cycling under-5 MPa resulted in a tensile two-way shape memory effect strain of 2.2%.

  3. Crack growth behavior of SRR99 single crystal superalloy under thermal fatigue

    Institute of Scientific and Technical Information of China (English)

    LIU Yuan; YU Jinjiang; XU Yan; SUN Xiaofeng; GUAN Hengrong; HU Zhuangqi

    2008-01-01

    The thermal fatigue behavior of a single crystal superalloy SRR99 was investigated.Specimens with V-type notch were tested at the peak temperatures of 900,1000,and 1100℃.The crack growth curves as a function of the number of cycles were plotted.With the increase of peak temperature,the crack initiation life was shortened dramatically.Through optical microscopy (OM) and scanning electron microscopy (SEM) observation,it was found that multiple small cracks nucleated at the notch tip region but only one or two of them continued to develop in the following thermal cycles.The primary cracks generally propagated along a preferential direction.Microstructure changes after thermal fatigue were also discussed on the basis of SEM observation.

  4. Crystallization behaviors of Ga30Sb70/GeTe nanocomposite multilayer thin films

    Science.gov (United States)

    He, Zifang; Feng, Xiaoyi; Liu, RuiRui; Zhai, Jiwei; Changzhou, Wang

    2016-05-01

    The multi-step phase change behaviors in Ga30Sb70/GeTe (GS/GT) nanocomposite multilayer films are investigated through in situ film resistance and x-ray diffraction (XRD) measurements as well as transmission electron microscopy (TEM). Analyses of XRD and TEM indicate that the multi-step phase change in GS/GT films results from its unique crystallization mechanism (amorphous-mix crystalline–crystalline). What is more, for single period samples, the thickness of each layer has an obvious influence on multi-step transition performance. In terms of [GS(a nm)/GT(a nm)]1 film configuration, the optimized thickness of each layer should be in the range 50–100 nm. Above all, GS/GT nanocomposite thin films with one period harbor great potential for high-density phase change random access memory applications.

  5. Crystallization Behavior of Amorphous Si3N4 and Particle Size Control of the Crystallized α-Si3N4.

    Science.gov (United States)

    Chung, Yong-Kwon; Kim, Shin-A; Koo, Jae-Hong; Oh, Hyeon-Cheol; Chi, Eun-Ok; Hahn, Jee-Hyun; Park, Chan

    2016-05-01

    Amorphous silicon nitride powder prepared by low-temperature vapor-phase reaction was heat treated at various temperatures for different periods of time to examine the crystallization behavior. The effects of the heat-treatment temperature and duration on the degree of crystallization were investigated along with the effect of the heat-up rate on the particle size, and its distribution, of the crystallized α-phase silicon nitride powder. A phase transition from amorphous to α-phase occurred at a temperature above 1400 degrees C. The crystallization. process was completed after heat treatment at 1500 degrees C for 3 h or at 1550 degrees C for 1 h. The crystallization process starts at the surface of the amorphous particle: while the outer regions of the particle become crystalline, the inner part remains amorphous. The re-arrangement of the Si and N atoms on the surface of the amorphous particle leads to the formation of hexagonal crystals that are separated from the host amorphous particle. The particle size and size distribution can be controlled by varying the heat-treatment profile (namely, the heat-treatment temperature, heating rate, and heating duration at the specified temperature), which can be used to control the relative extent of the nucleation and growth. The completion of most of the nucleation process by lowering the heat-up rate can be used to achieve a singlet particle size distribution. Bimodal particle size distribution can be achieved by fast heat-up during the crystallization process. PMID:27483939

  6. Mineralogy, morphology and crystal-chemistry of the monazite from Catalao 1 (Goias, Brazil); Mineralogia, morfologia e cristaloquimica da monazita de Catalao 1 (Goias, Brazil)

    Energy Technology Data Exchange (ETDEWEB)

    Toledo, Maria Cristina Motta de; Oliveira, Sonia Maria Barros de; Ferrari, Viviane Carillo [Sao Paulo Univ., SP (Brazil). Inst. de Geociencias]. E-mails: mcristol@usp.br; vferrari@usp.br; Fontan, Francois; Parseval, Philippe de [Universite Paul Sabatier, Toulouse (France). Lab. Mineralogie et Cristallographie]. E-mails: fontan@cict.fr; parseval@insatlse.fr

    2004-03-15

    The Catalao alkaline carbonatite complex hosts a number of mineral resources including monazite. This mineral is a common accessory phase in two lithological units: carbonatite and silexite. Textural evidence suggest that monazite replaced carbonates in the carbonatite and crystallized simultaneously with quartz in the silexite. Monazite was resistant to the strong laterization that affected the massif, except for the incipient transformation into gorceixite or cerianite. In both carbonatite and silexite, monazite occurs as a complex aggregate of sub-micrometric crystals, showing unusual morphological and chemical characteristics. It contains Ca, Sr, and Ba in the A-site, and shows a certain degree of hydration indicated by ATD and IV data. Structural formulae calculated on the basis of sum of cations=1 show a moderate ionic deficiency in the anionic site. Rietveld refinement indicated poor crystallinity. Notwithstanding these peculiar characteristics, cell dimensions are similar to those of standard monazite. (author)

  7. Migration of constituent atoms and interface morphology in a heterojunction between CdS and CuInSe{sub 2} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Soo, Y.L.; Huang, S.; Kao, Y.H. [Department of Physics, State University of New York at Buffalo, Amherst, New York, 14260 (United States); Deb, S.K.; Ramanathan, K. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Takizawa, T. [Nihon University (Japan)

    1999-12-01

    Angular dependence of x-ray fluorescence (ADXRF), x-ray absorption fine structure (XAFS), and grazing incidence x-ray scattering measurements were carried out using synchrotron radiation for a study of the interface morphology and migration of constituent atoms in a heterojunction formed between CdS and CuInSe{sub 2} single crystals. The advantage of using a single crystal for this study is to avoid the usually complicated problems arising from multiple phases of the Cu{endash}In{endash}Se compounds. By a comparison of the results obtained with a bare CuInSe{sub 2} single crystal, the changes of interface microstructures in the CdS/CuInSe{sub 2} heterojunction system with {ital well-defined stoichiometry} can therefore be investigated. Prominent features in the ADXRF data clearly demonstrate that both Cu and Se atoms have migrated into the CdS layer in the heterojunction while In atoms remain intact in the CuInSe{sub 2} single crystal. The local structures around Cu in the system also show a significant change after the deposition of CdS, as manifested by the appearance of new Cd near neighbors in the XAFS spectra. {copyright} {ital 1999 American Institute of Physics.}

  8. Unusual crystals of poly(ε-caprolactone) by unusual crystallisation: The effects of rapid cooling and fast solvent loss on the morphology, crystal structure and melting

    NARCIS (Netherlands)

    Sanandaji, N.; Ovaskainen, L.; Klein Gunnewiek, M.; Vancso, G.J.; Hedenqvist, M.S.; Yu, S.; Eriksson, L.; Roth, S.V.; Gedde, U.W.

    2013-01-01

    The lateral habit, unit cell structure and melting behaviour of single crystals of poly(ε-caprolactone) (PCL) prepared by the rapid expansion of a supercritical solution technique was studied by AFM at ambient and higher temperatures and by grazing-incident X-ray scattering using a synchrotron sourc

  9. Structure, morphology and optical behavior of Ni1-xCoxO thin films prepared by a modified sol-gel method

    Science.gov (United States)

    Alshahrie, Ahmed

    2016-08-01

    Nanocrystalline Ni1-xCoxO thin films (0 ≤ x ≤ 0.4) have been prepared on glass substrates using sol-gel/spin-coating technique. The effect of the concentration of cobalt ions on the structure, morphology and optical behavior of the doped NiO thin films are investigated by the X-ray diffractometer, scanning electron microscopy, Raman spectroscopy and spectrophotometer. All films showed a single phase face centered cubic structure, implying the complete solubility of the Co ions into the NiO cubic crystal up to 40 at.%, for the first time. The texture coefficient revealed that the Co ions tend to force the NiO grains to grow along (200) direction. The Raman spectroscopy showed one longitudinal optical phonon mode (LO) at 518 cm-1 and two longitudinal optical phonons mode (2LO) at 1070 cm-1. The decrease of the intensity and the shift of the peak position of the two modes, indicating the scattering contribution of the LO-mode outside the center of Brillouin zone and the creation of oxygen vacancies due to the incorporated Co ions into the NiO cubic crystals. The Ni1-xCoxO thin films have shown high optical transparency around 80%. A decrease of the band gap energy of the NiO films from 3.69 eV to 3.41 eV was observed when the concentration of Co ions increased to 10 at.%, followed by an increase to 3.58 eV as the Co ions concentration increased to 40 at.%. The high optical conductivity and low dissipation factor of the developed Ni1-xCoxO thin films will open a new avenue for future applications in the optoelectronic devices such as reflectance mirror and display light shutter.

  10. 负离子配位多面体生长基元和晶体形貌%Anionic Coordination Polyhedron Growth Units and Crystal Morphology

    Institute of Scientific and Technical Information of China (English)

    仲维卓; 罗豪甦; 华素坤; 许桂生

    2004-01-01

    本文运用负离子配位多面体生长基元理论模型讨论了负离子配位多面体在异质同构和同质异构晶体中的结晶方位和其形态之间的关系,发现晶体的生长习性与负离子配位多面体在不同面族上相互联结的稳定性密切相关.负离子配位多面体以顶角相联最稳定,以边相连次之,以面相连最不稳定.同时,本文用负离子配位多面体生长基元理论模型对极性晶体ZnO和ZnS的生长习性也做了一定的解释.%Based on the theoretical model of anionic coordination po1yhedron growth units,this paper discussed the relationship between the crystal morphology and the orientation of anionic coordination polyhedra in the isomer (rutile,brookite and anatase)and allomer (rutile and cassiterite;corundum,hematite and ilmenite). It was found that the crystal habits of these crystals were related to the stability of combination of anionic coordination polyhedron growth units with different faces.The combination of the vertexes is the best stable,the edge second and the face third.Furthermore,the morphology of polar crystals ZnS and ZnO was also interpreted in the viewpoint of anionic coordination polyhedron growth units.

  11. Growth morphology of {l_brace}1 1 0{r_brace} faces of manganese mercury thiocyanate crystals investigated by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Y.L. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China)]. E-mail: ylgeng@icm.sdu.edu.cn; Xu, D. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China)]. E-mail: xdoffice@sdu.edu.cn; Wang, X.Q. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China); Du, W. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China); Liu, H.Y. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China); Zhang, G.H. [State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100 (China)

    2006-04-10

    Atomic force microscopy is employed to investigate the surface morphology of the {l_brace}1 1 0{r_brace} faces of MMTC crystals grown at 40 deg. C at a supersaturation of {sigma} = 0.5. Growth hillocks generated by dislocation sources often appear in groups, which leads to faster growth of the local area and forming layers with large height difference up to 30 nm. Growth centers operate nearly equally during the growth process. Serried and sparse monolayer steps dominate alternately on the surface, which is thought to be distinct phenomenon of the two-metal-centered complex compounds family.

  12. Molecular Modeling and Prediction of RDX Crystal Morphology%RDX晶体形貌的分子模拟与预测

    Institute of Scientific and Technical Information of China (English)

    陈刚; 王风云

    2013-01-01

    用BFDH ( Bravais-Friedel-Donnary-Harker)和AE( Attachment Energy)模型预测了α晶形黑索今(α-RDX)的晶体形貌。结果表明,形态学上重要生长面是:(111),(020),(002),(200)和(210)面,其中(111)面是最重要的生长面。 RDX晶体重要生长面结构分析表明,(210),(002),(200)和(111)是极性晶面,而(020)是非极性晶面,其中(210)晶面极性最强。根据晶面极性预测在极性溶剂中,(210)面将成为RDX晶体形态上重要生长面,(111)面的重要性降低,而(020)面将会在晶体生长过程中逐渐消失。丙酮溶剂重结晶RDX实验表明,RDX晶体形貌上最终显露的生长面是:(210),(111),(002)和(200)面,而(020)面已消失。%The crystal morphology ofα-RDX was predicted by using Bravais-Friedel-Donnary-Harker( BFDH) and attachment energy (AE) models.Results show that the crystal important growth surfaces are morphologically (111), (020), (002), (200) and (210), in which, (111) is the most important growth surface.The analyses of the crystal growth surface structures of RDX show that (002), (200) and (111) are polar, while (020) is a non-polar surface.(210) has the strongest polarity among five growth surfaces.It can be predicted that in the polar solvent, (210) will be morphologically important growth surface and the importance of (111) is reduced, while (020) is come to be disappeared.The recrystallization experiment in acetone solvent of RDX indicates that (210), (111), (002) and (200) are revealed on the finally RDX crystal morphology, whereas (020) is disappeared.

  13. Study on the Influence of Crystal Modifiers on the CL-20 Crystal Morphology%晶形控制剂对六硝基六氮杂异伍兹烷晶形的影响研究

    Institute of Scientific and Technical Information of China (English)

    王金英; 刘慧云

    2016-01-01

    Different species and different concentrations of PVP K90 and Span 80 were chosen as crystal modifi-ers, and the CL-20 was prepared by recrystalization with solvent-nonsolvent method. The influence mechanism of the crystal modifiers were analyzed, the particle size, morphology and agglomeration of CL-20 crystals were re-searched by polarizing microscope and laser particle size analyzer, at last the crystal type of the CL-20 was identied by XRD. The results show that the different crystal growth modifiers on the crystalline morphology has a great influ-ence, pvpK90 effect is best, when its mass concentration of 0. 015% for CL-20 refine crystal grain size between 1~10 microns, and the smooth surface of ε-CL-20 crystals.%选择不同种类、不同浓度的聚乙烯吡咯烷酮K90和司班80作为晶形控制剂,采用溶剂-非溶剂法制备CL-20。分析了晶形控制剂对六硝基六氮杂异伍兹烷(CL-20)晶体的影响机理,用偏光显微镜和粒度分析仪表征CL-20的粒度、形貌及团聚现象;最后用X射线衍射仪对其晶型进行了表征。结果表明:不同种类、不同浓度的晶形控制剂对晶体形貌的影响有很大差别,聚乙烯吡咯烷酮K90效果最好,在其质量浓度为0.015%时得到粒度在1~10μm之间、分布均匀、表面光滑的ε-CL-20晶体。

  14. The thickness dependence of the crystallization behavior in sandwiched amorphous Ge2Sb2Te5 thin films

    Science.gov (United States)

    Bai, G.; Li, R.; Xu, H. N.; Xia, Y. D.; Liu, Z. G.; Lu, H. M.; Yin, J.

    2011-12-01

    The thickness dependent crystallization behavior of thin amorphous Ge2Sb2Te5(GST) films sandwiched between different cladding materials has been investigated based on a thermodynamic model. It is revealed that there is a critical thickness below which the crystallization cannot occur. The critical thickness is determined by the energy difference Δγ between the crystalline GST/substrate interface energy and the amorphous GST/substrate interface energy, the melting enthalpy, and the mole volume. The calculated result is in good agreement with the experiments. Furthermore, the crystallization temperature is also affected by interface energy difference Δγ. Larger Δγ gives rise to a higher crystallization temperature, and vice versa. This impact becomes stronger as the film thickness is decreased.

  15. Crystallization behavior of amorphous Zr70Cu20Ni10 alloy annealed at 380℃

    Institute of Scientific and Technical Information of China (English)

    王焕荣; 叶以富; 闵光辉; 张均艳; 滕新营; 石志强

    2002-01-01

    Crystallization behavior of amorphous Zr70Cu20Ni10 alloy isothermally annealed at 380℃ was first investigated by employing the differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). It has been found that an exothermic peak appears in the DSC trace when the annealing time is about 17~18min, indicating a certain phase transformation occurs in the matrix of amorphous Zr70Cu20Ni10 alloy. Meanwhile, isothermal annealing experiments for amorphous Zr70Cu20Ni10 alloy ranging from 360℃ to 400℃ with a temperature interval of 10℃ were also carried out, from which no exothermic reaction can be observed except for the case of 380℃. This behavior indicates that the phase transformation during isothermal annealing of amorphous Zr70Cu20Ni10 alloy is strongly temperature- and time-dependent. Further investigations are required to reveal the nature of such phenomenon.

  16. Annealing Behavior of New Micro-defects in p-type Large-diameter CZ-Si Crystal

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    New types of defects in 15.24 cm diameter and 20.32 cm diameter Czochralski silicon crystals were found after SCI cleaning. Their annealing behavior was studied. It was suggested that these defects become larger during high temperature annealing and disappear by annealing at 1250℃.

  17. CRYSTALLIZATION AND MULTI-MELTING BEHAVIOR OF POLY (ETHYLENE TEREPHTHALATE) MODIFIED BY SODIUM SALT OF 5-SULPHO-ISOPHTHALIC ACID

    Institute of Scientific and Technical Information of China (English)

    HU Hengliang; MU Xiangqi; WU Shizhen

    1987-01-01

    The crystallization kinetics of the copolyester, poly(ethylene terephthalate) (PET) modified by sodium salt of 5-sulpho-isophthalic acid(SIPM), was investigated by means of differential scanning calorimeter. The experimental results and polari-microscopy observation all showed that the introduction of SIPM did not affect the nucleation of crystallization. Within the temperature range between their glass transition temperature Tg and melting point T., the crystallization rate of the copolyester sample decreased with increasing content of SIPM. The relative crystallization rate constant Z of SIPM/DMT (dimethyl terephthalate) 4mol % sample was about 1% pure PET's Z value. For isothermal crystallized copolyester samples, DSC heating curves displayed multi-melting behavior. This was interpreted by molecular weight fractionation during crystallization and premelting-recrystallization mechanism. This interpretation showed why the second melting point Tm2 will change according to Hoffman-Weeks(H-W) equation[1] and the first melting point Tm1 will increase with increasing SIPM. The principal cause of these phenomena is the high temperature crystallization rate decreases rapidly with increasing SIPM.

  18. Analysis of Crystallization Behavior of Mold Fluxes Containing TiO2 Using Single Hot Thermocouple Technique

    Institute of Scientific and Technical Information of China (English)

    Yun LEI; Bing XIE; Wen-hui MA

    2016-01-01

    The crystallization behavior of mold fluxes containing 0-8 mass% TiO 2 was investigated using the single hot thermocouple technique (SHTT)and X-ray diffraction (XRD)to study the possible effects on the coordination of heat transfer control and strand lubrication for casting crack-sensitive peritectic steels.Time-temperature-transforma-tion (TTT)and continuous-cooling-transformation (CCT)curves were plotted using the data obtained from SHTT to characterize the crystallization of the mold fluxes.The results showed that crystallization of the mold fluxes during isothermal and non-isothermal processes was suppressed with TiO 2 addition.From the TTT curves,it could be seen that the incubation and growth time of crystallization increased significantly with TiO 2 addition.The CCT curves showed that the crystallization temperature initially decreased,and then suddenly increased with increasing the TiO 2 content.XRD analysis suggested the presence of cuspidine in the mold fluxes with lower TiO 2 content (< 4 mass%),while both perovskite and cuspidine were detected in the mold fluxes when the TiO 2 content was increased to 8 mass%.In addition,the growth mechanisms of the crystals changed during the isothermal crystallization process from interface-controlled growth to diffusion-controlled growth with increasing the TiO 2 content.

  19. Morphology and Crystallization of Thin Films of Asymmetric Organic-Organometallic Diblock Copolymers of Isoprene and Ferrocenyldimethylsilane

    NARCIS (Netherlands)

    Lammertink, Rob G.H.; Hempenius, Mark A.; Vancso, G. Julius

    2000-01-01

    The morphology of thin films of asymmetric block copolymers of poly(isoprene-block-ferrocenyldimethylsilane) was studied using atomic force microscopy, transmission electron microscopy, and optical microscopy. Block copolymers with the organometallic (ferrocenylsilane) phase between 20 and 28 vol %

  20. Electron microscopy observations of surface morphologies and particle arrangement behaviors of magnetic fluids

    Institute of Scientific and Technical Information of China (English)

    沈辉; 徐雪青; 王伟

    2003-01-01

    The surface morphology of quasi-periodic stripe-shaped patterns of magnetite fluids was observed in applied perpendicular magnetic fields by means of scanning electron microscopy. The nanoparticles of the magnetite fluids are arranged in oriental quasilinear chains in applied perpendicular magnetic fields as observed using transmission electron microscopy. This arrangement results from particle-particle interactions and particle-carrier liquids interactions, which are eventually controlled by the magnetic fields distribution.

  1. Activin-receptor signaling regulates cocaine-primed behavioral and morphological plasticity

    OpenAIRE

    Gancarz, Amy M.; Wang, Zi-Jun; Schroeder, Gabrielle L.; Damez-Werno, Diane; Braunscheidel, Kevin; Mueller, Lauren E.; Monica S Humby; Caccamise, Aaron; Martin, Jennifer A.; Dietz, Karen C.; Neve, Rachael L; Dietz, David M.

    2015-01-01

    Cocaine addiction is a life-long relapsing disorder that results from long-term adaptations within the brain. We find that Activin-receptor signaling, including the transcription factor Smad3, is upregulated in the rat nucleus accumbens shell following withdrawal from cocaine. Direct genetic and pharmacological manipulations of this pathway bidirectionally alter cocaine seeking, while governing morphological plasticity in nucleus accumbens neurons. These findings reveal that Activin/Smad3 sig...

  2. Thermal, mechanical and morphological behavior of starch thermoplastic (TPS) and polycaprolactone (PCL)

    International Nuclear Information System (INIS)

    Thermal, mechanical and morphological properties of thermoplastic starch (TPS) and polycaprolactone (PCL) blend obtained by extrusion was studied. The results showed that TPS/PCL blends are immiscible, however it is suggested some interaction in the interphase between TPS and PCL as observed by crystallinity decrease of the blend. The PCL addition in the TPS improves the properties and decreases the cost of the blend. (author)

  3. A Pilot Trial of Integrated Behavioral Activation and Sexual Risk Reduction Counseling for HIV-Uninfected Men Who Have Sex with Men Abusing Crystal Methamphetamine

    OpenAIRE

    Mimiaga, Matthew J.; Reisner, Sari L.; Pantalone, David W.; O'Cleirigh, Conall; Mayer, Kenneth H.; Safren, Steven A.

    2012-01-01

    Crystal methamphetamine use is a major driver behind high-risk sexual behavior among men who have sex with men (MSM). Prior work suggests a cycle of continued crystal methamphetamine use and high-risk sex due to loss of the ability to enjoy other activities, which appears to be a side effect of this drug. Behavioral activation (BA) is a treatment for depression that involves learning to reengage in life's activities. We evaluated a novel intervention for crystal methamphetamine abuse and high...

  4. A study on the effect of the polymeric additive HPMC on morphology and polymorphism of ortho-aminobenzoic acid crystals

    Science.gov (United States)

    Simone, E.; Cenzato, M. V.; Nagy, Z. K.

    2016-07-01

    In the present study, the effect of Hydroxy Propyl Methyl Cellulose (HPMC) on the crystallization of ortho-aminobenzoic acid (OABA) was investigated by seeded and unseeded cooling crystallization experiments. The influence of HPMC on the induction time, crystal shape of Forms I and II of OABA and the polymorphic transformation time was studied. Furthermore, the capability of HPMC to inhibit growth of Form I was evaluated quantitatively and modeled using population balance equations (PBE) solved with the method of moments. The additive was found to strongly inhibit nucleation and growth of Form I as well as to increase the time for the polymorphic transformation from Form II to I. Solvent was also found to influence the shape of Form I crystals at equal concentrations of HPMC. In situ process analytical technology (PAT) tools, including Raman spectroscopy, focused beam reflectance measurement (FBRM) and attenuated total reflectance (ATR) UV-vis spectroscopy were used in combination with off-line techniques, such as optical microscopy, scanning electron microscopy (SEM), Raman spectroscopy, Malvern Mastersizer and differential scanning calorimetry (DSC) to study the crystals produced. The results illustrate how shape, size and stability of the two polymorphs of OABA can be controlled and tailored using a polymeric additive.

  5. Atomic layer deposition of epitaxial layers of anatase on strontium titanate single crystals: Morphological and photoelectrochemical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, Theodore J.; Nepomnyashchii, Alexander B.; Parkinson, B. A., E-mail: bparkin1@uwyo.edu [Department of Chemistry, School of Energy Resources, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2015-01-15

    Atomic layer deposition was used to grow epitaxial layers of anatase (001) TiO{sub 2} on the surface of SrTiO{sub 3} (100) crystals with a 3% lattice mismatch. The epilayers grow as anatase (001) as confirmed by x-ray diffraction. Atomic force microscope images of deposited films showed epitaxial layer-by-layer growth up to about 10 nm, whereas thicker films, of up to 32 nm, revealed the formation of 2–5 nm anatase nanocrystallites oriented in the (001) direction. The anatase epilayers were used as substrates for dye sensitization. The as received strontium titanate crystal was not sensitized with a ruthenium-based dye (N3) or a thiacyanine dye (G15); however, photocurrent from excited state electron injection from these dyes was observed when adsorbed on the anatase epilayers. These results show that highly ordered anatase surfaces can be grown on an easily obtained substrate crystal.

  6. The Relationships between Morphological Characteristics and Foraging Behavior in Four Selected Species of Shorebirds and Water Birds Utilizing Tropical Mudflats

    Directory of Open Access Journals (Sweden)

    Nor Atiqah Norazlimi

    2015-01-01

    Full Text Available A study was conducted to investigate the relationship between the physical morphology of shorebirds and water birds (i.e., Lesser adjutant (Leptoptilos javanicus, Common redshank (Tringa totanus, Whimbrel (Numenius phaeopus, and Little heron (Butorides striata and their foraging behavior in the mudflats area of Selangor, Peninsular Malaysia, from August 2013 to July 2014 by using direct observation techniques (using binoculars and a video recorder. The actively foraging bird species were watched, and their foraging activities were recorded for at least 30 seconds for up to a maximum of five minutes. A Spearman Rank Correlation highlighted a significant relationship between bill size and foraging time (R=0.443, p<0.05, bill size and prey size (R=-0.052, p<0.05, bill size and probing depth (R=0.42, p=0.003, and leg length and water/mud depth (R=0.706, p<0.005. A Kruskal-Wallis Analysis showed a significant difference between average estimates of real probing depth of the birds (mm and species (H=15.96, p=0.0012. Three foraging techniques were recorded: pause-travel, visual-feeding, and tactile-hunting. Thus, morphological characteristics of bird do influence their foraging behavior and strategies used when foraging.

  7. The Relationships between Morphological Characteristics and Foraging Behavior in Four Selected Species of Shorebirds and Water Birds Utilizing Tropical Mudflats.

    Science.gov (United States)

    Norazlimi, Nor Atiqah; Ramli, Rosli

    2015-01-01

    A study was conducted to investigate the relationship between the physical morphology of shorebirds and water birds (i.e., Lesser adjutant (Leptoptilos javanicus), Common redshank (Tringa totanus), Whimbrel (Numenius phaeopus), and Little heron (Butorides striata)) and their foraging behavior in the mudflats area of Selangor, Peninsular Malaysia, from August 2013 to July 2014 by using direct observation techniques (using binoculars and a video recorder). The actively foraging bird species were watched, and their foraging activities were recorded for at least 30 seconds for up to a maximum of five minutes. A Spearman Rank Correlation highlighted a significant relationship between bill size and foraging time (R = 0.443, p water/mud depth (R = 0.706, p < 0.005). A Kruskal-Wallis Analysis showed a significant difference between average estimates of real probing depth of the birds (mm) and species (H = 15.96, p = 0.0012). Three foraging techniques were recorded: pause-travel, visual-feeding, and tactile-hunting. Thus, morphological characteristics of bird do influence their foraging behavior and strategies used when foraging. PMID:26345324

  8. Growth morphologies of wax in the presence of kinetic inhibitors

    Science.gov (United States)

    Tetervak, Alexander A.

    Driven by the need to prevent crystallization of normal alkanes from diesel fuels in cold climates, the petroleum industry has developed additives to slow the growth of these crystals and alter their morphologies. Although the utility of these kinetic inhibitors has been well demonstrated in the field, few studies have directly monitored their effect at microscopic morphology, and the mechanisms by which they act remain poorly understood. Here we present a study of the effects of such additives on the crystallization of long-chain n-alkanes from solution. The additives change the growth morphology from plate-like crystals to a microcrystalline mesh. When we impose a front velocity by moving the sample through a temperature gradient, the mesh growth may form a macroscopic banded pattern and also exhibit a burst-crystallization behavior. In this study, we characterize these crystallization phenomena and also two growth models: a continuum model that demonstrates the essential behavior of the banded crystallization, and a simple qualitative cellular automata model that captures basics of the burst-crystallization process. Keywords: solidification; mesh crystallization; kinetic inhibitor; burst growth.

  9. Effects of direct current on the wetting behavior and interfacial morphology between molten Sn and Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Yan; Shen, Ping, E-mail: shenping@jlu.edu.cn; Yang, Nan-Nan; Cao, Kang-Zhan

    2014-02-15

    Highlights: • Applying DC has a noticeable effect on the wetting of oxidized Cu by molten Sn. • Current polarity does not have a strong effect on wettability but on microstructure. • The IMC layer greatly thickens with increasing current intensity. • An unusual morphology was formed at the interface under a larger current intensity. -- Abstract: The effect of applying a direct electric current on the wetting behavior of molten Sn on Cu substrates at a nominal temperature of 510 K was investigated using a sessile drop method. The final stable contact angles were 37 ± 5° without employing a direct current (DC) while they decreased from 29 ± 3° to 16 ± 2° when the current increased from 2.5 A to 7.5 A. The current polarity does not have a noticeable effect on the wetting behavior but on interfacial morphology. Cross-sectional microstructure observations revealed that applying a current promoted the dissolution of the Cu substrate in molten Sn and the effect was enhanced with increasing current intensity. An unusual morphology with Cu{sub 3}Sn being the principal phase and Cu{sub 6}Sn{sub 5} being the secondary phase was observed under a relatively large current intensity, particularly for the case of electrons flowing from the Cu substrate to the molten Sn side. Joule heat-induced Marangoni convection in the liquid droplet and electromigration are likely to play significant roles in determining the wettability and interfacial microstructure under the application of a direct electric current.

