Sample records for solid phase crystallization

  1. Modified phase-field-crystal model for solid-liquid phase transitions. (United States)

    Guo, Can; Wang, Jincheng; Wang, Zhijun; Li, Junjie; Guo, Yaolin; Tang, Sai


    A modified phase-field-crystal (PFC) model is proposed to describe solid-liquid phase transitions by reconstructing the correlation function. The effects of fitting parameters of our modified PFC model on the bcc-liquid phase diagram, numerical stability, and solid-liquid interface properties during planar interface growth are examined carefully. The results indicate that the increase of the correlation function peak width at k=k(m) will enhance the stability of the ordered phase, while the increase of peak height at k=0 will narrow the two-phase coexistence region. The third-order term in the free-energy function and the short wave-length of the correlation function have significant influences on the numerical stability of the PFC model. During planar interface growth, the increase of peak width at k=k(m) will decrease the interface width and the velocity coefficient C, but increase the anisotropy of C and the interface free energy. Finally, the feasibility of the modified phase-field-crystal model is demonstrated with a numerical example of three-dimensional dendritic growth of a body-centered-cubic structure.

  2. Polysilicon thin films fabricated by solid phase crystallization using reformed crystallization annealing technique

    Energy Technology Data Exchange (ETDEWEB)

    Tüzün Özmen, Ö., E-mail: [Department of Physics, Düzce University, 81620 Düzce (Turkey); Karaman, M. [GÜNAM, Middle East Technical University, 06800 Ankara (Turkey); Department of Micro and Nanotechnology, Middle East Technical University, 06531 Ankara (Turkey); Turan, R. [GÜNAM, Middle East Technical University, 06800 Ankara (Turkey); Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)


    In this work, a reformed crystallization annealing technique is presented for the solid phase crystallization (SPC) of amorphous silicon (a-Si) on SiN{sub x}-coated quartz substrate. This technique includes a two-step annealing process which consists of a low-temperature (475 °C) classical furnace annealing for nucleation of Si and a high-temperature (900 °C) grain growth process of polycrystalline silicon (poly-Si) during thermal annealing in classical tube furnace. The aim of this reformed two-step annealing technique is reducing the long (up to 48 h) crystallization annealing duration of single step annealing at low temperatures (∼ 600 °C) while maintaining the film quality, as low-temperature single step annealing, by using reformed technique. Continuous p-type poly-Si film was formed on quartz substrate thanks to exodiffusion of boron, which was deposited prior to a-Si, through Si film by thermal annealing. The stress and degree of crystallinity of the p-type poly-Si were studied by the micro-Raman Spectroscopy. The crystallization fraction value of 95% was deduced for annealed samples at 900 °C, independent from crystallization technique. On the other hand, the Raman analysis points out that compressive stress was induced by increasing the annealing duration at 900 °C. X-ray diffraction (XRD) analysis reveals that the preferred crystallite orientation of the films, independent from crystallization temperature and substrates, is <111>. Additionally, the average crystallite size calculated from XRD patterns increases from 69 Å to 165 Å by using reformed two-step annealing instead of single step annealing at 900 °C for 90 min. The exodiffusion of boron into the silicon film was deduced from secondary ion mass spectrometry (SIMS) analysis and the p{sup +}/p graded boron profile was obtained, which may result higher carrier diffusion length and longer carrier life time. Finally, the annealing duration dramatically decrease to 9 h by using reformed two

  3. Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope. (United States)

    Song, Ningfang; Ma, Kun; Jin, Jing; Teng, Fei; Cai, Wei


    A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10 -5 deg/√h.

  4. Modeling of Thermal Phase Noise in a Solid Core Photonic Crystal Fiber-Optic Gyroscope

    Directory of Open Access Journals (Sweden)

    Ningfang Song


    Full Text Available A theoretical model of the thermal phase noise in a square-wave modulated solid core photonic crystal fiber-optic gyroscope has been established, and then verified by measurements. The results demonstrate a good agreement between theory and experiment. The contribution of the thermal phase noise to the random walk coefficient of the gyroscope is derived. A fiber coil with 2.8 km length is used in the experimental solid core photonic crystal fiber-optic gyroscope, showing a random walk coefficient of 9.25 × 10−5 deg/√h.

