Influence of substitution of La by Ce on the glass forming ability and crystallization behavior of Al–Ni–La alloys

International Nuclear Information System (INIS)

Zhang, Z.; Xiong, X.Z.; Zhou, W.; Li, J.F.

2013-01-01

Highlights: •Wedge-shaped samples were suction cast with casting conditions controlled. •Partial substitution of La by Ce decreases the GFA of Al 85.5 Ni 9.5 La 5 . •Partial substitution of La by Ce increases the GFA of other Al–Ni–La alloys. •The GFA was analyzed from the thermodynamic and topological points of view. -- Abstract: Wedge-shaped samples of Al–Ni–(La–Ce) alloys were suction cast under an identical preparation condition, and their glass forming abilities (GFAs) and crystallization behaviors were compared. It was revealed that the partial substitution of La by Ce decreases the GFA of Al 85.5 Ni 9.5 La 5 alloy but increases the GFAs of Al 87.5 Ni 7.5 La 5 , Al 86.5 Ni 8.5 La 5 , Al 86 Ni 9 La 5 and Al 86 Ni 9.5 La 4.5 alloys. Meantime the crystallization behavior significantly changes. The optimal substitution content of La for glass formation depends on the composition of the base alloy. The lower the Ni content in the base alloy, the more the La content to be substituted. The GFA change with the substitution content is determined by the atomic packing efficiencies of the La (Ce)-centered clusters

The role of crystal orientation and surface proximity in the self-similar behavior of deformed Cu single crystals

Energy Technology Data Exchange (ETDEWEB)

Pang, Judy W.L., E-mail: pangj@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Ice, Gene E. [Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Behtel Valley Road, Oak Ridge, TN 37831 (United States); Liu Wenjun [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2010-11-25

We report on novel 3D spatially resolved X-ray diffraction microscopy studies of self-affine behavior in deformed single crystals. This study extends surface profile measurements of self-affined morphology changes in single crystals during deformation to include local lattice rotations and sub-surface behavior. Investigations were made on the spatial correlation of the local lattice rotations in 8% tensile deformed Cu single crystals oriented with [1 2 3], [1 1 1] and [0 0 1] axes parallel to the tensile axis. The nondestructive depth-resolved measurements were made over a length scale of one to hundreds of micrometers. Self-affined correlation was found both at the surface and below the surface of the samples. A universal exponent for the power-law similar to that observed with surface profile methods is found at the surface of all samples but crystallographically sensitive changes are observed as a function of depth. Correlation lengths of the self-affine behavior vary with the [1 2 3] crystal exhibiting the longest self-affine length scale of 70 {mu}m with only 18 {mu}m for the [1 1 1] and [0 0 1] crystals. These measurements illuminate the transition from surface-like to bulk-like deformation behavior and provide new quantitative information to guide emerging models of self-organized structures in plasticity.

Influence of substitution of La by Ce on the glass forming ability and crystallization behavior of Al–Ni–La alloys

Energy Technology Data Exchange (ETDEWEB)

Zhang, Z.; Xiong, X.Z.; Zhou, W.; Li, J.F., E-mail: jfli@sjtu.edu.cn

2013-11-05

Highlights: •Wedge-shaped samples were suction cast with casting conditions controlled. •Partial substitution of La by Ce decreases the GFA of Al{sub 85.5}Ni{sub 9.5}La{sub 5}. •Partial substitution of La by Ce increases the GFA of other Al–Ni–La alloys. •The GFA was analyzed from the thermodynamic and topological points of view. -- Abstract: Wedge-shaped samples of Al–Ni–(La–Ce) alloys were suction cast under an identical preparation condition, and their glass forming abilities (GFAs) and crystallization behaviors were compared. It was revealed that the partial substitution of La by Ce decreases the GFA of Al{sub 85.5}Ni{sub 9.5}La{sub 5} alloy but increases the GFAs of Al{sub 87.5}Ni{sub 7.5}La{sub 5}, Al{sub 86.5}Ni{sub 8.5}La{sub 5}, Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9.5}La{sub 4.5} alloys. Meantime the crystallization behavior significantly changes. The optimal substitution content of La for glass formation depends on the composition of the base alloy. The lower the Ni content in the base alloy, the more the La content to be substituted. The GFA change with the substitution content is determined by the atomic packing efficiencies of the La (Ce)-centered clusters.

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.

Crystallization behavior of partially miscible biodegradable poly(butylene succinate)/poly(ethylene succinate) blends

International Nuclear Information System (INIS)

He, Yi-Song; Zeng, Jian-Bing; Li, Shao-Long; Wang, Yu-Zhong

2012-01-01

Graphical abstract: Crystallization rate of PBS in the blends decreased first and then increased with increase in PES content, and that of PES increased steadily with increase in PBS content. The rich component formed a continuous phase and the other formed a dispersed phase of the blend. Crystal structures of PBS and PES were almost unchanged after blending with each other. Highlights: ► PBS/PES blend systems are partially miscible. ► Blending did not change the crystallization mechanisms of PBS and PES not affects the crystallization rates. ► The rich component formed the continuous phase while the poor component formed the dispersed phase of the blends. ► Crystal structures of PBS and PES were almost unchanged after blending with each other. - Abstract: Biodegradable blend of poly(butylene succinate) (PBS) and poly(ethylene succinate) (PES) was prepared by solution blending and casting method with chloroform as a mutual solvent. Miscibility of the blends was investigated by differential scanning calorimetry (DSC). The results indicated that PBS and PES were partially miscible. Crystallization kinetics, crystalline morphology and crystal structure of the blends were studied by DSC, polarized optical microscope (POM), and wide-angle X-ray diffraction (WAXD), respectively. Nonisothermal and isothermal crystallization kinetics suggested that the crystallizability of PBS in the blends decreased first and then increased with increase in PES content, and that of PES increased steadily with increase in PBS content. POM observation illustrated that the rich component formed a continuous phase and the other formed a dispersed phase. The results of WAXD indicated that the crystal structures of PBS and PES were almost unchanged before and after blending, since the positions of characteristic diffraction peaks of both components remain almost unchanged.

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

Crystallization and Martensitic Transformation Behavior of Ti-Ni-Si Alloy Ribbons Prepared via Melt Spinning.

Science.gov (United States)

Park, Ju-Wan; Kim, Yeon-Wook; Nam, Tae-Hyun

2018-09-01

Ti-(50-x)Ni-xSi (at%) (x = 0.5, 1.0, 3.0, 5.0) alloy ribbons were prepared via melt spinning and their crystallization procedure and transformation behavior were investigated using differential scanning calorimtry, X-ray diffraction, and transmission electron microscopy. Ti-Ni-Si alloy ribbons with Si content less than 1.0 at% were crystalline, whereas those with Si content more than 3.0 at% were amorphous. Crystallization occurred in the sequence of amorphous →B2 → B2 → Ti5Si4 + TiNi3 → B2 + Ti5Si4 + TiNi3 + TiSi in the Ti-47.0Ni-3.0Si alloy and amorphous →R → R + Ti5Si4 + TiNi3 → R + Ti5Si4 + TiNi3 + TiSi in the Ti-45.0Ni-5.0Si alloy. The activation energy for crystallization was 189 ±8.6 kJ/mol for the Ti-47Ni-3Si alloy and 212±8.6 kJ/mol for the Ti-45Ni-5Si alloy. One-stage B2-R transformation behavior was observed in Ti-49.5Ni-0.5Si, Ti-49.0Ni-1.0Si, and Ti-47.0Ni- 3.0Si alloy ribbons after heating to various temperatures in the range of 873 K to 1073 K. In the Ti-45.0Ni-5.0Si alloy, one-stage B2-R transformation occurred after heating to 893 K, two-stage B2-R-B19' occurred after heating to 973 K, and two-stage B2-R-B19' occurred on cooling and one-stage B19'-B2 occurred on heating, after heating to 1073 K.

Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (-)-N-Methylephedrine.

Science.gov (United States)

Tulashie, Samuel Kofi; Polenske, Daniel; Seidel-Morgenstern, Andreas; Lorenz, Heike

2016-11-01

This work involves the study of the solid-phase and solution crystallization behavior of the N-methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed. Copyright © 2016. Published by Elsevier Inc.

Utilization of High-Temperature Slags From Metallurgy Based on Crystallization Behaviors

Science.gov (United States)

Sun, Yongqi; Zhang, Zuotai

2018-05-01

Here, following the principle of modifying crystallization behaviors, including avoidance and optimization, we review recent research on the utilization of hot slags. Because of the high-temperature property (1450-1650°C), the utilization of hot slags are much different from that of other wastes. We approach this issue from two main directions, namely, material recycling and heat utilization. From the respect of material recycling, the utilization of slags mainly follows total utilization and partial utilization, whereas the heat recovery from slags follows two main paths, namely, physical granulation and chemical reaction. The effective disposal of hot slags greatly depends on clarifying the crystallization behaviors, and thus, we discuss some optical techniques and their applicable scientific insights. For the purpose of crystallization avoidance, characterizing the glass-forming ability of slags is of great significance, whereas for crystallization modification, the selection of chemical additives and control of crystallization conditions comprise the central routes.

Ethylbenzene Disproportionation on HZSM-5 Zeolite : The Effect of Aluminum Content and Crystal Size on the Selectivity for p-Diethylbenzene

Directory of Open Access Journals (Sweden)

Velasco N.D.

1998-01-01

Full Text Available The aim of this work was to verify the effect of MFI aluminum content and crystal size on the selectivity for para-diethylbenzene during ethylbenzene disproportionation. It was observed that the para-diethylbenzene selectivity increased as MFI crystal size increased. The increase in aluminum content caused a decrease in the selectivity for para-diethylbenzene. However, for crystals larger than 8 m m, the decrease in aluminum content had little influence on the selectivity for para-diethylbenzene. The results can be explained by the number of active aluminum sites on the external surface of the crystals.

Effects of quartz on crystallization behavior of mold fluxes and microstructural characteristics of flux film.

Science.gov (United States)

Lei, Liu; Xiuli, Han; Mingduo, Li; Di, Zhang

2018-01-01

Mold fluxes are mainly prepared using cement clinker, quartz, wollastonite, borax, fluorite, soda ash and other mineral materials. Quartz, as one of the most common and essential materials, was chosen for this study to analyze itseffects on crystallization temperature, critical cooling rate, crystal incubation time, crystallization ratio and phases of flux film. We used the research methods of process mineralogy with the application of the single hot thermocouple technique, heat flux simulator, polarizing microscope, X-ray diffraction, etc. Results: By increasing the quartz content from 16 mass% to 24 mass%, the crystallization temperature, critical cooling rate and crystallization ratio of flux film decreased, and the crystal incubation time was extended. Meanwhile, the mineralogical structure of the flux film changed, with a large amount of wollastonite precipitation and a significant decrease in the cuspidine content until it reached zero. This showed a steady decline in the heat transfer control capacity of the flux film. The reason for the results above is that, by increasing the quartz content, the silicon-oxygen tetrahedron network structure promoted a rise in viscosity and restrained ion migration, inhibiting crystal nucleation and growth, leading to the weakening of the crystallization and a decline in the crystallization ratio.

Dehydration and crystallization kinetics of zirconia-yttria gels

International Nuclear Information System (INIS)

Ramanathan, S.; Muraleedharan, R.V.; Roy, S.K.; Nayar, P.K.K.

1995-01-01

Zirconia and zirconia-yttria gels containing 4 and 8 mol% yttria were obtained by coprecipitation and drying at 373 K. The dehydration and crystallization behavior of the dried gels was studied by DSC, TG, and XRD. The gels undergo elimination of water over a wide temperature range of 373--673 K. The peak temperature of the endotherm corresponding to dehydration and the kinetic constants for the process were not influenced by the yttria content of the gel. The enthalpy of dehydration observed was in good agreement with the heat of vaporization data. The dehydration was followed by a sharp exothermic crystallization process. The peak temperature of the exotherm and the activation energy of the process increased with an increase in yttria content, while the enthalpy of crystallization showed a decrease. The ''glow effect'' reduced with increasing yttria content. Pure zirconia crystallizes in the tetragonal form while the zirconia containing 4 and 8 mol% yttria appears to crystallize in the cubic form

Relationships between the morphology and thermoresponsive behavior in micro/nanostructured thermosetting matrixes containing a 4'-(hexyloxy)-4-biphenylcarbonitrile liquid crystal.

Science.gov (United States)

Tercjak, Agnieszka; Mondragon, Iñaki

2008-10-07

Meso/nanostructured thermoresponsive thermosetting materials based on an epoxy resin modified with two different molecular weight amphiphilic poly(styrene- block-ethylene oxide) block copolymers (PSEO) and a low molecular weight liquid crystal, 4'-(hexyloxy)-4-biphenylcarbonitrile (HOBC), were investigated. A strong influence of the addition of PSEO on the morphology generated in HOBC--(diglicydyl ether of bisphenol A epoxy resin/ m-xylylenediamine) was detected, especially in the case of the addition of PSEO block copolymers with a higher PEO-block content and a lower molecular weight. The morphologies generated in the ternary systems also influenced the thermoresponsive behavior of the HOBC separated phase provoked by applying an external field, such as a temperature gradient and an electrical field. Thermal analysis of the investigated materials allowed for a better understanding of the relationships between generated morphology/thermo-optical properties/PSEO:HOBC ratio, and HOBC content. Controlling the relationship between the morphology and thermoresponsive behavior in micro/nanostructured thermosetting materials based on a 4'-(hexyloxy)-4-biphenylcarbonitrile liquid crystal allows the development of materials which can find application in thermo- and in some cases electroresponsive devices, with a high contrast ratio between transparent and opaque states.

Effect of the Cu and Ni content on the crystallization temperature and crystallization mechanism of La–Al–Cu(Ni metallic glasses

Directory of Open Access Journals (Sweden)

Peiyou Li

2016-02-01

Full Text Available The effect of the Cu and Ni content on the crystallization mechanism and the crystallization temperatures of La–Al–Cu(Ni metallic glasses (MGs was studied by differential scanning calorimetry (DSC. The experimental results have shown that the DSC curves obtained for the La–Al–Cu and La–Al–Ni MGs exhibit two and three crystallization temperatures, respectively. The crystallization temperatures of the La–Al–Cu and La–Al–Ni MGs result from the merging and splitting of thermal events related to the corresponding eutectic atomic pairs in the La72Cu28 and La81.6Al18.4 MGs, and La72Ni28 and La81.6Al18.4 MGs, respectively. In addition, Al- and Ni-containing clusters with weak or strong atomic interaction in the Al–Ni atomic pairs strongly affect the crystallization mechanism and thus the crystallization temperature of La–Al–Ni MGs. This study provides a novel understanding of the relation between the crystallization temperature and the underlying crystallization mechanisms in La–Al–Cu(Ni MGs.

Effects of B{sub 2}O{sub 3} content and sintering temperature on crystallization and microstructure of CBS glass–ceramic coatings

Energy Technology Data Exchange (ETDEWEB)

Li, Pengyang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials and Engneering, Beihang University, Beijing 100191 (China); Liu, Jianggao; Feng, Mengjie; Yang, Xinwang [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

2015-11-30

Graphical abstract: (a) TEM photogram of CG3 sintered at 800 °C, crystals are obvious; (b) the XRD patterns of CG3 glass samples sintered at various temperatures; (c) SEM photogram of CG3 sintered at 800 °C; (d) Kissinger, Augis–Bennett and Ozawa kinetics plots of CG3 glass samples. - Highlights: • Combining sol–gel method with direct sintering method to reduce the temperature of coatings formation. • Characterizing CaO–SiO{sub 2}–B{sub 2}O{sub 3} glass–ceramic coatings on porous substrates. • Surface crystallization of CBS glass–ceramic coatings: nucleation and kinetics. • Activation energies for crystal growth in CBS glass–ceramics with different contents of B{sub 2}O{sub 3}. - Abstract: Borosilicate glass–ceramics precursors with varying compositional ratios in the CaO–SiO{sub 2}–B{sub 2}O{sub 3} (CBS) system were synthesized by sol–gel method. The precursors were calcined at 1200 °C for 2 h to form glass powders. The glass–ceramics were prepared by overlaying glass slurries on the substrates before sintering at different temperatures. The as-prepared glasses and glass–ceramics were characterized by differential scanning calorimetry and X-ray diffraction. The crystallization activation energies (E{sub c}) were calculated using the Kissinger method from DSC results. The morphology and crystallization behavior of the glass–ceramics were monitored by scanning electron microscopy. Both glass transition and crystallization temperatures decreased, however, the metastable zone increased. The E{sub c} values of CBS glasses and glass–ceramics were 254.1, 173.2 and 164.4 kJ/mol with increasing B{sub 2}O{sub 3} content, whereas that of the calcined G3 glass was 104.9 kJ/mol. Finally, the coatings were prepared at a low temperature (700 °C). The crystals that grew on the surface of multilayer coatings demonstrated heterogeneous surface nucleation and crystallization after heat-treatment from 700 °C to 850 °C for 4 h.

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.

Crystallization behavior of (1 - x)Li2O.xNa2O.Al2O3.4SiO2 glasses

International Nuclear Information System (INIS)

Wang, Moo-Chin; Cheng, Chih-Wei; Chang, Kuo-Ming; Hsi, Chi-Shiung

2010-01-01

The crystallization behavior of the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and energy dispersive spectroscopy (EDS). The crystalline phase was composed of β-spodumene. The isothermal crystallization kinetics of β-spodumene from the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses has also been studied by a quantitative X-ray diffraction method. The activation energy of β-spodumene formation decreases from 359.2 to 317.8 kJ/mol when the Na 2 O content increases from 0 to 0.4 mol and it increases from 317.8 to 376.9 kJ/mol when the Na 2 O content increases from 0.4 to 0.6 mol. The surface nucleation and plate-like growth were dominant in the crystallization of the (1 - x)Li 2 O.xNa 2 O.Al 2 O 3 .4SiO 2 glasses.

UHMW Ziegler–Natta polyethylene: Synthesis, crystallization, and melt behavior

KAUST Repository

Atiqullah, Muhammad

2017-04-26

The fabrication of normal and UHMW PE end-products involves melting and crystallization of the polymer. Therefore, the melt behavior and crystallization of as-synthesized UHMW PE, and NMW PE and E-1-hexene copolymer have been studied using a new nonisothermal crystallization model, Flory\\'s equilibrium theory and ethylene sequence length distribution concept (SLD), Gibbs–Thompson equation, and DSC experiments. By using this approach, the effects of MW, 1-hexene incorporation, ethylene SLD, the level of undercooling θ, and crystal surface free energy D on crystallite stability, relative crystallinity α, instantaneous crystallinity χ, the crystallization kinetic triplet, crystallization entropy, and lamellar thickness distribution (LTD) have been evaluated. Consequently, this study reports insightful new results, interpretations, and explanations regarding the melting and crystallization of the aforementioned polymers. The UHMW PE results significantly differ from the NMW PE and E-1-hexene copolymer ones. Ethylene sequences shorter than the so called minimum crystallizable ethylene sequence length, irrespective of E-1-hexene copolymer MW, can also crystallize. Additionally, the polymer preparation shows that the catalyst coordination environment and symmetry, as well as achiral ethylene versus prochiral α-olefin steric encumbrance and competitive diffusion affect the synthesis of UHMW PE, particularly the corresponding UHMW copolymers.

Mutual interaction between high and low stereo-regularity components for crystallization and melting behaviors of polypropylene blend fibers

Science.gov (United States)

Kawai, Kouya; Kohri, Youhei; Takarada, Wataru; Takebe, Tomoaki; Kanai, Toshitaka; Kikutani, Takeshi

2016-03-01

Crystallization and melting behaviors of blend fibers of two types of polypropylene (PP), i.e. high stereo-regularity/high molecular weight PP (HPP) and low stereo-regularity/low molecular weight PP (LPP), was investigated. Blend fibers consisting of various HPP/LPP compositions were prepared through the melt spinning process. Differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC) and wide-angle X-ray diffraction (WAXD) analysis were applied for clarifying the crystallization and melting behaviors of individual components. In the DSC measurement of blend fibers with high LPP composition, continuous endothermic heat was detected between the melting peaks of LPP at around 40 °C and that of HPP at around 160 °C. Such endothermic heat was more distinct for the blend fibers with higher LPP composition indicating that the melting of LPP in the heating process was hindered because of the presence of HPP crystals. On the other hand, heat of crystallization was detected at around 90 °C in the case of blend fibers with LPP content of 30 to 70 wt%, indicating that the crystallization of HPP component was taking place during the heating of as-spun blend fibers in the DSC measurement. Through the TMDSC analysis, re-organization of the crystalline structure through the simultaneous melting and re-crystallization was detected in the cases of HPP and blend fibers, whereas re-crystallization was not detected during the melting of LPP fibers. In the WAXD analysis during the heating of fibers, amount of a-form crystal was almost constant up to the melting in the case of single component HPP fibers, whereas there was a distinct increase of the intensity of crystalline reflections from around 100 °C, right after the melting of LPP in the case of blend fibers. These results suggested that the crystallization of HPP in the spinning process as well as during the conditioning process after spinning was hindered by the presence of LPP.

Mutual interaction between high and low stereo-regularity components for crystallization and melting behaviors of polypropylene blend fibers

International Nuclear Information System (INIS)

Kawai, Kouya; Takarada, Wataru; Kikutani, Takeshi; Kohri, Youhei; Takebe, Tomoaki; Kanai, Toshitaka

2016-01-01

Crystallization and melting behaviors of blend fibers of two types of polypropylene (PP), i.e. high stereo-regularity/high molecular weight PP (HPP) and low stereo-regularity/low molecular weight PP (LPP), was investigated. Blend fibers consisting of various HPP/LPP compositions were prepared through the melt spinning process. Differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC) and wide-angle X-ray diffraction (WAXD) analysis were applied for clarifying the crystallization and melting behaviors of individual components. In the DSC measurement of blend fibers with high LPP composition, continuous endothermic heat was detected between the melting peaks of LPP at around 40 °C and that of HPP at around 160 °C. Such endothermic heat was more distinct for the blend fibers with higher LPP composition indicating that the melting of LPP in the heating process was hindered because of the presence of HPP crystals. On the other hand, heat of crystallization was detected at around 90 °C in the case of blend fibers with LPP content of 30 to 70 wt%, indicating that the crystallization of HPP component was taking place during the heating of as-spun blend fibers in the DSC measurement. Through the TMDSC analysis, re-organization of the crystalline structure through the simultaneous melting and re-crystallization was detected in the cases of HPP and blend fibers, whereas re-crystallization was not detected during the melting of LPP fibers. In the WAXD analysis during the heating of fibers, amount of a-form crystal was almost constant up to the melting in the case of single component HPP fibers, whereas there was a distinct increase of the intensity of crystalline reflections from around 100 °C, right after the melting of LPP in the case of blend fibers. These results suggested that the crystallization of HPP in the spinning process as well as during the conditioning process after spinning was hindered by the presence of LPP.

Mutual interaction between high and low stereo-regularity components for crystallization and melting behaviors of polypropylene blend fibers

Energy Technology Data Exchange (ETDEWEB)

Kawai, Kouya; Takarada, Wataru; Kikutani, Takeshi, E-mail: kikutani.t.aa@m.titech.ac.jp [Department of Organic and Polymeric Materials, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro-ku, Tokyo 152-8552 (Japan); Kohri, Youhei; Takebe, Tomoaki [Performance Materials Laboratories, Idemitsu Kosan Co.,Ltd. (Japan); Kanai, Toshitaka [KT Polymer (Japan)

2016-03-09

Crystallization and melting behaviors of blend fibers of two types of polypropylene (PP), i.e. high stereo-regularity/high molecular weight PP (HPP) and low stereo-regularity/low molecular weight PP (LPP), was investigated. Blend fibers consisting of various HPP/LPP compositions were prepared through the melt spinning process. Differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC) and wide-angle X-ray diffraction (WAXD) analysis were applied for clarifying the crystallization and melting behaviors of individual components. In the DSC measurement of blend fibers with high LPP composition, continuous endothermic heat was detected between the melting peaks of LPP at around 40 °C and that of HPP at around 160 °C. Such endothermic heat was more distinct for the blend fibers with higher LPP composition indicating that the melting of LPP in the heating process was hindered because of the presence of HPP crystals. On the other hand, heat of crystallization was detected at around 90 °C in the case of blend fibers with LPP content of 30 to 70 wt%, indicating that the crystallization of HPP component was taking place during the heating of as-spun blend fibers in the DSC measurement. Through the TMDSC analysis, re-organization of the crystalline structure through the simultaneous melting and re-crystallization was detected in the cases of HPP and blend fibers, whereas re-crystallization was not detected during the melting of LPP fibers. In the WAXD analysis during the heating of fibers, amount of a-form crystal was almost constant up to the melting in the case of single component HPP fibers, whereas there was a distinct increase of the intensity of crystalline reflections from around 100 °C, right after the melting of LPP in the case of blend fibers. These results suggested that the crystallization of HPP in the spinning process as well as during the conditioning process after spinning was hindered by the presence of LPP.

Effect of carbon content on the microstructure and creep properties of a 3rd generation single crystal nickel-base superalloy

Energy Technology Data Exchange (ETDEWEB)

Li, X.W.; Liu, T. [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, L., E-mail: wangli@imr.ac.cn [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Liu, X.G.; Lou, L.H. [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, J. [Superalloys Division, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2015-07-15

Effect of carbon content on the microstructure and creep properties of a 3rd generation single crystal nickel-base superalloy has been investigated by the scanning electron microscope, X-ray computed tomography and electron probe microanalyzer. With the increase of the carbon content, MC carbides evolve from octahedral to well-developed dendrite, which promotes the formation of microporosity. Moreover, the volume fraction of porosity increases in the experimental alloys after solution heat treatment. As a result, the increase in the size of MC carbides and the porosity has a detrimental effect on the low temperature and high stress creep behavior of the alloys. The specimen crept at 850 °C and 586 MPa with the carbon content of 430 ppm shows the shortest rupture life due to the largest primary creep strain. However, the creep behavior of the alloy at 1120 °C and 140 MPa gets better as the carbon content increases from 88 to 430 ppm. TCP phase is observed near the fracture surfaces of the alloys, which explores as a potential cause for the creep rupture. However, the formation of TCP phase is effectively suppressed for decreasing segregation of the alloying elements, which results in the improvement of the creep life in the alloy with 430 ppm carbon at 1120 °C and 140 MPa.

Determining ice water content from 2D crystal images in convective cloud systems

Science.gov (United States)

Leroy, Delphine; Coutris, Pierre; Fontaine, Emmanuel; Schwarzenboeck, Alfons; Strapp, J. Walter

2016-04-01

Cloud microphysical in-situ instrumentation measures bulk parameters like total water content (TWC) and/or derives particle size distributions (PSD) (utilizing optical spectrometers and optical array probes (OAP)). The goal of this work is to introduce a comprehensive methodology to compute TWC from OAP measurements, based on the dataset collected during recent HAIC (High Altitude Ice Crystals)/HIWC (High Ice Water Content) field campaigns. Indeed, the HAIC/HIWC field campaigns in Darwin (2014) and Cayenne (2015) provide a unique opportunity to explore the complex relationship between cloud particle mass and size in ice crystal environments. Numerous mesoscale convective systems (MCSs) were sampled with the French Falcon 20 research aircraft at different temperature levels from -10°C up to 50°C. The aircraft instrumentation included an IKP-2 (isokinetic probe) to get reliable measurements of TWC and the optical array probes 2D-S and PIP recording images over the entire ice crystal size range. Based on the known principle relating crystal mass and size with a power law (m=α•Dβ), Fontaine et al. (2014) performed extended 3D crystal simulations and thereby demonstrated that it is possible to estimate the value of the exponent β from OAP data, by analyzing the surface-size relationship for the 2D images as a function of time. Leroy et al. (2015) proposed an extended version of this method that produces estimates of β from the analysis of both the surface-size and perimeter-size relationships. Knowing the value of β, α then is deduced from the simultaneous IKP-2 TWC measurements for the entire HAIC/HIWC dataset. The statistical analysis of α and β values for the HAIC/HIWC dataset firstly shows that α is closely linked to β and that this link changes with temperature. From these trends, a generalized parameterization for α is proposed. Finally, the comparison with the initial IKP-2 measurements demonstrates that the method is able to predict TWC values

Methodology for fast evaluation of Bacillus thuringiensis crystal protein content

Directory of Open Access Journals (Sweden)

Alves Lúcia M. Carareto

2000-01-01

Full Text Available The development of the production and use of Bacillus thuringiensis in Brazil at a commercial scale faces certain difficulties, among them the establishment of efficient methodologies for the quantitation of toxic products to be commercialized. Presently, the amount of toxin is given in percentage by analyzing the samples total protein content. Such methodology however, does not measure the actual amount of active protein present in the product, since most strains express different endotoxin genes and might even produce b-toxin. Since the various types of toxins exhibit different antigenic characteristics, this work has as objective the utilization of fast immunological techniques to quantify the level of crystal protein. Crystal protein produced by a subspecies of Bacillus thuringiensis var. israelensis was purified by ultracentrifugation and utilized to immunize rabbits and to produce hiperimmune sera. Such sera were latter used to evaluate the level of proteins on commercial bioinsecticide and on laboratory cultures of B. thuringiensis through the immunodot technique. The results were obtained by comparison of data obtained from reactions with known concentrations of crystal protein permitting to evaluate the level of such protein on various materials.

Influence of TiO2 content on the crystallization and microstructure of machinable glass-ceramics

Directory of Open Access Journals (Sweden)

Debasis Pradip Mukherjee

2016-03-01

Full Text Available Glasses based on the SiO2–Al2O3–MgO–K2O–B2O3–MgF2 system added with TiO2 were synthesized and characterized by differential scanning calorimetry (DSC, X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM techniques. The results showed that by increasing the TiO2 content, glass transition temperature (Tg, both the crystallization peak temperature (TpI and TpII and activation energy (E increased. The interconnected large blocky card-like crystals were identified as fluorophlogopite as a major crystalline phase for all three glass-ceramic specimens by (XRD and subsequently confirmed by SEM. The Vickers hardness (Hv value for glass-ceramic specimens decreases with progressively increasing TiO2 content (1–10 wt% and Titania containing MGT-3 glass-ceramic specimen with interconnected large blocky card-like fluorophlogopite mica crystals possess lower Hv (4.26 GPa as well as good machinability (m = 0.12 useable for machinable applications. The study shows that Titania promoted initial crystallization of glass and can be used as an effective nucleting agent.

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.

PA6 and Kevlar fiber reinforced isotactic polypropylene: Structure, mechanical properties and crystallization and melting behavior

International Nuclear Information System (INIS)

Zhao, Songfang; Cheng, Lei; Guo, Yong; Zheng, Yuying; Li, Baoming

2012-01-01

Highlights: ► KF was modified with caprolactam using toluenediisocyanate (TDI) as bridge. ► Modified KF improves interfacial interaction of iPP/KF/PA6 composites. ► Fiber and nylon 6 inhibited the crystallization of PP continuous phase. -- Abstract: To improve the thermal and mechanical properties of isotactic polypropylene (iPP), iPP/Kevlar fiber (KF)/polyamide 6 (PA6) composites were prepared via the melt-extrusion method on twin-screw extruder. Kevlar fiber was modified with caprolactam using toluenediisocyanate (TDI) as bridge. The microstructure of modified KF was successfully characterized by Fourier transform infrared (FT-IR), X-ray photoelectron spectrometer (XPS) and scanning electron microscopy (SEM), the results showed that KF was bonded with caprolactam and became coarser. Then the modified KF was introduced into iPP, the composites have better mechanical and thermal properties, implying that modification of KF was helpful to improve the interfacial interaction of iPP/KF/PA6 composites. Besides, the crystallization curves indicated that crystallization behavior of PA6 in the composites was homogeneous and fractional. Furthermore, compatibilizer content played an important role in the mechanical and thermal properties of composites.

Crystallization behavior of Ge-doped eutectic Sb70Te30 films in optical disks

International Nuclear Information System (INIS)

Khulbe, Pramod K.; Hurst, Terril; Mansuripur, Masud; Horie, Michikazu

2002-01-01

We report laser-induced crystallization behavior of binary Sb-Te and ternary Ge-doped eutectic Sb70Te30 thin film samples in a typical quadrilayer stack as used in phase-change optical disk data storage. Several experiments have been conducted on a two-laser static tester in which one laser operating in pulse mode writes crystalline marks on amorphous film or amorphous marks on crystalline film, while the second laser operating at low-power cw mode simultaneously monitors the progress of the crystalline or amorphous mark formation in real time in terms of the reflectivity variation. The results of this study show that the crystallization kinetics of this class of film is strongly growth dominant, which is significantly different from the crystallization kinetics of stochiometric Ge-Sb-Te compositions. In Sb-Te and Ge-doped eutectic Sb70Te30 thin-film samples, the crystallization behavior of the two forms of amorphous states, namely, as-deposited amorphous state and melt-quenched amorphous state, remains approximately same. We have also presented experiments showing the effect of the variation of the Sb/Te ratio and Ge doping on the crystallization behavior of these films

In-Line Measurement of Water Content in Ethanol Using a PVA-Coated Quartz Crystal Microbalance

Directory of Open Access Journals (Sweden)

Byoung Chul Kim

2014-01-01

Full Text Available An in-line device for measuring the water content in ethanol was developed using a polyvinyl alcohol (PVA-coated quartz crystal microbalance. Bio-ethanol is widely used as the replacement of gasoline, and its water content is a key component of its specifications. When the PVA-coated quartz crystal microbalance is contacted with ethanol containing a small amount of water, the water is absorbed into the PVA increasing the load on the microbalance surface to cause a frequency drop. The determination performance of the PVA-coated microbalance is examined by measuring the frequency decreases in ethanol containing 2% to 10% water while the ethanol flows through the measurement device. The measurements indicates that the higher water content is the more the frequency reduction is, though some deviation in the measurements is observed. This indicates that the frequency measurement of an unknown concentration of water in ethanol can be used to determine the water content in ethanol. The PVA coating is examined by microscopy and FTIR (Fourier transform infrared spectroscopy.

Frequency and Thermal Behavior of Acoustic Absorption in ɛ-GaSe Crystals

Science.gov (United States)

Dzhafarova, S. Z.

2018-04-01

The paper presents results of measuring acoustic absorption in ɛ-GaSe crystals. The absorption of a longitudinal wave which propagates normal to the crystal layers, quadratically depends on frequency. However, it does not depend on temperature, i.e. it displays an Akhiezer behavior although its absolute value considerably exceeds the expected. The analysis of the frequency and thermal behavior of absorption of piezoelectric waves propagating along the layers, includes the deduction of contribution made by the interaction between waves and charge carriers. This analysis shows the linear dependence between the lattice absorption of these waves and the frequency. The linear frequency and weak temperature dependences of the acoustic absorption characterize the additional ultra-Akhiezer absorption in glasses. In our case, it can be caused by various polytypes forming in GaSe crystals which differ merely in a mutual arrangement of layers.

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

The Effect of Chain Structures on the Crystallization Behavior and Membrane Formation of Poly(Vinylidene Fluoride Copolymers

Directory of Open Access Journals (Sweden)

Wenzhong Ma

2014-05-01

Full Text Available The crystallization behaviors of two copolymers of PVDF were studied, and the effect of copolymerized chains on the crystallization behavior was investigated. The results indicated that both copolymers had a lowered crystallization temperature and crystallinity. The crystallization rate was improved by the copolymer with symmetrical units in PVDF chains, but hindered by asymmetrical units, compared with the neat PVDF. The symmetrical units in PVDF chains favored the β-crystals with fiber-like structures. According to the solubility parameter rule, methyl salicylate (MS can be chosen as a diluent for PVDF copolymers. Both diluted systems had liquid-liquid (L-L regions in the phase diagrams, which was due to the lowered crystallization temperature.

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. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Non-isothermal crystallization of PET/PLA blends

International Nuclear Information System (INIS)

Chen, Huipeng; Pyda, Marek; Cebe, Peggy

2009-01-01

Binary blends of poly(ethylene terephthalate) with poly(lactic acid), PET/PLA, were studied by differential scanning calorimetry and X-ray scattering. The PET/PLA blends, prepared by solution casting, were found to be miscible in the melt over the entire composition range. Both quenched amorphous and semicrystalline blends exhibit a single, composition dependent glass transition temperature. We report the non-isothermal crystallization of (a) PET, with and without the presence of PLA crystals and (b) PLA, with and without the presence of PET crystals. PET can crystallize in all blends, regardless of whether PLA is amorphous or crystalline, and degree of crystallinity of PET decreases as PLA content increases. In contrast, PLA crystallization is strongly affected by the mobility of the PET fraction. When PET is wholly amorphous, PLA can crystallize even in 70/30 blends, albeit weakly. But when PET is crystalline, PLA cannot crystallize when its own content drops below 0.90. These different behaviors may possibly be related to the tendency of each polymer to form constrained chains, i.e., to form the rigid amorphous fraction, or RAF. PET is capable of forming a large amount of RAF, whereas relatively smaller amount of RAF forms in PLA. Like the crystals, the rigid amorphous fraction of one polymer component may inhibit the growth of crystals of the other blend partner.

Influence of clay content on the melting behavior and crystal structure of nonisothermal crystallized poly(L-lactic acid)/nanocomposites

Czech Academy of Sciences Publication Activity Database

Ublekov, F.; Baldrian, Josef; Kratochvíl, Jaroslav; Steinhart, M.; Nedkov, E.

2012-01-01

Roč. 124, č. 2 (2012), s. 1643-1648 ISSN 0021-8995 Institutional research plan: CEZ:AV0Z40500505 Keywords : biopolymers * nanocomposite s * crystal structures Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.395, year: 2012

Effect of Y addition on crystallization behavior and soft-magnetic properties of Fe{sub 78}Si{sub 9}B{sub 13} ribbons

Energy Technology Data Exchange (ETDEWEB)

Zhanwei, Liu; Dunbo, Yu, E-mail: yudb2008@126.com; Kuoshe, Li; Yang, Luo; Chao, Yuan; Zilong, Wang; Liang, Sun; Kuo, Men

2017-08-15

Highlights: • Thermal stability of Fe-Si-B amorphous alloy is enhanced by Y addition. • Y addition can improve soft magnetic properties of Fe-Si-B amorphous alloy. • Decomposition of metastable Fe{sub 3}B phase is related to Y content in Fe-Si-B matrix. - Abstract: A series of amorphous Fe-Si-B ribbons with various Y addition were prepared by melt-spinning. The effect of Y addition on crystallization behavior, thermal and magnetic properties was systematically investigated. With the increase of Y content, the initial crystallization temperature shifted to a higher temperature, indicating that the thermal stability of amorphous state in Fe-Si-B-Y ribbon is enhanced compared to that of Fe-Si-B alloy. Meanwhile, compared to the two exothermic peaks in the samples with lower Y content, a new exothermic peak was found in the ribbons with Y content higher than 1 at%, which corresponded to the decomposition of metastable Fe{sub 3}B phase. Among all the alloys, Fe{sub 76.5}Si{sub 9}B{sub 13}Y{sub 1.5} alloy exhibits optimized magnetic properties, with high saturation magnetization M{sub s} of 187 emu/g and low coercivity H{sub cJ} of 7.6 A/m.

Crystal growth and magneto-transport behavior of PdS1-δ

Science.gov (United States)

Cao, Lin; Lv, Yang-Yang; Chen, Si-Si; Li, Xiao; Zhou, Jian; Yao, Shu-Hua; Chen, Y. B.; Lu, Minghui; Chen, Yan-Feng

2018-04-01

PdS is theoretically proposed to novel topological material with eight-band fermions. Here, PdS1-δ crystals were successfully grown from KI as solvent by modified flux method. The single crystalline quality and compositional homogeneity of grown PdS1-δ are characterized by X-ray diffraction and energy dispersion spectroscopy. Temperature dependent electrical transport property of PdS1-δ demonstrates a semiconductor-like behavior. Analysis of temperature-dependent resistance indicates that there is variable-range-hopping behavior at low temperature. The clear negative MR of PdS1-δ single crystals is measured at the low temperature (interaction between conducting carriers and localized moments. however, the magneto-transport results have not shown the clues of topological feature of PdS.

Effect of copper valence on the glass structure and crystallization behavior of Bi-Pb-Cu-O glasses

International Nuclear Information System (INIS)

Hu, Yi; Lin, U.-L.; Liu, N.-H.

1997-01-01

Bi 0.43 Pb 0.35 Cu 0.22 O y glasses with different Cu + contents were prepared by melting at different temperatures. The glass structure consists of [BiO 3 [ and [BiO 6 [ units and the ratio of [BiO 3 [/[BiO 6 [ increases with increasing Cu + content. The glass transition temperature, the first crystallization temperature peak, and the thermal stability of the glasses decreases with increasing Cu + content. The value of the activation energy, E a , varies as a function of the Cu + content. The crystallization mechanism in the glasses is closely related to the glass structure, which is mainly affected by the Cu + content. (orig.)

Crystallization behavior of Zr62Al8Ni13Cu17 Metallic Glass

Directory of Open Access Journals (Sweden)

Jo Mi Sun

2017-06-01

Full Text Available The crystallization behavior has been studied in Zr62Al8Ni13Cu17 metallic glass alloy. The Zr62Al8Ni13Cu17 metallic glass crystallized through two steps. The fcc Zr2Ni phase transformed from the amorphous matrix during first crystallization and then the Zr2Ni and residual amorphous matrix transformed into a mixture of tetragonal Zr2Cu and hexagonal Zr6Al2Ni phases. Johnson-Mehl-Avrami analysis of isothermal transformation data suggested that the formation of crystalline phase is primary crystallization by diffusion-controlled growth.

Crystallization and degradation behaviors of poly(butylene succinate)/poly(Z-L-lysine) composites

International Nuclear Information System (INIS)

Tan, Licheng; Hu, Jun; Ye, Suwen; Wei, Junchao; Chen, Yiwang

2014-01-01

Highlights: • A new biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were successfully prepared through physical blend. • PZlys may greatly affected the crystallization behaviors of PBS without changing its crystalline structure. • The degradation speed of PBS may be greatly accelerated by introduction of PZlys in PBS matrix. - Abstract: A new type of biodegradable poly(butylene succinate) (PBS)/poly(Z-L-lysine) (PZlys) composites were prepared. The crystallization behaviors were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM) and the results showed that PZlys can restrict the crystallization of PBS, the crystallization speed of PBS/PZlys were slower than that of PBS, and the crystallization degree of the composites were smaller than that of PBS. However, the WAXD results showed that the incorporation of PZlys did not change the crystalline structure of PBS. The in vitro degradation experiments demonstrated that the degradation speed of the composites were faster than that of PBS. Moreover, the mechanical properties of the composites showed that the composites with a proper composition (for example, 80/20) can keep the mechanical properties of PBS without evident difference, which implied that the composites might be potentially useful as biodegradable materials

Anisotropic surface chemistry properties and adsorption behavior of silicate mineral crystals.

Science.gov (United States)

Xu, Longhua; Tian, Jia; Wu, Houqin; Fang, Shuai; Lu, Zhongyuan; Ma, Caifeng; Sun, Wei; Hu, Yuehua

2018-03-07

Anisotropic surface properties of minerals play an important role in a variety of fields. With a focus on the two most intensively investigated silicate minerals (i.e., phyllosilicate minerals and pegmatite aluminosilicate minerals), this review highlights the research on their anisotropic surface properties based on their crystal structures. Four surface features comprise the anisotropic surface chemistry of minerals: broken bonds, energy, wettability, and charge. Analysis of surface broken bond and energy anisotropy helps to explain the cleavage and growth properties of mineral crystals, and understanding surface wettability and charge anisotropy is critical to the analysis of minerals' solution behavior, such as their flotation performance and rheological properties. In a specific reaction, the anisotropic surface properties of minerals are reflected in the adsorption strengths of reagents on different mineral surfaces. Combined with the knowledge of mineral crushing and grinding, a thorough understanding of the anisotropic surface chemistry properties and the anisotropic adsorption behavior of minerals will lead to the development of effective relational models comprising their crystal structure, surface chemistry properties, and targeted reagent adsorption. Overall, such a comprehensive approach is expected to firmly establish the connection between selective cleavage of mineral crystals for desired surfaces and designing novel reagents selectively adsorbed on the mineral surfaces. As tools to characterize the anisotropic surface chemistry properties of minerals, DLVO theory, atomic force microscopy (AFM), and molecular dynamics (MD) simulations are also reviewed. Copyright © 2017 Elsevier B.V. All rights reserved.

Crystallization behavior and controlling mechanism of iron-containing Si-C-N ceramics.

Science.gov (United States)

Francis, Adel; Ionescu, Emanuel; Fasel, Claudia; Riedel, Ralf

2009-11-02

The crystallization behavior and controlling mechanism of the Si-Fe-C-N system based on polymer-derived SiCN ceramic filled with iron metal powder has been studied. The composite preparation conditions allow the formation of a random distribution of metallic particles in the polymer matrix volume for the Si-C-N system. Pyrolysis of the composite material at 1100 degrees C indicates the presence of one crystalline phase Fe(3)Si. While the sample pyrolyzed at 1200 degrees C reveals the formation of both Fe(3)Si and Fe(5)Si(3) phases, a crystallization of beta-SiC is additionally observed by increasing the temperature up to 1300 degrees C. The propensity for the formation of SiC is due to the presence of Fe(5)Si(3), where a solid-liquid-solid (SLS) growth mechanism was suggested to occur. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermal gravimetric analysis with mass spectroscopic detection (TGA-MS) were employed to investigate the crystallization behavior of the Si-Fe-C-N system.

Crystallization Behavior of A Bulk Amorphous Mg62Cu26Y12 Alloy

Science.gov (United States)

Wu, Shyue-Sheng; Chin, Tsung-Shune; Su, Kuo-Chang

1994-07-01

The crystallization temperature, the associated activation energy and the crystallized structure of a bulk amorphous Mg62Cu26Y12 alloy with a diameter of 2.5 mm were studied. It possesses a one-step crystallization behavior. The crystallization reaction was found to be represented by: AM(MG62Cu26Y12)→Mg2Cu+MgY+CuY+Mg, ( Tx=188°C, Eac=134 kJ/mol) where AM represents the amorphous state, T x the crystallization temperature at an infinitesimal heating rate, and E ac the associated activation energy. The amount of crystalline phases were found to be Mg2Cu:MgY:CuY=76:17:7. The Mg phase is identifiable only by high resolution electron microscopy, not by X-ray diffraction. The crystallization leads to a sharp rise in electrical resistivity which is reversed to those of iron-based amorphous alloys.

Preparation of Lead Magnesium Niobate-Lead Zirconate Titanate Films and Their Crystallization Behaviors

International Nuclear Information System (INIS)

Tursiloadi, Silvester

2002-01-01

The thin films with composition near morpotropic phase boundary (MPB) of the system xPb(Mg 1 /3, Nb 2 /3) O 3 -yPbTiO 3 -zPbZrO 3 (x = 0-0.35, y = 0.47 and z = 0.53), were prepared by sol-gel method. The starting materials were consisted of Pb(iso-OC 3 H 7 ) 2 , Zr(n-OC 4 H 9 ) 4 , Ti(iso-OC 3 H 7 ) 4 , Mg(CH 3 COO) 2 4H 2 O and Nb(OC 2 H 5 ) 5 . The l-propanol was used as solvent. The concentration of PMN-PT-PZ in coating solution was 0.7 M, and the pH of the solution was 4.5. The thin films were prepared by dip coating and spin coating. The crystallization behaviors of the PMN-PT-PZ thin films showed that the formation of perovskite phase at low temperature becomes difficult with increasing the content of PMN. The amounts of pyrochlore and perovskite phase in PMN-PT-PZ films depended on the heating temperatures, and PMN contents. Single-phase perovskite was found for the coated films containing 0 and 12.5 mol% after calculating at 600 o C, 21 mol% after calculating at 700 o C, and 30 mol% after calculating at 750 o C. Single-phase perovskite of coated films will never be found when the content of PMN was 35 mol%

Random crystal field effect on the magnetic and hysteresis behaviors of a spin-1 cylindrical nanowire

Energy Technology Data Exchange (ETDEWEB)

Zaim, N.; Zaim, A., E-mail: ah_zaim@yahoo.fr; Kerouad, M., E-mail: kerouad@fs-umi.ac.ma

2017-02-15

In this work, the magnetic behavior of the cylindrical nanowire, consisting of a ferromagnetic core of spin-1 atoms surrounded by a ferromagnetic shell of spin-1 atoms is studied in the presence of a random crystal field interaction. Based on Metropolis algorithm, the Monte Carlo simulation has been used to investigate the effects of the concentration of the random crystal field p, the crystal field D and the shell exchange interaction J{sub s} on the phase diagrams and the hysteresis behavior of the system. Some characteristic behaviors have been found, such as the first and second-order phase transitions joined by tricritical point for appropriate values of the system parameters, triple and isolated critical points can be also found. Depending on the Hamiltonian parameters, single, double and para hysteresis regions are explicitly determined. - Highlights: • Phase diagrams of a ferromagnetic nanowire are examined by the Monte Carlo simulation. • Different types of the phase diagrams are obtained. • The effect of the random crystal field on the hysteresis loops is studied. • Single, double and para hysteresis regions are explicitly determined.

Diffusion in a pure, high-vacancy-content crystal

International Nuclear Information System (INIS)

McKee, R.A.

1981-01-01

The idea that vacancies can follow a nonrandom walk in a solid has been developed and put into a quantitative form for diffusion in a pure, high-vacancy-content crystal. Intrinsic and tracer diffusion in a metal have been analyzed, and the electrical mobility in an ionic solid has been expressed in terms of the tracer diffusion coefficient and the separate correlation factors for atoms and vacancies. The description uses classical methods of diffusion theory, and generalized results that account for nonrandom vacancy walk have been shown to reduce to those obtained by Howard and Lidiard in a system where the vacancy moves randomly as an isolated point defect. Experimental data for carbon diffusion in fcc iron have been examined to illustrate an interstitial-vacancy analogy that was used in this analysis, and the general result has been applied specifically to discuss vacancy diffusion in Fe/sub 1-x/S

Tricritical behavior in the diluted transverse spin-1 Ising model with a longitudinal crystal field

International Nuclear Information System (INIS)

Htoutou, K.; Oubelkacem, A.; Ainane, A.; Saber, M.

2005-01-01

The transverse spin-1 Ising model with a longitudinal crystal field exhibits a tricritical behavior. Within the effective field theory with a probability distribution technique that accounts for the self-spin correlations, we have studied the influence of site dilution on this behavior and have calculated the temperature-transverse field-longitudinal crystal field-concentration phase diagrams and determined, in particular, the influence of the concentration of magnetic atoms c on the tricritical behavior. We have found that the tricritical point appears for large values of the concentration c of magnetic atoms and disappears with the increase in dilution (small values of c). Results for square lattice are calculated numerically and some interesting results are obtained. In certain ranges of values of the strength of the longitudinal crystal field D/J when it becomes sufficiently negative, we found re-entrant phenomenon, which disappears with increase in the value of the strength of the transverse field

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...... revealed that the applied melt pre-shear within the experimental range could enhance the nucleation of crystal II and accelerate the diameter growth of the formed spherulites. If the applied melt pre-shear rate was large enough, Shish-Kebabs structure could be formed. After the isothermal crystallization...... was formed in the melt pre-sheared iP-1-B samples. Further investigations were applied with synchrotron radiation instruments. Wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) after the crystal transition showed that the applied melt pre-shear could result in orientated fine...

Crystallization behavior of (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses

Energy Technology Data Exchange (ETDEWEB)

Wang, Moo-Chin [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Cheng, Chih-Wei; Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Hsi, Chi-Shiung, E-mail: chsi@nuu.edu.t [Department of Materials Science and Engineering, National United University, 1 Lien-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China)

2010-07-02

The crystallization behavior of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and energy dispersive spectroscopy (EDS). The crystalline phase was composed of {beta}-spodumene. The isothermal crystallization kinetics of {beta}-spodumene from the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has also been studied by a quantitative X-ray diffraction method. The activation energy of {beta}-spodumene formation decreases from 359.2 to 317.8 kJ/mol when the Na{sub 2}O content increases from 0 to 0.4 mol and it increases from 317.8 to 376.9 kJ/mol when the Na{sub 2}O content increases from 0.4 to 0.6 mol. The surface nucleation and plate-like growth were dominant in the crystallization of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses.

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

2013-11-21

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.