  10. Fungal morphology and fragmentation behavior in a fed-batch Aspergillus oryzae fermentation at the production scale.

    Science.gov (United States)

    Li, Z J; Shukla, V; Fordyce, A P; Pedersen, A G; Wenger, K S; Marten, M R

    2000-11-01

    It is well known that high-viscosity fermentation broth can lead to mixing and oxygen mass transfer limitations. The seemingly obvious solution for this problem is to increase agitation intensity. In some processes, this has been shown to damage mycelia, affect morphology, and decrease product expression. However, in other processes increased agitation shows no effect on productivity. While a number of studies discuss morphology and fragmentation at the laboratory and pilot scale, there are relatively few publications available for production-scale fungal fermentations. The goal of this study was to assess morphology and fragmentation behavior in large-scale, fed-batch, fungal fermentations used for the production of protein. To accomplish this, a recombinant strain of Aspergillus oryzae was grown in 80 m(3) fermentors at two different gassed, impeller power-levels (one 50% greater than the other). Impeller power is reported as energy dissipation/circulation function (EDCF) and was found to have average values of 29.3 +/- 1.0 and 22.0 +/- 0.3 kW m(-3) s(-1) at high and low power levels, respectively. In all batches, biomass concentration profiles were similar and specific growth rate was batches, respectively. At the end of each batch, clumps accounted for only 25% of fungal biomass, most of which existed as small, sparsely branched, free hyphal elements. In all batches, fragmentation was found to dominate fungal growth and branching. We speculate that this behavior was due to slow growth of the culture during this fed-batch process. PMID:10992234

  11. Morphological Behavior of Lipid Bilayers Induced by Melittin near the Phase Transition Temperature

    OpenAIRE

    Toraya, Shuichi; Nagao, Takashi; Norisada, Kazushi; Tuzi, Satoru; Saitô, Hazime; Izumi, Shunsuke; Naito, Akira

    2005-01-01

    Morphological changes of DMPC, DLPC, and DPPC bilayers containing melittin (lecithin/melittin molar ratio of 10:1) around the gel-to-liquid crystalline phase transition temperatures (Tc) were examined by a variety of biophysical methods. First, giant vesicles with the diameters of ∼20 μm were observed by optical microscopy for melittin-DMPC bilayers at 27.9°C. When the temperature was lowered to 24.9°C (Tc = 23°C for the neat DMPC bilayers), the surface of vesicles became blurred and dynamic ...

  12. Effect of Y{sub 2}O{sub 3} addition on the crystal growth and sintering behavior of YSZ nanopowders prepared by a sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, C.-W.; Shen, Y.-H. [Department of Resources Engineering, National Chen Kung University, 1 Ta-Hsueh Road, Tainan 70101, Taiwan (China); Hung, I-M. [Yuan Ze Fuel Cell Center, Department of Chemical Engineering and Materials Science, Yuan Ze University, 135 Yuan-Tung Road, Chung-Li, Taoyuan 320, Taiwan (China)], E-mail: imhung@saturn.yzu.edu.tw; Wen, S.-B. [General Education Center, Meiho Institute of Technology, 23 Pingguang Road, Neipu, Pingtung 91202, Taiwan (China); Lee, H.-E. [Faculty of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Wang, M.-C. [Faculty of Fragrance and Cosmetics, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China)], E-mail: mcwang@kmu.edu.tw

    2009-03-20

    The effect of Y{sub 2}O{sub 3} (8 mol% {<=} Y{sub 2}O{sub 3} {<=} 10 mol%) addition on the crystal growth and sintering behavior of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol-gel process with various mixtures of ZrOCl{sub 2}.8H{sub 2}O and Y(NO{sub 3}){sub 3}.6H{sub 2}O ethanol-water solutions at low temperatures has been studied. X-ray diffraction (XRD), Brunauer-Emmett-Teller specific surface area analyses (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and dilatometric analysis (DA) have been utilized to characterize the YSZ nanocrystallites. Characterization reveals that the YSZ nanopowders are weakly agglomerated. When calcined at various temperatures for 2 h, the crystallite size increases and the surface area of the YSZ powders decreases when the calcination temperature increased from 673 to 1273 K. A nanocrystallite size distribution between 10 and 15 nm is obtained in the TEM examination, which is consistent with the XRD investigation. The activation energy for crystal growth were determined as 5.75 {+-} 0.68, 4.22 {+-} 0.51, and 5.24 {+-} 0.20 kJ/mol for 8, 9 and 10 YSZ precipitates, respectively. The morphology of the YSZ sintered at high temperature indicates the abnormal growth is due to the low activation energy for crystallite growth.

  13. Effect of Y2O3 addition on the crystal growth and sintering behavior of YSZ nanopowders prepared by a sol-gel process

    International Nuclear Information System (INIS)

    The effect of Y2O3 (8 mol% ≤ Y2O3 ≤ 10 mol%) addition on the crystal growth and sintering behavior of yttria-stabilized zirconia (YSZ) nanocrystallites prepared by a sol-gel process with various mixtures of ZrOCl2.8H2O and Y(NO3)3.6H2O ethanol-water solutions at low temperatures has been studied. X-ray diffraction (XRD), Brunauer-Emmett-Teller specific surface area analyses (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and dilatometric analysis (DA) have been utilized to characterize the YSZ nanocrystallites. Characterization reveals that the YSZ nanopowders are weakly agglomerated. When calcined at various temperatures for 2 h, the crystallite size increases and the surface area of the YSZ powders decreases when the calcination temperature increased from 673 to 1273 K. A nanocrystallite size distribution between 10 and 15 nm is obtained in the TEM examination, which is consistent with the XRD investigation. The activation energy for crystal growth were determined as 5.75 ± 0.68, 4.22 ± 0.51, and 5.24 ± 0.20 kJ/mol for 8, 9 and 10 YSZ precipitates, respectively. The morphology of the YSZ sintered at high temperature indicates the abnormal growth is due to the low activation energy for crystallite growth

  14. Variations in ventral root axon morphology and locomotor behavior components across different inbred strains of mice

    NARCIS (Netherlands)

    de Mooij-van Malsen, J. G.; Yu, K. L.; Veldman, H.; Oppelaar, H; van den Berg, L. H.; Olivier, B.; Kas, M. J. H.

    2009-01-01

    Locomotion is a complex behavior affected by many different brain- and spinal cord systems, as well as by variations in the peripheral nervous system. Recently, we found increased gene expression for EphA4, a gene intricately involved in motor neuron development, between high-active parental strain

  15. Electrochemical Behavior, Microstructural Analysis, and Morphological Observations in Reinforced Mortar Subjected to Chloride Ingress

    NARCIS (Netherlands)

    Koleva, D.A.; Van breugel, K.; De Wit, J.H.W.; Van Westing, E.; Boshkov, N.; Fraaij, A.L.A.

    2007-01-01

    The behavior of steel reinforcement was studied using electrochemical impedance spectroscopy (EIS) and polarization resistance (PR) techniques in conditions of chloride-induced corrosion in ordinary Portland cement-mortar specimens immersed in 7% NaCl for a test period of 120 days and compared to sp

  16. Effect of Cooling Rate on Crystallization Behavior of Milk Fat Fraction/Sunflower Oil Blends

    OpenAIRE

    Martini, Silvana; Herrera, M. L.; Hartel, R. W.

    2001-01-01

    The effect of cooling rate (slow: 0.1°C/min; fast: 5.5°C/min) on the crystallization kinetics of blends of a highmelting milk fat fraction and sunflower oil (SFO) was investigated by pulsed NMR and DSC. For slow cooling rate, the majority of crystallization had already occurred by the time the set crystallization temperature had been reached. For fast cooling rate, crystallization started after the samples reached the selected crystallization temperature, and the solid fat content curves were...

  17. A new zinc(II supramolecular square: Synthesis, crystal structure, thermal behavior and luminescence

    Directory of Open Access Journals (Sweden)

    Wang Xiu-Yan

    2015-01-01

    Full Text Available A new square-shaped Zn(II complex, namely, [Zn4(L4(phen4]•6H2O (1 (L = 2-hydroxynicotinate and phen = 1,10- phenanthroline, has been synthesized under hydrothermal condition. The crystal of 1 belongs to triclinic, space group P -1 with a = 10.773(2 Å, b = 12.641(3 Å, c = 13.573(3 Å, α = 107.44(3º, β = 102.66(3º, γ = 93.89(3°, C72H56N12O18Zn4, Mr = 1638.77, V = 1702.8(6 Å3 , Z = 1, Dc = 1.598 g/cm3 , S = 1.045, μ(MoKα = 1.475 mm-1 , F(000 = 836, R = 0.0472 and wR = 0.0919. In 1, four L ligands bridge four Zn(II atoms to form a square-shaped structure, where four phen ligands are respectively located on four corners of the square. The π-π stacking interactions extend the adjacent squares into a 1D supramolecular chain. The thermal behavior of 1 has been characterized. Moreover, its solid state luminescence property has been studied at room temperature.

  18. Influence of Crystal Allomorph and Crystallinity on the Products and Behavior of Cellulose during Fast Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mukarakate, Calvin; Mittal, Ashutosh; Ciesielski, Peter N.; Budhi, Sridhar; Thompson, Logan; Iisa, Kristiina; Nimlos, Mark R.; Donohoe, Bryon S.

    2016-09-06

    Cellulose is the primary biopolymer responsible for maintaining the structural and mechanical integrity of cell walls and, during the fast pyrolysis of biomass, may be restricting cell wall expansion and inhibiting phase transitions that would otherwise facilitate efficient escape of pyrolysis products. Here, we test whether modifications in two physical properties of cellulose, its crystalline allomorph and degree of crystallinity, alter its performance during fast pyrolysis. We show that both crystal allomorph and relative crystallinity of cellulose impact the slate of primary products produced by fast pyrolysis. For both cellulose-I and cellulose-II, changes in crystallinity dramatically impact the fast pyrolysis product portfolio. In both cases, only the most highly crystalline samples produced vapors dominated by levoglucosan. Cellulose-III, on the other hand, produces largely the same slate of products regardless of its relative crystallinity and produced as much or more levoglucosan at all crystallinity levels compared to cellulose-I or II. In addition to changes in products, the different cellulose allomorphs affected the viscoelastic properties of cellulose during rapid heating. Real-time hot-stage pyrolysis was used to visualize the transition of the solid material through a molten phase and particle shrinkage. SEM analysis of the chars revealed additional differences in viscoelastic properties and molten phase behavior impacted by cellulose crystallinity and allomorph. Regardless of relative crystallinity, the cellulose-III samples displayed the most obvious evidence of having transitioned through a molten phase.

  19. The optimization of a woodpile photonic crystal and its negative refractive behavior

    International Nuclear Information System (INIS)

    In this paper, three-dimensional woodpile photonic crystals (PhCs) are investigated for various applications. In order to obtain PhCs with maximal photonic band gap, we optimize the size of 3D woodpile PhC by employing design of experiments. From the response surface model, which is a function of geometric design parameters, the photonic band gap is readily predicted, and the size ratios can be optimized. In addition, the PhC exhibits a negative refractive behavior due to its highly-anisotropic and wavelength-dependent dispersion properties. In order to predict the refracting angles of light inside the PhC, we investigate equi-frequency surfaces throughout the Brillouin zone. To verify that the refracting angles from the band structure calculation are reasonable, we perform finite difference time domain (FDTD) simulations. The tendency of the refracting angle with respect to wavelength and incident angle is examined by showing the wave propagation inside the PhC come from the FDTD simulations.

  20. Surfactant-induced morphology and thermal behavior of polymer layered silicate nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Marras, S I [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Tsimpliaraki, A [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Zuburtikudis, I [Department of Industrial Design Engineering, TEI of Western Macedonia, 50100 Kozani (Greece); Panayiotou, C [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2007-04-15

    Poly(L-lactic acid) nanocomposites were prepared by the addition of montmorillonite modified with various loadings of hexadecylammonium cation. The influence of alkylammonium on the morphology and surface charge of the clay was investigated by Xray diffraction (XRD) analysis and electrokinetic measurements, respectively. The structural characteristics of the inorganic-organic hybrids were studied by XRD, transmission electron microscopy (TEM) and atomic force microscopy (AFM). Thermal analysis was carried out by thermogravimetric analysis (TGA) under constant nitrogen flow and under air. The results showed that high concentration of surfactant present in the clay greatly increases clay's dispersibility into the matrix and this substantially improves the thermal stability of the pristine polymer.

  1. Bortezomib-induced painful peripheral neuropathy: an electrophysiological, behavioral, morphological and mechanistic study in the mouse.

    Directory of Open Access Journals (Sweden)

    Valentina A Carozzi

    Full Text Available Bortezomib is the first proteasome inhibitor with significant antineoplastic activity for the treatment of relapsed/refractory multiple myeloma as well as other hematological and solid neoplasms. Peripheral neurological complications manifesting with paresthesias, burning sensations, dysesthesias, numbness, sensory loss, reduced proprioception and vibratory sensitivity are among the major limiting side effects associated with bortezomib therapy. Although bortezomib-induced painful peripheral neuropathy is clinically easy to diagnose and reliable models are available, its pathophysiology remains partly unclear. In this study we used well-characterized immune-competent and immune-compromised mouse models of bortezomib-induced painful peripheral neuropathy. To characterize the drug-induced pathological changes in the peripheral nervous system, we examined the involvement of spinal cord neuronal function in the development of neuropathic pain and investigated the relevance of the immune response in painful peripheral neuropathy induced by bortezomib. We found that bortezomib treatment induced morphological changes in the spinal cord, dorsal roots, dorsal root ganglia (DRG and peripheral nerves. Neurophysiological abnormalities and specific functional alterations in Aδ and C fibers were also observed in peripheral nerve fibers. Mice developed mechanical allodynia and functional abnormalities of wide dynamic range neurons in the dorsal horn of spinal cord. Bortezomib induced increased expression of the neuronal stress marker activating transcription factor-3 in most DRG. Moreover, the immunodeficient animals treated with bortezomib developed a painful peripheral neuropathy with the same features observed in the immunocompetent mice. In conclusion, this study extends the knowledge of the sites of damage induced in the nervous system by bortezomib administration. Moreover, a selective functional vulnerability of peripheral nerve fiber subpopulations

  2. Dynamic Behavior of Hybrid APM (Advanced Pore Morphology Foam) and Aluminum Foam Filled Structures

    OpenAIRE

    Joerg Weise; Valerio Mussi; Michele Monno; Massimo Goletti; Joachim Baumeister

    2012-01-01

    The aim of this work is to evaluate the effect of different densities of hybrid aluminum polymer foam on the frequency behavior of a foam filled steel structure with different ratios between steel and foam masses. The foam filled structure is composed of three steel tubes with a welded flange at both ends bolted together to form a portal grounded by its free ends. Structure, internal and ground constraints have been designed and manufactured in order to minimize nonlinear effects and to guara...

  3. Morphological and behavioral changes in the pathogenesis of a novel mouse model of communicating hydrocephalus.

    Directory of Open Access Journals (Sweden)

    Allison B McMullen

    Full Text Available The Ro1 model of hydrocephalus represents an excellent model for studying the pathogenesis of hydrocephalus due to its complete penetrance and inducibility, enabling the investigation of the earliest cellular and histological changes in hydrocephalus prior to overt pathology. Hematoxylin and eosin staining, immunofluorescence and electron microscopy were used to characterize the histopathological events of hydrocephalus in this model. Additionally, a broad battery of behavioral tests was used to investigate behavioral changes in the Ro1 model of hydrocephalus. The earliest histological changes observed in this model were ventriculomegaly and disorganization of the ependymal lining of the aqueduct of Sylvius, which occurred concomitantly. Ventriculomegaly led to thinning of the ependyma, which was associated with periventricular edema and areas of the ventricular wall void of cilia and microvilli. Ependymal denudation was subsequent to severe ventriculomegaly, suggesting that it is an effect, rather than a cause, of hydrocephalus in the Ro1 model. Additionally, there was no closure of the aqueduct of Sylvius or any blockages within the ventricular system, even with severe ventriculomegaly, suggesting that the Ro1 model represents a model of communicating hydrocephalus. Interestingly, even with severe ventriculomegaly, there were no behavioral changes, suggesting that the brain is able to compensate for the structural changes that occur in the pathogenesis of hydrocephalus if the disorder progresses at a sufficiently slow rate.

  4. Influence of surface morphology and surface area on release behavior of hydrogen isotopes in LiNbO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Deqiong, E-mail: zhudeqiong@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Oda, Takuji [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Tanaka, Satoru [Department of Nuclear Engineering and Management, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan (Japan)

    2014-11-15

    Surface processes have profound influence on tritium release behavior in ceramic breeder materials. In this paper, the release behavior of hydrogen isotopes in LiNbO{sub 3} is studied by thermal desorption spectroscopy (TDS) with focusing on the influence of the surface morphology and surface area. It is found that the amount of surface hydroxyl groups is proportional to the specific surface area and can be decreased by smoothing the surface roughness through heating pretreatment at high temperatures. The isotope exchange reaction between the surface hydroxyl groups and water molecules residue in the system is discussed and turns out to proceed fast. The release behavior of hydrogen isotopes in LiNbO{sub 3} is compared with that in Li{sub 2}TiO{sub 3} studied in our previous work. It reveals that LiNbO{sub 3} and Li{sub 2}TiO{sub 3} have similar surface environment and similar concentration of surface hydroxyl groups with the level of 10{sup 20} m{sup −2}. The formation mechanism of hydroxyl groups on the surface is discussed and a model to explain the experimental observations is proposed.

  5. A simulation study on the effects of dendritic morphology on layer V PFC pyramidal cell firing behavior

    Directory of Open Access Journals (Sweden)

    Maria Psarrou

    2014-03-01

    Full Text Available The majority of neuronal cells found in the cerebral cortex are pyramidal neurons. Their function has been associated with higher cognitive and emotional functions. Pyramidal neurons have a characteristic structure, consisting of a triangular shaped soma whereon descend two extended and complex dendritic trees, and a long bifurcated axon. All the morphological components of the pyramidal neurons exhibit significant variability across different brain areas and layers. Pyramidal cells receive numerous synaptic inputs along their structure, integration of which in space and in time generates local dendritic spikes that shape their firing pattern. In addition, synaptic integration is influenced by voltage-gated and ion channels, which are expressed in a large repertoire by pyramidal neurons. Electrophysiological categories of pyramidal cells can be established, based on the action potential frequency, generated from a fixed somatic stimulus: (1 cells that fire repetitive action potentials (Regular Spiking – RS, (2 cells that fire clusters of 2 – 5 action potentials with short ISIs (Intrinsic Bursting – IB, and (3 cells that fire in repetitive clusters of 2 – 5 action potentials with short ISIs (Repetitive Oscillatory Bursts – ROB. In vitro and in silico scientific studies, correlate the firing patterns of the pyramidal neurons to their morphological features. This study provides a quantitatively analysis via compartmental neuronal modelling of the effects of dendritic morphology and distribution and concentration of ionic mechanisms, along the basal and/or apical dendrites on the firing behavior of a 112-set of layer V rat PFC pyramidal cells. We focus on how particular morphological and passive features of the dendritic trees shape the neuronal firing patterns. Our results suggest that specific morphological parameters (such as total length, volume and branch number can discriminate the cells as RS or IB, regardless of what is the

  6. Crystal Growth Kinetics and Viscous Behavior in Ge2Sb2Se5 Undercooled Melt.

    Science.gov (United States)

    Barták, Jaroslav; Koštál, Petr; Podzemná, Veronika; Shánělová, Jana; Málek, Jiří

    2016-08-18

    Crystal growth, viscosity, and melting were studied in Ge2Sb2Se5 bulk samples. The crystals formed a compact layer on the surface of the sample and then continued to grow from the surface to the central part of the sample. The formed crystalline layer grew linearly with time, which suggests that the crystal growth is controlled by liquid-crystal interface kinetics. Combining the growth data with the measured viscosities and melting data, crystal growth could be described on the basis of standard crystal growth models. The screw dislocation growth model seems to be operative in describing the temperature dependence of the crystal growth rate in the studied material in a wide temperature range. A detailed discussion on the relation between the kinetic coefficient of crystal growth and viscosity (ukin ∝ η(-ξ)) is presented. The activation energy of crystal growth was found to be higher than the activation energy of crystallization obtained from differential scanning calorimetry, which covers the whole nucleation-growth process. This difference is considered and explained under the experimental conditions. PMID:27441575

  7. New insights into the thermal behaviour of organic ionic plastic crystals: magnetic resonance imaging of polycrystalline morphology alterations induced by solid-solid phase transitions.

    Science.gov (United States)

    Romanenko, Konstantin; Pringle, Jennifer M; O'Dell, Luke A; Forsyth, Maria

    2015-07-15

    Organic ionic plastic crystals (OIPCs) show strong potential as solid-state electrolytes for lithium battery applications, demonstrating promising electrochemical performance and eliminating the need for a volatile and flammable liquid electrolyte. The ionic conductivity (σ) in these systems has recently been shown to depend strongly on polycrystalline morphology, which is largely determined by the sample's thermal history. [K. Romanenko et al., J. Am. Chem. Soc., 2014, 136, 15638]. Tailoring this morphology could lead to conductivities sufficiently high for battery applications, so a more complete understanding of how phenomena such as solid-solid phase transitions can affect the sample morphology is of significant interest. Anisotropic relaxation of nuclear spin magnetisation provides a new MRI based approach for studies of polycrystalline materials at both a macroscopic and molecular level. In this contribution, morphology alterations induced by solid-solid phase transitions in triisobutyl(methyl)phosphonium bis(fluorosulfonyl)imide (P1444FSI) and diethyl(methyl)(isobutyl)phosphonium hexafluorophosphate (P1224PF6) are examined using magnetic resonance imaging (MRI), alongside nuclear magnetic resonance (NMR) spectroscopy, diffusion measurements and conductivity data. These observations are linked to molecular dynamics and structural behaviour crucial for the conductive properties of OIPCs. A distinct correlation is established between the conductivity at a given temperature, σ(T), and the intensity of the narrow NMR signal that is attributed to a mobile fraction, fm(T), of ions in the OIPC. To explain these findings we propose an analogy with the well-studied relationship between permeability (k) and void fraction (θ) in porous media, with k(θ) commonly quantified by a power-law dependence that can also be employed to describe σ(fm).

  8. Crystallization behavior of Fe- and Co-based bulk metallic glasses and their glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Louzguine-Luzgin, D.V., E-mail: dml@wpi-aimr.tohoku.ac.jp [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Bazlov, A.I. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); National University of Science and Technology “MISiS”, Moscow 119049 (Russian Federation); Ketov, S.V. [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, A. [International Institute of Green Materials, Josai International University, Togane 283-8555 (Japan); School of Materials Science and Engineering, Tianjin University, 300072 (China); Department of Physics, King Abdulaziz University, Jeddah 22254 (Saudi Arabia)

    2015-07-15

    In the present work we study and compare the crystallization behavior of Fe- and Co-based good bulk glass formers with an exceptionally high glass-forming ability leading to the critical thickness of cast samples reaching 1 cm. For Fe-based alloys we also investigate the effect of opposite C/B content ratio on the glass-forming ability and the crystallization behavior. The structure and phase composition of the glassy samples were examined by conventional X-ray diffractometry and transmission electron microscopy while thermal stability and phase transformations were studied by differential scanning calorimetry. The reasons for high glass-forming ability are discussed. The glass-forming ability of the studied alloys depends on both factors: the type of crystallization reaction and characteristic temperatures. - Highlights: • Crystallization of Fe-based and Co-based bulk glass-forming alloys. • The reasons for enhanced glass-forming ability of these alloys are discussed. • Low growth rate of χ-Fe{sub 36}Cr{sub 12}Mo{sub 10} phase. • Reduced liquidus temperature of Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 6}B{sub 15}RE{sub 2} alloys.

  9. Phase separation and nanocrystallization behavior above crystallization temperature in Mg–Cu–Y metallic glass thin film

    International Nuclear Information System (INIS)

    Mg–Cu–Y metallic glass thin films were deposited by magnetron sputtering. Mg58Cu29Y13 metallic glass thin film has a large supercooled liquid region (∆TX = 57.0 K) and a smooth surface (Ra = 0.485 nm). The phase separation and nanocrystallization properties of it were investigated. Scanning electron microscope observation and energy disperse spectrum analysis in the single line scan transmission electron microscope test show phase separation in the Mg58Cu29Y13 metallic glass thin film annealed slightly above glass transition temperature for 1 min. Transmission electron microscope studies show 10 nm diameter nanocrystals in the fully crystallized specimen. The crystallization behavior of it is very different from that of bulk metallic glasses. The nanocrystals structure in the film above crystallization temperature is attributed to the high nucleation rate and low nucleus growth rate in the crystallization process. - Highlights: • Mg–Cu–Y metallic glass thin films (MGTF) are fabricated by magnetron sputtering method. • 10 nm nanocrystals can form in the Mg–Cu–Y thin film by annealing. • Phase separation happens before nanocrystallization in Mg–Cu–Y MGTF. • Phase separation induced nanocrystallization behavior of Mg–Cu–Y MGTF is interpreted

  10. Effect of Emulsifiers on Crystallization Behavior of Cocoa Butter%乳化剂对可可脂结晶行为的影响

    Institute of Scientific and Technical Information of China (English)

    王风艳; 王兴国; 孙小玲; 徐春伟; 马素琴; 黄凯; 刘元法

    2012-01-01

    从结晶热力学、动力学及形态学3个方面考察了5种乳化剂对可可脂结晶行为的影响.结果表明:单甘脂的添加降低了可可脂在25~30℃温度范围内的固体脂肪含量,不利于巧克力的加工.山梨醇酐单硬脂酸酯(Span60)的添加使可可脂晶体的三维球晶生长方式向二维平面晶体生长方式转变,并显著加快可可脂的结晶速率.Span60和聚乙氧基硬脂酸山梨糖醇(Tween60)缩短了可可脂的半结晶时间,而单甘脂、卵磷脂及聚甘油多聚蓖麻酸酯(PGPR)使可可脂的半结晶时间延长.偏光显微镜结果表明乳化剂的添加使得可可脂球晶的直径增大.%The effect of emulsifiers on crystallization behavior of cocoa butter were evaluated from the aspects of thermodynamics,dynamics and morphology. Results indicated that;the addition of monoglyceride reduced the solid fat content of cocoa butter at 25~30 ℃, which was not conducive to the processing of chocolate. The three dimensional sphere -crystal growth was changed by the addition of Span60 to two - dimensional crystal growth. Meanwhile,the crystallization rate was significantly increased by the addition of Span60. The hypocrystalline time(t1/2) of cocoa butter was reduced by the addition of Span60 and Tween60,while prolonged by the addition of monoglyceride,lecithin,and PGPR. The polarized microscopy results indicated that addition of emulsifiers increased the diameter of cocoa butter sphere - crystals.

  11. Crystallization Behavior and Relaxation Dynamics of Supercooled S‑Ketoprofen and the Racemic Mixture along an Isochrone

    DEFF Research Database (Denmark)

    Adrjanowicz, Karolina; Kaminski, Kamil; Paluch, Marian;

    2015-01-01

    In this paper, we study crystallization behavior and molecular dynamics in the supercooled liquid state of the pharmaceutically important compound ketoprofen at various thermodynamic conditions. Dielectric relaxation for a racemic mixture was investigated in a wide range of temperatures and...... pure enantiomers and their 50–50 equimolar mixture in the metastable supercooled liquid state. Crystallization kinetic studies revealed that at the same isochronal conditions the behavior of the S-enantiomer and R,S-racemic mixture of ketoprofen is entirely different. This was examined in the context...... of previous results and in view of the possibility of inducing changes in the enantiomeric composition or enantiomers separation from a racemic mixture as the effect of high pressure...

  12. Influence of MCM-41 particle on mechanical and morphological behavior of polypropylene

    International Nuclear Information System (INIS)

    This study investigates the effects of different types of nanoparticles and amount of nanoparticles on morphology and mechanical performance of polypropylene (PP) composites. Three different types of nanoparticles, namely mesoporous MCM-41 (without template), mesoporous MCM-41 (with template), and mesoporous MCM-41, whose pore channels were filled with different flexible polymer inside the pore channels with the aid of supercritical CO2 are considered. PP composites containing (0.5-5 wt.%) mesoporous MCM-41 were prepared by compounding. The tensile properties of the composites determined as a function of the filler loading and the different types of nanoparticles are found to vary with the different interface between different fillers and the matrix. The results of tensile tests showed that different flexible polymer filled mesoporous MCM-41 nanoparticles could simultaneously provide PP with strengthening and toughening effects at rather low filler content (0.5 wt.%). Scanning electron microscopy studies revealed a good dispersion of the MCM-41-S-PMMA and MCM-41-S-PS particles in the PP matrix and the enhancement of the interface between PP and MCM-41 are obtained

  13. Populations of Monarch butterflies with different migratory behaviors show divergence in wing morphology.

    Science.gov (United States)

    Altizer, Sonia; Davis, Andrew K

    2010-04-01

    The demands of long-distance flight represent an important evolutionary force operating on the traits of migratory species. Monarchs are widespread butterflies known for their annual migrations in North America. We examined divergence in wing morphology among migratory monarchs from eastern and western N. America, and nonmigratory monarchs in S. Florida, Puerto Rico, Costa Rica, and Hawaii. For the three N. American populations, we also examined monarchs reared in four common environment experiments. We used image analysis to measure multiple traits including forewing area and aspect ratio; for laboratory-reared monarchs we also quantified body area and wing loading. Results showed wild monarchs from all nonmigratory populations were smaller than those from migratory populations. Wild and captive-reared eastern monarchs had the largest and most elongated forewings, whereas monarchs from Puerto Rico and Costa Rica had the smallest and roundest forewings. Eastern monarchs also had the largest bodies and high measures of wing loading, whereas western and S. Florida monarchs had less elongated forewings and smaller bodies. Among captive-reared butterflies, family-level effects provided evidence that genetic factors contributed to variation in wing traits. Collectively, these results support evolutionary responses to long-distance flight in monarchs, with implications for the conservation of phenotypically distinct wild populations. PMID:20067519

  14. Complex Behavior of Aqueous α-Cyclodextrin Solutions. Interfacial Morphologies Resulting from Bulk Aggregation.

    Science.gov (United States)

    Hernandez-Pascacio, Jorge; Piñeiro, Ángel; Ruso, Juan M; Hassan, Natalia; Campbell, Richard A; Campos-Terán, José; Costas, Miguel

    2016-07-01

    The spontaneous aggregation of α-cyclodextrin (α-CD) molecules in the bulk aqueous solution and the interactions of the resulting aggregates at the liquid/air interface have been studied at 283 K using a battery of techniques: transmission electron microscopy, dynamic light scattering, dynamic surface tensiometry, Brewster angle microscopy, neutron reflectometry, and ellipsometry. We show that α-CD molecules spontaneously form aggregates in the bulk that grow in size with time. These aggregates adsorb to the liquid/air interface with their size in the bulk determining the adsorption rate. The material that reaches the interface coalesces laterally to form two-dimensional domains on the micrometer scale with a layer thickness on the nanometer scale. These processes are affected by the ages of both the bulk and the interface. The interfacial layer formed is not in fast dynamic equilibrium with the subphase as the resulting morphology is locked in a kinetically trapped state. These results reveal a surprising complexity of the parallel physical processes taking place in the bulk and at the interface of what might have seemed initially like a simple system.