  5. Zinc oxide crystal whiskers as a novel sorbent for solid-phase extraction of flavonoids. (United States)

    Wang, Licheng; Shangguan, Yangnan; Hou, Xiudan; Jia, Yong; Liu, Shujuan; Sun, Yingxin; Guo, Yong


    As a novel solid-phase extraction material, zinc oxide crystal whiskers were used to extract flavonoid compounds and showed good extraction abilities. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy and surface area/pore volume characterized the sorbent. The zinc oxide was packed into a solid-phase extraction micro-column and its extraction ability was evaluated by four model flavonoid compounds. The sample loading and elution parameters were optimized and the zinc oxide based analytical method for flavonoids was established. It showed that the method has wide linearities from 1 to 150μg/L and low limits of detection at 0.25μg/L. The relative standard deviations of a single column repeatability and column to column reproducibility were less than 6.8% and 10.6%. Several real samples were analyzed by the established method and satisfactory results were obtained. The interactions between flavonoids and zinc oxide were calculated and proved to be from the Van der Waals' forces between the 4p and 5d orbitals from zinc atom and the neighboring π orbitals from flavonoid phenyl groups. Moreover, the zinc oxide crystal whiskers showed good stability and could be reused more than 50 times under the operation conditions. This work proves that the zinc oxide crystal whiskers are a good candidate for flavonoids enrichment. Copyright © 2017. Published by Elsevier B.V.

  6. Molecular dynamics in perfluoro-n-eicosane. I. Solid phase behavior and crystal structures (United States)

    Schwickert, Heinz; Strobl, Gert; Kimmig, Martin


    Perfluoro-n-eicosane (n-C20F42) passes through three different solid modifications, called M(T200 K). Structures of the phases M and R were characterized by x-ray scattering experiments. Crystals are built up by rectangular layers. In modification M layers are set up by arrays of right-handed and left-handed (15/7-) helices in alternate succession. The unit cell is monoclinic (a=9.65 Å, b=5.70 Å, c=28.3 Å, and β=97°; space group Pa). In modification R molecules are highly mobile. There is no ordering with regard to the helix handedness. Molecules resemble cylindrical objects and are packed in a hexagonal dense mode. Regular layer stacking results in crystals with rhombohedral symmetry (a=b=5.70 Å, c=85.00 Å, γ=120°; space group R3¯m).

  7. Kinetics of the laser-induced solid phase crystallization of amorphous silicon-Time-resolved Raman spectroscopy and computer simulations (United States)

    Očenášek, J.; Novák, P.; Prušáková, L.


    This study demonstrates that a laser-induced crystallization instrumented with Raman spectroscopy is, in general, an effective tool to study the thermally activated crystallization kinetics. It is shown, for the solid phase crystallization of an amorphous silicon thin film, that the integral intensity of Raman spectra corresponding to the crystalline phase grows linearly in the time-logarithmic scale. A mathematical model, which assumes random nucleation and crystal growth, was designed to simulate the crystallization process in the non-uniform temperature field induced by laser. The model is based on solving the Eikonal equation and the Arhenius temperature dependence of the crystal nucleation and the growth rate. These computer simulations successfully approximate the crystallization process kinetics and suggest that laser-induced crystallization is primarily thermally activated.

  8. Automatic Stand Modeling of Casting Rate Influence on Solid Phase Growth of Round Ingot inside Crystallizer

    Directory of Open Access Journals (Sweden)

    A. N. Chichko


    Full Text Available The method of calculation and results of computer dynamics modeling of solid ingot skin in a crystallizer are presented in the paper. The paper shows influence of ingot drawing rate on dynamics of solid ingot skin growth in the continuous casting machine at steel grades used at Republic Unitary Enterprise «Belarussian Metallurgical Works» (BMZ.

  9. Advanced Si solid phase crystallization for vertical channel in vertical NANDs

    Directory of Open Access Journals (Sweden)

    Sangsoo Lee


    Full Text Available The advanced solid phase crystallization (SPC method using the SiGe/Si bi-layer structure is proposed to obtain high-mobility poly-Si thin-film transistors in next generation vertical NAND (VNAND devices. During the SPC process, the top SiGe thin film acts as a selective nucleation layer to induce surface nucleation and equiaxial microstructure. Subsequently, this SiGe thin film microstructure is propagated to the underlying Si thin film by epitaxy-like growth. The initial nucleation at the SiGe surface was clearly observed by in situ transmission electron microscopy (TEM when heating up to 600 °C. The equiaxial microstructures of both SiGe nucleation and Si channel layers were shown in the crystallized bi-layer plan-view TEM measurements. Based on these experimental results, the large-grained and less-defective Si microstructure is expected to form near the channel region of each VNAND cell transistor, which may improve the electrical characteristics.