Crystallization and melting behavior of nanoclay-containing polypropylene/poly(trimethylene terephthalate blends

Directory of Open Access Journals (Sweden)

S. H. Jafari

2012-02-01

Full Text Available This contribution concerns preparation and characterization of polypropylene (PP/poly(trimethylene terephthalate (PTT melt-mixed blends in the presence of organically-modified montmorillonite nanoclays and functional compatibilizers. Immiscibility and nanocomposite formation were confirmed via transmission electron microscopy. An intercalated structure was observed by wide angle X-ray diffraction technique. Crystallization, and melting characteristics were studied by differential scanning calorimetry in both isothermal and non-isothermal modes, supplemented by temperature modulated DSC (TMDSC. A concurrent crystallization was found for both polymeric components in the blends. Whereas blending favored PP crystallizability, it interrupted that of PTT. The addition compatibilizers interfered with rate, temperature, and degree of crystallization of PP and PTT. On the contrary, nanoclays incorporation increased crystallizability of each individual component. However, as for blend nanocomposite samples, the way the crystallization behavior changed was established to depend on the type of nanoclay. Based on kinetic analysis, isothermal crystallization nucleation followed athermal mechanism, while that of non-isothermal obeyed thermal mode. Addition of nanoclays shifted nucleation mechanism from athermal to thermal mode.

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

KAUST Repository

Kelarakis, Antonios; Giannelis, Emmanuel P.

2011-01-01

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

In-Line Measurement of Water Contents in Ethanol Using a Zeolite-Coated Quartz Crystal Microbalance

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Byoung Chul Kim

2015-10-01

Full Text Available A quartz crystal microbalance (QCM was utilized to measure the water content in ethanol. For the improvement of measurement sensitivity, the QCM was modified by applying zeolite particles on the surface with poly(methyl methacrylate (PMMA binder. The measurement performance was examined with ethanol of 1% to 5% water content in circulation. The experimental results showed that the frequency drop of the QCM was related with the water content though there was some deviation. The sensitivity of the zeolite-coated QCM was sufficient to be implemented in water content determination, and a higher ratio of silicon to aluminum in the molecular structure of the zeolite gave better performance. The coated surface was inspected by microscopy to show the distribution of zeolite particles and PMMA spread.

Dielectric behavior and phase transition in [111]-oriented PIN–PMN–PT single crystals under dc bias

Directory of Open Access Journals (Sweden)

Yuhui Wan

2014-01-01

Full Text Available Temperature and electric field dependences of the dielectric behavior and phase transition for [111]-oriented 0.23PIN–0.52PMN–0.25PT (PIN-PMN–0.25PT and 0.24PIN–0.43PMN–0.33PT (PIN–PMN–0.33PT single crystals were investigated over a temperature range from -100°C to 250°C using field-heating (FH dielectric measurements. The transition phenomenon from ferroelectric microdomain to macrodomain was found in rhombohedra (R phase region in the single crystals under dc bias. This transition temperature Tf of micro-to-macrodomain is sensitive to dc bias and move quickly to lower temperature with increasing dc bias. The phase transition temperatures in the two single crystals shift toward high temperature and the dielectric permittivities at the phase transition temperature decrease with increasing dc bias. Especially, the phase transition peaks are gradually broad in PIN–PMN–0.33PT single crystal with the increasing dc bias. Effects of dc bias on the dielectric behavior and phase transition in PIN–PMN–PT single crystals are discussed.

Crystallization and deuterium permeation behaviors of yttrium oxide coating prepared by metal organic decomposition

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Takumi Chikada

2016-12-01

Full Text Available Yttrium oxide coatings were fabricated on reduced activation ferritic/martensitic steels by metal organic decomposition with a dip-coating technique, and their deuterium permeation behaviors were investigated. The microstructure of the coatings varied with heat-treatment temperature: amorphous at 670ºC (amorphous coating and crystallized at 700ºC (crystallized coating. Deuterium permeation flux of the amorphous coating was lower than the uncoated steel by a factor of 5 at 500ºC, while that of the crystallized coating was lower by a factor of around 100 at 400‒550ºC. The permeation fluxes of both coatings were drastically decreased during the measurements at higher temperatures by a factor of up to 790 for the amorphous coating and 1000 for the crystallized one, indicating a microstructure modification occurred by an effect of test temperature with hydrogen flux. Temperature dependence of deuterium diffusivity in the coatings suggests that the decrease of the permeation flux has been derived from a decrease of the diffusivity. Characteristic permeation behaviors were observed with different annealing conditions; however, they can be interpreted using the permeation mechanism clarified in the previous erbium oxide coating studies.

Effects of Poly(cyclohexanedimethylene terephthalate on Microstructures, Crystallization Behavior and Properties of the Poly(ester ether Elastomers

Directory of Open Access Journals (Sweden)

Yi-Cheng Feng

2017-06-01

Full Text Available To understand the role of molecular structure on the crystallization behavior of copolyester in thermoplastic poly(ether ester elastomers (TPEEs, series of poly(butylene-co-1,4-cyclohexanedimethylene terephthalate (P(BT-co-CT-b-poly(tetramethylene glycol (PTMG are synthesized through molten polycondensation process. The effects of poly(cyclohexanedimethylene terephthalate (PCT content on the copolymer are investigated by Fourier transform infrared spectroscopy (FT-IR, 1H and 13C nuclear magnetic resonance (NMR, gel permeation chromatographs (GPC, wide-angle X-ray diffraction (WAXD, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, mechanical, and visible light transmittance tests. FT-IR and NMR results confirm the incorporation of PCT onto the copolymer. WAXD and DSC indicate that the crystalline structure of the copolymers changed from α-PBT lattice to trans-PCT lattice when the molar fraction of PCT (MPCT is above 30%, while both crystallization and melting temperatures reach the minima. An increase in MPCT led to an increase in the number sequence length of PCT, the thermal stability and the visible light transmittance of the copolymer, but to a slight decrease in tensile strength and elastic modulus.

Mining social media: tracking content and predicting behavior

NARCIS (Netherlands)

Tsagkias, M.

2012-01-01

The advent of social media has established a symbiotic relationship between social media and online news. This relationship can be leveraged for tracking news content, and predicting behavior with tangible real-world applications, e.g., online reputation management, ad pricing, news ranking, and

Sexty Southerners: Sexting Content and Behaviors among Selected Southern Undergraduates

Science.gov (United States)

Hudson, Heather K.; Marshall, S. Alexandra

2016-01-01

Sexting is defined as sending/posting/sharing sexually explicit messages or nude/semi-nude images via electronic communication. Purpose: The purpose of this study was to assess and determine relationships of sexting behavioral intentions, sexting behaviors, and sexting content among selected Southern undergraduate students. Methods: Survey…

Shape effect related to crystallographic orientation of deformation behavior in copper crystals

International Nuclear Information System (INIS)

Kim, K.H.; Chang, C.H.; Koo, Y.M.; MacDowell, A.A.

1999-01-01

The deformation behavior of pure copper single crystals has been investigated by scanning electron microscopy and synchrotron radiation using the in situ reflection Laue method. Two types of samples with the same orientation of tensile axes, but with different crystallographic orientations in the directions of the width and thickness of the samples, have been studied. They showed different characteristics of deformation behavior, such as the activated slip systems, the movement of the tensile axis, and the mode of fracture

Information Seeking in Social Media: A Review of YouTube for Sedentary Behavior Content.

Science.gov (United States)

Knight, Emily; Intzandt, Brittany; MacDougall, Alicia; Saunders, Travis J

2015-01-20

The global prevalence of sedentary lifestyles is of grave concern for public health around the world. Moreover, the health risk of sedentary behaviors is of growing interest for researchers, clinicians, and the general public as evidence demonstrates that prolonged amounts of sedentary time increases risk for lifestyle-related diseases. There is a growing trend in the literature that reports how social media can facilitate knowledge sharing and collaboration. Social sites like YouTube facilitate the sharing of media content between users. The purpose of this project was to identify sedentary behavior content on YouTube and describe features of this content that may impact the effectiveness of YouTube for knowledge translation. YouTube was searched on a single day by 3 independent reviewers for evidence-based sedentary behavior content. Subjective data (eg, video purpose, source, and activity type portrayed) and objective data (eg, number of views, comments, shares, and length of the video) were collected from video. In total, 106 videos met inclusion criteria. Videos were uploaded from 13 countries around the globe (ie, Australia, Barbados, Belgium, Canada, Colombia, Kenya, New Zealand, Russia, South Africa, Spain, Ukraine, United Kingdom, United States). The median video length was 3:00 minutes: interquartile range (IQR) 1:44-5:40. On average, videos had been on YouTube for 15.0 months (IQR 6.0-27.5) and had been viewed 239.0 times (IQR 44.5-917.5). Videos had remarkably low numbers of shares (median 0) and comments (median 1). Only 37.7% (40/106) of videos portrayed content on sedentary behaviors, while the remaining 66 videos portrayed physical activity or a mix of behaviors. Academic/health organizations (39.6%, 42/106) and individuals (38.7%, 41/106) were the most prevalent source of videos, and most videos (67.0%, 71/106) aimed to educate viewers about the topic. This study explored sedentary behavior content available on YouTube. Findings demonstrate that

Crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders synthesized by a coprecipitation process

Energy Technology Data Exchange (ETDEWEB)

Chu, Hsueh-Liang [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Hwang, Weng-Sing [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Institute of Nanotechnology and Microsystems Engineering, National Cheng Kung University, 1 Ta- Hsueh Road, Tainan 70101, Taiwan (China); Du, Je-Kang [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); Chen, Ker-Kong, E-mail: enamel@kmu.edu.tw [Department of Dentistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Department of Dentistry, Kaohsiung Medical University, Chung Ho Memorial Hospital, 100 Tzyou 1st Road, Kaohsiung 80708, Taiwan (China); 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)

2016-09-05

Crystallization behaviors of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders were studied with zirconium nitrate (Zr(NO{sub 3}){sub 4}·xH{sub 2}O), yttrium nitrate (Y(NO{sub 3}){sub 3}·6H{sub 2}O) and strontium nitrate (Sr(NO{sub 3}){sub 2}) constituting the initial materials. Differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED) and high-resolution TEM (HRTEM) were utilized to characterize the crystallization behavior of ZrO{sub 2}−3Y{sub 2}O{sub 3}−xSrO precursor powders. The activation energies of tetragonal ZrO{sub 2} (t-ZrO{sub 2}) crystallization were 389.1, 327.6, and 315.1 kJ/mol with SrO content for 1, 2, and 3 mol%, respectively, obtained with a non-isothermal method. The growth morphology parameter and growth mechanism index were close to 2.0 and 1.0, respectively, showing that t-ZrO{sub 2} had a plate-like morphology. - Highlights: • The single phase of tetragonal ZrO{sub 2} formed when calcined at 923 K for 2 h. • ZrO{sub 2}−3Y{sub 2}O{sub 3}−2SrO precursor powders crystallization is at 765.6 K. • The activation energy of t-ZrO{sub 2} crystallization was 389.1 kJ/mol with 1 mol% SrO. • The growth morphology and index of crystallization were close to 2.0 and 1.0.

On asymptotic isotropy for a hydrodynamic model of liquid crystals

Czech Academy of Sciences Publication Activity Database

Dai, M.; Feireisl, Eduard; Rocca, E.; Schimperna, G.; Schonbek, M.E.

2016-01-01

Roč. 97, 3-4 (2016), s. 189-210 ISSN 0921-7134 Grant - others:European Research Council(XE) MATHEF(320078) Institutional support: RVO:67985840 Keywords : liquid crystal * Q-tensor description * long-time behavior Subject RIV: BA - General Mathematics Impact factor: 0.933, year: 2016 http://content.iospress.com/articles/asymptotic-analysis/asy1348

On asymptotic isotropy for a hydrodynamic model of liquid crystals

Czech Academy of Sciences Publication Activity Database

Dai, M.; Feireisl, Eduard; Rocca, E.; Schimperna, G.; Schonbek, M.E.

2016-01-01

Roč. 97, 3-4 (2016), s. 189-210 ISSN 0921-7134 Grant - others:European Research Council(XE) MATHEF(320078) Institutional support: RVO:67985840 Keywords : liquid crystal * Q-tensor description * long-time behavior Subject RIV: BA - General Mathematics Impact factor: 0.933, year: 2016 http://content.iospress.com/articles/asymptotic- analysis /asy1348

Positive effects of television content on emotional and social behavior of children

Directory of Open Access Journals (Sweden)

Popović-Ćitić Branislava

2012-01-01

Full Text Available For decades, the dominance of studies with various aspects of the negative impact of television content as their subject of interest is evident in the field of theoretical and empirical analysis of the impact of television content on the development of children and youth, while the consideration of positive impact was mostly beyond the systematic interest of scientists and researchers. Even though the general assessment is that viewing prosocial television content may result in positive changes in social and emotional behavior of young people, research studies committed to the positive effects of television content on emotional and social behavior of children are scarce and insufficiently perceive the character and nature of the impact of television on the development of emotions and prosocial behavior during childhood. Based on the critical review of the findings of a number of foreign empirical studies, this article summarizes the research evidence of the positive effects of television content on emotional empathy, altruism, learning about emotions, social interaction and acceptance of diversity, with presentation of conclusions about potential mediator factors that may interact with the influences of television portrayals.

Glass transition behavior and crystallization kinetics of Cu0.3(SSe20)0.7 chalcogenide glass

International Nuclear Information System (INIS)

Soliman, A.A.

2005-01-01

The glass transition behavior and crystallization kinetics of Cu 0.3 (SSe 20 ) 0.7 chalcogenide glass were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD). Two crystalline phases (SSe 20 and Cu 2 Se) were identified after annealing the glass at 773 K for 24 h. The activation energy of the glass transition (E g ), the activation energy of crystallization (E c ), the Avrami exponent (n) and the dimensionality of growth (m) were determined. Results indicate that this glass crystallizes by a two-stage bulk crystallization process upon heating. The first transformation, in which SSe 20 precipitates from the amorphous matrix with a three-dimensional crystal growth. The second transformation, in which the residual amorphous phase transforms into Cu 2 Se compound with a two-dimensional crystal growth

The effect of UV exposure and heat treatment on crystallization behavior of photosensitive glasses

Science.gov (United States)

Kıbrıslı, Orhan; Ersundu, Ali Erçin

2018-05-01

In this study, photosensitive glasses in the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, silver, tin, antimony) and halogenides (NaF and KBr) were synthesized through a conventional melt-quenching technique. The crystallization mechanism was investigated for solely heat-treated and UV-exposed + heat-treated samples using differential thermal analysis (DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques to understand the effect of UV exposure on crystallization behavior of photosensitive glasses. Accordingly, non-isothermal DTA measurements were performed at different heating rates to determine crystallization peak, T p, and onset, T c, temperatures. For solely heat-treated samples, the kinetic parameters such as the Avrami constant, n, and morphology index, m, were calculated as 1 from the Ozawa method indicating surface crystallization and the value of crystallization activation energy was calculated as 944 kJ/mol using modified Kissinger method. On the contrary, bulk crystallization was found to be predominant for UV exposed + heat-treated samples revealing that UV exposure is the primary cause of bulk crystallization in photosensitive glasses.

Behavior of water of crystallization in CuSO4·5H2O studied by the tritium tracer method

International Nuclear Information System (INIS)

Sato, Tetsuya; Jiao, Yurong; Imaizumi, Hiroshi; Kano, Naoki

2011-01-01

Tritium (T) is one of hydrogen isotopes, and its chemical behavior is similar to other hydrogen isotopes. Therefore tritium is used as one of tracers in chemical experimental tracer. As one of applications, we tried to apply this method to clarifying the behavior of water of crystallization in an inorganic material. The sample used was copper sulfate pentahydrate. First, this compound was tritiated, then desorbed the water of crystallization from the tritiated compound. Comparing the behavior of amount of substance with the specific activity, the following four matters have been found. (1) There is no relation between each T concentration of HTO water and the mass of the compound within the T concentration used. (2) It can be confirmed that copper sulfate pentahydrate has three kinds of energetically different water of crystallization by T tracer method. (3) Each T concentration of water of crystallization is different at the coordinate position, and the HTO molecule is hard to coordinate at the position having weak binding force. (4) The T tracer method is useful to analyze the behavior of the combined water in materials. (author)

K-Basins particulate water content, and behavior

International Nuclear Information System (INIS)

DUNCAN, D.R.

1999-01-01

This analysis summarizes the state of knowledge of K-basins spent nuclear fuel oxide (film, particulate or sludge) and its chemically bound water in order to estimate the associated multi-canister overpack (MCO) water inventory and to describe particulate dehydration behavior. This information can be used to evaluate the thermal and chemical history of an MCO and its contents during cold vacuum drying (CVD), shipping, and interim storage

K-Basins particulate water content, and behavior

Energy Technology Data Exchange (ETDEWEB)

DUNCAN, D.R.

1999-02-25

This analysis summarizes the state of knowledge of K-basins spent nuclear fuel oxide (film, particulate or sludge) and its chemically bound water in order to estimate the associated multi-canister overpack (MCO) water inventory and to describe particulate dehydration behavior. This information can be used to evaluate the thermal and chemical history of an MCO and its contents during cold vacuum drying (CVD), shipping, and interim storage.

Mechanical Behavior and Fracture Properties of NiAl Intermetallic Alloy with Different Copper Contents

Directory of Open Access Journals (Sweden)

Tao-Hsing Chen

2016-03-01

Full Text Available The deformation behavior and fracture characteristics of NiAl intermetallic alloy containing 5~7 at% Cu are investigated at room temperature under strain rates ranging from 1 × 10−3 to 5 × 103 s−1. It is shown that the copper contents and strain rate both have a significant effect on the mechanical behavior of the NiAl alloy. Specifically, the flow stress increases with an increasing copper content and strain rate. Moreover, the ductility also improves as the copper content increases. The change in the mechanical response and fracture behavior of the NiAl alloy given a higher copper content is thought to be the result of the precipitation of β-phase (Ni,CuAl and γ'-phase (Ni,Cu3Al in the NiAl matrix.

Solidification behaviors of a single-crystal superalloy under lateral constraints

International Nuclear Information System (INIS)

Zhuangqi Hu; Huaming Wang

1993-01-01

The effect of lateral constraints ahead of solidification interface on the solidification behaviors of a newly developed hot corrosion resistant single-crystal nickel-base superalloy was investigated under commercial single-crystal production conditions. The lateral constraints or section variations ahead of solidification front were found to have drastic influences both on the modes of solidification and the profiles of solute segregation. As lateral constraints were imposed ahead of the directionally solidifying interface, the solidification microstructure of the single-crystal superalloy changed suddenly, through a γ/γ' eutectic-free zone which is characterized by an extremely-fine and highly-developed dendrite network, from the original well-branched dendritic structure to a fine cellular-dendrite or regular cell structure, accompanying which the primary arm spacing, the severity of segregation and the amount of microporosity decreased remarkably. The newly formed cellular dendrite or cell structure transforms always gradually to the initial coarse dendrite structure as the lateral constraint is finally released whether gradually or sharply. Moreover, an abnormal porosity zone was readily observed in the initial section beneath and away from the eutectic-free zone. The solidification microstructural changes were attributed to the drastic dynamical changes in local solidification cooling conditions and in momentum transport during solidification due to the presence of lateral constraint

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

International Nuclear Information System (INIS)

Huang, J.-W.; Wen, Y.-L.; Kang, C.-C.; Yeh, M.-Y.; Wen, S.-B.

2007-01-01

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 mI and T 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 g of Hoffman-Lauritzen theory were also determined by Vyazovkin's methods to support the interpretation

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.

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.

The creep deformation behavior of a single-crystal Co–Al–W-base superalloy at 900 °C

International Nuclear Information System (INIS)

Shi, L.; Yu, J.J.; Cui, C.Y.; Sun, X.F.

2015-01-01

The creep deformation behavior of a single-crystal Co–Al–W–Ni–Cr–Ta alloy with low tungsten content has been studied at stresses between 275 and 310 MPa at 900 °C. The alloy exhibits comparable creep strength with that of Co–Al–W-base alloys containing more tungsten. The creep deformation consists of three stages, the primary stage, the steady-state stage and the tertiary stage, when described by the creep strain rate versus time curve. At 900 °C, γ′ precipitates tend to raft along the direction of applied tensile stress in the steady-state creep stage and a topologically inverted and rafting γ/γ′ microstructure is formed in the tertiary stage. The main deformation mechanism in the primary creep stage is dislocation shearing of γ′ precipitates, and in the following creep stages, the dominant deformation mechanism is dislocations bypassing γ′ precipitates

Influence of carbon content on the copper-telluride phase formation and on the resistive switching behavior of carbon alloyed Cu-Te conductive bridge random access memory cells

International Nuclear Information System (INIS)

Devulder, Wouter; De Schutter, Bob; Detavernier, Christophe; Opsomer, Karl; Franquet, Alexis; Meersschaut, Johan; Muller, Robert; Van Elshocht, Sven; Jurczak, Malgorzata; Goux, Ludovic; Belmonte, Attilio

2014-01-01

In this paper, we investigate the influence of the carbon content on the Cu-Te phase formation and on the resistive switching behavior in carbon alloyed Cu 0.6 Te 0.4 based conductive bridge random access memory (CBRAM) cells. Carbon alloying of copper-tellurium inhibits the crystallization, while attractive switching behavior is preserved when using the material as Cu-supply layer in CBRAM cells. The phase formation is first investigated in a combinatorial way. With increasing carbon content, an enlargement of the temperature window in which the material stays amorphous was observed. Moreover, if crystalline phases are formed, subsequent phase transformations are inhibited. The electrical switching behavior of memory cells with different carbon contents is then investigated by implementing them in 580 μm diameter dot TiN/Cu 0.6 Te 0.4 -C/Al 2 O 3 /Si memory cells. Reliable switching behavior is observed for carbon contents up to 40 at. %, with a resistive window of more than 2 orders of magnitude, whereas for 50 at. % carbon, a higher current in the off state and only a small resistive window are present after repeated cycling. This degradation can be ascribed to the higher thermal and lower drift contribution to the reset operation due to a lower Cu affinity towards the supply layer, leading cycle-after-cycle to an increasing amount of Cu in the switching layer, which contributes to the current. The thermal diffusion of Cu into Al 2 O 3 under annealing also gives an indication of the Cu affinity of the source layer. Time of flight secondary ion mass spectroscopy was used to investigate this migration depth in Al 2 O 3 before and after annealing, showing a higher Cu, Te, and C migration for high carbon contents

Influence of carbon content on the copper-telluride phase formation and on the resistive switching behavior of carbon alloyed Cu-Te conductive bridge random access memory cells

Science.gov (United States)

Devulder, Wouter; Opsomer, Karl; Franquet, Alexis; Meersschaut, Johan; Belmonte, Attilio; Muller, Robert; De Schutter, Bob; Van Elshocht, Sven; Jurczak, Malgorzata; Goux, Ludovic; Detavernier, Christophe

2014-02-01

In this paper, we investigate the influence of the carbon content on the Cu-Te phase formation and on the resistive switching behavior in carbon alloyed Cu0.6Te0.4 based conductive bridge random access memory (CBRAM) cells. Carbon alloying of copper-tellurium inhibits the crystallization, while attractive switching behavior is preserved when using the material as Cu-supply layer in CBRAM cells. The phase formation is first investigated in a combinatorial way. With increasing carbon content, an enlargement of the temperature window in which the material stays amorphous was observed. Moreover, if crystalline phases are formed, subsequent phase transformations are inhibited. The electrical switching behavior of memory cells with different carbon contents is then investigated by implementing them in 580 μm diameter dot TiN/Cu0.6Te0.4-C/Al2O3/Si memory cells. Reliable switching behavior is observed for carbon contents up to 40 at. %, with a resistive window of more than 2 orders of magnitude, whereas for 50 at. % carbon, a higher current in the off state and only a small resistive window are present after repeated cycling. This degradation can be ascribed to the higher thermal and lower drift contribution to the reset operation due to a lower Cu affinity towards the supply layer, leading cycle-after-cycle to an increasing amount of Cu in the switching layer, which contributes to the current. The thermal diffusion of Cu into Al2O3 under annealing also gives an indication of the Cu affinity of the source layer. Time of flight secondary ion mass spectroscopy was used to investigate this migration depth in Al2O3 before and after annealing, showing a higher Cu, Te, and C migration for high carbon contents.

Twinning behavior in the Ti-5at.% Al single crystals during cyclic loading along [0001

International Nuclear Information System (INIS)

Xiao Lin

2005-01-01

Cyclic deformation behavior of Ti-5at.% Al single crystals subjected to pull-push cyclic load along [0001] crystallographic orientation was studied. A higher cyclic stress response was displayed in the Ti-5Al single crystal oriented for [0001] than that oriented for single prism slip. Optical microscopy and transmission electron microscopy examinations show that twinning is a dominant plastic deformation mode in the single crystals during cycling. Trace analysis of prepolished surfaces was used to identify the twin systems primarily responsible for deformation. The major twin type observed was {101-bar 2}, {112-bar 2}, {101-bar 1} and {112-bar 1}. slip was observed in the neighboring region of twins in the fatigued specimens. The activation of multiple twinning systems contributed to the higher cyclic saturation stress in Ti-5Al single crystals oriented for [0001

Prevalence of Behavior Changing Strategies in Fitness Video Games: Theory-Based Content Analysis

OpenAIRE

Lyons, Elizabeth Jane; Hatkevich, Claire

2013-01-01

Background Fitness video games are popular, but little is known about their content. Because many contain interactive tools that mimic behavioral strategies from weight loss intervention programs, it is possible that differences in content could affect player physical activity and/or weight outcomes. There is a need for a better understanding of what behavioral strategies are currently available in fitness games and how they are implemented. Objective The purpose of this study was to investig...

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

scanning calorimetry (DSC) measurements. The data obtained from the stretched samples within 70-90 degrees C showed that all of the formed crystals are disordered alpha' form with more compact chain packing than that of the cold crystallization. Upon stretching at 70 degrees C, the mesocrystal appears......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...... 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...

Determination of rare earth element content in yttrium aluminium garnet crystals by absorption spectrophotometry method

International Nuclear Information System (INIS)

Mejl'man, M.L.; Kolomijtsev, A.I.; Baskakova, Z.M.; Bagdasarov, Kh.S.; Kevorkov, A.M.

1985-01-01

Possibility of determination of relative and absolute contents of impurity trivalent REE ions in yttrium aluminium garnet of (YAG) monocrystals has been studied by the absorption spectrophotometry method. Absorption spectra in UV and visible regions YAG monocrystals doped by REE are studied. For each admixture the characteristic lines or absorption bands not overlapping with lines of other admixtures are defined and investigated. The extinction coefficients of characteristic lines are determined which allow one to measure absolute REE admixture concentrations in garnet crystals. A conclusion is drawn that the absorption spectrophotometry method permits to measure REE admixture content in YAG monocrystals within the concentration range of approximately 1x10sup(-3)-5 mas. % with an accuracy not less than 20% (with sample thickness of approximately 1 cm)

Effect of Ta content on martensitic transformation behavior of RuTa ultrahigh temperature shape memory alloys

International Nuclear Information System (INIS)

He Zhirong; Zhou Jingen; Furuya, Y.

2003-01-01

Effects of Ta content on martensitic transformation (MT) behavior of Ru 100-x Ta x (x=46-54 at.%) alloys have been investigated by differential scanning calorimetry, dilatometry, X-ray diffraction and optical microscopy. Ta content significantly affects the MT behavior of RuTa alloys. The one-stage reservible MT occurs in Ta-poor RuTa alloys with Ta content less than 49 at.%. The two-stage reservible MT takes place in near-equiatomic RuTa alloys. No reservible MT is observed in Ta-rich alloys with Ta content more then 52 at.% Ta. The MT temperatures and hysteresis of RuTa alloys decrease with increasing Ta content. The aged and thermal cycled processes are nearly no effect on the MT behavior of these alloys. The deforming way of RuTa alloys is twinning. The Ru 50 Ta 50 alloy is of the most excellent MT behavior among these RuTa alloys

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.

Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Lewins, C. J., E-mail: c.j.lewins@bath.ac.uk; Le Boulbar, E. D.; Lis, S. M.; Shields, P. A.; Allsopp, D. W. E., E-mail: d.allsopp@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

2014-07-28

We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.

Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

Energy Technology Data Exchange (ETDEWEB)

Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com [Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

2016-06-21

Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

In situ observation of the role of alumina particles on the crystallization behavior of slags

Energy Technology Data Exchange (ETDEWEB)

Orrling, C.

2000-09-01

The confocal laser scanning microscope (CLSM) allows crystallization behavior in liquid slags to he observed in situ at high temperatures. Slags in the lime-silica-alumina-magnesia system are easily tinder cooled and it is possible to construct time temperature transformation (TTT) diagrams for this system. The presence of solid alumina particles its these liquid slags was studied to determine if these particles act as heterogeneous nucleation sites that cause she precipitation of solid material within slags. The introduction of alumina particles reduced the incubation time for the onset of crystallization and increased the temperature at which crystallization was observed in the slags to close to the liquidus temperature for the slag. Crystal growth rates are in a good agreement with Ivantsov's solution of the problem of diffusion controlled dendritic growth. Alumina appears to be a potent nucleating agent in the slag systems that were studied. (author)

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 fibers and the surrounding media (high humidity or water at 70 C) leads to chemical changes strongly affecting the surface morphology. The crystallization peak temperature of the basaltic glass fibers are increased without changing the onset temperature, this may be caused by a chemical depletion...

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.

Resistive switching behavior in single crystal SrTiO{sub 3} annealed by laser

Energy Technology Data Exchange (ETDEWEB)

Pan, Xinqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shuai, Yao, E-mail: yshuai@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wu, Chuangui, E-mail: cgwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Wenbo [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Sun, Xiangyu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Yuan, Ye; Zhou, Shengqiang [Helmholtz-Zentrum Dresden Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Ou, Xin [State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Wanli [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-12-15

Highlights: • Laser annealing was used to introduce oxygen vacancies into the single crystal SrTiO{sub 3}. • The effect of laser annealing with different fluence on the single crystal SrTiO{sub 3} was systematically studied. • The concentration of oxygen vacancies can be tuned by changing the fluence of laser. • Resistive switching behavior was observed in the sample with relatively high laser fluence after an electro-forming process. - Abstract: Single crystal SrTiO{sub 3} (STO) wafers were annealed by XeCl laser (λ = 308 nm) with different fluences of 0.4 J/cm{sup 2}, 0.6 J/cm{sup 2} and 0.8 J/cm{sup 2}, respectively. Ti/Pt electrodes were sputtered on the surface of STO wafer to form co-planar capacitor-like structures of Pt/Ti/STO/Ti/Pt. Current-Voltage measurements show that the leakage current is enhanced by increasing laser fluence. Resistive switching behavior is only observed in the sample annealed by laser with relatively high fluence after an electro-forming process. The X-ray photoelectron spectroscopy measurements indicate that the amount of oxygen vacancies increases with the increase of laser fluence. This work indicates resistive switching appears when enough oxygen vacancies are generated by the laser, which form conductive filaments under an external electric field.

Crystallization characteristic and scaling behavior of germanium antimony thin films for phase change memory.

Science.gov (United States)

Wu, Weihua; Zhao, Zihan; Shen, Bo; Zhai, Jiwei; Song, Sannian; Song, Zhitang

2018-04-19

Amorphous Ge8Sb92 thin films with various thicknesses were deposited by magnetron sputtering. The crystallization kinetics and optical properties of the Ge8Sb92 thin films and related scaling effects were investigated by an in situ thermally induced method and an optical technique. With a decrease in film thickness, the crystallization temperature, crystallization activation energy and data retention ability increased significantly. The changed crystallization behavior may be ascribed to the smaller grain size and larger surface-to-volume ratio as the film thickness decreased. Regardless of whether the state was amorphous or crystalline, the film resistance increased remarkably as the film thickness decreased to 3 nm. The optical band gap calculated from the reflection spectra increases distinctly with a reduction in film thickness. X-ray diffraction patterns confirm that the scaling of the Ge8Sb92 thin film can inhibit the crystallization process and reduce the grain size. The values of exponent indices that were obtained indicate that the crystallization mechanism experiences a series of changes with scaling of the film thickness. The crystallization time was estimated to determine the scaling effect on the phase change speed. The scaling effect on the electrical switching performance of a phase change memory cell was also determined. The current-voltage and resistance-voltage characteristics indicate that phase change memory cells based on a thinner Ge8Sb92 film will exhibit a higher threshold voltage, lower RESET operational voltage and greater pulse width, which implies higher thermal stability, lower power consumption and relatively lower switching velocity.

Relationships between molecular structure and kinetic and thermodynamic controls in lipid systems. Part III. Crystallization and phase behavior of 1-palmitoyl-2,3-stearoyl-sn-glycerol (PSS) and tristearoylglycerol (SSS) binary system.

Science.gov (United States)

Bouzidi, Laziz; Narine, Suresh S

2012-01-01

The phase behavior of 1-palmitoyl-2,3-distearoyl-sn-glycerol (PSS)/tristearoylglycerol (SSS) binary system was investigated in terms of polymorphism, crystallization and melting behavior, microstructure and solid fat content (SFC) using widely different constant cooling rates. Kinetic phase diagrams were experimentally determined from the DSC heating thermograms and analyzed using a thermodynamic model to account for non-ideality of mixing. The kinetic phase diagram presented a typical eutectic behavior with a eutectic point at the 0.5(PSS) mixture with a probable precipitation line from 0.5(PSS) to 1.0(PSS), regardless of the rate at which the sample was cooled. The eutectic temperature decreased only slightly with increasing cooling rate. PSS has a strong effect on the physical properties of the PSS-SSS mixtures. In fact, the overall phase behavior of the PSS-SSS binary system was determined, for a very large part, by the asymmetrical TAG. Moreover, PSS is a key driver of the high stability observed in crystal growth, polymorphism and phase development. Levels as low as 10% PSS, when cooled slowly, and 30% when cooled rapidly, were found to be sufficient to suppress the effect of thermal processing. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Crystal growth and properties of novel organic nonlinear optical crystals of 4-Nitrophenol urea

Energy Technology Data Exchange (ETDEWEB)

Mohan, M. Krishna, E-mail: krishnamohan.m@ktr.srmuniv.ac.in; Ponnusamy, S.; Muthamizhchelvan, C.

2017-07-01

Single crystals of 4-Nitrophenol urea have been grown from water using slow evaporation technique at constant temperature, with the vision to improve the properties of the crystals. The unit cell parameters of the grown crystals were determined by single crystal and powder X-Ray diffraction. FTIR studies reveals the presence of different vibrational bands. The Optical studies confirmed that the crystal is transparent up to 360 nm .TGA and DSC studies were carried out to understand the thermal behavior of crystals. The SHG studies show the suitability of the crystals for NLO applications. The etching studies were carried out to study the behavior of the crystals under different conditions.These studies reveal that the crystals of 4-Nitrophenol urea are suitable for device applications. - Highlights: • 4-Nitrophenol urea crystals of dimensions 14 mm × 1 mm were grown. • UV–Visible studies indicate the crystal is transparent in the region of 370–800 nm. • Thermal studies show the crystal starts decomposing at 170 °C. • SHG studies indicate that the crystals have NLO efficiency 3.5 times that of KDP.

Effects of Covalent Functionalization of MWCNTs on the Thermal Properties and Non-Isothermal Crystallization Behaviors of PPS Composites

Directory of Open Access Journals (Sweden)

Myounguk Kim

2017-09-01

Full Text Available In this study, a PPS/MWCNTs composite was prepared with poly(phenylene sulfide (PPS, as well as pristine and covalent functionalized multi-walled carbon nanotubes (MWCNTs via melt-blending techniques. Moreover, the dispersion of the MWCNTs on the PPS matrix was improved by covalent functionalization as can be seen from a Field-Emission Scanning Electron Microscope (FE-SEM images. The thermal properties of the PPS/MWCNTs composites were characterized using a thermal conductivity analyzer, and a differential scanning calorimeter (DSC. To analyze the crystallization behavior of polymers under conditions similar with those in industry, the non-isothermal crystallization behaviors of the PPS/MWCNTs composites were confirmed using various kinetic equations, such as the modified Avrami equation and Avrami-Ozawa combined equation. The crystallization rate of PPS/1 wt % pristine MWCNTs composite (PPSP1 was faster because of the intrinsic nucleation effect of the MWCNTs. However, the crystallization rates of the composites containing covalently-functionalized MWCNTs were slower than PPSP1 because of the destruction of the MWCNTs graphitic structure via covalent functionalization. Furthermore, the activation energies calculated by Kissinger’s method were consistently decreased by covalent functionalization.

Using the Integrative Model to Explain How Exposure to Sexual Media Content Influences Adolescent Sexual Behavior

Science.gov (United States)

Bleakley, Amy; Hennessy, Michael; Fishbein, Martin; Jordan, Amy

2011-01-01

Published research demonstrates an association between exposure to media sexual content and a variety of sex-related outcomes for adolescents. What is not known is the mechanism through which sexual content produces this "media effect" on adolescent beliefs, attitudes, and behavior. Using the Integrative Model of Behavioral Prediction, this…

Unique cold-crystallization behavior and kinetics of biodegradable poly[(butylene succinate)-co adipate] nanocomposites: a high speed differential scanning calorimetry study

CSIR Research Space (South Africa)

Bandyopadhyay, J

2014-08-01

Full Text Available . The effect of such structural changes on the cold-crystallization behavior and kinetics of PBSANCs were investigated using a high-speed DSC. Surprisingly, the DSC thermograms revealed that the characteristic cold-crystallization peak of neat PBSA shifts...

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.

Thermal behavior of asphalt cements

International Nuclear Information System (INIS)

Claudy, P.M.; Letoffe, J.M.; Martin, D.; Planche, J.P.

1998-01-01

Asphalt cements are highly complex mixtures of hydrocarbon molecules whose thermal behavior is of prime importance for petroleum and road industry. From DSC, the determination of several thermal properties of asphalts is given, e.g. glass-transition temperature and crystallized fraction content.The dissolution of a pure n-paraffin C n H 2n+2 in an asphalt, as seen by DSC, should be a single peak. For 20 g of these glasses change with time and temperature. The formation of the crystallized phases is superposed to the enthalpic relaxation of the glasses, making a kinetic study very difficult. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Non-isothermal crystallization kinetics and characterization of biodegradable poly(butylene succinate-co-neopentyl glycol succinate) copolyesters.

Science.gov (United States)

Xie, Wen-Jie; Zhou, Xiao-Ming

2015-01-01

Both biodegradable aliphatic neat poly(butylene succinate) (PBS) and poly(butylene succinate-co-neopentyl glycol succinate) (P(BS-co-NPGS)) copolyesters with different 1,4-butanediol/neopentyl glycol ratios were synthesized through a two-step process of transesterification and polycondensation using stannous chloride and 4-Methylbenzenesulfonic acid as the co-catalysts. The structure, non-isothermal crystallization behavior, crystalline morphology and crystal structure of neat PBS and P(BS-co-NPGS) copolyesters were characterized by (1)H NMR, differential scanning calorimetry (DSC), polarized optical microscope (POM) and wide angle X-ray diffraction (WAXD), respectively. The Avrami equation modified by Jeziorny and Mo's method was employed to describe the non-isothermal crystallization kinetics of the neat PBS and its copolyesters. The modified Avrami equation could adequately describe the primary stage of non-isothermal crystallization kinetics of the neat PBS and its copolyesters. Mo's method provided a fairly satisfactory description of the non-isothermal crystallization of neat PBS and its copolyesters. Interestingly, the values of 1/t1/2, Zc and F(T) obtained by the modified Avrami equation and Mo's method analysis indicated that the crystallization rate increased first and then decreased with an increase of NPGS content compared that of neat PBS, whereas the crystallization mechanism almost kept unchanged. The results of tensile testing showed that the ductility of PBS was largely improved by incorporating NPGS units. The elongation at break increased remarkably with increasing NPGS content. In particular, the sample with 20% NPGS content showed around 548% elongation at break. Copyright © 2014 Elsevier B.V. All rights reserved.

Hardening and strengthening behavior in rate-independent strain gradient crystal plasticity

DEFF Research Database (Denmark)

Nellemann, C.; Niordson, C. F.; Nielsen, K.L.

2018-01-01

Two rate-independent strain gradient crystal plasticity models, one new and one previously published, are compared and a numerical framework that encompasses both is developed. The model previously published is briefly outlined, while an in-depth description is given for the new, yet somewhat...... related,model. The difference between the two models is found in the definitions of the plastic work expended in the material and their relation to spatial gradients of plastic strains. The model predictions are highly relevant to the ongoing discussion in the literature, concerning 1) what governs...... the increase in the apparent yield stress due to strain gradients (also referred to as strengthening)? And 2), what is the implication of such strengthening in relation to crystalline material behavior at the micron scale? The present work characterizes material behavior, and the corresponding plastic slip...

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 press...

Non-isothermal crystallization kinetics and characterization of biodegradable poly(butylene succinate-co-neopentyl glycol succinate) copolyesters

International Nuclear Information System (INIS)

Xie, Wen-Jie; Zhou, Xiao-Ming

2015-01-01

Both biodegradable aliphatic neat poly(butylene succinate) (PBS) and poly(butylene succinate-co-neopentyl glycol succinate) (P(BS-co-NPGS)) copolyesters with different 1,4-butanediol/neopentyl glycol ratios were synthesized through a two-step process of transesterification and polycondensation using stannous chloride and 4-Methylbenzenesulfonic acid as the co-catalysts. The structure, non-isothermal crystallization behavior, crystalline morphology and crystal structure of neat PBS and P(BS-co-NPGS) copolyesters were characterized by 1 H NMR, differential scanning calorimetry (DSC), polarized optical microscope (POM) and wide angle X-ray diffraction (WAXD), respectively. The Avrami equation modified by Jeziorny and Mo's method was employed to describe the non-isothermal crystallization kinetics of the neat PBS and its copolyesters. The modified Avrami equation could adequately describe the primary stage of non-isothermal crystallization kinetics of the neat PBS and its copolyesters. Mo's method provided a fairly satisfactory description of the non-isothermal crystallization of neat PBS and its copolyesters. Interestingly, the values of 1/t 1/2 , Z c and F(T) obtained by the modified Avrami equation and Mo's method analysis indicated that the crystallization rate increased first and then decreased with an increase of NPGS content compared that of neat PBS, whereas the crystallization mechanism almost kept unchanged. The results of tensile testing showed that the ductility of PBS was largely improved by incorporating NPGS units. The elongation at break increased remarkably with increasing NPGS content. In particular, the sample with 20% NPGS content showed around 548% elongation at break. - Highlights: • The incorporation of NPGS units reduced the spherulite size of BS unit. • The existence of NPGS units did not change the crystal structure of BS unit. • The NPGS units incorporated in PBS could significantly improve the ductility of PBS. • The

Magmatic water contents determined through clinopyroxene: Examples from the Western Canary Islands, Spain

Science.gov (United States)

Weis, Franz A.; Skogby, Henrik; Troll, Valentin R.; Deegan, Frances M.; Dahren, Börje

2015-07-01

Water is a key parameter in magma genesis, magma evolution, and resulting eruption styles, because it controls the density, the viscosity, as well as the melting and crystallization behavior of a melt. The parental water content of a magma is usually measured through melt inclusions in minerals such as olivine, a method which may be hampered, however, by the lack of melt inclusions suitable for analysis, or postentrapment changes in their water content. An alternative way to reconstruct the water content of a magma is to use nominally anhydrous minerals (NAMs), such as pyroxene, which take up low concentrations of hydrogen as a function of the magma's water content. During magma degassing and eruption, however, NAMs may dehydrate. We therefore tested a method to reconstruct the water contents of dehydrated clinopyroxene phenocrysts from the Western Canary islands (n = 28) through rehydration experiments followed by infrared and Mössbauer spectroscopy. Employing currently available crystal/melt partitioning data, the results of the experiments were used to calculate parental water contents of 0.71 ± 0.07 to 1.49 ± 0.15 wt % H2O for Western Canary magmas during clinopyroxene crystallization at upper mantle conditions. This H2O range is in agreement with calculated water contents using plagioclase-liquid-hygrometry, and with previously published data for mafic lavas from the Canary Islands and comparable ocean island systems elsewhere. Utilizing NAMs in combination with hydrogen treatment can therefore serve as a proxy for pre-eruptive H2O contents, which we anticipate becoming a useful method applicable to mafic rocks where pyroxene is the main phenocryst phase.

Studying effect of MoO{sub 3} on elastic and crystallization behavior of lithium diborate glasses

Energy Technology Data Exchange (ETDEWEB)

Shaaban, KH.S.; Abd Elnaeim, A.M. [El-Azhar University, Physics Department, Faculty of Science, Assiut (Egypt); Abo-naf, S.M. [National Research Centre, Glass Research Department, Cairo (Egypt); Hassouna, M.E.M. [Beni-Suef University, Chemistry Department, Faculty of Science, Beni Suef (Egypt)

2017-06-15

The effect of MoO{sub 3} addition on the crystallization characteristics of 2Al{sub 2}O{sub 3}-23Li{sub 2}O-(75 - x) B{sub 2}O{sub 3} glass (where x MoO{sub 3} = 0, 10, 20, and 40 mol %) has been investigated. The compositional dependence of the glass transition (T{sub g}), and crystallization (T{sub c}) temperatures was determined by the differential thermal analysis (DTA). It was found that both the T{sub g} and T{sub c} decrease with increasing MoO{sub 3} content. The amorphous nature of the as-quenched glass and crystallinity of the produced glass-ceramics were confirmed by X-ray powder diffraction (XRD) analysis. Glass-ceramics embedded with diomignite (lithium diborate, Li{sub 2}B{sub 4}O{sub 7}) were produced from all investigated glasses by heat-treating the as-quenched glasses at the appropriate temperatures obtained from the DTA traces. Addition of MoO{sub 3} to the glass composition at 10% MoO{sub 3}, causes the formation of lithium molybdenum oxide (Li{sub 4}MoO{sub 5}) crystalline phase in addition to the diomignite phase. Increasing MoO{sub 3} content to 20% causes a phase transformation of lithium molybdenum oxide from the (Li{sub 4}MoO{sub 5}) to the (Li{sub 2}MoO{sub 4}) phase and the formation of another lithium borate (Li{sub 4}B{sub 2}O{sub 5}) phase in addition to the diomignite. Further increase of MoO{sub 3} content to 40% results in another phase transformation to the lithium aluminum molybdenum oxide [LiAl(MoO{sub 4}){sub 2}], and, in this case, the molybdenum content was excess enough to crystallize the molybdate (MoO{sub 3}) itself. Scanning electron microscopy (SEM) was used to characterize the morphology and microstructure of the formed solid solution phases. The values of the T{sub g} decrease with increasing the MoO{sub 3} content. The ultrasonic wave velocities and elastic moduli were determined using the pulse-echo method. Both velocities (v{sub L} and v{sub T}) were increased as the MoO{sub 3} content, this increase can be

Sintering and crystallization behavior of CaMgSi2O6-NaFeSi2O6 based glass-ceramics

International Nuclear Information System (INIS)

Goel, Ashutosh; Kansal, Ishu; Ferrari, Anna Maria; Pascual, Maria J.; Barbieri, Luisa; Bondioli, Federica; Lancellotti, Isabella; Ribeiro, Manuel J.; Ferreira, Jose M. F.

2009-01-01

We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi 2 O 6 -10 mol % NaFeSi 2 O 6 . The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850-950 deg. C in both air and N 2 atmosphere. X-ray diffraction studies adjoined with the Rietveld-reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions.

Health Behavior Theory in Popular Calorie Counting Apps: A Content Analysis

OpenAIRE

Davis, Siena F; Ellsworth, Marisa A; Payne, Hannah E; Hall, Shelby M; West, Joshua H; Nordhagen, Amber L

2016-01-01

Background Although the Health & Fitness category of the Apple App Store features hundreds of calorie counting apps, the extent to which popular calorie counting apps include health behavior theory is unknown. Objective This study evaluates the presence of health behavior theory in calorie counting apps. Methods Data for this study came from an extensive content analysis of the 10 most popular calorie counting apps in the Health & Fitness category of the Apple App Store. Results Each app was ...

Investigation of crystallization kinetics and deformation behavior in supercooled liquid region of CuZr-based bulk metallic glass

Energy Technology Data Exchange (ETDEWEB)

Yang, Ke; Fan, Xinhui; Li, Bing; Li, Yanhong; Wang, Xin; Xu, Xuanxuan [Xi' an Technological Univ. (China). School of Material and Chemical Engineering

2017-08-15

In this paper, a systematic study of crystallization kinetics and deformation behavior is presented for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} bulk metallic glass in the supercooled liquid region. Crystallization results showed that the activation energy for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} was calculated using the Arrhenius equation in isothermal mode and the Kissinger-Akahira-Sunose method in non-isothermal mode. The activation energy was quite high compared with other bulk metallic glasses. Based on isothermal transformation kinetics described by the Johson-Mehl-Avrami model, the average Avrami exponent of about 3.05 implies a mainly diffusion controlled three-dimensional growth with an increasing nucleation rate during the crystallization. For warm deformation, the results showed that deformation behavior, composed of homogeneous and inhomogeneous deformation, is strongly dependent on strain rate and temperature. The homogeneous deformation transformed from non-Newtonian flow to Newtonian flow with a decrease in strain rate and an increase in temperature. It was found that the crystallization during high temperature deformation is induced by heating. The appropriate working temperature/strain rate combination for the alloy forming, without in-situ crystallization, was deduced by constructing an empirical deformation map. The optimum process condition for (Cu{sub 50}Zr{sub 50}){sub 94}Al{sub 6} can be expressed as T∝733 K and ∝ ε 10{sup -3} s{sup -1}.

Thermal expansion of LATGS crystals

International Nuclear Information System (INIS)

Kassem, M.E.; Kandil, S.H.; Hamed, A.E.; Stankowska, J.

1989-04-01

The thermal expansion of triglycine sulphate crystals doped with L-α alanine (LATGS) has been studied around the phase transition temperature (30-60 deg. C) using thermomechanical analysis TMA. With increasing the content of admixture, the transition temperature (T c ) was shifted towards higher values, while the relative changes in the dimension of the crystals (ΔL/L 0 ) of the studied directions varied both in the para- and ferroelectric phases. The transition width in the case of doped crystals was found to be broad, and this broadening increases with increasing the content of L-α alanine. (author). 12 refs, 3 figs

Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

CSIR Research Space (South Africa)

Malwela, T

2014-01-01

Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

Behavioral determinants of cardiovascular diseases risk factors: A qualitative directed content analysis.

Science.gov (United States)

Sabzmakan, Leila; Morowatisharifabad, Mohammad Ali; Mohammadi, Eesa; Mazloomy-Mahmoodabad, Seid Saied; Rabiei, Katayoun; Naseri, Mohammad Hassan; Shakibazadeh, Elham; Mirzaei, Masoud

2014-03-01

The PRECEDE model is a useful tool for planers to assess health problems, the behavioral and environmental causes of the problems, and their determinants. This study aims to understand the experiences of patients and health care providers about the behavioral causes of cardiovascular diseases (CVDs) risk factors and their determinants. This qualitative study utilized content analysis approach based on the PRECEDE model. The study was conducted for over 6 months in 2012 at the diabetes units of health centers associated with Alborz University of Medical Sciences, which is located in Karaj, Iran. Data were collected using individual semi-structured interviews with 50 patients and 12 health care providers. Data analysis was performed simultaneously with data collection using the content analysis directed method. Stress, unhealthy eating, and physical inactivity were the behaviors, which predict the risk factors for CVD. Most of the patients considered stress as the most important underlying cause of their illness. In this study, 110 of the primary codes were categorized into seven subcategories, including knowledge, attitude, perceived susceptibility, severity, perceived benefits, barriers, and self-efficacy, which were located in the predisposing category of the PRECEDE model. Among these determinants, perceived barriers and self-efficacy for the mentioned behaviors seemed to be of great importance. Identifying behavioral determinants will help the planners design future programs and select the most appropriate methods and applications to address these determinants in order to reduce risky behaviors.

Effect of cellulose nanocrystals (CNC) on rheological and mechanical properties and crystallization behavior of PLA/CNC nanocomposites.