  15. Nanocomposites of cellulose/iron oxide: influence of synthesis conditions on their morphological behavior and thermal stability

    International Nuclear Information System (INIS)

    Nanocomposites of cellulose/iron oxide have been successfully prepared by hydrothermal method using cellulose solution and Fe(NO3)3·9H2O at 180 °C. The cellulose solution was obtained by the dissolution of microcrystalline cellulose in NaOH/urea aqueous solution, which is a good system to dissolve cellulose and favors the synthesis of iron oxide without needing any template or other reagents. The phases, microstructure, and morphologies of nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectra (EDS). The effects of the heating time, heating temperature, cellulose concentration, and ferric nitrate concentration on the morphological behavior of products were investigated. The experimental results indicated that the cellulose concentration played an important role in both the phase and shape of iron oxide in nanocomposites. Moreover, the nanocomposites synthesized by using different cellulose concentrations displayed different thermal stabilities. - Highlights: ► Nanocomposites of cellulose/iron oxide have been prepared by hydrothermal method. ► The cellulose concentration played an important role in the phase of iron oxide. ► The cellulose concentration played an important role in the shape of iron oxide. ► The samples displayed different thermal stabilities.

  16. Longitudinal Effects of Embryonic Exposure to Cocaine on Morphology, Cardiovascular Physiology, and Behavior in Zebrafish.

    Science.gov (United States)

    Mersereau, Eric J; Boyle, Cody A; Poitra, Shelby; Espinoza, Ana; Seiler, Joclyn; Longie, Robert; Delvo, Lisa; Szarkowski, Megan; Maliske, Joshua; Chalmers, Sarah; Darland, Diane C; Darland, Tristan

    2016-05-31

    A sizeable portion of the societal drain from cocaine abuse results from the complications of in utero drug exposure. Because of challenges in using humans and mammalian model organisms as test subjects, much debate remains about the impact of in utero cocaine exposure. Zebrafish offer a number of advantages as a model in longitudinal toxicology studies and are quite sensitive physiologically and behaviorally to cocaine. In this study, we have used zebrafish to model the effects of embryonic pre-exposure to cocaine on development and on subsequent cardiovascular physiology and cocaine-induced conditioned place preference (CPP) in longitudinal adults. Larval fish showed a progressive decrease in telencephalic size with increased doses of cocaine. These treated larvae also showed a dose dependent response in heart rate that persisted 24 h after drug cessation. Embryonic cocaine exposure had little effect on overall health of longitudinal adults, but subtle changes in cardiovascular physiology were seen including decreased sensitivity to isoproterenol and increased sensitivity to cocaine. These longitudinal adult fish also showed an embryonic dose-dependent change in CPP behavior, suggesting an increased sensitivity. These studies clearly show that pre-exposure during embryonic development affects subsequent cocaine sensitivity in longitudinal adults.

  17. Longitudinal Effects of Embryonic Exposure to Cocaine on Morphology, Cardiovascular Physiology, and Behavior in Zebrafish

    Directory of Open Access Journals (Sweden)

    Eric J. Mersereau

    2016-05-01

    Full Text Available A sizeable portion of the societal drain from cocaine abuse results from the complications of in utero drug exposure. Because of challenges in using humans and mammalian model organisms as test subjects, much debate remains about the impact of in utero cocaine exposure. Zebrafish offer a number of advantages as a model in longitudinal toxicology studies and are quite sensitive physiologically and behaviorally to cocaine. In this study, we have used zebrafish to model the effects of embryonic pre-exposure to cocaine on development and on subsequent cardiovascular physiology and cocaine-induced conditioned place preference (CPP in longitudinal adults. Larval fish showed a progressive decrease in telencephalic size with increased doses of cocaine. These treated larvae also showed a dose dependent response in heart rate that persisted 24 h after drug cessation. Embryonic cocaine exposure had little effect on overall health of longitudinal adults, but subtle changes in cardiovascular physiology were seen including decreased sensitivity to isoproterenol and increased sensitivity to cocaine. These longitudinal adult fish also showed an embryonic dose-dependent change in CPP behavior, suggesting an increased sensitivity. These studies clearly show that pre-exposure during embryonic development affects subsequent cocaine sensitivity in longitudinal adults.

  18. Longitudinal Effects of Embryonic Exposure to Cocaine on Morphology, Cardiovascular Physiology, and Behavior in Zebrafish.

    Science.gov (United States)

    Mersereau, Eric J; Boyle, Cody A; Poitra, Shelby; Espinoza, Ana; Seiler, Joclyn; Longie, Robert; Delvo, Lisa; Szarkowski, Megan; Maliske, Joshua; Chalmers, Sarah; Darland, Diane C; Darland, Tristan

    2016-01-01

    A sizeable portion of the societal drain from cocaine abuse results from the complications of in utero drug exposure. Because of challenges in using humans and mammalian model organisms as test subjects, much debate remains about the impact of in utero cocaine exposure. Zebrafish offer a number of advantages as a model in longitudinal toxicology studies and are quite sensitive physiologically and behaviorally to cocaine. In this study, we have used zebrafish to model the effects of embryonic pre-exposure to cocaine on development and on subsequent cardiovascular physiology and cocaine-induced conditioned place preference (CPP) in longitudinal adults. Larval fish showed a progressive decrease in telencephalic size with increased doses of cocaine. These treated larvae also showed a dose dependent response in heart rate that persisted 24 h after drug cessation. Embryonic cocaine exposure had little effect on overall health of longitudinal adults, but subtle changes in cardiovascular physiology were seen including decreased sensitivity to isoproterenol and increased sensitivity to cocaine. These longitudinal adult fish also showed an embryonic dose-dependent change in CPP behavior, suggesting an increased sensitivity. These studies clearly show that pre-exposure during embryonic development affects subsequent cocaine sensitivity in longitudinal adults. PMID:27258254

  19. Global Low-Energy Weak Solution and Large-Time Behavior for the Compressible Flow of Liquid Crystals

    OpenAIRE

    Wu, Guochun; Tan, Zhong

    2012-01-01

    We consider the weak solution of the simplified Ericksen-Leslie system modeling compressible nematic liquid crystal flows in $\\mathbb R^3$. When the initial data is small in $L^2$ and initial density is positive and essentially bounded, we first prove the existence of a global weak solution in $\\mathbb R^3$. The large-time behavior of a global weak solution is also established.

  20. Study of the fluorescence blinking behavior of single F2 color centers in LiF crystal

    International Nuclear Information System (INIS)

    Using confocal fluorescence microscopy technique, we observed experimentally the luminescence of single F2 color centers in LiF crystal. It is disclosed that the fluorescence shows blinking behavior. It is shown that this phenomenon is caused by the F2 center reorientation occurring during the experiment. The ratio of luminescence intensities of differently oriented centers is assessed theoretically for two different experiment configurations. The calculated ratios are in fine agreement with experimental result

  1. Impact of Argemone mexicana extracts on the cidal, morphological, and behavioral response of dengue vector, Aedes aegypti L. (Diptera: Culicidae).

    Science.gov (United States)

    Warikoo, Radhika; Kumar, Sarita

    2013-10-01

    The larvicidal, behavioral, and morphological response of dengue vector, Aedes aegypti treated with deleterious weed, Argemone mexicana, was explored. The 1,000 ppm extracts of A. mexicana leaf, stem, and roots prepared in five different solvents (petroleum ether, hexane, benzene, acetone, and ethanol) were screened for their larvicidal activity against dengue vector establishing the efficacy of petroleum ether and hexane extracts. Other extracts, unable to give 100% mortality, were considered ineffective and discarded from further study. Larvicidal bioassay conducted with selected extracts confirmed the higher efficacy of hexane extracts exhibiting 1.1- to 1.8-fold more potential than the petroleum ether extracts. The results further revealed 1.6- to 2.4-fold higher efficacy of root extracts than those prepared from the leaves and stem of A. mexicana. The hexane root extract of A. mexicana was found to be the most effective larvicide with LC50 value of 91.331 ppm after 24 h of exposure causing 1.8 and 2.4 fold more toxicity as compared to the hexane leaf and stem extracts, respectively. Prolonged exposure of the larvae to the extracts resulted in increased toxicity potential of the extracts. Observations of the treated larvae revealed excitation, violent vertical, and horizontal movements with aggressive anal biting behavior suggesting effect of extracts on their neuromuscular system. Morphological studies of the treated larvae revealed the demelanization of cuticle and shrinkage of internal cuticle of anal papillae indicating the anal papillae as the probable action sites of the A. mexicana extracts. The potential of A. mexicana as new larvicides against dengue vector are being explored.

  2. Shear Flow Induced Transition from Liquid-Crystalline to Polymer Behavior in Side-Chain Liquid Crystal Polymers

    Science.gov (United States)

    Noirez, L.; Lapp, A.

    1997-01-01

    We determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast, a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior.

  3. Altered microglia morphology and higher resilience to stress-induced depression-like behavior in CX3CR1-deficient mice.

    Science.gov (United States)

    Hellwig, Sabine; Brioschi, Simone; Dieni, Sandra; Frings, Lars; Masuch, Annette; Blank, Thomas; Biber, Knut

    2016-07-01

    Microglia are suggested to be involved in several neuropsychiatric diseases. Indeed changes in microglia morphology have been reported in different mouse models of depression. A crucial regulatory system for microglia function is the well-defined CX3C axis. Thus, we aimed to clarify the role of microglia and CX3CR1 in depressive behavior by subjecting CX3CR1-deficient mice to a particular chronic despair model (CDM) paradigm known to exhibit face validity to major depressive disorder. In wild-type mice we observed the development of chronic depressive-like behavior after 5days of repetitive swim stress. 3D-reconstructions of Iba-1-labeled microglia in the dentate molecular layer revealed that behavioral effects were associated with changes in microglia morphology towards a state of hyper-ramification. Chronic treatment with the anti-depressant venlafaxine ameliorated depression-like behavior and restored microglia morphology. In contrast, CX3CR1 deficient mice showed a clear resistance to either (i) stress-induced depressive-like behavior, (ii) changes in microglia morphology and (iii) antidepressant treatment. Our data point towards a role of hyper-ramified microglia in the etiology of chronic depression. The lack of effects in CX3CR1 deficient mice suggests that microglia hyper-ramification is controlled by neuron-microglia signaling via the CX3C axis. However, it remains to be elucidated how hyper-ramified microglia contribute to depressive-like behavior. PMID:26576722

  4. Crystallization behavior and thermal stability of poly(butylene succinate)/poly(propylene carbonate) blends prepared by novel vane extruder

    Science.gov (United States)

    Chen, Rongyuan; Zou, Wei; Zhang, Haichen; Zhang, Guizhen; Qu, Jinping

    2016-03-01

    This work focused on the study of crystallization behavior and thermal stability of degradable poly(butylene succinate) (PBS) and poly(propylene carbonate) (PPC) blends prepared by vane extruder based on elongation force field, which is novel equipment for polymer processing. Dicumyl peroxide (DCP) was applied in this work as compatibilizer for PBS/PPC blend. Crystallization behavior and melting behavior of the blends were investigated by differential scanning calorimetry (DSC) testing. Thermal stability of the blends was studied by thermogravimetric (TG) testing. Furthermore, the melt flow indices (MFI) of the blends were examined by a MFI instrument. The results showed that the crystallization temperature of PBS decreased with the addition of PPC and DCP. The glass transition temperature of PPC increased and the melting temperature of the blend increased with the addition of PPC and DCP, which indicated that the entanglement between the molecular chains of PBS and PPC was enhanced. Thermogravimetric analysis showed that a two-step decomposition process of the blend occurred due to the different thermal resistance of PBS and PPC, and the addition of PBS reduced the decomposition rate of PPC. Moreover, the addition of PBS improved the melt flow property of PPC.

  5. Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(caprolactone)/chitosan blends.

    Science.gov (United States)

    Ghorbani, Fereshte Mohammad; Kaffashi, Babak; Shokrollahi, Parvin; Akhlaghi, Shahin; Hedenqvist, Mikael S

    2016-02-01

    The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zener fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends. PMID:26652456

  6. Study of aerosol behavior on the basis of morphological characteristics during festival events in India

    Science.gov (United States)

    Agrawal, Anubha; Upadhyay, Vinay K.; Sachdeva, Kamna

    2011-07-01

    Two important festival events were selected to assess their impacts on atmospheric chemistry by understanding settling velocity and emission time of aerosols. Using high volume sampler, aerosols were collected in a sequential manner to understand settling velocity and emission time of aerosols on a particular day. Composition and total suspended particulate load of the aerosols collected during the festivals were used as markers for strengthening the assessment. Terminal settling velocity of the aerosols were calculated using morphological and elemental compositional data, obtained from scanning electron microcopy (SEM) and energy dispersive X-ray (EDX) study. Aerosol load, black carbon, aromatic carbon and terminal velocity calculations were correlated to obtain conclusion that aerosols collected on the festival day might have been emitted prior to the festival. Settling time of aerosols collected on 17th and 19th October'09 during Diwali were found to be 36.5 (1.5 days) and 12.8 h, respectively. Carbon concentration estimated using EDX was found to be almost double in the sample collected after 2 days of the festival event. This strengthens our inference of time calculation where carbon with high concentration of load must have settled approximately after two days of the event. Settling time of aerosols collected on Holi morning and afternoon was found to be 1.7 and 24.8 h, respectively. Further, because of the small distance of 5.4 km between the meteorological station and sampling site, observed TSP values were compared with theoretical load values, calculated by using visibility values taken from the meteorological data. And it was found that both experimental and calculated values are close to each other about 50% of the times, which proves the assumption that experimental and meteorological data are comparable.

  7. Morphology and Cure Behavior of Multi-walled Carbon Nanotubes-based Thermally Conductive Adhesive

    Institute of Scientific and Technical Information of China (English)

    WANG Junxia; YAN Shilin; HE Yunban; YAN Fei; XIE Beiping

    2014-01-01

    We evaluated the cure behavior of multi-walled carbon nanotubes (MWCNTs) based thermally conductive adhesive by comprehensively thermal analysis, which presented extremely complicated variability of conversion ratioαas a function of temperature with synergistic action of positive effect and negative volume-blocking effect of MWCNTs and cross-linked network of cured polymer molecules. Due to the decomposition of MWCNTs and degradation of polymer, the mass drop is dramatically obvious over the temperature range of 330-370℃. Binary resins filled with acid-treated MWCNTs present similar reaction interval as neat epoxy and matrix resins, which is distinct from the material filled with raw MWCNTs. The alteration of the crystalline temperature and cure temperature of resins is attributed to heterogeneous nucleation of MWCNTs in matrix resins. The-COOH group of acid-treated MWCNTs reacts with epoxy groups and thus generates cross-linking, accelerates the reaction rate and reduces the cure temperature.

  8. Seasonal changes in coastal dynamics and morphological behavior of the central and southern Changjiang River delta

    Institute of Scientific and Technical Information of China (English)

    杨世伦; 赵庆英; 陈沈良; 丁平兴

    2001-01-01

    Seasonal changes in sea level, tidal range, wind, riverine discharges, nearshore SSC (suspended sediment concentration) and bed-level of intertidal flat at 4 different sites were shown. In addition, the statistical relationships between the dynamics and the behavior of the sediment surface were examined. The average intertidal elevation seems negatively correlated to sea level while positively correlated to nearshore SSC. The effect of wind on seasonal cycle of average intertidal elevation is not evident although wind is an important factor governing short-term erosion/accretion events. The influence of riverine discharges on seasonal cycle of deltaic intertidal flats is masked by other factors. It is concluded that seasonality on mudflats is more complicated than on beaches.

  9. Investigation of the influence of vanadium, iron and nickel dopants on the morphology, and crystal structure and photocatalytic properties of titanium dioxide based nanopowders.

    Science.gov (United States)

    Shao, Godlisten N; Jeon, Sun-Jeong; Haider, M Salman; Abbass, Nadir; Kim, Hee Taik

    2016-07-15

    Photoactive V, Fe and Ni doped TiO2 (M-TiO2) nanopowders were synthesized by a modified two-step sol-gel process in the absence of additives. Titanium oxychloride, which is a rarely-used TiO2 precursor was used to yield M-TiO2 photocatalysts with preferential photochemical performance in the presence of natural solar irradiation. The obtained samples were calcined at different calcination temperatures ranging from 450 to 800°C to evaluate the influence of the sintering on the physicochemical properties. The properties of the obtained samples were examined by XRF, XRD, Raman spectroscopy, UV-visible DRS, XPS, nitrogen gas physisorption studies, SEM-EDAX and HRTEM analyses. Structural characterization of the samples revealed the incorporation of these transition metal element into TiO2. It was also depicted that the morphology, crystal structure, optical and photochemical properties of the obtained samples were largely dependent on the calcination temperature and the type of dopant used during the preparation process. The photochemical performance of the samples was investigated in the photodegradation of methylene blue in the presence of natural sunlight. The experimental results indicated that the VT600 sample possessed the highest activity due to its superior properties. This study provides a systematic preparation and selection of the precursor, dopant and calcination temperature that are suitable for the formation of TiO2-based heterogeneous photocatalysts with appealing morphology, crystal structure, optical and photochemical properties for myriad of applications. PMID:27124812

  10. Morphological stability of the atomically clean surface of silicon (100) crystals after microwave plasma-chemical processing

    International Nuclear Information System (INIS)

    The morphological stability of atomically clean silicon (100) surface after low-energy microwave plasma-chemical etching in various plasma-forming media is studied. It is found that relaxation changes in the surface density and atomic bump heights after plasma processing in inert and chemically active media are multidirectional in character. After processing in a freon-14 medium, the free energy is minimized due to a decrease in the surface density of microbumps and an increase in their height. After argon-plasma processing, an insignificant increase in the bump density with a simultaneous decrease in bump heights is observed. The physicochemical processes causing these changes are considered

  11. Morphological stability of the atomically clean surface of silicon (100) crystals after microwave plasma-chemical processing

    Energy Technology Data Exchange (ETDEWEB)

    Yafarov, R. K., E-mail: pirpc@yandex.ru; Shanygin, V. Ya. [Russian Academy of Sciences, Saratov Branch of the Kotel’nikov Institute of Radio Engineering and Electronics (Russian Federation)

    2016-01-15

    The morphological stability of atomically clean silicon (100) surface after low-energy microwave plasma-chemical etching in various plasma-forming media is studied. It is found that relaxation changes in the surface density and atomic bump heights after plasma processing in inert and chemically active media are multidirectional in character. After processing in a freon-14 medium, the free energy is minimized due to a decrease in the surface density of microbumps and an increase in their height. After argon-plasma processing, an insignificant increase in the bump density with a simultaneous decrease in bump heights is observed. The physicochemical processes causing these changes are considered.

  12. Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control of their size, crystal phase and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jingkun; Chen, D-R; Biswas, Pratim [Aerosol and Air Quality Research Laboratory, Department of Energy, Environmental and Chemical Engineering, Washington University in St Louis, Campus Box 1180, St Louis, MO 63130 (United States)

    2007-07-18

    A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties (crystal phase and size) that could be independently controlled. The methodology was demonstrated for TiO{sub 2} nanoparticles, and this is the first time that large sets of samples with the same size but different crystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree of TiO{sub 2} nanoparticle agglomeration was determined by comparing the primary particle size distribution measured by scanning electron microscopy (SEM) to the mobility-based particle size distribution measured by online scanning mobility particle spectrometry (SMPS). By controlling the flame aerosol reactor conditions, both spherical unagglomerated particles and highly agglomerated particles were produced. To produce monodisperse nanoparticles, a high throughput multi-stage differential mobility analyser (MDMA) was used in series with the flame aerosol reactor. Nearly monodisperse nanoparticles (geometric standard deviation less than 1.05) could be collected in sufficient mass quantities (of the order of 10 mg) in reasonable time (1 h) that could be used in other studies such as determination of functionality or biological effects as a function of size.

  13. Analysis of the variation in nanohardness of pearlitic steel: Influence of the interplay between ferrite crystal orientation and cementite morphology

    International Nuclear Information System (INIS)

    The influence of the relative orientation of the ferrite crystallite lattice and the cementite lamellae on the hardness of pearlitic steel has been investigated by a combination of nanoindentation and electron microscopy (electron back scatter diffraction (EBSD) and scanning electron microscopy (SEM)). Three pearlitic samples, each with a different interlamellar spacing, and one ferritic sample were nanoindented. Although the hardness of the ferritic sample is very similar at different spots on the sample, a large variation in hardness is obtained on each of the pearlitic samples. It has been found that this variation cannot be accounted for solely by the variation in interlamellar spacing and is related to differences in ferrite crystal orientation. As to explain the observed large variation in hardness, the ferrite crystal orientation was considered relative to the cementite lamellae orientation by calculation of the distance dislocations can glide between adjacent lamellae in the slip direction. However, no clear correlation was found for a scaling of this orientation factor with the hardness. Possible interpretations of this discrepancy are suggested

  14. Analysis of the variation in nanohardness of pearlitic steel: Influence of the interplay between ferrite crystal orientation and cementite morphology

    Energy Technology Data Exchange (ETDEWEB)

    Debehets, Jolien, E-mail: jolien.debehets@mtm.kuleuven.be [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium); Tacq, Jeroen [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium); Favache, Audrey; Jacques, Pascal [Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, Place Sainte Barbe 2 L5.02.02, 1348 Louvain-la-Neuve (Belgium); Seo, Jin Won; Verlinden, Bert; Seefeldt, Marc [Department of Materials Engineering, KU Leuven, University of Leuven, Kasteelpark Arenberg 44 bus 2450, B-3001 Leuven (Belgium)

    2014-10-20

    The influence of the relative orientation of the ferrite crystallite lattice and the cementite lamellae on the hardness of pearlitic steel has been investigated by a combination of nanoindentation and electron microscopy (electron back scatter diffraction (EBSD) and scanning electron microscopy (SEM)). Three pearlitic samples, each with a different interlamellar spacing, and one ferritic sample were nanoindented. Although the hardness of the ferritic sample is very similar at different spots on the sample, a large variation in hardness is obtained on each of the pearlitic samples. It has been found that this variation cannot be accounted for solely by the variation in interlamellar spacing and is related to differences in ferrite crystal orientation. As to explain the observed large variation in hardness, the ferrite crystal orientation was considered relative to the cementite lamellae orientation by calculation of the distance dislocations can glide between adjacent lamellae in the slip direction. However, no clear correlation was found for a scaling of this orientation factor with the hardness. Possible interpretations of this discrepancy are suggested.

  15. Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

    Science.gov (United States)

    Scaffaro, R; Lopresti, F; Botta, L; Rigogliuso, S; Ghersi, G

    2016-02-01

    Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controlled by NaCl granulometry while PEG solvation created a micropores network within the devices. Scaffolds were characterized from a morphological and mechanical point of view in order to find a correlation between the preparation method, the pore architecture and compressive mechanical behavior. Biological tests were also performed in order to study the effect of pore size gradient on the permeation of different cell lines in co-culture. To imitate the physiological work condition, compressive tests were also performed in phosphate buffered saline (PBS) solution at 37°C. The presented preparation method permitted to prepare three-layered scaffolds with high control of porosity and pore size distribution. Furthermore mechanical behaviors were found to be strongly affected by pore architecture of tested devices as well as the permeation of osteoblast and fibroblast in-vitro.

  16. Preparation of three-layered porous PLA/PEG scaffold: relationship between morphology, mechanical behavior and cell permeability.

    Science.gov (United States)

    Scaffaro, R; Lopresti, F; Botta, L; Rigogliuso, S; Ghersi, G

    2016-02-01

    Interface tissue engineering (ITE) is used to repair or regenerate interface living tissue such as for instance bone and cartilage. This kind of tissues present natural different properties from a biological and mechanical point of view. With the aim to imitating the natural gradient occurring in the bone-cartilage tissue, several technologies and methods have been proposed over recent years in order to develop polymeric functionally graded scaffolds (FGS). In this study three-layered scaffolds with a pore size gradient were developed by melt mixing polylactic acid (PLA) and two water-soluble porogen agents: sodium chloride (NaCl) and polyethylene glycol (PEG). Pore dimensions were controlled by NaCl granulometry while PEG solvation created a micropores network within the devices. Scaffolds were characterized from a morphological and mechanical point of view in order to find a correlation between the preparation method, the pore architecture and compressive mechanical behavior. Biological tests were also performed in order to study the effect of pore size gradient on the permeation of different cell lines in co-culture. To imitate the physiological work condition, compressive tests were also performed in phosphate buffered saline (PBS) solution at 37°C. The presented preparation method permitted to prepare three-layered scaffolds with high control of porosity and pore size distribution. Furthermore mechanical behaviors were found to be strongly affected by pore architecture of tested devices as well as the permeation of osteoblast and fibroblast in-vitro. PMID:26410761

  17. A single point mutation changes the crystallization behavior of Mycoplasma arthritidis-derived mitogen

    International Nuclear Information System (INIS)

    The mutagenesis, crystallization and preliminary crystallographic analysis of M. arthritidis-derived mitogen is described. Mycoplasma arthritidis-derived mitogen (MAM) functions as a conventional superantigen (SAg). Although recombinant MAM has been crystallized by the hanging-drop vapour-diffusion method, the crystals diffracted poorly to only 5.0 Å resolution, with large unit-cell parameters a = 163.8, b = 93.0, c = 210.9 Å, β = 93.7° in the monoclinic space group P21. Unit-cell content analysis revealed that as many as 24 molecules could be present in the asymmetric unit. Systematic alanine mutagenesis was applied in order to search for mutants that give crystals of better quality. Two mutants, L50A and K201A, were crystallized under the same conditions as wild-type MAM (MAMwt). Crystals of the L50A mutant are isomorphous with those of MAMwt, while a new crystal form was obtained for the K201 mutant, belonging to the cubic space group P4132 with unit-cell parameters a = b = c = 181.9 Å. Diffraction data were collected to 3.6 and 2.8 Å resolution from crystals of the MAM L50A and K201A mutants, respectively. Molecular-replacement calculations suggest the presence of two molecules in the asymmetric unit for the MAM K201A mutant crystal, resulting in a VM of 5.0 Å Da−1 and a solvent content of 75%. An interpretable electron-density map for the MAM K201A mutant crystal was produced using the molecular-replacement method

  18. A single point mutation changes the crystallization behavior of Mycoplasma arthritidis-derived mitogen

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yi; Li, Zhong; Van Vranken, Sandra J. [Wadsworth Center, New York State Department of Health, Empire State Plaza, PO Box 509, Albany, New York 12201-0509 (United States); Li, Hongmin, E-mail: lih@wadsworth.org [Wadsworth Center, New York State Department of Health, Empire State Plaza, PO Box 509, Albany, New York 12201-0509 (United States); Department of Biomedical Sciences, School of Public Health, University at Albany, State University of New York, Empire State Plaza, PO Box 509, Albany, New York 12201-0509 (United States)

    2006-03-01

    The mutagenesis, crystallization and preliminary crystallographic analysis of M. arthritidis-derived mitogen is described. Mycoplasma arthritidis-derived mitogen (MAM) functions as a conventional superantigen (SAg). Although recombinant MAM has been crystallized by the hanging-drop vapour-diffusion method, the crystals diffracted poorly to only 5.0 Å resolution, with large unit-cell parameters a = 163.8, b = 93.0, c = 210.9 Å, β = 93.7° in the monoclinic space group P2{sub 1}. Unit-cell content analysis revealed that as many as 24 molecules could be present in the asymmetric unit. Systematic alanine mutagenesis was applied in order to search for mutants that give crystals of better quality. Two mutants, L50A and K201A, were crystallized under the same conditions as wild-type MAM (MAM{sub wt}). Crystals of the L50A mutant are isomorphous with those of MAM{sub wt}, while a new crystal form was obtained for the K201 mutant, belonging to the cubic space group P4{sub 1}32 with unit-cell parameters a = b = c = 181.9 Å. Diffraction data were collected to 3.6 and 2.8 Å resolution from crystals of the MAM L50A and K201A mutants, respectively. Molecular-replacement calculations suggest the presence of two molecules in the asymmetric unit for the MAM K201A mutant crystal, resulting in a V{sub M} of 5.0 Å Da{sup −1} and a solvent content of 75%. An interpretable electron-density map for the MAM K201A mutant crystal was produced using the molecular-replacement method.

  19. Dynamic Behavior of Hybrid APM (Advanced Pore Morphology Foam and Aluminum Foam Filled Structures

    Directory of Open Access Journals (Sweden)

    Joerg Weise

    2012-06-01

    Full Text Available The aim of this work is to evaluate the effect of different densities of hybrid aluminum polymer foam on the frequency behavior of a foam filled steel structure with different ratios between steel and foam masses. The foam filled structure is composed of three steel tubes with a welded flange at both ends bolted together to form a portal grounded by its free ends. Structure, internal and ground constraints have been designed and manufactured in order to minimize nonlinear effects and to guarantee optimal constraint conditions. Mode shapes and frequencies were verified with finite elements models (FEM to be in the range of experimental modal analysis, considering the frequency measurement range limits for instrumented hammer and accelerometer. Selected modes have been identified with suitable modal parameters extraction techniques. Each structure has been tested before and after filling, in order to compute the percentage variation of modal parameters. Two different densities of hybrid aluminum polymer foam have been tested and compared with structures filled with aluminum foams produced using the powder compact melting technique. All the foam fillings were able to suppress high frequency membrane modes which results in a reduction of environmental noise and an increase in performance of the components. Low frequency modes show an increase in damping ratio only when small thickness steel frames are filled with either Hybrid APM or Alulight foam.