Science.gov (United States)

Kamal, Musa R; Khoshkava, Vahid

2015-06-05

In earlier work, we reported that spray freeze drying of cellulose nanocrystals (CNC) yields porous agglomerate structures. On the other hand, the conventional spray dried CNC (CNCSD) and the freeze dried CNC (CNCFD) produce compact solid structures with very low porosity. As it is rather difficult to obtain direct microscopic evidence of the quality of dispersion of CNC in polymer nanocomposites, it was shown that supporting evidence of the quality and influence of dispersion in a polypropylene (PP)/CNC nanocomposite could be obtained by studying the rheological behavior, mechanical properties and crystallization characteristics of PP/CNC nanocomposites. In an effort to produce a sustainable, fully biosourced, biodegradable nanocomposite, this manuscript presents the results of a study of the rheological, mechanical and crystallization behavior of PLA/CNCSFD nanocomposites obtained by melt processing. The results are analyzed to determine CNC network formation, rheological percolation threshold concentrations, mechanical properties in the rubbery and glassy states, and the effect of CNCSFD on crystalline nucleation and crystallization rates of PLA. These results suggest that the porosity and network structure of CNCSFD agglomerates contribute significantly to good dispersion of CNC in the PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mutual Influence of Special Components in Baotou Steel Blast Furnace Slag on the Crystallization Behavior of Glass

OpenAIRE

Wang, Yici; Jiang, Qi; Luo, Guoping; Yu, Wenwu; Ban, Yan

2012-01-01

In the process of glass-ceramics prepared with Baotou steel blast furnace slag, quartz sand, and other raw materials by melting method, the mutual influence of the special components such as CaF2, REXOY, TiO2, K2O, and Na2O in the blast furnace slag on the crystallization behavior of parent glass was investigated using differential thermal analysis (DTA) and X-ray diffraction (XRD). The results show that the special components in slag can reduce the crystallization temperature and promote cry...

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

Poly(L-lactide) (PLLA)/graphene nanosheet (GNS) composites and pure PLLA were prepared by the solution blending method. Crystalline structures and crystallization behaviors of PLLA in the composite were investigated by XRD, POM, SAXS, and DSC. It was found that α′ form PLLA formation seemed...

Study of the phenomena of crystallization of paraffin in the fluid-dynamic behavior of paraffinic crude - Phase 1

International Nuclear Information System (INIS)

Rodriguez, L; Castaneda, M

2001-01-01

The results obtained by relating the formation of wax crystals using traditional measurements such as cloud point, pour point and viscosity show the importance of analyzing the interactions among the chemical nature of crude oils, the physical-chemical variables and the fluid dynamics that cause different shapes and rates of crystallization. In addition, the specific value of viscosity should be measured at a certain temperature, as well as the rheological behavior of the crude oils during the process of formation and destruction of crystals due to shear rate. In order to carry out this study, a group of waxy crude oils was chosen. They were characterized considering the parameters mentioned above, and they were subjected to different cooling rates to microscopically observe the resulting morphologies, and to relate them to rheological behavior in a range of similar conditions that are obtained during hydrocarbon transport through pipelines. For this effect, laboratory tests were carried out, in addition to the scaling of results at the pilot plant level in a simulator to analyze the behavior of the fluids in dynamic or static conditions, in relation to prolonged pipeline downtime. This type of studies improves operational safety, offers considerable savings on additives, power, an increase in pumping capacity, and it also facilitates the selection of the most appropriate technology to control wax deposition

The measurement of the uranium content of crystals, glasses and meteorites with the fission track method

International Nuclear Information System (INIS)

Vartanian, R.

1977-04-01

In the present investigation, work has been carried out regarding the measurement of the uranium content of minerals, crystals and meteoritic samples from different parts of Iran. In this paper the method of inducing tracks from the 235 U indigenous to the Solid State Nuclear Track Detectors (SSNTDS) is described and new results have been attained. These are summarized as follows: Apatite between (4.16+-0.27) and (10.54+-0.84) ppm, Wulfnite=(4.90+-0.37) ppm, Quartz=(0.15+-0.02) ppm and Meteorite=(0.026+-0.003) ppm. (author)

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.

Structural and functional characterization of HPHT diamond crystals used in photoconductive devices

Energy Technology Data Exchange (ETDEWEB)

Pace, E.; Pini, A. [Florence Univ. (Italy). Ist. di Astronomia; Vinattieri, A.; Bogani, F.; Santoro, M.; Messina, G.; Santangelo, S.; Sato, Y.

2000-09-01

Diamond films are extensively studied for applications as functional material for UV photoconductors. CVD-grown polycrystalline diamond films show very interesting performances, but their complete exploitation is actually limited by a slow time response if compared to other materials, by a relatively high concentration of structural defects, impurities and grain boundaries, which may affect the collection length of photogenerated charges. High-quality single crystal diamonds could solve some of these problems. The absence of grain boundaries can produce longer collection lengths. The nitrogen and impurity contents can be reduced and then large type-IIa diamond single-crystals can be obtained. In this work, a detailed structural and functional characterization of type Ib HPHT diamond crystals has been carried out and the results have been compared to similar characterizations of CVD films to evaluate the different behavior, taking also into account that these high pressure high temperature (HPHT) diamond crystals contain several tens ppm of nitrogen. (orig.)

Health Behavior Theory in Physical Activity Game Apps: A Content Analysis.

Science.gov (United States)

Payne, Hannah E; Moxley, Victor Ba; MacDonald, Elizabeth

2015-07-13

Physical activity games developed for a mobile phone platform are becoming increasingly popular, yet little is known about their content or inclusion of health behavior theory (HBT). The objective of our study was to quantify elements of HBT in physical activity games developed for mobile phones and to assess the relationship between theoretical constructs and various app features. We conducted an analysis of exercise and physical activity game apps in the Apple App Store in the fall of 2014. A total of 52 apps were identified and rated for inclusion of health behavior theoretical constructs using an established theory-based rubric. Each app was coded for 100 theoretical items, containing 5 questions for 20 different constructs. Possible total theory scores ranged from 0 to 100. Descriptive statistics and Spearman correlations were used to describe the HBT score and association with selected app features, respectively. The average HBT score in the sample was 14.98 out of 100. One outlier, SuperBetter, scored higher than the other apps with a score of 76. Goal setting, self-monitoring, and self-reward were the most-reported constructs found in the sample. There was no association between either app price and theory score (P=.5074), or number of gamification elements and theory score (P=.5010). However, Superbetter, with the highest HBT score, was also the most expensive app. There are few content analyses of serious games for health, but a comparison between these findings and previous content analyses of non-game health apps indicates that physical activity mobile phone games demonstrate higher levels of behavior theory. The most common theoretical constructs found in this sample are known to be efficacious elements in physical activity interventions. It is unclear, however, whether app designers consciously design physical activity mobile phone games with specific constructs in mind; it may be that games lend themselves well to inclusion of theory and any

Fundamental study on dissolution behavior of poly(methyl methacrylate) by quartz crystal microbalance

Science.gov (United States)

Konda, Akihiro; Yamamoto, Hiroki; Yoshitake, Shusuke; Kozawa, Takahiro

2016-03-01

Ionizing radiations such as extreme ultraviolet (EUV) and electron beam (EB) are the most promising exposure source for next-generation lithographic technology. In the realization of high resolution lithography, it is necessary for resist materials to improve the trade-off relationship among sensitivity, resolution, and line width roughness (LWR). In order to overcome them, it is essential to understand basic chemistry of resist matrices in resist processes. In particular, the dissolution process of resist materials is a key process. Therefore, it is essential for next-generation resist design for ionizing radiation to clarify the dissolution behavior of the resist film into developer. However, the details in dissolution process of EUV and EB resist films have not been investigated thus far. In this study, main chain scission and dissolution behavior of poly(methyl methacrylate) (PMMA) as main chain scission type resist was investigated using quartz crystal microbalance (QCM) method and gel permeation chromatography (GPC) in order to understand the relationship between the degree of PMMA degradation and dissolution behavior. The relationship between the molecular weight after irradiation and the swelling behavior was clarified.

Effect of aluminum content on the passivation behavior of Fe-Al alloys in sulfuric acid solution

DEFF Research Database (Denmark)

Chiang, Wen-Chi; Luu, W.C.; Wu, J.K.

2006-01-01

-Al alloys, which the Al content of alloy exceeds 19 at %, have wide passivation regions with low passivation current. However, when the Al content of Fe-Al alloys exceeds this range, the increment of Al content has slight influence on passivation behavior compared with ternary Cr addition....

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.

Mathematical model to analyze the dissolution behavior of metastable crystals or amorphous drug accompanied with a solid-liquid interface reaction.

Science.gov (United States)

Hirai, Daiki; Iwao, Yasunori; Kimura, Shin-Ichiro; Noguchi, Shuji; Itai, Shigeru

2017-04-30

Metastable crystals and the amorphous state of poorly water-soluble drugs in solid dispersions (SDs), are subject to a solid-liquid interface reaction upon exposure to a solvent. The dissolution behavior during the solid-liquid interface reaction often shows that the concentration of drugs is supersaturated, with a high initial drug concentration compared with the solubility of stable crystals but finally approaching the latter solubility with time. However, a method for measuring the precipitation rate of stable crystals and/or the potential solubility of metastable crystals or amorphous drugs has not been established. In this study, a novel mathematical model that can represent the dissolution behavior of the solid-liquid interface reaction for metastable crystals or amorphous drug was developed and its validity was evaluated. The theory for this model was based on the Noyes-Whitney equation and assumes that the precipitation of stable crystals at the solid-liquid interface occurs through a first-order reaction. Moreover, two models were developed, one assuming that the surface area of the drug remains constant because of the presence of excess drug in the bulk and the other that the surface area changes in time-dependency because of agglomeration of the drug. SDs of Ibuprofen (IB)/polyvinylpyrrolidone (PVP) were prepared and their dissolution behaviors under non-sink conditions were fitted by the models to evaluate improvements in solubility. The model assuming time-dependent surface area showed good agreement with experimental values. Furthermore, by applying the model to the dissolution profile, parameters such as the precipitation rate and the potential solubility of the amorphous drug were successfully calculated. In addition, it was shown that the improvement in solubility with supersaturation was able to be evaluated quantitatively using this model. Therefore, this mathematical model would be a useful tool to quantitatively determine the supersaturation

Crystallization Stages of the Bishop Tuff Magma Body Recorded in Crystal Textures in Pumice Clasts

Energy Technology Data Exchange (ETDEWEB)

Pamukcu, Ayla; Gualda, Guilherme A.R.; Anderson, Jr. , Alfred T. (Vanderbilt); (UC)

2012-07-25

The Bishop Tuff is a giant silicic ignimbrite erupted at 0.76 Ma in eastern California, USA. Five pumice clasts from the late-erupted Bishop Tuff (Aeolian Buttes) were studied in an effort to better understand the pre- and syn-eruptive history of the Bishop magma body and place constraints on the timescales of its existence. This study complements and expands on a previous study that focused on early-erupted Bishop Tuff pumice clasts. Bulk densities of pumice clasts were measured using an immersion method, and phenocryst crystal contents were determined using a sieving and winnowing procedure. X-ray tomography was used to obtain qualitative and quantitative textural information, particularly crystal size distributions (CSDs). We have determined CSDs for crystals ranging in size from {approx}10 to {approx}1000 {micro}m for three groups of mineral phases: magnetite ({+-}ilmenite), pyroxene + biotite, quartz + feldspar. Similar to early-erupted pumice, late-erupted pumice bulk density and crystal contents are positively correlated, and comparison of crystal fraction vs size trends suggests that the proportion of large crystals is the primary control on crystallinity. Porosity is negatively correlated with crystal content, which is difficult to reconcile with closed-system crystallization. Magnetite and pyroxene + biotite size distributions are fractal in nature, often attributed to fragmentation; however, crystals are mostly whole and euhedral, such that an alternative mechanism is necessary to explain these distributions. Quartz + feldspar size distributions are kinked, with a shallow-sloped log-linear section describing large crystals (> 140 {micro}m) and a steep-sloped log-linear section describing small crystals (< 140 {micro}m). We interpret these two crystal populations as resulting from a shift in crystallization regime. We suggest that the shallow-sloped section describes a pre-eruptive quartz + feldspar growth-dominated regime, whereas the steep

Synthesis of SAPO-56 with controlled crystal size

Energy Technology Data Exchange (ETDEWEB)

Wu, Ting; Feng, Xuhui [Colorado School of Mines, Chemical and Biological Engineering Department (United States); Carreon, Maria L. [University of Tulsa, Rusell School of Chemical Engineering (United States); Carreon, Moises A., E-mail: mcarreon@mines.edu [Colorado School of Mines, Chemical and Biological Engineering Department (United States)

2017-03-15

Herein, we present the hydrothermal synthesis of SAPO-56 crystals with relatively controlled crystal/particle size. The effects of water content, aluminum source, gel composition, stirring, crystallization temperature and time, as well as the incorporation of crystal growth inhibitors during synthesis were systematically investigated. The synthesized SAPO-56 crystals displayed BET surface areas as high as ∼630 m{sup 2} g{sup −1} with relative narrow size distribution in the ∼5–60 μm range. Nitrogen BET surface areas in the 451 to 631 m{sup 2} g{sup −1} range were observed. Decreasing the crystallization temperature from 220 to 210 °C helped to decrease the average SAPO-56 crystal size. Diluted gel compositions promoted the formation of smaller crystals. Crystal growth inhibitors were found to be helpful in reducing crystal size and narrow the size distribution. Specifically, ∼5 μm SAPO-56 crystals displaying narrow size distribution were synthesized employing aluminum-tri-sec-butoxide as Al source, high water content, and high stirring rates.

Synthesis of SAPO-56 with controlled crystal size

International Nuclear Information System (INIS)

Wu, Ting; Feng, Xuhui; Carreon, Maria L.; Carreon, Moises A.

2017-01-01

Herein, we present the hydrothermal synthesis of SAPO-56 crystals with relatively controlled crystal/particle size. The effects of water content, aluminum source, gel composition, stirring, crystallization temperature and time, as well as the incorporation of crystal growth inhibitors during synthesis were systematically investigated. The synthesized SAPO-56 crystals displayed BET surface areas as high as ∼630 m"2 g"−"1 with relative narrow size distribution in the ∼5–60 μm range. Nitrogen BET surface areas in the 451 to 631 m"2 g"−"1 range were observed. Decreasing the crystallization temperature from 220 to 210 °C helped to decrease the average SAPO-56 crystal size. Diluted gel compositions promoted the formation of smaller crystals. Crystal growth inhibitors were found to be helpful in reducing crystal size and narrow the size distribution. Specifically, ∼5 μm SAPO-56 crystals displaying narrow size distribution were synthesized employing aluminum-tri-sec-butoxide as Al source, high water content, and high stirring rates.

The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

Directory of Open Access Journals (Sweden)

Eskandar Moghimipour

2013-01-01

Full Text Available Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC, polyvinyl pyrrolidone (PVP, tragacanth, and magnesium aluminum silicate (Veegum were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F, redispersibility (n, and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions.

The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

Science.gov (United States)

Moghimipour, Eskandar; Kouchak, Maryam; Salimi, Anayatollah; Bahrampour, Saeed; Handali, Somayeh

2013-01-01

Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), tragacanth, and magnesium aluminum silicate (Veegum) were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F), redispersibility (n), and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions. PMID:24109512

Ultratight crystal packing of a 10 kDa protein

Energy Technology Data Exchange (ETDEWEB)

Trillo-Muyo, Sergio [Molecular Biology Institute of Barcelona, Spanish Research Council CSIC, Barcelona Science Park, c/Baldiri Reixac 15-21, 08028 Barcelona (Spain); Jasilionis, Andrius [Vilnius University, M. K. Čiurlionio 21/27, 03101 Vilnius (Lithuania); Domagalski, Marcin J. [University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0736 (United States); Chruszcz, Maksymilian [University of South Carolina, 631 Sumter Street, Columbia, SC 29208 (United States); Minor, Wladek [University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA 22908-0736 (United States); Kuisiene, Nomeda [Vilnius University, M. K. Čiurlionio 21/27, 03101 Vilnius (Lithuania); Arolas, Joan L.; Solà, Maria; Gomis-Rüth, F. Xavier, E-mail: xgrcri@ibmb.csic.es [Molecular Biology Institute of Barcelona, Spanish Research Council CSIC, Barcelona Science Park, c/Baldiri Reixac 15-21, 08028 Barcelona (Spain)

2013-03-01

The crystal structure of the C-terminal domain of a putative U32 peptidase from G. thermoleovorans is reported; it is one of the most tightly packed protein structures reported to date. While small organic molecules generally crystallize forming tightly packed lattices with little solvent content, proteins form air-sensitive high-solvent-content crystals. Here, the crystallization and full structure analysis of a novel recombinant 10 kDa protein corresponding to the C-terminal domain of a putative U32 peptidase are reported. The orthorhombic crystal contained only 24.5% solvent and is therefore among the most tightly packed protein lattices ever reported.

Structure and phase formation behavior and dielectric and magnetic properties of lead iron tantalate-lead zirconate titanate multiferroic ceramics

International Nuclear Information System (INIS)

Wongmaneerung, R.; Tipakontitikul, R.; Jantaratana, P.; Bootchanont, A.; Jutimoosik, J.; Yimnirun, R.; Ananta, S.

2016-01-01

Highlights: • The multiferroic ceramics consisted of PFT and PZT. • Crystal structure changed from cubic to mixedcubic and tetragonal with increasing PZT content. • Dielectric showed the samples underwent a typical relaxor ferroelectric behavior. • Magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops. - Abstract: Multiferroic (1 − x)Pb(Fe_0_._5Ta_0_._5)O_3–xPb(Zr_0_._5_3Ti_0_._4_7)O_3 (or PFT–PZT) ceramics were synthesized by solid-state reaction method. The crystal structure and phase formation of the ceramics were examined by X-ray diffraction (XRD). The local structure surrounding Fe and Ti absorbing atoms was investigated by synchrotron X-ray Absorption Near-Edge Structure (XANES) measurement. Dielectric properties were studied as a function of frequency and temperature using a LCR meter. A vibrating sample magnetometer (VSM) was used to determine the magnetic hysteresis loops. XRD study indicated that the crystal structure of the sample changed from pure cubic to mixed cubic and tetragonal with increasing PZT content. XANES measurements showed that the local structure surrounding Fe and Ti ions was similar. Dielectric study showed that the samples underwent a typical relaxor ferroelectric behavior while the magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops.

Effect of tensile mean stress on fatigue behavior of single-crystal and directionally solidified superalloys

Science.gov (United States)

Kalluri, Sreeramesh; Mcgaw, Michael A.

1990-01-01

Two nickel base superalloys, single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf, were studied in view of the potential usage of the former and usage of the latter as blade materials for the turbomachinery of the space shuttle main engine. The baseline zero mean stress (ZMS) fatigue life (FL) behavior of these superalloys was established, and then the effect of tensile mean stress (TMS) on their FL behavior was characterized. At room temperature these superalloys have lower ductilities and higher strengths than most polycrystalline engineering alloys. The cycle stress-strain response was thus nominally elastic in most of the fatigue tests. Therefore, a stress range based FL prediction approach was used to characterize both the ZMS and TMS fatigue data. In the past, several researchers have developed methods to account for the detrimental effect of tensile mean stress on the FL for polycrystalline engineering alloys. However, the applicability of these methods to single crystal and directionally solidified superalloys has not been established. In this study, these methods were applied to characterize the TMS fatigue data of single crystal PWA 1480 and directionally solidified MAR-M 246 + Hf and were found to be unsatisfactory. Therefore, a method of accounting for the TMS effect on FL, that is based on a technique proposed by Heidmann and Manson was developed to characterize the TMS fatigue data of these superalloys. Details of this method and its relationship to the conventionally used mean stress methods in FL prediction are discussed.

Effects of crystal refining on wear behaviors and mechanical properties of lithium disilicate glass-ceramics.

Science.gov (United States)

Zhang, Zhenzhen; Guo, Jiawen; Sun, Yali; Tian, Beimin; Zheng, Xiaojuan; Zhou, Ming; He, Lin; Zhang, Shaofeng

2018-05-01

The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment. In the meantime, heat-pressed lithium disilicate glass-ceramics (GC-P) and original ingots (GC-O) were used as control groups. Glass-ceramics were characterized using X-ray diffraction (XRD) and were tested using flexural strength test, nanoindentation test and toughness measurements. The plate specimens were dynamically loaded in a chewing simulator with 350 N up to 2.4 × 10 6 loading cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 300,000 wear cycles. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pairwise comparisons of means were performed by Tukey's post-hoc test. Materials with different crystal sizes (p properties. Specifically, G3 with medium-sized crystals presented the highest flexural strength, hardness, elastic modulus and fracture toughness. G1 and G2 with small-sized crystals showed lower flexural strength, whereas G4, GC-P, and GC-O with large-sized crystals exhibited lower hardness and elastic modulus. The wear behaviors of all six groups showed running-in wear stage and steady wear stage. G3 showed the best wear resistance while GC-P and GC-O exhibited the highest wear volume loss. After crystal refining, lithium disilicate glass-ceramic with medium-sized crystals showed the highest wear resistance and mechanical properties. Copyright © 2018

Health Behavior Theory in Physical Activity Game Apps: A Content Analysis

Science.gov (United States)

Moxley, Victor BA; MacDonald, Elizabeth

2015-01-01

Background Physical activity games developed for a mobile phone platform are becoming increasingly popular, yet little is known about their content or inclusion of health behavior theory (HBT). Objective The objective of our study was to quantify elements of HBT in physical activity games developed for mobile phones and to assess the relationship between theoretical constructs and various app features. Methods We conducted an analysis of exercise and physical activity game apps in the Apple App Store in the fall of 2014. A total of 52 apps were identified and rated for inclusion of health behavior theoretical constructs using an established theory-based rubric. Each app was coded for 100 theoretical items, containing 5 questions for 20 different constructs. Possible total theory scores ranged from 0 to 100. Descriptive statistics and Spearman correlations were used to describe the HBT score and association with selected app features, respectively. Results The average HBT score in the sample was 14.98 out of 100. One outlier, SuperBetter, scored higher than the other apps with a score of 76. Goal setting, self-monitoring, and self-reward were the most-reported constructs found in the sample. There was no association between either app price and theory score (P=.5074), or number of gamification elements and theory score (P=.5010). However, Superbetter, with the highest HBT score, was also the most expensive app. Conclusions There are few content analyses of serious games for health, but a comparison between these findings and previous content analyses of non-game health apps indicates that physical activity mobile phone games demonstrate higher levels of behavior theory. The most common theoretical constructs found in this sample are known to be efficacious elements in physical activity interventions. It is unclear, however, whether app designers consciously design physical activity mobile phone games with specific constructs in mind; it may be that games lend

Crystal growth and characterization of a semiorganic nonlinear optical single crystal of gamma glycine

International Nuclear Information System (INIS)

Prakash, J. Thomas Joseph; Kumararaman, S.

2008-01-01

Gamma glycine has been successfully synthesized by taking glycine and potassium chloride and single crystals have been grown by solvent evaporation method for the first time. The grown single crystals have been analyzed with XRD, Fourier transform infrared (FTIR), and thermo gravimetric and differential thermal analyses (TG/DTA) measurements. Its mechanical behavior has been assessed by Vickers microhardness measurements. Its nonlinear optical property has been tested by Kurtz powder technique. Its optical behavior was examined by UV-vis., and found that the crystal is transparent in the region between 240 and 1200 nm. Hence, it may be very much useful for the second harmonic generation (SHG) applications

Investigation of element contents of natural diamond crystals of different gemological features by INAA and autoradiography

International Nuclear Information System (INIS)

Khamrayeva, D.S.; Ulugmuradov, S.; Didyk, A.Y.; Gasanov, M.; Solodova, J.P.; Sedova, E.A.

2004-01-01

Full text: The work presented aims at understanding the role of Co, Ni, Ti, Cr, Mn, Cu impurities on the natural diamond ( Type Ι ) quality, microstructure and morphology having different gemological features for identification their deposit. An according of the Kimberly Process there is Certification Scheme for regulating trade in diamonds to exclude 'bloody' diamonds. The 'four C's' criteria (color, clarity, carat weight, cut) had for decades been used by gemologists worldwide to evaluate precious gem diamonds. Those four parameters were believed to determine the value of the stones. Some 10 years ago gemologists added to those traditional criteria a fifth C, signifying Confidence. The role of the fifth C in pricing precious stones increased over time. An according of the Kimberly Process it is necessary to determine diamond deposit. Impurity content of natural diamonds is basic feature to for identification their deposit. We have used autoradiographic technique for investigation of spatial impurity distributions in natural diamond crystals. It is based on the secondary beta irradiation registration. Impurities were identified by energy lines of the gamma spectra obtained and by half-life periods. We bring information which allow to clarify the spatial distributions of Co, Ni, Ti, Cr, Mn, Cu impurities depended inner morphology of diamond crystal. It was established several types of impurity distributions depending from inner morphology of diamond crystals. Results of INAA and autoradiographic study of natural diamonds use for to make of international data for identification their deposit

Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains.

Directory of Open Access Journals (Sweden)

Jie Min

Full Text Available The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains.Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated.The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes.Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.

Design of Agglomerated Crystals of Ibuprofen During Crystallization: Influence of Surfactant

Directory of Open Access Journals (Sweden)

Maryam Maghsoodi

2011-01-01

Full Text Available Objective(sIbuprofen is a problematic drug in tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surface. Because of the bad compaction behavior ibuprofen has to be granulated usually before tableting. However, it would be more satisfactory to obtain directly during the crystallization step crystalline particles that can be directly compressed and quickly dissolved. Materials and Methods Crystallization of ibuprofen was carried out using the quasi emulsion solvent diffusion method in presence of surfactant (sodium lauryl sulfate (SLS, Tween 80. The particles were characterized by differential scanning calorimetry (DSC, powder X-ray diffraction (XRPD and were evaluated for particle size, flowability, drug release and tableting behavior. ResultsIbuprofen particles obtained in the presence of surfactants consisted of numerous plate- shaped crystals which had agglomerated together as near spherical shape. The obtained agglomerates exhibited significantly improved micromeritic properties as well as tableting behavior than untreated drug crystals. The agglomerates size and size distribution was largely controlled by surfactant concentration, but there was no significant influence found on the tableting properties. The dissolution tests showed that the agglomerates obtained in presence of SLS exhibited enhanced dissolution rate while the agglomerates made in the presence of Tween 80 had no significant impact on dissolution rate of ibuprofen in comparison to untreated sample. The XRPD and DSC results showed that during the agglomeration process, ibuprofen did not undergo any polymorphic changes.Conclusion The study highlights the influence of surfactants on crystallization process leading to modified performance.

Influence of iron on crystallization behavior and thermal stability of the insulating materials - porous calcium silicates

DEFF Research Database (Denmark)

Haastrup, Sonja; Yu, Donghong; Yue, Yuanzheng

2017-01-01

The properties of porous calcium silicate for high temperature insulation are strongly influenced by impurities. In this work we determine the influence of Fe3+ on the crystallization behavior and thermal stability of hydrothermally derived calcium silicate. We synthesize porous calcium silicate...... with Ca/Si molar ratio of 1, to which Fe2O3 is added with Fe/Si molar ratios of 0.1, 0.5, 0.7, 1.0, and 1.3%. Structure and morphology of the porous calcium silicate, with different iron concentrations, are investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). FTIR...... measurements reveal a pronounced decrease in the number of Q3 sites in the calcium silicate with an increase of Fe3+, and thereby lower the crystal fraction of xonotlite (Ca6Si6O17(OH)2) phase, and increase the crystal fractions of tobermorite(Ca5Si6O16(OH)2·4H2O) and calcite (CaCO3) phases, as confirmed...

Crystallization behavior and mechanical properties of nano-CaCO3/β-nucleated ethylene-propylene random copolymer composites

Directory of Open Access Journals (Sweden)

W. H. Ruan

2012-09-01

Full Text Available To provide ethylene-propylene random copolymer (PPR with balanced mechanical properties, β-nucleating agent and CaCO3 nanoparticles are incorporated into PPR matrix by melt blending. It is found that crystallization rate and relative content of β-crystal increase with the addition of β-nucleating agent together with nanoparticles. Size of PPR spherulite is greatly reduced, and a specific morphology appears, in which α-crystal lamella is grown upon the β-nucleus. The results suggest that both β-nucleating agent and nano-CaCO3 have heterogeneous nucleation and synergistic effects on β-nucleation of PPR. Mechanical characterization shows that mechanical properties of PPR can be tuned by incorporation of β-nucleating agent and nano-CaCO3 particles. Under suitable compositions, low temperature impact strength and high temperature creep resistance of PPR, the bottlenecks of application of such material, can be simultaneously improved without sacrificing the Youngs’modulus and tensile strength.

Tensile behavior of nickel-base single-crystal superalloy DD6

Energy Technology Data Exchange (ETDEWEB)

Xiong, Xinhong, E-mail: xiongxh@whut.edu.cn [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Quan, Dunmiao; Dai, Pengdan; Wang, Zhiping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Zhang, Qiaoxin [School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070 (China); Yue, Zhufeng [School of Mechanics Civil Engineering and Architecture, Northwestern Polytechnical University, Xi' an 710072 (China)

2015-06-11

Tensile behavior of the nickel-base single-crystal superalloy DD6 was studied from room temperature to 1020 °C. The plate specimens were along [001] orientation parallel to the loading axis in tension. The microstructures on the surface and fracture morphology were investigated after tensile test to rupture by scanning electron microscopy (SEM). The results of the present investigation indicate that the yield strength at 650 °C is superior to that at room temperature, 850 °C and 1020 °C. Low ductility and serrated flow in stress–strain curves were also observed at 650 °C. The microstructures on the surface of the plate specimens and fracture morphology observation indicated that localized slip which resulted in glide plane decohesion caused the low ductility of DD6 alloy.

On the crystal growth and chemistry of the new electron-type superconducting oxides

Energy Technology Data Exchange (ETDEWEB)

Tarascon, J.M.; Wang, E.; Greene, L.H.; Ramesh, R.; Bagley, B.G.; Hull, G.W.; Miceli, P.F. (Bellcore, Red Bank, NJ (USA)); Wang, Z.Z.; Brawner, D.; Ong, N.P. (Dept. of Physics, Princeton Univ., NJ (USA))

1989-12-01

The effect on transport and superconducting properties produced by changes in x and y in the Nd{sub 2-x}Ce{sub x}CuO{sub y} compound were studied in both polycrystalline ceramics and single crystals. Thermogravimetric analysis shows that the total oxygen content y for the as-prepared samples is always greater than 4 (i.e. presence of interstitial oxygen) whereas for the reduced sample y becomes equal to or smaller than 4 only when x is 0.15 or greater. This is the range of Ce content for which the material superconducts. For a material with Ce x=0.15 the superconducting properties can be varied reversibly by changing the oxygen content. In addition, we propose that the oxygen in these materials can be either ordered or disordered, thereby affecting the transport properties. Platelet-like crystals of Nd{sub 2-x}Ce{sub x}CuO{sub y} with x=0 to 0.18, have been grown via a flux technique. Those having a Ce content between 0.14 and 0.17 are superconducting with the sharpest transitions (Tc=21{plus minus}1K) for x=0.14. Metallic-like behavior above Tc, with a linear temperature dependence above 150K was observed on all the crystals. Below 30K, the in-plane resistivity is independent of T. The Hall coefficient is sensitive to processing conditions but is usually negative above 100K. The upper critical field with field along the c-axis is 6T at 4.2K. (orig.).

[Relationship between cognitive content and emotions following dilatory behavior: considering the level of trait procrastination].

Science.gov (United States)

Hayashi, Junichiro

2009-02-01

The present study developed and evaluated the Automatic Thoughts List following Dilatory Behavior (ATL-DB) to explore the mediation hypothesis and the content-specificity hypothesis about the automatic thoughts with trait procrastination and emotions. In Study 1, data from 113 Japanese college students were used to choose 22 items to construct the ATL-DB. Two factors were indentified, I. Criticism of Self and Behavior, II. Difficulty in Achievement. These factors had high degrees of internal consistency and had positive correlations to trait procrastination. In Study 2, the relationships among trait procrastination, the automatic thoughts, depression, and anxiety were examined in 261 college students by using Structural Equation Modeling. The results showed that the influence of trait procrastination on depression was mainly mediated through Criticism of Self and Behavior only, while the influence of trait procrastination to anxiety was mediated through Criticism of Self and Behavior and Difficulty in Achievement. Therefore, the mediation hypothesis was supported and the content-specificity hypothesis was partially supported.

Inducing Behavioral Change in Seekers of Pro-Anorexia Content Using Internet Advertisements: Randomized Controlled Trial.

Science.gov (United States)

Yom-Tov, Elad; Brunstein-Klomek, Anat; Mandel, Or; Hadas, Arie; Fennig, Silvana

2018-02-22

The influence of pro-anorexia (pro-ana) websites is debated, with studies indicating both negative and positive effects, as well as significant variation in the effects of different websites for those suffering from eating disorders (EDs) and the general population. Online advertising, known to induce behavioral change both online and in the physical world, has not been used so far to modify the search behavior of people seeking pro-ana content. The objective of this randomized controlled trial (RCT) was to examine if online advertisements (ads) can change online search behaviors of users who are looking for online pro-ana content. Using the Bing Ads system, we conducted an RCT to randomly expose the searchers for pro-ana content to 10 different ads referring people to one of the three websites: the National Eating Disorders Association, the National Institutes of Mental Health, and MyProAna. MyProAna is a pro-ana website that was found in a previous study to be associated with less pathological online behaviors than other pro-ana websites. We followed participants exposed and unexposed to the ads to explore their past and future online searches. The ads were shown 25,554 times and clicked on 217 times. Exposure to the ads was associated with a decrease in searches for pro-ana and self-harm content. Reductions were greatest among those referred to MyProAna (reduction of 34.0% [73/215] and 37.2% [80/215] for pro-ana and self-harm, respectively) compared with users who were referred elsewhere (reduction of 15.47% [410/2650] and 3.21% [85/2650], respectively), and with users who were not shown the ads, who increased their behaviors (increase of 57.12% [6462/11,314] and 4.07% [461/11,314], respectively). In addition, those referred to MyProAna increased their search for treatment, as did control users, who did so to a lesser extent. However, users referred elsewhere decreased their searches for this content. We found that referring users interested in ED

Fatigue crack growth behavior of a new single crystal nickel-based superalloy (CMSX-4) at 650 C

International Nuclear Information System (INIS)

Sengupta, A.; Putatunda, S.K.

1994-01-01

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

Measurement of the Ru surface content of electrodeposited PtRu electrodes with the electrochemical quartz crystal microbalance: implications for methanol and CO electrooxidation

NARCIS (Netherlands)

Frelink, T.; Visscher, W.; Veen, van J.A.R.

1996-01-01

To obtain the surface content of Ru in rough electrocodeposited PtRu electrodes, the mass change of a Pt electrode during Ru deposition was measured with the electrochemical quartz crystal microbalance (EQCMB). It is shown that there is a correlation between the potential of the surface oxide

Magnetism and thermal induced characteristics of Fe{sub 2}O{sub 3} content bioceramics

Energy Technology Data Exchange (ETDEWEB)

Wu, Chun-Shiang; Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Hsu, Fang-Chi, E-mail: fangchi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Wang, Moo-Chin [Department of Fragrance and Cosmetics, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Chen, Yung-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 803, Taiwan (China)

2012-11-15

Magnetic properties of Li{sub 2}O-MnO{sub 2}-CaO-P{sub 2}O{sub 5}-SiO{sub 2} (LMCPS) glasses doped with various amounts of Fe{sub 2}O{sub 3} were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe{sub 2}O{sub 3} and crystallized at 850 Degree-Sign C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe{sub 2}O{sub 3} exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe{sub 2}O{sub 3} content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe{sub 2}O{sub 3} content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics. - Highlights: Black-Right-Pointing-Pointer Presence of Fe{sub 2}O{sub 3} in LMCPS glass ceramic promotes the growth of (Li, Mn)ferrite. Black-Right-Pointing-Pointer The amount of Fe{sub 2}O{sub 3} determines the size of (Li,Mn)ferrite particles. Black-Right-Pointing-Pointer Room temperature superparamagnetism was obtained at 4 at% of Fe{sub 2}O{sub 3} addition. Black-Right-Pointing-Pointer In addition, Li(Mn, Fe)ferrite phase contributes to the magnetic energy loss. Black-Right-Pointing-Pointer The largest energy loss is the trade-off between the ferrite content and Mn/Fe ratio.

Global low-energy weak solution and large-time behavior for the compressible flow of liquid crystals

Science.gov (United States)

Wu, Guochun; Tan, Zhong

2018-06-01

In this paper, we consider the weak solution of the simplified Ericksen-Leslie system modeling compressible nematic liquid crystal flows in R3. When the initial data are of small energy and initial density is positive and essentially bounded, we prove the existence of a global weak solution in R3. The large-time behavior of a global weak solution is also established.

Behavior change techniques implemented in electronic lifestyle activity monitors: a systematic content analysis.

Science.gov (United States)

Lyons, Elizabeth J; Lewis, Zakkoyya H; Mayrsohn, Brian G; Rowland, Jennifer L

2014-08-15

Electronic activity monitors (such as those manufactured by Fitbit, Jawbone, and Nike) improve on standard pedometers by providing automated feedback and interactive behavior change tools via mobile device or personal computer. These monitors are commercially popular and show promise for use in public health interventions. However, little is known about the content of their feedback applications and how individual monitors may differ from one another. The purpose of this study was to describe the behavior change techniques implemented in commercially available electronic activity monitors. Electronic activity monitors (N=13) were systematically identified and tested by 3 trained coders for at least 1 week each. All monitors measured lifestyle physical activity and provided feedback via an app (computer or mobile). Coding was based on a hierarchical list of 93 behavior change techniques. Further coding of potentially effective techniques and adherence to theory-based recommendations were based on findings from meta-analyses and meta-regressions in the research literature. All monitors provided tools for self-monitoring, feedback, and environmental change by definition. The next most prevalent techniques (13 out of 13 monitors) were goal-setting and emphasizing discrepancy between current and goal behavior. Review of behavioral goals, social support, social comparison, prompts/cues, rewards, and a focus on past success were found in more than half of the systems. The monitors included a range of 5-10 of 14 total techniques identified from the research literature as potentially effective. Most of the monitors included goal-setting, self-monitoring, and feedback content that closely matched recommendations from social cognitive theory. Electronic activity monitors contain a wide range of behavior change techniques typically used in clinical behavioral interventions. Thus, the monitors may represent a medium by which these interventions could be translated for

Content and effects of news stories about uncertain cancer causes and preventive behaviors.

Science.gov (United States)

Niederdeppe, Jeff; Lee, Theodore; Robbins, Rebecca; Kim, Hye Kyung; Kresovich, Alex; Kirshenblat, Danielle; Standridge, Kimberly; Clarke, Christopher E; Jensen, Jakob; Fowler, Erika Franklin

2014-01-01

This article presents findings from two studies that describe news portrayals of cancer causes and prevention in local TV and test the effects of typical aspects of this coverage on cancer-related fatalism and overload. Study 1 analyzed the content of stories focused on cancer causes and prevention from an October 2002 national sample of local TV and newspaper cancer coverage (n = 122 television stations; n = 60 newspapers). Informed by results from the content analysis, Study 2 describes results from a randomized experiment testing effects of the volume and content of news stories about cancer causes and prevention (n = 601). Study 1 indicates that local TV news stories describe cancer causes and prevention as comparatively more certain than newspapers but include less information about how to reduce cancer risk. Study 2 reveals that the combination of stories conveying an emerging cancer cause and prevention behavior as moderately certain leads to an increased sense of overload, while a short summary of well-established preventive behaviors mitigates these potentially harmful beliefs. We conclude with a series of recommendations for health communication and health journalism practice.

Taxonomy-based content analysis of sedentary behavior questionnaires: A systematic review

Science.gov (United States)

Rivière, Fabien; Aubert, Salomé; Omorou, Abdou Yacoubou; Ainsworth, Barbara E.

2018-01-01

Background Health effects of sedentary behaviors (SB) may vary depending on their characteristics such as type, purpose, duration, and intensity of the behavior. While a growing number of questionnaires assess sedentary behaviors, it is unclear which characteristics of SB are measured. The aim of this review was to examine the content of self-report SB questionnaires. Methods Three databases were searched for sedentary behavior questionnaires published before January 1st, 2016. Based on the inclusion criteria, 82 articles out of 1369 were retrieved for a total of 60 questionnaires. For each questionnaire, the sedentary behavior characteristics identified were reported and analyzed. Results Most of the questionnaires assessed the time (n = 60), posture (n = 54), purpose (n = 46) and the types (n = 45) of SB performed. Fewer questionnaires assessed the environment (n = 20) social context (n = 11), status (n = 2), and associated behaviors (n = 2) related to sedentary behaviors. All the questionnaires except two assessed time spent in SB with 17 assessing frequency and 6 assessing breaks in SB. The most frequent characteristics identified in the questionnaires were the categories of sitting (90%), a day (95%), watching television (65%) and using a computer (55%). Many characteristics of SB were not measured. Conclusions By knowing the breadth of SB included in questionnaires, this review provides support to shape the design of new questionnaires designed to reduce the gaps in measuring sedentary behaviors. PMID:29509791

Molecular Dynamics Study on Nucleation Behavior and Lamellar Mergence of Polyethylene Globule Crystallization

Science.gov (United States)

Yang, Xiaozhen; Wang, Simiao

2012-02-01

The site order parameter (SOP) has been adopted to analyze various order structure formation and distribution during the crystallization of a multi-chain polyethylene globule simulated by molecular dynamics. We found that the nucleation relies on crystallinity fluctuation with increase of amplitude, and the baby nucleus in the fluctuation suddenly appears with different shape and increasing size. In the growth stage, a number of lamellar mergence was observed and their selective behaviors were suggested to be related to the orientation difference between the merging lamellae. We obtained that SOP distribution of all atoms in the system during crystallization appears with two peaks: one for the amorphous phase and the other for the crystalline phase. Mesomorphic structures with medium orders locate between the two peaks as an order promotion pathway. Obtained data show that the medium order structure fluctuates at the growth front and does not always be available; the medium order structure existing at the front is not always good for developing. It is possibly caused by chain entanglement.

User-Generated Content and travel planning: An application of the Theory of Planned Behavior

Directory of Open Access Journals (Sweden)

Luiz Augusto Machado Mendes Filho

2012-12-01

Full Text Available User-Generated Content (UGC such as online travel reviews written by travelers and posted to virtual communities are being used more frequently to communicate travel-related information. UGC is therefore helping travelers to make decisions about their travel. Utilizing the Theory of Planned Behavior (TPB, which is one of the most comprehensive models explaining behavioral intention, this study contributes to the further development of theories of online consumer behavior by determining which factors are most important in relation to the use of UGC in the travel industry. The TPB has three independent determinants of behavioral intention: attitude toward the behavior, subjective norm, and perceived behavior control. Therefore the aim of this paper is to examine the roles of attitude, subjective norm and perceived behavior control in respect of travelers’ intention to use UGC when making travel plans.

Structure and phase formation behavior and dielectric and magnetic properties of lead iron tantalate-lead zirconate titanate multiferroic ceramics

Energy Technology Data Exchange (ETDEWEB)

Wongmaneerung, R., E-mail: re_nok@yahoo.com [Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Tipakontitikul, R. [Department of Physics, Ubonratchathani University, Ubonratchathani 31490 (Thailand); Jantaratana, P. [Department of Physics, Kasetsart University, Bangkok 10900 (Thailand); Bootchanont, A.; Jutimoosik, J.; Yimnirun, R. [School of Physics, Institute of Science, and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Ananta, S. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2016-03-15

Highlights: • The multiferroic ceramics consisted of PFT and PZT. • Crystal structure changed from cubic to mixedcubic and tetragonal with increasing PZT content. • Dielectric showed the samples underwent a typical relaxor ferroelectric behavior. • Magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops. - Abstract: Multiferroic (1 − x)Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}–xPb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} (or PFT–PZT) ceramics were synthesized by solid-state reaction method. The crystal structure and phase formation of the ceramics were examined by X-ray diffraction (XRD). The local structure surrounding Fe and Ti absorbing atoms was investigated by synchrotron X-ray Absorption Near-Edge Structure (XANES) measurement. Dielectric properties were studied as a function of frequency and temperature using a LCR meter. A vibrating sample magnetometer (VSM) was used to determine the magnetic hysteresis loops. XRD study indicated that the crystal structure of the sample changed from pure cubic to mixed cubic and tetragonal with increasing PZT content. XANES measurements showed that the local structure surrounding Fe and Ti ions was similar. Dielectric study showed that the samples underwent a typical relaxor ferroelectric behavior while the magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops.

Synergistic Effects of Nucleating Agents and Plasticizers on the Crystallization Behavior of Poly(lactic acid

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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.

Crystallization of nodular cast iron with carbides

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S. Pietrowski

2008-12-01

Full Text Available In this paper a crystallization process of nodular cast iron with carbides having a different chemical composition have been presented. It have been found, that an increase of molybdenum above 0,30% causes the ledeburutic carbides crystallization after (γ+ graphite eutectic phase crystallization. When Mo content is lower, these carbides crystallize as a pre-eutectic phase. In this article causes of this effect have been given.

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. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Mitigating crystallization of saturated FAMES (fatty acid methyl esters) in biodiesel: 4. The phase behavior of 1,3-dioleoyl-2-palmitoyl glycerol – Methyl stearate binary system

International Nuclear Information System (INIS)

Mohanan, Athira; Bouzidi, Laziz; Narine, Suresh S.

2016-01-01

The present study examines the phase behavior of a model binary system made of OPO (1,3-dioleoyl-2-palmitoyl glycerol); a TAG (triacylglycerol) highly effective in depressing onset of crystallization of biodiesel, and MeS (methyl stearate); a prevalent saturated FAMEs (fatty acid methyl esters) in biodiesel. The thermal behavior, crystal structure and microstructure of the OPO/MeS mixtures were investigated with DSC (differential scanning calorimetry), XRD (X-ray diffraction) and PLM (polarized light microscope). The OPO/MeS system presented a phase diagram with peritectic and eutectic transitions. A simple thermodynamic modeling of the liquidus line indicated a relatively complex mixing behavior, and highlighted the prevailing effect of the peritectic compound on solubility. Different types of microstructures that were more or less influenced by MeS, OPO or/and compound microstructures were observed in the mixtures. They are associated with the crystal phases and the thermal transitions. Furthermore, MeS, OPO and compound crystal structures (monoclinic, orthorhombic and triclinic, respectively) served as templates for the crystal forms of the coexisting phases. The singularities in the liquidus line are attributed to chain length mismatch between the palmitic acid and the FAME (fatty acid methyl ester). The phase diagram achieved for OPO/MeS system is complete and can help in designing additive formulations to improve the cold flow behavior of biodiesel. - Highlights: • 1,3-dioleoyl-2-palmitoyl glycerol/methyl stearate (OPO/MeS) studied in detail. • Phase diagram with thermal transitions, polymorphism, microstructure achieved. • Phase trajectory singularities attributed to length mismatch of linear chains. • Mechanism for disruption of crystallization of biodiesel evidenced and explained.

NATO Advanced Research Workshop on Incommensurate Crystals, Liquid Crystals, and Quasi-Crystals

CERN Document Server

Clark, N

1988-01-01

In this NATO-sponsored Advanced Research Workshop we succeeded in bringing together approximately forty scientists working in the three main areas of structurally incommensurate materials: incommensurate crystals (primarily ferroelectric insulators), incommensurate liquid crystals, and metallic quasi-crystals. Although these three classes of materials are quite distinct, the commonality of the physics of the origin and descrip­ tion of these incommensurate structures is striking and evident in these proceedings. A measure of the success of this conference was the degree to which interaction among the three subgroups occurred; this was facili­ tated by approximately equal amounts of theory and experiment in the papers presented. We thank the University of Colorado for providing pleasant housing and conference facilities at a modest cost, and we are especially grate­ ful to Ann Underwood, who retyped all the manuscripts into camera-ready form. J. F. Scott Boulder, Colorado N. A. Clark v CONTENTS PART I: INCO...

Modelling the influence of carbon content on material behavior during forging

Science.gov (United States)

Korpała, G.; Ullmann, M.; Graf, M.; Wester, H.; Bouguecha, A.; Awiszus, B.; Behrens, B.-A.; Kawalla, R.

2017-10-01

Nowadays the design of single process steps and even of whole process chains is realized by the use of numerical simulation, in particular finite element (FE) based methods. A detailed numerical simulation of hot forging processes requires realistic models, which consider the relevant material-specific parameters to characterize the material behavior, the surface phenomena, the dies as well as models for the machine kinematic. This data exists partial for several materials, but general information on steel groups depending on alloying elements are not available. In order to generate the scientific input data regarding to material modelling, it is necessary to take into account the mathematical functions for deformation behavior as well as recrystallization kinetic, which depends alloying elements, initial microstructure and reheating mode. Besides the material flow characterization, a detailed description of surface changes caused by oxide scale is gaining in importance, as these phenomena affect the material flow and the component quality. Experiments to investigate the influence of only one chemical element on the oxide scale kinetic and the inner structure at high temperatures are still not available. Most data concerning these characteristics is provided for the steel grade C45, so this steel will be used as basis for the tests. In order to identify the effect of the carbon content on the material and oxidation behavior, the steel grades C15 and C60 will be investigated. This paper gives first approaches with regard to the influence of the carbon content on the oxide scale kinetic and the flow stresses combined with the initial microstructure.

RETRACTED: Growth behavior and microstructure evolution of ZnO nanorods grown on Si in aqueous solution

Science.gov (United States)

Liou, Sz-Chian; Hsiao, Chi-Sheng; Chen, San-Yuan

2005-02-01

This article has been retracted: please see Elsevier Policy on Article Withdrawal. This article has been retracted at the request of the Editor-in-Chief. Two papers published in the Journal of Crystal Growth are being retracted due to a case of misrepresentation and reuse of data. A reader of the Journal has brought to our attention the reuse of data within two published papers: Growth behavior and microstructure evolution of ZnO nanorods grown on Si in aqueous solution, Sz-Chian Liou, Chi-Sheng Hsiao, San-Yuan Chen, Journal of Crystal Growth 274 (2005) 438-446. Nucleation and growth behavior of well-aligned ZnO nanorods on organic substrates in aqueous solutions, Chin-Ching Lin, San-Yuan Chen, and Syh-Yuh Cheng, Journal of Crystal Growth 283 (2005) 141-146. In these papers the same transmission electron micrograph was used to describe two different experimental situations and results bringing into question the content of these papers. The reuse of data without proper attribution is not acceptable within the scientific publishing community. In the present case, this is compounded by the attribution of the micrograph to a different experimental situation and drawing, as a result, new conclusions from data obtained from different samples. Such behavior undermines the integrity of the scientific publishing endeavor and is not acceptable. The authors are responsible for the content of their papers.

Mitigating crystallization of saturated FAMEs in biodiesel 6: The binary phase behavior of 1, 2-dioleoyl-3-stearoyl sn-glycerol – Methyl stearate

International Nuclear Information System (INIS)

Mohanan, Athira; Bouzidi, Laziz; Narine, Suresh S.

2016-01-01

The derivatives of vegetable oils with specific chemical structures, such as TAG (triacylglycerols) having mixed straight and kinked moieties, have proven very effective in lowering the crystallization of biodiesel. SOO (1, 2-dioleoyl-3-stearoyl sn-glycerol)/MeS (methyl stearate) is part of a series of studies of TAG/FAME (fatty acid methyl ester) binary model systems conducted to establish structure–function relationships of lipid-based cold flow improvers in biodiesel with a particular attention to the effect of molecular symmetry in contrast with a previously published study of the OSO (1, 3-dioleoyl-2-stearoyl sn-glycerol)/MeS binary system. The phase behavior of several SOO/MeS mixtures were investigated at different length scales with XRD (X-ray diffraction), DSC (differential scanning calorimetry) and PLM (polarized light microscope). A complete phase diagram including the transformation lines, crystal structure and microstructure was constructed. The solubility behavior was discussed using a simple thermodynamic model based on the Hildebrand equation and pair interactions. The asymmetric position of the oleic moieties of SOO was shown to be crucial in modifying the thermal transformation behavior of MeS. The findings may be used to design effective crystallization modifiers of biodiesel based on particular structural determinants, and underscores the importance of symmetry in such designs. - Highlights: • Effect of symmetry of triglyceride on biodiesel crystallization established. • Complete phase diagram of model triacylglycerol/biodiesel binary system achieved. • Correlation between thermal transitions, crystal structure and microstructure revealed. • Transformation points useful for improving the cold flow of biodiesel identified. • Necessary knowledge gathered to design effective biodiesel cold flow improvers.

Effect of heat-treatment on microstructure and high-temperature deformation behavior of a low rhenium-containing single crystal nickel-based superalloy

International Nuclear Information System (INIS)

Sun, Nairong; Zhang, Lanting; Li, Zhigang; Shan, Aidang

2014-01-01

A low rhenium-containing [001] oriented single crystal nickel-based superalloy with different γ′ morphologies induced by various aging treatments was compressed from room temperature to 1000 °C. All the single crystal samples with different γ′ morphologies exhibit anomalous yield behavior. The sample first aged at 1180 °C has the widest anomalous temperature domain and highest yield strengths. The sample first aged at 1000 °C has the highest anomalous peak stress temperature

Shape memory and actuation behavior of semicrystalline polymer networks

Energy Technology Data Exchange (ETDEWEB)

Bothe, Martin

2014-07-01

Shape memory polymers (SMPs) can change their shape on application of a suitable stimulus. To enable such behavior, a 'programming' procedure fixes a deformation, yielding a stable temporary shape. In thermoresponsive SMPs, subsequent heating triggers entropy-elastic recovery of the initial shape. An additional shape change on cooling, i.e. thermoreversible two-way actuation, can be stimulated by a crystallization phenomenon. In this thesis, cyclic thermomechanical measurements systematically determined (1) the shape memory and (2) the actuation behavior under constant load as well as under stress-free conditions. Chemically cross-linked, star-shaped polyhedral oligomeric silsesquioxane polyurethane (SPOSS-PU) hybrid polymer networks and physically cross-linked poly(ester urethane) (PEU) block copolymers were investigated around the melting and crystallization temperatures of their polyester soft segments. (1) The SPOSS-PUs showed excellent shape fixities and recoverabilities of almost 100% at high cross-linking density, while PEUs exhibited pronounced shape memory properties at increased soft segment content. Furthermore, two-fold programmed SPOSS-PU specimens were able to recover their initial shape in two thermally separated events. Even a neck, which formed during deformation of SPOSS-PUs with high soft segment content, was reversed. (2) In PEUs, globally oriented crystallization on cooling drove expansion of the sample, in particular at high soft segment content and after application of a strong deformation. Melting reversed that orientation; the PEU sample contracted and thereby completed the thermoreversible actuation cycle. Under load, multiple polymorphic phase transitions enabled two successive expansion and contraction steps, while under stress-free conditions various geometric shape changes, including the increase and decrease of PEU sample length and thickness as well as twisting and untwisting could be experimentally witnessed. Such

Shape memory and actuation behavior of semicrystalline polymer networks

International Nuclear Information System (INIS)

Bothe, Martin

2014-01-01

Shape memory polymers (SMPs) can change their shape on application of a suitable stimulus. To enable such behavior, a 'programming' procedure fixes a deformation, yielding a stable temporary shape. In thermoresponsive SMPs, subsequent heating triggers entropy-elastic recovery of the initial shape. An additional shape change on cooling, i.e. thermoreversible two-way actuation, can be stimulated by a crystallization phenomenon. In this thesis, cyclic thermomechanical measurements systematically determined (1) the shape memory and (2) the actuation behavior under constant load as well as under stress-free conditions. Chemically cross-linked, star-shaped polyhedral oligomeric silsesquioxane polyurethane (SPOSS-PU) hybrid polymer networks and physically cross-linked poly(ester urethane) (PEU) block copolymers were investigated around the melting and crystallization temperatures of their polyester soft segments. (1) The SPOSS-PUs showed excellent shape fixities and recoverabilities of almost 100% at high cross-linking density, while PEUs exhibited pronounced shape memory properties at increased soft segment content. Furthermore, two-fold programmed SPOSS-PU specimens were able to recover their initial shape in two thermally separated events. Even a neck, which formed during deformation of SPOSS-PUs with high soft segment content, was reversed. (2) In PEUs, globally oriented crystallization on cooling drove expansion of the sample, in particular at high soft segment content and after application of a strong deformation. Melting reversed that orientation; the PEU sample contracted and thereby completed the thermoreversible actuation cycle. Under load, multiple polymorphic phase transitions enabled two successive expansion and contraction steps, while under stress-free conditions various geometric shape changes, including the increase and decrease of PEU sample length and thickness as well as twisting and untwisting could be experimentally witnessed. Such actuation

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.

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)

Hsu, Yu-Wei; Yang, Ko-Ho; Chang, Kuo-Ming; Yeh, Sung-Wei; Wang, Moo-Chin

2011-01-01

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 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 2 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 ZrO 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.

Effect of free Cr content on corrosion behavior of 3Cr steels in a CO2 environment

Science.gov (United States)

Li, Wei; Xu, Lining; Qiao, Lijie; Li, Jinxu

2017-12-01

The corrosion behavior of 3Cr steels with three microstructures (martensite, bainite, combined ferrite and pearlite) in simulated oil field formation water with a CO2 partial pressure of 0.8 MPa was investigated. The relationships between Cr concentrations in corrosion scales and corrosion rates were studied. The precipitated phases that contained Cr were observed in steels of different microstructures, and free Cr content levels were compared. The results showed that steel with the martensite microstructure had the highest free Cr content, and thus had the highest corrosion resistance. The free Cr content of bainite steel was lower than that of martensite steel, and the corrosion rate of bainite steel was higher than that of martensite steel. Because large masses of Cr were combined in ferrite and pearlite steel, the corrosion rates of ferrite and pearlite steel were the highest. Free Cr content in steel affects its corrosion behavior greatly.

Borassus flabellifer L. Brown Crystal Sugar Processing (The Study of Sap pH and Fine Crystal Sucrose (FCS Concentration

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Azmi Alvian Gabriel

2017-04-01

Full Text Available Nira as one of the Borassus flabellirer L. products has a similar characteristics with other agricultural commodities that are easily damaged. This research aims to know the influence of nira’s pH and concentration addition of FCS against characteristics of the brown crystal sugar. Research compiled by using Randomized Block Design (RBD which comprises two factors consisting of 3 levels with 3 times replication. The first factor is pH or degree of nira acidity which consists of 3 level (6.50 (± 0.10; 7.00 (± 0.10; 7.50 (± 0.10 and the second factor is addition of FCS concentration consisting of 3 level (5%; 10%; 15% (b/v. The analyzes used include analysis of organoleptic (color, aroma, taste as well as physical and chemical analyzes (sucrose content, moisture content, ash content, reducing sugar content, insoluble solid content. The analysis results of raw material showed that the pH of palm sap affect the amount of total sugar because the fermentation process. The addition of 10% FCS provides organoleptic results with the best reception at the brown crystal sugar. Physical and chemical test results of products with the best treatment showed that the levels of sucrose in brown crystal sugar was 81.483% in accordance with the minimum requirements specified Indonesian Industrial Standard (IIS, water content of 6.32% dry basis , ash content of 1.78%, reducing sugar amounted to 5.18%, and insoluble solid content of 0.089%.

Single-crystal growth of ceria-based materials

International Nuclear Information System (INIS)

Ulbrich, Gregor

2015-01-01

In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

(nBuCp)2ZrCl2-catalyzed Ethylene-4M1P Copolymerization: Copolymer Backbone Structure, Melt Behavior, and Crystallization

KAUST Repository

Atiqullah, Muhammad; Adamu, Sagir; Malaibari, Zuhair O.; Al-Harthi, Mamdouh A.; Emwas, Abdul-Hamid M.

2016-01-01

The judicious design of methylaluminoxane (MAO) anions expands the scope for developing industrial metallocene catalysts. Therefore, the effects of MAO anion design on the backbone structure, melt behavior, and crystallization of ethylene−4-methyl-1

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

Energy Technology Data Exchange (ETDEWEB)

Fan, Ya-Nan, E-mail: fanyn12@mails.tsinghua.edu.cn; Shi, Hui-Ji, E-mail: shihj@mail.tsinghua.edu.cn; Qiu, Wen-Hui

2015-09-17

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.

Growth of single crystals of BaFe12O19 by solid state crystal growth

Science.gov (United States)

Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

2016-10-01

Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

Research and Development of Crystal Purification for Product of Uranium Crystallization Process

Energy Technology Data Exchange (ETDEWEB)

Yano, K. [Japan Atomic Energy Agency - JAEA (Japan)

2009-06-15

Uranium crystallization has been developed as a part of advanced aqueous reprocessing for FBR spent fuel. Although the purity of uranyl nitrate hexahydrate (UNH) crystal from the crystallization process is supposed to meet a specification of FBR blanket fuel, an improvement of its purity is able to reduce the cost of fuel fabrication and storage (in case interim storage of recovered uranium is required). In this work, UNH crystal purification was developed as additional process after crystallization. Contamination of the crystal is caused by mother solution and solid state impurities. They are inseparable by washing and filtration. Mother solution on the surface of UNH crystals is removable by washing, but it is difficult to remove that in an obstructed part of crystalline aggregate by washing. Major elements of solid state impurities are cesium and barium. Cesium precipitates with tetravalent plutonium as a double nitrate, Cs{sub 2}Pu(NO{sub 3}){sub 6}. Barium crystallizes as Ba(NO{sub 3}){sub 2} because of its low solubility in nitric acid solution. It is difficult to separate their particle from UNH crystal by solid-liquid separation such as simple filtration. As a kind of crystal purification, there are some methods using sweating. Sweating is a phenomenon that a crystal melts partly below its melting point and it is caused by depression of freezing point due to impurity. It is considerably applicable for removal of mother solution. Concerning the solid state impurities, which has higher melting point than that of UNH crystal, it is supposed that they are separable by melting UNH crystal and filtration. The behaviors of impurities and applicability of sweating and melting-filtration operations to the purification for UNH crystal were investigated experimentally on a beaker and an engineering scale. With regard to behaviors of impurities, the conditions of cesium and barium precipitation were surveyed and it was clarified that there were most impurities on the

Time-dependent deformation of polymer network in polymer-stabilized cholesteric liquid crystals (Conference Presentation)

Science.gov (United States)

Lee, Kyung Min; Tondiglia, Vincent P.; Bunning, Timothy J.; White, Timothy J.

2017-02-01

Recently, we reported direct current (DC) field controllable electro-optic (EO) responses of negative dielectric anisotropy polymer stabilized cholesteric liquid crystals (PSCLCs). A potential mechanism is: Ions in the liquid crystal mixtures are trapped in/on the polymer network during the fast photopolymerization process, and the movement of ions by the application of the DC field distorts polymer network toward the negative electrode, inducing pitch variation through the cell thickness, i.e., pitch compression on the negative electrode side and pitch expansion on positive electrode side. As the DC voltage is directly applied to a target voltage, charged polymer network is deformed and the reflection band is tuned. Interestingly, the polymer network deforms further (red shift of reflection band) with time when constantly applied DC voltage, illustrating DC field induced time dependent deformation of polymer network (creep-like behavior). This time dependent reflection band changes in PSCLCs are investigated by varying the several factors, such as type and concentration of photoinitiators, liquid crystal monomer content, and curing condition (UV intensity and curing time). In addition, simple linear viscoelastic spring-dashpot models, such as 2-parameter Kelvin and 3-parameter linear models, are used to investigate the time-dependent viscoelastic behaviors of polymer networks in PSCLC.

Synthesis, crystallization behavior and surface modification of Ni-Cr-Si-Fe amorphous alloy

International Nuclear Information System (INIS)

Iqbal, M.; Akhter, J.I.; Rajput, M.U.; Mahmood, K.; Hussain, Z.; Hussain, S.; Rafiq, M.

2011-01-01

A quaternary Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ amorphous alloy was synthesized by melt spinning technique. Surface modification was done by electron beam melting (EBM), neutron irradiation and gamma-rays. Microstructure of as cast, annealed and modified samples was examined by scanning electron microscope. Crystallization behavior was studied by annealing the samples in vacuum at different temperatures in the range 773-1073 K. Techniques of X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for characterization. Differential scanning calorimetry (DSC) was conducted at various heating rates in the range 10-40 K/min. Thermal parameters like glass transition temperature T/sub g/, crystallization temperature T/sub x/, supercooled liquid region delta T/sub x/ and reduced glass transition temperature T/sub rg/ were measured. The Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ alloy exhibits wide supercooled liquid region of 60 K indicating good thermal stability. The activation energy was calculated to be 160 +- 4 kJ/mol using Kissinger and Ozawa equations respectively which indicates high resistance against crystallization. The XRD results of the samples annealed at 773 K, 923 K, 973 K and 1073 K/20 min show nucleation of Ni/sub 2/Cr/sub 3/ and NiCrFe crystalline phases. Vickers microhardness of the as cast ribbon was measured to be 680. About 30-50 % increase in hardness was achieved by applying EBM technique. (author)

Study of the fluorescence blinking behavior of single F2 color centers in LiF crystal

International Nuclear Information System (INIS)

Boichenko, S V; Koenig, K; Zilov, S A; Dresvianskiy, V P; Rakevich, A L; Kuznetsov, A V; Bartul, A V; Martynovich, E F; Voitovich, A P

2014-01-01

Using confocal fluorescence microscopy technique, we observed experimentally the luminescence of single F 2 color centers in LiF crystal. It is disclosed that the fluorescence shows blinking behavior. It is shown that this phenomenon is caused by the F 2 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

Cyberbullying behavior and adolescents' use of media with antisocial content: A cyclic process model

NARCIS (Netherlands)

den Hamer, A.H.; Konijn, E.A.; Keijer, M.G.

2014-01-01

The present study examined the role of media use in adolescents' cyberbullying behavior. Following previous research, we propose a Cyclic Process Model of face-to-face victimization and cyberbullying through two mediating processes of anger/frustration and antisocial media content. This model was

Micromechanical approach of the fatigue behavior in a superplastic single crystal

International Nuclear Information System (INIS)

Patoor, E.; Siredey, N.; Eberhardt, A.; Berveiller, M.

1995-01-01

Mechanical cycling of superelastic alloys leads to significant change in their observed behavior. Critical stress needed to induce the martensitic transformation is reduced while the tangent transformation modulus is increased. Microstructural observations have shown that a mechanical cycling produced a strongly oriented pattern of dislocations. This dislocation network is associated to an internal stress field. It seems reasonable to relate this internal stress field to the observed evolution of the mechanical response. This is phenomenologically performed in this work considering the thermodynamical potential associated to the martensitic transformation of a single crystal of parent phase in presence of a microstructure of defects. Evolutions of the microstructural state are defined using the volume fraction associated to the variant of martensite and additional volume fractions of defects related to the dislocation pattern. Results such obtained well-captured experimental observations. (orig.)

Effect of Fe2O3 on the crystallization behavior of glass-ceramics produced from naturally cooled yellow phosphorus furnace slag

Science.gov (United States)

Liu, Hong-pan; Huang, Xiao-feng; Ma, Li-ping; Chen, Dan-li; Shang, Zhi-biao; Jiang, Ming

2017-03-01

CaO-Al2O3-SiO2 (CAS) glass-ceramics were prepared via a melting method using naturally cooled yellow phosphorus furnace slag as the main raw material. The effects of the addition of Fe2O3 on the crystallization behavior and properties of the prepared glass-ceramics were studied by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The crystallization activation energy was calculated using the modified Johnson-Mehl-Avrami equation. The results show that the intrinsic nucleating agent in the yellow phosphorus furnace slag could effectively promote the crystallization of CAS. The crystallization activation energy first increased and then decreased with increasing amount of added Fe2O3. At 4wt% of added Fe2O3, the crystallization activation energy reached a maximum of 676.374 kJ·mol-1. The type of the main crystalline phase did not change with the amount of added Fe2O3. The primary and secondary crystalline phases were identified as wollastonite (CaSiO3) and hedenbergite (CaFe(Si2O6)), respectively.

Preparation of Three-Dimensional Photonic Crystals of Zirconia by Electrodeposition in a Colloidal Crystals Template

Directory of Open Access Journals (Sweden)

Lei Pan

2016-07-01

Full Text Available Three-dimensional photonic crystals of zirconia were prepared by electrodeposition in a colloidal crystals template following calcination at 500 °C. Scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and reflectance spectroscopy were employed to characterize the photonic crystals of zirconia. It was found that hydrated zirconium ions could penetrate the colloidal crystals template and reach the substrate easily by electrodeposition, which resulted in stronger bonding between the substrate and the as-deposited membrane. Moreover, the electrodeposited membrane had low water content, leading to a low amount of shrinkage during calcination. Both these properties could suppress detachment from the substrate upon removal of the colloidal crystals template. Therefore, the three-dimensional photonic crystals of zirconia synthesized in this study exhibited very good preservation of the ordered structures of the colloidal crystals template with a high density. A peak of reflection higher than 70% was formed in the reflectance spectrum because of the strong diffraction of the ordered structures.

Growth, structural and magnetic characterization of Al-substituted barium hexaferrite single crystals

International Nuclear Information System (INIS)

Vinnik, D.A.; Zherebtsov, D.A.; Mashkovtseva, L.S.; Nemrava, S.; Bischoff, M.; Perov, N.S.; Semisalova, A.S.; Krivtsov, I.V.; Isaenko, L.I.; Mikhailov, G.G.; Niewa, R.

2014-01-01

Highlights: • Growth of large Al-substituted crystals BaFe 12−x Al x O 19. • Al-content controllable by flux composition. • Crystallographic site preference of Al unraveled. • Magnetic characterization depending on Al-content. - Abstract: Large single crystals of aluminum-substituted M-type barium hexaferrite BaFe 12−x Al x O 19 were obtained from carbonate flux. The Al content in the crystals can be controlled via the Al content of the flux up to x = 1.1 according to single crystal X-ray structure refinements. Al shows a distinct preference to substitute Fe on crystallographic sites with high coordination numbers by oxygen atoms, whereas no significant amounts of Al can be found on a tetrahedrally coordinated site. An increasing amount of the aluminum dopant results in a monotonous reduction of the Curie temperature from 440 to 415 °C and the saturation magnetization at room temperature from 68 to 57 emu/g for single crystal and from 61 to 53 emu/g for powder samples

CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

KAUST Repository

Maculan, Giacomo; Sheikh, Arif D.; Abdelhady, Ahmed L.; Saidaminov, Makhsud I.; Haque, Mohammed; Banavoth, Murali; Alarousu, Erkki; Mohammed, Omar F.; Wu, Tao; Bakr, Osman

2015-01-01

a new method of sizeable CH3NH3PbCl3 single crystal growth based on retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge-carrier recombination and transport properties of single crystal

Acute isoproterenol induces anxiety-like behavior in rats and increases plasma content of extracellular vesicles.

Science.gov (United States)

Leo, Giuseppina; Guescini, Michele; Genedani, Susanna; Stocchi, Vilberto; Carone, Chiara; Filaferro, Monica; Sisti, Davide; Marcoli, Manuela; Maura, Guido; Cortelli, Pietro; Guidolin, Diego; Fuxe, Kjell; Agnati, Luigi Francesco

2015-04-01

Several clinical observations have demonstrated a link between heart rate and anxiety or panic disorders. In these patients, β-adrenergic receptor function was altered. This prompted us to investigate whether the β-adrenergic receptor agonist isoproterenol, at a dose that stimulates peripheral β-adrenergic system but has no effects at the central nervous system, can induce anxiety-like behavior in rats. Moreover, some possible messengers involved in the peripheral to brain communication were investigated. Our results showed that isoproterenol (5 mg kg(-1) i.p.) increased heart rate, evoked anxiety-like behavior, did not result in motor impairments and increased extracellular vesicle content in the blood. Plasma corticosterone level was unmodified as well as vesicular Hsp70 content. Vesicular miR-208 was also unmodified indicating a source of increased extracellular vesicles different from cardiomyocytes. We can hypothesize that peripheral extracellular vesicles might contribute to the β-adrenergic receptor-evoked anxiety-like behavior, acting as peripheral signals in modulating the mental state. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of Purification on the Crystallization of Lysozyme

Science.gov (United States)

Ewing, Felecia L.; Forsythe, Elizabeth L.; Van Der Woerd, Mark; Pusey, Marc L.

1996-01-01

We have additionally purified a commercial lysozyme preparation by cation exchange chromatography, followed by recrystallization. This material is 99.96% pure with respect to macromolecular impurities. At basic pH, the purified lysozyme gave only tetragonal crystals at 20 C. Protein used directly from the bottle, prepared by dialysis against distilled water, or which did not bind to the cation exchange column had considerably altered crystallization behavior. Lysozyme which did not bind to the cation exchange column was subsequently purified by size exclusion chromatography. This material gave predominately bundles of rod-shaped crystals with some small tetragonal crystals at lower pHs. The origin of the bundled rod habit was postulated to be a thermally dependent tetragonal- orthorhombic change in the protein structure. This was subsequently ruled out on the basis of crystallization behavior and growth rate experiments. This suggests that heterogeneous forms of lysozyme may be responsible. These results demonstrate three classes of impurities: (1) small molecules, which may be removed by dialysis; (2) macromolecules, which are removable by chromatographic techniques; and (3) heterogeneous forms of the protein, which can be removed in this case by cation exchange chromatography. Of these, heterogeneous forms of the lysozyme apparently have the greatest affect on its crystallization behavior.

Glass transition, crystallization kinetics and pressure effect on crystallization of ZrNbCuNiBe bulk metallic glass

DEFF Research Database (Denmark)

Xing, P.F.; Zhuang, Yanxin; Wang, W.H.

2002-01-01

The glass transition behavior and crystallization kinetics of Zr48Nb8Cu14Ni12Be18 bulk metallic glass have been investigated by differential scanning calorimetry and x-ray powder diffraction (XRD). The activation energies of both glass transition and crystallization events have been obtained using...... the Kissinger method. Results indicate that this glass crystallizes by a three-stage reaction: (1) phase separation and primary crystallization of glass, (2) formation of intermetallic compounds, and (3) decomposition of intermetallic compounds and crystallization of residual amorphous phase. The pressure...

Investigation of PEG crystallization in frozen PEG-sucrose-water solutions. I. Characterization of the nonequilibrium behavior during freeze-thawing.

Science.gov (United States)

Bhatnagar, Bakul S; Martin, Susan M; Teagarden, Dirk L; Shalaev, Evgenyi Y; Suryanarayanan, Raj

2010-06-01

Our objective was to characterize the nonequilibrium thermal behavior of frozen aqueous solutions containing PEG and sucrose. Aqueous solutions of (i) sucrose (10%, w/v) with different concentrations of PEG (1-20%, w/v), and (ii) PEG (10%, w/v) with different concentrations of sucrose (2-20%, w/v), were cooled to -70 degrees C at 5 degrees C/min and heated to 25 degrees C at 2 degrees C/min in a differential scanning calorimeter. Annealing was performed at temperatures ranging from -50 to -20 degrees C for 2 or 6 h. Similar experiments were also performed in the low-temperature stage of a powder X-ray diffractometer. A limited number of additional DSC experiments were performed wherein the samples were cooled to -100 degrees C. In unannealed systems with a fixed sucrose concentration (10%, w/v), the T'g decreased from -35 to -48 degrees C when PEG concentration was increased from 1% to 20% (w/v). On annealing at -25 degrees C, PEG crystallized. This was evident from the increase in T'g and the appearance of a secondary melting endotherm in the DSC. Low-temperature XRD provided direct evidence of PEG crystallization. Annealing at temperatures crystallization and a devitrification event was observed above the T'g. In unannealed systems with a fixed PEG concentration (10%, w/v), the T'g increased from -50 to -40 degrees C when sucrose concentration was increased from 5% to 50%, w/v. As the annealing time increased (at -25 degrees C), the T'g approached that of a sucrose-water system, reflecting progressive PEG crystallization. A second glass transition at approximately -65 degrees C was evident in unannealed systems [10%, w/v sucrose and 10 (or 20%), w/v PEG] cooled to -100 degrees C. Investigation of the nonequilibrium behavior of frozen PEG-sucrose-water ternary system revealed phase separation in the freeze-concentrate. Annealing facilitated PEG crystallization. (c) 2010 Wiley-Liss, Inc. and the American Pharmacists Association

The crystallization of (NiCu)ZrTiAlSi glass/crystalline composite

International Nuclear Information System (INIS)

Czeppe, T.; Sypien, A.; Ochin, P.; Anastassova, S.

2007-01-01

Alloys of composition (Ni 1-x Cu x ) 60 Zr 18 Ti 13 A1 5 Si 4 were investigated in the form of ribbons and massive samples. The microstructure of the massive samples consists of dendritic crystals in the amorphous or nanocrystalline matrix. The amount of the amorphous phase is the lowest in the sample with the highest Cu content. The segregation in the liquid phase, leading to the local differences in density and the composition of the crystallizing dendrites in the samples crystallized in the copper mould was shown. The typical compositions of the multi-component crystals could be distinguished; one with the increased content of aluminum, the second with the high content of silicon and third, with the high content of (NiCu) and (ZrTi). The cubic phase Ni(Cu)Ti(Zr) with Cu and Zr dissolved could be identified. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

The role of service-learning in college students' environmental literacy: Content knowledge, attitudes, and behaviors

Science.gov (United States)

Singletary, Joanna Lynn Bush

This study evaluated the relationship of environmental service-learning on environmental literacy in undergraduates. The subjects were 36 undergraduates at a small liberal arts university enrolled in an environmental biology course. To determine the role of environmental service-learning on college students' environmental knowledge, attitudes, behaviors, and environmental literacy, this study utilized concurrent mixed methods approach for qualitative and quantitative analysis. A quasi-experimental repeated measures approach was the design of the quantitative component of the study. Data were collected on attitude, behavior, and content knowledge aspects of environmental literacy as measured by the Environmental Literacy Survey (Kibert, 2000). Hypotheses were tested by independent samples ttests and repeated measures ANOVA. Repeated measures ANOVA conducted on participants' three subscales scores for the Environmental Literacy Survey (attitude, behavior, and knowledge) indicated that students who participated in environmental service-learning scored statistically significantly higher than those that did not initially participate in service-learning. Qualitative data collected in the form of journal reflections and portfolios were evaluated for themes of environmental attitudes or affective statements, environmentally positive behaviors and skills, and ecological content. Quantitative and qualitative data support the positive role of environmental service-learning in the development of environmental literacy in undergraduate students.

CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

Directory of Open Access Journals (Sweden)

A. NOZAD

2011-06-01

Full Text Available The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was bulk crystallization for base glass and the sample with addition of Li2O. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of Li2O was changed to the range of 317-322 KJ/mol.

Ductile–brittle behavior at blunted cavities in 3D iron crystals uncovered and covered by copper atoms

Czech Academy of Sciences Publication Activity Database

Pelikán, Vladimír; Hora, Petr; Červená, Olga; Spielmannová, Alena; Machová, Anna

2010-01-01

Roč. 4, č. 2 (2010), s. 191-200 ISSN 1802-680X R&D Projects: GA ČR(CZ) GA101/07/0789; GA AV ČR KJB200760802 Institutional research plan: CEZ:AV0Z20760514 Keywords : molecular dynamics * bcc iron crystal * blunted cavity * copper cover * ductile –brittle behavior Subject RIV: JG - Metallurgy http://www.kme.zcu.cz/acm/index.php/acm/article/view/48

Structure and crystallization behavior of La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} metaborate glasses doped with Nd{sup 3+} or Eu{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Pytalev, D.S., E-mail: pytalev@isan.troitsk.ru [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation); Caurant, D.; Majérus, O.; Trégouët, H. [Institut de Recherche de Chimie Paris, CNRS – Chimie ParisTech, 11 Rue Pierre et Marie Curie, 75005 Paris (France); Charpentier, T. [CEA, IRAMIS, NIMBE, CEA-CNRS UMR 3299, Laboratoire de Structure et Dynamique par Résonance Magnétique, 91191 Gif-sur-Yvette (France); Mavrin, B.N. [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation)

2015-08-25

Highlights: • The structure and crystallization behavior of the La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} glass are studied. • LaB{sub 3}O{sub 6} crystallizes congruently without intermediate but only from glass surface. • The structure of the amorphous and the crystalline phases differ significantly. • The activation energy of LaB{sub 3}O{sub 6} crystal growth is determined. - Abstract: The local structure and crystallization behavior of the stoichiometric La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} (LaMB) metaborate glass doped with Nd{sup 3+} or Eu{sup 3+} ions are studied using differential thermal analysis (DTA), X-ray diffraction (XRD), Raman scattering and {sup 11}B magic-angle spinning nuclear magnetic resonance (MAS NMR), optical absorbance and luminescence techniques. In the crystallized samples, XRD, NMR and Raman spectroscopy have detected the formation of only one crystalline phase (congruent crystallization of LaB{sub 3}O{sub 6}). No intermediate metastable crystalline phase has been detected before LaB{sub 3}O{sub 6} crystals formation (single stage crystallization process). The observation of heat treated glass samples by scanning electron microscopy (SEM) and optical microscopy coupled with the study of the effect of varying the glass particle size on the DTA curves have both revealed that LaB{sub 3}O{sub 6} crystallization only occurs by a heterogeneous nucleation mechanism (needle-shape crystals) from glass surface. The activation energy E{sub c} of crystal growth has been determined by performing DTA experiments at different heating rates with the Kissinger (784 kJ/mol) and Ozawa (801 kJ/mol) equations than can be used for surface crystallization processes. The heterogeneous crystallization behavior and the spectroscopic results obtained in this work by comparing the LaMB glass with the LaB{sub 3}O{sub 6} crystalline phase suggest the existence of significant structural differences between the amorphous and the crystalline phases contrary to what

Mitigating crystallization of saturated FAMEs (fatty acid methyl esters) in biodiesel: 2. The phase behavior of 2-stearoyl diolein–methyl stearate binary system

International Nuclear Information System (INIS)

Baker, Mark; Bouzidi, Laziz; Narine, Suresh S.

2015-01-01

The phase behavior of a model binary system made of OSO (2-stearoyl diolein) and MeS (methyl stearate) was investigated with differential scanning calorimetry and X-ray diffraction. The study is part of a series of investigations of unconventional additives such as TAGs (triacylglycerols) and dimers of TAGs with a demonstrated potential to significantly alter the crystallization of biodiesel. The TAG (triacylglycerol) was found to be effective in depressing the crystallization onset of the FAME (fatty acid methyl ester) significantly even at low concentration. OSO was shown to affect the crystallization of the mixtures strongly, and to dramatically alter their polymorphism. The system's phase diagram involved marked transformation lines including eutectics and solid–solid transitions. The molecular interactions were evaluated using a simple thermodynamic model. A mechanism for disruption of crystallization was proposed to be dependent on the peculiar geometry of OSO: the “straight” stearic acid participates easily in the lamellar packing of the equally “straight” FAME, whilst its kinked oleic acids effectively halt additional saturated FAMEs from participating due to steric hindrances. The findings of the study indicate that judicious loadings of TAGs which would target biodiesel's saturated FAMEs will have a substantial beneficial effect on the low temperature performance of the fuel. - Highlights: • 2-Steroyl diolein/methyl stearate (OSO/MeS) binary system investigated comprehensively. • OSO/MeS mixtures presented very complex phase trajectories and behavior. • OSO alters crystallization at both nucleation and growth stages profoundly. • Mechanism for disruption of crystallization proposed and verified. • OSO and homologues formulations can be effectives cold flow additives for biodiesel

Growth of single crystals of BaFe12O19 by solid state crystal growth

International Nuclear Information System (INIS)

Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

2016-01-01

Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

Electrical conductivity measurement on DKDP Crystals with different deuterated degrees

International Nuclear Information System (INIS)

Liu, Baoan; Yin, Xin; Xu, Mingxia; Ji, Shaohua; Zhu, Lili; Zhang, Lisong; Sun, Xun; Xu, Xinguang; Zhao, Minglei; Zhang, Qinghua

2012-01-01

Ten DKDP single crystals with deuterated degrees ranging from 0 to 90 % were grown by a rapid growth method. The electrical conductivities of these crystals were measured along a and c directions at room temperature. The electrical conductivity increases with the increase for deuterium content. Also, the electrical conductivities of certain crystals were measured at various temperatures ranging from 20 to 130 C. The values of activation energy decrease as the increase of deuterium content. The present study indicates that the deuterium tunneling frequency is smaller than that of hydrogen, which may be the reason why the variation of electrical conductivity happens after the substitution of hydrogen for deuterium in KDP crystal. (orig.)

Nucleation and crystal growth behavior of nepheline in simulated high-level waste glasses

Energy Technology Data Exchange (ETDEWEB)

Fox, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Amoroso, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Mcclane, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-26

The Savannah River National Laboratory (SRNL) has been tasked with supporting glass formulation development and process control strategies in key technical areas, relevant to the Department of Energy’s Office of River Protection (DOE-ORP) and related to high-level waste (HLW) vitrification at the Waste Treatment and Immobilization Plant (WTP). Of specific interest is the development of predictive models for crystallization of nepheline (NaAlSiO4) in HLW glasses formulated at high alumina concentrations. This report summarizes recent progress by researchers at SRNL towards developing a predicative tool for quantifying nepheline crystallization in HLW glass canisters using laboratory experiments. In this work, differential scanning calorimetry (DSC) was used to obtain the temperature regions over which nucleation and growth of nepheline occur in three simulated HLW glasses - two glasses representative of WTP projections and one glass representative of the Defense Waste Processing Facility (DWPF) product. The DWPF glass, which has been studied previously, was chosen as a reference composition and for comparison purposes. Complementary quantitative X-ray diffraction (XRD) and optical microscopy confirmed the validity of the methodology to determine nucleation and growth behavior as a function of temperature. The nepheline crystallization growth region was determined to generally extend from ~ 500 to >850 °C, with the maximum growth rates occurring between 600 and 700 °C. For select WTP glass compositions (high Al2O3 and B2O3), the nucleation range extended from ~ 450 to 600 °C, with the maximum nucleation rates occurring at ~ 530 °C. For the DWPF glass composition, the nucleation range extended from ~ 450 to 750 °C with the maximum nucleation rate occurring at ~ 640 °C. The nepheline growth at the peak temperature, as determined by XRD, was between 35 - 75 wt.% /hour. A maximum nepheline growth rate of ~ 0.1 mm/hour at 700 °C was measured for the DWPF

Nucleation and crystal growth behavior of nepheline in simulated high-level waste glasses

International Nuclear Information System (INIS)

Fox, K.; Amoroso, J.; Mcclane, D.

2017-01-01

The Savannah River National Laboratory (SRNL) has been tasked with supporting glass formulation development and process control strategies in key technical areas, relevant to the Department of Energy's Office of River Protection (DOE-ORP) and related to high-level waste (HLW) vitrification at the Waste Treatment and Immobilization Plant (WTP). Of specific interest is the development of predictive models for crystallization of nepheline (NaAlSiO4) in HLW glasses formulated at high alumina concentrations. This report summarizes recent progress by researchers at SRNL towards developing a predicative tool for quantifying nepheline crystallization in HLW glass canisters using laboratory experiments. In this work, differential scanning calorimetry (DSC) was used to obtain the temperature regions over which nucleation and growth of nepheline occur in three simulated HLW glasses - two glasses representative of WTP projections and one glass representative of the Defense Waste Processing Facility (DWPF) product. The DWPF glass, which has been studied previously, was chosen as a reference composition and for comparison purposes. Complementary quantitative X-ray diffraction (XRD) and optical microscopy confirmed the validity of the methodology to determine nucleation and growth behavior as a function of temperature. The nepheline crystallization growth region was determined to generally extend from ~ 500 to >850 °C, with the maximum growth rates occurring between 600 and 700 °C. For select WTP glass compositions (high Al2O3 and B2O3), the nucleation range extended from ~ 450 to 600 °C, with the maximum nucleation rates occurring at ~ 530 °C. For the DWPF glass composition, the nucleation range extended from ~ 450 to 750 °C with the maximum nucleation rate occurring at ~ 640 °C. The nepheline growth at the peak temperature, as determined by XRD, was between 35 - 75 wt.% /hour. A maximum nepheline growth rate of ~ 0.1 mm/hour at 700 °C was measured for the DWPF

Crystallization and melting behavior of poly(ethylene oxide) and its blend with styrene-based ionomer using time-resolved SAXS/WAXS experiments

Energy Technology Data Exchange (ETDEWEB)

Slusarczyk, CzesLaw, E-mail: cslusarczyk@ath.bielsko.pl [Institute of Textile Engineering and Polymer Materials, University of Bielsko-BiaLa, ul. Willowa 2, 43-309 Bielsko-BiaLa (Poland)

2011-10-15

Time-resolved synchrotron wide- and small-angle X-ray scattering experiments were used to investigate the crystallization behavior and microstructure development of neat poly(ethylene oxide) (PEO) and its 50/50 blend with ionomer containing 6.4 mol% of sodium acrylate. The apparent lateral crystal sizes D{sub (120)} and D{sub (112)/(004)} were derived from the WAXS profiles. It was found that D{sub (120)} and D{sub (112)/(004)} of PEO in the blend are almost independent of temperature and are smaller when compared to those of neat PEO sample. The evolution of morphological parameters extracted from time-resolved SAXS profiles such as the long period L, the lamellar crystal thickness l{sub C} and the amorphous layer thickness l{sub A}, shows that the crystallization process of neat PEO follows the nucleation theory. The lamellar crystal thickness l{sub C} shows a single linear dependence on inverse supercooling, over the whole temperature range investigated. In contrast, the crystallization process of PEO in the blend (i.e. in the presence of interactions with the ionomer) follows the nucleation theory only in the narrow supercooling range. It was found also that the morphology of the blend consists of a broad population of lamellar crystal thicknesses. During heating lamellae melt in the reversed sequence of their formation.

Parental mediation of media messages does matter: more interaction about objectionable content is associated with emerging adults' sexual attitudes and behaviors.

Science.gov (United States)

Radanielina-Hita, Marie Louise

2015-01-01

An online survey of undergraduates explored the effects of recalled parent-child interaction regarding media on their critical thinking skills, beliefs about alcohol and sex, and current reports of attitudes and risky sexual behaviors. Students from a northwestern university completed the questionnaire three times during the fall of 2011. Effective parental mediation was found to be a protective factor against the negative effects of objectionable content on sexual attitudes and behaviors through its effect on critical thinking toward media content and expectancies. Participants whose parents critiqued media portrayals reported a higher level of critical thinking. More critical orientation toward media decreased the effects of objectionable content on expectancies and sexual behaviors. On the other hand, participants whose parents endorsed media portrayals reported lower levels of critical thinking. Developing critical thinking toward media is an effective approach to helping young people make good decisions about their health. Although viewers' understanding of media content may be biased by the emotional aspect of decision making, critical thinking was shown to decrease the appeal of mediated messages on behaviors. Parents play an important role in developing children's critical thinking skills, and those who mediate their children's media use can establish behaviors that will prove beneficial to their children later in life.

Crystal structure, thermal behavior, vibrational spectroscopy and ...

Indian Academy of Sciences (India)

64

A single crystal was carefully selected under polarizing microscope and .... properties of our compound using infrared absorption and Raman scattering. ... pics in Raman at 1762 and 1782 cm-1 are assigned to the δ(HOH) mode of the water ...

Liquid crystal dimers

CERN Document Server

Kumar Pal, Santanu

2017-01-01

This book covers in-depth discussion of design principles, synthesis and thermal behavior of all types of liquid crystal (LC) dimers. The text presents recent advances in the field of LC dimers consisting of different mesogenic units such as calamitic, discotic and bent-core molecules. It starts with a chapter on the introduction of liquid crystal dimers, including their odd-even behavior, basic classification of dimers and common mesophases in dimers. The text shows how the molecular architectures are being used to develop new materials to study a range of interesting phenomena such as the biaxial nematic phase containing rod-like and disc-like mesogenic units. Finally, the text presents perspectives related to technological relevance of these dimers such as dopants in LC display mixtures exhibiting faster relaxation time, strong flexoelectric coupling and others to effect control over the properties of these materials.

On the behavior of water at subfreezing temperatures in a protein crystal: evidence of higher mobility than in bulk water.

Science.gov (United States)

Wang, Dongqi; Böckmann, Anja; Dolenc, Jožica; Meier, Beat H; van Gunsteren, Wilfred F

2013-10-03

NMR experiments have shown that water molecules in the crystal of the protein Crh are still mobile at temperatures well below 273 K. In order to investigate this water anomaly, a molecular dynamics (MD) simulation study of crystalline Crh was carried out to determine the mobility of water in this crystal. The simulations were carried out at three temperatures, 150, 200, and 291 K. Simulations of bulk water at these temperatures were also done to obtain the properties of the simple point charge (SPC) water model used at these temperatures and to allow a comparison of the properties of water in the Crh crystal with those of bulk water at the same temperatures. According to the simulations, water is immobilized at 150 K both in crystal and in bulk water. As expected, at 291 K it diffuses and rotates more slowly in the protein crystal than in bulk water. However, at 200 K, the translational and rotational mobility of the water molecules is larger in the crystal than in bulk water. The enhancement of water mobility in the crystal at 200 K was further investigated by MD simulations in which the backbone or all protein atoms were positionally restrained, and in which additionally the electrostatic protein-water interactions were removed. Of these changes in the environment of the water molecules, rigidifying the protein backbones slightly enhanced water diffusion, while it slowed down rotation. In contrast, removal of electrostatic protein-water interactions did not change water diffusion but enhanced rotational motion significantly. Further investigations are required to delineate particular features of the protein crystal that induce the anomalous behavior of water at 200 K.

Gallium arsenide single crystal solar cell structure and method of making

Science.gov (United States)

Stirn, Richard J. (Inventor)

1983-01-01

A production method and structure for a thin-film GaAs crystal for a solar cell on a single-crystal silicon substrate (10) comprising the steps of growing a single-crystal interlayer (12) of material having a closer match in lattice and thermal expansion with single-crystal GaAs than the single-crystal silicon of the substrate, and epitaxially growing a single-crystal film (14) on the interlayer. The material of the interlayer may be germanium or graded germanium-silicon alloy, with low germanium content at the silicon substrate interface, and high germanium content at the upper surface. The surface of the interface layer (12) is annealed for recrystallization by a pulsed beam of energy (laser or electron) prior to growing the interlayer. The solar cell structure may be grown as a single-crystal n.sup.+ /p shallow homojunction film or as a p/n or n/p junction film. A Ga(Al)AS heteroface film may be grown over the GaAs film.

Random photonic crystal optical memory

International Nuclear Information System (INIS)

Wirth Lima Jr, A; Sombra, A S B

2012-01-01

Currently, optical cross-connects working on wavelength division multiplexing systems are based on optical fiber delay lines buffering. We designed and analyzed a novel photonic crystal optical memory, which replaces the fiber delay lines of the current optical cross-connect buffer. Optical buffering systems based on random photonic crystal optical memory have similar behavior to the electronic buffering systems based on electronic RAM memory. In this paper, we show that OXCs working with optical buffering based on random photonic crystal optical memories provides better performance than the current optical cross-connects. (paper)

Crystal structure, growth and nonlinear optical studies of isonicotinamide p-nitrophenol: A new organic crystal for optical limiting applications

Science.gov (United States)

Vijayalakshmi, A.; Vidyavathy, B.; Vinitha, G.

2016-08-01

Isonicotinamide p-nitrophenol (ICPNP), a new organic material, was synthesized using methanol solvent. Single crystals of ICPNP were grown using a slow evaporation solution growth technique. Crystal structure of ICPNP is elucidated by single crystal X-ray diffraction analysis. It belongs to monoclinic crystal system with space group of P21/c. It forms two dimensional networks by O-H…O, N-H…O and C-H…O hydrogen bonds. The molecular structure of ICPNP was further confirmed by Fourier transform infrared (FTIR) spectral analysis. The optical transmittance range and the lower cut-off wavelength (421 nm) with the optical band gap (2.90 eV) of the ICPNP crystal were determined by UV-vis-NIR spectral study. Thermal behavior of ICPNP was studied by thermo gravimetric and differential thermal analyses (TG/DTA). The relative dielectric permittivity was calculated for various temperature ranges. Laser damage threshold of ICPNP crystal was found to be 1.9 GW/cm2 using an Nd:YAG laser. A Z-scan technique was employed to measure the nonlinear absorption coefficient, nonlinear refractive index and nonlinear optical susceptibility. Optical limiting behavior of ICPNP was observed at 35 mW input power.

Affect, Behavior, Cognition, and Desire in the Big Five: An Analysis of Item Content and Structure

Science.gov (United States)

Wilt, Joshua; Revelle, William

2015-01-01

Personality psychology is concerned with affect (A), behavior (B), cognition (C) and desire (D), and personality traits have been defined conceptually as abstractions used to either explain or summarize coherent ABC (and sometimes D) patterns over time and space. However, this conceptual definition of traits has not been reflected in their operationalization, possibly resulting in theoretical and practical limitations to current trait inventories. Thus, the goal of this project was to determine the affective, behavioral, cognitive and desire (ABCD) components of Big-Five personality traits. The first study assessed the ABCD content of items measuring Big-Five traits in order to determine the ABCD composition of traits and identify items measuring relatively high amounts of only one ABCD content. The second study examined the correlational structure of scales constructed from items assessing ABCD content via a large, web-based study. An assessment of Big-Five traits that delineates ABCD components of each trait is presented, and the discussion focuses on how this assessment builds upon current approaches of assessing personality. PMID:26279606

The influence of sol on the behavior of melting and nonisothermal crystallization kinetic of radiation cross-linking HDPE

International Nuclear Information System (INIS)

Deng Pengyang; Xie Hongfeng; Deng Mingxiao; Zhong Xiaoguang

2000-01-01

By using DSC, the behavior of second melting and nonisothermal crystallization of pure gel pure sol and sol-gel blend of radiation crosslinking HDPE was studied. The authors found that, because of the existence of sol, there is notable difference between pure gel and pure sol or sol-gel blend. Under the same dose, the melting point and crystallization temperature of pure sol and sol-gel blend are higher than that of pure gel. At the same time, the authors also found that the Avrami exponent of original PE, pure sol and sol-gel blend is the similar to each other and different to that of pure gel, which means that the procedure of nucleation and growth of these samples is the same and also different to that of pure gel

Influence of nickel and beryllium content on swelling behavior of copper irradiated with fast neutrons

Energy Technology Data Exchange (ETDEWEB)

Singh, B.N.; Garner, F.A.; Edwards, D.J. [Pacific Northwest National Lab., Richland, WA (United States); Evans, J.H.

1996-10-01

In the 1970`s, the effects of nickel content on the evolution of dislocation microstructures and the formation and growth of voids in Cu-Ni alloys were studied using 1 MeV electrons in a high voltage electron microscope. The swelling rate was found to decrease rapidly with increasing nickel content. The decrease in the swelling rate was associated with a decreasing void growth rate with increasing nickel content at irradiation temperatures up to 450{degrees}C. At 500{degrees}C, both void size and swelling rate were found to peak at 1 and 2% Ni, respectively, and then to decrease rapidly with increasing nickel content. However, recent work has demonstrated that the swelling behavior of Cu-5%Ni irradiated with fission neutrons is very similar for that of pure copper. The present experiments were designed to investigate this apparent discrepancy.

Liquid Crystal Colloids

Science.gov (United States)

Smalyukh, Ivan I.

2018-03-01

Colloids are abundant in nature, science, and technology, with examples ranging from milk to quantum dots and the colloidal atom paradigm. Similarly, liquid crystal ordering is important in contexts ranging from biological membranes to laboratory models of cosmic strings and liquid crystal displays in consumer devices. Some of the most exciting recent developments in both of these soft matter fields emerge at their interface, in the fast-growing research arena of liquid crystal colloids. Mesoscale self-assembly in such systems may lead to artificial materials and to structures with emergent physical behavior arising from patterning of molecular order and nano- or microparticles into precisely controlled configurations. Liquid crystal colloids show exceptional promise for new discovery that may impinge on composite material fabrication, low-dimensional topology, photonics, and so on. Starting from physical underpinnings, I review the state of the art in this fast-growing field, with a focus on its scientific and technological potential.

Dielectric behavior of MgO:Li+ crystals

International Nuclear Information System (INIS)

Puma, M.; Lorincz, A.; Andrews, J.F.; Crawford, J.H Jr.

1980-01-01

Measurements of the dielectric constant in crystals of MgO doped with Li + ions have been carried out after quenching from anneals at 1300 0 C in static air. Prior to heat treatment the crystals showed no discernible dielectric loss but afterwards the loss tangent exceeded 0.4. For 10 min anneals the dielectric relaxation is very close to a Debye process and the temperature dependence of the maximum of the loss peak corresponds to an activation energy of 0.72 eV. When plotted in the form of a Cole-Cole arc the data indicate that deviation from a Debye relaxation amounts to a distribution of relaxation time no greater than that which can be accounted for with a distribution of activation energies only 0.007 eV. For longer heating times overlapping relaxation processes appear. The lack of broadening of the loss peak and the magnitude of the relaxation time yield clues as to possible loss mechanisms

Dielectric behavior of MgO:Li+ crystals

International Nuclear Information System (INIS)

Puma, M.; Lorincz, A.; Andrews, J.F.; Crawford, J.H. Jr.

1982-01-01

Measurements of the dielectric constant in crystals of MgO doped with Li + ions have been carried out after quenching from anneals at 1300 0 C in static air. Prior to heat treatment, the crystals showed no discernible dielectric loss, but afterwards, the loss tangent exceeded 0.4. For 10-min anneals, the dielectric relaxation is very close to a Debye process, and the temperature dependence of the maximum of the loss peak corresponds to an activation energy of 0.724 eV. When plotted in the form of a Cole-Cole arc, the data indicate that deviation from a Debye relaxation amounts to a distribution of relaxation time no greater than that which can be accounted for with a distribution of activation energies of only 0.007 eV. For longer heating times, overlapping relaxation processes appear. The lack of broadening of the loss peak, and the magnitude of the relaxation time, yield clues as to possible loss mechanisms

Prevalence of behavior changing strategies in fitness video games: theory-based content analysis.

Science.gov (United States)

Lyons, Elizabeth Jane; Hatkevich, Claire

2013-05-07

Fitness video games are popular, but little is known about their content. Because many contain interactive tools that mimic behavioral strategies from weight loss intervention programs, it is possible that differences in content could affect player physical activity and/or weight outcomes. There is a need for a better understanding of what behavioral strategies are currently available in fitness games and how they are implemented. The purpose of this study was to investigate the prevalence of evidence-based behavioral strategies across fitness video games available for home use. Games available for consoles that used camera-based controllers were also contrasted with games available for a console that used handheld motion controllers. Fitness games (N=18) available for three home consoles were systematically identified and play-tested by 2 trained coders for at least 3 hours each. In cases of multiple games from one series, only the most recently released game was included. The Sony PlayStation 3 and Microsoft Xbox360 were the two camera-based consoles, and the Nintendo Wii was the handheld motion controller console. A coding list based on a taxonomy of behavioral strategies was used to begin coding. Codes were refined in an iterative process based on data found during play-testing. The most prevalent behavioral strategies were modeling (17/18), specific performance feedback (17/18), reinforcement (16/18), caloric expenditure feedback (15/18), and guided practice (15/18). All games included some kind of feedback on performance accuracy, exercise frequency, and/or fitness progress. Action planning (scheduling future workouts) was the least prevalent of the included strategies (4/18). Twelve games included some kind of social integration, with nine of them providing options for real-time multiplayer sessions. Only two games did not feature any kind of reward. Games for the camera-based consoles (mean 12.89, SD 2.71) included a greater number of strategies than those

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.

Synergistic promotion of polar phase crystallization of PVDF by ionic liquid with PEG segment

Science.gov (United States)

Xu, Pei; Fu, Weijia; Cui, Zhaopei; Ding, Yunsheng

2018-06-01

To investigate the effect of imidazolium ionic liquid with poly(ethylene glycol) segment (IL) on the polar phase crystallization behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites were prepared using solution-cast method. The crystallization peak temperature of PVDF composites and the growth speed of samples decrease with increasing of IL. The >CF2 groups in amorphous region are retained and >CF2 groups in crystalline region are liberated by the PEG long soft segments of IL. The intensity of peaks represented as α phase reduces, moreover polar phase content increases with increasing of IL. The interaction between the >CF2 and the imidazolium cation can induce the polar phase, and the interaction between the >CF2 and PEG soft segment can strengthen polar crystalline induction. PVDF/12IL composite can form big γ spherulite circled by β phase.

Downstream Processability of Crystal Habit-Modified Active Pharmaceutical Ingredient

DEFF Research Database (Denmark)

Pudasaini, Nawin; Upadhyay, Pratik Pankaj; Parker, Christian Richard

2017-01-01

Efficient downstream processing of active pharmaceutical ingredients (APIs) can depend strongly on their particulate properties, such as size and shape distributions. Especially in drug products with high API content, needle-like crystal habit of an API may show compromised flowability and tablet......Efficient downstream processing of active pharmaceutical ingredients (APIs) can depend strongly on their particulate properties, such as size and shape distributions. Especially in drug products with high API content, needle-like crystal habit of an API may show compromised flowability...