  20. Wavelength Dependence of Laser-Induced Bulk Damage Morphology in KDP Crystal: Determination of the Damage Formation Mechanism

    Institute of Scientific and Technical Information of China (English)

    HU Guo-Hang; ZHAO Yuan-An; LI Da-Wei; XIAO Qi-Ling

    2012-01-01

    Wet etch process is applied to expose the bulk damage sites in KDP crystals to the surface for the examination by scanning electron microscopy (SEM) and optical microscopy.The damage sites induced by 1064 nm laser consist of three distinct regions:a core,an outer region of modified material,and some oriented cracks.Laser irradiated with 355 nm results in an increase of damage density,a decrease of core diameter and,rarely,occurrence of the crack.WavelengKey Laboratory of Materials for High Power Laser,Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences,Shanghai 201800th dependence of the damage feature suggests that a repulsive force exists among the adjacent plasmas,which prevents further expansion of plasma and decreases the size of plasma. The deposited energy absorbed by the smaller plasma may not be able to generate the crack.

  1. Silicon wafer wettability and aging behaviors: Impact on gold thin-film morphology

    KAUST Repository

    Yang, X. M.

    2014-10-01

    This paper reports on the wettability and aging behaviors of the silicon wafers that had been cleaned using a piranha (3:1 mixture of sulfuric acid (H2SO4, 96%) and hydrogen peroxide (H2O 2, 30%), 120 °C), SC1 (1:1:5 mixture of NH4OH, H 2O2 and H2O, at 80°C) or HF solution (6 parts of 40% NH4F and 1 part of 49% HF, at room temperature) solution, and treated with gaseous plasma. The silicon wafers cleaned using the piranha or SC1 solution were hydrophilic, and the water contact angles on the surfaces would increase along with aging time, until they reached the saturated points of around 70°. The contact angle increase rate of these wafers in a vacuum was much faster than that in the open air, because of loss of water, which was physically adsorbed on the wafer surfaces. The silicon wafers cleaned with the HF solution were hydrophobic. Their contact angle decreased in the atmosphere, while it increased in the vacuum up to 95°. Gold thin films deposited on the hydrophilic wafers were smoother than that deposited on the hydrophobic wafers, because the numerous oxygen groups formed on the hydrophilic surfaces would react with gold adatoms in the sputtering process to form a continuous thin film at the nucleation stage. The argon, nitrogen, oxygen gas plasma treatments could change the silicon wafer surfaces from hydrophobic to hydrophilic by creating a thin (around 2.5 nm) silicon dioxide film, which could be utilized to improve the roughness and adhesion of the gold thin film. © 2014 Elsevier Ltd. All rights reserved.

  2. Effect of TiO2 Content on the Crystallization Behavior of Titanium-Bearing Blast Furnace Slag

    Science.gov (United States)

    Hu, Meilong; Wei, Ruirui; Yin, Fangqing; Liu, Lu; Deng, Qingyu

    2016-09-01

    The content of TiO2 has an important influence on both the basic structure and the crystallization behavior of titanium-bearing blast furnace (BF) slag. The results of thermodynamic calculations show that, when the mass content of TiO2 is smaller than 25%, CaTiO3 increases as the content of TiO2 increases. However, when the TiO2 content is more than 25%, the CaTiO3 content decreases and TiO2 gradually increases. The results of a confocal laser scanning microscopy (CLSM) experiment show that, when the TiO2 mass content is 10%, Ca2MgSi2O7 and Ca2Al2SiO7 are the main crystallized phases resulting from the molten slag. Furthermore, when the TiO2 mass content is 20%, CaMgSi2O6, Ca(Ti,Mg,Al)(Si,Al)2O7 and dendrite CaTiO3 are the crystallized phases, while when the TiO2 mass content increases to 30%, CaTiO3 is the sole phase. The discrepancy between the CLSM results and the thermodynamic calculations occurs mainly due to the high melting point of the titanium-bearing BF slag. During the cooling process for the molten slag, CaTiO3 is crystallized first, due to its high crystallization temperature. Furthermore, the molten slag is solidified in its entirety before the other phases crystallize.

  3. Crystallization and semiconductor-metal switching behavior of thin VO2 layers grown by atomic layer deposition

    International Nuclear Information System (INIS)

    Crystalline vanadium dioxide (VO2) thin films were prepared by annealing amorphous VO2 films which were deposited by atomic layer deposition on a SiO2 substrate. A large influence of the oxygen partial pressure in the annealing ambient was observed by means of in-situ X-ray diffraction. In the range between 1 and 10 Pa of oxygen the interesting VO2(R) phase crystallized near 450 °C. Between 2 and 10 Pa of oxygen, metastable VO2(B) was observed as an intermediate crystalline phase before it transformed to VO2(R). Anneals in inert gas did not show any crystallization, while oxygen partial pressures above 10 Pa resulted in oxidation into the higher oxide phase V6O13. Film thickness did not have much effect on the crystallization behavior, but thinner films suffered more from agglomeration during the high-temperature crystallization on the SiO2 substrate. Nevertheless, continuous polycrystalline VO2(R) films were obtained with thicknesses down to 11 nm. In the case where VO2(R) was formed, the semiconductor–metal transition was observed by three complementary techniques. This transition near 68 °C was characterized by X-ray diffraction, showing the transformation of the crystal structure, by spectroscopic ellipsometry, mapping optical changes, and by sheet resistance measurements, showing resistance changes larger than 2 orders of magnitude between the low-temperature semiconducting state and the high-temperature metallic state. - Highlights: • Amorphous VO2 films were grown by atomic layer deposition. • Crystallization was studied by means of in-situ X-ray diffraction (XRD). • The optimal oxygen partial pressure during annealing was found to be around 1 Pa. • Continuous crystalline VO2 layers down to 11 nm thickness were obtained at 450 °C. • XRD, ellipsometry and sheet resistance showed the semiconductor–metal transition

  4. Thermodynamic stability and crystallization behavior of molecular complexes with TEP host

    Science.gov (United States)

    Fijiwara, Atsushi; Kitamura, Mitsutaka

    2013-06-01

    In the crystallization of molecular complex (co-crystal, clathrate complex), polymorphism in regard to the host structure frequently appears. Previously, we studied the release process of the biocide, CMI (5-chloro-2-methyl-4-isothiazolin-3-one) from the molecular complex with TEP (1,1,2,2-tetrakis(4-hydroxyphenyl)ethane) (TEP·2CMI) in methanol-water mixed solvents. It was clear that the release process of the biocide (CMI) is composed of the transformation from the TEP·2CMI crystal to a more stable molecular complex crystal with solvent. In this work, the crystallization was performed in the methanol solutions including TEP and CMI at constant temperature (298 K and 308 K). It appeared that two kinds of TEP molecular complexes (TEP·2CMI and TEP·2MeOH) crystallize competitively. The crystallization zone of each molecular complex was shown in the map using the coordinates of initial concentrations of TEP and CMI. In the boundary zone both molecular complexes appeared and the transformation from TEP·2CMI to TEP·2MeOH was observed, indicating that the stable form is TEP·2MeOH. Without the boundary zone the corresponding stable form crystallized in each zone. The value of the initial concentration ratio of CMI/TEP for the selective crystallization of TEP·2CMI was higher at 298 K (1.54) than that (1.36) at 308 K. The equilibrium concentrations of TEP and CMI in the presence of two molecular complexes were expressed using the dissociation constants of the molecular complexes and it was indicated that the dissociation of TEP·2CMI highly increases with temperature

  5. A Single Point Mutation Changes in the Crystallization Behavior of Mycoplasma arthritidis-derived Mitogen

    Energy Technology Data Exchange (ETDEWEB)

    Guo,Y.; Li, Z.; Van Vranken, S.; Li, H.

    2006-01-01

    Mycoplasma arthritidis-derived mitogen (MAM) functions as a conventional superantigen (SAg). Although recombinant MAM has been crystallized by the hanging-drop vapor-diffusion method, the crystals diffracted poorly to only 5.0 Angstroms resolution, with large unit-cell parameters a = 163.8, b = 93.0, c = 210.9 Angstroms, {beta} = 93.7 degrees in the monoclinic space group P2{sub 1}. Unit-cell content analysis revealed that as many as 24 molecules could be present in the asymmetric unit. Systematic alanine mutagenesis was applied in order to search for mutants that give crystals of better quality. Two mutants, L50A and K201A, were crystallized under the same conditions as wild-type MAM (MAM{sub wt}). Crystals of the L50A mutant are isomorphous with those of MAMwt, while a new crystal form was obtained for the K201 mutant, belonging to the cubic space group P4132 with unit-cell parameters a = b = c = 181.9 Angstroms. Diffraction data were collected to 3.6 and 2.8 Angstroms resolution from crystals of the MAM L50A and K201A mutants, respectively. Molecular-replacement calculations suggest the presence of two molecules in the asymmetric unit for the MAM K201A mutant crystal, resulting in a V{sub M} of 5.0 Angstroms Da{sup -1} and a solvent content of 75%. An interpretable electron-density map for the MAM K201A mutant crystal was produced using the molecular-replacement method.

  6. Influences of ruthenium and crystallographic orientation on creep behavior of aluminized nickel-base single crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Latief, F.H., E-mail: fahamsyah78@gmail.com [Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-shi, Tokyo 192-0397 (Japan); Kakehi, K. [Department of Mechanical Engineering, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji-shi, Tokyo 192-0397 (Japan); An-Chou Yeh, H. [Department of Materials Science and Engineering, National TsingHua University, 101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Murakami, H. [Hybrid Materials Center, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-01-13

    The influences of ruthenium and surface orientation on creep behavior of aluminized Ni-base single crystal superalloys were investigated by comparing two different types of NKH superalloys. The aluminized coated specimens were then subjected to creep rupture tests at a temperature of 900 °C and a stress of 392 MPa. The coating treatment resulted in a significant decrease in creep rupture lives for both superalloys. The diffusion zones between the coating and substrate led to changes in microstructure, which diminished the creep behavior of the aluminized superalloys. Because of the interdiffusion of Ru, Al and Ni, the solubility of some of the refractory elements, such as W, Re. Mo, Co and Cr decreased in the diffusion zone; the precipitation of topologically close-packed (TCP) phases was thus inevitable. In the present study, the addition of Ru increased the degree of Re and Cr supersaturation in the γ matrix. Consequently, the addition of Ru indirectly promoted the precipitation of TCP phases in aluminized Ni-base single crystal superalloys. Furthermore, the growth of TCP precipitates was greatly influenced by the specific surface orientations of the Ni-base single crystal superalloys. In conclusion, the {110} specimens showed shorter creep rupture life than the {100} specimens, this was due to the difference in the crystallographic geometry of {111}〈101〉 slip system and TCP precipitates between the two side-surface orientations of the specimens.

  7. Crystallization behavior of amorphous indium-gallium-zinc-oxide films and its effects on thin-film transistor performance

    Science.gov (United States)

    Suko, Ayaka; Jia, JunJun; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

    2016-03-01

    Amorphous indium-gallium-zinc oxide (a-IGZO) films were deposited by DC magnetron sputtering and post-annealed in air at 300-1000 °C for 1 h to investigate the crystallization behavior in detail. X-ray diffraction, electron beam diffraction, and high-resolution electron microscopy revealed that the IGZO films showed an amorphous structure after post-annealing at 300 °C. At 600 °C, the films started to crystallize from the surface with c-axis preferred orientation. At 700-1000 °C, the films totally crystallized into polycrystalline structures, wherein the grains showed c-axis preferred orientation close to the surface and random orientation inside the films. The current-gate voltage (Id-Vg) characteristics of the IGZO thin-film transistor (TFT) showed that the threshold voltage (Vth) and subthreshold swing decreased markedly after the post-annealing at 300 °C. The TFT using the totally crystallized films also showed the decrease in Vth, whereas the field-effect mobility decreased considerably.

  8. Non-isothermal melt crystallization behavior of Poly(ethylene terephthalate)/graphene nanocomposites

    Science.gov (United States)

    Aoyama, Shigeru; Park, Yong Tae; Ougizawa, Toshiaki; Macosko, Christopher

    2013-03-01

    Poly(ethylene terephthalate)(PET)/graphene nanocomposites were prepared by melt mixing with a goal of reduced gas permeability. With 2 wt% of few layered graphene, PET/graphene composite films show more than 70% decrease in N2 gas permeation. Their non-isothermal crystallization were also investigated by differential scanning calorimetory (DSC). Crystallization temperature, Tc, of PET/graphene nanocomposites was more than 8 °C higher than neat PET and the increment increased along with the concentration of graphene. This suggests that the nucleation effect of graphene enhanced with the increase in concentration of graphene. On the other hand, PET/graphene nanocomposites show shorter half crystallization time, t1/2, than neat PET at lower concentrations, but t1/2 increased along with concentration of graphene. From Raman spectroscopy, it was shown that PET chains in nanocomposites are strongly confined in the presence of an excess of graphene. Restricted mobility of PET chains slowed crystallization.

  9. High-pressure behavior of natural single-crystal epidote and clinozoisite up to 40 GPa

    Science.gov (United States)

    Qin, Fei; Wu, Xiang; Wang, Ying; Fan, Dawei; Qin, Shan; Yang, Ke; Townsend, Joshua P.; Jacobsen, Steven D.

    2016-06-01

    The comparative compressibility and high-pressure stability of a natural epidote (0.79 Fe-total per formula unit, Fetot pfu) and clinozoisite (0.40 Fetot pfu) were investigated by single-crystal X-ray diffraction and Raman spectroscopy. The lattice parameters of both phases exhibit continuous compression behavior up to 30 GPa without evidence of phase transformation. Pressure-volume data for both phases were fitted to a third-order Birch-Murnaghan equation of state with V 0 = 461.1(1) Å3, K 0 = 115(2) GPa, and K0' = 3.7(2) for epidote and V 0 = 457.8(1) Å3, K 0 = 142(3) GPa, and K0' = 5.2(4) for clinozoisite. In both epidote and clinozoisite, the b-axis is the stiffest direction, and the ratios of axial compressibility are 1.19:1.00:1.15 for epidote and 1.82:1.00:1.19 for clinozoisite. Whereas the compressibility of the a-axis is nearly the same for both phases, the b- and c-axes of the epidote are about 1.5 times more compressible than in clinozoisite, consistent with epidote having a lower bulk modulus. Raman spectra collected up to 40.4 GPa also show no indication of phase transformation and were used to obtain mode Grüneisen parameters (γ i) for Si-O vibrations, which were found to be 0.5-0.8, typical for hydrous silicate minerals. The average pressure coefficient of Raman frequency shifts for M-O modes in epidote, 2.61(6) cm-1/GPa, is larger than found for clinozoisite, 2.40(6) cm-1/GPa, mainly due to the different compressibility of FeO6 and AlO6 octahedra in M3 sites. Epidote and clinozoisite contain about 2 wt% H2O are thus potentially important carriers of water in subducted slabs.

  10. Leaf cuticular wax amount and crystal morphology regulate post-harvest water loss in mulberry (Morus species).

    Science.gov (United States)

    Mamrutha, H M; Mogili, T; Jhansi Lakshmi, K; Rama, N; Kosma, Dylan; Udaya Kumar, M; Jenks, Matthew A; Nataraja, Karaba N

    2010-08-01

    Mulberry leaves are the sole source of food for silkworms (Bombyx mori), and moisture content of the detached leaves fed to silkworms determines silkworm growth and cocoon yield. Since leaf dehydration in commercial sericulture is a serious problem, development of new methods that minimize post-harvest water loss are greatly needed. In the present study, variability in moisture retention capacity (MRC, measured as leaf relative water content after one to 5 h of air-drying) was examined by screening 290 diverse mulberry accessions and the relationship between MRC and leaf surface (cuticular) wax amount was determined. Leaf MRC varied significantly among accessions, and was found to correlate strongly with leaf wax amount. Scanning electron microscopic analysis indicated that leaves having crystalline surface waxes of increased facet size and density were associated with high MRC accessions. Leaf MRC at 5 h after harvest was not related to other parameters such as specific leaf weight, and stomatal frequency and index. This study suggests that mulberry accessions having elevated leaf surface wax amount and crystal size and density exhibit reduced leaf post-harvest water loss, and could provide the foundation for selective breeding of improved cultivars. PMID:20580887

  11. Direct investigations on strain-induced cold crystallization behavior and structure evolutions in amorphous poly(lactic acid) with SAXS and WAXS measurements

    DEFF Research Database (Denmark)

    Zhou, Chengbo; Li, Hongfei; Zhang, Wenyang;

    2016-01-01

    in strain-induced crystallization behavior of amorphous PLA within 70-90 degrees C can be attributed to the competition between chain orientation caused by stretching and chain relaxation. It was proposed that the strain-induced mesocrystal/crystal and the lamellae are formed from the mesophase originally......Strain-induced cold crystallization behavior and structure evolution of amorphous poly(lactic acid) (PLA) stretched within 70-90 degrees C were investigated via in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements as well as differential...

  12. Synchrotron-based crystal structure, associated morphology of snail and bivalve shells by X-ray diffraction

    Science.gov (United States)

    Rao, D. V.; Gigante, G. E.; Kumar, Y. Manoj; Cesareo, R.; Brunetti, A.; Schiavon, N.; Akatsuka, T.; Yuasa, T.; Takeda, T.

    2016-10-01

    Synchrotron-based high-resolution X-ray powder diffraction spectra from the body parts of a snail and bivalve (CaCO3), have been recorded with Pilatus area detector. Experiments were performed at Desy, Hamburg, Germany, utilizing the Resonant and Diffraction beamline (P9), with 15 keV X-rays (λ=0.82666 Å). The external shell of these living organisms, is composed of calcium carbonate, which carries strong biological signal. It consists of some light elements, such as, Ca, C and O, which constitute part of the soft tissue and other trace elements. The knowledge of these diffraction patterns and hence the understanding of structures at molecular level are enormous. The application of synchrotron radiation to powder diffraction is well suited for samples of biological nature via changes in their patterns and also to investigate crystallographic phase composition. With the use of Rietveld refinement procedure, to the high-resolution diffraction spectra, we were able to extract the lattice parameters of orthorhombic polymorph of CaCO3, the most abundant mineral produced by these living organisms. The small size of the crystallite is a very important factor related to the biological structure. The natural model presents a combination of organic and inorganic phases with nanometer size. For the present study, we also used the scanning electron microscopy (SEM) to explore the associated morphology of the snail and bivalve.

  13. Fatigue crack growth behavior of a new single crystal nickel-based superalloy (CMSX-4) at 650 C

    International Nuclear Information System (INIS)

    CMSX-4 is a recently developed rhenium containing single crystal nickel-based superalloy. This alloy has potential applications in many critical high-temperature applications such as turbine blades, rotors, nuclear reactors, etc. The fatigue crack growth rate and the fatigue threshold data of this material is extremely important for accurate life prediction, as well as failure safe design, at elevated temperatures. In this paper, the fatigue crack growth behavior of CMSX-4 has been studied at 650 C. The investigation also examined the influence of γ' precipitates (size and distribution) on the near-threshold fatigue crack growth rate and the fatigue threshold. The influence of load ratio on the fatigue crack growth rate and the fatigue threshold was also examined. Detailed fractographic studies were carried out to determine the crack growth mechanism in fatigue in the threshold region. Compact tension specimens were prepared from the single crystal nickel-based superalloy CMSX-4 with [001] orientation as the tensile loading axis direction. These specimens were given three different heat treatments to produce three different γ' precipitate sizes and distributions. Fatigue crack growth behavior of these specimens was studied at 650 C in air. The results of the present investigation indicate that the near-threshold fatigue crack growth rate decreases and that the fatigue threshold increases with an increase in the γ' precipitate size at 650 C. The fatigue threshold decreased linearly with an increase in load ratio. Fractographs at 650 C show a stage 2 type of crack growth along {100} type of crystal planes in the threshold region, and along {111} type of crystal planes in the high ΔK region

  14. Theory of mind mediates the prospective relationship between abnormal social brain network morphology and chronic behavior problems after pediatric traumatic brain injury.

    Science.gov (United States)

    Ryan, Nicholas P; Catroppa, Cathy; Beare, Richard; Silk, Timothy J; Crossley, Louise; Beauchamp, Miriam H; Yeates, Keith Owen; Anderson, Vicki A

    2016-04-01

    Childhood and adolescence coincide with rapid maturation and synaptic reorganization of distributed neural networks that underlie complex cognitive-affective behaviors. These regions, referred to collectively as the 'social brain network' (SBN) are commonly vulnerable to disruption from pediatric traumatic brain injury (TBI); however, the mechanisms that link morphological changes in the SBN to behavior problems in this population remain unclear. In 98 children and adolescents with mild to severe TBI, we acquired 3D T1-weighted MRIs at 2-8 weeks post-injury. For comparison, 33 typically developing controls of similar age, sex and education were scanned. All participants were assessed on measures of Theory of Mind (ToM) at 6 months post-injury and parents provided ratings of behavior problems at 24-months post-injury. Severe TBI was associated with volumetric reductions in the overall SBN package, as well as regional gray matter structural change in multiple component regions of the SBN. When compared with TD controls and children with milder injuries, the severe TBI group had significantly poorer ToM, which was associated with more frequent behavior problems and abnormal SBN morphology. Mediation analysis indicated that impaired theory of mind mediated the prospective relationship between abnormal SBN morphology and more frequent chronic behavior problems. Our findings suggest that sub-acute alterations in SBN morphology indirectly contribute to long-term behavior problems via their influence on ToM. Volumetric change in the SBN and its putative hub regions may represent useful imaging biomarkers for prediction of post-acute social cognitive impairment, which may in turn elevate risk for chronic behavior problems. PMID:26796967

  15. Theory of mind mediates the prospective relationship between abnormal social brain network morphology and chronic behavior problems after pediatric traumatic brain injury.

    Science.gov (United States)

    Ryan, Nicholas P; Catroppa, Cathy; Beare, Richard; Silk, Timothy J; Crossley, Louise; Beauchamp, Miriam H; Yeates, Keith Owen; Anderson, Vicki A

    2016-04-01

    Childhood and adolescence coincide with rapid maturation and synaptic reorganization of distributed neural networks that underlie complex cognitive-affective behaviors. These regions, referred to collectively as the 'social brain network' (SBN) are commonly vulnerable to disruption from pediatric traumatic brain injury (TBI); however, the mechanisms that link morphological changes in the SBN to behavior problems in this population remain unclear. In 98 children and adolescents with mild to severe TBI, we acquired 3D T1-weighted MRIs at 2-8 weeks post-injury. For comparison, 33 typically developing controls of similar age, sex and education were scanned. All participants were assessed on measures of Theory of Mind (ToM) at 6 months post-injury and parents provided ratings of behavior problems at 24-months post-injury. Severe TBI was associated with volumetric reductions in the overall SBN package, as well as regional gray matter structural change in multiple component regions of the SBN. When compared with TD controls and children with milder injuries, the severe TBI group had significantly poorer ToM, which was associated with more frequent behavior problems and abnormal SBN morphology. Mediation analysis indicated that impaired theory of mind mediated the prospective relationship between abnormal SBN morphology and more frequent chronic behavior problems. Our findings suggest that sub-acute alterations in SBN morphology indirectly contribute to long-term behavior problems via their influence on ToM. Volumetric change in the SBN and its putative hub regions may represent useful imaging biomarkers for prediction of post-acute social cognitive impairment, which may in turn elevate risk for chronic behavior problems.

  16. Electrochemical quartz crystal microbalance study on the two-electrode-system cyclic voltammetric behavior of Prussian blue films

    Institute of Scientific and Technical Information of China (English)

    TAN YueMing; XIE QingJi; HUANG JinHua; CHEN DaiWu; CHEN Xin; TU XinMan; LI YunLong; GE Bin; YAO ShouZhuo

    2008-01-01

    A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt's salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.Prussian blue (PB), two-electrode liquid#solid-state cyclic voltammetric behavior, two-channel electrochemical quartz crystal

  17. The crystal structure and morphology of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) p-xylene solvate: a joint experimental and simulation study.

    Science.gov (United States)

    Shen, Fanfan; Lv, Penghao; Sun, Chenghui; Zhang, Rubo; Pang, Siping

    2014-01-01

    The crystal structure of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaiso-wurtzitane (CL-20) p-xylene solvate, and the solvent effects on the crystal faces of CL-20 were studied through a combined experimental and theoretical method. The properties were analyzed by thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).The growth morphology of CL-20p-xylene solvate crystal was predicted with a modified attachment energy model. The crystal structure of CL-20p-xylene solvate belonged to the Pbca space group with the unit cell parameters, a=8.0704(12) Å, b=13.4095(20) Å, c=33.0817(49) Å, and Z=4, which indicated that the p-xylene solvent molecules could enter the crystal lattice of CL-20 and thus the CL-20 p-xylene solvate is formed. According to the solvent-effected attachment energy calculations, (002) and (11-1) faces should not be visible at all, while the percentage area of the (011) face could be increased from 7.81% in vacuum to 12.51% in p-xylene solution. The predicted results from the modified attachment energy model agreed very well with the observed morphology of crystals grown from p-xylene solution. PMID:25401400

  18. The Dynamic Behaviors of Single Crystal RDX Under Ramp Wave Loading to 15GPa

    Science.gov (United States)

    Wang, Guiji; Cai, Jintao; Zhao, Jianheng; Zhao, Feng; Wu, Gang; Tan, Fuli; Sun, Chengwei

    Based on high pulsed power generator CQ-4, the single crystal RDX explosive was researched along different crystal orientations under ramp wave loadings up to 15 GPa. The typical three-wave structures were obtained by means of laser interferometry PDV, which show the elastic-plastic transition and α to γ phase transition. The ramp elastic limit (REL) and yield strength of RDX along 210 and 100 crystal orientations were respectively calculated and the resuts show obvious effects of crystal orientaions for RDX. The ramp elastic limit σIEL of RDX along 210 orientation is 0.688-0.758GPa, and the σIEL of RDX along 100 is 1.039 -1.110 GPa. The α to γ phase transformation characteristics were also analyzed based on the experimental data. The initial phase transition pressure for the two crystal orientation of RDX are about 3.5 to 4 GPa, which agree well with the data of about 4-5GPa given by MD simulation. The data directly validate the results given by Raman Spectrum under shock compression and static high pressure, which couldn't be observed by wave profiles. The experimental data can be used to verify and validate the new models of RDX under dynamic loading. Supported by NSFC of China under Contract No.11327803 and 11176002

  19. Effect of martensite morphology and volume fraction on strain hardening and fracture behavior of martensite–ferrite dual phase steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiecen [State Key Laboratory of Rolling and Automation, Northeastern University, 3-11 Wenhua Road, Shenyang 110819 (China); Di, Hongshuang, E-mail: dhshuang@mail.neu.edu.cn [State Key Laboratory of Rolling and Automation, Northeastern University, 3-11 Wenhua Road, Shenyang 110819 (China); Deng, Yonggang [State Key Laboratory of Rolling and Automation, Northeastern University, 3-11 Wenhua Road, Shenyang 110819 (China); Misra, R.D.K. [Department of Metallurgical and Materials Engineering and Center for Structural and Functional Materials Research and Innovation, University of Texas at El Paso, 500 W. University Avenue, El Paso, TX 79968 (United States)

    2015-03-11

    Two different morphologies of martensite in dual phase (DP) steel were obtained using two different processing routes. In one case, intermediate quenching (IQ) was adapted, where DP steel was water-quenched to obtain martensite phase, followed by inter-critical annealing. In the second case, the steel was cold rolled, followed by inter-critical annealing (CR-IA). For IQ and CR-IA steels, the inter-critical temperatures varied from 750 °C to 850 °C to obtain different volume fractions of martensite. An understanding of structure–property was obtained using a combination of scanning electron microscope (SEM), transmission electron microscope (TEM), and tensile tests. It was observed that fibrous martensite presented in IQ samples, gradually transformed to blocky martensite with increase in inter-critical temperature, resembling the CR-IA steels. The fibrous martensite encouraged martensite cracking, however, the martensite cracking was dramatically decreased in the IQ samples with increase in martensite fraction. The strain hardening behavior studied using the differential C–J model indicated multistage depending on the fraction of martensite. The low volume fraction of martensite in the DP steel provided high ductility–toughness combination and improved strain hardening ability due to the presence of soft ferrite phase in DP steel. Fibrous martensite in DP steel resulted in less strain hardening than blocky martensite, prior to exceeding a threshold volume fraction. The threshold value was significantly smaller for DP steel with blocky martensite.

  20. Effect of martensite morphology and volume fraction on strain hardening and fracture behavior of martensite–ferrite dual phase steel

    International Nuclear Information System (INIS)

    Two different morphologies of martensite in dual phase (DP) steel were obtained using two different processing routes. In one case, intermediate quenching (IQ) was adapted, where DP steel was water-quenched to obtain martensite phase, followed by inter-critical annealing. In the second case, the steel was cold rolled, followed by inter-critical annealing (CR-IA). For IQ and CR-IA steels, the inter-critical temperatures varied from 750 °C to 850 °C to obtain different volume fractions of martensite. An understanding of structure–property was obtained using a combination of scanning electron microscope (SEM), transmission electron microscope (TEM), and tensile tests. It was observed that fibrous martensite presented in IQ samples, gradually transformed to blocky martensite with increase in inter-critical temperature, resembling the CR-IA steels. The fibrous martensite encouraged martensite cracking, however, the martensite cracking was dramatically decreased in the IQ samples with increase in martensite fraction. The strain hardening behavior studied using the differential C–J model indicated multistage depending on the fraction of martensite. The low volume fraction of martensite in the DP steel provided high ductility–toughness combination and improved strain hardening ability due to the presence of soft ferrite phase in DP steel. Fibrous martensite in DP steel resulted in less strain hardening than blocky martensite, prior to exceeding a threshold volume fraction. The threshold value was significantly smaller for DP steel with blocky martensite

  1. Effects of composition and temperature on the large-field behavior of [001]C relaxor single crystals.

    Science.gov (United States)

    Gallagher, John; Lynch, Christopher; Tian, Jian

    2014-12-01

    The compositional dependence of the large-field behavior of [001]C-cut relaxor ferroelectric xPb(In1/2Nb1/2) O3-(1-x-y)Pb(Mg1/3Nb2/3)O3-yPbTiO3 (PIN-PMN-PT) single crystals that are on the rhombohedral side of the morphotropic phase boundary was characterized under electrical, mechanical, and thermal loading. The effects of varying the concentrations of PIN and PT are discussed. Composition was found to impact the material constants and the field-induced phase transformation threshold in the piezoelectric d333-mode configuration. PMID:25474790

  2. Adaptive Optics with a Liquid-Crystal-on-Silicon Spatial Light Modulator and Its Behavior in Retinal Imaging

    Science.gov (United States)

    Shirai, Tomohiro; Takeno, Kohei; Arimoto, Hidenobu; Furukawa, Hiromitsu

    2009-07-01

    An adaptive optics system with a brand-new device of a liquid-crystal-on-silicon (LCOS) spatial light modulator (SLM) and its behavior in in vivo imaging of the human retina are described. We confirmed by experiments that closed-loop correction of ocular aberrations of the subject's eye was successfully achieved at the rate of 16.7 Hz in our system to obtain a clear retinal image in real time. The result suggests that an LCOS SLM is one of the promising candidates for a wavefront corrector in a prospective commercial ophthalmic instrument with adaptive optics.