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.

Behavior of an epoxy-polysulfide adhesive in wood joints exposed to moisture content changes

Science.gov (United States)

Gordon P. Krueger

1965-01-01

The mechanical behavior of a flexible epoxy-resin adhesive system was observed in joints of plywood to lumber. The joints were subjected to internal swelling stresses caused by an increase in moisture content. Previous experimental work at the U.S. Forest Products Laboratory has shown that this adhesive system acts as a strain-absorbing cushion and thus has a...

Unintentional Exposure to Online Sexual Content and Sexual Behavior Intentions Among College Students in China.

Science.gov (United States)

Zhang, Jingwen; Jemmott, John B

2015-07-01

This study examined the relations of unintentional exposure to Internet sexual content to intentions for sex and condom use and potential mediators of these relations, including attitudes, norms, and self-efficacy, among college students in China. A sample of 524 Chinese college students completed an online questionnaire. Mediation path analyses were conducted to test the theory of planned behavior as a model of the relations between unintentional exposure and intentions to have sex and use condoms. On average, students reported being unintentionally exposed to Internet sexual content about 3 to 4 times during the past month. Unintentional exposure was indirectly associated with intention to have sex, mediated through descriptive and injunctive norms. Descriptive norm was a stronger mediator for females than males. In contrast, unintentional exposure was unrelated to condom-use intention and mediators. The theory of planned behavior provides a model for the development of Internet-based interventions with these students. © 2014 APJPH.

The Effects of Dietary Fat and Iron Interaction on Brain Regional Iron Contents and Stereotypical Behaviors in Male C57BL/6J Mice

Directory of Open Access Journals (Sweden)

Lumei Liu

2016-07-01

Full Text Available Adequate brain iron levels are essential for enzyme activities, myelination, and neurotransmitter synthesis in the brain. Although systemic iron deficiency has been found in genetically or dietary-induced obese subjects, the effects of obesity-associated iron dysregulation in brain regions have not been examined. The objective of this study was to examine the effect of dietary fat and iron interaction on brain regional iron contents and regional-associated behavior patterns in a mouse model. Thirty C57BL/6J male weanling mice were randomly assigned to six dietary treatment groups (n=5 with varying fat (control/high and iron (control/high/low contents. The stereotypical behaviors were measured during the 24th week. Blood, liver, and brain tissues were collected at the end of the 24th week. Brains were dissected into the hippocampus, midbrain, striatum, and thalamus regions. Iron contents and ferritin-H (FtH protein and mRNA expressions in these regions were measured. Correlations between stereotypical behaviors and brain regional iron contents were analyzed at the 5% significance level. Results showed that high-fat diet altered the stereotypical behaviors such as inactivity and total distance traveled (P<0.05. The high-fat diet altered brain iron contents and ferritin-H (FtH protein and mRNA expressions in a regional-specific manner: 1 high-fat diet significantly decreased the brain iron content in the striatum (P<0.05, but not other regions; and 2 thalamus has a more distinct change in FtH mRNA expression compared to other regions. Furthermore, high-fat diet resulted in a significant decreased total distance traveled and a significant correlation between iron content and sleeping in midbrain (P<0.05. Dietary iron also decreased brain iron content and FtH protein expression in a regionally specific manner. The effect of interaction between dietary fat and iron was observed in brain iron content and behaviors. All these findings will lay

Role of organoclay in controlling the morphology and crystal-growth behavior of biodegradable polymer-blend thin films studied using atomic force microscopy

CSIR Research Space (South Africa)

Malwela, T

2014-09-01

Full Text Available clays, their organic modifications and their initial d(sub001)-spacing on the morphology and crystal growth behavior of the PLA/PBSA blend were studied. An atomic force microscopy equipped with a hot-stage scanner was used to examine the crystalline...

Effects of crystallization on structural and dielectric properties of thin amorphous films of (1 - x)BaTiO3-xSrTiO3 (x=0-0.5, 1.0)

Science.gov (United States)

Kawano, H.; Morii, K.; Nakayama, Y.

1993-05-01

The possibilities for fabricating solid solutions of (Ba1-x,Srx)TiO3 (x≤0.5,1.0) by crystallization of amorphous films and for improving their dielectric properties by adjusting the Sr content were investigated. Thin amorphous films were prepared from powder targets consisting of mixtures of BaTiO3 and SrTiO3 by sputtering with a neutralized Ar-ion beam. The amorphous films crystallized into (Ba1-x, Srx)TiO3 solid solutions with a cubic perovskite-type structure after annealing in air at 923 K for more than 1 h. The Debye-type dielectric relaxation was observed for the amorphous films, whereas the crystallized films showed paraelectric behavior. The relative dielectric constants were of the order of 20 for the amorphous samples, but increased greatly after crystallization to about 60-200, depending on the composition; a larger increase in the dielectric constant was observed in the higher Sr content films, in the range x≤0.5, which could be correlated with an increase in the grain size of the crystallites. The crystallization processes responsible for the difference in the grain size are discussed based on the microstructural observations.

Optical and scintillating properties of Ce:Li(Y,Lu)F4 single crystals

International Nuclear Information System (INIS)

Yokota, Yuui; Kurosawa, Shunsuke; Chani, Valery; Kamada, Kei; Yoshikawa, Akira

2014-01-01

We have investigated the optical and scintillating properties of Lu co-doped Ce:LiYF 4 single crystals with various Lu content. In the transmittance and absorption spectra, the absorption peaks at 243 nm get systematically red shifted in contrast to the peaks at 197 and 200 nm which get blue shifted with the increase in Lu content. At the same time, emission peaks at 306 nm and 200 nm under 295 nm excitation also get red shifted. The decay time of Ce:Li(Y,Lu)F 4 crystals under 295 nm excitation is found to be faster than that of Ce:LiYF 4 and Ce:LiLuF 4 crystals. The alpha-peak positions in the pulse-height spectra and decay times of crystals under alpha-ray irradiation are found to vary with the Lu content. - Highlights: • Optical and scintillation properties of Ce:Li(Y 1-x Lu x )F 4 crystals were inspected. • Increase of Lu content resulted change of the position of four absorption peaks. • Admixing of Y and Lu decreased the light yield and increased the decay time. • The Ce:LiLuF 4 crystal indicated the largest light yield in the pulse-height spectra. • Li[(Y 0.8 Lu 0.2 ) 0.98 Ce 0.02 ]F 4 indicated larger light yield than Ce:LiYF 4 crystal

Crystallization of copper metaphosphate glass

Science.gov (United States)

Bae, Byeong-Soo; Weinberg, Michael C.

1993-01-01

The effect of the valence state of copper in copper metaphosphate glass on the crystallization behavior and glass transition temperature has been investigated. The crystallization of copper metaphosphate is initiated from the surface and its main crystalline phase is copper metaphosphate (Cu(PO)3),independent of the (Cu sup 2+)/(Cu(total)). However, the crystal morphology, the relative crystallization rates, and their temperature dependences are affected by the (Cu sup 2+)/(Cu (total)) ratio in the glass. On the other hand, the totally oxidized glass crystallizes from all over the surface. The relative crystallization rate of the reduced glass to the totally oxidized glass is large at low temperature, but small at high temperature. The glass transition temperature of the glass increases as the (Cu sup 2+)/(Cu(total)) ratio is raised. It is also found that the atmosphere used during heat treatment does not influence the crystallization of the reduced glass, except for the formation of a very thin CuO surface layer when heated in air.

Improvement of seawater salt quality by hydro-extraction and re-crystallization methods

Science.gov (United States)

Sumada, K.; Dewati, R.; Suprihatin

2018-01-01

Indonesia is one of the salt producing countries that use sea water as a source of raw materials, the quality of salt produced is influenced by the quality of sea water. The resulting average salt quality contains 85-90% NaCl. The Indonesian National Standard (SNI) for human salt’s consumption sodium chloride content is 94.7 % (dry base) and for industrial salt 98,5 %. In this study developed the re-crystallization without chemical and hydro-extraction method. The objective of this research to choose the best methods based on efficiency. The results showed that re-crystallization method can produce salt with NaCl content 99,21%, while hydro-extraction method content 99,34 % NaCl. The salt produced through both methods can be used as a consumption and industrial salt, Hydro-extraction method is more efficient than re-crystallization method because re-crystallization method requires heat energy.

Crystallization of Ulex europaeus lectin I.

Science.gov (United States)

Vandonselaar, M; Delbaere, L T

1994-10-21

The lectin I from Ulex europaeus (UEAI) has a strong affinity for the H-type 2 human blood group determinant. Single crystals of UEAI have been grown in the monoclinic crystal system. Initial crystals were obtained after 11 months from a solution of 10 mg/ml protein, 40% 2,4-methylpentanediol and 0.1 N acetate buffer at pH 5.2. The technique of washing and reseeding was used to generate large suitable crystals. The space group is C2 with a = 78.84 A, b = 69.85 A, c = 120.62 A, beta = 108.74 degrees and Z = 4; there is one molecular dimer per asymmetric unit and the solvent content is estimated to be 58%. The crystals diffract to at least 2.8 A d spacings and are stable in the X-ray beam for more than three days.

Crystallization of Na2O-SiO2 gel and glass

Science.gov (United States)

Neilson, G. F.; Weinberg, M. C.

1984-01-01

The crystallization behavior of a 19 wt pct soda silica gel and gel-derived glass was compared to that of the ordinary glass of the same composition. Both bulk and ground glass samples were utilized. X-ray diffraction measurements were made to identify the crystalline phases and gauge the extent of crystallization. It was found that the gel crystallized in a distinctive manner, while the gel glass behavior was not qualitatively different from that of the ordinary glass.

Growth of binary solid solution single crystals and calculation of melt surface displacement velocity

International Nuclear Information System (INIS)

Agamaliyev, Z.A.; Tahirov, V.I.; Hasanov, Z.Y.; Quliyev, A.F.

2007-01-01

A binary solid solution single crystal growth method has been worked out. Cylinder feeding alloy with complex content distribution and truncated cone crucible are used. Second component distribution coefficient is more than unit. Content distribution along grown crystal is found by solving continuity equation. After reaching dynamic equilibrium state second component concentration in grown crystal is saturated the value of which is less than the average ona in the feeding alloy. Using the method Ge-Si perfect single crystals has been grown. Calculation method of melt surface displacement velocity has been offered as well

RETRACTED: Nucleation and growth behavior of well-aligned ZnO nanorods on organic substrates in aqueous solutions

Science.gov (United States)

Lin, Chin-Ching; Chen, San-Yuan; Cheng, Syh-Yuh

2005-09-01

Available online : 21 July 2005 This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Two papers published in the Journal of Crystal Growth are being retracted due to a case of misrepresentation and reuse of data. A reader of the Journal has brought to our attention the reuse of data within two published papers: Growth behavior and microstructure evolution of ZnO nanorods grown on Si in aqueous solution, Sz-Chian Liou, Chi-Sheng Hsiao, San-Yuan Chen, Journal of Crystal Growth 274 (2005) 438-446. DOI: 10.1016/j.jcrysgro.2004.10.025 Nucleation and growth behavior of well-aligned ZnO nanorods on organic substrates in aqueous solutions, Chin-Ching Lin, San-Yuan Chen, and Syh-Yuh Cheng, Journal of Crystal Growth 283 (2005) 141-146. DOI: 10.1016/j.jcrysgro.2005.05.065 In these papers the same transmission electron micrograph was used to describe two different experimental situations and results bringing into question the content of these papers. The reuse of data without proper attribution is not acceptable within the scientific publishing community. In the present case, this is compounded by the attribution of the micrograph to a different experimental situation and drawing , as a result, new conclusions from data obtained from different samples. Such behavior undermines the integrity of the scientific publishing endeavor and is not acceptable. The authors are responsible for the content of their papers.

Effect of irradiation on differential thermal properties and crystallization behavior of some lithium borate glasses

International Nuclear Information System (INIS)

El-Alaily, N.A.; Mohamed, R.M.

2001-01-01

Differential thermal properties and the crystallization behavior of binary system Li 2 O-B 2 O 3 glasses were investigated. The effects of the presence of oxides of aluminum, lead or one of the transition metals TiO 2 or V 2 O 5 or Fe 2 O 3 in the parent glass were also studied. The effects of three different heat treatments on the crystalline structure of all the studied glasses were also investigated. The results showed that all glass samples were amorphous before the heat treatment, with the most common formed phase being tetraborate Li 2 B 8 O 13 (Li 2 O-4B 2 O 3 ). The exposure of the glass samples to either gamma rays or fast neutrons resulted in considerable changes in their thermal behavior. The results also showed that T g increases for all studied glasses when subjected to irradiation either by fast neutron or gamma rays, while T c decreased only at higher doses

Micro-mechanical investigation of the effect of fine content on mechanical behavior of gap graded granular materials using DEM

Directory of Open Access Journals (Sweden)

Taha Habib

2017-01-01

Full Text Available In this paper, we present a micro-mechanical study of the effect of fine content on the behavior of gap graded granular samples by using numerical simulations performed with the Discrete Element Method. Different samples with fine content varied from 0% to 30% are simulated. The role of fine content in reinforcing the granular skeleton and in supporting the external deviatoric stress is then brought into the light.

Butterfly wing color: A photonic crystal demonstration

Science.gov (United States)

Proietti Zaccaria, Remo

2016-01-01

We have theoretically modeled the optical behavior of a natural occurring photonic crystal, as defined by the geometrical characteristics of the Teinopalpus Imperialis butterfly. In particular, following a genetic algorithm approach, we demonstrate how its wings follow a triclinic crystal geometry with a tetrahedron unit base. By performing both photonic band analysis and transmission/reflection simulations, we are able to explain the characteristic colors emerging by the butterfly wings, thus confirming their crystal form.

Brilliance and flux reduction in imperfect inclined crystals

International Nuclear Information System (INIS)

Lee, W.K.; Blasdell, R.C.; Fernandez, P.B.; Macrander, A.T.; Mills, D.M.

1996-01-01

The inclined crystal geometry has been suggested as a method of reducing the surface absorbed power density of high-heat-load monochromators for third-generation synchrotron radiation sources. Computer simulations have shown that if the crystals are perfectly aligned and have no strains then the diffraction properties of a pair of inclined crystals are very similar to a pair of conventional flat crystals with only subtle effects differentiating the two configurations. However, if the crystals are strained, these subtle differences in the behavior of inclined crystals can result in large beam divergences causing brilliance and flux losses. This manuscript elaborates on these issues and estimates potential brilliance and flux losses from strained inclined crystals at the APS

Reshock and release response of aluminum single crystal

International Nuclear Information System (INIS)

Huang, H.; Asay, J. R.

2007-01-01

Reshock and release experiments were performed on single crystal aluminum along three orientations and on polycrystalline 1050 aluminum with 50 μm grain size at shock stresses of 13 and 21 GPa to investigate the mechanisms for previously observed quasielastic recompression behavior. Particle velocity profiles obtained during reshocking both single crystals and polycrystalline aluminum from initial shock stresses of 13-21 GPa show similar quasielastic recompression behavior. Quasielastic release response is also observed in all single crystals, but the magnitude of the effect is crystal orientation dependent, with [111] and [110] exhibiting more ideal elastic-plastic release for unloading from the shocked state than for the [100] orientation and polycrystalline aluminum. The quasielastic response of 1050 aluminum is intermediate to that of the [100] and [111] orientations. Comparison of the wave profiles obtained for both unloading and reloading of single crystals and polycrystalline 1050 aluminum from shocked states suggests that the observed quasielastic response of polycrystalline aluminum results from the averaging response of single crystals for shock propagation along different orientations, and that the response of 1050 aluminum with large grain boundaries is not significantly different from the results obtained on single crystal aluminum. The yield strength of the single crystals and 1050 aluminum is found to increase with shock stress, which is consistent with previous results [H. Huang and I. R. Asay, J. Appl. Phys. 98, 033524 (2005)

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Directory of Open Access Journals (Sweden)

Angeliki Lekatou

2016-02-01

Full Text Available Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.% Co were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co to coarse primary Al9Co2 predominance (20 wt.% Co. Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al9Co2, the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified.

Tobacco, alcohol, and other risk behaviors in film: how well do MPAA ratings distinguish content?

Science.gov (United States)

Tickle, Jennifer J; Beach, Michael L; Dalton, Madeline A

2009-12-01

To evaluate the usefulness of Motion Picture Association of America (MPAA) ratings for parental selection of appropriate films for children, the 100 top grossing movies each year from 1996 through 2004 (N = 900) were content analyzed to measure risk behaviors in each film. More restrictive MPAA ratings (R and PG-13) were associated with increased mean seconds of portrayals of tobacco use, alcohol use, and sexual content; increased frequency of violent content; and increased salience of drug use. MPAA ratings, however, did not clearly distinguish films based on tobacco or alcohol use. Fifty percent of R-rated movies contained 124 seconds or more of tobacco use, comparable with 26% of PG-13 and 17% of PG movies. Fifty percent of R-rated movies contained 162 seconds or more of alcohol use, comparable with 49% of PG-13 and 25% of PG movies. Because of the high degree of overlap in alcohol and tobacco content between rating categories, the MPAA rating system, as currently defined, is not adequate for parents who wish to limit their children's exposure to tobacco or alcohol content in movies.

Sub-threshold investigation of two coupled photonic crystal cavities

DEFF Research Database (Denmark)

Schubert, Martin; Frandsen, Lars Hagedorn; Skovgård, Troels Suhr

2009-01-01

The behavior of two coupled photonic crystal membrane cavities with quantum dots separated by different number of holes is investigated. The measured spectral splitting with increased coupling is verified by 3D calculations and discussed.......The behavior of two coupled photonic crystal membrane cavities with quantum dots separated by different number of holes is investigated. The measured spectral splitting with increased coupling is verified by 3D calculations and discussed....

Investigation of organic desulfurization additives affecting the calcium sulfate crystals formation

Directory of Open Access Journals (Sweden)

Lv Lina

2017-01-01

Full Text Available In the study, the optimal experimental conditions for gypsum crystals formation were 323 K, 300 rpm stirring speed. The major impurities of Mg2+, Al3+ and Fe3+ were found to inhibit calcium sulfate crystals formation. Fe3+ caused the strongest inhibition, followed by Mg2+ and Al3+. The influence of desulfurization additives on the gypsum crystals formation was explored with the properties of moisture content, particle size distribution and crystal morphology. The organic desulfurization additives of adipic acid, citric acid, sodium citrate and benzoic acid were investigated. Citric acid and sodium citrate were found to improve the quality of gypsum. Moisture contents were reduced by more than 50%, gypsum particle sizes were respectively enlarged by 9.1 and 22.8%, induction time extended from 4.3 (blank to 5.3 and 7.8 min, and crystal morphology trended to be thicker.

Effect of niobium content and austenizing temperature on the fracture behavior of Niocor 2 stell

International Nuclear Information System (INIS)

Teixeira, J.C.G.; Darwish, F.A.I.

1981-01-01

The effect of the austenizing temperature on the fracture behavior of Niocor 2 steel of two different Nb contents was studied by means of instrumented impact testing. It was observed that the toughness of the hot rolled steel could be improved by an austenizing treatment at 920 0 C followed by cooling in air. In that respect the steel with the higher Nb content was shown to be slightly superior to the one with the lower content. For higher austenizing temperatures the toughness exhibited a considerable drop over a certain temperature range. This fall in toughness is explained in terms of the segregation of embrittling related to species to the grain boundary area, as related to the grain growth that takes place at high austenizing temperatures. (Author) [pt

Phenomenon of ''self-cleaning'' of crystals

International Nuclear Information System (INIS)

Matveev, O.A.; Arkad'eva, E.N.; Goncharov, L.A.

1975-01-01

Crystals of germanium and cadmium telluride have been produced having the characteristics corresponding to the low content of electrically active impurities and crystal defects. The crystals have been grown under conditions of an equilibrium diffusion-concentration interaction of the impurities and crystal defects, with the donor alloying and controlling the acceptors concentration. These crystals have been studied with the help of the mass-spectral analysis, the Hall effect, photoelectroscopy, spectral photoconductivity and losses of collection of a charge from an ionizing particle on gamma-detectors fabricated of the crystals. Herein the doped composition of the crystals has been determined, the concentrations of the shallow and deep acceptors and donors have been measured separately, the life-times of the electrons and holes have been measured, the energetic position and the concentration of the carrier capture levels have been determined. The crystals grown possess all the characteristic features of rather pure crystals. The results of the mass-spectral analysis have shown that in the cadmium telluride crystals the impurities are present within 10 14 to 10 17 cm -3 . Therefore, a deep ''self-refining'' of the crystal takes place, which proceeds by means of deactivation of the electrically active centers with their associating into electrically inactive complexes. Thus a fact of the deep ''self-refining'' of germanium- and cadmium telluride crystals is stated. It is presumed that such a ''self-refining'' can actually proceed practically in all the crystals

Investigation of the liquid crystal alignment layer: effect on electrical properties

International Nuclear Information System (INIS)

Abderrahmen, Asma; Romdhane, Fayda Fekih; Gharbi, Abdelhafidh; Ouada, Hafedh Ben

2008-01-01

We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit

Investigation of the liquid crystal alignment layer: effect on electrical properties

Energy Technology Data Exchange (ETDEWEB)

Abderrahmen, Asma; Romdhane, Fayda Fekih; Gharbi, Abdelhafidh [Laboratoire de la matiere molle, Faculte des sciences, Tunis (Tunisia); Ouada, Hafedh Ben [Laboratoire de physique et chimie des interfaces, Faculte des sciences, 5000 Monastir (Tunisia)], E-mail: asma_abderrahmen@yahoo.fr

2008-04-01

We investigate the electrical behavior of a symmetric liquid crystal (LC) cell: elecrode-silane-LC-silane-electrode. The silane (chlorodimethyloctadecyl-silane) layer induces a homeotropic orientation of the nematic liquid crystal (NLC) molecules. The wettability technique is used to detect the change of the surface energy of the electrode upon cleaning and silane layer deposition. We report on the dynamic impedance measurements of the nematic liquid crystal cell. It is found that the silane alignment layer has a blocking effect on the liquid crystal (LC) cell. We also study the relaxation behavior of the cell which is later assimilated as an electrical equivalent circuit.

Crystallization kinetics of amorphous aluminum-tungsten thin films

Energy Technology Data Exchange (ETDEWEB)

Car, T.; Radic, N. [Rugjer Boskovic Inst., Zagreb (Croatia). Div. of Mater. Sci.; Ivkov, J. [Institute of Physics, Bijenicka 46, P.O.B. 304, HR-10000 Zagreb (Croatia); Babic, E.; Tonejc, A. [Faculty of Sciences, Physics Department, Bijenicka 32, P.O.B. 162, HR-10000 Zagreb (Croatia)

1999-01-01

Crystallization kinetics of the amorphous Al-W thin films under non-isothermal conditions was examined by continuous in situ electrical resistance measurements in vacuum. The estimated crystallization temperature of amorphous films in the composition series of the Al{sub 82}W{sub 18} to Al{sub 62}W{sub 38} compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined. The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled process, whereas in films with the composition similar to the stoichiometric compound (Al{sub 4}W), the interface-controlled crystallization probably occurred. (orig.) With 4 figs., 1 tab., 26 refs.

Effect of sintering temperature and boron carbide content on the wear behavior of hot pressed diamond cutting segments

Directory of Open Access Journals (Sweden)

Islak S.

2015-01-01

Full Text Available The aim of this study was to investigate the effect of sintering temperature and boron carbide content on wear behavior of diamond cutting segments. For this purpose, the segments contained 2, 5 and 10 wt.% B4C were prepared by hot pressing process carried out under a pressure of 35 MPa, at 600, 650 and 700 °C for 3 minutes. The transverse rupture strength (TRS of the segments was assessed using a three-point bending test. Ankara andesite stone was cut to examine the wear behavior of segments with boron carbide. Microstructure, surfaces of wear and fracture of segments were determined by scanning electron microscopy (SEM-EDS, and X-ray diffraction (XRD analysis. As a result, the wear rate decreased significantly in the 0-5 wt.% B4C contents, while it increased in the 5-10 wt.% B4C contents. With increase in sintering temperature, the wear rate decreased due to the hard matrix.

Prevalence of Behavior Changing Strategies in Fitness Video Games: Theory-Based Content Analysis

Science.gov (United States)

Hatkevich, Claire

2013-01-01

Background Fitness video games are popular, but little is known about their content. Because many contain interactive tools that mimic behavioral strategies from weight loss intervention programs, it is possible that differences in content could affect player physical activity and/or weight outcomes. There is a need for a better understanding of what behavioral strategies are currently available in fitness games and how they are implemented. Objective The purpose of this study was to investigate the prevalence of evidence-based behavioral strategies across fitness video games available for home use. Games available for consoles that used camera-based controllers were also contrasted with games available for a console that used handheld motion controllers. Methods Fitness games (N=18) available for three home consoles were systematically identified and play-tested by 2 trained coders for at least 3 hours each. In cases of multiple games from one series, only the most recently released game was included. The Sony PlayStation 3 and Microsoft Xbox360 were the two camera-based consoles, and the Nintendo Wii was the handheld motion controller console. A coding list based on a taxonomy of behavioral strategies was used to begin coding. Codes were refined in an iterative process based on data found during play-testing. Results The most prevalent behavioral strategies were modeling (17/18), specific performance feedback (17/18), reinforcement (16/18), caloric expenditure feedback (15/18), and guided practice (15/18). All games included some kind of feedback on performance accuracy, exercise frequency, and/or fitness progress. Action planning (scheduling future workouts) was the least prevalent of the included strategies (4/18). Twelve games included some kind of social integration, with nine of them providing options for real-time multiplayer sessions. Only two games did not feature any kind of reward. Games for the camera-based consoles (mean 12.89, SD 2.71) included a

Tobacco and alcohol use behaviors portrayed in music videos: a content analysis.

Science.gov (United States)

DuRant, R H; Rome, E S; Rich, M; Allred, E; Emans, S J; Woods, E R

1997-07-01

Music videos from five genres of music were analyzed for portrayals of tobacco and alcohol use and for portrayals of such behaviors in conjunction with sexuality. Music videos (n = 518) were recorded during randomly selected days and times from four television networks. Four female and four male observers aged 17 to 24 years were trained to use a standardized content analysis instrument. All videos were observed by rotating two-person, male-female teams who were required to reach agreement on each behavior that was scored. Music genre and network differences in behaviors were analyzed with chi-squared tests. A higher percentage (25.7%) of MTV videos than other network videos portrayed tobacco use. The percentage of videos showing alcohol use was similar on all four networks. In videos that portrayed tobacco and alcohol use, the lead performer was most often the one smoking or drinking and the use of alcohol was associated with a high degree of sexuality on all the videos. These data indicate that even modest levels of viewing may result in substantial exposure to glamorized depictions of alcohol and tobacco use and alcohol use coupled with sexuality.

Stress Management Apps With Regard to Emotion-Focused Coping and Behavior Change Techniques: A Content Analysis.

Science.gov (United States)

Christmann, Corinna Anna; Hoffmann, Alexandra; Bleser, Gabriele

2017-02-23

Chronic stress has been shown to be associated with disease. This link is not only direct but also indirect through harmful health behavior such as smoking or changing eating habits. The recent mHealth trend offers a new and promising approach to support the adoption and maintenance of appropriate stress management techniques. However, only few studies have dealt with the inclusion of evidence-based content within stress management apps for mobile phones. The aim of this study was to evaluate stress management apps on the basis of a new taxonomy of effective emotion-focused stress management techniques and an established taxonomy of behavior change techniques. Two trained and independent raters evaluated 62 free apps found in Google Play with regard to 26 behavior change and 15 emotion-focused stress management techniques in October 2015. The apps included an average of 4.3 behavior change techniques (SD 4.2) and 2.8 emotion-focused stress management techniques (SD 2.6). The behavior change technique score and stress management technique score were highly correlated (r=.82, P=.01). The broad variation of different stress management strategies found in this sample of apps goes in line with those found in conventional stress management interventions and self-help literature. Moreover, this study provided a first step toward more detailed and standardized taxonomies, which can be used to investigate evidence-based content in stress management interventions and enable greater comparability between different intervention types. ©Corinna Anna Christmann, Alexandra Hoffmann, Gabriele Bleser. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 23.02.2017.

Crystal growth and scintillation properties of multi-component oxide single crystals: Ce:GGAG and Ce:La-GPS

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, A., E-mail: yoshikawa@imr.tohoku.ac.jp [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kamada, K. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Kurosawa, S. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Shoji, Y. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); C& A Corporation, 6-6-40 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Yokota, Y. [New Industry Creation Hatchery Center (NICHe), Tohoku University, Sendai 980-8579 (Japan); Chani, V.I. [Institute for Materials Research (IMR), Tohoku University, Sendai 980-8577 (Japan); Nikl, M. [Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic)

2016-01-15

Crystal growth by micro-pulling-down, Czochralski, and floating zone methods and scintillation properties of Ce:Gd{sub 3}(Ga,Al){sub 5}O{sub 12} (Ce:GGAG) multi-component oxide garnets, and Ce:Gd{sub 2}Si{sub 2}O{sub 7} (Ce:GPS) or Ce:(La,Gd){sub 2}Si{sub 2}O{sub 7} (Ce:La-GPS) pyro-silicates are reviewed. GGAG crystals demonstrated practically linear dependences of some of the parameters including lattice constant, emission wavelength, and band gap on Ga content. However, emission intensity, light yield and energy resolution showed maxima for intermediate compositions. GGAG crystals had the highest light yield of 56,000 photon/MeV for Ga content of 2.7 atoms per garnet formula unit. Similarly the light yield and energy resolution of La-GPS showed the highest values of 40,000 photon/MeV and 4.4%@662 keV, respectively, for La-GPS containing 10% of La. Moreover, La-GPS demonstrated stable scintillation performance up to 200 °C.

Draft Tube Baffle (DTB) crystallizers: A study of stationary and dynamically behaving Crystal Size Distributions (CSD)

Science.gov (United States)

Deleer, B. G. M.

1981-11-01

Based on population balance, CSD behavior as a function of geometrical and operating variables was studied, using a crystallizer. A potash alum-water system, involving a separation technique which uses surface active agents and an apolar, organic liquid to separate potash alum crystals from mother liquid under the influence of gravity was used to check experimental findings against literature data. Results show action of annular settling spaces is strongly influenced by fluid velocities perpendicular to those directed upwards. The well-mixed volume decreases with increasing crystallizer size until a minimum effective volume is reached. As supersaturation is constant throughout the crystallizer volume under stationary operating conditions, the annular settling space behaves like a growth chamber for crystals in its volume. Swirl in the lower part of the annular volume introduces significant back mixing. Crystals within this space either grow and return to the well-mixed part, or withdraw from the annular volume permanently.

Effect of γ-radiation on crystallization of polycaprolactone

International Nuclear Information System (INIS)

Zhu Guangming; Xu, Qianyong; Qin Ruifeng; Yan Hongxia; Liang Guozheng

2005-01-01

The crystallization behavior of radiation cross-linked poly(ε-caprolactone) (PCL) was studied by DSC at different cooling rates. The crystallization process was analyzed by the Ozawa equation and the Mo-Zhishen method that is developed from combining the Avrami equation and the Ozawa equation. It was concluded that the crystallization of radiation crosslinked PCL is governed by heterogeneous nucleation and single-dimension growth; the crystal fraction and rates of crystallization are related to the radiation dose and degree of cross-linking; the relationship between relative crystallinity and time follows the Ozawa equation: The higher the degree of crosslinking, the less the crystal velocity constant. The activation energy of crystallization for irradiated PCL is between 65 and 54kJ/mol

Dramatic Improvement of Crystal Quality for Low-temperature-grown Rabbit Muscle Aldolase

Energy Technology Data Exchange (ETDEWEB)

Park, H.; Rangarajan, E; Sygusch, J; Izard, T

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 {angstrom} Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase.

Science.gov (United States)

Park, Hajeung; Rangarajan, Erumbi S; Sygusch, Jurgen; Izard, Tina

2010-05-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA-LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 A Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA-LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice.

Numerical study of slip system activity and crystal lattice rotation under wedge nanoindents in tungsten single crystals

Science.gov (United States)

Volz, T.; Schwaiger, R.; Wang, J.; Weygand, S. M.

2018-05-01

Tungsten is a promising material for plasma facing components in future nuclear fusion reactors. In the present work, we numerically investigate the deformation behavior of unirradiated tungsten (a body-centered cubic (bcc) single crystal) underneath nanoindents. A finite element (FE) model is presented to simulate wedge indentation. Crystal plasticity finite element (CPFE) simulations were performed for face-centered and body-centered single crystals accounting for the slip system family {110} in the bcc crystal system and the {111} slip family in the fcc system. The 90° wedge indenter was aligned parallel to the [1 ¯01 ]-direction and indented the crystal in the [0 1 ¯0 ]-direction up to a maximum indentation depth of 2 µm. In both, the fcc and bcc single crystals, the activity of slip systems was investigated and compared. Good agreement with the results from former investigations on fcc single crystals was observed. Furthermore, the in-plane lattice rotation in the material underneath an indent was determined and compared for the fcc and bcc single crystals.

Crystallization of Trehalose in Frozen Solutions and its Phase Behavior during Drying

Energy Technology Data Exchange (ETDEWEB)

Sundaramurthi, Prakash; Patapoff, Thomas W.; Suryanarayanan, Raj (Genentech); (UMM)

2015-02-19

To study the crystallization of trehalose in frozen solutions and to understand the phase transitions during the entire freeze-drying cycle. Aqueous trehalose solution was cooled to -40 C in a custom-designed sample holder. The frozen solution was warmed to -18 C and annealed, and then dried in the sample chamber of the diffractometer. XRD patterns were continuously collected during cooling, annealing and drying. After cooling, hexagonal ice was the only crystalline phase observed. However, upon annealing, crystallization of trehalose dihydrate was evident. Seeding the frozen solution accelerated the solute crystallization. Thus, phase separation of the lyoprotectant was observed in frozen solutions. During drying, dehydration of trehalose dihydrate yielded a substantially amorphous anhydrous trehalose. Crystallization of trehalose, as trehalose dihydrate, was observed in frozen solutions. The dehydration of the crystalline trehalose dihydrate to substantially amorphous anhydrate occurred during drying. Therefore, analyzing the final lyophile will not reveal crystallization of the lyoprotectant during freeze-drying. The lyoprotectant crystallization can only become evident by continuous monitoring of the system during the entire freeze-drying cycle. In light of the phase separation of trehalose in frozen solutions, its ability to serve as a lyoprotectant warrants further investigation.

CH3NH3PbCl3 Single Crystals: Inverse Temperature Crystallization and Visible-Blind UV-Photodetector

KAUST Repository

Maculan, Giacomo

2015-09-02

Single crystals of hybrid perovskites have shown remarkably improved physical properties compared to their polycrystalline film counterparts, underscoring their importance in the further development of advanced semiconductor devices. Here we present a new method of sizeable CH3NH3PbCl3 single crystal growth based on retrograde solubility behavior of hybrid perovskites. We show, for the first time, the energy band structure, charge-carrier recombination and transport properties of single crystal CH3NH3PbCl3. The chloride-based perovskite crystals exhibit trap-state density, charge carriers concentration, mobility and diffusion length comparable with the best quality crystals of methylammonium lead iodide or bromide perovskites reported so far. The high quality of the crystal along with its suitable optical bandgap enabled us to design and build an efficient visible-blind UV-photodetector, demonstrating the potential of this material to be employed in optoelectronic applications.

Evaluation of radar reflectivity factor simulations of ice crystal populations from in situ observations for the retrieval of condensed water content in tropical mesoscale convective systems

Directory of Open Access Journals (Sweden)

E. Fontaine

2017-06-01

Full Text Available This study presents the evaluation of a technique to estimate cloud condensed water content (CWC in tropical convection from airborne cloud radar reflectivity factors at 94 GHz and in situ measurements of particle size distributions (PSDs and aspect ratios of ice crystal populations. The approach is to calculate from each 5 s mean PSD and flight-level reflectivity the variability of all possible solutions of m(D relationships fulfilling the condition that the simulated radar reflectivity factor (T-matrix method matches the measured radar reflectivity factor. For the reflectivity simulations, ice crystals were approximated as oblate spheroids, without using a priori assumptions on the mass–size relationship of ice crystals. The CWC calculations demonstrate that individual CWC values are in the range ±32 % of the retrieved average CWC value over all CWC solutions for the chosen 5 s time intervals. In addition, during the airborne field campaign performed out of Darwin in 2014, as part of the international High Altitude Ice Crystals/High Ice Water Content (HAIC/HIWC projects, CWCs were measured independently with the new IKP-2 (isokinetic evaporator probe instrument along with simultaneous particle imagery and radar reflectivity. Retrieved CWCs from the T-matrix radar reflectivity simulations are on average 16 % higher than the direct CWCIKP measurements. The differences between the CWCIKP and averaged retrieved CWCs are found to be primarily a function of the total number concentration of ice crystals. Consequently, a correction term is applied (as a function of total number concentration that significantly improves the retrieved CWC. After correction, the retrieved CWCs have a median relative error with respect to measured values of only −1 %. Uncertainties in the measurements of total concentration of hydrometeors are investigated in order to calculate their contribution to the relative error of calculated CWC with respect to

Effect of Ultrasonic Nano-Crystal Surface Modification (UNSM) on the Passivation Behavior of Aged 316L Stainless Steel.

Science.gov (United States)

Kim, Ki-Tae; Lee, Jung-Hee; Kim, Young-Sik

2017-06-27

Stainless steels have good corrosion resistance in many environments but welding or aging can decrease their resistance. This work focused on the effect of aging time and ultrasonic nano-crystal surface modification on the passivation behavior of 316L stainless steel. In the case of slightly sensitized 316L stainless steel, increasing the aging time drastically decreased the pitting potential, increased the passive current density, and decreased the resistance of the passive film, even though aging did not form chromium carbide and a chromium depletion zone. This behavior is due to the micro-galvanic corrosion between the matrix and carbon segregated area, and this shows the importance of carbon segregation in grain boundaries to the pitting corrosion resistance of stainless steel, in addition to the formation of the chromium depletion zone. UNSM (Ultrasonic Nano Crystal Surface Modification)-treatment to the slightly sensitized 316L stainless steel increased the pitting potential, decreased the passive current density, and increased the resistance of the passive film. However, in the case of heavily sensitized 316L stainless steel, UNSM-treatment decreased the pitting potential, increased the passive current density, and decreased the resistance of the passive film. This behavior is due to the dual effects of the UNSM-treatment. That is, the UNSM-treatment reduced the carbon segregation, regardless of whether the stainless steel 316L was slightly or heavily sensitized. However, since this treatment made mechanical flaws in the outer surface in the case of the heavily sensitized stainless steel, UNSM-treatment may eliminate chromium carbide, and this flaw can be a pitting initiation site, and therefore decrease the pitting corrosion resistance.

Crystal plasticity study of single crystal tungsten by indentation tests

International Nuclear Information System (INIS)

Yao, Weizhi

2012-01-01

Owing to its favorable material properties, tungsten (W) has been studied as a plasma-facing material in fusion reactors. Experiments on W heating in plasma sources and electron beam facilities have shown an intense micro-crack formation at the heated surface and sub-surface. The cracks go deep inside the irradiated sample, and often large distorted areas caused by local plastic deformation are present around the cracks. To interpret the crack-induced microscopic damage evolution process in W, one needs firstly to understand its plasticity on a single grain level, which is referred to as crystal plasticity. In this thesis, the crystal plasticity of single crystal tungsten (SCW) has been studied by spherical and Berkovich indentation tests and the finite element method with a crystal plasticity model. Appropriate values of the material parameters included in the crystal plasticity model are determined by fitting measured load-displacement curves and pile-up profiles with simulated counterparts for spherical indentation. The numerical simulations reveal excellent agreement with experiment. While the load-displacement curves and the deduced indentation hardness exhibit little sensitivity to the indented plane at small indentation depths, the orientation of slip directions within the crystals governs the development of deformation hillocks at the surface. It is found that several factors like friction, indentation depth, active slip systems, misoriented crystal orientation, misoriented sample surface and azimuthal orientation of the indenter can affect the indentation behavior of SCW. The Berkovich indentation test was also used to study the crystal plasticity of SCW after deuterium irradiation. The critical load (pop-in load) for triggering plastic deformation under the indenter is found to depend on the crystallographic orientation. The pop-in loads decrease dramatically after deuterium plasma irradiation for all three investigated crystallographic planes.

Composition dependence of spontaneous crystallization of phosphosilicate glass melts during cooling

DEFF Research Database (Denmark)

Liu, S.J.; Zhu, C.F.; Zhang, Y.F.

2012-01-01

Crystallization behavior of alumino-phospho-silicate melts during cooling is studied by means of the differential scanning calorimetry, X-ray diffractometry and viscometry. The results show a pronounced impact of alkaline earth oxide, alkali oxide and fluoride on the crystal type and crystallizat......Crystallization behavior of alumino-phospho-silicate melts during cooling is studied by means of the differential scanning calorimetry, X-ray diffractometry and viscometry. The results show a pronounced impact of alkaline earth oxide, alkali oxide and fluoride on the crystal type...... and crystallization degree. It is found that adding NaF into the studied compositions slightly decreases melt fragility and improves both the glass-forming ability and melt workability. This effect is associated with the unique structural role of NaF compared to the other modifier oxides. It is also found...

Annealing behavior of solution grown polyethylene single crystals

NARCIS (Netherlands)

Loos, J.; Tian, M.

2006-01-01

The morphology evolution of solution grown polyethylene single crystals has been studied upon annealing below their melting temperature by using atomic force microscopy (AFM). AFM investigations have been performed ex situ, which means AFM investigations at room temperature after the annealing

Composition and crystallization kinetics of R2O-Al2O3-SiO2 glass-ceramics

International Nuclear Information System (INIS)

Xiong, Dehua; Cheng, Jinshu; Li, Hong

2010-01-01

The crystallization behavior and microstructure of R 2 O-Al 2 O 3 -SiO 2 (R means K, Na and Li) glass were investigated by means of differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The crystallization kinetic parameters including the crystallization apparent activation energy (E a ), the Avrami parameter (n), glass transition temperature (T g ) and the activity energy of glass transition (E t ) were also measured with different methods. The results have shown that: the DSC traces of composition A parent glass have two different precipitation crystallization peaks corresponding to E a1 (A) = 151.4 kJ/mol (Li 2 SiO 3 ) and E a2 (A) = 623.1 kJ/mol (Li 2 Si 2 O 5 ), the average value of n = 1.70 (Li 2 Si 2 O 5 ) for the surface crystallization and E t (A) = 202.8 kJ/mol. And E a (B) = 50.7 kJ/mol (Li 2 SiO 3 ), the average value of n = 3.89 (Li 2 SiO 3 ) for the bulk crystallization and E t (B) = 220.4 kJ/mol for the composition B parent glass. Because of the content of R 2 O is bigger than composition A, composition B parent glass has a lower E a , T g and a larger n, E t .

Molecular Weight and Crystallization Temperature Effects on Poly(ethylene terephthalate (PET Homopolymers, an Isothermal Crystallization Analysis

Directory of Open Access Journals (Sweden)

Leonardo A. Baldenegro-Perez

2014-02-01

Full Text Available The isothermal crystallization of poly(ethylene terephthalate (PET homopolymers with different molecular weight was studied in a wide temperature range (140–230 °C using different experimental techniques. Three different morphological regions, labeled r1, r2 and r3, were distinguished as a function of crystallization temperature (Tc. In r1 (low Tc crystallized samples were characterized by a low crystalline degree with a small spherulite texture containing thin crystals. In r2 (intermediate Tc samples showed medium size spherulites composed of two distinct crystalline families (thin and thick crystals. In this temperature range, the crystallization exhibited a maximum value and it was associated with a high content of secondary crystals. In r3 (high Tc, samples presented considerable amorphous zones and regions consisting of oversized spherulites containing only thick crystals. Time-resolved wide-angle X-ray diffraction measurements, using synchrotron radiation, indicated a rapid evolution of the crystalline degree within the second region, in contrast with the quite slow evolution observed in the third region. On the other hand, by small-angle X-ray scattering (SAXS and time-resolved SAXS experiment, it was found that the long period (L as well as the lamellar thickness (lc increase as a function of Tc, corroborating the formation of the thickest crystals in the third region. From all these observations, a morphological model was proposed for each region.

The high-pressure behavior of spherocobaltite (CoCO3): a single crystal Raman spectroscopy and XRD study

Science.gov (United States)

Chariton, Stella; Cerantola, Valerio; Ismailova, Leyla; Bykova, Elena; Bykov, Maxim; Kupenko, Ilya; McCammon, Catherine; Dubrovinsky, Leonid

2018-01-01

Magnesite (MgCO3), calcite (CaCO3), dolomite [(Ca, Mg)CO3], and siderite (FeCO3) are among the best-studied carbonate minerals at high pressures and temperatures. Although they all exhibit the calcite-type structure ({R}\\bar{3}{c}) at ambient conditions, they display very different behavior at mantle pressures. To broaden the knowledge of the high-pressure crystal chemistry of carbonates, we studied spherocobaltite (CoCO3), which contains Co2+ with cation radius in between those of Ca2+ and Mg2+ in calcite and magnesite, respectively. We synthesized single crystals of pure spherocobaltite and studied them using Raman spectroscopy and X-ray diffraction in diamond anvil cells at pressures to over 55 GPa. Based on single crystal diffraction data, we found that the bulk modulus of spherocobaltite is 128 (2) GPa and K' = 4.28 (17). CoCO3 is stable in the calcite-type structure up to at least 56 GPa and 1200 K. At 57 GPa and after laser heating above 2000 K, CoCO3 partially decomposes and forms CoO. In comparison to previously studied carbonates, our results suggest that at lower mantle conditions carbonates can be stable in the calcite-type structure if the radius of the incorporated cation(s) is equal or smaller than that of Co2+ (i.e., 0.745 Å).

Growth and characterization of 2-Methylimidazolium D-tartrate single crystal

Science.gov (United States)

Srinivasan, T. P.; Anandhi, S.; Gopalakrishnan, R.

2011-03-01

Single crystal of 2-Methylimidazolium D-tartrate (2MImdT; C8N2O6H12) has been grown by slow evaporation solution growth technique at room temperature using mixed solvents of ethanol and deionized water. Single crystal X-ray diffraction study confirms that 2-Methylimidazolium D-tartrate belongs to monoclinic crystal system with non-centrosymmetric space group P21. The Fourier transform infrared spectrum of 2-Methylimidazolium D-tartrate reveals the presence of methyl and carboxyl functional groups in the compound. The mechanical properties of 2MImdT crystal were studied. The theoretical factor group analysis predicts 168 optical modes in the title compound. The dielectric behavior of 2MImdT crystals was studied at different frequencies and temperatures. Decomposition and melting point of 2MImdT were found using thermal measurements. SHG behavior of the title compound was demonstrated using Q-switched Nd:YAG laser.

Influence of molybdenum content on transformation behavior of high performance bridge steel during continuous cooling

International Nuclear Information System (INIS)

Chen, Jun; Tang, Shuai; Liu, Zhenyu; Wang, Guodong

2013-01-01

Highlights: ► The bainite transformation field was refined. ► The empirical equation to estimate the GF s was established. ► Transformation behavior was studied with serially increasing Mo addition. ► The molybdenum content can be lowered as the cooling rate is increased. ► GF transformation field is also shifted to right by increasing Mo content. - Abstract: The continuous-cooling-transformation (CCT) diagrams of high performance bridge steel with different molybdenum content were plotted by means of a combined method of dilatometry and metallography. The results show that the molybdenum addition of 0.17 wt% does not noticeably alter the transformation behavior, whereas 0.38 wt% significantly. In addition, the molybdenum addition of 0.38 wt% completely eliminates the formation of polygonal ferrite (PF) and significantly lower the granular ferrite (GF) transformation starting temperatures throughout the range of cooling rates studied. At lower cooling rates, with the increase of the molybdenum content, the martensite/austenite (M/A) constituents are noticeably refined, whereas the effects are not obvious at higher cooling rates. Moreover, the molybdenum addition of 0.38 wt% can significantly increase the Vickers hardness, but the Vickers hardness increments (by comparison of Mo-0.17wt% steel and Mo-0.38wt% steel) are sharply reduced at the cooling rate of 30 °C/s, indicating that at higher cooling rate, the molybdenum usage can be saved and the higher strengthen can be also gained. It could be found the GF transformation starting temperature is linear with the cooling rate. The empirical equation was established to calculate GF transformation starting temperatures, and the calculated values are in good agreement with measured ones

Influence of agronomic variables on the macronutrient and micronutrient contents and thermal behavior of mate tea leaves (Ilex paraguariensis).

Science.gov (United States)

Jacques, Rosângela A; Arruda, Eduardo J; de Oliveira, Lincoln C S; de Oliveira, Ana P; Dariva, Cláudio; de Oliveira, J Vladimir; Caramão, Elina B

2007-09-05

The influence of agronomic variables (light intensity, age of leaves, and fertilization type) on the content of macronutrients and micronutrients (potassium, calcium, sodium, magnesium, manganese, iron, zinc, and copper) of tea leaves was assessed by acid digestion, followed by flame atomic absorption spectrometry (FAAS). The thermal behavior of mate tea leaves (Ilex paraguariensis) was also studied in this work. Samples of mate (Ilex paraguariensis) were collected in an experiment conducted under agronomic control at Erva-Mate Barão Commerce and Industry LTD (Brazil). The results showed that the mineral content in mate is affected by the agronomic variables investigated. In general, the content of mineral compounds analyzed is higher for younger leaves and for plants cultivated in shadow. Thermal analysis of samples indicated a similar behavior, with three typical steps of decomposition: loss of water, degradation of low-molecular weight compounds, and degradation of residual materials.

Crystallization kinetics, glass transition kinetics, and thermal stability of Se70-xGa30Inx (x=5, 10, 15, and 20) semiconducting glasses

International Nuclear Information System (INIS)

Imran, Mousa M.A.

2011-01-01

Crystallization and glass transition kinetics of Se 70-x Ga 30 In x (x=5, 10, 15, and 20) semiconducting chalcogenide glasses were studied under non-isothermal condition using a Differential Scanning Calorimeter (DSC). DSC thermograms of the samples were recorded at four different heating rates 5, 10, 15, and 20 K/min. The variation of the glass transition temperature (T g ) with the heating rate (β) was used to calculate the glass transition activation energy (E t ) using two different models. Meanwhile, the variation of the peak temperature of crystallization (T p ) with β was utilized to deduce the crystallization activation energy (E c ) using Kissinger, Augis-Bennet, and Takhor models. Results reveal that E t decreases with increasing In content, while both T g and E c exhibit the opposite behavior, and the crystal growth occurs in one dimension. The variation of these thermal parameters with the average coordination number was also discussed, and the results were interpreted in terms of the type of bonding that In makes with Se. Assessment of thermal stability and glass forming ability (GFA) was carried out on the basis of some quantitative criteria and the results indicate that thermal stability is enhanced while the crystallization rate is reduced with the addition of In to Se-Ga glass. -- Research highlights: → Addition of In to Se-Ga glass decreases the glass transition activation energy. → The crystallization rate in Se-Ga-In glass is reduced as In content increases. → The crystal growth in Se-Ga-In glass occurs in one dimension. → Thermal properties of Se-Ga-In glass indicate a shift in Phillips-Thorpe threshold.

Dissolution enhancement of Deflazacort using hollow crystals prepared by antisolvent crystallization process.

Science.gov (United States)

Paulino, A S; Rauber, G; Campos, C E M; Maurício, M H P; de Avillez, R R; Capobianco, G; Cardoso, S G; Cuffini, S L

2013-05-13

Deflazacort (DFZ), a derivate of prednisolone, is a poorly soluble drug which has been proposed to have major advantages over other corticosteroids. Poorly soluble drugs present limited bioavailability due to their low solubility and dissolution rate and several strategies have been developed in order to find ways to improve them. In general, pharmaceutical laboratories use a micronized process to reduce the particle size in order to increase the dissolution of the drugs. However, this process causes changes such as polymorphic transitions, particle agglomeration and a reduction in fluidity and wettability. These solid-state properties affect the dissolution behavior and stability performance of drugs. Crystallization techniques are widely used in the pharmaceutical industry and antisolvent crystallization has been used to obtain ultrafine particles. In this study, DFZ was investigated in terms of its antisolvent crystallization in different solvents and under various preparation conditions (methanol/water ratio, stirring and evaporation rate, etc.), in order to compare the physicochemical properties between crystallized samples and raw materials available on the Brazilian market with and without micronization. Crystalline structure, morphology, and particle size, and their correlation with the Intrinsic Dissolution Rate (IDR) and dissolution profile as relevant biopharmaceutical properties were studied. Crystallization conditions were achieved which provided crystalline samples of hollow-shaped crystals with internal channels, which increased the dissolution rate of DFZ. The antisolvent crystallization process allowed the formation of hollow crystals, which demonstrated a better dissolution profile than the raw material (crystalline and micronized), making this a promising technique as a crystallization strategy for improving the dissolution and thus the bioavailability of poorly soluble drugs. Copyright © 2013 Elsevier B.V. All rights reserved.

Unique crystallization behavior of sodium manganese pyrophosphate Na2MnP2O7 glass and its electrochemical properties

Directory of Open Access Journals (Sweden)

Morito Tanabe

2017-06-01

Full Text Available Crystallization behavior of Na2MnP2O7 precursor glass was examined. Layered type Na2MnP2O7 was formed at 461 °C for 3 h in N2 filled electric furnace. Irreversible phase change was confirmed from layered Na2MnP2O7 to β-Na2MnP2O7 over 600 °C. At 650 °C crystallized phase was completely changed to β-phase. By means of charge and discharge testing it is found that layered Na2MnP2O7 is also active as cathode in sodium ion batteries. We found glass-ceramics technology is one of the suitable process for the synthesis of layered Na2MnP2O7 cathode without any complicate process.

Effect of borax on the wetting properties and crystallization behavior of sodium sulfate

NARCIS (Netherlands)

Granneman, S.J.C.; Shahidzadeh, N.; Lubelli, B.A.; Hees, R.P.J. van

2017-01-01

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the

Nonlinear dynamical phenomena in liquid crystals

International Nuclear Information System (INIS)

Wang, X.Y.; Sun, Z.M.

1988-09-01

Because of the existence of the orientational order and anisotropy in liquid crystals, strong nonlinear phenomena and singular behaviors, such as solitary wave, transient periodic structure, chaos, fractal and viscous fingering, can be excited by a very small disturbance. These phenomena and behaviors are in connection with physics, biology and mathematics. 12 refs, 6 figs

Influences of Cr content and PWHT on microstructure and oxidation behavior of stainless steel weld overlay cladding materials in high temperature water

Energy Technology Data Exchange (ETDEWEB)

Cao, X.Y.; Ding, X.F. [National Center for Materials Service Safety, University of Science and Technology Beijing, 30 Xueyuan Road, 100083 Beijing (China); Lu, Y.H., E-mail: lu_yonghao@mater.ustb.edu.cn [National Center for Materials Service Safety, University of Science and Technology Beijing, 30 Xueyuan Road, 100083 Beijing (China); Zhu, P. [Suzhou Nuclear Power Research Institute Co. Ltd., 1788 Xihuan Road, 215004 Suzhou (China); Shoji, T. [National Center for Materials Service Safety, University of Science and Technology Beijing, 30 Xueyuan Road, 100083 Beijing (China); Fracture and Reliability Research Institute, Tohoku University, 6-6-01 Aramaki Aoba, Aoba-ku, Sendai City 980-8579 (Japan)

2015-12-15

Influences of Cr content and post weld heat treatment (PWHT) on microstructure and oxidation behavior of stainless steel cladding materials in high temperature water were investigated. The amounts of metal oxidized and dissolved were estimated to compare the oxidation behaviors of cladding materials with different Cr contents and PWHT. The results indicated that higher Cr content led to formation of more ferrite content, and carbides were found along δ/γ phase interface after PWHT. Higher Cr content enhanced the pitting resistance and compactness of the oxide film to reduce metal amount oxidized and dissolved, which mitigated the weight changes and the formation of Fe-rich oxides. PWHT promoted more and deeper pitting holes along the δ/γ phase interface due to formation of carbides, which resulted in an increase in metal amount oxidized and dissolved, and were also responsible for more Fe-rich oxides and higher weight changes. - Highlights: • The amounts of metal oxidized and metal dissolved were estimated. • Higher Cr content increased ferrite content and PWHT led to formation of carbides. • PWHT promoted more and deeper pitting holes along the δ/γ phase interface. • Lower Cr content and PWHT promoted the metal amounts oxidized and dissolved. • Lower Cr content and PWHT increased weight changes and Fe-rich film formation.

ThMn12-type phases for magnets with low rare-earth content: Crystal-field analysis of the full magnetization process.

Science.gov (United States)

Tereshina, I S; Kostyuchenko, N V; Tereshina-Chitrova, E A; Skourski, Y; Doerr, M; Pelevin, I A; Zvezdin, A K; Paukov, M; Havela, L; Drulis, H

2018-02-26

Rare-earth (R)-iron alloys are a backbone of permanent magnets. Recent increase in price of rare earths has pushed the industry to seek ways to reduce the R-content in the hard magnetic materials. For this reason strong magnets with the ThMn 12  type of structure came into focus. Functional properties of R(Fe,T) 12 (T-element stabilizes the structure) compounds or their interstitially modified derivatives, R(Fe,T) 12 -X (X is an atom of hydrogen or nitrogen) are determined by the crystal-electric-field (CEF) and exchange interaction (EI) parameters. We have calculated the parameters using high-field magnetization data. We choose the ferrimagnetic Tm-containing compounds, which are most sensitive to magnetic field and demonstrate that TmFe 11 Ti-H reaches the ferromagnetic state in the magnetic field of 52 T. Knowledge of exact CEF and EI parameters and their variation in the compounds modified by the interstitial atoms is a cornerstone of the quest for hard magnetic materials with low rare-earth content.

The melting and crystallization behavior of irradiated poly(1-butene)

International Nuclear Information System (INIS)

Markovic, V.; Silverman, J.

1982-01-01

Isotactic poly(1-butene) samples were melted and crystallized. This treatment leaves the polymer in the unstable crystalline form, known as Modification II. The transformation to stable Modification I normally has a half life of 1 day. Samples were irradiated within 30 min after crystallization with high doses of electrons delivered in intervals up to a few minutes. This permitted measurements of radiation effects on Modification II under circumstances where the II-I crystal transformation was negligibly small. Similar measurements were performed on stable Modification I, which was obtained by waiting for the completion of the II-I transformation; for this stable crystalline form, relatively low dose rate γ-exposures serve as well as high dose rate electron beams in measuring radiation effects. DSC and IR absorption measurements were performed. The effect of radiation on the fusion endotherms, melting points, IR spectra, and some aspects of the kinetics of crystalline transformation are presented. (author)

Hydrophilicity, pore structure and mechanical performance of CNT/PVDF materials affected by carboxyl contents in multi-walled carbon nanotubes

Science.gov (United States)

Zhang, Yanxia; Jiang, Ce; Tian, Run; Li, Guangfen

2018-01-01

Poly (vinylidene fluoride) (PVDF) membranes have been prepared by loading different type of MWCNTs-COOH as the dispersed phase via phase inversion method. The chemically functionalized MWCNTs with increasing carboxyl content were chosen for achieving a better dispersion in PVDF and altering the membrane hydrophilicity. The effect of the carboxyl content in MWCNTs on crystal structure, thermal behavior, membrane morphology, hydrophilicity, and water flux of blended membranes were investigated. Due to the addition of carbon nanotubes, various performances of the hybrid membrane had obvious changes. The most prominent was that thermal stability could be enhanced and the pore morphology was more preferable, also that the hydrophilicity were improved, further that water flux could be increased to some extent.

Dramatic improvement of crystal quality for low-­temperature-grown rabbit muscle aldolase

Science.gov (United States)

Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice. PMID:20445268

Crystal structure, Raman scattering and magnetic properties of CuCr2-xZrxSe4 and CuCr2-xSnxSe4 selenospinels

Science.gov (United States)

Pinto, C.; Galdámez, A.; Barahona, P.; Moris, S.; Peña, O.

2018-06-01

Selenospinels, CuCr2-xMxSe4 (M = Zr and Sn), were synthesized via conventional solid-state reactions. The crystal structure of CuCr1.5Sn0.5Se4, CuCr1.7Sn0.3Se4, CuCr1.5Zr0.5Se4, and CuCr1.8Zr0.2Se4 were determined using single-crystal X-ray diffraction. All the phases crystallized in a cubic spinel-type structure. The chemical compositions of the single-crystals were examined using energy-dispersive X-ray analysis (EDS). Powder X-ray diffraction patterns of CuCr1.3Sn0.7Se4 and CuCr1.7Sn0.3Se4 were consistent with phases belonging to the Fd 3 bar m Space group. An analysis of the vibrational properties on the single-crystals was performed using Raman scattering measurements. The magnetic properties showed a spin glass behavior with increasing Sn content and ferromagnetic order for CuCr1.7Sn0.3Se4.

Probing the crossover in CO desorption from single crystal to nanoparticulate Ru model catalysts

DEFF Research Database (Denmark)

Murphy, Shane; Strebel, Christian Ejersbo; Vendelbo, Søren Bastholm

2011-01-01

Crossover in CO desorption behavior and nanoscale structure probed with STM from ruthenium single crystals to PVD and mass-selected nanoparticles.......Crossover in CO desorption behavior and nanoscale structure probed with STM from ruthenium single crystals to PVD and mass-selected nanoparticles....

Distributions of crystals and gas bubbles in reservoir ice during growth period

Directory of Open Access Journals (Sweden)

Zhi-jun Li

2011-06-01

Full Text Available In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted in the fast and steady ice growth stages. Ice pieces were used to observe ice crystals and gas bubbles in ice, and to measure the ice density. Vertical profiles of the type and size of ice crystals, shape and size of gas bubbles, and gas bubble content, as well as the ice density, were obtained. The results show that the upper layer of the ice pieces is granular ice and the lower layer is columnar ice; the average crystal size increases with the ice depth and remains steady in the fast and steady ice growth stages; the shape of gas bubbles in the upper layer of ice pieces is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content vary with the ice growth stage; and the ice density decreases with the increase of the gas bubble content.

Martensitic transformations of Cu-Al-Ni single crystals in tension/compression

Energy Technology Data Exchange (ETDEWEB)

Novak, V.; Sittner, P. [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Physics; Humbeeck, J. van [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Physics; Catholic Univ. of Leuven, Heverlee (Belgium). MTM Dept.

2001-11-01

Cu-Al-Ni alloys, similarly as other Cu-base shape memory alloys, transform into more martensitic structures {alpha}{sub 1}' (6R), {beta}{sub 1}' (18R) and {gamma}{sub 1}' (2H), depending on the temperature, stress, load axis orientation, sense of loading and composition. The transformation stress-temperature conditions at which individual transitions take place are beneficially represented in so called non-equilibrium stress-temperature phase diagrams. On the basis of the {sigma}-T diagrams, complex history dependent thermomechanical behaviors of SMA single crystals undergoing sequentially multiple solid state transitions can be easily understood and predicted. Since chemical composition of the alloy crystals affects mainly the equilibrium transformation temperatures, T{sub 0}, and only slightly the slopes of the transformation lines in the {sigma}-T diagrams, the diagrams mainly shift in the temperature range (over {proportional_to}200K) with the compositional variations. The shape of the diagrams, however, may change significantly when the T{sub 0} shifts for individual transitions are different. Knowledge of the compositional dependence of {sigma}-T diagrams would be beneficial for the development of shape memory alloys with specific required thermomechanical properties. The aim of the present work is experimental investigation of the martensitic transformations and construction of the {sigma}-T diagram for Cu-Al-Ni alloy with lower Al content (T{sub 0}>363K) and comparison with our previous results obtained on alloys with higher Al content (T{sub 0}<263K). (orig.)

Dramatic improvement of crystal quality for low-temperature-grown rabbit muscle aldolase

International Nuclear Information System (INIS)

Park, HaJeung; Rangarajan, Erumbi S.; Sygusch, Jurgen; Izard, Tina

2010-01-01

Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. Rabbit muscle aldolase (RMA) was crystallized in complex with the low-complexity domain (LC4) of sorting nexin 9. Monoclinic crystals were obtained at room temperature that displayed large mosaicity and poor X-ray diffraction. However, orthorhombic RMA–LC4 crystals grown at 277 K under similar conditions exhibited low mosaicity, allowing data collection to 2.2 Å Bragg spacing and structure determination. It was concluded that the improvement of crystal quality as indicated by the higher resolution of the new RMA–LC4 complex crystals was a consequence of the introduction of new lattice contacts at lower temperature. The lattice contacts corresponded to an increased number of interactions between high-entropy side chains that mitigate the lattice strain incurred upon cryocooling and accompanying mosaic spread increases. The thermodynamically unfavorable immobilization of high-entropy side chains used in lattice formation was compensated by an entropic increase in the bulk-solvent content owing to the greater solvent content of the crystal lattice

Study of crystallization kinetics and structural relaxation behavior in phase separated Ag{sub 33}Ge{sub 17}Se{sub 50} glassy alloys

Energy Technology Data Exchange (ETDEWEB)

Kumar, Praveen, E-mail: prafiziks@gmail.com [Semiconductors Laboratory, Department of Physics, GND University, Amritsar 143005 (India); Nanotechnology Research Centre, DAV Institute of Engineering and Technology, Kabir Nagar, Jalandhar 144008 (India); Yannopoulos, S.N. [Foundation for Research and Technology Hellas, Institute of Chemical Engineering and High Temperature Chemical Processes (FORTH/ICE-HT), P.O. Box 1414, GR-26 504, Rio-Patras (Greece); Sathiaraj, T.S. [Department of Physics, University of Botswana, Gaborone (Botswana); Thangaraj, R., E-mail: rthangaraj@rediffmail.com [Semiconductors Laboratory, Department of Physics, GND University, Amritsar 143005 (India)

2012-07-16

We report on the crystallization processes and structure (crystal phases) of Ag{sub 33}Ge{sub 17}Se{sub 50} glassy alloy using differential scanning calorimetry and x-ray diffraction techniques, respectively. The devitrification that gives rise to the first exothermic peak results in the crystallization of Ag{sub 2}Se and Ag{sub 8}GeSe{sub 6} phases, while the growth of GeSe{sub 2} accompanied by the transformation of Ag{sub 8}GeSe{sub 6} to Ag{sub 2}Se phase occurs during the second crystallization process. Different theoretical models are used to elucidate various kinetic parameters for the crystallization transformation process in this phase separated system. With annealing below the glass transition temperature, an inverse behavior between the variation of the optical gap and the band tailing parameter is observed for the thermally evaporated films. These results are explained as the mixing of different clusters/species in the amorphous state and/or changes caused by structural relaxation of the glassy network for the thermally evaporated films. - Highlights: Black-Right-Pointing-Pointer Phase separation in Ag{sub 33}Ge{sub 17}Se{sub 50} glassy alloy bordering two glass forming regions. Black-Right-Pointing-Pointer Transformation of Ag{sub 8}GeSe{sub 6} {yields} Ag{sub 2}Se along with crystallization GeSe{sub 2} phase. Black-Right-Pointing-Pointer Elucidation of various kinetic parameters for the crystalline transformation. Black-Right-Pointing-Pointer Structural relaxation in thermally evaporated films by optical spectroscopy.

A content analysis of preconception health education materials: characteristics, strategies, and clinical-behavioral components.

Science.gov (United States)

Levis, Denise M; Westbrook, Kyresa

2013-01-01

Many health organizations and practitioners in the United States promote preconception health (PCH) to consumers. However, summaries and evaluations of PCH promotional activities are limited. We conducted a content analysis of PCH health education materials collected from local-, state-, national-, and federal-level partners by using an existing database of partners, outreach to maternal and child health organizations, and a snowball sampling technique. Not applicable. Not applicable. Thirty-two materials were included for analysis, based on inclusion/exclusion criteria. A codebook guided coding of materials' characteristics (type, authorship, language, cost), use of marketing and behavioral strategies to reach the target population (target audience, message framing, call to action), and inclusion of PCH subject matter (clinical-behavioral components). The self-assessment of PCH behaviors was the most common material (28%) to appear in the sample. Most materials broadly targeted women, and there was a near-equal distribution in targeting by pregnancy planning status segments (planners and nonplanners). "Practicing PCH benefits the baby's health" was the most common message frame used. Materials contained a wide range of clinical-behavioral components. Strategic targeting of subgroups of consumers is an important but overlooked strategy. More research is needed around PCH components, in terms of packaging and increasing motivation, which could guide use and placement of clinical-behavioral components within promotional materials.

Preparation, melting behavior and thermal stability of poly(lactic acid)/poly(propylene carbonate) blends processed by vane extruder

Energy Technology Data Exchange (ETDEWEB)

Zou, Wei, E-mail: zw55624@163.com; Chen, Rongyuan; Zhang, Haichen; Qu, Jinping, E-mail: jpqu@scut.edu.cn [National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640 (China)

2016-03-09

Poly (lactic acid) (PLA)/Poly (propylene carbonate) (PPC) blends were prepared by vane extruder which is a type of novel polymer processing extruder based on elongation force field. Scanning electron microscope (SEM), differential scanning calorimetry (DSC) and thermogravimetric (TG) were used respectively to analyze the compatibility, the melting behavior and thermal stability properties of PLA/PPC blends affected by the different content of PPC. The results showed that with the increase of the PPC content, the glass transition temperature of PLA was reduced, and the glass transition temperature of PPC was increased, which indicated that PLA and PPC had partial compatibility. The cold crystallization temperature of PLA increased with the increase of the PPC content, which showed that PPC hindered the cold crystallization process of PLA. The addition of PPC had little impact on the melting process of PLA, and the melting temperature of PLA was almost kept the same value. Thermogravimetric analysis showed that the thermal stability of PPC was worse than that of PLA, the addition of PPC reduced the thermal stability of PLA.

UHMW Ziegler–Natta polyethylene: Synthesis, crystallization, and melt behavior

KAUST Repository

Atiqullah, Muhammad; Adamu, Sagir; Emwas, Abdul-Hamid M.

2017-01-01

nonisothermal crystallization model, Flory's equilibrium theory and ethylene sequence length distribution concept (SLD), Gibbs–Thompson equation, and DSC experiments. By using this approach, the effects of MW, 1-hexene incorporation, ethylene SLD, the level

Discovery of room-temperature spin-glass behaviors in two-dimensional oriented attached single crystals

Energy Technology Data Exchange (ETDEWEB)

Ma, Ji; Chen, Kezheng, E-mail: kchen@qust.edu.cn

2016-05-15

In this study, room-temperature spin-glass behaviors were observed in flake-like oriented attached hematite (α-Fe{sub 2}O{sub 3}) and iron phosphate hydroxide hydrate (Fe{sub 5}(PO{sub 4}){sub 4}(OH){sub 3}·2H{sub 2}O) single crystals. Remarkably, their coercivity (H{sub C}) 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. - Highlights: • Room-temperature spin-glass state was found in 2D oriented attached single crystals. • Coercivity values were found to be almost invariable at different temperatures. • The spin topographic map was assumed as SPM “islands” isolated by SG-like “bridges”.

A thermodynamic framework for the study of crystallization in polymers

Science.gov (United States)

Rao, I. J.; Rajagopal, K. R.

In this paper, we present a new thermodynamic framework within the context of continuum mechanics, to predict the behavior of crystallizing polymers. The constitutive models that are developed within this thermodynamic setting are able to describe the main features of the crystallization process. The model is capable of capturing the transition from a fluid like behavior to a solid like behavior in a rational manner without appealing to any adhoc transition criterion. The anisotropy of the crystalline phase is built into the model and the specific anisotropy of the crystalline phase depends on the deformation in the melt. These features are incorporated into a recent framework that associates different natural configurations and material symmetries with distinct microstructural features within the body that arise during the process under consideration. Specific models are generated by choosing particular forms for the internal energy, entropy and the rate of dissipation. Equations governing the evolution of the natural configurations and the rate of crystallization are obtained by maximizing the rate of dissipation, subject to appropriate constraints. The initiation criterion, marking the onset of crystallization, arises naturally in this setting in terms of the thermodynamic functions. The model generated within such a framework is used to simulate bi-axial extension of a polymer film that is undergoing crystallization. The predictions of the theory that has been proposed are consistent with the experimental results (see [28] and [7]).

A probabilistic analysis of the crystal oscillator behavior at low drive levels

Science.gov (United States)

Shmaliy, Yuriy S.; Brendel, Rémi

2008-03-01

The paper discusses a probabilistic model of a crystal oscillator at low drive levels where the noise intensity is comparable with the oscillation amplitude. The stationary probability density of the oscillations envelope is derived and investigated for the nonlinear resonator loses. A stochastic explanation is given for the well-known phenomenon termed sleeping sickness associated with losing a facility of self-excitation by a crystal oscillator after a long storage without a power supply. It is shown that, with low drive levels leading to an insufficient feedback, a crystal oscillator generates the noise-induced oscillations rather than it absolutely "falls in sleep".

Ultrasonic characterization of pork fat crystallization during cold storage.

Science.gov (United States)

Corona, Edith; García-Pérez, José V; Santacatalina, Juan V; Ventanas, Sonia; Benedito, José

2014-05-01

In this work, the feasibility of using ultrasonic velocity measurements for characterizing and differentiating the crystallization pattern in 2 pork backfats (Montanera and Cebo Iberian fats) during cold storage (0 °C, 2 °C, 5 °C, 7 °C, and 10 °C) was evaluated. The fatty acid profile, thermal behavior, and textural properties (hardness) of fat were also determined. Both fats became harder during cold storage (average hardness increase for both fats, 11.5 N, 8 N, and 1.8 N at 0, °C 2 °C, and 5 °C , respectively), showing a 2-step pattern related with the separate crystallization of the different existing triacylglycerols, which was well described using a modified Avrami equation (explained variance > 99%). Due to a greater content of saturated triacylglycerols, Cebo fat (45.1%) was harder than Montanera (41.8%). The ultrasonic velocity followed a similar 2-step pattern to hardness during cold storage, being found an average increase for both fats of 184, 161, and 150 m/s at 0 °C 2 °C, and 5 °C, respectively. Thus, ultrasonic measurements were useful both to characterize the textural changes taking place during cold storage and to differentiate between fats with different composition. The cold storage of dry-cured meat products during their distribution and retail sale exert an important effect on their textural properties and consumers' acceptance due to the crystallization of the fat fraction, which is greatly influenced by the type of fat. In this work, a nondestructive ultrasonic technique was used to identify the textural changes provoked by the crystallization during cold storage, and to differentiate between fats, which could be used for quality control purposes. © 2014 Institute of Food Technologists®

Dependence of magnetization on crystal fields and exchange interactions in magnetite

Energy Technology Data Exchange (ETDEWEB)

Ouaissa, Mohamed, E-mail: m.ouaissa@yahoo.fr [Laboratoire de Génie Physique et Environnement, Faculté des Sciences, Université Ibn Tofail, Campus Universitaire BP 133, Kénitra 14000 (Morocco); Benyoussef, Abdelilah [Laboratory of Magnetism and Physics of High Energy, Faculty of Science, Mohammed V-Agdal University, Rabat (Morocco); Abo, Gavin S. [Department of Electrical and Computer Engineering and MINT Center, The University of Alabama, Tuscaloosa, AL 35487 (United States); Ouaissa, Samia; Hafid, Mustapha [Laboratoire de Génie Physique et Environnement, Faculté des Sciences, Université Ibn Tofail, Campus Universitaire BP 133, Kénitra 14000 (Morocco); Belaiche, Mohammed [Laboratoire de Magnétisme, Matériaux Magnétiques, Microonde et Céramique, Ecole Normale Supérieure, Université Mohammed V-Agdal, B.P. 9235, Océan, Rabat (Morocco)

2015-11-15

In this work, we study the magnetization of magnetite (Fe{sub 3}O{sub 4}) with different exchange interactions and crystal fields using variational method based on the Bogoliubov inequality for the Gibbs free energy within the mean field theory. The magnetic behavior was investigated in the absence and presence of crystal fields. The investigations also revealed that the transition temperature depends on the crystal fields of the octahedral and tetrahedral sites. Magnetite exhibits ferrimagnetic phase with second order transition to paramagnetic phase at 850 K. This result is confirmed using the mean field theory within the Heisenberg model. Important factors that can affect the magnetic behavior of the system are exchange interactions and crystal field. Indeed, a new magnetic behavior was observed depending on these parameters. A first order phase transition from ferrimagnetic to ferromagnetic was found at low temperature, and a second order transition from ferromagnetic to paramagnetic was observed at high temperature. - Highlights: • Magnetization of magnetite versus temperature was studied by mean field theory. • The critical temperature of magnetite (Fe{sub 3}O{sub 4}) was approximately obtained. • Effect of sublattice crystal fields on the magnetization of Fe{sub 3}O{sub 4} was investigated.

One-dimensional magnetophotonic crystals with magnetooptical double layers

International Nuclear Information System (INIS)

Berzhansky, V. N.; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V.; Lukienko, I. N.; Kharchenko, Yu. N.; Golub, V. O.; Salyuk, O. Yu.; Belotelov, V. I.

2016-01-01

One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ F and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ F =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ F =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

One-dimensional magnetophotonic crystals with magnetooptical double layers

Energy Technology Data Exchange (ETDEWEB)

Berzhansky, V. N., E-mail: v.n.berzhansky@gmail.com; Shaposhnikov, A. N.; Prokopov, A. R.; Karavainikov, A. V.; Mikhailova, T. V. [V.I. Vernadsky Crimean Federal University (Russian Federation); Lukienko, I. N.; Kharchenko, Yu. N., E-mail: kharcenko@ilt.kharkov.ua [National Academy of Sciences of Ukraine, Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Golub, V. O., E-mail: v-o-golub@yahoo.com; Salyuk, O. Yu. [National Academy of Sciences of Ukraine, Institute of Magnetism (Ukraine); Belotelov, V. I., E-mail: belotelov@physics.msu.ru [Russian Quantum Center (Russian Federation)

2016-11-15

One-dimensional magnetophotonic microcavity crystals with nongarnet dielectric mirrors are created and investigated. The defect layers in the magnetophotonic crystals are represented by two bismuth-substituted yttrium iron garnet Bi:YIG layers with various bismuth contents in order to achieve a high magnetooptical response of the crystals. The parameters of the magnetophotonic crystal layers are optimized by numerical solution of the Maxwell equations by the transfer matrix method to achieve high values of Faraday rotation angle Θ{sub F} and magnetooptical Q factor. The calculated and experimental data agree well with each other. The maximum values of Θ{sub F} =–20.6°, Q = 8.1° at a gain t = 16 are obtained for magnetophotonic crystals with m = 7 pairs of layers in Bragg mirrors, and the parameters obtained for crystals with m = 4 and t = 8.5 are Θ{sub F} =–12.5° and Q = 14.3°. It is shown that, together with all-garnet and multimicrocavities magnetophotonic crystals, such structures have high magnetooptical characteristics.

Crystallization and preliminary X-ray analysis of vicenisaminyltransferase VinC

International Nuclear Information System (INIS)

Nango, Eriko; Minami, Atsushi; Kumasaka, Takashi; Eguchi, Tadashi

2008-01-01

The crystallization of VinC, a glycosyltransferase involved in the biosynthesis of the antitumour antibiotic vicenistatin, is reported. A recombinant glycosyltransferase, VinC, from Streptomyces halstedii HC34 has been crystallized at 293 K using PEG 3350 as precipitant. The diffraction pattern of the crystal extends to 2.0 Å resolution at 100 K using synchrotron radiation at SPring-8. The crystals are orthorhombic and belong to space group I222, with unit-cell parameters a = 98.21, b = 130.39, c = 140.11 Å. The presence of two molecules per asymmetric unit gives a crystal volume per protein weight (V M ) of 2.43 Å 3 Da −1 and a solvent content of 49.5% by volume

XRD and SEM study on the phase separation and crystallization behavior for an amorphous Cu+ conductor

International Nuclear Information System (INIS)

Yang Yuan; Hou Jianguo; Yu Wenhai

1990-01-01

The X-ray diffraction (XRD) and scanning electron microscopy (SEM) study was carried out for an amorphous Cu + conductor 0.4 CuI-0.3 Cu 2 O-0.3 P 2 O 5 with the simultaneous conductivity measurement in the isothermal heat treament process. The results indicated that the initial amorphous material was phase-separated. In the course of time the separated amorphous phase disappeared, the crystalline γ-CuI and Cu 2 P 2 O 7 formed in sequence and grew up gradually. The correlation of the phase separation and crystallization behavior with the conductivity anomaly confirmed again the interface effect between different phases in amorphous fast ionic conductors and its universality

Explaining nutritional habits and behaviors of low socioeconomic status women in Sanandaj: a qualitative content analysis.

Science.gov (United States)

Abdi, Nasrin; Sadeghi, Roya; Zamani-Alavijeh, Fereshteh; Taghdisi, Mohammad Hossein; Shojaeezadeh, Davoud

2016-01-01

Health and behavior are closely related subjects because disease is typically rooted in individuals' unhealthy behaviors and habits. This study aims to identify women's nutritional habits and behaviors in order to design interventions to promote nutritional literacy. This qualitative research is part of a mixed method (quantitative-qualitative) study, conducted based on content analysis. Data were collected using semistructured interviews, group discussions, and in-depth interviews with married women, aged 18-50 years, who were referred to four health care centers in Sanandaj in 2013-2014. Nutritional habits and behaviors of participants were classified into two categories: representation of nutritional behavior based on consumption pattern and representation of nutritional behavior based on consumption method. For the former, eight consumption pattern subcategories were formed: meat, dairy, fast food, local foods, fruits and vegetables, soft drinks, and oils. The latter (representation of nutritional behavior based on consumption method), included two subcategories: consumption method in line with health and consumption method inconsistent with health. Results of this qualitative study provide a solid foundation for development and designing interventions to nutritional literacy promotion based on needs. The designed intervention to healthy nutritional behavior should be based on empowering women and providing facilitator factors of a healthy diet. While designing this study, with a holistic perspective, individual and social aspects of a healthy diet should be taken into account.

Passive integrated circuits utilizing slow light in photonic crystal waveguides

DEFF Research Database (Denmark)

Lavrinenko, Andrei; Têtu, Amélie; Yang, Lirong

2006-01-01

We report thorough investigations of photonic crystal waveguide properties in the slow light regime. The transmission and the group index near the cutoff wavelengths oscillate in phase in close analogy with the ID photonic crystal behavior. The influence of having a finite number of periods...

Face-selective crystal growth behavior of L-aspartic acid in the presence of L-asparagine

Science.gov (United States)

Sato, Hiroyasu; Doki, Norihito; Yoshida, Saki; Yokota, Masaaki; Shimizu, Kenji

2016-02-01

The kinetic mechanism of L-asparagine (L-Asn) action on L-aspartic acid (L-Asp) crystal growth, namely the face-selective effect of L-Asn on the L-Asp crystal growth rate in each direction, was examined. In the a-axis direction, the effect of L-Asn on the L-Asp crystal growth rate was small. Enhancement and inhibition of L-Asp crystal growth, and interestingly the dissolution of the L-Asp crystal face, were observed in the b-axis direction, depending on the amount of L-Asn added. In the c-axis direction, the L-Asp crystal growth rate decreased with the increase in the amount of L-Asn added, and the experimental results were well fitted with a Langmuir adsorption isotherm. The study showed that there were crystal growth conditions where enhancement and inhibition, as well as inhibition and dissolution, coexisted in the presence of an additive with a structure similar to the growing crystal.

Elastic properties of Ti-24Nb-4Zr-8Sn single crystals with bcc crystal structure

International Nuclear Information System (INIS)

Zhang, Y.W.; Li, S.J.; Obbard, E.G.; Wang, H.; Wang, S.C.; Hao, Y.L.; Yang, R.

2011-01-01

Research highlights: → The single crystals of Ti2448 alloy with the bcc crystal structure were prepared. → The elastic moduli and constants were measured by several resonant methods. → The crystal shows significant elastic asymmetry in tension and compression. → The crystal exhibits weak nonlinear elasticity with large elastic strain ∼2.5%. → The crystal has weak atomic interactions against crystal distortion to low symmetry. - Abstract: Single crystals of Ti2448 alloy (Ti-24Nb-4Zr-8Sn in wt.%) were grown successfully using an optical floating-zone furnace. Several kinds of resonant methods gave consistent Young's moduli of 27.1, 56.3 and 88.1 GPa and shear moduli of 34.8, 11.0 and 14.6 GPa for the , and oriented single crystals, and C 11 , C 12 and C 44 of 57.2, 36.1 and 35.9 GPa respectively. Uniaxial testing revealed asymmetrical elastic behaviors of the crystals: tension caused elastic softening with a large reversible strain of ∼4% and a stress plateau of ∼250 MPa, whereas compression resulted in gradual elastic stiffening with much smaller reversible strain. The crystals exhibited weak nonlinear elasticity with a large elastic strain of ∼2.5% and a high strength, approaching ∼20% and ∼30% of its ideal shear and ideal tensile strength respectively. The crystals showed linear elasticity with a small elastic strain of ∼1%. These elastic deformation characteristics have been interpreted in terms of weakened atomic interactions against crystal distortion to low crystal symmetry under external applied stresses. These results are consistent with the properties of polycrystalline Ti2448, including high strength, low elastic modulus, large recoverable strain and weak strengthening effect due to grain refinement.

Key Developments in Ionic Liquid Crystals.

Science.gov (United States)

Alvarez Fernandez, Alexandra; Kouwer, Paul H J

2016-05-16

Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

Key Developments in Ionic Liquid Crystals

Directory of Open Access Journals (Sweden)

Alexandra Alvarez Fernandez

2016-05-01

Full Text Available Ionic liquid crystals are materials that combine the classes of liquid crystals and ionic liquids. The first one is based on the multi-billion-dollar flat panel display industry, whilst the latter quickly developed in the past decades into a family of highly-tunable non-volatile solvents. The combination yields materials with a unique set of properties, but also with many challenges ahead. In this review, we provide an overview of the key concepts in ionic liquid crystals, particularly from a molecular perspective. What are the important molecular parameters that determine the phase behavior? How should they be introduced into the molecules? Finally, which other tools does one have to realize specific properties in the material?

Final Report - Effects of High Spinel and Chromium Oxide Crystal Contents on Simulated HLW Vitrification in DM100 Melter Tests, VSL-09R1520-1, Rev. 0, dated 6/22/09

Energy Technology Data Exchange (ETDEWEB)

Kruger, Albert A.; Matlack, K. S.; Kot, W.; Pegg, I. L.; Chaudhuri, M.; Lutze, W.

2013-11-13

The principal objective of the work was to evaluate the effects of spinel and chromium oxide particles on WTP HLW melter operations and potential impacts on melter life. This was accomplished through a combination of crucible-scale tests, settling and rheological tests, and tests on the DM100 melter system. Crucible testing was designed to develop and identify HLW glass compositions with high waste loadings that exhibit formation of crystalline spinel and/or chromium oxide phases up to relatively high crystal contents (i.e., > 1 vol%). Characterization of crystal settling and the effects on melt rheology was performed on the HLW glass formulations. Appropriate candidate HLW glass formulations were selected, based on characterization results, to support subsequent melter tests. In the present work, crucible melts were formulated that exhibit up to about 4.4 vol% crystallization.

Effect of titanium dioxide (TiO2) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

International Nuclear Information System (INIS)

Wang, Shichao; Zhang, Jun

2014-01-01

Highlights: • HDPE/TiO 2 composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO 2 composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO 2 ) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO 2 particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO 2 particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO 2 particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO 2 particles in HDPE matrix. It was found the rutile TiO 2 could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result

Picosecond laser pulse-driven crystallization behavior of SiSb phase change memory thin films

International Nuclear Information System (INIS)

Huang Huan; Li Simian; Zhai Fengxiao; Wang Yang; Lai Tianshu; Wu Yiqun; Gan Fuxi

2011-01-01

Highlights: → We reported crystallization dynamics of a novel SiSb phase change material. → We measured optical constants of as-deposited and irradiated SiSb areas. → Optical properties of as-deposited and irradiated SiSb thin film were compared. → Crystallization of irradiated SiSb was confirmed by using AFM and micro-Raman spectra. → The heat conduction effect of lower metal layer of multi-layer films was studied. - Abstract: Transient phase change crystallization process of SiSb phase change thin films under the irradiation of picosecond (ps) laser pulse was studied using time-resolved reflectivity measurements. The ps laser pulse-crystallized domains were characterized by atomic force microscope, Raman spectra and ellipsometrical spectra measurements. A reflectivity contrast of about 15% can be achieved by ps laser pulse-induced crystallization. A minimum crystallization time of 11 ns was achieved by a low-fluence single ps laser pulse after pre-irradiation. SiSb was shown to be very promising for fast phase change memory applications.

Modeling Nonlinear Elastic-plastic Behavior of RDX Single Crystals During Indentation

Science.gov (United States)

2012-01-01

single crystals has also been probed using shock experiments (6, 12) and molecular dynamics simulations (12–14). RDX undergoes a polymorphic phase...Patterson, J.; Dreger, Z.; Gupta, Y. Shock-wave Induced Phase Transition in RDX Single Crystals. J. Phys. Chem. B 2007, 111, 10897–10904. 17. Bedrov, D...and Volume Compression of β - HMX and RDX . In Proc. Int. Symp. High Dynamic Pressures; Commissariat a l’Energie Atomique: Paris, 1978; pp 3–8. 24

Quality evaluation of resistivity-controlled silicon crystals

Science.gov (United States)

Wang, Jong Hoe

2006-01-01

The segregation phenomenon of dopants causes a low production yield of silicon crystal that meets the resistivity tolerance required by device manufacturers. In order to control the macroscopic axial resistivity distribution in bulk crystal growth, numerous studies including continuous Czochralski method and double crucible technique have been studied. The simple B-P codoping method for improving the productivity of p-type silicon single-crystal growth by controlling axial specific resistivity distribution was proposed by Wang [Jpn. J. Appl. Phys. 43 (2004) 4079]. In this work, the quality of Czochralski-grown silicon single crystals with a diameter 200 mm using B-P codoping method was studied from the chemical and structural points of view. It was found that the characteristics of B-P codoped wafers including the oxygen precipitation behavior and the grown-in defects are same as that of conventional B-doped Czochralski crystals.

Combining Pre- and Post-Nucleation Trajectories for the Synthesis of High FAU-Content Faujasite Nanocrystals from Organic-Free Sols

Energy Technology Data Exchange (ETDEWEB)

Khaleel, Maryam; Xu, Wenqian; Lesch, David A.; Tsapatsis, Michael

2016-06-28

The effects of synthesis conditions on the FAU/EMT content and the size of nanocrystals, formed from inorganic aluminosilicate sols, were investigated. High resolution transmission electron microscopy imaging and comparison of experimental X-ray diffraction patterns with simulations demonstrated that all materials made starting from synthesis mixtures in the composition range (1.8-33) SiO2: 1 Al2O3: (2.7-33) Na2O: (41-1000) H2O contain FAU/EMT intergrowths. Compositions with low water content increase the FAU fraction up to 0.8 but the crystal size exceeds 100 nm. Extension of the higher FAU purity to nanocrystals was achieved only by first mixing the sol at high water content compositions that favor nanocrystal formation and then - after a certain time - lowering by freeze-drying the water to levels favoring the formation of FAU. Cryogenic transmission electron microscopy and small angle X-ray scattering from representative optically clear and colloidally stable precursor sols (aged and crystallized at ambient temperature) reveal the formation of amorphous aggregates before the detection of crystals, in agreement with earlier findings and an existing model for the aggregative growth of the zeolite MFI. The presence of these amorphous aggregates coincides with the aforementioned state of sol that preserves the original trajectory towards nano-crystals after the pronounced reduction of water content by freeze-drying. If water reduction by freeze-drying is applied earlier (before the detection of amorphous aggregates), the sol follows the low water content trajectory towards larger crystals. Despite this memory effect, the sol at this stage is still agnostic towards FAU or EMT formation, the relative content of which is dominantly determined by the final water content. These findings demonstrate that it is possible to combine the effects of pre-and post-nucleation sol composition to steer crystal size and crystal structure, respectively. They confirm precursor

Hydrothermally grown zeolite crystals

International Nuclear Information System (INIS)

Durrani, S.K.; Qureshi, A.H.; Hussain, M.A.; Qazi, N.K.

2009-01-01

The aluminium-deficient and ferrosilicate zeolite-type materials were synthesized by hydrothermal process at 150-170 degree C for various periods of time from the mixtures containing colloidal reactive silica, sodium aluminate, sodium hydroxide, iron nitrate and organic templates. Organic polycation templates were used as zeolite crystal shape modifiers to enhance relative growth rates. The template was almost completely removed from the zeolite specimens by calcination at 550 degree C for 8h in air. Simultaneous thermogravimetric (TG) and differential thermal analysis (DTA) was performed to study the removal of water molecules and the amount of organic template cations occluded inside the crystal pore of zeolite framework. The 12-13% weight loss in the range of (140-560 degree C) was associated with removal of the (C/sub 3/H/sub 7/)/sub 4/ N+ cation and water molecules. X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) techniques were employed to study the structure, morphology and surface features of hydrothermally grown aluminium-deficient and ferrosilicate zeolite-type crystals. In order to elucidate the mode of zeolite crystallization the crystallinity and unit cell parameters of the materials were determined by XRD, which are the function of Al and Fe contents of zeolites. (author)

Cation composition and oxygen content dependence of crystal structure and T sub c for Tl sub 2 sub - sub x Ba sub 2 Ca sub 2 Cu sub 3 sub + sub z O sub y

CERN Document Server

Idemoto, Y; Koura, N; Kamiyama, T; Oikawa, K; Izumi, F

2003-01-01

Tl sub 2 sub - sub x Ba sub 2 Ca sub 2 Cu sub 3 sub + sub z O sub y (Tl-2223 system) superconducting oxides with various Tl contents and Cu contents were prepared. We investigated the relation between crystal structure and superconducting property dependence of Tl and Cu content. First, we obtained an almost single-phase material at a Tl content 2-x = 1.7 and the Tl-2223 phase remained the main phase in the region of 2 - x >= 0.631 of Tl sub 2 sub - sub x Ba sub 2 Ca sub 2 Cu sub 3 O sub y. T sub c was about 120 K for the Tl-2223 in a wide range of 0.631 <= 2 - x <= 1.761. Second, we obtained a single-phase at 2 - x = 1.777 and Cu content 3 + z = 3.284 of Tl sub 2 sub - sub x Ba sub 2 Ca sub 2 Cu sub 3 sub + sub z O sub y. The T sub c (zero) dependence of Cu/Tl ratio, showed a maximum value of 122 K at Cu/Tl ratio = 2.026. Based on results of crystal structure refinements by powder neutron diffraction, it was found that the change in bond length and angle dependence of average Cu valence were similar fo...

Effect of Co content on structure and magnetic behaviors of high induction Fe-based amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Roy, Rajat K., E-mail: rajat@nmlindia.org; Panda, Ashis K.; Mitra, Amitava

2016-11-15

The replacement of Fe with Co is investigated in the (Fe{sub 1−x}Co{sub x}){sub 79}Si{sub 8.5}B{sub 8.5}Nb{sub 3}Cu{sub 1} (x=0, 0.05, 0.2, 0.35, 0.5) amorphous alloys. The alloys are synthesized in the forms of ribbons by single roller melt spinning technique, and the structural and magnetic properties of annealed ribbons are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), B–H curve tracer, respectively. All as-cast alloys are structurally amorphous, however, their magnetic properties are varying with Co addition. The Co addition within 5–20 at% results in moderate thermal stability, saturation induction, Curie temperature and lowest coercivity, while 35 at% Co causes highest saturation induction, coercivity, Curie temperature and lowest thermal stability. On devitrification, the magnetic properties change with the generation of α-FeCo nanocrystallites and (FeCo){sub 23}B{sub 6}, Fe{sub 2}B phases during primary and secondary crystallization stages, respectively. A small amount Co is advantageous for maintaining finer nanocrystallites in amorphous matrix even after annealing at 600 °C, leading to high saturation magnetization (>1.5 T) and low coercivity (~35 A/m). The improved magnetic properties at elevated temperatures indicate these alloys have a potential for high frequency transformer core applications. - Highlights: • The structural and magnetic behaviors of Fe based amorphous alloys have been investigated with the effect of Co content. • The Co has no adverse effect on amorphization of alloys. • A small amount Co causes the superior improvement of magnetic properties at elevated temperatures. • Therefore, it is important not only for academic research but also for industrial applied research.

Shrink, twist, ripple and melt: Studies of frustrated liquid crystals

Science.gov (United States)

Fernsler, Jonathan G.

Complex structures can arise out of a simple system with more than one competing influence on its behavior. The protypical example of this is the two-dimensional triangular lattice Ising model. The ferromagnetic model has two simple degenerate ground states of all spins up or down, but the antiferromagnetic model is a frustrated system. Its geometry does not allow satisfaction of the antiferro condition everywhere, which produces complex ordered structures with dimerization of the spins [1]. Without frustration, the complex structures and phase behavior are lost. All of the topics discussed in this thesis concern smectic liquid crystals. Liquid crystals are perhaps uniquely adept at manifesting frustrated phases. Their combination of periodicity in one or more dimensions allows ordered structures, yet their fluid nature in remaining dimensions allows creation of defects and extraordinarily complex structures in ways that a normal crystal could not tolerate. Liquid crystals contain a huge menagerie of frustrated phases and effects including the polarization modulated [2], vortex lattice [3], twist grain boundary [4], and blue [5] phases, as well as frustrated structures such as cholesteric or SmC* helix unwinding [6], defect lattices in thin films [7], and bend melted grain boundary defects [8], arising from boundary conditions and field effects. In this thesis, we study four liquid crystal systems that show unusual phase behavior or complex structures, deriving from the effects of frustration. Frustration, despite some human prejudices against the word, leaves nature all the more interesting and beautiful.

Role of crystal arrangement on the mechanical performance of enamel.

Science.gov (United States)

An, Bingbing; Wang, Raorao; Zhang, Dongsheng

2012-10-01

The superior mechanical properties of enamel, such as excellent penetration and crack resistance, are believed to be related to the unique microscopic structure. In this study, the effects of hydroxyapatite (HAP) crystallite orientation on the mechanical behavior of enamel have been investigated through a series of multiscale numerical simulations. A micromechanical model, which considers the HAP crystal arrangement in enamel prisms, the hierarchical structure of HAP crystals and the inelastic mechanical behavior of protein, has been developed. Numerical simulations revealed that, under compressive loading, plastic deformation progression took place in enamel prisms, which is responsible for the experimentally observed post-yield strain hardening. By comparing the mechanical responses for the uniform and non-uniform arrangement of HAP crystals within enamel prisms, it was found that the stiffness for the two cases was identical, while much greater energy dissipation was observed in the enamel with the non-uniform arrangement. Based on these results, we propose an important mechanism whereby the non-uniform arrangement of crystals in enamel rods enhances energy dissipation while maintaining sufficient stiffness to promote fracture toughness, mitigation of fracture and resistance to penetration deformation. Further simulations indicated that the non-uniform arrangement of the HAP crystals is a key factor responsible for the unique mechanical behavior of enamel, while the change in the nanostructure of nanocomposites could dictate the Young's modulus and yield strength of the biocomposite. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of Cu content on wear resistance and mechanical behavior of Ti-Cu binary alloys

Science.gov (United States)

Yu, Feifei; Wang, Hefeng; Yuan, Guozheng; Shu, Xuefeng

2017-04-01

Arc melting with nonconsumable tungsten electrode and water-cooled copper crucible was used to fabricate Ti-Cu binary alloys with different Cu contents in an argon atmosphere. The compositions and phase structures of the fabricated alloys were investigated by glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). Nanoindentation tests through continuous stiffness measurement were then performed at room temperature to analyze the mechanical behaviors of the alloys. Results indicated that the composition of each Ti-Cu binary alloy was Ti(100- x) Cu x ( x = 43, 60, 69, and 74 at.%). The XRD analysis results showed that the alloys were composed of different phases, indicating that different Cu contents led to the variations in alloy hardness. The wear tests results revealed that elemental Cu positively affects the wear resistance properties of the Ti-Cu alloys. Nanoindentation testing results showed that the moduli of the Ti-Cu alloys were minimally changed at increasing Cu content, whereas their hardness evidently increased according to the wear test results.

Structure analysis on synthetic emerald crystals

Science.gov (United States)

Lee, Pei-Lun; Lee, Jiann-Shing; Huang, Eugene; Liao, Ju-Hsiou

2013-05-01

Single crystals of emerald synthesized by means of the flux method were adopted for crystallographic analyses. Emerald crystals with a wide range of Cr3+-doping content up to 3.16 wt% Cr2O3 were examined by X-ray single crystal diffraction refinement method. The crystal structures of the emerald crystals were refined to R 1 (all data) of 0.019-0.024 and w R 2 (all data) of 0.061-0.073. When Cr3+ substitutes for Al3+, the main adjustment takes place in the Al-octahedron and Be-tetrahedron. The effect of substitution of Cr3+ for Al3+ in the beryl structure results in progressively lengthening of the Al-O distance, while the length of the other bonds remains nearly unchanged. The substitution of Cr3+ for Al3+ may have caused the expansion of a axis, while keeping the c axis unchanged in the emerald lattice. As a consequence, the Al-O-Si and Al-O-Be bonding angles are found to decrease, while the angle of Si-O-Be increases as the Al-O distance increases during the Cr replacement.

Neutralization of Hydroxide Ion in Melt-Grown NaCl Crystals

Science.gov (United States)

Otterson, Dumas A.

1961-01-01

Many recent studies of solid-state phenomena, particularly in the area of crystal imperfections, have involved the use of melt-grown NaCl single crystals. Quite often trace impurities in these materials have had a prominent effect on these phenomena. Trace amounts of hydroxide ion have been found in melt-grown NaCl crystals. This paper describes a nondestructive method of neutralizing the hydroxide ion in such crystals. Crystals of similar hydroxide content are maintained at an elevated temperature below the melting point of NaCl in a flowing atmosphere containing. dry hydrogen chloride. Heat treatment is continued until an analysis of the test specimens shows no excess hydroxide ion. A colorimetric method previously described4 is used for this analysis.

Effect of Sn additive on the structure and crystallization kinetics in Ge–Se alloy

Energy Technology Data Exchange (ETDEWEB)

Abd-Elrahman, M.I., E-mail: mostafaia11@yahoo.com; Hafiz, M.M.; Abdelraheem, A.M.; Abu-Sehly, A.A.

2016-08-05

The structure of Ge{sub 20}Se{sub 80−x}Snx glassy alloys and crystallization phases are identified using the X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The glass transition kinetics and the crystallization mechanism of the system are studied using Differential Scanning Calorimeter (DSC) under non-isothermal condition. The results reveal that glass transition temperature (Tg) increases with increasing Sn content which is attributed to the increase in the coordination number. The increase of the glass transition activation energy (Eg) with increasing Sn content is attributed to the decrease in the internal energy of the system as Sn increases. The compositional dependence of both glass forming ability and thermal stability are studied. From the experimental data, the thermal stability parameter (S) is found to be maximum for Ge{sub 20}Se{sub 78}Sn{sub 2} alloy, which indicates that this alloy is thermally more stable in the composition range under investigation. The effect of composition on the crystallization mechanism is discussed using different kinetic models. The crystallization activation energy (Ec) decreases with increasing Sn. This is attributed to the addition of Sn increases the tendency of crystallization. The calculated values of Avrami exponent (n) indicates the crystallization process occurs in one-and two dimensions for Sn is less than or equals 12 at%, respectively. - Highlights: • Glass and crystallization transitions in Ge{sub 20}Se{sub 80−x}Sn{sub x} candidate for devices. • The addition of Sn increases the tendency of Ge-Se alloy to crystallization. • The glass forming ability and thermal stability increase as Sn decreases. • The dimension of the crystals growth is one or two depending on the Sn content.