  3. Morphological and behavioral development of the piracanjuba larvae Desenvolvimento morfológico e comportamental de larvas de piracanjuba

    Directory of Open Access Journals (Sweden)

    Cláudia Maria Reis Raposo Maciel

    2010-05-01

    Full Text Available The objective of this work was to study the morphologic development and the swimming and feeding behaviors of piracanjuba larvae, Brycon orbignyanus Valenciennes (1849 (Characiformes, Characidae, Bryconinae, during the period from zero to 172 hours after hatching (standard length = 3.62 - 11.94 mm. The morphological analyses were accomplished by using a trinocular stereo microscope, while the behavioral analyses were performed through periodic observations. In 28 hours after hatching, the larvae (standard length = 6.25 ± 0.13 mm showed the following structural and behavioral characteristics that made them become active predators able to overcome a larval critical phase, the beginning of exogenous feeding: presence of pigmented eyes, terminal and wide mouth, developed oral dentition, developing digestive tube, yolk sac reduction, fins and swim bladder formation, horizontal swimming, cannibalism, and predation. Intense cannibalism among larvae was verified from 26 to 72 hours. At the end of the metamorphosis - 172 hours after hatching - the larvae measuring 11.94 + 0.80 mm in standard length presented a flexed notochord, caudal fin bifurcation, dorsal and anal fin formation, synchronized movements, and formation of shoals, characteristics that together allow enhanced perception and locomotio in exploration of the environment, determining the best moment for transfering to the fishponds. New studies can contribute to commercial fish farming by improving feeding management, performance, survival, and productivity of this species.Objetivou-se estudar o desenvolvimento morfológico e os comportamentos natatório e alimentar de larvas de piracanjuba, Brycon orbignyanus Valenciennes (1849 (Characiformes, Characidae, Bryconinae no período de 0 a 172 horas após a eclosão (comprimento-padrão = 3,62 - 11,94 mm. As análises morfológicas foram realizadas com auxílio de um microscópio estereoscópico trinocular e as comportamentais, por meio de

  4. High temperature oxidation behavior of aluminide on a Ni-based single crystal superalloy in different surface orientations

    Institute of Scientific and Technical Information of China (English)

    Fahamsyah H.Latief; Koji Kakehi; El-Sayed M.Sherif

    2014-01-01

    An investigation on oxidation behavior of coated Ni-based single crystal superalloy in different surface orientations has been carried out at 1100 1C. It has been found that the {100} surface shows a better oxidation resistance than the {110} one, which is attributed that the {110}surface had a slightly higher oxidation rate when compared to the {100} surface. The experimental results also indicated that the anisotropic oxidation behavior took place even with a very small difference in the oxidation rates that was found between the two surfaces. The differences of the topologically close packed phase amount and its penetration depth between the two surfaces, including the ratio of α-Al2O3 after 500 h oxidation, were responsible for the oxidation anisotropy.

  5. Shear and Rapeseed Oil Addition Affect the Crystal Polymorphic Behavior of Milk Fat

    DEFF Research Database (Denmark)

    Kaufmann, Niels; Kirkensgaard, Jacob Judas Kain; Andersen, Ulf;

    2013-01-01

    The effect of shear on the crystallization kinetics of anhydrous milk fat (AMF) and blends with 20 and 30 % w/w added rapeseed oil (RO) was studied. Pulse 1H NMR was used to follow the a to b0 polymorphic transition. The NMR method was confirmed and supported by SAXS/WAXS experiments. Samples were...

  6. Thermodynamic equilibrium, metastable zone widths, and nucleation behavior in the cooling crystallization of gestodene-ethanol systems

    Science.gov (United States)

    Wang, Li-yu; Zhu, Liang; Yang, Li-bin; Wang, Yan-fei; Sha, Zuo-liang; Zhao, Xiao-yu

    2016-03-01

    A systematic investigation of nucleation behavior for the batch cooling crystallization of unseeded gestodene-ethanol solutions was carried out. The solubilities of the two polymorphs (forms I and II) of gestodene in ethanol were gravimetrically measured between 268.15 and 333.15 K under atmospheric pressure of 0.10 MPa. In addition, the metastable zone widths (MSZWs) of the gestodene-ethanol solutions were determined by the polythermal method combined with the focused beam reflectance measurement (FBRM®) technique. Moreover, polymorphic forms of the grown crystals were identified by X-ray powder diffraction (XRD) and optical microscope. Experimental results indicated that the measured MSZWs were dependent on numerous technological parameters, including cooling rate, saturation temperature, and agitation intensity. With variation of the nucleation temperature and cooling rate, forms I, II, and a mixture of the two forms were crystallized from ethanol solution. The nucleation kinetic parameters were estimated from MSZW data using the self-consistent Nývlt-like approach. Due to the high solubility of form I in ethanol at the corresponding temperature range, the stronger solute-solvent interactions confirmed that the nucleation of form I had a greater activation energy than that of form II.

  7. Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

    International Nuclear Information System (INIS)

    Linking of trinuclear pivalate Fe2NiO(Piv)6 (Piv=O2CC(CH3)3) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe2NiO(Piv)6(L)·Solv, which was characterized in two forms: DMSO solvate Fe2NiO(Piv)6(L)(DMSO)·2.5DMSO (1) or water solvate Fe2NiO(Piv)6(L)(H2O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe2NiO(Piv)6(L) was confirmed by the measurements of N2 and H2 adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe2NiO(Piv)6(L)(H2O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics

  8. Flow-induced crystallization in isotactic polypropylene

    Science.gov (United States)

    Hamad, Fawzi Ghassan

    Brief intervals of strong flow stretch chains in a semicrystalline polymer melt, which results in an increase in the nuclei number density and a transformation of the crystal structure. This flow-induced crystallization (FIC) phenomenon is explored in this study using highly isotactic polypropylene (iPP) samples. Using one synthesized and five commercial linear isotactic polypropylene samples, we investigate the FIC behavior by imposing shear onto these samples in a rotational rheometer. Equipped with a good temperature control and flexible shear protocol, we apply different temperature and flow conditions. The magnitude of the FIC effect varies with basic processing parameters (shear rate, specific work, crystallization temperature, and shearing temperature) and material properties (totalistic, molecular weight distribution, and particle concentration in the polymer). The scope of this study is to systematically investigate the influences of these parameters on FIC. The FIC effects that are investigated in this dissertation are: crystallization kinetics, persistence time of flow-induced nuclei, and crystal morphology. The crystallization time was measured in the rheometer by monitoring the onset of crystallization after quenching samples sheared above Tm. These samples were subsequently used to study their flow-induced nuclei persistence time and crystal morphology. The lifetime of flow-induced nuclei was determined by measuring the time required to return from FIC back to quiescent crystallization using a differential scanning calorimeter. The crystal morphology was imaged using polarized optical microscopy and atomic force microscopy. We investigated the influence of specific work on the three FIC characteristics, and found three regimes that are separated by the critical work ( Wc) and the saturation work (Wsat) thresholds. Below the critical work threshold, the morphology is composed of mostly spherulite crystals, which keep a constant volume, and a small

  9. DENDRITE REFINING AND EUTECTIC TRANSFORMATION BEHAVIOR OF NICKEL-BASE SINGLE CRYSTAL (NBSC) SUPERALLOY

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    Because of the low temperature gradient and growth rate, the microstructure of the conventional single crystal superalloy made by HRS processing is coarse dendrite with well developed sidebranches and has serious segregation. With the help of the high temperature gradient directional solidification equipment (HGDS), the solidification cooling rate is greatly increased. Study on microstructure of the Ni-base single crystal superalloy solidified at much higher cooling rate shows that the dendrite arm spacing is highly refined, of which the primary dendrite arm spacing can be made to be 38μm, just as 1/10 as that by conventional HRS processing. With the increase of the cooling rate, the amount of the eutectic increases and then decreases. In the superfine columnar dendrite, the amount of γ/γ′eutectic is much fewer and its size is very small. This is useful to homogenize the microsegregation and improve the property of the material.

  10. The behavior of Er3+ dopants during crystallization in oxyfluoride silicate glass ceramics

    International Nuclear Information System (INIS)

    In this paper, the changes of local environment of Er3+ during heat treatment process have been studied in 50SiO2-45PbF2-5PbO system. The samples were characterized by X-ray diffraction (XRD), absorption spectra, fluorescence decay curves and luminescence spectra. The experimental results indicate that PbF2 crystals were precipitated in the precursor sample. However, a significant fraction of Er3+ remains in the glassy phase. With increasing heat treatment time, the Er3+ in the glass matrix may enter into fluoride nanocrystals gradually. When the heat treatment time reached 15 min, most of the Er3+ ions were incorporated into the fluoride nanocrystals. Based on the experimental analysis, we considered that Er3+ not only act as nucleating agents for the precipitation of crystalline fluoride phase during nucleation process but also enter into nanocrystals during crystals growth process.

  11. Magnetodielectric and Metalomagnetic 1D Photonic Crystals Homogenization: ε-μ Local Behavior

    Directory of Open Access Journals (Sweden)

    J. I. Rodríguez Mora

    2016-01-01

    Full Text Available A theory for calculating the effective optic response of photonic crystals with metallic and magnetic inclusions is reported, for the case when the wavelength of the electromagnetic fields is much larger than the lattice constant. The theory is valid for any type of Bravais lattice and arbitrary form of inclusions in the unitary cell. An equations system is obtained for macroscopic magnetic field and magnetic induction components expanding microscopic electromagnetic fields in Bloch waves. Permittivity and permeability effective tensors are obtained comparing the equations system with an anisotropic nonlocal homogenous medium. In comparison with other homogenization theories, this work uses only two tensors: nonlocal permeability and permittivity. The proposal showed here is based on the use of permeability equations, which are exact and very simple. We present the explicit form of these tensors in the case of binary 1D photonic crystals.

  12. Long-time Behavior for Nonlinear Hydrodynamic System Modeling the Nematic Liquid Crystal Flows

    OpenAIRE

    Wu, Hao

    2009-01-01

    We study a simplified system of the original Ericksen--Leslie equations for the flow of nematic liquid crystals. This is a coupled non-parabolic dissipative dynamic system. We show the convergence of global classical solutions to single steady states as time goes to infinity (uniqueness of asymptotic limit) by using the \\L ojasiewicz--Simon approach. Moreover, we provide an estimate on the convergence rate. Finally, we discuss some possible extensions of the results to certain generalized pro...

  13. Phase Behavior of Mixtures of Low Molecular Weight Nematic Liquid Crystals and Photochemically Crosslinked Polyacrylates

    OpenAIRE

    BEDJAOUI, Lamia; N. BERRIAH; K. BOUDRAA; Bouchaour, T.; MASCHKE, Ulrich

    2010-01-01

    The present work deals with theoretical and experimental studies to explore some physical properties of composite materials made of crosslinked poly(nbutylacrylate) networks and low molecular weight nematic liquid crystals (LCs). The chemically crosslinked polymers were obtained by exposure to UV radiation of initial solutions composed of a reactive monomer, n-butylacrylate, a small amount of a crosslinking agent, hexanedioldiacrylate, and a photoinitiator. To obtain different ...

  14. Visualization of the Crystallization in Foam Extrusion Process

    Science.gov (United States)

    Tabatabaei Naeini, Alireza

    In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

  15. Conducting behavior of chalcopyrite-type CuGaS₂ crystals under visible light.

    Science.gov (United States)

    Cholula-Díaz, Jorge L; Barzola-Quiquia, José; Kranert, Christian; Michalsky, Tom; Esquinazi, Pablo; Grundmann, Marius; Krautscheid, Harald

    2014-10-21

    Millimeter size high quality crystals of CuGaS2 were grown by chemical vapor transport. The highly ordered chalcopyrite structure is confirmed by X-ray diffraction and Raman spectroscopy. According to energy dispersive X-ray spectroscopy the composition of the crystals is very close to the formula CuGaS2. Room temperature photoluminescence measurements indicate the presence of an emission peak at about 2.36 eV that can be related to a donor-acceptor pair transition. The electrical resistance as a function of temperature is very well described by the Mott variable range hopping mechanism. Room temperature complex impedance spectroscopy measurements were performed in the alternating current frequency range from 40 to 10(7) Hz in the dark and under normal light. According to the impedance spectroscopy data the experimental results can be well described by two circuits in series, corresponding to bulk and grain boundary contributions. An unusual positive photoresistance effect is observed in the frequency range between 3 and 30 kHz, which we suggest to be due to intrinsic defects present in the CuGaS2 crystal.

  16. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    International Nuclear Information System (INIS)

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe86B7C7 alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe3C and α-Fe phase impedes the devitrification. • Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity

  17. Orientation dependence of deformation and penetration behavior of tungsten single-crystal rods

    International Nuclear Information System (INIS)

    This paper reports on the performance of tungsten single crystals as kinetic energy penetrator materials that was investigated in a high length-to-diameter (L/D) rod geometry at sub-scale (1/4 geometric scale). The [111]. [110], and [100] crystal orientations were tested in this 74-g LD = 15 geometry penetrator (6.90-mm diameter x 102.5-mm length). Several 93% tungsten alloy and uranium 3/4 titanium rod geometries were also tested to baseline expected performance of typical penetrator material/geometry combinations. Performance was determined for semi-infinite penetration into RHA steel and finite penetration into 76.20-mm RHA steel. Of the orientation tested, the [100] orientation provided the best ballistic results, with superior performance to mass and geometric equivalent 93% tungsten alloy rods. The [100] orientation also provided similar performance to geometric equivalent uranium 3/4 titanium rods. Favorable slip/cleavage during the compressive loading of the penetration process to allow penetrator material flow without large scale plastic deformation, and final shear localization at a favorable angle for easy material flow away from the penetration interface, contribute to the [100] orientation crystals' excellent performance. The net result was less energy expenditure during penetrator flow and, therefore, more energy for deformation of RHA

  18. Synthesis, Crystal Structure and Thermal Behavior of 4,5-Dimethoxy-2-(dinitromethylene)imidazolidine

    Institute of Scientific and Technical Information of China (English)

    WANG Min; XU Kang-zhen; HE Fei; ZHANG Hang; CHEN Yong-shun; SONG Ji-rong; ZHAO Feng-qi

    2012-01-01

    A new energetic material,4,5-dimethoxy-2-(dinitromethylene)imidazolidine(DMDNI),was synthesized by the reaction of 4,5-dihydroxyl-2-(dinitromethylene)-imidazolidine(DDNI) and methanol,and structurally characterized by single crystal X-ray diffraction.DMDNI crystallized in triclinic space group P(1),with crystal data a=0.4324(4) nm,b=1.3599(11) nm,c=1.7503(14) nm,a=77.406(14)°,β=84.494(15)°,γ=87.976(14)°,V=0.9997(14)nm3,Z=4,μ=0.140 mm-1,F(000)=488,Dc=1.556 g/cm3,R1=0.0773 and wR2=0.1574.Thermal decomposition of DMDNI was studied,and its thermal decomposition process was divided into two stages.The first stage was a melting process and the second stage was an exothermic decomposition process.The enthalpy,apparent activation energy and pre-exponential constant of the exothermic decomposition reaction are -491.5 J/g,142.3 kJ/mol and 101424 s-1,respectively.The critical temperature of thermal explosion is 162.47 ℃.DMDNI has a lower thermal stability than DDNI but it is close to that of 4,5-diacetoxyl-2-(dinitromethylene)-imidazolidine(DADNI).

  19. Synergistic Effects of Nucleating Agents and Plasticizers on the Crystallization Behavior of Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Xuetao Shi

    2015-01-01

    Full Text Available The synergistic effect of nucleating agents and plasticizers on the thermal and mechanical performance of PLA nanocomposites was investigated with the objective of increasing the crystallinity and balancing the stiffness and toughness of PLA mechanical properties. Calcium carbonate, halloysite nanotubes, talc and LAK (sulfates were compared with each other as heterogeneous nucleating agents. Both the DSC isothermal and non-isothermal studies indicated that talc and LAK were the more effective nucleating agents among the selected fillers. Poly(D-lactic acid (PDLA acted also as a nucleating agent due to the formation of the PLA stereocomplex. The half crystallization time was reduced by the addition of talc to about 2 min from 37.5 min of pure PLA by the isothermal crystallization study. The dynamic mechanical thermal study (DMTA indicated that nanofillers acted as both reinforcement fillers and nucleating agents in relation to the higher storage modulus. The plasticized PLA studied by DMTA indicated a decreasing glass transition temperature with the increasing of the PEG content. The addition of nanofiller increased the Young’s modulus. PEG had the plasticization effect of increasing the break deformation, while sharply decreasing the stiffness and strength of PLA. The synergistic effect of nanofillers and plasticizer achieved the balance between stiffness and toughness with well-controlled crystallization.

  20. Effect of H{sup +} ion implantation on structural, morphological, optical and dielectric properties of L-arginine monohydrochloride monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Crystal Growth and Thin film Laboratory, Department of Physics, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Babu, R. Ramesh, E-mail: rampap2k@yahoo.co.in [Crystal Growth and Thin film Laboratory, Department of Physics, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Kumar, P. [Inter-University Accelerator Centre, P.O. Box 10502, Aruna Asaf Ali Marg, New Delhi 110067 (India); Bhagvannarayana, G. [Materials Characterization Division, National Physical Laboratory, New Delhi 110012 (India); Ramamurthi, K. [Crystal Growth and Thin film Laboratory, Department of Physics, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India)

    2011-06-15

    L-arginine monohydrochloride monohydrate (LAHCl) single crystals have been implanted with 100 keV H{sup +} ions at different ion fluence ranging from 10{sup 12} to 10{sup 15} ions/cm{sup 2}. Implanted LAHCl single crystals have been investigated for property changes. Crystal surface and crystalline perfection of the pristine and implanted crystals were analyzed by atomic force microscope and high-resolution X-ray diffraction studies, respectively. Optical absorption bands induced by colour centers, refractive index and birefringence, mechanical stability and dielectric constant of implanted crystals were studied at different ion fluence and compared with that of pristine LAHCl single crystal.

  1. Crystallization and Melting Behavior of Linear Polyethylene and Ethylene/Styrene Copolymers and Chain Length Dependence of Spherulitic Growth Rate for Poly(Ethylene Oxide) Fractions

    OpenAIRE

    Huang, Zhenyu

    2004-01-01

    The crystallization and melting behavior of linear polyethylene and of a series of random ethylene/styrene copolymers was investigated using a combination of classical and temperature modulated differential scanning calorimetry. In the case of linear polyethylene and low styrene content copolymers, the temporal evolutions of the melting temperature, degree of crystallinity, and excess heat capacity were studied during crystallization. The following correlations were established: 1) the evolut...

  2. Meek Males and Fighting Females: Sexually-Dimorphic Antipredator Behavior and Locomotor Performance Is Explained by Morphology in Bark Scorpions (Centruroides vittatus)

    OpenAIRE

    Carlson, Bradley E.; McGinley, Shannen; Rowe, Matthew P.

    2014-01-01

    Sexual dimorphism can result from sexual or ecological selective pressures, but the importance of alternative reproductive roles and trait compensation in generating phenotypic differences between the sexes is poorly understood. We evaluated morphological and behavioral sexual dimorphism in striped bark scorpions (Centruroides vittatus). We propose that reproductive roles have driven sexually dimorphic body mass in this species which produces sex differences in locomotor performance. Poor loc...

  3. Comparative analysis of surface wax in mature fruits between Satsuma mandarin (Citrus unshiu) and 'Newhall' navel orange (Citrus sinensis) from the perspective of crystal morphology, chemical composition and key gene expression.

    Science.gov (United States)

    Wang, Jinqiu; Hao, Haohao; Liu, Runsheng; Ma, Qiaoli; Xu, Juan; Chen, Feng; Cheng, Yunjiang; Deng, Xiuxin

    2014-06-15

    Surface wax of mature Satsuma mandarin (Citrus unshiu) and 'Newhall' navel orange (Citrus sinensis) was analysed by crystal morphology, chemical composition, and gene expression levels. The epicuticular and total waxes of both citrus cultivars were mostly composed of aldehydes, alkanes, fatty acids and primary alcohols. The epicuticular wax accounted for 80% of the total wax in the Newhall fruits and was higher than that in the Satsuma fruits. Scanning electron microscopy showed that larger and more wax platelets were deposited on the surface of Newhall fruits than on the Satsuma fruits. Moreover, the expression levels of genes involved in the wax formation were consistent with the biochemical and crystal morphological analyses. These diversities of fruit wax between the two cultivars may contribute to the differences of fruit postharvest storage properties, which can provide important information for the production of synthetic wax for citrus fruits.

  4. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.D., E-mail: fanxd@seu.edu.cn; Shen, B.L., E-mail: blshen@seu.edu.cn

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe{sub 86}B{sub 7}C{sub 7} alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe{sub 3}C and α-Fe phase impedes the devitrification. • Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity.

  5. Chaotic orientational behavior of a nematic liquid crystal subjected to a steady shear flow.

    Science.gov (United States)

    Rienäcker, Götz; Kröger, Martin; Hess, Siegfried

    2002-10-01

    Based on a relaxation equation for the second rank alignment tensor characterizing the molecular orientation in liquid crystals, we report on a number of symmetry-breaking transient states and simple periodic and irregular, chaotic out-of-plane orbits under steady flow. Both an intermittency route and a period-doubling route to chaos are found for this five-dimensional dynamic system in a certain range of parameters (shear rate, tumbling parameter at isotropic-nematic coexistence, and reduced temperature). A link to the corresponding rheochaotic states, present in complex fluids, is made. PMID:12443167

  6. The growth of a single crystal of Sr3CuIrO6 and its magnetic behavior compared to polycrystals

    Indian Academy of Sciences (India)

    Asad Niazi; P L Paulose; E V Sampathkumaran; Ute Ch Rodewald; W Jeitschko

    2002-05-01

    We have grown single crystals of the psuedo-one-dimensional compound Sr3CuIrO6, a K4CdCl6-derived monoclinic structure with Cu–Ir chains along the [101] direction. We present the ac and dc magnetization behavior of the single crystals in comparison with that of the polycrystalline form reported earlier. There is a distinct evidence for at least two magnetic transitions, at 5 K (1) and 19 K (2), with different relative magnitudes in the single and polycrystals. The low temperature magnetic relaxation behavior of both the forms is found to be widely different, exhibiting unexpected time dependence.

  7. Macroscopic behavior of ferrocholesteric liquid crystals and ferrocholesteric gels and elastomers.

    Science.gov (United States)

    Brand, Helmut R; Fink, Alexander; Pleiner, Harald

    2015-06-01

    We study the influence of macroscopic chirality on the macroscopic properties of superparamagnetic liquid crystals and gels. Specifically we derive macroscopic dynamic equations for ferrocholesteric low molecular weight (LMW) liquid crystals and for ferrocholesteric gels and elastomers in the local description using the director field as macroscopic variable. The magnetization is treated as a macroscopic dynamic degree of freedom and its coupling to all other macroscopic variables is examined in detail. We incorporate into our dynamic analysis terms that are linear in a magnetic field giving rise to a number of cross-coupling terms not possible otherwise. A number of properties that are unique to the class of systems studied arise. As an example for a static property we find a term in the generalized energy which is linear in the electric field and quadratic in the magnetic field. We find that applying a magnetic field to a ferrocholesteric can lead to reversible electric currents, heat currents and concentration currents, which change their sign with a sign change of macroscopic chirality. As an example of a rather intriguing dissipative dynamic contribution we point out that for ferrocholesterics and for ferrocholesteric gels and elastomers in a magnetic field extensional flow leads to electric and heat currents. PMID:26123769

  8. The behavior of Er{sup 3+} dopants during crystallization in oxyfluoride silicate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lin Lejing [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China); Ren Guozhong, E-mail: rgz76@sohu.co [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China); Chen Minpeng; Liu Yang [Institute of Modern Physics, Xiangtan University, Xiangtan 411105 (China); Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan 411105 (China)

    2009-11-03

    In this paper, the changes of local environment of Er{sup 3+} during heat treatment process have been studied in 50SiO{sub 2}-45PbF{sub 2}-5PbO system. The samples were characterized by X-ray diffraction (XRD), absorption spectra, fluorescence decay curves and luminescence spectra. The experimental results indicate that PbF{sub 2} crystals were precipitated in the precursor sample. However, a significant fraction of Er{sup 3+} remains in the glassy phase. With increasing heat treatment time, the Er{sup 3+} in the glass matrix may enter into fluoride nanocrystals gradually. When the heat treatment time reached 15 min, most of the Er{sup 3+} ions were incorporated into the fluoride nanocrystals. Based on the experimental analysis, we considered that Er{sup 3+} not only act as nucleating agents for the precipitation of crystalline fluoride phase during nucleation process but also enter into nanocrystals during crystals growth process.

  9. Models for Copper Dynamic Behavior in Doped Cadmium dl-Histidine Crystals: Electron Paramagnetic Resonance and Crystallographic Analysis.

    Science.gov (United States)

    Colaneri, Michael J; Teat, Simon J; Vitali, Jacqueline

    2015-11-12

    Electron paramagnetic resonance and crystallographic studies of copper-doped cadmium dl-histidine, abbreviated as CdDLHis, were undertaken to gain further understanding on the relationship between site structure and dynamic behavior in biological model complexes. X-ray diffraction measurements determined the crystal structure of CdDLHis at 100 and 298 K. CdDLHis crystallizes in the monoclinic space group P21/c with two cadmium complexes per asymmetric unit. In each complex, the Cd is hexacoordinated to two histidine molecules. Both histidines are l in one complex and d in the other. Additionally, each complex contains multiple waters of varying disorder. Single crystal EPR spectroscopic splitting (g) and copper hyperfine (A(Cu)) tensors at room temperature (principal values: g = 2.249, 2.089, 2.050; A(Cu) = -453, -30.5, -0.08 MHz) were determined from rotational experiments. Alignments of the tensor directions with the host structure were used to position the copper unpaired dx(2)-y(2) orbital in an approximate plane made by four proposed ligand atoms: the N-imidazole and N-amino of one histidine, and the N-amino and O-carboxyl of the other. Each complex has two such planes related by noncrystallographic symmetry, which make an angle of 65° and have a 1.56 Å distance between their midpoints. These findings are consistent with three interpretations that can adequately explain previous temperature-dependent EPR powder spectra of this system: (1) a local structural distortion (static strain) at the copper site has a temperature dependence significant enough to affect the EPR pattern, (2) the copper can hop between the two sites in each complex at high temperature, and (3) there exists a dynamic Jahn-Teller effect involving the copper ligands. PMID:26501364

  10. Synthesis, Crystal Structure and Catalytic Behavior of 1-Ethyl-3-benyl-imidazolyl Tetranuclear N-Heterocyclic Carbene Silver Bromide

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Guo; SU Zhi-Xian; BIAN Qing-Quan; LIU Si-Man; LIU Ting

    2012-01-01

    The title complex [Ag(carbene)2]2[Ag2Br4] has been synthesized by the reaction of Ag2O with 1-ethyl-3-benyl-imidazolium bromide in DMSO at room temperature, and characterized by elemental analysis, 1H NMR and single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P with a = 10.1597(10), b =11.0646(11), c = 13.0245(14) , α = 102.230(2), β = 90.606, γ = 113.9250(10)o, V = 1300.3(2) 3, Mr = 748.06, Z = 2, Dc = 1.911 g/cm3, μ(MoKα) = 4.60 mm-1 and F(000) = 728. The structure was refined to R = 0.0316 and wR = 0.0835 for 3744 observed reflections with I 〉 2σ(I). The title compound crystallizes as a centrosymmetric tetranuclear compound. One half of the molecule comprises the asymmetric unit of the structure. The Ag(1) atom is nearly linear or T-shaped when the Ag(1)-Ag(2) interaction is taken into consideration, which is bi-coordinated by two carbene carbon atoms. The Ag(2) atom adopts tetrahedral geometry. The catalytic behavior of the title complex has been investigated, and the results indicate it has a highly catalytic activation for L-lactide polymerization.

  11. Magnetization behavior of RE123 bulk magnets bearing twin seed-crystals in pulsed field magnetization processes

    Science.gov (United States)

    Oka, T.; Miyazaki, T.; Ogawa, J.; Fukui, S.; Sato, T.; Yokoyama, K.; Langer, M.

    2016-02-01

    Melt-textured Y-Ba-Cu-O high temperature superconducting bulk magnets were fabricated by the cold seeding method with using single or twin-seed crystals composed of Nd-Ba-Cu-O thin films on MgO substrates. The behavior of the magnetic flux penetration into anisotropic-grown bulk magnets thus fabricated was precisely evaluated during and after the pulsed field magnetization operated at 35 K. These seed crystals were put on the top surfaces of the precursors to grow large grains during the melt-processes. Although we know the magnetic flux motion is restricted by the enhanced pinning effect in temperature ranges lower than 77 K, we observed that flux invasion occurred at applied fields of 3.3 T when the twin seeds were used. This is definitely lower than those of 3.7 T when the single-seeds were employed. This means that the magnetic fluxes are capable of invading into twin-seeded bulk magnets more easily than single-seeded ones. The twin seeds form the different grain growth regions, the narrow-GSR (growth sector region) and wide-GSR, according to the different grain growth directions which are parallel and normal to the rows of seed crystals, respectively. The invading flux measurements revealed that the magnetic flux invades the sample from the wide-GSR prior to the narrow-GSR. It suggests that such anisotropic grain growth leads to different distributions of pinning centers, variations of J c values, and the formation of preferential paths for the invading magnetic fluxes. Using lower applied fields definitely contributed to lowering the heat generation during the PFM process, which, in turn, led to enhanced trapped magnetic fluxes.