Lyotropic chromonic liquid crystals: From viscoelastic properties to living liquid crystals

Science.gov (United States)

Zhou, Shuang

Lyotropic chromonic liquid crystal (LCLC) represents a broad range of molecules, from organic dyes and drugs to DNA, that self-assemble into linear aggregates in water through face-to-face stacking. These linear aggregates of high aspect ratio are capable of orientational order, forming, for example nematic phase. Since the microscopic properties (such as length) of the chromonic aggregates are results of subtle balance between energy and entropy, the macroscopic viscoelastic properties of the nematic media are sensitive to change of external factors. In the first part of this thesis, by using dynamic light scattering and magnetic Frederiks transition techniques, we study the Frank elastic moduli and viscosity coefficients of LCLC disodium cromoglycate (DSCG) and sunset yellow (SSY) as functions of concentration c , temperature T and ionic contents. The elastic moduli of splay (K1) and bend (K3) are in the order of 10pN, about 10 times larger than the twist modulus (K2). The splay modulus K1 and the ratio K1/K3 both increase substantially as T decreases or c increases, which we attribute to the elongation of linear aggregates at lower T or higher c . The bend viscosity is comparable to that of thermotropic liquid crystals, while the splay and twist viscosities are several orders of magnitude larger, changing exponentially with T . Additional ionic additives into the system influence the viscoelastic properties of these systems in a dramatic and versatile way. For example, monovalent salt NaCl decreases bend modulus K3 and increases twist viscosity, while an elevated pH decreases all the parameters. We attribute these features to the ion-induced changes in length and flexibility of building units of LCLC, the chromonic aggregates, a property not found in conventional thermotropic and lyotropic liquid crystals form by covalently bound units of fixed length. The second part of the thesis studies a new active bio-mechanical hybrid system called living liquid crystal

Influence of crystal shapes on radiative fluxes in visible wavelength: ice crystals randomly oriented in space

Directory of Open Access Journals (Sweden)

P. Chervet

1996-08-01

Full Text Available Radiative properties of cirrus clouds are one of the major unsolved problems in climate studies and global radiation budget. These clouds are generally composed of various ice-crystal shapes, so we tried to evaluate effects of the ice-crystal shape on radiative fluxes. We calculated radiative fluxes of cirrus clouds with a constant geometrical depth, composed of ice crystals with different shapes (hexagonal columns, bullets, bullet-rosettes, sizes and various concentrations. We considered ice particles randomly oriented in space (3D case and their scattering phase functions were calculated by a ray-tracing method. We calculated radiative fluxes for cirrus layers for different microphysical characteristics by using a discrete-ordinate radiative code. Results showed that the foremost effect of the ice-crystal shape on radiative properties of cirrus clouds was that on the optical thickness, while the variation of the scattering phase function with the ice shape remained less than 3% for our computations. The ice-water content may be a better choice to parameterize the optical properties of cirrus, but the shape effect must be included.

A study on the effect of silicon content on mechanical properties

International Nuclear Information System (INIS)

Kwon, C.T.; Nam, T.W.; Lee, S.I.

1978-01-01

In Al-Si alloy, the variation of mechanical properties with silicon contents was investigated the silicon content being varied from 5% to 25%, and the effects of additives and refining elements were also studied. The results obtained are as follows: 1) Sodium treatment made the primary silicon crystals refined and spheroidized, and made the matrix structure intensified. The effect of P treatment on refining primary silicon crystals was greater then that of Na. 2) Tensile strength showed the maximum value at near the eutectic composition and was improved considerably by addition of Mg and treatment with Na. 3) The variation of matrix hardness with silicon contents was not perceptible and the hardness was improved by addition of Mg and treatment with Na. (author)

Structural changes in a clay-containing nanocomposite with a different moisture content caused by its deformation

International Nuclear Information System (INIS)

Fajtel'son, E.A.; Glaskova, T.I.; Korkhovm, V.P.; Aniskevich, A.N.

2010-01-01

This paper presents the results of an investigation of the properties of a clay-containing nanocomposite with an epoxy binder under moisture-temperature and mechanical action. It has been established that whatever the moisture content, the nanocomposite crystallizes under the thermomechanical action (upon reaching the glasstransition temperature). When the nanocomposite is heated to 70 C, the restructuring process is reversible, and its heating to above 150 C leads to its amorphization. The presence of clay nanoparticles (up to 6 mass percent) does not influence the temperature of structural transitions of the nanocomposite and does not cause a substantial strengthening effect. The sorbed moisture plasticizes the nanocomposite and decreases its glasstransition temperature by 10 C. The specific features of the thermomechanical behavior of nanocomposites upon their tensile prestrain or creep are due to the formation of an oriented structure. Their crystallization begins at lower temperatures and with a higher degree of crystallinity than that of unloaded nanostructures. (authors)

Tunable bandgap in hybrid perovskite CH3NH3Pb(Br3−yXy single crystals and photodetector applications

Directory of Open Access Journals (Sweden)

L. Wang

2016-04-01

Full Text Available We report the synthesis of CH3NH3Pb(Br3−yXy (X=Cl and I single crystals via a stepwise temperature control approach. High-quality CH3NH3Pb(Br3−yXy crystals with a tunable bandgap from 1.92eV to 2.53eV have been prepared successfully in this way. And further experiments revealed the influence of halogen content and preparation temperature on the structural and optical properties of these crystals. It is observed that chlorine can lower the critical nucleation energy, which results in crystallizing at lower temperature with the chlorine content increasing, while the nucleation energy increases slowly with increasing iodine content. Moreover, in contrast to Frank–van der Merwe growth with low heating rate, high heating rate leads to a mass of small size single crystals and Stranski-Krastanov growth. The single crystals with tunable band gap and impressive characteristics enable us to fabricate high performance photodetectors for different wavelengths.

Development of high-performance X-ray transparent crystallization plates for in situ protein crystal screening and analysis

Energy Technology Data Exchange (ETDEWEB)

Soliman, Ahmed S. M.; Warkentin, Matthew [Cornell University, Ithaca, New York (United States); Apker, Benjamin [MiTeGen LLC, Ithaca, New York (United States); Thorne, Robert E., E-mail: ret6@cornell.edu [Cornell University, Ithaca, New York (United States); MiTeGen LLC, Ithaca, New York (United States)

2011-07-01

An optically, UV and X-ray transparent crystallization plate suitable for in situ analysis has been developed. The plate uses contact line pinning rather than wells to confine the liquids. X-ray transparent crystallization plates based upon a novel drop-pinning technology provide a flexible, simple and inexpensive approach to protein crystallization and screening. The plates consist of open cells sealed top and bottom by thin optically, UV and X-ray transparent films. The plates do not need wells or depressions to contain liquids. Instead, protein drops and reservoir solution are held in place by rings with micrometre dimensions that are patterned onto the bottom film. These rings strongly pin the liquid contact lines, thereby improving drop shape and position uniformity, and thus crystallization reproducibility, and simplifying automated image analysis of drop contents. The same rings effectively pin solutions containing salts, proteins, cryoprotectants, oils, alcohols and detergents. Strong pinning by rings allows the plates to be rotated without liquid mixing to 90° for X-ray data collection or to be inverted for hanging-drop crystallization. The plates have the standard SBS format and are compatible with standard liquid-handling robots.

Fragmentation, nucleation and migration of crystals and bubbles in the Bishop Tuff rhyolitic magma

Energy Technology Data Exchange (ETDEWEB)

Gualda, G.; Cook, D.L.; Chopra, R.; Qin, L.; Anderson, A.T.; Rivers, M. (UC)

2010-12-07

The Bishop Tuff (USA) is a large-volume, high-silica pyroclastic rhyolite. Five pumice clasts from three early stratigraphic units were studied. Size distributions were obtained using three approaches: (1) crushing, sieving and winnowing (reliable for crystals >100 {micro}m); (2) microscopy of 1 mm{sup 3} fragments (preferable for crystals <100 {micro}m); and (3) computerised X-ray microtomography of {approx}1 cm{sup 3} pumice pieces. Phenocryst fragments coated with glass are common, and the size distributions for all crystals are concave-upward, indicating that crystal fragmentation is an important magmatic process. Three groups are recognised, characterised by: (1) high-density (0.759-0.902 g cm{sup -3}), high-crystal content (14.4-15.3 wt.%) and abundant large crystals (>800 {micro}m); concave-downward size distributions for whole crystals indicate late-stage growth with limited nucleation, compatible with the slow cooling of a large, gas-saturated, stably stratified magma body; (2) low-density (0.499 g cm{sup -3}), low-crystal content (6.63 wt.%) and few large crystals; the approximately linear size distribution reveals that nucleation was locally important, perhaps close to the walls; and (3) intermediate characteristics in all respects. The volumetric fraction of bubbles inversely correlates with the number of large crystals. This is incompatible with isobaric closed-system crystallisation, but can be explained by sinking of large crystals and rise of bubbles in the magma.

Behavior change techniques in popular alcohol reduction apps: content analysis.

Science.gov (United States)

Crane, David; Garnett, Claire; Brown, James; West, Robert; Michie, Susan

2015-05-14

Mobile phone apps have the potential to reduce excessive alcohol consumption cost-effectively. Although hundreds of alcohol-related apps are available, there is little information about the behavior change techniques (BCTs) they contain, or the extent to which they are based on evidence or theory and how this relates to their popularity and user ratings. Our aim was to assess the proportion of popular alcohol-related apps available in the United Kingdom that focus on alcohol reduction, identify the BCTs they contain, and explore whether BCTs or the mention of theory or evidence is associated with app popularity and user ratings. We searched the iTunes and Google Play stores with the terms "alcohol" and "drink", and the first 800 results were classified into alcohol reduction, entertainment, or blood alcohol content measurement. Of those classified as alcohol reduction, all free apps and the top 10 paid apps were coded for BCTs and for reference to evidence or theory. Measures of popularity and user ratings were extracted. Of the 800 apps identified, 662 were unique. Of these, 13.7% (91/662) were classified as alcohol reduction (95% CI 11.3-16.6), 53.9% (357/662) entertainment (95% CI 50.1-57.7), 18.9% (125/662) blood alcohol content measurement (95% CI 16.1-22.0) and 13.4% (89/662) other (95% CI 11.1-16.3). The 51 free alcohol reduction apps and the top 10 paid apps contained a mean of 3.6 BCTs (SD 3.4), with approximately 12% (7/61) not including any BCTs. The BCTs used most often were "facilitate self-recording" (54%, 33/61), "provide information on consequences of excessive alcohol use and drinking cessation" (43%, 26/61), "provide feedback on performance" (41%, 25/61), "give options for additional and later support" (25%, 15/61) and "offer/direct towards appropriate written materials" (23%, 14/61). These apps also rarely included any of the 22 BCTs frequently used in other health behavior change interventions (mean 2.46, SD 2.06). Evidence was mentioned by 16

Reduced nicotine content cigarette advertising: How false beliefs and subjective ratings affect smoking behavior.

Science.gov (United States)

Mercincavage, Melissa; Saddleson, Megan L; Gup, Emily; Halstead, Angela; Mays, Darren; Strasser, Andrew A

2017-04-01

Tobacco advertising can create false beliefs about health harms that are reinforced by product design features. Reduced nicotine content (RNC) cigarettes may reduce harm, but research has not addressed advertising influences. This study examined RNC cigarette advertising effects on false harm beliefs, and how these beliefs - along with initial subjective ratings of RNC cigarettes - affect subsequent smoking behaviors. We further explored whether subjective ratings moderate associations between false beliefs and behavior. Seventy-seven daily, non-treatment-seeking smokers (66.2% male) participated in the first 15days of a randomized, controlled, open-label RNC cigarette trial. Participants viewed an RNC cigarette advertisement at baseline before completing a 5-day period of preferred brand cigarette use, followed by a 10-day period of RNC cigarette use (0.6mg nicotine yield). Participants provided pre- and post-advertisement beliefs, and subjective ratings and smoking behaviors for cigarettes smoked during laboratory visits. Viewing the advertisement increased beliefs that RNC cigarettes contain less nicotine and are healthier than regular cigarettes (p'saffected smoking behaviors. Significant interactions of strength and taste ratings with beliefs (p'ssmokers with less negative initial subjective ratings, greater false beliefs were associated with greater RNC cigarette consumption. Smokers may misconstrue RNC cigarettes as less harmful than regular cigarettes. These beliefs, in conjunction with favorable subjective ratings, may increase product use. Copyright © 2017 Elsevier B.V. All rights reserved.

A study of the crystallization of ZrO

International Nuclear Information System (INIS)

Aguilar, D. H.; Torres-Gonzalez, L. C.; Torres-Martinez, L. M.; Lopez, T.; Quintana, P.

2001-01-01

ZrO(sub 2)-SiO(sub 2) sol-gel powders were produced using tetraethoxysilane (TEOS) and zirconium propoxide. After gellation, the ZrO(sub 2) crystallization process was investigated using X-ray diffraction (XRD), thermal analysis (DTA/TGA), and scanning electron microscopy (SEM). Fresh gels were amorphous. Thermal treatments were carried out from 100 to 1400 C for a total annealing time of 182 h. Tetragonal zirconia, (Z(t)) was the first phase to crystallize, between 300 and 500 C. Crystallization temperature was lower for zirconia-rich compositions, increasing as silica content was raised. DTA analysis showed that Z(t) crystallization occurred in two stages. Complete tetragonal-monoclinic zirconia transformation occurred near 1000 C, and was clearly observed only in ZrO(sub 2)-rich compositions ( and gt;80%). Silica remains amorphous until 1200 C, when ZrSiO(sub 4) formation took place. A metastable sol-gel phase diagram was proposed to show the crystallization process between 100 and 1400 C

Crystallization characteristics of Mg-doped Ge2Sb2Te5 films for phase change memory applications

International Nuclear Information System (INIS)

Fu Jing; Shen Xiang; Nie Qiuhua; Wang Guoxiang; Wu Liangcai; Dai Shixun; Xu Tiefeng; Wang, R.P.

2013-01-01

Highlights: ► Mg-doped Ge 2 Sb 2 Te 5 (GST) phase change films with higher resistance and better thermal stability have been proposed. ► The increase of Mg content result in an enhancement in crystallization temperature, activation energy and electrical resistance. ► The proper Mg addition in GST can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase. ► The formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhancement thermal stability in Mg-doped GST films. - Abstract: Mg-doped Ge 2 Sb 2 Te 5 (GST) films with different Mg doping concentrations have been prepared, and their crystallization behavior, structure and electrical properties have been systematically investigated for phase-change memory applications. The results show that the addition of Mg into GST films could result in an enhancement in crystallization temperature, activation energy and electrical resistance compared with the conventional GST films, indicating that a good amorphous thermal stability. On the other hand, the proper Mg concentration ranging from 13.6 to 31.1 at.% can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase and suppress the formation of the hexagonal close-packed (hcp) crystalline phase. X-ray photoelectron spectra (XPS) further confirm that the formation of covalent Mg-Sb and Mg-Te bonds contribute to the enhanced thermal stability in Mg-doped GST films.

The Impact of Cognitive-Affective Content on Advertising Messages in Consumer Attitudes and Behavioral Intentions: The Dual Cognitive-Affective Model (DMAC)-Edición Única

OpenAIRE

Valdéz García, Carlos G.

2005-01-01

In advertising, two important theoretical approaches, cognitive and affective, explain how consumer attitudes and behavioral intentions are affected by message content. However, the effects of cognitive and affective content in a single advertising message in consumer attitudes and behaviors have been understudied. In vi this research, using the theoretical constructs of cognitive and affective approaches to explore the effects of their interaction in advertising messages wa...

Observation of Wigner crystal phase and ripplon-limited mobility behavior in monolayer CVD MoS2 with grain boundary

Science.gov (United States)

Chen, Jyun-Hong; Zhong, Yuan-Liang; Li, Lain-Jong; Chen, Chii-Dong

2018-06-01

Two-dimensional electron gas (2DEG) is crucial in condensed matter physics and is present on the surface of liquid helium and at the interface of semiconductors. Monolayer MoS2 of 2D materials also contains 2DEG in an atomic layer as a field effect transistor (FET) ultrathin channel. In this study, we synthesized double triangular MoS2 through a chemical vapor deposition method to obtain grain boundaries for forming a ripple structure in the FET channel. When the temperature was higher than approximately 175 K, the temperature dependence of the electron mobility μ was consistent with those in previous experiments and theoretical predictions. When the temperature was lower than approximately 175 K, the mobility behavior decreased with the temperature; this finding was also consistent with that of the previous experiments. We are the first research group to explain the decreasing mobility behavior by using the Wigner crystal phase and to discover the temperature independence of ripplon-limited mobility behavior at lower temperatures. Although these mobility behaviors have been studied on the surface of liquid helium through theories and experiments, they have not been previously analyzed in 2D materials and semiconductors. We are the first research group to report the similar temperature-dependent mobility behavior of the surface of liquid helium and the monolayer MoS2.

Observation of Wigner crystal phase and ripplon-limited mobility behavior in monolayer CVD MoS2 with grain boundary

KAUST Repository

Chen, Jyun-Hong

2018-03-12

Two-dimensional electron gas (2DEG) is crucial in condensed matter physics and is present on the surface of liquid helium and at the interface of semiconductors. Monolayer MoS2 of 2D materials also contains 2DEG in an atomic layer as field effect transistor (FET) ultrathin channel. In this study, we synthesized double triangular MoS₂ through a chemical vapor deposition method to obtain grain boundaries for forming a ripple structure in FET channel. When the temperature was higher than approximately 175 K, the temperature dependence of the electron mobility μ was consistent with those in previous experiments and theoretical predictions. When the temperature was lower than approximately 175 K, the mobility behavior decreased with the temperature; this finding was also consistent with that of the previous experiments. We are the first research group to explain the decreasing mobility behavior by using the Wigner crystal phase and to discover the temperature independence of ripplon-limited mobility behavior at lower temperatures. Although these mobility behaviors have been studied on the surface of liquid helium through theories and experiments, they have not previously analyzed in 2D materials and semiconductors. We are the first research group to report the similar temperature-dependent mobility behavior of the surface of liquid helium and the monolayer MoS₂.

Crystal-Size-Dependent Structural Transitions in Nanoporous Crystals: Adsorption-Induced Transitions in ZIF-8

KAUST Repository

Zhang, Chen

2014-09-04

© 2014 American Chemical Society. Understanding the crystal-size dependence of both guest adsorption and structural transitions of nanoporous solids is crucial to the development of these materials. We find that nano-sized metal-organic framework (MOF) crystals have significantly different guest adsorption properties compared to the bulk material. A new methodology is developed to simulate the adsorption and transition behavior of entire MOF nanoparticles. Our simulations predict that the transition pressure significantly increases with decreasing particle size, in agreement with crystal-size-dependent experimental measurements of the N2-ZIF-8 system. We also propose a simple core-shell model to examine this effect on length scales that are inaccessible to simulations and again find good agreement with experiments. This study is the first to examine particle size effects on structural transitions in ZIFs and provides a thermodynamic framework for understanding the underlying mechanism.

Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

Energy Technology Data Exchange (ETDEWEB)

Foteinopoulou, Stavroula [Iowa State Univ., Ames, IA (United States)

2003-01-01

In this dissertation, they have undertaken the challenge to understand the unusual propagation properties of the photonic crystal (PC). The photonic crystal is a medium where the dielectric function is periodically modulated. These types of structures are characterized by bands and gaps. In other words, they are characterized by frequency regions where propagation is prohibited (gaps) and regions where propagation is allowed (bands). In this study they focus on two-dimensional photonic crystals, i.e., structures with periodic dielectric patterns on a plane and translational symmetry in the perpendicular direction. They start by studying a two-dimensional photonic crystal system for frequencies inside the band gap. The inclusion of a line defect introduces allowed states in the otherwise prohibited frequency spectrum. The dependence of the defect resonance state on different parameters such as size of the structure, profile of incoming source, etc., is investigated in detail. For this study, they used two popular computational methods in photonic crystal research, the Finite Difference Time Domain method (FDTD) and the Transfer Matrix Method (TMM). The results for the one-dimensional defect system are analyzed, and the two methods, FDTD and TMM, are compared. Then, they shift their attention only to periodic two-dimensional crystals, concentrate on their band properties, and study their unusual refractive behavior. Anomalous refractive phenomena in photonic crystals included cases where the beam refracts on the ''wrong'' side of the surface normal. The latter phenomenon, is known as negative refraction and was previously observed in materials where the wave vector, the electric field, and the magnetic field form a left-handed set of vectors. These materials are generally called left-handed materials (LHM) or negative index materials (NIM). They investigated the possibility that the photonic crystal behaves as a LHM, and how this behavior relates

Crystal Nucleation and Crystal Growth and Mass Transfer in Internally Mixed Sucrose/NaNO3 Particles.

Science.gov (United States)

Ji, Zhi-Ru; Zhang, Yun; Pang, Shu-Feng; Zhang, Yun-Hong

2017-10-19

Secondary organic aerosols (SOA) can exist in a glassy or semisolid state under low relative humidity (RH) conditions, in which the particles show nonequilibrium kinetic characteristics with changing ambient RH. Here, we selected internally mixed sucrose/NaNO 3 droplets with organic to inorganic molar ratios (OIRs) of 1:8, 1:4, 1:2, and 1:1 as a proxy for multicomponent ambient aerosols to study crystal nucleation and growth processes and water transport under a highly viscous state with the combination of an RH-controlling system and a vacuum Fourier transform infrared (FTIR) spectrometer. The initial efflorescence RH (ERH) of NaNO 3 decreased from ∼45% for pure NaNO 3 droplets to ∼38.6 and ∼37.9% for the 1:8 and 1:4 sucrose/NaNO 3 droplets, respectively, while no crystallization of NaNO 3 occurred for the 1:2 and 1:1 droplets in the whole RH range. Thus, the addition of sucrose delayed the ERH and even completely inhibited nucleation of NaNO 3 in the mixed droplets. In addition, the crystal growth of NaNO 3 was suppressed in the 1:4 and 1:8 droplets most likely due to the slow diffusion of Na + and NO 3 - ions at low RH. Water uptake/release of sucrose/NaNO 3 particles quickly arrived at equilibrium at high RH, while the hygroscopic process was kinetically controlled under low RH. The half-time ratio between the liquid water content and the RH was used to describe the mass transfer behavior. For the 1:1 droplets, no mass limitation was observed with the ratio approaching to 1 when the RH was higher than 53%. The ratio increased 1 order of magnitude under an ultraviscous state with RH ranging from 53 to 15% and increased a further 1 order of magnitude at RH < 15% under a glassy state.

Effects of Cr 3+ impurity concentration on the crystallography of synthetic emerald crystals

Science.gov (United States)

Lee, Pei-Lun; Huang, Eugene; Lee, Jan-Shing; Yu, Shu-Cheng

2011-06-01

Flux method has been adopted for the synthesis of emerald crystals using PbO-V 2O 5 as a flux in order to study the crystallography of the synthetic crystals. In general, the hue of green color of emerald deepens with the addition of Cr 3+. The molar volume of the synthesized crystals was found to increase with the incorporation of Cr 2O 3 dopant. The substitution of Cr 3+ for Al 3+ in the octahedral sites of beryl results in the expansion of a-axis, while c-axis remains nearly unchanged. The maximum Cr 2O 3-content allowed in the crystal lattice of emerald has been found to be about 3.5 wt%. When the doping Cr 2O 3-content exceeds 3.5 wt%, a significant anomaly in lattice parameters starts to take place, accompanying the precipitation of an unknown phase in the emerald matrix.

Exploring the Progression in Preservice Chemistry Teachers' Pedagogical Content Knowledge Representations: The Case of "Behavior of Gases"

Science.gov (United States)

Adadan, Emine; Oner, Diler

2014-01-01

This multiple case study investigated how two preservice chemistry teachers' pedagogical content knowledge (PCK) representations of behavior of gases progressed in the context of a semester-long chemistry teaching methods course. The change in the participants' PCK components was interpreted with respect to the theoretical PCK learning…

Relaxor properties of barium titanate crystals grown by Remeika method

Science.gov (United States)

Roth, Michel; Tiagunov, Jenia; Dul'kin, Evgeniy; Mojaev, Evgeny

2017-06-01

Barium titanate (BaTiO3, BT) crystals have been grown by the Remeika method using both the regular KF and mixed KF-NaF (0.6-0.4) solvents. Typical acute angle "butterfly wing" BT crystals have been obtained, and they were characterized using x-ray diffraction, scanning electron microscopy (including energy dispersive spectroscopy), conventional dielectric and acoustic emission methods. A typical wing has a triangular plate shape which is up to 0.5 mm thick with a 10-15 mm2 area. The plate has a (001) habit and an atomically smooth outer surface. Both K+ and F- solvent ions are incorporated as dopants into the crystal lattice during growth substituting for Ba2+ and O2- ions respectively. The dopants' distribution is found to be inhomogeneous, their content being almost an order of magnitude higher (up to 2 mol%) at out surface of the plate relatively to the bulk. A few μm thick surface layer is formed where a multidomain ferroelectric net is confined between two≤1 μm thick dopant-rich surfaces. The layer as a whole possess relaxor ferroelectric properties, which is apparent from the appearance of additional broad maxima, Tm, in the temperature dependence of the dielectric permittivity around the ferroelectric phase transition. Intense acoustic emission responses detected at temperatures corresponding to the Tm values allow to observe the Tm shift to lower temperatures at higher frequencies, or dispersion, typical for relaxor ferroelectrics. The outer surface of the BT wing can thus serve as a relaxor thin film for various electronic application, such as capacitors, or as a substrate for BT-based multiferroic structure. Crystals grown from KF-NaF fluxes contain sodium atoms as an additional impurity, but the crystal yield is much smaller, and while the ferroelectric transition peak is diffuse it does not show any sign of dispersion typical for relaxor behavior.

Kinetic coefficients in isotopically disordered crystals

International Nuclear Information System (INIS)

Zhernov, Arkadii P; Inyushkin, Alexander V

2002-01-01

Peculiarities of the behavior of kinetic coefficients, like thermal conductivity, electric conductivity, and thermoelectric power, in isotopically disordered materials are reviewed in detail. New experimental and theoretical results on the isotope effects in the thermal conductivity of diamond, Ge, and Si semiconductors are presented. The suppression effect of phonon-drag thermopower in the isotopically disordered Ge crystals is discussed. The influence of dynamic and static crystal lattice deformations on the electric conductivity of metals as well as on the ordinary phonon spectrum deformations is considered. (reviews of topical problems)

Effect of sucrose polyesters on crystallization rate of vegetable ghee: solid fat content study

Directory of Open Access Journals (Sweden)

Ibrahim Nasir, Mohammad

2003-12-01

Full Text Available Crystallization rate of partial hydrogenated blend of soybean oil and cottonseed oil used for making vegetable ghee (vanaspati was investigated, by solid fat content (SFC using pulsed nuclear magnetic resonance (p-NMR. The effects of adding sucrose fatty acid esters or sucrose polyesters (SPE on the crystallization rate of the blend fat were studied. Sucrose tetrastearate DK ester F-10 (stearate 70% - palmitate 30% was added to the fat at different concentration, namely 0.5% and 1.0%. Blank sample and sample containing 0.5% and 1.0% DK ester F-10 / (DK F-10 were chosen to measure the change in SFC at constant temperature of 15ºC for a period of 25 hr. Five determinations of SFC were taken to the fat samples during the 25 hr i.e. 2,5,9,13 and 25th hr. SFC vs. time of crystallization of the three samples showed continuous increasing in SFC in all samples during the 25 hr, with sharp increasing at the first two hours. Samples containing 0.0% and 0.5% DK F-10, showed no significant difference in SFC during the first thirteen hours, while sample containing 1.0% DK F-10, showed higher SFC than the other two samples, through out the period. The amount of SFC for 1.0% DK F-10 sample at the 13th hour is equal to the SFC of the blank (0.0% sample at the 25th hour. Melting point of the same samples increased with the increasing DK F-10 concentration in the fat samples. The results of SFC make it sure that the addition of 1.0% DK F- 10 will shorten the time required for the crystallization of vegetable ghee while the addition of 0.5% will not have significant effect.Se ha investigado, mediante el contenido en grasa sólida (SFC por resonancia magnética nuclear pulsada (p-NMR, la velocidad de cristalización de mezcla de aceite de la soja y aceite de semilla del algodón parcialmente hidrogenada utilizada en la elaboración de ghee vegetal (vanaspati. Se han estudiado los efectos de añadir ésteres de sacarosa de ácidos grasos o poliésteres de

CRYSTAL-QUASICHEMICAL ANALYSIS OF DEFECT SUBSYSTEM OF DOPED PbTe: Sb CRYSTALS AND Pb-Sb-Te SOLID SOLUTIONS

Directory of Open Access Journals (Sweden)

D.M. Freik

2014-05-01

Full Text Available Within crystalquasichemical formalism models of point defects of crystals in the Pb-Sb-Te system were specified. Based on proposed crystalquasichemical formulae of antimony doped crystals PbTe:Sb amphoteric dopant effect was explained. Mechanisms of solid solution formation for РbТе-Sb2Те3: replacement of antimony ions lead sites  with the formation of cation vacancies  (I or neutral interstitial tellurium atoms  (II were examined. Dominant point defects in doped crystals PbTe:Sb and РbТе-Sb2Те3 solid solutions based on p-PbTe were defined. Dependences of concentration of dominant point defects, current carriers and Hall concentration on content of dopant compound and the initial deviation from stoichiometry in the basic matrix were calculated.

Lasing in liquid crystal thin films

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)], E-mail: palto@online.ru

2006-09-15

A lasing condition is formulated in matrix form for optically anisotropic thin films. Lasing behavior of liquid-crystal slabs is analyzed. In particular, it is shown that if the spatial extent of a liquid crystal slab is much larger than its thickness, then laser emission is feasible not only along the normal to the slab, but also in the entire angular sector. The generated laser light can be observed experimentally as a spot or as concentric rings on a screen. The lowest lasing threshold corresponds to in-plane sliding modes leaking into the substrate. The feedback required for lasing is provided by reflection from the interfaces, rather than edges, of the liquid-crystal slab operating as a planar Fabry-Perot cavity. For cholesteric liquid crystals, it is shown that energy loss to the sliding modes leaking into the substrates and escaping through their edges is a key factor that limits the efficiency of band-edge emission along the normal to the slab.

Neutrons and the crystal ball experiments

International Nuclear Information System (INIS)

Alyea, J.; Grosnick, D.; Koetke, D.; Manweiler, R.; Spinka, H.; Stanislaus, S.

1997-01-01

The Crystal Ball detector, as originally constructed, consisted of a set of 672 optically-isolated NaI crystals, forming an approximately spherical shell and each crystal viewed by a photomultiplier, a charged-particle tracker within the NaI shell, and two endcaps to cover angles close to two colliding beams. The detector geometry subtends a solid angle of about 93% of 4π st (20 degree le θ le 160degree and 0degree le φ le 360degree) from the center. The Crystal Ball detector was used for two long series of experiments at the e + e - colliding beam accelerators SPEAR [1, 2, 3, 4] at SLAC and DORIS [5, 6, 7, 8] at DESY. A new set of measurements using the Crystal Ball detector is planned at the Brookhaven National Laboratory Alternating Gradient Synchrotrons (BNL AGS). These new experiments will use the 672 NaI crystals from the original detector, but neither the tracker nor endcaps. The ''Crystal Ball'' in this note will refer only to the set of NaI crystals. Initially, the reactions to be studied will include π - pr a rrow neutrals with pion beam momenta approximately400-750 MeV/c and K - pr a rrow neutrals with kaon beam momenta approximately600-750 MeV/c. Each of these reactions will include a neutron in the final state. whereas the fraction of e + e - interactions with neutrons at SLAC or DESY was quite small. Consequently, there is relatively little experience understanding the behavior of neutrons in the Crystal Ball

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.

Luminescent properties of Y3Al5−xGaxO12:Ce crystals

International Nuclear Information System (INIS)

Zorenko, Yu.; Zorenko, T.; Malinowski, P.; Sidletskiy, O.; Neicheva, S.

2014-01-01

Absorption, luminescent and scintillation properties of Ce 3+ doped Y 3 Al 5−x Ga x O 12 crystals with Ga content in the x=1–5 range were investigated in this work and compared with the properties of YAG:Ce crystals. Apart from the traditional spectral methods (absorption, cathodoluminescence and light yield measurements), the intrinsic and Ce 3+ related luminescence of Y 3 Al 5−x Ga x O 12 :Ce solid-solution were also investigated using the luminescent spectroscopy under excitation by synchrotron radiation in the 3.7–25 eV range. We show that the optical properties Y 3 Al 5−x Ga x O 12 :Ce garnets monotonically change with increasing the Ga content in the x=0–3 range due to preferable localization of Ga ions in the tetrahedral position of the garnet lattice. At the highest Ga concentration (x>3) the deviation of the optical properties of Y 3 Al 5−x Ga x O 12 :Ce garnets is observed from the respective properties of these crystals with Ga content in the x=0–3 range due to occupation by Ga ions of the octahedral position in the garnet host. - Highlights: • Different dependence of optical properties of Y 3 Al 5−x Ga x O 12 :Ce crystals on Ga content in x=0–3 and 3–5 ranges. • Elimination of the luminescence of Y Al antisite defects in Y 3 Al 5−x Ga x O 12 :Ce crystals at x>2. • Significant improvement of the scintillation properties of Y 3 Al 5−x Ga x O 12 :Ce crystals at x=2 and 3 in comparison with YAG:Ce

Crystal chemistry and temperature behavior of the natural hydrous borate colemanite, a mineral commodity of boron

Science.gov (United States)

Lotti, Paolo; Gatta, G. Diego; Demitri, Nicola; Guastella, Giorgio; Rizzato, Silvia; Ortenzi, Marco Aldo; Magrini, Fabrizio; Comboni, Davide; Guastoni, Alessandro; Fernandez-Diaz, Maria Teresa

2018-05-01

Colemanite, CaB3O4(OH)3ṡH2O, is the most common hydrous Ca-borate, as well as a major mineral commodity of boron. In this study, we report a thorough chemical analysis and the low-temperature behavior of a natural sample of colemanite by means of a multi-methodological approach. From the chemical point of view, the investigated sample resulted to be relatively pure, its composition being very close to the ideal one, with only a minor substitution of Sr2+ for Ca2+. At about 270.5 K, a displacive phase transition from the centrosymmetric P21/ a to the acentric P21 space group occurs. On the basis of in situ single-crystal synchrotron X-ray (down to 104 K) and neutron diffraction (at 20 K) data, the hydrogen-bonding configuration of both the polymorphs and the structural modifications at the atomic scale at varying temperatures are described. The asymmetric distribution of ionic charges along the [010] axis, allowed by the loss of the inversion center, is likely responsible for the reported ferroelectric behavior of colemanite below the phase transition temperature.

Hydrothermal growth of PbSO4 (Anglesite) single crystal

International Nuclear Information System (INIS)

Kikuta, Ko-ichi; Yoneta, Yasuhito; Yogo, Toshinobu; Hirano, Shin-ichi

1994-01-01

Hydrothermal growth of single crystals of PbSO 4 , which is known as a natural mineral called anglesite, was investigated. Lead nitrate and nitric acid solutions were found to be useful for the growth of angle-site on the basis of the experimental results on the dissolution behavior. Relatively large euhedral single crystals bound by {210} and {101} planes were successfully grown in 1.5 mol/kg Pb(NO 3 ) 2 at 400degC and 100 MPa. Optical characterization revealed that the grown anglesite crystals can be useful for scintillators material. (author)

Effect of oxygen content on deformation mode and corrosion behavior in β-type Ti-Mo alloy

Energy Technology Data Exchange (ETDEWEB)

Min, Xiaohua, E-mail: minxiaohua@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Bai, Pengfei [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Emura, Satoshi; Ji, Xin [Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Cheng, Congqian; Jiang, Beibei [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Tsuchiya, Koichi [Research Center for Structural Materials, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

2017-01-27

This study examined microstructural characteristics and mechanical properties in a β-type Ti-15Mo alloy (mass%) with different oxygen contents, and their corrosion behavior in simulated physiological media. With increasing oxygen content from 0.1–0.5%, lattice parameter of parent β-phase increased from X-ray diffraction profiles, and spots of athermal ω-phase became weak and diffuse through transmission electron microscopy observations. {332}<113> twin density decreased with an increase in oxygen content from 0.1–0.3% based on electron backscattered diffraction analyses, and it became almost zero when further increased oxygen content up to 0.5%. The solute oxygen atoms led to both a transition of {332}<113> twinning to dislocation slip and a suppression of β-phase to ω-phase transformation. Room-temperature tensile testing of this alloy with oxygen content ranging from 0.1–0.5%, revealed that yield strength ranged from 420 MPa to 1180 MPa and that uniform elongation ranged from 47–0.2%. The oxygen-added alloys kept a low elastic modulus obtained from stress-strain curves, and exhibited good corrosion resistance in Ringer's solution from open-circuit potential and potentiodynamic polarization measurements. A desirable balance between mechanical properties and corrosion resistance is obtainable in this alloy as biomaterials through utilizing oxygen to control the deformation mode.

Irreversible dilation of NaCl contaminated lime-cement mortar due to crystallization cycles

International Nuclear Information System (INIS)

Lubelli, B.; Hees, R.P.J. van; Huinink, H.P.; Groot, C.J.W.P.

2006-01-01

The mechanism of damage occurring in NaCl contaminated materials has not been clarified yet. Apart from crystallization pressure, other hypotheses have been proposed to explain the cause of decay. Irreversible dilation has been observed in a few cases but has never been studied in a more systematic way. The aim of the research is to contribute to the modeling of this phenomenon. In the present paper the effect of NaCl on the hydric and hygric behavior of a lime-cement mortar is extensively studied. The results indicate that NaCl influences the hydric and hygric dilation behavior of the material. The material contaminated with NaCl shrinks during dissolution and dilates during crystallization of the salt. This dilation is irreversible and sufficient to damage the material after few dissolution/crystallization cycles. This behavior is not restricted to NaCl, but is observed in the presence of other salts as well (NaNO 3 and KCl). Outcomes of electron microscopy studies suggest that salts causing irreversible dilation tend to crystallize as layers on the pore wall

Crystal-field magnetic anisotropy of dilute dysprosium or erbium in yttrium single crystals

DEFF Research Database (Denmark)

Høg, J.; Touborg, P.

1974-01-01

Magnetization measurements have been performed between 1.3 and 300 K in fields up to 50 × 105 A/m in the a, b, and c directions of hcp crystals of pure Y and Y doped with 0.14-at.% Dy or 0.14-at.% Er, using the Faraday method and a vibrating-sample method. The characteristic behavior of both...

Threshold dose for behavioral discrimination of cigarette nicotine content in menthol vs. non-menthol smokers.

Science.gov (United States)

Perkins, Kenneth A; Kunkle, Nicole; Karelitz, Joshua L

2017-04-01

The lowest threshold content (or "dose") of nicotine discriminated in cigarettes may differ due to menthol preference. Menthol and non-menthol Spectrum research cigarettes differing in nicotine content were used to determine discrimination thresholds. Dependent smokers preferring menthol (n = 40) or non-menthol (n = 21) brands were tested on ability to discriminate cigarettes (matched for their menthol preference) with nicotine contents of 16-17, 11-12, 5, 2, and 1 mg/g, one per session, from an "ultra-low" cigarette with 0.4 mg/g. Controlled exposure to each cigarette was four puffs/trial, and the number of sessions was determined by the lowest nicotine content they could discriminate on >80% of trials (i.e., ≥5 of 6). We also assessed subjective perceptions and behavioral choice between cigarettes to relate them to discrimination responses. Controlling for Fagerstrom Test of Nicotine Dependence score, discrimination thresholds were more likely to be at higher nicotine content cigarettes for menthol vs. non-menthol smokers (p vs. 11 mg/g, respectively. Compared to the ultra-low, threshold and subthreshold (next lowest) cigarettes differed on most perceptions and puff choice, but menthol preference did not alter these associations. Notably, threshold cigarettes did, but subthreshold did not, increase choice over the ultra-low. Threshold for discriminating nicotine via smoking may be generally higher for menthol vs. non-menthol smokers. More research is needed to identify why menthol smoking is related to higher nicotine thresholds and to verify that cigarettes unable to be discriminated do not support reinforcement.

Registration of interstitial anions in irradiated MgO crystals

International Nuclear Information System (INIS)

Surzhikov, A.P.; Pogrebnyak, A.D.

1985-01-01

Possibility of application of positron annihilation for detection in oxides of rare earth metals with interstitial component of Frenkel anion defects is revealed. Magnesium oxide monocrystals with Ca, Si, Fe, Al impurity contents of 0.1 wt.% were investigated. These crystals were irradiated by X-rays (45 kV, 20 μA) and protons (10 MeV). It is shown that heating of magnesium oxide crystals irradiated by protons up to 700 K completely anneals F + -centers. In this case the component disappears inth the pulse distributon at xi=5.0; the subsequent crystal irradiation with X-ray does not lead to its reduction

Photonic Paint Developed with Metallic Three-Dimensional Photonic Crystals

Science.gov (United States)

Sun, Po; Williams, John D.

2012-01-01

This work details the design and simulation of an inconspicuous photonic paint that can be applied onto an object for anticounterfeit and tag, track, and locate (TTL) applications. The paint consists of three-dimensional metallic tilted woodpile photonic crystals embedded into a visible and infrared transparent polymer film, which can be applied to almost any surface. The tilted woodpile photonic crystals are designed with a specific pass band detectable at nearly all incident angles of light. When painted onto a surface, these crystals provide a unique reflective infra-red optical signature that can be easily observed and recorded to verify the location or contents of a package.

Crystallization and properties of a spodumene-willemite glass ceramic

International Nuclear Information System (INIS)

Hu, A.M.; Li, M.; Dali, D.L. Mao; Liang, K.M.

2005-01-01

Spodumene-willemite glass ceramics were produced by replacement of Al 2 O 3 in lithium aluminium silicate by ZnO. With replacement of Al 2 O 3 by ZnO, the batch melting temperature, glass transition temperature (T g ) and crystallization temperature (T p ) all decreased. The main crystalline phases precipitated were eucriptite, β-spodumene and willemite (Zn 2 SiO 4 ). All compositions of glass ceramics showed bulk crystallization. As ZnO content increased, the grain sizes and thermal expansion coefficients increased, while the flexural strength and fracture toughness of the glass-ceramics increased first, and then decreased. The mechanical properties were correlated with crystallization and morphology of glass ceramics

Vacancy behavior in a compressed fcc Lennard-Jones crystal

International Nuclear Information System (INIS)

Beeler, J.R. Jr.

1981-12-01

This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the stable vacancy configuration whenever cubic symmetry was present. This includes all of the isotropic compression cases and the particular uniaxial compression case (eta = √2) that give a bcc structure. In addition, the SCV was the stable configuration for uniaxial compression eta 1.20, the SV-OP is an extended defect and, therefore, a saddle point for SV-OP migration could not be determined. The mechanism for the transformation from the SCV to the SV-OP as the stable form at eta = 1.29 appears to be an alternating sign [101] and/or [011] shear process

Electronic structures and abnormal phonon behaviors of cobalt-modified Na0.5Bi0.5TiO3-6%BaTiO3 single crystals

Science.gov (United States)

Huang, T.; Zhang, P.; Xu, L. P.; Chen, C.; Zhang, J. Z.; Hu, Z. G.; Luo, H. S.; Chu, J. H.

2016-10-01

Optical properties, electronic structures, and structural variations of x wt% cobalt (Co) doped Na0.5Bi0.5TiO3-6%BaTiO3 (x=0%, 0.5%, 0.8%) single crystals have been studied by temperature-dependent optical ellipsometry and Raman spectra from 250 to 650 K. Based on the temperature evolution of electronic transitions (Ecp1 and Ecp2) and the phonon modes involving Ti-O vibrations, two critical temperature points exhibit an increasing trend with Co dopants, which are related to structural variations for ferroelectric to anti-ferroelectric, and anti-ferroelectric to paraelectric transition, respectively. Additionally, distinguishing abnormal phonon behaviors can be observed from Raman spectra for the crystal of x=0.5% and 0.8%, which show reverse frequency shift of the modes involving Ti-O vibration. It can be ascribed to different relative concentration of Co2+ and Co3+ in the crystals, which has been confirmed by X-ray Photoelectron Spectroscopy data.

Electronic structures and abnormal phonon behaviors of cobalt-modified Na0.5Bi0.5TiO3-6%BaTiO3 single crystals

Directory of Open Access Journals (Sweden)

T. Huang

2016-10-01

Full Text Available Optical properties, electronic structures, and structural variations of x wt% cobalt (Co doped Na0.5Bi0.5TiO3-6%BaTiO3 (x=0%, 0.5%, 0.8% single crystals have been studied by temperature-dependent optical ellipsometry and Raman spectra from 250 to 650 K. Based on the temperature evolution of electronic transitions (Ecp1 and Ecp2 and the phonon modes involving Ti-O vibrations, two critical temperature points exhibit an increasing trend with Co dopants, which are related to structural variations for ferroelectric to anti-ferroelectric, and anti-ferroelectric to paraelectric transition, respectively. Additionally, distinguishing abnormal phonon behaviors can be observed from Raman spectra for the crystal of x=0.5% and 0.8%, which show reverse frequency shift of the modes involving Ti-O vibration. It can be ascribed to different relative concentration of Co2+ and Co3+ in the crystals, which has been confirmed by X-ray Photoelectron Spectroscopy data.

Unsolved problems of crystallization and melting of flexible macromolecules

International Nuclear Information System (INIS)

Wunderlich, B.

1992-01-01

The thermodynamics, kinetics, and computer simulations of crystallization and melting is discussed. The thermodynamics is shown to be well understood, although for many specific crystals not enough details for full description are available. Experiments on the crystallization kinetics of poly(ethylene) and poly(oxyethylene) in the presence of crystal nuclei as a function of molecular mass revealed that with increasing mass, the crystallization behavior deviates increasingly from that of small, rigid molecules. Instead of showing a continuously changing, linear crystallization rate with temperature through the equilibrium melting temperature, T m 0 , these flexible macromolecules show a region of practically zero crystallization rate between T m 0 and about (T m 0 - 15) K, creating a temperature region of metastability in the melt that cannot be broken by nucleation with pregrown crystals. Molecular Nucleation was proposed as a cooperative process to be of overriding importance for the description of polymer crystallization, and to be at the center of segregation of molecules of lower molecular mass by growing crystal fronts. Initial efforts to model sufficiently large crystals using Monte Carlo and molecular dynamics methods are presented. Some of the short-time intermediates in the melting, crystallization, and annealing processes seem to have little similarity to commonly assumed models of crystallization and melting and are presented as discussion topics

Heavy Sexual Content Versus Safer Sex Content: A Content Analysis of the Entertainment Education Drama Shuga.

Science.gov (United States)

Booker, Nancy Achieng'; Miller, Ann Neville; Ngure, Peter

2016-12-01

Extremely popular with Kenyan youth, the entertainment-education drama Shuga was designed with specific goals of promoting condom use, single versus multiple sexual partners, and destigmatization of HIV. Almost as soon as it aired, however, it generated controversy due to its extensive sexual themes and relatively explicit portrayal of sexual issues. To determine how safer sex, antistigma messages, and overall sexual content were integrated into Shuga, we conducted a content analysis. Results indicated that condom use and HIV destigmatization messages were frequently and clearly communicated. Negative consequences for risky sexual behavior were communicated over the course of the entire series. Messages about multiple concurrent partnerships were not evident. In addition, in terms of scenes per hour of programming, Shuga had 10.3 times the amount of sexual content overall, 8.2 times the amount of sexual talk, 17.8 times the amount of sexual behavior, and 9.4 times the amount of sexual intercourse as found in previous analysis of U.S. entertainment programming. Research is needed to determine how these factors may interact to influence adolescent viewers of entertainment education dramas.

Anomalous doping of a molecular crystal monitored with confocal fluorescence microscopy: Terrylene in a p-terphenyl crystal

Science.gov (United States)

Białkowska, Magda; Deperasińska, Irena; Makarewicz, Artur; Kozankiewicz, Bolesław

2017-09-01

Highly terrylene doped single crystals of p-terphenyl, obtained by co-sublimation of both components, showed bright spots in the confocal fluorescence images. Polarization of the fluorescence excitation spectra, blinking and bleaching, and saturation behavior allowed us to attribute them to single molecules of terrylene anomalously embedded between two neighbor layers of the host crystal, in the (a,b) plane. Such an orientation of terrylene molecules results in much more efficient absorption and collection of the fluorescence photons than in the case of previously investigated molecules embedded in the substitution sites. The above conclusion was supported by quantum chemistry calculations. We postulate that the kind of doping considered in this work should be possible in other molecular crystals where the host molecules are organized in a herringbone pattern.

Ice crystal growth under the presence of krypton and methane at low temperature

Science.gov (United States)

Kawauchi, Taizo; Yoda, Yoshitaka; Fukutani, Katsuyuki

2018-02-01

To investigate the influence of foreign gas inclusion on the crystallization of ice, we studied the low-temperature (74 0.2) of Kr and CH4 enhance the formation of ice Ih and increase the crystal size, while at high foreign gas contents (R ⩽ 0.2) that may develop Kr or CH4 crystals below 92 K, the crystal size and relative amount of ice decrease strongly. The maximum ice Ih crystal size in the order of 200 nm was observed with either Kr or CH4 at 92 K for R = 0.2. We propose that Kr and CH4 induce the crystallization of ice by acting as a surfactant.

Crystallization features of normal alkanes in confined geometry.

Science.gov (United States)

Su, Yunlan; Liu, Guoming; Xie, Baoquan; Fu, Dongsheng; Wang, Dujin

2014-01-21

How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, and polymer blends, have complex molecular structures. Due to the multiple hierarchical structures and different size domains in polymer systems, confined hard environments for polymer crystallization exist widely in these materials. The confined geometry is closely related to both the phase metastability and lifetime of polymer. This affects the phase miscibility, microphase separation, and crystallization behaviors and determines both the performance of polymer materials and how easily these materials can be processed. Furthermore, the size effect of metastable states needs to be clarified in polymers. However, scientists find it difficult to propose a quantitative formula to describe the transition dynamics of metastable states in these complex systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, can provide a well-defined model system for studying the complex crystallization behaviors of polymer materials, surfactants, and lipids. Therefore, a deeper investigation of normal alkane phase behavior in confinement will help scientists to understand the crystalline phase transition and ultimate properties of many polymeric materials, especially polyolefins. In this Account, we provide an in-depth look at the research concerning the confined crystallization behavior of n-alkanes and binary mixtures in microcapsules by our laboratory and others. Since 2006, our group has developed a technique for synthesizing nearly monodispersed n-alkane containing microcapsules with controllable size and surface porous morphology. We applied an in situ polymerization method, using melamine-formaldehyde resin as shell material and nonionic surfactants as emulsifiers. The solid shell of microcapsules can provide a stable three-dimensional (3-D

Effect of titanium dioxide (TiO{sub 2}) on largely improving solar reflectance and cooling property of high density polyethylene (HDPE) by influencing its crystallization behavior

Energy Technology Data Exchange (ETDEWEB)

Wang, Shichao; Zhang, Jun, E-mail: zhangjun@njtech.edu.cn

2014-12-25

Highlights: • HDPE/TiO{sub 2} composites have more perfect crystal structure. • Refractive index is the key factor affecting the final solar reflectance. • HDPE/TiO{sub 2} composites can achieve high solar reflectance. • The real cooling property is in accordance with solar reflectance. - Abstract: In this study, the different crystal forms of titanium dioxide (TiO{sub 2}) were added into high density polyethylene (HDPE) to fabricate cool material. Crystal structure, crystallization behavior, crystal morphology were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscope (POM). Scanning electron microscope (SEM) was applied to observe dispersion of TiO{sub 2} particles in the HDPE matrix and the cross section morphology. The solar reflectance and actual cooling property were evaluated by UV–Vis–NIR spectrometer and a self-designed device. By adding TiO{sub 2} particles into HDPE matrix, the polymer chain could crystallize into more perfect and thermal stable lamella. The presence of TiO{sub 2} particles dramatically increased the number of nucleation site therefore decreased the crystal size. The subsequent solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of TiO{sub 2} particles in HDPE matrix. It was found the rutile TiO{sub 2} could largely improve the total solar reflectance from 28.2% to 51.1%. Finally, the temperature test showed that the composites had excellent cooling property, which was in accordance with solar reflectance result.

Microspheres with an ultra high holmium content for brachytherapy of malignancies

International Nuclear Information System (INIS)

Lira, Raphael A.; Myamoto, Douglas M.; Souza, Jaime R.; Nascimento, Nanci; Azevedo, Mariangela de Burgos M. de; Osso Junior, Joao A.; Martinelli, Jose R.