  12. Deformation behavior of Cu-12wt%AI alloy wires with continuous columnar crystals in dieless drawing process

    Institute of Scientific and Technical Information of China (English)

    LIU XueFeng; WU YuHui; XIE JianXin

    2009-01-01

    The microstructure and mechanical properties of Cu-12wt%AI alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0-1.4 mm/s and deformation temperature of 600-900℃ were analyzed,and deformation behavior of the alloy during dieless drawing forming was experimentally investigated.The results showed that in the above-mentioned conditions,recrystallization phenomenon was not found during dieless drawing forming.When a drawing speed of 1.0 mm/s was used,the grain boundaries were out of straight gradually with increasing deformation temperature from 600℃ to 900℃,and tensile strength of the dieless drawn Cu-12wt%AI alloy wires increased while elongations decreased with increasing deformation temperature.At drawing speed of 1.1-1.2 mm/s and deformation temperature of 600℃,the effect of dieless drawing forming process on the microstructure of the alloy was inconspicuous,and when drawing speed was up to 1.3-1.4 mm/s,the grain boundaries of continuous columnar crystals became zigzag while there was little effect of drawing speed of 1.1-1.4 mm/s on the elongation and tensile strength of the alloy wires.

  13. Deformation behavior of Cu-12wt%Al alloy wires with continuous columnar crystals in dieless drawing process

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The microstructure and mechanical properties of Cu-12wt%Al alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0―1.4 mm/s and deformation temperature of 600―900℃ were analyzed, and deformation behavior of the alloy during dieless drawing forming was experimentally investigated. The results showed that in the abovemen-tioned conditions, recrystallization phenomenon was not found during dieless drawing forming. When a drawing speed of 1.0 mm/s was used, the grain boundaries were out of straight gradually with increasing deformation temperature from 600℃ to 900℃, and tensile strength of the dieless drawn Cu-12wt%Al alloy wires increased while elongations decreased with increasing deformation temperature. At drawing speed of 1.1―1.2 mm/s and deformation temperature of 600℃, the effect of dieless drawing forming process on the microstructure of the alloy was inconspicuous, and when drawing speed was up to 1.3―1.4 mm/s, the grain boundaries of continuous columnar crystals became zigzag while there was little effect of drawing speed of 1.1―1.4 mm/s on the elongation and tensile strength of the alloy wires.

  14. Control of the anchoring behavior of polymer-dispersed liquid crystals: effect of branching in the side chains of polyacrylates.

    Science.gov (United States)

    Zhou, Jian; Collard, David M; Park, Jung O; Srinivasarao, Mohan

    2002-08-28

    A temperature-driven anchoring transition in a polymer/nematic fluid composite that is far from the bulk nematic-isotropic transition temperature is reported. A series of poly(methylheptyl acrylates) were studied to probe the subtle effects of the side chain structure of the polymer on control of the anchoring. A polymer-dispersed liquid crystal film made from TL205 and 1-methylheptyl acrylate shows only planar anchoring over the temperature range studied, while the films made from TL205 and each of the other methylheptyl acrylates or n-heptyl acrylate show the homeotropic-to-planar anchoring transition at temperatures between 70 and 78 degrees C. An interfacial model is proposed in which the different conformation of the side chains is suggested as the cause for the dramatic difference in the observed anchoring behavior. PMID:12188649

  15. Low-temperature dielectric behavior of disordered and ordered langasite family single crystals LGS, LGT, SNGS and STGS

    Science.gov (United States)

    Smirnova, E.; Sotnikov, A.; Schmidt, H.; Weihnacht, M.; Sakharov, S.

    2015-10-01

    Dielectric measurements of disordered La3Ga5SiO14 (LGS), La3Ga5,5Ta0,5O14 (LGT) and ordered Sr3NbGa3Si2O14 (SNGS), Sr3TaGa3Si2O14 (STGS) single crystals of the langasite family performed at frequencies from 10 Hz to 1 MHz at temperatures between 4.2 and 300 K are reported. Temperature dependences of dielectric permittivity ε33 and ε11 are obtained. It is shown that ε33 in LGS and LGT exhibits incipient ferroelectric-like behavior. SNGS and STGS demonstrate ordinary dielectric temperature dependences as dielectric permittivity decreases down to helium temperatures.

  16. Stress-induced deformation at Ap~Mp and thermal cycling behavior of Cu-Al-Ni single crystals

    Institute of Scientific and Technical Information of China (English)

    陈庆福; 蔡伟; 赵连城

    2001-01-01

    Stress-induced deformation in Ap~Mp and concomitant shape recovery behavior of Cu-13.4Al-4.0Ni single crystals were studied. Abnormal high stress-induced deformation exists in Ap~Mp under the conditions of either heating with load or cooling with load. The recovered deformation is successively composed of four parts, the recoveries from superelasticity, normal reverse transformation, thermally activated reverse transformation of partially stabilized martensite and reverse transformation of stabilized martensite by over-heating. With increasing cycling number, the recovery part from normal reverse transformation decreases, while that from reverse transformation of stabilized martensite by over-heating increases, which shows a typical stabilization of martensite.

  17. NUMERICAL STUDY OF THE NOTCH EFFECT ON THE CREEP BEHAVIOR AND LIFE OF NICKEL-BASE SINGLE CRYSTAL SUPERALLOYS

    Institute of Scientific and Technical Information of China (English)

    Q.M. Yu; Z.F. Yue

    2004-01-01

    Numerical calculations of creep damage development and life behavior of circular notched specimens of nickel-base single crystal had been performed. The creep stress distributions depend on the specimen geometry. For a small notch radius, von Mises stress has an especial distribution. The damage distribution is greatly influenced by the notch depth, notch radius as well as notch type. The creep crack initiation place is different for each notched specimen. The characteristics of notch strengthening and notch weakening depend on the notch radius and notch type. For the same notch type,the creep rupture lives decrease with the decreasing of notch radius. A creep life model has been presented for the multiaxial stress states based on the crystallographic slip system theory.

  18. 高真空强静电场下聚合物薄膜微晶生长形态转变研究%STUDIES ON THE MORPHOLOGY TRANSITION OF MICRO-CRYSTAL GROWTH IN POLYMER FILMS IN HIGH VACUUM AND STRONG ELECTROSTATIC FIELD

    Institute of Scientific and Technical Information of China (English)

    肖学山; 徐晖; 董远达; 乔秀颖; 莫志深; 王献红; 王庆

    2001-01-01

    The morphology of films of isotactic polypropylene poly(3-dodecylthiophene) and iPP/P3DDT blend formed in electrostatic fields has been investigated by using scanning electron microscope. The experiment results show that the micro-crystal morphology of polymer films was strongly dependent on electrostatic fields. It was found that the effect of the electrostatic field led to the formation of dendrite crystals aligned in the field direction,and some branches of P3DDT ruptured. However,the micro-crystals in these films grew into spherulites without electrostatic field,and have no crystal orientation.

  19. Phase Behavior and Crystal Structure of Perovskite-Type Rare Earth Complex Oxides

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Several compounds of rare earth complex oxides containing manganese and titanium were synthesized in Ar, and their crystal structures were analyzed by powder X-ray diffraction data and Rietveld method. Structures of A0.67Ln0.33Mn0.33Ti0.67O3 (A=Ca or Sr and Ln=rare earth) were found to have orthorhombic symmetry with the space group Pnma, and their interatomic distances and bond angles were obtained. This space group was also derived from electron microscopic study. Electrical conductivity of Ca0.67Ln0.33Mn0.33Ti0.67O3 for several rare earth elements showed a semiconducting property with the activation energy of 0.4 eV. Some of these compounds of the strontium system show the antiferromagnetic properties below 10 K.

  20. Crystallization Behavior of Anatase Films in Applied Electric Field Heating Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this research the TiO2 thin films were prepared by sol-gel dip coating. The crystallization of the films in the applied electric field heating process was thoroughly studied by many technique, differential thermal analysis (DTA), Raman spectroscopy and atomic force microscope (AFM). Furthermore the phase formation, microstructure and photo-catalytic activity of TiO2 film were studied under the condition of an electric field heating-treatment. It is found that the existence of applied electric field promotes the phase transformation from anatase to rutile. Studies on photo-catalytic degradation show that the photo-catalytic activity of TiO2 thin films in an applied electric field is higher.

  1. Influence of Mo and Ta additions on solidification behavior of Ni3Al single crystal alloys

    Directory of Open Access Journals (Sweden)

    Cheng Ai

    2015-08-01

    Full Text Available Ni3Al (Ni75Al25 and Ni3Al–2Mo/Ta (Ni73.5Al24.5Mo/Ta2 single crystals were prepared by the Bridgman method under high temperature gradient (~170 °C/cm at the withdrawal rates of 5 and 20 μm/s. The experimental results showed that the addition of Mo decreased the liquidus and solidus temperatures, and the addition of Ta increased the liquidus and solidus temperatures. Meanwhile, both Mo and Ta additions were found to increase the solidification range of experimental alloy. It has been found that for solidification of stoichiometric Ni3Al at low withdrawal rate (5 μm/s, β/γ′ eutectic first solidified from liquid (L→β+γ′ and then β phase completely transformed into pure γ′ (β→γ′ after the completion of solidification. However, at high withdrawal rate of 20 μm/s, the remaining β phase was found in the as-cast microstructure of Alloy Ni3Al. Different from stoichiometric Ni3Al, the solidification sequence of Alloy Ni3Al–2Mo was identified as L→β+γ′+Mo-rich phase (ternary eutectic reaction. In addition, the addition of Ta led to the formation of primary γ′ phase and then subsequent intercellular/interdendritic β/γ′ eutectic microstructure. Based on above study, a new Ta and Mo containing Ni3Al based single crystal alloy with superior tensile strength at ultra-high temperature (>1100 °C was designed.

  2. Crystal structures of manganese and cobalt dichloride monohydrate and deuteration effects on magnetic behavior.

    Science.gov (United States)

    Pagola, S; Trowell, K T; Havas, K C; Reed, Z D; Chan, D G; Van Dongen, M J; DeFotis, G C

    2013-12-01

    This work reports the long sought crystal structures of the title members of the intriguing series of 3d transition metal dichloride monohydrates. The double chain structure which results from rearrangement of the well-known pseudo-octahedral coordination geometry and single chains in the corresponding metal chloride dihydrate is extremely unusual. MnCl2·H2O and CoCl2·H2O each crystallize in orthorhombic space group Pnma with Z = 4 and lattice parameters a = 9.0339(1), 8.8207(3); b = 3.68751(5), 3.5435(1); c = 11.5385(2), 11.2944(4) all in Å and for Mn, Co, respectively. Results are reported also for both fully deuterated systems; the structures remain the same with lattice parameter changes typically much less than 0.1%. Various magnetic properties of MnCl2·D2O and CoCl2·D2O are reported. For the latter, there are no apparent differences, qualitatively or quantitatively, from the previously measured properties of CoCl2·H2O. Interestingly, for the former some differences with respect to MnCl2·H2O are apparent, principally a lower Tmax = 3.10(10) K about which a broad antiferromagnetic maximum is centered, and a larger value χmax = 0.336(3) emu/mol. However, antiferromagnetic ordering appears to occur at essentially the same 2.18(2) K. Results of fits to susceptibilities of MnCl2·D2O and CoCl2·D2O are compared with those obtained before for MnCl2·H2O and CoCl2·H2O. Structural considerations serve to rationalize the physical properties, especially the lower dimensional magnetism of monohydrates. PMID:24251931

  3. 聚丙烯共混体系结晶行为及发泡性能研究%Study on Crystallization Behavior and Foaming Property of Polypropylene Blend System

    Institute of Scientific and Technical Information of China (English)

    陈明杰; 马卫华

    2014-01-01

    Foaming of polypropylene homo polymer(PP-H),polypropylene block copolymer(PP-B) and PP-H/PP-B blend system by using supercritical CO2 as foaming agent at a typical condition were studied. The crystallization behavior,crystal structure and morphology were characterized using differential scanning calorimetry and polarized optical microscope. The melt strength was characterized indirectly using meltflow rate tester. The morphology of the foams was observed by scanning electron microscope . The foaming behaviors of them were compared. Results show that PP-B is not only used as crystallization nucleating agent to make the spherocrystalfine and increase the density of crystallization,but also used as physical cross-link point to enhance the melt strength in the PP-H/PP-B blend system at the rate of 70∶30. The changes of the two aspects improve the foaming property of the blend system effectively,resulting in much smaller cell size,higher cell density and unbroken cells.%以均聚聚丙烯(PP-H),嵌段共聚聚丙烯(PP-B)及其共混体系为研究对象,以超临界CO2为发泡剂,选择典型工艺条件进行发泡实验,采用差示扫描量热仪和偏光显微镜研究共混前后样品的结晶行为和球晶形貌,通过熔体流动速率测试仪间接表征其熔体强度,然后采用扫描电子显微镜观察发泡样品的泡孔形态,比较其发泡行为。研究结果表明:在共混比例为70∶30的PP-H/PP-B共混体系中,由于结晶温度较高,PP-B不仅可以作为结晶成核剂,细化球晶并提高结晶密度,而且还可以作为物理交联点,提高体系的熔体强度。这两方面的改变有效地改善了共混体系的发泡性能,使其泡孔尺寸显著减小,泡孔密度有所提高并且没有明显的泡孔塌陷。

  4. Redox-active porous coordination polymer based on trinuclear pivalate: Temperature-dependent crystal rearrangement and redox-behavior

    Energy Technology Data Exchange (ETDEWEB)

    Lytvynenko, Anton S. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Kiskin, Mikhail A., E-mail: mkiskin@igic.ras.ru [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation); Dorofeeva, Victoria N.; Mishura, Andrey M.; Titov, Vladimir E.; Kolotilov, Sergey V. [L.V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, Prospekt Nauki 31, Kiev 03028 (Ukraine); Eremenko, Igor L.; Novotortsev, Vladimir M. [N.S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Prospect 31, GSP-1, 119991 Moscow (Russian Federation)

    2015-03-15

    Linking of trinuclear pivalate Fe{sub 2}NiO(Piv){sub 6} (Piv=O{sub 2}CC(CH{sub 3}){sub 3}) by 2,6-bis(4-pyridyl)-4-(1-naphthyl)pyridine (L) resulted in formation of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)·Solv, which was characterized in two forms: DMSO solvate Fe{sub 2}NiO(Piv){sub 6}(L)(DMSO)·2.5DMSO (1) or water solvate Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) (2). X-ray structure of 1 was determined. Crystal lattice of 1 at 160 K contained open channels, filled by captured solvent, while temperature growth to 296 K led to the crystal lattice rearrangement and formation of closed voids. Redox-behavior of 2 was studied by cyclic voltammetry for a solid compound, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. The presence of pores in desolvated sample Fe{sub 2}NiO(Piv){sub 6}(L) was confirmed by the measurements of N{sub 2} and H{sub 2} adsorption at 77 K. Potential barriers of the different molecules diffusion through pores were estimated by the means of molecular mechanics. - Graphical abstract: Redox-behavior of 1D-porous coordination polymer Fe{sub 2}NiO(Piv){sub 6}(L)(H{sub 2}O) was studied by cyclic voltammetry in thin film, deposited on glassy-carbon electrode. Redox-activity of L preserved upon incorporation in the coordination polymer. Potential barriers of different molecules diffusion through pores were estimated by the means of molecular mechanics. - Highlights: • Porous 1D coordination polymer was synthesized. • Temperature growth led to pores closing due to crystal lattice rearrangement. • Redox-activity of ligand preserved upon incorporation into coordination polymer. • Redox-properties of solid coordination polymer were studied in thin film. • Diffusion barriers were evaluated by molecular mechanics.

  5. Mesomorphic behavior of new benzothiazole liquid crystals having Schiff base linker and terminal methyl group

    Institute of Scientific and Technical Information of China (English)

    Sie Tiong Ha; Kok Leei Foo; Hong Cheu Lin; Masato M.Ito; Kazuma Abe; Kenji Kunbo; S.Sreehari Sastry

    2012-01-01

    A homologous series of heterocycles,6-methyl-2-(4-alkoxybenzylidenamino)benzothiazoles,were synthesized and characterized using FT-IR,1H and 13C NMR and mass spectrometric analysis.Enantiotropic nematic phase was observed for shorter members.Smectic A phase only emerged from octyloxy derivative onwards.The terminal methyl group at the benzothiazole fragment and the Schiff base linkage influenced the mesomorphic behavior of the present series.

  6. Can an Invasive Prey Species Induce Morphological and Behavioral Changes in an Endemic Predator? Evidence from a South Korean Snake (Oocatochus rufodorsatus)

    Institute of Scientific and Technical Information of China (English)

    Jun-Haeng HEO; Heon-Joo LEE; Il-Hun KIM; Jonathan J FONG; Ja-Kyeong KIM; Sumin JEONG; Daesik PARK

    2014-01-01

    Introduction of an invasive prey species into an ecosystem may affect an endemic predator’s fitness by altering the prey-predator system. Successful adaptation may allow the endemic predator to eat and control the invasive species, while unsuccessful adaptation may result in extinction of the predator. We examine the possible effects of the invasive North American bullfrog (Rana [Lithobates] catesbeiana) on the endemic Red-backed rat snake (Oocatochus rufodorsatus) in South Korea. We do so by comparing the morphology and behavior of adult and hatchling snakes from bullfrog-exposed (Taean) and bullfrog-unexposed (Hongcheon) populations. Among the seven morphological characteristics investigated, relative tail length (tail length/snout-vent length) of both adults and hatchlings from Taean was significantly greater than that of adults and hatchlings from Hongcheon. Also, adult snakes from Taean had a signiifcantly shorter latency of ifrst tongue lfick in response to prey compared to adults from Hongcheon. This difference was not observed in hatchlings. In other snake species, a longer relative tail length and shorter latency of ifrst tongue lfick are known to improve foraging efifciency, and these characters may be adaptations ofO. rufodorsatus to prey on bullfrogs. This study provides preliminary evidence that the presence of an invasive prey species may cause morphological and behavioral changes in an endemic predator.

  7. Electrochemical quartz crystal microbalance study on the two-electrode-system cyclic voltammetric behavior of Prussian blue films

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A two-channel electrochemical quartz crystal microbalance (EQCM) was used to investigate the cyclic voltammetric behavior of two Prussian blue (PB) film-modified Au electrodes in a two-electrode con-figuration in aqueous solution. The redox peaks observed in the two-electrode cyclic voltammogram (CV) are assigned to the intrinsic redox transitions among the Everitt’s salt, PB, and Prussian yellow for the film itself, the redox process of the Au substrate and the redox process of small-quantity ferri-/ferrocyanide impurities entrapped in the PB film, as also supported by ultraviolet-visible (UV-Vis) spectroelectrochemical data. The profile of the two-electrode solid-state CV for the PB powder sand-wiched between two gold-coated indium-tin oxide (ITO) electrodes is similar to that for two PB-modified Au electrodes in aqueous solution, implying similar origins for the corresponding redox peaks. The two-channel EQCM method is expected to become a highly effective technique for the studies of the two-electrode electrochemical behaviors of many other species/materials.

  8. Dispersion behavior of core-shell silica-polymer nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Core-shell silica nanoparticles are superior in modifying surface wetting behavior, enhancing nucleation and growth in crystallization, improving dispersion of naked nanoparticles, and thus upgrading the overall properties of organic polymers. The dispersion behavior and morphology of monodisperse core-shell silica particles in several polymers including polyesters are reviewed and their potential applications are discussed.

  9. The effects of initial welding temperature and welding parameters on the crystallization behaviors of laser spot welded Zr-based bulk metallic glass

    International Nuclear Information System (INIS)

    This study investigated the effects of the initial welding temperature (IWT) and welding parameters on the crystallization behaviors of laser spot welded (Zr53Cu30Ni9Al8)Si0.5 bulk metallic glass (BMG). After the welding process, the microstructure evolution, glass-forming ability (GFA) and mechanical properties of the welded samples were determined by a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and the Vicker's micro-hardness test. The results showed that the heat-affected zone (HAZ) crystallization seemed avoidable under the room temperature welding process. However, with a combination of a lower energy input (welding Condition C) and a lower IWT (at 0 deg. C), a crystallization-free HAZ was finally obtained. Using the above welding condition into the refined heat flow equation, a critical retention time of 79 ms for the crystallization temperature interval was estimated. Moreover, as the laser welded samples came to crystallization in the HAZ, it was observed that a higher content of spherical-type crystalline precipitates tended to result in a higher value of glass transition temperature, Tg. Therefore, the GFA indices, ΔTx, γ and γm, were reduced. Furthermore, it was found that the micro-hardness value in the HAZ crystallization area was decreased due to the massive cracks formed in most parts of the crystalline precipitates. For a crystallization-free HAZ, the hardness seemed unaffected.

  10. Orientation dependence of deformation and penetration behavior of tungsten single crystal rods

    International Nuclear Information System (INIS)

    This paper reports on deformation and flow at a target/penetrator interface that occurs under conditions of high hydrostatic pressure and associated heat generation. To further elucidate the role of material structure in the penetration process, oriented single crystals of tungsten have been launched into steel targets and the residual penetrators recovered and analyzed. Both the penetration depth and the deformation characteristics were strongly influenced by the crystallographic orientation. Deformation modes for the left-angle 100 right-angle rod, which exhibited the best performance, appeared to involve considerable localized slip/cleavage and relatively less plastic working; the residual penetrator was extensively cracked and the eroded penetrator material was extruded in a smooth tube lined with an oriented array of discrete particle exhibiting cleavage fractures. Deformation appeared to be much less localized and to involve more extensive plastic working in the left-angle 011 right-angle rod, which exhibited the poorest penetration, while the left-angle 111 right-angle behaved in an intermediate fashion

  11. Influence of Processing Parameters on the Solidification Behavior of Single-Crystal CMSX-4 Superalloy

    Science.gov (United States)

    Wang, Fu; Ma, Dexin; Bogner, Samuel; Bührig-Polaczek, Andreas

    2016-07-01

    The microstructural evolution of a superalloy, single-crystal CMSX-4 solidified at different withdrawal rates was investigated using a directional solidification quenching method. Analyses of the cross-sections within mushy zones generated the evolution of the solid volume fractions ( f s) during the reduction in the temperature and the solidification sequences. At the withdrawal rate of 0.3 mm min-1, f s increases by about 81 pct within the first 23 pct of the solidification interval, whereas it increases by about 64 pct at the withdrawal rate of 0.7 mm min-1. The Bower-Brody-Flemings model can characterize the evolution tendency of f s curve at the lower withdrawal rate, while it can not only describe the changing tendency of f s, but also precisely predict the f s values at higher withdrawal rate. With increasing withdrawal rate, the solidification intervals of the γ dendrite and γ/ γ' eutectics are increased. In addition to this, the forming site of the γ/ γ' eutectic at the lower withdrawal rate lags behind that at the higher withdrawal rate. At both the withdrawal rates the solidification of the γ/ γ' eutectic islands commences with the γ/ γ' core formed on the surface of the γ dendrites, then progressed spatially and developed the coarse γ/ γ' structure.

  12. Fundamentals of poly(lactic acid) microstructure, crystallization behavior, and properties

    Science.gov (United States)

    Kang, Shuhui

    Poly(lactic acid) is an environmentally-benign biodegradable and sustainable thermoplastic material, which has found broad applications as food packaging films and as non-woven fibers. The crystallization and deformation mechanisms of the polymer are largely determined by the distribution of conformation and configuration. Knowledge of these mechanisms is needed to understand the mechanical and thermal properties on which processing conditions mainly depend. In conjunction with laser light scattering, Raman spectroscopy and normal coordinate analysis are used in this thesis to elucidate these properties. Vibrational spectroscopic theory, Flory's rotational isomeric state (RIS) theory, Gaussian chain statistics and statistical mechanics are used to relate experimental data to molecular chain structure. A refined RIS model is proposed, chain rigidity recalculated and chain statistics discussed. A Raman spectroscopic characterization method for crystalline and amorphous phase orientation has been developed. A shrinkage model is also proposed to interpret the dimensional stability for fibers and uni- or biaxially stretched films. A study of stereocomplexation formed by poly(l-lactic acid) and poly(d-lactic acid) is also presented.

  13. Study of Crystal Defect Behaviors in CeO2-Based Electrolyte

    Institute of Scientific and Technical Information of China (English)

    Ma Zhifang; Liang Guangchuan; Liang Jinsheng

    2004-01-01

    The defect behaviors, such as fundamental point defect, defect pair formation and oxygen vacancy migration in ceria, were studied on the basis of energy minimization calculations. The result shows that anion Frenkel disorder is the preferred intrinsic disorder, and it is easier to be dissolved in CeO2 for CaO and SrO than for MgO and BaO via an oxygen vacancy compensation mechanism. The association energy of an oxygen vacancy with a substitutional cation depends on dopant cation radius. The favorable migration route for oxygen vacancy with the lowest migration energy is from the second neighbor site to another one.

  14. Beyond R2D2: the design of nonverbal interaction behavior optimized for robotic-specific morphologies

    NARCIS (Netherlands)

    Karreman, Daphne Eleonora

    2016-01-01

    It is likely that in the near future we will meet more and more robots that will perform tasks in social environments, such a museum or tourist site. However, design guidelines that inform the design of effective nonverbal behavior for robots are scarce. This is surprising since the behavior of robo

  15. Poly(butylene terephthalate)/montmorillonite nanocomposites: Effect of montmorillonite on the morphology, crystalline structure, isothermal crystallization kinetics and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Kalkar, Arun K., E-mail: drarunkalkar@gmail.com; Deshpande, Vineeta D.; Vatsaraj, Bhakti S.

    2013-09-20

    Graphical abstract: - Highlights: • Effect of amount of clay content, its dispersion on crystalline structure of PBT. • Regime break temperature shifts to lower temperature for PCN4 up to 197 °C. • Tensile modulus enhanced up to 95% for PCN3 compared to PBT. - Abstract: Nanocomposites (PCNs), based on poly(butylene terephthalte) (PBT) and organoclay (Cloisite-15A) MMT were prepared by melt intercalation compounding process. The nanoscale dispersion and the microcrystal structure studied qualitatively using; X-ray diffraction (XRD) and electron microscopy (SEM, TEM and AFM). The XRD results indicated that the crystal size is highly dependent on the crystallization temperature. The isothermal crystallization kinetics of PBT in PCNs analysis indicated that the overall crystallization of PBT involved heterogeneous nucleated three-dimensional spherical primary crystallization growth process. The crystallization rate, however, is dependent on the PCN-composition, crystallization temperature and the dispersion state of clay in PCNs. Further analysis, based on Hoffman-Lauritzen theory revealed that the neat PBT and PBT in PCNs crystallization follow regime-II kinetics for temperature 195 °C–205 °C and enters the regime-III kinetics in lower T{sub c} range, 185 °C–195 °C. The improvement in mechanical properties is highly dependent on the level of clay exfoliation in PBT matrix.

  16. On the crystallization behavior of syndiotactic-b-atactic polystyrene stereodiblock copolymers, atactic/syndiotactic polystyrene blends, and aPS/sPS blends modified with sPS-b-aPS

    Energy Technology Data Exchange (ETDEWEB)

    Annunziata, Liana, E-mail: liana.annunziatta@univ-rennes1.fr [Organométalliques et Catalyse, UMR 6226 Sciences Chimiques CNRS, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex (France); Monasse, Bernard, E-mail: bernard.monasse@mines-paristech.fr [Mines-ParisTech, CEMEF, Centre de Mise en Forme des Matériaux, UMR CNRS 7635, Sophia Antipolis (France); Rizzo, Paola; Guerra, Gaetano [Dipartimento di Chimica e Biologia, Università degli studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano, SA (Italy); Duc, Michel [Total Petrochemicals Research Feluy, Zone Industrielle Feluy C, B-7181 Seneffe (Belgium); Carpentier, Jean-François, E-mail: jean-francois.carpentier@univ-rennes1.fr [Organométalliques et Catalyse, UMR 6226 Sciences Chimiques CNRS, Université de Rennes 1, Campus de Beaulieu, F-35042 Rennes Cedex (France)

    2013-09-16

    Crystallization and morphological features of syndiotactic-b-atactic polystyrene stereodiblock copolymers (sPS-b-aPS), atactic/syndiotactic polystyrene blends (aPS/sPS), and aPS/sPS blends modified with sPS-b-aPS, with different compositions in aPS and sPS, have been investigated using differential scanning calorimetry (DSC), polarized light optical microscopy (POM) and wide angle X-ray diffraction (WAXRD) techniques. For comparative purposes, the properties of parent pristine sPS samples were also studied. WAXRD analyses revealed for all the samples, independently from their composition (aPS/sPS ratio) and structure (blends, block copolymers, blends modified with block copolymers), the same polymorphic β form of sPS. The molecular weight of aPS and sPS showed opposite effects on the crystallization of 50:50 aPS/sPS blends: the lower the molecular weight of aPS, the slower the crystallization while the lower the molecular weight of sPS, the faster the crystallization. DSC studies performed under both isothermal and non-isothermal conditions, independently confirmed by POM studies, led to a clear trend for the crystallization rate at a given sPS/aPS ratio (ca. 50:50 and 20:80): sPS homopolymers > sPS-b-aPS block copolymers ∼sPS/aPS blends modified with sPS-b-aPS copolymers > sPS/aPS blends. Interestingly, sPS-b-aPS block copolymers not only crystallized faster than blends, but also affected positively the crystallization behavior of blends. At 50:50 sPS/aPS ratio, blends (Blend-2), block copolymers (Cop-1) and blends modified with block copolymers (Blend-2-mod) crystallized via spherulitic crystalline growth controlled by an interfacial process. In all cases, an instantaneous nucleation was observed. The density of nuclei in block copolymers (160,000−190,000 nuclei mm{sup −3}) was always higher than that in blends and modified blends (30,000−60,000 nuclei mm{sup −3}), even for quite different sPS/aPS ratio. At 20:80 sPS/aPS ratio, the block copolymers

  17. Behavior of H(sub2)O and OH in lawsonite : a single crystal neutron diffraction and Raman spectroscopic investigation.

    Energy Technology Data Exchange (ETDEWEB)

    Kolesov, B. A.; Lager, G. A.; Schultz, A. J.; Russian Academy of Science; Univ. of Louisville

    2008-01-01

    Neutron diffraction and polarized single-crystal Raman spectroscopic measurements were made on the high-pressure silicate lawsonite, CaAl{sub 2}(Si{sub 2}O{sub 7})(OH){sub 2} {center_dot} H{sub 2}O, from Tiburon Peninsula, California. For the diffraction measurements, intensity reflection data were collected at temperatures of 295, 110 and 20 K using time-of-flight neutron diffraction methods to further examine two reversible, order-disorder type phase transitions occurring at 273 and 155 K [Cmcm (> 273 K) {yields} Pmcn (< 273 K) {yields} P2{sub 1}cn (< 155 K)]. These data are also used to model the H atom displacements in lawsonite as a function of temperature and to provide better insight into the nature of H bonding. The Raman spectroscopic measurements (2500 to 4000 cm{sup -1} at 4 {ge} T {ge} 300 K) were carried out on the same crystal used for the neutron diffraction study. Four OH-related bands are observed between 2700 and 3600 cm{sup -1}. The OH groups and H{sub 2}O molecules, which are linked by hydrogen bonding, build quasi one-dimensional chains in lawsonite, that run parallel to [001] and thus a model consisting of isolated oscillators cannot be used to interpret the spectra at ambient temperature. A notable feature of spectral behavior at 240-260 K in the vicinity of the Cmcm {leftrightarrow} Pmcn phase transition is the change-over of strong hydrogen bonding from the OH group to the H{sub 2}O molecule. The lowest-wavenumber OH(H{sub 2}O) band at 2780 cm{sup -1} at 4 K is broad and asymmetric, which is related to strong hydrogen bonding, and is characterized by strong anharmonicity. This band was deconvoluted into a number of combination modes consisting of an internal-H{sub 2}O and various external-H{sub 2}O vibrations.

  18. Goethite surface reactivity: III. Unifying arsenate adsorption behavior through a variable crystal face - Site density model

    Science.gov (United States)

    Salazar-Camacho, Carlos; Villalobos, Mario

    2010-04-01

    We developed a model that describes quantitatively the arsenate adsorption behavior for any goethite preparation as a function of pH and ionic strength, by using one basic surface arsenate stoichiometry, with two affinity constants. The model combines a face distribution-crystallographic site density model for goethite with tenets of the Triple Layer and CD-MUSIC surface complexation models, and is self-consistent with its adsorption behavior towards protons, electrolytes, and other ions investigated previously. Five different systems of published arsenate adsorption data were used to calibrate the model spanning a wide range of chemical conditions, which included adsorption isotherms at different pH values, and adsorption pH-edges at different As(V) loadings, both at different ionic strengths and background electrolytes. Four additional goethite-arsenate systems reported with limited characterization and adsorption data were accurately described by the model developed. The adsorption reaction proposed is: lbond2 FeOH +lbond2 SOH +AsO43-+H→lbond2 FeOAsO3[2-]…SOH+HO where lbond2 SOH is an adjacent surface site to lbond2 FeOH; with log K = 21.6 ± 0.7 when lbond2 SOH is another lbond2 FeOH, and log K = 18.75 ± 0.9, when lbond2 SOH is lbond2 Fe 2OH. An additional small contribution of a protonated complex was required to describe data at low pH and very high arsenate loadings. The model considered goethites above 80 m 2/g as ideally composed of 70% face (1 0 1) and 30% face (0 0 1), resulting in a site density for lbond2 FeOH and for lbond2 Fe 3OH of 3.125/nm 2 each. Below 80 m 2/g surface capacity increases progressively with decreasing area, which was modeled by considering a progressively increasing proportion of faces (0 1 0)/(1 0 1), because face (0 1 0) shows a much higher site density of lbond2 FeOH groups. Computation of the specific proportion of faces, and thus of the site densities for the three types of crystallographic surface groups present in

  19. Magnetoelectronic phase separation in La1-xSrxCoO3 single crystals: Evidence from critical behavior

    Science.gov (United States)

    Khan, N.; Mandal, P.; Mydeen, K.; Prabhakaran, D.

    2012-06-01

    We have investigated the critical behavior of ferromagnetic La0.75Sr0.25CoO3 and La0.79Sr0.21CoO3 single crystals from the bulk magnetization measurements around their Curie temperature (TC). The detailed analysis of the dc magnetization data using different techniques such as the Kouvel-Fisher, the Arrott-Noaks, and critical isotherm plots yield the critical exponents of β=0.362±0.002, γ=1.304±0.006, and δ=4.75±0.01 with TC=213.93±0.02 K for La0.75Sr0.25CoO3 and β=0.491±0.004, γ=1.217±0.003, and δ=3.51±0.01 with TC=187.67±0.01 K for La0.79Sr0.21CoO3, characterizing these second-order phase transitions. For both the crystals, the scaling of the magnetization data above and below TC obtained using the respective critical exponents and the consistency in the values of the critical exponents determined by different methods confirm that the calculated exponents are unambiguous and intrinsic. The obtained values of exponents suggest that for La0.75Sr0.25CoO3 the transition falls into the three-dimensional Heisenberg universality class of the near-neighbor interaction as proposed for double-exchange systems, whereas in the case of La0.79Sr0.21CoO3 the transition is characterized by mean-field-like values of the critical exponents. We have also estimated the reduced critical amplitudes and observed that for La0.75Sr0.25CoO3 they fall well within the range of the Heisenberg model prediction for spin S>1/2, whereas for La0.79Sr0.21CoO3 they are found to be shifted toward the mean-field values. The deviation of the critical exponents from 3D Heisenberg values toward mean-field ones is attributed to the presence of magnetoelectronic phase inhomogeneity in the x=0.21 single crystal. The detailed analysis of the specific-heat data in the vicinity of TC for the x=0.33, 0.25, and 0.21 samples also supports the phase separation scenario at around x=0.21.

  20. Analysis of the effect of gallium content on the magnetomechanical behavior of single-crystal FeGa alloys using an energy-based model

    International Nuclear Information System (INIS)

    The magnetomechanical behavior of single-crystal iron–gallium alloys with varying gallium content was found to be strongly dependent on the Ga content (Atulasimha 2006 PhD Thesis). An energy-based model (Atulasimha 2006 PhD Thesis, Armstrong and William 1997 J. Appl. Phys. 81 2321) is employed to simulate the strikingly different actuation behavior (λ–H and B–H curves under different compressive stresses) and validated against experimental data for 19, 24.7 and 29 at.% Ga, [100] oriented, slow-cooled single-crystal FeGa alloys. The effect of gallium content on the model parameters, specifically the cubic magnetocrystalline anisotropy constants and the Armstrong-smoothing factor Ω, their physical significance and ultimately their effect on the magnetomechanical behavior are analyzed and explained

  1. Growth and characterization of DAST crystal with large-thickness

    Science.gov (United States)

    Cao, Lifeng; Teng, Bing; Zhong, Degao; Hao, Lun; Sun, Qing

    2016-10-01

    Highly nonlinear optical 4-N, N-dimethylamino-4-N-methyl stilbazolium tosylate (DAST) crystals with large surface and thickness was grown by the slope nucleation technology with slow-cooling in a high concentration solution. The structure and composition of the crystal were confirmed by X-ray diffraction (XRD). The surface morphology of the crystal was characterized by optical microscope. Growth layers were observed on the (001) surface and several isolated "island layers" were also found. The mechanism of crystal growth was analyzed. Etching behavior of the (001) and (00 1 bar) faces of the crystal was studied with methanol, respectively. Optical properties of the crystal were also characterized by UV-vis-NIR spectrometer. The dielectric constants and the dielectric loss were tested by impedance analyzer.

  2. MORPHOLOGY EVOLUTION IN PTFE AS A FUNCTION OF MELT TIME AND TEMPERATURE Ⅰ. HIGH MOLECULAR WEIGHT SINGLE- AND MULTI-MOLECULE FOLDED CHAIN SINGLE CRYSTALS AND BAND STRUCTURES

    Institute of Scientific and Technical Information of China (English)

    J.Yang; K.L.Petersen; R.A.Williams; P.H.Geil; T.C.Long; P.Xu

    2005-01-01

    The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weight polytetrafluoroethylene (PTFE) on a substrate as a function of "melt" time and temperature is described. Folded chain single crystals parallel to the substrate and as ribbons on-edge (with double striations), as well as bands, are produced for longer sintering times; particle merger and diffusion of individual molecules, crystallizing as folded chain, single (or few) molecule,single crystals when "trapped" on the substrate by cooling occur for shorter sintering times. It is suggested the observed structures develop with sintering time, in a mesomorphic melt. The structure of the nascent particles is also discussed.

  3. Crystallization phenomena of isotactic polystyrene

    NARCIS (Netherlands)

    Lemstra, Peter Jan

    1975-01-01

    In this thesis the crystallization behavior of isotactic polystyrene has been described. The kinetics of the crystallization process and the crystalline structure were studied both for crystallization in the bulk and from dilute solutions. ... Zie Summary

  4. Meek males and fighting females: sexually-dimorphic antipredator behavior and locomotor performance is explained by morphology in bark scorpions (Centruroides vittatus.

    Directory of Open Access Journals (Sweden)

    Bradley E Carlson

    Full Text Available Sexual dimorphism can result from sexual or ecological selective pressures, but the importance of alternative reproductive roles and trait compensation in generating phenotypic differences between the sexes is poorly understood. We evaluated morphological and behavioral sexual dimorphism in striped bark scorpions (Centruroides vittatus. We propose that reproductive roles have driven sexually dimorphic body mass in this species which produces sex differences in locomotor performance. Poor locomotor performance in the females (due to the burden of being gravid favors compensatory aggression as part of an alternative defensive strategy, while male morphology is coadapted to support a sprinting-based defensive strategy. We tested the effects of sex and morphology on stinging and sprinting performance and characterized overall differences between the sexes in aggressiveness towards simulated threats. Greater body mass was associated with higher sting rates and slower sprinting within sexes, which explained the greater aggression of females (the heavier sex and, along with longer legs in males, the improved sprint performance in males. These findings suggest females are aggressive to compensate for locomotor costs of reproduction while males possess longer legs to enhance sprinting for predator evasion and mate finding. Sexual dimorphism in the metasoma ("tail" was unrelated to stinging and sprinting performance and may best be explained by sexual selection.

  5. Meek males and fighting females: sexually-dimorphic antipredator behavior and locomotor performance is explained by morphology in bark scorpions (Centruroides vittatus).

    Science.gov (United States)

    Carlson, Bradley E; McGinley, Shannen; Rowe, Matthew P

    2014-01-01

    Sexual dimorphism can result from sexual or ecological selective pressures, but the importance of alternative reproductive roles and trait compensation in generating phenotypic differences between the sexes is poorly understood. We evaluated morphological and behavioral sexual dimorphism in striped bark scorpions (Centruroides vittatus). We propose that reproductive roles have driven sexually dimorphic body mass in this species which produces sex differences in locomotor performance. Poor locomotor performance in the females (due to the burden of being gravid) favors compensatory aggression as part of an alternative defensive strategy, while male morphology is coadapted to support a sprinting-based defensive strategy. We tested the effects of sex and morphology on stinging and sprinting performance and characterized overall differences between the sexes in aggressiveness towards simulated threats. Greater body mass was associated with higher sting rates and slower sprinting within sexes, which explained the greater aggression of females (the heavier sex) and, along with longer legs in males, the improved sprint performance in males. These findings suggest females are aggressive to compensate for locomotor costs of reproduction while males possess longer legs to enhance sprinting for predator evasion and mate finding. Sexual dimorphism in the metasoma ("tail") was unrelated to stinging and sprinting performance and may best be explained by sexual selection. PMID:24870611

  6. Crystalline structures and crystallization behaviors of poly(L-lactide) in poly(L-lactide)/graphene nanosheet composites

    DEFF Research Database (Denmark)

    Li, Jingqing; Xiao, Peitao; Li, Hongfei;

    2015-01-01

    to be more preferred than α form PLLA formation in PLLA/GNS composites at crystallization temperatures Tcs within the α′–α crystal formation transition region due to the existence of GNSs, resulting in an obvious shift of the α′–α crystal formation transition of PLLA in PLLA/GNSs towards high Tcs compared...... with that of pure PLLA. At Tcs below α′–α crystal formation transition, the formed α′ crystal turned to be more imperfect due to GNS addition, while at Tcs above α′–α crystal formation transition, the crystal structure of α form PLLA was not affected by GNSs. Further POM observations at high Tcs with only α crystal...... formed showed that PLLA spherulites were well formed in both PLLA/GNSs and pure PLLA, however with very different crystallization kinetics while isothermally crystallizing at different Tcs. The PLLA crystallization process of PLLA in PLLA/GNSs was accelerated by GNSs with both the nucleation rate...

  7. Growth and characterization of organic single crystal benzyl carbamate

    Science.gov (United States)

    Bala Solanki, S. Siva; Perumal, Rajesh Narayana; Suthan, T.; Bhagavannarayana, G.

    2015-10-01

    Benzyl carbamate single crystal is grown by a solution and vertical Bridgman technique for the first time. The cell parameters and morphologies are assessed from single crystal X-ray diffraction analysis. High resolution X-ray diffraction analysis indicates the crystalline perfection of the grown benzyl carbamate crystal. Fourier Transforms Infrared spectroscopy study has been applied to arrive at the different functional groups. Thermo gravimetric analysis and differential scanning calorimetry are used to study its thermal behavior. The microhardness test is carried out and the load dependent hardness is measured.

  8. Crystallization behavior in Se{sub 90}Te{sub 10} and Se{sub 80}Te{sub 20} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Barták, Jaroslav, E-mail: j-bartak@seznam.cz; Málek, Jirí [Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice (Czech Republic); Koštál, Petr [Department of Inorganic Technology, Faculty of Chemical Technology, University of Pardubice, Doubravice 41, 532 10 Pardubice (Czech Republic); Segawa, Hiroyo; Yamabe-Mitarai, Yoko [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-03-28

    Isothermal crystal growth kinetics in Se{sub 90}Te{sub 10} and Se{sub 80}Te{sub 20} thin films was studied by microscopy and in situ X-ray diffraction (XRD) measurements. The spherulite-like crystals grew linearly with time. In a narrow temperature range of between 65 and 85 °C, crystal growth rates exhibit simple exponential behavior with activation energies E{sub G} = 193 ± 4 kJ mol{sup −1} for Se{sub 90}Te{sub 10} and E{sub G} = 195 ± 4 kJ mol{sup −1} for Se{sub 80}Te{sub 20}. The crystal growth in both compositions is controlled by liquid-crystal interface kinetics and can be described by a screw dislocation growth model. From the XRD data, the crystallization fraction was estimated. The crystallization data were described by Johnson-Mehl-Avrami (JMA) model with Avrami exponents m = 1.4 ± 0.3 for Se{sub 90}Te{sub 10} and m = 1.6 ± 0.4 for Se{sub 80}Te{sub 20}. Activation energies were estimated from the temperature dependence of rate constant evaluated from the JMA model. The activation energies of nucleation-growth process were found to be E{sub c} = 184 ± 21 kJ mol{sup −1} for Se{sub 90}Te{sub 10} and E{sub c} = 179 ± 7 kJ mol{sup −1} for Se{sub 80}Te{sub 20}, and are comparable with activation energies of crystal growth.

  9. Long-time behavior for a nematic liquid crystal model with asymptotic stabilizing boundary condition and external force

    CERN Document Server

    Grasselli, Maurizio

    2011-01-01

    We consider an approximation of the well-known Ericksen-Leslie model for the nematic liquid crystal flow proposed by F.-H. Lin et al. The evolution system consists of the Navier-Stokes equations coupled with a convective Ginzburg-Landau type equation for the (vector-valued) averaged molecular orientations. Here we suppose that the latter is subject to a time-dependent Dirichlet boundary condition h(t), while the Navier--Stokes equations are characterized by a no-slip boundary condition and by a time-dependent external force g(t). We show that, in 2D, each global weak solution converges to a single stationary state when h(t) and g(t) suitably converge to a time-independent boundary datum h_\\infty and 0, respectively. We also provide some estimates of the convergence rate. In the 3D case, we prove a similar long-time behavior for global strong solutions, provided that either the viscosity is large enough or the initial datum is close to a given equilibrium.

  10. Analytical solutions and numerical tests of elastic and failure behaviors of close-packed lattice for brittle rocks and crystals

    Science.gov (United States)

    Liu, Chu; Pollard, David D.; Shi, Bin

    2013-01-01

    Analytical solutions of elastic properties and failure modes of a two-dimensional close-packed discrete element model are proposed. Based on the assumption of small deformation, the conversion formulas between five inter-particle parameters of the lattice model and rock mechanical properties were derived. Using the formulas, the inter-particle parameters can be determined by Young's modulus (E), Poisson's ratio (v), tensile strength (Tu), compressive strength (Cu), and coefficient of intrinsic friction (μi). The lattice defined by the parameters simulates the elastic and failure behaviors of rocks and crystals and therefore can be used to investigate the initiation and development of geological structures quantitatively. Furthermore, the solutions also provide a theoretical basis for the calibration of parameters of random discrete assemblies. The model of quartz was used as an example to validate the formulas and test the errors. The simulated results show that E and v converge to theoretical values when particle number increases. These elastic properties are almost constant when the magnitude of strain is lower than 10-3. The simulated Tu and Cu of a single three-element unit are also consistent with the formulas. However, due to the boundary effects and stress concentrations, Tu and Cu of lattices with multiple units are lower than the values predicted by the formulas. Therefore, greater Tu and Cu can be used in the formulas to counteract this effect. The model is applicable to the simulation of complicated structures that involve deformation and failure at different scales.

  11. Discovery of room-temperature spin-glass behaviors in two-dimensional oriented attached single crystals

    Science.gov (United States)

    Ma, Ji; Chen, Kezheng

    2016-05-01

    In this study, room-temperature spin-glass behaviors were observed in flake-like oriented attached hematite (α-Fe2O3) and iron phosphate hydroxide hydrate (Fe5(PO4)4(OH)3·2H2O) single crystals. Remarkably, their coercivity (HC) values were found to be almost invariable at various given temperatures from 5 to 300 K. The spin topographic map in these flakes was assumed as superparamagnetic (SPM) "islands" isolated by spin glass (SG)-like "bridges". A spin-glass model was then proposed to demonstrate the spin frustration within these "bridges", which were formed by the staggered atomic planes in the uneven surfaces belonging to different attached nanoparticles. Under the spatial limitation and coupling shield of these "bridges", the SPM "islands" were found to be collectively frozen to form a superspin glass (SSG) state below 80 K in weak applied magnetic fields; whereas, when strong magnetic fields were applied, the magnetic coupling of these "islands" would become superferromagnetic (SFM) through tunneling superexchange, so that, these SFM spins could antiferromagnetically couple with the SG-like "bridges" to yield pronounced exchange bias (EB) effect.

  12. Adolescent exposure to cocaine increases anxiety-like behavior and induces morphologic and neurochemical changes in the hippocampus of adult rats.

    Science.gov (United States)

    Zhu, W; Mao, Z; Zhu, C; Li, M; Cao, C; Guan, Y; Yuan, J; Xie, G; Guan, X

    2016-01-28

    Repeated exposure to cocaine during adolescence may affect both physical and psychological conditions in the brain, and increase the risk of psychiatric disorders and addiction behaviors in adulthood. Adolescence represents a critical development period for the hippocampus. Moreover, different regions of the hippocampus are involved in different functions. Dorsal hippocampus (dHP) has been implicated in learning and memory, whereas ventral hippocampus (vHP) plays an important role in emotional processing. In this study, the rats that were exposed to cocaine during adolescence (postnatal days, P28-P42) showed higher anxiety-like behavior in the elevated plus maze test in adulthood (P80), but displayed normal spatial learning and memory in the Morris water maze test. Furthermore, repeated exposure to cocaine during adolescence lead to alterations in morphology of pyramidal neurons, activities of astrocytes, and levels of proteins that involved in synaptic transmission, apoptosis, inflammation and addiction in both dHP and vHP of adult rats. These findings suggest that repeated exposure to cocaine during adolescence in rats may elicit morphologic and neurochemical changes in the hippocampus when the animals reach adulthood. These changes may contribute to the increased susceptibility for psychiatric disorders and addiction seen in adults. PMID:26621120

  13. Effect of the precise branching of polyethylene at each 21st CH2 group on its phase transitions, crystal structure, and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Qui, Wulin [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Sworen, John [University of Florida, Jackson Laboratory; Pyda, Marek {nmn} [ORNL; Nowak-Pyda, Elisabieta [University of Tennessee, Knoxville (UTK); Habenschuss, Anton {Tony} [ORNL; Wagener, Kenneth [University of Florida; Wunderlich, Bernhard {nmn} [ORNL

    2006-01-01

    Three linear polyethylenes with branches at every 21st backbone atom have been analyzed by differential scanning calorimetry (DSC) and quasi-isothermal, temperature-modulated DSC. The branches were methyl (PE1M), dimethyl (PE2M), and ethyl groups (PE1E). Linear polyethylene (HDPE) and atactic poly(octadecyl acrylate) (PODA) were also analyzed. All were compared to a random poly(ethylene-co-octene-1) of similar branch concentration (LLDPE) and poly(4,4'-phthaloimidobenzoyldoeicosyleneoxycarbonyl) (PEIM-22). The HDPE has the highest melting temperature and crystallinity with relatively large contributions of reversing melting when grown as folded-chain crystals. The precisely branched polyethylenes and copolymers have lower melting temperatures and heats of fusion. Of the branched samples, PE1M crystallizes more readily, followed by PE1E and PE2M, with PE2M showing cold crystallization. In contrast to paraffins of equal length which melt fully reversibly, the precisely designed, branched polymers melt largely irreversibly with small amounts of reversing melting, which is least for the best-grown crystals. The PE1M forms monoclinic, PE1E, pseudohexagonal, or triclinic crystals, and PE2M has a multitude of crystal structures.

  14. Influence of La2O3 on crystallization behavior of free-fluoride mould flux and heat transfer of slag films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fang; CHEN Yuan; WANG Yici; DONG Fang; WU Meiqiang

    2011-01-01

    In order to research the influence of La2O3 on crystallization behavior of free-fluoride mould flux and the heat transfer of slag film,flee-fluoride mould flux with various La2O3 content were investigated by using self-made mould simulator, comprehensive thermal analyzer and SEM-EDS. With the increase of La2O3 content from 0% to 20%, the crystallization ratios of mould flux films were improved from 2% to 90% and the thicknesses of films were also enhanced over two times. Moreover, crystallization temperature was greatly raised and its increasing extent reached 100 ℃. It could also decrease the melting temperature of casting powder about 50 ℃. However, the undissolved La2O3 particles appeared in slag film if the ratio of La2O3 in flee-fluoride mould flux was much too high.

  15. Morphology and In Vitro Behavior of Electrospun Fibrous Poly(D,L-lactic acid for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Toshihiro Inami

    2013-01-01

    Full Text Available This work describes the fabrication, optimization, and characterization of electrospun fibrous poly(D,L-lactic acid (PDLLA for biomedical applications. The influences of the polymer concentration of the electrospinning solution (5, 10, or 15 wt% and the solution flow rate (0.1, 0.5, 1.0, or 2.0 mL/h on the morphology of the obtained fibrous PDLLA were evaluated. The in vitro biocompatibility of two types of PDLLA, ester terminated PDLLA (PDLLA-R and carboxyl terminated PDLLA (PDLLA-COOH, was evaluated by monitoring apatite formation on samples immersed in Hanks’ balanced salt (HBS solution. 15 wt% polymer solution was the most beneficial for preparing a fibrous PDLLA structure. Meanwhile, no differences in morphology were observed for PDLLA prepared at various flow rates. Apatite precipitate is formed on both types of PDLLA only 1 day after immersion in HBS solution. After 7 days of immersion, PDLLA-COOH showed greater apatite formation ability compared with that of PDLLA-R, as measured by thin-film X-ray diffraction. The results indicated that the carboxyl group is effective for apatite precipitation in the body environment.

  16. CRYSTALLIZATION OF BLENDS OF AN ASYMMETRIC POLY(OXYETHYLENE)-b-POLY(OXYBUTYLENE) BLOCK COPOLYMER WITH POLY(OXYBUTYLENE)

    Institute of Scientific and Technical Information of China (English)

    Jun-ting Xu; Guo-dong Liang; Shao-min Mai; A. J. Ryan

    2004-01-01

    An oxyethylene/oxybutylene block copolymer with asymmetric volume fraction (E115B103) was blended with oxybutylene homopolymer (Bh) at different volume fractions of the block (φE). Crystallization behavior of the blends was studied and was compared with that of the blends from a symmetric block copolymer (E114B56). It was found that the crystallization temperature of E115B103/B28 blend is lower than that of the blends from symmetric block copolymer. For the blend with φE= 0.30 breakout crystallization with an Avrami exponent n ≈ 3.0 is observed. At φE = 0.22 the blend exhibits a variable crystallization behavior: confined crystallization with n ≈ 1.0 at lower crystallization temperatures but breakout crystallization at high crystallization temperatures. For the blend with φE = 0.14 and sphere morphology confined crystallization occurs at all crystallization temperatures studied. When compared with the blends from symmetric block copolymer, confined crystallization occurs more easily in the E115B103/B28 blends. The SAXS results agree with the isothermal crystallization kinetics. Deformation of the confined crystalline block is observed in the blend with φE = 0.14 and mixed lamellar and cylinder morphologies in the blend with φE = 0.22.

  17. Transport Processes in Dendritic Crystallization

    Science.gov (United States)

    Glicksman, M. E.

    1984-01-01

    Free dentritic growth refers to the unconstrained development of crystals within a supercooled melt, which is the classical dendrite problem. The development of theoretical understanding of dendritic growth and its experimental status is sketched showing that transport theory and interfacial thermodynamics (capillarity theory) are insufficient ingredients to develop a truly predictive model of dendrite formation. The convenient, but incorrect, notion of maximum velocity was used for many years to estimate the behavior of dendritic transformations until supplanted by modern dynamic stability theory. The proper combinations of transport theory and morphological stability seem to be able to predict the salient aspects of dendritic growth, especially in the neighborhood of the tip.

  18. Reduced Anxiety-Like Behavior and Altered Hippocampal Morphology in Female p75NTRexon IV−/− Mice

    Science.gov (United States)

    Puschban, Zoe; Sah, Anupam; Grutsch, Isabella; Singewald, Nicolas; Dechant, Georg

    2016-01-01

    The presence of the p75 neurotrophin receptor (p75NTR) in adult basal forebrain cholinergic neurons, precursor cells in the subventricular cell layer and the subgranular cell layer of the hippocampus has been linked to alterations in learning as well as anxiety- and depression- related behaviors. In contrast to previous studies performed in a p75NTRexon III−/− model still expressing the short isoform of the p75NTR, we focused on locomotor and anxiety–associated behavior in p75NTRexon IV−/− mice lacking both p75NTR isoforms. Comparing p75NTRexon IV−/− and wildtype mice for both male and female animals showed an anxiolytic-like behavior as evidenced by increased central activities in the open field paradigm and flex field activity system as well as higher numbers of open arm entries in the elevated plus maze test in female p75NTR knockout mice. Morphometrical analyses of dorsal and ventral hippocampus revealed a reduction of width of the dentate gyrus and the granular cell layer in the dorsal but not ventral hippocampus in male and female p75NTRexon IV−/− mice. We conclude that germ-line deletion of p75NTR seems to differentially affect morphometry of dorsal and ventral dentate gyrus and that p75NTR may play a role in anxiety-like behavior, specifically in female mice. PMID:27313517

  19. Reduced anxiety-like behavior and altered hippocampal morphology in female p75NTR exon IV-/- mice.

    Directory of Open Access Journals (Sweden)

    Zoe ePuschban

    2016-06-01

    Full Text Available The presence of the neurotrophin receptor p75NTR in adult basal forebrain cholinergic neurons, precursor cells in the subventricular cell layer and the subgranular cell layer of the hippocampus has been linked to alterations in learning as well as anxiety- and depression- related behaviors. In contrast to previous studies performed in a p75NTR exonIII-/- model still expressing the short isoform of the p75NTR, we focused on locomotor and anxiety–associated behavior in p75NTR exonIV-/- mice lacking both p75NTR isoforms. Comparing p75NTR exonIV-/- and wildtype mice for both male and female animals showed an anxiolytic-like behavior as evidenced by increased central activities in the open field paradigm and flex field activity system as well as higher numbers of open arm entries in the elevated plus maze test in female p75NTR knockout mice.Morphometrical analyses of dorsal and ventral hippocampus revealed a reduction of width of the dentate gyrus and the granular cell layer in the dorsal but not ventral hippocampus in male and female p75NTR exonIV -/- mice. We conclude that germ-line deletion of p75NTR seems to differentially affect morphometry of dorsal and ventral dentate gyrus and that p75NTR may play a role in anxiety-like behavior, specifically in female mice.

  20. Reduced Anxiety-Like Behavior and Altered Hippocampal Morphology in Female p75NTR(exon IV-/-) Mice.

    Science.gov (United States)

    Puschban, Zoe; Sah, Anupam; Grutsch, Isabella; Singewald, Nicolas; Dechant, Georg

    2016-01-01

    The presence of the p75 neurotrophin receptor (p75NTR) in adult basal forebrain cholinergic neurons, precursor cells in the subventricular cell layer and the subgranular cell layer of the hippocampus has been linked to alterations in learning as well as anxiety- and depression- related behaviors. In contrast to previous studies performed in a p75NTR(exon III-/-) model still expressing the short isoform of the p75NTR, we focused on locomotor and anxiety-associated behavior in p75NTR(exon IV-/-) mice lacking both p75NTR isoforms. Comparing p75NTR(exon IV-/-) and wildtype mice for both male and female animals showed an anxiolytic-like behavior as evidenced by increased central activities in the open field paradigm and flex field activity system as well as higher numbers of open arm entries in the elevated plus maze test in female p75NTR knockout mice. Morphometrical analyses of dorsal and ventral hippocampus revealed a reduction of width of the dentate gyrus and the granular cell layer in the dorsal but not ventral hippocampus in male and female p75NTR(exon IV-/-) mice. We conclude that germ-line deletion of p75NTR seems to differentially affect morphometry of dorsal and ventral dentate gyrus and that p75NTR may play a role in anxiety-like behavior, specifically in female mice. PMID:27313517

  1. STUDY ON THE CRYSTALLIZATION BEHAVIOR OF PLA/PBS/DCP REACTIVE BLENDS%PLA/PBS/DCP反应共混体系的结晶行为研究

    Institute of Scientific and Technical Information of China (English)

    季得运; 刘正英; 兰小蓉; 吴枫; 华笋; 杨鸣波

    2012-01-01

    The poly ( lactic acid ) /poly ( butylene succinate ) ( PLA/PBS ) blends with and without dicumyl peroxide ( DCP) were prepared by melt mixing and the crystallization behaviors of the blends were investigated using a differential scanning calorimeter ( DSC ) . The results showed that the crystallization ability of PLA was not improved when it was blended with PBS because of the higher molecular weight of PBS than that of PLA in this research,which was not in accord with results of some other researchers. However,the crystallization ability of PLA in the reactive blends (PLA/PBS/DCP) was promoted after the addition of different amount of DCP, because some crosslinked ( or grafted) structures were generated in this matrix, and the crosslinked ( or grafted) structures acted as nucleating points. It is found that when the content of DCP was from 0. 1 phr to 0. 3 phr, the crystallization was mostly caused by PBS, and this crystallization reduced with increasing the DCP content. When the content of DCP was above 0. 3 phr,that is to say,PLA began to crystallize when the DCP content was 0. 4 phr. The crystallization of PLA was enhanced with further increasing the content of DCP,while the crystallization of PBS was weakened in the same situation. In other words, the crystallization behavior of PLA and PBS in the PLA/PBS/DCP reactive blends was mostly depended on the DCP content.%通过熔融共混法制备了一系列聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)物理共混试样及PLA/PBS/过氧化二异丙苯(DCP)反应共混试样,采用示差扫描量热分析(DSC)法研究了物理共混试样结晶行为及反应共混试样的特殊结晶行为.结果发现,PLA与PBS的物理共混并未改善PLA的结晶性,而PLA/PBS/DCP反应共混时生成的交联/支化结构可起到异相成核作用,从而明显改善了反应共混体系的结晶性能,且随着DCP含量的增加,共混体系中两相结晶行为出现交替变化.