2011-01-01

The overall objective of this work is to develop biodegradable microspheres intended for internal radiation therapy which provides an improved treatment for hepatic carcinomas. The most studied brachytherapy system employing microspheres made of holmium-biopolymer system is composed by poly(L-lactic acid) (PLLA) and holmium acetylacetonate (HoAcAc). The importance of the holmium high content in the microspheres can be interpreted as follow from a therapeutic standpoint, to achieve an effective use of microspheres loaded with HoAcAc, a high content of holmium is required to yield enough radioactivity with a relatively low amount of microspheres.The usual amounts of holmium that are incorporated in the microspheres composed by poly(L-lactic acid) and HoAcAc are 17.0 ± 0.5% (w/w) of holmium, which corresponds to a loading of about 50% of HoAcAc. Different approaches have been investigated to increase that value. One updated approach towards this direction is the production of microspheres with ultrahigh holmium as matrix using HoAcAc crystals as the sole starting material without the use of biopolymer. Likewise, in the search of microspheres with increased holmium content , it has been demonstrated that by changing the HoAcAc crystal structure by its recrystallization from crystal phase to the amorphous there is lost of acetylacetonate and water molecules causing the increasing of the holmium content. Microspheres were prepared by solvent evaporation, using holmium acetylacetonate (HoAcAc) crystals as the sole ingredient. Microspheres were characterized by using light and scanning electron microscopy, infrared and Raman spectroscopy, differential scanning calorimetry, X-rays diffraction, and confocal laser scanning microscopy. (author)

Microspheres with an ultra high holmium content for brachytherapy of malignancies

Energy Technology Data Exchange (ETDEWEB)

Lira, Raphael A.; Myamoto, Douglas M.; Souza, Jaime R.; Nascimento, Nanci; Azevedo, Mariangela de Burgos M. de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Biotecnologia; Osso Junior, Joao A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Radiofarmacia; Martinelli, Jose R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencias e Tecnologia de Materiais

2011-07-01

The overall objective of this work is to develop biodegradable microspheres intended for internal radiation therapy which provides an improved treatment for hepatic carcinomas. The most studied brachytherapy system employing microspheres made of holmium-biopolymer system is composed by poly(L-lactic acid) (PLLA) and holmium acetylacetonate (HoAcAc). The importance of the holmium high content in the microspheres can be interpreted as follow from a therapeutic standpoint, to achieve an effective use of microspheres loaded with HoAcAc, a high content of holmium is required to yield enough radioactivity with a relatively low amount of microspheres.The usual amounts of holmium that are incorporated in the microspheres composed by poly(L-lactic acid) and HoAcAc are 17.0 {+-} 0.5% (w/w) of holmium, which corresponds to a loading of about 50% of HoAcAc. Different approaches have been investigated to increase that value. One updated approach towards this direction is the production of microspheres with ultrahigh holmium as matrix using HoAcAc crystals as the sole starting material without the use of biopolymer. Likewise, in the search of microspheres with increased holmium content , it has been demonstrated that by changing the HoAcAc crystal structure by its recrystallization from crystal phase to the amorphous there is lost of acetylacetonate and water molecules causing the increasing of the holmium content. Microspheres were prepared by solvent evaporation, using holmium acetylacetonate (HoAcAc) crystals as the sole ingredient. Microspheres were characterized by using light and scanning electron microscopy, infrared and Raman spectroscopy, differential scanning calorimetry, X-rays diffraction, and confocal laser scanning microscopy. (author)

Growth and characterization of high-purity SiC single crystals

Science.gov (United States)

Augustine, G.; Balakrishna, V.; Brandt, C. D.

2000-04-01

High-purity SiC single crystals with diameter up to 50 mm have been grown by the physical vapor transport method. Finite element analysis was used for thermal modeling of the crystal growth cavity in order to reduce stress in the grown crystal. Crystals are grown in high-purity growth ambient using purified graphite furniture and high-purity SiC sublimation sources. Undoped crystals up to 50 mm in diameter with micropipe density less than 100 cm -2 have been grown using this method. These undoped crystals exhibit resistivities in the 10 3 Ω cm range and are p-type due to the presence of residual acceptor impurities, mainly boron. Semi-insulating SiC material is obtained by doping the crystal with vanadium. Vanadium has a deep donor level located near the middle of the band gap, which compensates the residual acceptor resulting in semi-insulating behavior.

Properties of laser-crystallized polycrystalline SiGe thin films

Energy Technology Data Exchange (ETDEWEB)

Weizman, Moshe

2008-06-06

In this thesis, structural, electrical, and optical properties of laser-crystallized polycrystalline Si{sub 1-x}Ge{sub x} thin films with 0crystallization of amorphous Si{sub 1-x}Ge{sub x} thin films with 0.3crystallized poly-Si{sub 1-x}Ge{sub x} thin films with 0crystallization method and Ge content. The defect density for solid-phase crystallized SiGe films was lower and amounted to N{sub s}=7 x 10{sup 17} cm{sup -3}. - Germanium-rich laser-crystallized poly-SiGe thin films exhibited mostly a broad atypical electric dipole spin resonance (EDSR) signal that was accompanied by a nearly temperature-independent electrical conductivity in the range 20-100 K. - Most likely, the origin of the grain boundary conductance is due to dangling-bond defects and not impurities. Metallic-like conductance occurs when the dangling-bond defect density is above a critical value of about N{sub C} {approx} 10{sup 18} cm{sup -3}. - Laser crystallized poly-Si{sub 1-x}Ge{sub x} thin films with x{>=}0.5 exhibit optical absorption behavior that is characteristic for disordered SiGe, implying that the absorption occurs primarily at the grain boundaries. A sub-band-gap absorption peak was found for

High-pressure behavior of intermediate scapolite: compressibility, structure deformation and phase transition

Science.gov (United States)

Lotti, Paolo; Comboni, Davide; Merlini, Marco; Hanfland, Michael

2018-05-01

Scapolites are common volatile-bearing minerals in metamorphic rocks. In this study, the high-pressure behavior of an intermediate member of the scapolite solid solution series (Me47), chemical formula (Na1.86Ca1.86K0.23Fe0.01)(Al4.36Si7.64)O24[Cl0.48(CO3)0.48(SO4)0.01], has been investigated up to 17.79 GPa, by means of in situ single-crystal synchrotron X-ray diffraction. The isothermal elastic behavior of the studied scapolite has been described by a III-order Birch-Murnaghan equation of state, which provided the following refined parameters: V 0 = 1110.6(7) Å3, {K_{{V_0}}} = 70(2) GPa ({β _{{V_0}}} = 0.0143(4) GPa-1) and {K_{{V}}^' = 4.8(7). The refined bulk modulus is intermediate between those previously reported for Me17 and Me68 scapolite samples, confirming that the bulk compressibility among the solid solution increases with the Na content. A discussion on the P-induced structure deformation mechanisms of tetragonal scapolite at the atomic scale is provided, along with the implications of the reported results for the modeling of scapolite stability. In addition, a single-crystal to single-crystal phase transition, which is displacive in character, has been observed toward a triclinic polymorph at 9.87 GPa. The high-pressure triclinic polymorph was found to be stable up to the highest pressure investigated.

Non-isothermal cold crystallization kinetics of poly(3-hydoxybutyrate) filled with zinc oxide

Energy Technology Data Exchange (ETDEWEB)

Ries, Andreas, E-mail: ries750@yahoo.com.br [Electrical Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil); Canedo, Eduardo L. [Materials Engineering Department, Federal University of Campina Grande, Campina Grande, PB 58429-900 (Brazil); Souto, Cícero R. [Electrical Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil); Wellen, Renate M.R. [Materials Engineering Department, Federal University of Paraíba, João Pessoa, PB 58051-900 (Brazil)

2016-08-10

Highlights: • Non-isothermal cold crystallization kinetics of PHB filled with ZnO is presented. • Pseudo-Avrami model is best for describing an individual crystallization condition. • Mo model is allows to judge the kinetics of a condition untested in this work. • ZnO affects the kinetics irregularly. - Abstract: The non-isothermal cold crystallization kinetics of poly(3-hydroxybutyrate) (PHB) and PHB-ZnO composites, with ZnO content of 1%, 5% and 10% per weight, was investigated at different heating rates (5, 7.5, 10, 15, 20 and 30 °C/min) using differential scanning calorimetry. Both, Kissinger and Friedman activation energies predict correctly the slowest and fastest crystallizing composition. It was further found, that ZnO can neither be classified as a crystallization accelerator, nor as a crystallization inhibitor; its action is strongly concentration dependent. The empirical Pseudo-Avrami model has the best overall capability for fitting the experimental kinetic data. However, since the Pseudo-Avrami exponent was found to vary irregularly with heating rate and filler content, this model should not be applied for kinetic predictions of an arbitrary composition or an untested heating rate. In such cases, Mo's model should be used.

Ultra-fast solid state electro-optical modulator based on liquid crystal polymer and liquid crystal composites

Energy Technology Data Exchange (ETDEWEB)

Ouskova, Elena; Sio, Luciano De, E-mail: luciano@beamco.com; Vergara, Rafael; Tabiryan, Nelson [Beam Engineering for Advanced Measurements Company, Winter Park, Florida 32789 (United States); White, Timothy J.; Bunning, Timothy J. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7707 (United States)

2014-12-08

A different generation of polymer-dispersed liquid crystals (PDLCs) based on a liquid crystalline polymer host is reported wherein the fluid behavior of the reactive mesogenic monomer is an enabler to concentration windows (liquid crystal polymer/liquid crystal) (and subsequent morphologies) not previously explored. These liquid crystal (LC) polymer/LC composites, LCPDLCs, exhibit excellent optical and electro-optical properties with negligible scattering losses in both the ON and OFF states. These systems thus have application in systems where fast phase modulation of optical signal instead of amplitude control is needed. Polarized optical microscopy and high resolution scanning electron microscopy confirm a bicontinuous morphology composed of aligned LC polymer coexisting with a phase separated LC fluid. Operating voltages, switching times, and spectra of LCPDLCs compare favourably to conventional PDLC films. The LCPDLCs exhibit a low switching voltage (4–5 V/μm), symmetric and submillisecond (200 μs) on/off response times, and high transmission in both the as formed and switched state in a phase modulation geometry.

Effect of elastic anisotropy of crystal grain on stress intensity factor

Energy Technology Data Exchange (ETDEWEB)

Kamaya, Masayuki [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan)

2002-09-01

The stress intensity factor (SIF) is used widely for evaluating integrity of cracked components. Usually, the SIF obtained under isotropic elastic conditions is used for the evaluations. Although, macroscopic elastic behaviors of polycrystal materials can be considered isotropic, each crystal has anisotropic elastic properties. This implies that if the crack size is small and the influence of anisotropic elastic properties on the stress around cracks is significant, the SIF evaluated under anisotropic elastic conditions may differ from the SIF obtained under isotropic elastic conditions. In the present study, the effect of anisotropic elasticity on the SIF was evaluated by using the finite element analysis (FEA). First, the SIF of semi-circular cracks located in a single crystal was evaluated. It was found that the SIF is affected crystal orientation. Secondly, FEA using a polycrystal model was performed. It was found that the change in the SIF was caused by crack tip crystal orientation as well as the deformation constraint from neighboring crystals. Finally, the statistical tendency of change in the SIF caused by the anisotropic elastic properties and the relationship with crack size were examined. The influence of the local SIF on crack growth behavior is also discussed. (author)

Effect of elastic anisotropy of crystal grain on stress intensity factor

International Nuclear Information System (INIS)

Kamaya, Masayuki

2002-01-01

The stress intensity factor (SIF) is used widely for evaluating integrity of cracked components. Usually, the SIF obtained under isotropic elastic conditions is used for the evaluations. Although, macroscopic elastic behaviors of polycrystal materials can be considered isotropic, each crystal has anisotropic elastic properties. This implies that if the crack size is small and the influence of anisotropic elastic properties on the stress around cracks is significant, the SIF evaluated under anisotropic elastic conditions may differ from the SIF obtained under isotropic elastic conditions. In the present study, the effect of anisotropic elasticity on the SIF was evaluated by using the finite element analysis (FEA). First, the SIF of semi-circular cracks located in a single crystal was evaluated. It was found that the SIF is affected crystal orientation. Secondly, FEA using a polycrystal model was performed. It was found that the change in the SIF was caused by crack tip crystal orientation as well as the deformation constraint from neighboring crystals. Finally, the statistical tendency of change in the SIF caused by the anisotropic elastic properties and the relationship with crack size were examined. The influence of the local SIF on crack growth behavior is also discussed. (author)

Crystallization mechanisms of acicular crystals

Science.gov (United States)

Puel, François; Verdurand, Elodie; Taulelle, Pascal; Bebon, Christine; Colson, Didier; Klein, Jean-Paul; Veesler, Stéphane

2008-01-01

In this contribution, we present an experimental investigation of the growth of four different organic molecules produced at industrial scale with a view to understand the crystallization mechanism of acicular or needle-like crystals. For all organic crystals studied in this article, layer-by-layer growth of the lateral faces is very slow and clear, as soon as the supersaturation is high enough, there is competition between growth and surface-activated secondary nucleation. This gives rise to pseudo-twinned crystals composed of several needle individuals aligned along a crystallographic axis; this is explained by regular over- and inter-growths as in the case of twinning. And when supersaturation is even higher, nucleation is fast and random. In an industrial continuous crystallization, the rapid growth of needle-like crystals is to be avoided as it leads to fragile crystals or needles, which can be partly broken or totally detached from the parent crystals especially along structural anisotropic axis corresponding to weaker chemical bonds, thus leading to slower growing faces. When an activated mechanism is involved such as a secondary surface nucleation, it is no longer possible to obtain a steady state. Therefore, the crystal number, size and habit vary significantly with time, leading to troubles in the downstream processing operations and to modifications of the final solid-specific properties. These results provide valuable information on the unique crystallization mechanisms of acicular crystals, and show that it is important to know these threshold and critical values when running a crystallizer in order to obtain easy-to-handle crystals.

Students’ Digital Photography Behaviors during a Multiday Environmental Science Field Trip and Their Recollections of Photographed Science Content

Directory of Open Access Journals (Sweden)

Victor R. Lee

2014-01-01

Full Text Available Taking photographs to document the experiences of an educational field trip is becoming a common activity for teachers and students alike. Considering the regular creation of photographic artifacts, our goal in this paper is to explore students’ picture taking behavior and their recollections of science content associated with their photographs. In this study, we partnered with a class of fifth-grade students in the United States and provided each student with a digital camera to document their experiences during an environmental science field trip at a national park. We report the frequency of photography behaviors according to which activities were most often documented by the students and specifically that students tended to document more of their experiences when they were in outdoor, natural spaces rather than inside of visitor centers or museums. Also, through an analysis of students’ comments about the science content captured in their photographs we observe that students’ comments about photographs of the outdoors tended to show greater depth and complexity than those that were taken in indoor, museum-like spaces.

Study of the effect of the silver content on the structural and mechanical behavior of Ag–ZrCN coatings for orthopedic prostheses

Energy Technology Data Exchange (ETDEWEB)

Ferreri, I., E-mail: isabelferreri@gmail.com [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); CEB, Centre for Biological Engineering, University of Minho, Campus of Gualtar, 4700-057 (Portugal); Lopes, V. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Calderon V, S. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Tavares, C.J. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Carvalho, S. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal)

2014-09-01

With the increase of elderly population and health problems that are arising nowadays, hip joint prostheses are being widely used. However, it is estimated that 20% of hip replacement surgeries simply fails after few years, mainly due to wear fatigue. Bearing this in mind, this work reports on the development of new coatings that are able to sustain long and innocuous life inside the patient, which will confer to the usual biomaterials improved physical, mechanical and tribological properties. In particular, the development of multifunctional coatings based on Ag-ZrCN, prepared by DC reactive magnetron sputtering using two targets, Zr and a modified Zr target, in an Ar + C{sub 2}H{sub 2} + N{sub 2} atmosphere. Silver pellets were placed in the erosion area of the alloyed Zr target in order to obtain a silver content up to 8 at.%. The structural results obtained by x-ray diffraction show that the coatings crystallize in a NaCl crystal structure typical of ZrC{sub 1-x}N{sub x}. The increase of Ag content promoted the formation of an additional a-CN{sub x} amorphous phase, besides a silver crystalline phase. Hardness is decreasing, as increasing silver content. Despite the low thicknesses, adhesion values (L{sub C3}) can be considered as good. Dynamic fatigue results suggest that these coatings system can be a real asset in terms of mechanical properties, by improving the performance of usual Stainless Steel 316 L biomaterials. - Highlights: • ZrCN, silver and carbon based amorphous phases, form the structure of the coatings. • Ag–ZrCN coatings have a high capacity to withstand an impact load without fracturing. • Silver incorporation reduces the fatigue failures of the coatings. • The films possess mechanical resistance and biocompatibility, required in prostheses.

Crystal structure determination and thermal behavior upon melting of p-synephrine

Energy Technology Data Exchange (ETDEWEB)

Rosa, Frédéric [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France); Négrier, Philippe [Laboratoire Ondes et Matière d' Aquitaine, Université de Bordeaux, UMR CNRS 5798, 351 cours de la Libération, 33 405 Talence Cedex (France); Corvis, Yohann [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France); Espeau, Philippe, E-mail: philippe.espeau@parisdescartes.fr [Unité de Technologies Chimiques et Biologiques pour la Santé, U1022 INSERM, UMR8258 CNRS, Faculté des Sciences Pharmaceutiques et Biologiques, Université Paris Descartes, Sorbonne Paris Cité, 4 Avenue de l' Observatoire, 75006 Paris (France)

2016-05-20

Highlights: • The refinement of the crystal structure is achieved from X-ray powder diffraction. • P-Synephrine is revealed to be a racemic compound. • Degradation during melting can be bypassed using high DSC scan rates. • The temperature and enthalpy of melting are then proposed for this compound. - Abstract: The crystal structure of p-synephrine was solved from a high-resolution X-ray powder diffraction pattern optimized by energy-minimization calculations using the Dreiding force field. The title compound crystallizes in a monoclinic system (space group P2{sub 1}/c, Z = 4, with a = 8.8504(11) Å, b = 12.1166(15) Å, c = 9.7820(11) Å, β = 122.551(2)°, V = 884.21(19) Å{sup 3} and d = 1.256 g cm{sup −3}). Since p-synephrine degrades upon melting, its melting data were determined from DSC experiments carried out as a function of the heating rate. This method allowed determining a melting temperature and enthalpy equal to 199.8 ± 1.3 °C and 57 ± 3 kJ mol{sup −1}, respectively.

Crystal structure and thermal behavior of KB3O6

International Nuclear Information System (INIS)

Bubnova, R.S.; Fundamenskij, V.S.; Filatov, S.K.; Polyakova, I.G.

2004-01-01

The structure of potassium triborate prepared in metastable state by crystallization from melt at ∼ 800 deg C was studied by the method of X-ray diffraction analysis. It was ascertained that KB 3 O 6 belongs to monoclinic crystal system, space group P2 1 /c, a = 9.319(1), b = 6.648(1), c = 21.094(2) A, β = 94.38(1) deg, Z = 12. The compound is referred to a new structural type. Anion of the structure is a single boron-oxygen frame formed by three independent rigid triborate rings of [B 3 O 5 ] - , each of them consisting of two BO 3 triangles and BO 4 tetrahedron. Phase transformations during KB 3 O 6 heating up to 800 deg C, as well as thermal expansion in the range of 20-650 deg C, were studied [ru

Photonics of liquid-crystal structures: A review

Energy Technology Data Exchange (ETDEWEB)

Palto, S. P., E-mail: palto@online.ru; Blinov, L M; Barnik, M I; Lazarev, V V; Umanskii, B A; Shtykov, N M [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2011-07-15

The original results of studies of the electro-optical and laser effects which have been performed at the Laboratory of Liquid Crystals of the Institute of Crystallography, Russian Academy of Sciences, over the last few years are reviewed. Cholesteric liquid crystals as vivid representatives of photonic structures and their behavior in an electric field are considered in detail. The formation of higher harmonics in the periodic distribution of the director field in a helical liquid crystal structure and, correspondingly, the new (anharmonic) mode of electro-optical effects are discussed. Another group of studies is devoted to bistable light switching by an electric field in chiral nematics. Polarization diffraction gratings controlled by an electric field are also considered. The results of studies devoted to microlasers on various photonic structures with cholesteric and nematic liquid crystals are considered in detail. Particular attention is given to the new regime: leaky-mode lasing. Designs of liquid crystal light amplifiers and their polarization, field, and spectral characteristics are considered in the last section.

Crystallization and preliminary crystallographic analysis of human glycosylated haemoglobin

International Nuclear Information System (INIS)

Syakhovich, Vitaly E.; Saraswathi, N. T.; Ruff, Marc; Bokut, Sergey B.; Moras, Dino

2006-01-01

Non enzymatic modification of haemoglobin by glucose plays an important role in diabetes pathogenesis. Here the purification, characterization and crystallization of human glycosylated haemoglobin are reported. Human glycosylated haemoglobin A 1C is a stable minor variant formed in vivo by post-translational modification of the main form of haemoglobin by glucose. Crystals of oxyHbA 1C were obtained using the hanging-drop vapour-diffusion method and PEG as precipitant. The diffraction pattern of the crystal extends to a resolution of 2.3 Å at 120 K. The crystals belong to space group C2, with unit-cell parameters a = 237.98, b = 59.27, c = 137.02 Å, α = 90.00, β = 125.40, γ = 90.00°. The presence of two and a half molecules per asymmetric unit gives a crystal volume per protein weight (V M ) of 9.70 Å 3 Da −1 and a solvent content of 49%

Crystallization and preliminary crystallographic analysis of human glycosylated haemoglobin

Energy Technology Data Exchange (ETDEWEB)

Syakhovich, Vitaly E. [Department of Biochemistry and Biophysics, International Sakharov Environmental University, Dolgobrodskaya St 23, 220009 Minsk (Belarus); Saraswathi, N. T.; Ruff, Marc, E-mail: ruff@igbmc.u-strasbg.fr [Département de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, BP 10142, 67404 Illkirch (France); Bokut, Sergey B. [Department of Biochemistry and Biophysics, International Sakharov Environmental University, Dolgobrodskaya St 23, 220009 Minsk (Belarus); Moras, Dino [Département de Biologie et Génomique Structurales, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 1 Rue Laurent Fries, BP 10142, 67404 Illkirch (France); Department of Biochemistry and Biophysics, International Sakharov Environmental University, Dolgobrodskaya St 23, 220009 Minsk (Belarus)

2006-02-01

Non enzymatic modification of haemoglobin by glucose plays an important role in diabetes pathogenesis. Here the purification, characterization and crystallization of human glycosylated haemoglobin are reported. Human glycosylated haemoglobin A{sub 1C} is a stable minor variant formed in vivo by post-translational modification of the main form of haemoglobin by glucose. Crystals of oxyHbA{sub 1C} were obtained using the hanging-drop vapour-diffusion method and PEG as precipitant. The diffraction pattern of the crystal extends to a resolution of 2.3 Å at 120 K. The crystals belong to space group C2, with unit-cell parameters a = 237.98, b = 59.27, c = 137.02 Å, α = 90.00, β = 125.40, γ = 90.00°. The presence of two and a half molecules per asymmetric unit gives a crystal volume per protein weight (V{sub M}) of 9.70 Å{sup 3} Da{sup −1} and a solvent content of 49%.

Dislocation motion in InSb crystals under a magnetic field

CERN Document Server

Darinskaya, E V; Erofeeva, S A

2002-01-01

Dislocation displacements under the action of a permanent magnetic field without mechanical loading in differently doped InSb crystals are investigated. The dependences of the mean dislocation path length and the relative number of divergence and tightening half-loops on the magnetic induction and preliminary load are obtained. Experiments on n-InSb crystals with Te impurities and on p-InSb crystals with Ge impurities have shown a sensitivity of the magnetoplasticity to the conductivity type and the dopant content. Study of the magnetoplastic effect in the initial deformed InSb crystals shows that internal stresses decrease the lengths of divergence dislocation paths and simultaneously increase the threshold magnetic field above which the magnetoplastic effect exists. Possible reasons for the observed phenomena are discussed.

The effects to the structure and electrochemical behavior of zinc phosphate conversion coatings with ethanolamine on magnesium alloy AZ91D

International Nuclear Information System (INIS)

Li Qing; Xu Shuqiang; Hu Junying; Zhang Shiyan; Zhong Xiankang; Yang Xiaokui

2010-01-01

This paper discussed a zinc phosphate conversion coating formed on magnesium alloy AZ91D from the phosphating bath with varying amounts of ethanolamine (MEA). The effects of MEA on the form, structure, phase composition and electrochemical behavior of the phosphate coatings were examined using an scanning electron microscopy (SEM), X-ray diffraction (XRD) potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Interpretations of the electrical elements of the equivalent circuit were obtained from the SEM structure of the coatings, assumed to be formed of two layers: an outer porous crystal layer and an inner flat amorphous layer. The result showed that adding MEA refined the microstructure of the crystal layer and that the phosphate coating, derived at the optimal content of 1.2 g/L, with the most uniform and compact outer crystal layer provided the best corrosion protection.

Two-dimensional plasma photonic crystals in dielectric barrier discharge

International Nuclear Information System (INIS)

Fan Weili; Dong Lifang; Zhang Xinchun

2010-01-01

A series of two-dimensional plasma photonic crystals have been obtained by filaments' self-organization in atmospheric dielectric barrier discharge with two water electrodes, which undergo the transition from square to square superlattice and finally to the hexagon. The spatio-temporal behaviors of the plasma photonic crystals in nanosecond scale have been studied by optical method, which show that the plasma photonic crystal is actually an integration of different transient sublattices. The photonic band diagrams of the transverse electric (TE) mode and transverse magnetic mode for each sublattice of these plasma photonic crystals have been investigated theoretically. A wide complete band gap is formed in the hexagonal plasma photonic crystal with the TE mode. The changes of the band edge frequencies and the band gap widths in the evolvement of different structures are studied. A kind of tunable plasma photonic crystal which can be controlled both in space and time is suggested.

The swelling behavior of montmorillonite as affected by the grain size by in situ X-ray diffraction experiments

International Nuclear Information System (INIS)

Morodome, S.; Kawamura, K.; Owada, H.; Yahagi, R.; Kobayashi, I.

2012-01-01

Document available in extended abstract form only. In many existing researches, the swelling behavior and impermeability of smectitic engineered barrier materials in disposal facilities of radioactive waste was investigated. In the RWMC-project, the effect of smectite content on the mechanical and hydraulic behavior of smectitic materials is investigated and modeled to introduce into THMC analysis. However, since smectite is a natural resource, physical and chemical properties are different with places of production. In order to model the swelling behavior and impermeability of smectitic materials, not only the smectite content but also layer charge and crystal size will be the primary factors. In addition, smectite types and impurity minerals contents or soluble salts affect bentonite characteristic, as well. In this research, in order to focus on the effect of grain size of smectite, the swelling behavior of smectitic materials which are the same place of production but are different grain size were investigated. The smectitic material used in this study was Kunipia-F (Kunimine Industry Co. Ltd., Japan), which is from the Tukinuno Mine, Yamagata prefecture, Japan, and is purified montmorillonite produced by hydraulic elutriation. It is considered that the montmorillonite, Kunipia-F, has large crystal size, and for example Kunipia-F is able to make a sheet when drying weak solution. The grain size was conditioned by jet mill pulverizer. The pulverizing was conducted by making each other collide with high speed. The grain size of the intact and pulverized samples was measured by using of the laser scattering particle distribution analyzer and SEM. The swelling behavior was measured by in situ X-ray diffraction using of a sample chamber which can control the temperature and humidity precisely. The result of the laser scattering analysis denoted that the pulverized sample fined down expressly. The difference of the crystal aspect ratio of the pre- and post

Thermal, mechanical, optical and dielectric properties of piperazinium hydrogen phosphite monohydrate NLO single crystal

Science.gov (United States)

Rajkumar, R.; Praveen Kumar, P.

2018-05-01

Optical transparent crystal of piperazinium hydrogen phosphite monohydrate (PHPM) was grown by slow evaporation method. The grown crystal was characterized by single crystal X-ray diffraction analysis and the crystal belongs to monoclinic system. The functional groups present in PHPM crystal were confirmed by FTIR analysis. UV-Visible spectrum shows that the PHPM crystal is transparent in the visible region. The mechanical behavior of PHPM crystal was characterized by Vickers hardness test. Thermal stability of PHPM crystal was analyzed by thermogravimetric analysis. Dielectric studies were also carried out for the grown crystal. The third-order nonlinear parameters such as nonlinear refractive index and nonlinear absorption coefficient have been calculated using Z scan technique.

Anisotropy of Single-Crystal Silicon in Nanometric Cutting.

Science.gov (United States)

Wang, Zhiguo; Chen, Jiaxuan; Wang, Guilian; Bai, Qingshun; Liang, Yingchun

2017-12-01

The anisotropy exhibited by single-crystal silicon in nanometric cutting is very significant. In order to profoundly understand the effect of crystal anisotropy on cutting behaviors, a large-scale molecular dynamics model was conducted to simulate the nanometric cutting of single-crystal silicon in the (100)[0-10], (100)[0-1-1], (110)[-110], (110)[00-1], (111)[-101], and (111)[-12-1] crystal directions in this study. The simulation results show the variations of different degrees in chip, subsurface damage, cutting force, and friction coefficient with changes in crystal plane and crystal direction. Shear deformation is the formation mechanism of subsurface damage, and the direction and complexity it forms are the primary causes that result in the anisotropy of subsurface damage. Structurally, chips could be classified into completely amorphous ones and incompletely amorphous ones containing a few crystallites. The formation mechanism of the former is high-pressure phase transformation, while the latter is obtained under the combined action of high-pressure phase transformation and cleavage. Based on an analysis of the material removal mode, it can be found that compared with the other crystal direction on the same crystal plane, the (100)[0-10], (110)[-110], and (111)[-101] directions are more suitable for ductile cutting.

Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents

International Nuclear Information System (INIS)

Guo, M.X.; Zhang, Y.; Zhang, X.K.; Zhang, J.S.; Zhuang, L.Z.

2016-01-01

The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

Fractionation of the platinum-group elments and Re during crystallization of basalt in Kilauea Iki Lava Lake, Hawaii

Science.gov (United States)

Pitcher, L.; Helz, R.T.; Walker, R.J.; Piccoli, P.

2009-01-01

Kilauea Iki lava lake formed during the 1959 summit eruption of Kilauea Volcano, then crystallized and differentiated over a period of 35??years. It offers an opportunity to evaluate the fractionation behavior of trace elements in a uniquely well-documented basaltic system. A suite of 14 core samples recovered from 1967 to 1981 has been analyzed for 5 platinum-group elements (PGE: Ir, Os, Ru, Pt, Pd), plus Re. These samples have MgO ranging from 2.4 to 26.9??wt.%, with temperatures prior to quench ranging from 1140????C to ambient (110????C). Five eruption samples were also analyzed. Osmium and Ru concentrations vary by nearly four orders of magnitude (0.0006-1.40??ppb for Os and 0.0006-2.01??ppb for Ru) and are positively correlated with MgO content. These elements behaved compatibly during crystallization, mostly likely being concentrated in trace phases (alloy or sulfide) present in olivine phenocrysts or included chromite. Iridium also correlates positively with MgO, although less strongly than Os and Ru. The somewhat poorer correlation for Ir, compared with Os and Ru, may reflect variable loss of Ir as volatile IrF6 in some of the most magnesian samples. Rhenium is negatively correlated with MgO, behaving as an incompatible trace element. Its behavior in the lava lake is complicated by apparent volatile loss of Re, as suggested by a decrease in Re concentration with time of quenching for lake samples vs. eruption samples. Platinum and Pd concentrations are negatively, albeit weakly, correlated with MgO, so these elements were modestly incompatible during crystallization of the major silicate phases. Palladium contents peaked before precipitation of immiscible sulfide liquid, however, and decline sharply in the most differentiated samples. In contrast, Pt appears to have been unaffected by sulfide precipitation. Microprobe data confirm that Pd entered the sulfide liquid before Re, and that Pt is not strongly chalcophile in this system. Occasional high Pt values

Quality characteristics and thermal behavior of buriti (Mauritia flexuosa L.) oil

International Nuclear Information System (INIS)

Freitas, M.L.F.; Chisté, R.C.; Polachini, T.C.; Sardella, L.A.C.Z.; Aranha, C.P.M.; Ribeiro, A.P.B.; Nicoletti, V.R.

2017-01-01

This work reports a complete characterization of buriti oil. Physicochemical properties were determined according to AOCS methodologies and thermophysical properties were measured using a controlled stress rheometer and a digital electronic density meter. β-carotene and tocopherol contents were obtained using HPLC systems. Fatty acids and acylglycerol classes were determined using GC and HPSEC systems, respectively, while triacylglycerol composition was estimated using the software PrOleos. Thermal behavior (crystallization and melting) was analyzed using a DSC. The results attested high levels of total carotenoids with β-carotene as the major one; total tocopherols contained α- and β-tocopherols which accounted for 91% of the total; and monounsaturated fatty acids were mainly represented by oleic acid. The results showed close agreement between density and viscosity of buriti and olive oils. The crystallization and melting peaks occurred at -43.06 °C and -2.73 °C, respectively. These properties enable Buriti oil to be recommended as an excellent alternative for enriching foods with bioactive compounds. [es

Quality characteristics and thermal behavior of buriti (Mauritia flexuosa L. oil

Directory of Open Access Journals (Sweden)

M. L.F. Freitas

2018-01-01

Full Text Available This work reports a complete characterization of buriti oil. Physicochemical properties were determined according to AOCS methodologies and thermophysical properties were measured using a controlled stress rheometer and a digital electronic density meter. β-carotene and tocopherol contents were obtained using HPLC systems. Fatty acids and acylglycerol classes were determined using GC and HPSEC systems, respectively, while triacylglycerol composition was estimated using the software PrOleos. Thermal behavior (crystallization and melting was analyzed using a DSC. The results attested high levels of total carotenoids with β-carotene as the major one; total tocopherols contained α- and β-tocopherols which accounted for 91% of the total; and monounsaturated fatty acids were mainly represented by oleic acid. The results showed close agreement between density and viscosity of buriti and olive oils. The crystallization and melting peaks occurred at -43.06 °C and -2.73 °C, respectively. These properties enable Buriti oil to be recommended as an excellent alternative for enriching foods with bioactive compounds.

Single-crystal growth of ceria-based materials; Einkristallzuechtung von Materialien auf der Basis von Cerdioxid

Energy Technology Data Exchange (ETDEWEB)

Ulbrich, Gregor

2015-07-23

In this work it could be shown that Skull-Melting is a suitable method for growing ceria single crystals. Twenty different ceria-based single crystals could be manufactured. It was possible to dope ceria single crystals with Gd, Sm, Y, Zr, Ti, Ta, and Pr in different concentrations. Also co-doping with the named metals was realized. However, there remain some problems for growing ceria-based single crystals by Skull-Melting. As ignition metal zirconium was used because no ceria-based material works well. For that reason all single crystals show small zirconium contamination. Another problem is the formation of oxygen by the heat-induced reduction of ceria during the melting process. Because of that the skull of sintered material is often destroyed by gas pressure. This problem had to be solved individually for every single crystal. The obtained single crystals were characterized using different methods. To ensure the single crystal character the y were examined by Laue diffraction. All manufactured crystals are single crystals. Also powder diffraction patterns of the milled and oxidized samples were measured. For the determination of symmetry and metric the structural parameters were analyzed by the Rietveld method. All synthesized materials crystallize in space group Fm-3m known from calcium fluoride. The cubic lattice parameter a was determined for all crystals. In the case of series with different cerium and zirconium concentrations a linear correlation between cerium content and cubic lattice parameter was detected. The elemental composition was determined by WDX. All crystals show a homogeneous elemental distribution. The oxygen content was calculated because the WDX method isn't useful for determination.

Two-stage magnetic orientation of uric acid crystals as gout initiators

Science.gov (United States)

Takeuchi, Y.; Miyashita, Y.; Mizukawa, Y.; Iwasaka, M.

2014-01-01

The present study focuses on the magnetic behavior of uric acid crystals, which are responsible for gout. Under a sub-Tesla (T)-level magnetic field, rotational motion of the crystals, which were caused by diamagnetic torque, was observed. We used horizontal magnetic fields with a maximum magnitude of 500 mT generated by an electromagnet to observe the magnetic orientation of the uric acid microcrystals by a microscope. The uric acid crystals showed a perpendicular magnetic field orientation with a minimum threshold of 130 mT. We speculate that the distinct diamagnetic anisotropy in the uric acid crystals resulted in their rotational responses.

Morphology and solubility of multiple crystal forms of Taka-amylase A

Science.gov (United States)

Ninomiya, Kumiko; Yamamoto, Tenyu; Oheda, Tadashi; Sato, Kiyotaka; Sazaki, Gen; Matsuura, Yoshiki

2001-01-01

An α-amylase originating from a mold Aspergillus oryzae, Taka-amylase A (Mr of 52 kDa, pI of 3.8), has been purified to an electrophoretically single band grade. Crystallization behaviors were investigated using ammonium sulfate and polyethleneglycol 8000 as precipitants. The variations in the morphology of the crystals obtained with changing crystallization parameters are described. Five apparently different crystal forms were obtained, and their morphology and crystallographic data have been determined. Solubility values of four typical forms were measured using a Michelson-type two-beam interferometer. The results of these experiments showed that this protein can be a potentially interesting and useful model for crystal growth study with a gram-amount availability of pure protein sample.

Oriented Crystallization and Mechanical Properties of Polypropylene Nucleated on Fibrillated Polytetrafluorethylene Scaffolds

NARCIS (Netherlands)

van der Meer, D.W.; Milazzo, Daniel; Sanguineti, Aldo; Vancso, Gyula J.

2005-01-01

It is known that friction deposited polytetrafluoroethylene (PTFE) layers are able to nucleate crystallization of thin films of isotactic polypropylene (iPP). In order to investigate the influence of PTFE on the crystallization behavior and morphology of iPP in bulk, PTFE-particles of two different

Liquid Crystal Phases of Colloidal Platelets and their Use as Nanocomposite Templates

NARCIS (Netherlands)

Mourad, M.C.D.|info:eu-repo/dai/nl/304837563

2009-01-01

This thesis explores the gelation and liquid crystal phase behavior of colloidal dispersions of platelike particles as well as the use of such dispersions for the generation of nanocomposites. We report on the sol-gel, sol-glass and liquid crystal phase transitions of positively charged colloidal

Defect studies of ZnO single crystals electrochemically doped with hydrogen

Science.gov (United States)

Čížek, J.; Žaludová, N.; Vlach, M.; Daniš, S.; Kuriplach, J.; Procházka, I.; Brauer, G.; Anwand, W.; Grambole, D.; Skorupa, W.; Gemma, R.; Kirchheim, R.; Pundt, A.

2008-03-01

Various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. The hydrogen content in the crystals is determined by nuclear reaction analysis and it is found that already 0.3at.% H exists in chemically bound form in the virgin ZnO crystals. A single positron lifetime of 182ps is detected in the virgin crystals and attributed to saturated positron trapping at Zn vacancies surrounded by hydrogen atoms. It is demonstrated that a very high amount of hydrogen (up to ˜30at.%) can be introduced into the crystals by electrochemical doping. More than half of this amount is chemically bound, i.e., incorporated into the ZnO crystal lattice. This drastic increase of the hydrogen concentration is of marginal impact on the measured positron lifetime, whereas a contribution of positrons annihilated by electrons belonging to O-H bonds formed in the hydrogen doped crystal is found in coincidence Doppler broadening spectra. The formation of hexagonal shape pyramids on the surface of the hydrogen doped crystals by optical microscopy is observed and discussed.

Mesoscale martensitic transformation in single crystals of topological defects

Energy Technology Data Exchange (ETDEWEB)

Li, Xiao; Martínez-González, José A.; Hernández-Ortiz, Juan P.; Ramírez-Hernández, Abelardo; Zhou, Ye; Sadati, Monirosadat; Zhang, Rui; Nealey, Paul F.; de Pablo, Juan J.

2017-09-05

Liquid crystal blue phases (BPs) are highly ordered at two levels. Molecules exhibit orientational order at nanometer length scales, while chirality leads to ordered arrays of doubletwisted cylinders over micrometer scales. Past studies of polycrystalline BPs were challenged by grain boundaries between randomly oriented crystalline nanodomains. Here, the nucleation of BPs is controlled with considerable precision by relying on chemically nano-patterned surfaces, leading to macroscopic single-crystal BP specimens where the dynamics of meso-crystal formation can be directly observed. Theory and experiments show that transitions between two BPs having a different network structure proceed through local re-organization of the crystalline array, without diffusion of the double twisted cylinders. In solid crystals, martensitic transformations between crystal structures involve the concerted motion of a few atoms, without diffusion. The transformation between BPs, where crystal features arise in the sub-micron regime, is found to be martensitic in nature, with the diffusion-less feature associated to the collective behavior of the double twist cylinders. Single-crystal BPs are shown to offer fertile grounds for the study of directed crystal-nucleation and the controlled growth of soft matter.

Vitrification and Crystallization of Phase-Separated Metallic Liquid

Directory of Open Access Journals (Sweden)

Yun Cheng

2017-02-01

Full Text Available The liquid–liquid phase separation (LLPS behavior of Fe50Cu50 melt from 3500 K to 300 K with different rapid quenching is investigated by molecular dynamics (MD simulation based on the embedded atom method (EAM. The liquid undergoes metastable phase separation by spinodal decomposition in the undercooled regime and subsequently solidifies into three different Fe-rich microstructures: the interconnected-type structure is kept in the glass and crystal at a higher cooling rate, while the Fe-rich droplets are found to crystalize at a lower cooling rate. During the crystallization process, only Fe-rich clusters can act as the solid nuclei. The twinning planes can be observed in the crystal and only the homogeneous atomic stacking shows mirror symmetry along the twinning boundary. Our present work provides atomic-scale understanding of LLPS melt during the cooling process.

Alignment technology and applications of liquid crystal devices

CERN Document Server

Takatoh, Kohki; Hasegawa, Ray; Koden, Mitsushiro; Itoh, Nobuyuki; Hasegawa, Masaki

2005-01-01

Alignment phenomena are characteristic of liquid crystalline materials, and understanding them is critically important in understanding the essential features and behavior of liquid crystals and the performance of Liquid Crystal Devices (LCDs). Furthermore, in LCD production lines, the alignment process is of practical importance. Alignment Technologies and Applications of Liquid Crystal Devices demonstrates both the fundamental and practical aspects of alignment phenomena in liquid crystals. The physical basis of alignment phenomena is first introduced in order to aid the understanding of the various physical phenomena observed in the interface between liquid crystalline materials and alignment layer surfaces. Methods for the characterization of surfaces, which induce the alignment phenomena, and of the alignment layer itself are introduced. These methods are useful for the research of liquid crystalline materials and devices in academic research as well as in industry. In the practical sections, the alignme...

Sexy media matter: exposure to sexual content in music, movies, television, and magazines predicts black and white adolescents' sexual behavior.

Science.gov (United States)

Brown, Jane D; L'Engle, Kelly Ladin; Pardun, Carol J; Guo, Guang; Kenneavy, Kristin; Jackson, Christine

2006-04-01

To assess over time whether exposure to sexual content in 4 mass media (television, movies, music, and magazines) used by early adolescents predicts sexual behavior in middle adolescence. An in-home longitudinal survey of 1017 black and white adolescents from 14 middle schools in central North Carolina was conducted. Each teen was interviewed at baseline when he or she was 12 to 14 years old and again 2 years later using a computer-assisted self interview (audio computer-assisted self-interview) to ensure confidentiality. A new measure of each teen's sexual media diet (SMD) was constructed by weighting the frequency of use of 4 media by the frequency of sexual content in each television show, movie, music album, and magazine the teen used regularly. White adolescents in the top quintile of sexual media diet when 12 to 14 years old were 2.2 times more likely to have had sexual intercourse when 14 to 16 years old than those who were in the lowest SMD quintile, even after a number of other relevant factors, including baseline sexual behavior, were introduced. The relationship was not statistically significant for black adolescents after controlling for other factors that were more predictive, including parental disapproval of teen sex and perceived permissive peer sexual norms. Exposure to sexual content in music, movies, television, and magazines accelerates white adolescents' sexual activity and increases their risk of engaging in early sexual intercourse. Black teens appear more influenced by perceptions of their parents' expectations and their friends' sexual behavior than by what they see and hear in the media.

On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

Directory of Open Access Journals (Sweden)

J.-F. Gayet

2012-01-01

Full Text Available During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C. The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C and nadir looking remote sensing observations (DLR WALES Lidar. Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm⁻³, 30 km⁻¹ and 0.5 g m⁻³, respectively are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved

On the observation of unusual high concentration of small chain-like aggregate ice crystals and large ice water contents near the top of a deep convective cloud during the CIRCLE-2 experiment

Science.gov (United States)

Gayet, J.-F.; Mioche, G.; Bugliaro, L.; Protat, A.; Minikin, A.; Wirth, M.; Dörnbrack, A.; Shcherbakov, V.; Mayer, B.; Garnier, A.; Gourbeyre, C.

2012-01-01

During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/-58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique set of instruments for the extensive in situ cloud measurements of microphysical and optical properties (Polar Nephelometer, FSSP-300, Cloud Particle Imager and PMS 2-D-C) and nadir looking remote sensing observations (DLR WALES Lidar). Quasi-simultaneous space observations from MSG/SEVIRI, CALIPSO/CALIOP-WFC-IIR and CloudSat/CPR combined with airborne RASTA radar reflectivity from the French Falcon aircraft flying above the DLR Falcon depict very well convective cells which overshoot by up to 600 m the tropopause level. Unusual high values of the concentration of small ice particles, extinction, ice water content (up to 70 cm-3, 30 km-1 and 0.5 g m-3, respectively) are experienced. The mean effective diameter and the maximum particle size are 43 μm and about 300 μm, respectively. This very dense cloud causes a strong attenuation of the WALES and CALIOP lidar returns. The SEVIRI retrieved parameters confirm the occurrence of small ice crystals at the top of the convective cell. Smooth and featureless phase functions with asymmetry factors of 0.776 indicate fairly uniform optical properties. Due to small ice crystals the power-law relationship between ice water content (IWC) and radar reflectivity appears to be very different from those usually found in cirrus and anvil clouds. For a given equivalent reflectivity factor, IWCs are significantly larger for the overshooting cell than for the cirrus. Assuming the same prevalent microphysical properties over the depth of the overshooting cell, RASTA reflectivity profiles scaled into ice water content show that retrieved IWC up to 1 g m-3 may be observed near the cloud top

Sonocrystallization—Case Studies of Salicylamide Particle Size Reduction and Isoniazid Derivative Synthesis and Crystallization

Directory of Open Access Journals (Sweden)

Zhen-Yu Yang

2018-06-01

Full Text Available Two case studies of salicylamide particle size reduction and isoniazid derivative synthesis and crystallization realized using sonocrystallization were investigated. The size, habit, structure, thermal behavior, and spectrometric properties of sonocrystallized crystals were analyzed through scanning electron microscopy (SEM, powder X-ray diffractometry (PXRD, differential scanning calorimetry (DSC, and Fourier transform infrared (FTIR spectroscopy. The effects of the operating parameters, such as sonication intensity, sonication duration, and solution concentration, on sonocrystallization were compared. The crystal size of salicylamide was reduced from 595 μm (the original size and was efficiently manipulated to be between 40 and 80 μm. Moreover, compared with the crystal habits of unprocessed crystals and recrystallized crystals fabricated through conventional methods, the crystal habit of salicylamide could be modified to present a regular shape. The structure, thermal behavior, and spectrometric properties of sonocrystallized salicylamide were found to be in agreement with those of an unprocessed sample. For producing isoniazid derivative crystals, N′-(propan-2-ylidene-isonicotinohydrazide was synthesized using isoniazid in acetone at 318 K. The resulting solution was then cooled by applying power ultrasound to isolate N′-(propan-2-ylidene-isonicotinohydrazide crystals. The solid-state properties of the synthesized N′-(propan-2-ylidene-isonicotinohydrazide was verified through PXRD, DSC, and FTIR spectroscopy. The feasibility of particle size manipulation was then demonstrated through sonocrystallization.

Monoclinic mixed crystals of halogenomethanes CBr4-nCln (n = 0, ..., 4)

International Nuclear Information System (INIS)

Negrier, Philippe; Tamarit, Josep Ll.; Barrio, Maria; Pardo, Luis C.; Mondieig, Denise

2007-01-01

On the basis of the isostructural relationship between the low-temperature monoclinic (C2/c, Z = 32) phases of the halogenomethane CBr 4-n Cl n (n = 0, ..., 4), a set of mixed crystals has been analysed by means of high-resolution X-ray powder diffraction. It is shown that the monoclinic structure of pure and mixed crystals does not depend of the particularities of the dipolar (or dipole induced) interactions of the pure compound, neither on the composition of the mixed crystal, but on the relative content of the halogen atoms which controls the size of the molecule or the average molecule for the case of mixed crystals

Fundamental studies of the effect of crystal defects on CuInSe{sub 2}/CdS heterojunction behavior: Final report, 28 June 1993--30 June 1998

Energy Technology Data Exchange (ETDEWEB)

Rockett, A.

1999-11-17

This report describes the work performed by the University of Illinois at Urbana-Champaign. The following results were obtained under the work funded by this subcontract: (1) Point defects and electronic properties of Cu(In{sub 1-x}Ga{sub x})Se{sub 2}: New record results for hole mobilities in Cu(In{sub 1-x}Ga{sub x})Se{sub 2} based on single crystals grown by Rockett's group; Demonstrated the role of Ga in determining hole concentrations; Showed that Ga does not affect the hole mobility in this material and why this is the case; Determined the diffusion coefficient for Ga in single-crystal Cu(In{sub 1-x}Ga{sub x})Se{sub 2}; Demonstrated the structure and optoelectronic properties of the CuIn{sub 3}Se{sub 5} ordered-defect phase of CuInSe{sub 2}; Characterized the detailed effects of Na on Cu(In{sub 1-x}Ga{sub x})Se{sub 2} solar cells and on the fundamental properties of the material itself (reduces compensating donors in p-type materials); and In collaboration with groups at the Universities of Salford and Liverpool in the United Kingdom, studied the effect of ion implantation damage on Cu(In{sub 1-x}Ga{sub x})Se{sub 2} single-crystals. (2) Materials for and characterization of devices: Developed a novel contact metallurgy that improves adhesion to the underlying Mo back-contact in solar cells made with Cu(In{sub 1-x}Ga{sub x})Se{sub 2}; (This material has also yielded substantial novel materials science behaviors, including grain rotation and growth prior to phase separation in a metastable binary alloy.) Characterized the electroluminescence as a function of temperature and Ga content in Cu(In{sub 1-x}Ga{sub x})Se{sub 2} solar cells and showed that the radiative recombination pathways are not band-to-band as in normal semiconductors, but rather, proceed through defect states; and Working with a group at the University of Uppsala in Sweden, demonstrated novel aspects of the bonding and chemistry of dip-coated CdS heterojunction materials used as

Thermoelectricity in liquid crystals

Science.gov (United States)

Mohd Said, Suhana; Nordin, Abdul Rahman; Abdullah, Norbani; Balamurugan, S.

2015-09-01

The thermoelectric effect, also known as the Seebeck effect, describes the conversion of a temperature gradient into electricity. A Figure of Merit (ZT) is used to describe the thermoelectric ability of a material. It is directly dependent on its Seebeck coefficient and electrical conductivity, and inversely dependent on its thermal conductivity. There is usually a compromise between these parameters, which limit the performance of thermoelectric materials. The current achievement for ZT~2.2 falls short of the expected threshold of ZT=3 to allow its viability in commercial applications. In recent times, advances in organic thermoelectrics been significant, improving by over 3 orders of magnitude over a period of about 10 years. Liquid crystals are newly investigated as candidate thermoelectric materials, given their low thermal conductivity, inherent ordering, and in some cases, reasonable electrical conductivity. In this work the thermoelectric behaviour of a discotic liquid crystal, is discussed. The DLC was filled into cells coated with a charge injector, and an alignment of the columnar axis perpendicular to the substrate was allowed to form. This thermoelectric behavior can be correlated to the order-disorder transition. A reasonable thermoelectric power in the liquid crystal temperature regime was noted. In summary, thermoelectric liquid crystals may have the potential to be utilised in flexible devices, as a standalone power source.

Sexually Explicit Media on the Internet: A Content Analysis of Sexual Behaviors, Risk, and Media Characteristics in Gay Male Adult Videos

OpenAIRE

Downing, Martin J.; Schrimshaw, Eric W.; Antebi, Nadav; Siegel, Karolynn

2013-01-01

Recent research suggests that viewing sexually explicit media (SEM), i.e., adult videos, may influence sexual risk taking among men who have sex with men (MSM). Despite this evidence, very little is known about the content of gay male SEM on the Internet, including the prevalence of sexual risk behaviors and their relation to video- and performer-characteristics, viewing frequency, and favorability. The current study content analyzed 302 sexually explicit videos featuring male same-sex perfor...