  2. Crystal Structure and Catalytic Behavior in Olefin Epoxidation of a One-Dimensional Tungsten Oxide/Bipyridine Hybrid.

    Science.gov (United States)

    Amarante, Tatiana R; Antunes, Margarida M; Valente, Anabela A; Paz, Filipe A Almeida; Pillinger, Martyn; Gonçalves, Isabel S

    2015-10-19

    The tungsten oxide/2,2'-bipyridine hybrid material [WO3(2,2'-bpy)]·nH2O (n = 1-2) (1) has been prepared in near quantitative yield by the reaction of H2WO4, 2,2'-bpy, and H2O in the mole ratio of ca. 1:2:700 at 160 °C for 98 h in a rotating Teflon-lined digestion bomb. The solid-state structure of 1 was solved and refined through Rietveld analysis of high-resolution synchrotron X-ray diffraction data collected for the microcrystalline powder. The material, crystallizing in the orthorhombic space group Iba2, is composed of a one-dimensional organic-inorganic hybrid polymer, ∞(1)[WO3(2,2'-bpy)], topologically identical to that found in the previously reported anhydrous phases [MO3(2,2'-bpy)] (M = Mo, W). While in the latter the N,N'-chelated 2,2'-bpy ligands of adjacent corner-shared {MO4N2} octahedra are positioned on the same side of the 1D chain, in 1 the 2,2'-bpy ligands alternate above and below the chain. The catalytic behavior of compound 1 for the epoxidation of cis-cyclooctene was compared with that for several other tungsten- or molybdenum-based (pre)catalysts, including the hybrid polymer [MoO3(2,2'-bpy)]. While the latter exhibits superior performance when tert-butyl hydroperoxide (TBHP) is used as the oxidant, compound 1 is superior when aqueous hydrogen peroxide is used, allowing near-quantitative conversion of the olefin to the epoxide. With H2O2, compounds 1 and [MoO3(2,2'-bpy)] act as sources of soluble active species, namely, the oxodiperoxo complex [MO(O2)2(2,2'-bpy)], which is formed in situ. Compounds 1 and [WO(O2)2(2,2'-bpy)] (2) were further tested in the epoxidation of cyclododecene, trans-2-octene, 1-octene, (R)-limonene, and styrene. The structure of 2 was determined by single-crystal X-ray diffraction and found to be isotypical with the molybdenum analogue.

  3. Indentation Schmid factor and orientation dependence of nanoindentation pop-in behavior of NiAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tianlei [ORNL; Gao, Yanfei [ORNL; Bei, Hongbin [ORNL; George, Easo P [ORNL

    2011-01-01

    Instrumented nanoindentation techniques have been widely used to characterize the small-scale mechanical behavior of materials. The elastic-plastic transition during nanoindentation is often indicated by a sudden displacement burst (pop-in) in the measured load-displacement curve. In defect-free single crystals, the pop-in is believed to be the result of homogeneous dislocation nucleation because the maximum shear stress corresponding to the pop-in load approaches the theoretical strength of the materials and because the statistical distribution of pop-in stresses is consistent with what is expected for a thermally activated process of homogeneous dislocation nucleation. This paper investigates whether this process is affected by crystallography and stress components other than the resolved shear stress. A Stroh formalism coupled with the two-dimensional Fourier transformation is used to derive the analytical stress fields in elastically anisotropic solids under Hertzian contact, which allows the determination of an indentation Schmid factor, namely, the ratio of maximum resolved shear stress to the maximum contact pressure. Nanoindentation tests were conducted on B2-structured NiAl single crystals with different surface normal directions. This material was chosen because it deforms at room temperature by {110}<001> slip and thus avoids the complexity of partial dislocation nucleation. Good agreement is obtained between the experimental data and the theoretically predicted orientation dependence of pop-in loads based on the indentation Schmid factor. Pop-in load is lowest for indentation directions close to <111> and highest for those close to <001>. In nanoindentation, since the stress component normal to the slip plane is typically comparable in magnitude to the resolved shear stress, we find that the pressure sensitivity of homogeneous dislocation nucleation cannot be determined from pop-in tests. Our statistical measurements generally confirm the thermal

  4. Morphology and kinetics of polymorphic transformations in K{sub 0.965}Rb{sub 0.035}NO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nasirov, V. I.; Bairamov, R. B., E-mail: bayramov.razim@mail.ru; Nasirov, E. V. [Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

    2015-12-15

    Polymorphic transformations in K{sub 0.965}Rb{sub 0.035}NO{sub 3} single crystals have been investigated by optical microscopy and X-ray diffraction. The equilibrium temperature between modifications II and III of the crystal studied is determined to be T = 452 ± 0.5 K. It is found that polymorphic transformations are of the single crystal ↔ single crystal type and occur with the formation and growth of nuclei of new crystals in matrix ones at II ↔ III transformations. An empirical dependence of the growth rate of modification III on temperature is established in the form ϑ = ϑ = (–0.478ΔT + 0.712ΔT{sup 2}–0.00041ΔT{sup 3}) × 10{sup –2} cm/s (ΔT = T{sub tr}–T{sub 0}, where T{sub tr} is the transformation temperature and T{sub 0} is the equilibrium temperature)

  5. Voltage behavior along the irregular dendritic structure of morphologically and physiologically characterized vagal motoneurons in the guinea pig.

    Science.gov (United States)

    Nitzan, R; Segev, I; Yarom, Y

    1990-02-01

    1. Intracellular recordings from neurons in the dorsal motor nucleus of the vagus (vagal motoneurons, VMs) obtained in the guinea pig brain stem slice preparation were used for both horseradish peroxidase (HRP) labeling of the neurons and for measurements of their input resistance (RN) and time constant (tau 0). Based on the physiological data and on the morphological reconstruction of the labeled cells, detailed steady-state and compartmental models of VM were built and utilized to estimate the range of membrane resistivity, membrane capacitance, and cytoplasm resistivity values (Rm, Cm, and Ri, respectively) and to explore the integrative properties of these cells. 2. VMs are relatively small cells with a simple dendritic structure. Each cell has an average of 5.3 smooth (nonspiny), short (251 microns) dendrites with a low order (2) of branching. The average soma-dendritic surface area of VMs is 9,876 microns 2. 3. Electrically, VMs show remarkably linear membrane properties in the hyperpolarizing direction; they have an average RN of 67 +/- 23 (SD) M omega and a tau 0 of 9.4 +/- 4.1 ms. Several unfavorable experimental conditions precluded the possibility of faithfully recovering ("peeling") the first equalizing time constant (tau 1) and, thereby, of estimating the electrotonic length (Lpeel) of VMs. 4. Reconciling VM morphology with the measured RN and tau 0 through the models, assuming an Ri of 70 omega.cm and a spatially uniform Rm, yielded an Rm estimate of 5,250 omega.cm2 and a Cm of 1.8 microF/cm2. Peeling theoretical transients produced by these models result in an Lpeel of 1.35. Because of marked differences in the length of dendrites within a single cell, this value is larger than the maximal cable length of the dendrites and is twice as long as their average cable length. 5. The morphological and physiological data could be matched indistinguishably well if a possible soma shunt (i.e., Rm, soma less than Rm, dend) was included in the model. Although

  6. Crystal micromorphologies and forming voltage effect on resistance switching behaviors in Ti/Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7}/Pt devices

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yuchen; Song, Liwei; Hua, Lifang; Cai, Wenhui; Chen, Wei [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Zhao, Xu, E-mail: xzhao@hebtu.edu.cn [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-10-15

    Two Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7} (PSCMO)-based devices (Ti/PSCMO-1/Pt and Ti/PSCMO-2/Pt) have been prepared by pulsed laser deposition, and the micromorphology of the films can be controlled through the different deposition condition. PSCMO-1 film with a smaller grain size grows with a near-random arrangement, whereas columnar grains with a larger grain size appear in the Ti/PSCMO-2/Pt device. The I–V curves in Ti/PSCMO-2/Pt device show the higher resistance ratio and larger hysteresis than that in the Ti/PSCMO-1/Pt device without forming process. The electron transport property in the PSCMO-2 film shows the higher resistance and metal behavior in room temperature. By fitting the I–V curves, we found that the conduction process in Ti/PSCMO-1/Pt device is dominated by Schottky barrier mechanism, but the conduction behavior in Ti/PSCMO-2/Pt device are dominated by trap-charged space-charge-limited current (SCLC) mechanism. Interesting, after a forming process, the Ti/PSCMO-1/Pt device also displays the higher resistance ratio and larger hysteresis, which can be explained by SCLC mechanism. Our results suggest that the crystal micromorphology and grain size may play a critical role in oxygen vacancy movement, and result in the transformation of resistance switching along with a higher resistance ratio and larger hysteresis in the Ti/PSCMO-2/Pt device. - Highlights: • Two different Pr(Sr{sub 0.1}Ca{sub 0.9}){sub 2}Mn{sub 2}O{sub 7}-based devices have been prepared. • The device with larger grain and columnar arrangement shows higher resistance ratio. • Crystal morphologies and grain size play critical role in oxygen vacancy movement.

  7. Protein crystallization as a process step in a novel meso oscillatory flow reactor: study of lysozyme phase behavior

    OpenAIRE

    Castro, Filipa; Ferreira, António; Teixeira, J. A.; Rocha, Fernando

    2016-01-01

    In the present work, it is reported for the first time the study of the applicability of a novel meso oscillatory flow reactor (meso-OFR) for protein crystallization as a process step. Crystallization assays carried out in the designed device enabled to derive a two-dimensional lysozyme phase diagram (lysozyme concentration against sodium chloride concentration). Results evidence the formation of several types of crystals (different size and shape), with a strong influence of salt concentrati...

  8. Evolution and diversity in avian vocal system: an Evo-Devo model from the morphological and behavioral perspectives.

    Science.gov (United States)

    Matsunaga, Eiji; Okanoya, Kazuo

    2009-04-01

    Birds use various vocalizations to mark their territory and attract mates. Three groups of birds (songbirds, parrots, and hummingbirds) learn their vocalizations through imitation. In the brain of such vocal learners, there is a neural network called the song system specialized for vocal learning and production. In contrast, birds such as chickens and pigeons do not have such a neural network and can only produce innate sounds. Since each avian species shows distinct, genetically inherited vocal learning abilities that are related to its morphology, the avian vocal system is a good model for studying the evolution of functional neural circuits. Nevertheless, studies on avian vocalization from an evolutionary developmental-biological (Evo-Devo) perspective are scant. In the present review, we summarize the results of songbird studies and our recent work that used the Evo-Devo approach to understand the evolution of the avian vocal system.

  9. Phase behavior and rheological analysis of reverse liquid crystals and W/I2, W/H2 gel emulsions using an amphiphilic block copolymer.

    OpenAIRE

    May Masnou, Anna; Aramaki, Kenji; Gutiérrez González, José María, 1953-

    2011-01-01

    This article reports the phase behavior determi- nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural proper- ties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular ...

  10. Chronic administration of the neurotrophic agent cerebrolysin ameliorates the behavioral and morphological changes induced by neonatal ventral hippocampus lesion in a rat model of schizophrenia.

    Science.gov (United States)

    Vázquez-Roque, Rubén Antonio; Ramos, Brenda; Tecuatl, Carolina; Juárez, Ismael; Adame, Anthony; de la Cruz, Fidel; Zamudio, Sergio; Mena, Raúl; Rockenstein, Edward; Masliah, Eliezer; Flores, Gonzalo

    2012-01-01

    Neonatal ventral hippocampal lesion (nVHL) in rats has been widely used as a neurodevelopmental model to mimic schizophrenia-like behaviors. Recently, we reported that nVHLs result in dendritic retraction and spine loss in prefrontal cortex (PFC) pyramidal neurons and medium spiny neurons of the nucleus accumbens (NAcc). Cerebrolysin (Cbl), a neurotrophic peptide mixture, has been reported to ameliorate the synaptic and dendritic pathology in models of aging and neurodevelopmental disorder such as Rett syndrome. This study sought to determine whether Cbl was capable of reducing behavioral and neuronal alterations in nVHL rats. The behavioral analysis included locomotor activity induced by novel environment and amphetamine, social interaction, and sensoriomotor gating. The morphological evaluation included dendritic analysis by using the Golgi-Cox procedure and stereology to quantify the total cell number in PFC and NAcc. Behavioral data show a reduction in the hyperresponsiveness to novel environment- and amphetamine-induced locomotion, with an increase in the total time spent in social interactions and in prepulse inhibition in Cbl-treated nVHL rats. In addition, neuropathological analysis of the limbic regions also showed amelioration of dendritic retraction and spine loss in Cbl-treated nVHL rats. Cbl treatment also ameliorated dendritic pathology and neuronal loss in the PFC and NAcc in nVHL rats. This study demonstrates that Cbl promotes behavioral improvements and recovery of dendritic neuronal damage in postpubertal nVHL rats and suggests that Cbl may have neurotrophic effects in this neurodevelopmental model of schizophrenia. These findings support the possibility that Cbl has beneficial effects in the management of schizophrenia symptoms. PMID:21932359

  11. Chronic administration of the neurotrophic agent cerebrolysin ameliorates the behavioral and morphological changes induced by neonatal ventral hippocampus lesion in a rat model of schizophrenia.

    Science.gov (United States)

    Vázquez-Roque, Rubén Antonio; Ramos, Brenda; Tecuatl, Carolina; Juárez, Ismael; Adame, Anthony; de la Cruz, Fidel; Zamudio, Sergio; Mena, Raúl; Rockenstein, Edward; Masliah, Eliezer; Flores, Gonzalo

    2012-01-01

    Neonatal ventral hippocampal lesion (nVHL) in rats has been widely used as a neurodevelopmental model to mimic schizophrenia-like behaviors. Recently, we reported that nVHLs result in dendritic retraction and spine loss in prefrontal cortex (PFC) pyramidal neurons and medium spiny neurons of the nucleus accumbens (NAcc). Cerebrolysin (Cbl), a neurotrophic peptide mixture, has been reported to ameliorate the synaptic and dendritic pathology in models of aging and neurodevelopmental disorder such as Rett syndrome. This study sought to determine whether Cbl was capable of reducing behavioral and neuronal alterations in nVHL rats. The behavioral analysis included locomotor activity induced by novel environment and amphetamine, social interaction, and sensoriomotor gating. The morphological evaluation included dendritic analysis by using the Golgi-Cox procedure and stereology to quantify the total cell number in PFC and NAcc. Behavioral data show a reduction in the hyperresponsiveness to novel environment- and amphetamine-induced locomotion, with an increase in the total time spent in social interactions and in prepulse inhibition in Cbl-treated nVHL rats. In addition, neuropathological analysis of the limbic regions also showed amelioration of dendritic retraction and spine loss in Cbl-treated nVHL rats. Cbl treatment also ameliorated dendritic pathology and neuronal loss in the PFC and NAcc in nVHL rats. This study demonstrates that Cbl promotes behavioral improvements and recovery of dendritic neuronal damage in postpubertal nVHL rats and suggests that Cbl may have neurotrophic effects in this neurodevelopmental model of schizophrenia. These findings support the possibility that Cbl has beneficial effects in the management of schizophrenia symptoms.

  12. Comparison of the corrosion behavior and surface morphology of NiTi alloy and stainless steels in sodium chloride solution

    OpenAIRE

    Kožuh S.; Vrsalović L.; Gojić M.; Gudić S.; Kosec B.

    2016-01-01

    The corrosion behavior of NiTi alloy and stainless steels (AISI 316L and X2CrNiMoN22-5-3) in 0.9% sodium chloride (0.154 moll-1) solution was investigated using open circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Microstructural analyses before and after electrochemical tests were performed with the scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Th...

  13. SIMULATED THREE DIMENSIONAL MORPHOLOGICAL LANDSCAPE OF POLYMER SINGLE CRYSTALS BY PHASE-FIELD MODEL%聚合物单晶生长的三维相场模拟研究

    Institute of Scientific and Technical Information of China (English)

    王冬; 苗宗成; 王向轲; 曹晖

    2013-01-01

    The polymer crystallization process and mechanism were studied by computer simulation method. It is benefit to understand the crystallization kinetics by comparing the simulated results with the experimental results. Based on a nonconserved spatiotemporal Ginzburg-Landau equation TDGL model, a novel three dimensional phase field model was established by combining the cellular automaton method with the general phase field model. For simulating the real three dimensional polymer crystallization process, the cellular automaton method was modified by the different steric structures and discretization methods. The different steric structures or discretization methods are related to the lattice parameters of syndiotactic polypropylene single crystals and the crystal growth faces of polymer single crystals. It was suggested that the novel method is a way of building bridges between the diffusion equation and polymer characterization. Moreover, the diffusion equations are discretized according to the diffusion coefficient of every lattice site in various crystal growth faces,and the shape of lattice is selected based on the real proportion of the unit cell dimensions. Especially, the other physics parameters of syndiotactic polypropylene also were introduced into the phase field model. The spatio-temporal growth of syndiotactic polypropylene single crystals during isothermal crystallization was simulated by the novel three dimensional phase field model. Three dimensional numerical calculations are performed to elucidate the faceted single crystal growth including square, rectangular, lozenge-shaped, and hexagonal single crystals. The corresponding three dimensional results were illustrated by the MatLab. Our simulated patterns are in good agreement with the experimental morphologies, and the physical origin of polymer single crystal growth is discussed.%利用元胞自动机方法与相场模型的结合建立新型三维模拟相场模型.同时,为模拟真实的、三

  14. Electro-optical behavior of polymer cholesteric liquid crystal flake/fluid suspensions in a microencapsulation matrix

    Science.gov (United States)

    Marshall, Kenneth L.; Kimball, Erin; McNamara, Shari; Kosc, Tanya Z.; Trajkovska-Petkoska, Anka; Jacobs, Stephen D.

    2004-10-01

    When flakes of polymer cholesteric liquid crystals (PCLC's) are dispersed in a fluid host and subjected to an applied electric field, their bright, polarization-selective reflection color is extinguished as they undergo field-induced rotation. Maxwell-Wagner (interfacial) polarization is the underlying physical mechanism for flake motion and results from the large difference in dielectric properties of the flake and fluid hosts. Flake reorientation times can be as short as 300 ms to 400 ms at exceedingly low driving fields (10 to 100 mVrms/μm) and are dependent on flake size and shape, fluid host dielectric constant and viscosity, and drive-filed frequency and magnitude. These attributes make this new materials system of special interest in electro-optical and photonics applications, where reflective-mode operation, polarization selectivity, and low power consumption are of critical importance (e.g., reflective displays). Until very recently, the electro-optical reorientation of PCLC flakes has been studied only in sandwich-type cells using glass substrates. In this work, we report on the dc field-induced reorientation behavior of PCLC flakes contained in confined spherical or near-spherical fluid-filled cavities formed by microencapsulation of the flake/fluid host dispersion in a water-borne flexible binder. This PCLC flake-fluid host/binder emulsion is coated onto either rigid or flexible condutive-coated substrates and then overcaoted (uniformly or patterned) using a conductive emulsion or paint that is either absorbing (black) or reflecting (silver). In addition to providing a unique environment to study flake motion, this device geometry also extends the application scope of the technology to conformal, electrically switchable coatings for large planar areas and flexible media for information display applications (e.g., electronic paper).

  15. The Influence of Na2O on the Solidification and Crystallization Behavior of CaO-SiO2-Al2O3-Based Mold Flux

    Science.gov (United States)

    Gao, Jinxing; Wen, Guanghua; Sun, Qihao; Tang, Ping; Liu, Qiang

    2015-08-01

    The reaction between [Al] and SiO2 sharply increased the Al2O3 and decreased SiO2 contents in mold flux during the continuous casting of high-Al steels. These changes converted original CaO-SiO2-based flux into CaO-SiO2-Al2O3-based flux, promoting the crystallization and deteriorating the mold lubrication. Therefore, study on the solidification and crystallization behavior of CaO-SiO2-Al2O3-based mold flux, with the applicable fluidizers, is of importance. The effect of Na2O, predominantly used as the fluidizer in mold flux, on the solidification and crystallization behavior of CaO-SiO2-Al2O3-based mold flux needs to be investigated. In this study, a CaO-SiO2-Al2O3-based mold flux containing 6.5 wt pct Li2O was designed; the effect of Na2O on the solidification and crystallization behavior of these mold fluxes was investigated using the single hot thermocouple technique (SHTT) and the double hot thermocouple technique (DHTT). Moreover, the slag film obtained by a heat flux simulator was analyzed using X-ray diffraction (XRD). The results indicate that the solid fraction of molten slag (Fs) and the crystalline fraction of solid slag (Fc) in the mold slag films decrease with increasing Na2O content from 0 to 2 wt pct. However, Fs and Fc increased when the Na2O content increased from 2 to 6 wt pct. The critical cooling rates initially decreases and then increases with increasing Na2O content. The XRD analysis results show that LiAlO2 and CaF2 were the basic crystals for all the mold fluxes. Increasing the Na2O content both inhibits the Ca2Al2SiO7 formation and promotes the production of Ca12Al14O33, indicating that the mold lubrication deteriorated because of the high melting-point phase formation of Ca2Al2SiO7 in the CaO-SiO2-Al2O3-based mold flux containing 6.5 wt pct Li2O, without Na2O. The strong crystallization tendency also deteriorated the mold lubrication for the mold flux with a higher Na2O content. Therefore, the addition of Na2O was less than 2 wt pct in

  16. A pilot trial of integrated behavioral activation and sexual risk reduction counseling for HIV-uninfected men who have sex with men abusing crystal methamphetamine.

    Science.gov (United States)

    Mimiaga, Matthew J; Reisner, Sari L; Pantalone, David W; O'Cleirigh, Conall; Mayer, Kenneth H; Safren, Steven A

    2012-11-01

    Crystal methamphetamine use is a major driver behind high-risk sexual behavior among men who have sex with men (MSM). Prior work suggests a cycle of continued crystal methamphetamine use and high-risk sex due to loss of the ability to enjoy other activities, which appears to be a side effect of this drug. Behavioral activation (BA) is a treatment for depression that involves learning to reengage in life's activities. We evaluated a novel intervention for crystal methamphetamine abuse and high-risk sex in MSM, incorporating 10 sessions of BA with integrated HIV risk reduction counseling (RR). Forty-four subjects were screened, of whom 21 met initial entry criteria. A total of 19 participants enrolled; 16 completed an open-phase study of the intervention. Behavioral assessments were conducted at baseline, 3 months postbaseline, and 6 months postbaseline. Linear mixed effects regression models were fit to assess change over time. Mean unprotected anal intercourse (UAI) episodes decreased significantly from baseline to acute postintervention (β=-4.86; 95% confidence interval [CI]=-7.48, -2.24; p=0.0015) and from baseline to 6 months postbaseline (β=-5.07; 95% CI=-7.85, -2.29; p=0.0017; test of fixed effects χ(2)=16.59; df=2,13; p=0.0002). On average, there was a significant decrease over time in the number of crystal methamphetamine episodes in the past 3 months (χ(2)=22.43; df=2,15; p<0.0001), and the number of days of crystal methamphetamine use in the past 30 days (χ(2)=9.21; df=2,15; p=0.010). Statistically significant reductions in depressive symptoms and poly-substance use were also maintained. Adding behavioral activation to risk reduction counseling for MSM with problematic crystal methamphetamine use may augment the potency of a risk reduction intervention for this population. Due to the small sample size and time intensive intervention, future testing in a randomized design is necessary to determine efficacy, with subsequent effectiveness testing. PMID

  17. Isothermal Crystallization Behavior of Cocoa Butter at 17 and 20 °C with and without Limonene.

    Science.gov (United States)

    Rigolle, Annelien; Goderis, Bart; Van Den Abeele, Koen; Foubert, Imogen

    2016-05-01

    Differential scanning calorimetry and real-time X-ray diffraction using synchrotron radiation were used to elucidate isothermal cocoa butter crystallization at 17 and 20 °C in the absence and presence of different limonene concentrations. At 17 °C, a three-step crystallization process was visible for pure cocoa butter, whereby first an unknown structure with long spacings between a 2L and 3L structure was formed that rapidly transformed into the more stable α structure, which in turn was converted into more stable β' crystals. At 20 °C, an α-mediated β' crystallization was observed. The addition of limonene resulted in a reduction of the amount of unstable crystals and an acceleration of polymorphic transitions. At 17 °C, the crystallization process was accelerated due to the acceleration of the formation of more stable polymorphic forms, whereas there were insufficient α crystals for an α-mediated β' nucleation at 20 °C, resulting in a slower crystallization process.

  18. Research on the Influence of Pyrolysis Reaction Rate on Light Magnesium Carbonate Crystal Morphology%热解反应速率对轻质碳酸镁晶体形貌影响研究

    Institute of Scientific and Technical Information of China (English)

    万建军; 于博; 刘安双

    2013-01-01

    针对重镁水热解反应特点,采用抽真空降低系统中CO2气体分压的方式,加速重镁水热解反应正向反应速率.通过观察、对比一定热解温度,不同真空度下反应生成的轻质碳酸镁晶体型貌,得出结论:降低CO2气体分压,提高热解反应速率,会减缓轻质碳酸镁晶体型貌由棒状→片状→球状这一转变过程.当热解温度为50℃,提高反应速率,会促进轻质碳酸镁晶体团聚,反应速率越快,团聚现象越明显.%According to the characteristics of the heavy magnesium water pyrolysis and using vacuum to reduce the partial pressure of C02 gas in the system, the positive reaction rate of the pyrolysis reaction of heavy magnesium water is accelerated. By observation and comparison of light magnesium carbonate crystal morphology generated with certain pyrolysis temperature and different degree of vacuum, it can be concluded that the transition process of the light magnesium carbonate crystal morphology will slow down when reducing the partial pressure of C02 gas and increasing the rate of pyrolysis reaction. When the temperature of pyrolysis reaches 50 ℃ , the reunion of light magnesium carbonate crystal will be accelerated by improving the reaction rate. The faster the reaction rate is, the more obvious the reunion phenomenon is.

  19. Deltamethrin-mediated survival, behavior, and oenocyte morphology of insecticide-susceptible and resistant yellow fever mosquitos (Aedes aegypti).

    Science.gov (United States)

    Marriel, Nadja Biondine; Tomé, Hudson Vaner Ventura; Guedes, Raul Carvalho Narciso; Martins, Gustavo Ferreira

    2016-06-01

    Insecticide use is the prevailing control tactic for the mosquito Aedes aegypti, a vector of several human viruses, which leads to ever-increasing problems of insecticide resistance in populations of this insect pest species. The underlying mechanisms of insecticide resistance may be linked to the metabolism of insecticides by various cells, including oenocytes. Oenocytes are ectodermal cells responsible for lipid metabolism and detoxification. The goal of this study was to evaluate the sublethal effects of deltamethrin on survival, behavior, and oenocyte structure in the immature mosquitoes of insecticide-susceptible and resistant strains of A. aegypti. Fourth instar larvae (L4) of both strains were exposed to different concentrations of deltamethrin (i.e., 0.001, 0.003, 0.005, and 0.007 ppm). After exposure, L4 were subjected to behavioral bioassays. Insecticide effects on cell integrity after deltamethrin exposure (at 0.003 or 0.005 ppm) were assessed by processing pupal oenocytes for transmission electron microscopy or TUNEL reaction. The insecticide resistant L4 survived all the tested concentrations, whereas the 0.007-ppm deltamethrin concentration had lethal effects on susceptible L4. Susceptible L4 were lethargic and exhibited less swimming activity than unexposed larvae, whereas the resistant L4 were hyperexcited following exposure to 0.005 ppm deltamethrin. No sublethal effects and no significant cell death were observed in the oenocytes of either susceptible or resistant insects exposed to deltamethrin. The present study illustrated the different responses of susceptible and resistant strains of A. aegypti following exposure to sublethal concentration of deltamethrin, and demonstrated how the behavior of the immature stage of the two strains varied, as well as oenocyte structure following insecticide exposure. PMID:26943998

  20. Influence of purified multiwalled carbon nanotubes on the mechanical and morphological behavior in poly (L-lactic acid) matrix.

    Science.gov (United States)

    Leal, C V; Martinez, D S T; Más, B A; Alves, O L; Duek, E A R

    2016-06-01

    Poly (L-latic acid) (PLLA) is a bioresorbable polymer widely used as a biomaterial, but its fragility can limit its use. An alternative is to produce polymer nanocomposites, which can enhance the mechanical properties of polymeric matrix, resulting in a material with differentiated properties. In this work, PLLA based nanocomposites containing 0.25, 0.5 and 1.0wt% of purified multiwalled carbon nanotubes (p-MWCNTs) were prepared by the solvent casting method. The morphology and mechanical properties results show an improvement in strain at break for 0.25 and 0.5wt% p-MWCNTs and an increase in stiffness and elastic modulus for all compositions. Nanocomposites presented a p-MWCNTs agglomeration; however, there was a good stress transfer between PLLA and p-MWCNTs, which was confirmed by the increase in the hardness and elastic modulus. Atomic force microscopy analysis indicated an increase in roughness after nanotube addition. The in vitro biological study showed that PLLA/p-MWCNTs nanocomposites are cytocompatible with osteoblasts cells. The capacity of PLLA nanocomposites to stimulate osteogenesis was investigated by alkaline phosphatase (ALP) activity assay. Higher ALP activity was found on osteoblasts cultured on nanocomposites with 0.25 and 0.5wt% p-MWCNT compared to neat PLLA, confirming that PLLA cytocompatibility was improved on these compositions. Finally, our results showed that by a simple and inexpensive solvent casting method, it is possible to manufacture biofunctional nanocomposites devices with potential for orthopedic applications. PMID:27038896