  10. Kinetics of the laser-induced solid phase crystallization of amorphous silicon—Time-resolved Raman spectroscopy and computer simulations

    Energy Technology Data Exchange (ETDEWEB)

    Očenášek, J., E-mail:; Novák, P.; Prušáková, L.


    Highlights: • Mathematical model for crystallization in a non-uniform temp. field was designed. • Quantitative analyses of Raman spectra are presented. • Analyses of the crystallization kinetics using laser irradiation are introduced. • Laser-induced crystallization kinetics of a-Si thin film was analyzed in detail. - Abstract: This study demonstrates that a laser-induced crystallization instrumented with Raman spectroscopy is, in general, an effective tool to study the thermally activated crystallization kinetics. It is shown, for the solid phase crystallization of an amorphous silicon thin film, that the integral intensity of Raman spectra corresponding to the crystalline phase grows linearly in the time-logarithmic scale. A mathematical model, which assumes random nucleation and crystal growth, was designed to simulate the crystallization process in the non-uniform temperature field induced by laser. The model is based on solving the Eikonal equation and the Arhenius temperature dependence of the crystal nucleation and the growth rate. These computer simulations successfully approximate the crystallization process kinetics and suggest that laser-induced crystallization is primarily thermally activated.

  11. Phase field crystal simulation of stress induced localized solid-state amorphization in nanocrystalline materials (United States)

    Xi, Wen; Song, Xiaoqing; Hu, Shi; Chen, Zheng


    In this work, the phase field crystal (PFC) method is used to study the localized solid-state amorphization (SSA) and its dynamic transformation process in polycrystalline materials under the uniaxial tensile deformation with different factors. The impacts of these factors, including strain rates, temperatures and grain sizes, are analyzed. Kinetically, the ultra-high strain rate causes the lattice to be seriously distorted and the grain to gradually collapse, so the dislocation density rises remarkably. Therefore, localized SSA occurs. Thermodynamically, as high temperature increases the activation energy, the atoms are active and prefer to leave the original position, which induce atom rearrangement. Furthermore, small grain size increases the percentage of grain boundary and the interface free energy of the system. As a result, Helmholtz free energy increases. The dislocations and Helmholtz free energy act as the seed and driving force for the process of the localized SSA. Also, the critical diffusion-time step and the percentage of amorphous region areas are calculated. Through this work, the PFC method is proved to be an effective means to study localized SSA under uniaxial tensile deformation.

  12. Statistical theory of solid and liquid crystals (United States)

    Bazarov, I. P.; Gevorkian, E. V.

    The statistical theory of solid and liquid crystals is presented with allowance for many-particle interactions. Statistical variational principles and various representations of Bogoliubov's equations are examined, and the thermodynamic properties of anharmonic solid crystals and microscopic models of liquid crystals are then discussed. Attention is given to the application of the theory developed here to the description of phase transitions in solid and liquid crystals. The stability of the far-range orientational and translational orders in solid and liquid crystals is discussed using a continuum model of liquid crystals and rigorous methods of statistical mechanics based on Bogoliubov's inequality.

  13. Solid-state 51V MAS NMR spectroscopy determines component concentration and crystal phase in co-crystallised mixtures of vanadium complexes

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Hazell, Alan Charles; Skibsted, Jørgen Bengaard


    resonances are sensitive to intermolecular interactions specific to each crystal phase. The solid-state V-51 MAS NMR spectroscopic data show that the different phases do not co-precipitate but the concentration of the solute (which can be either 1 or 2) can vary. Thus co-crystallised mixtures of 1 and 2 can...

  14. Phase diagrams and crystal growth (United States)

    Venkrbec, Jan


    Phase diagrams are briefly treated as generalized property-composition relationships, with respect to crystal technology optimization. The treatment is based on mutual interaction of three systems related to semiconductors: (a) the semiconducting material systems, (b0 the data bank, (c) the system of crystallization methods. A model is proposed enabling optimatization on the path from application requirements to the desired material. Further, several examples of the selection as to the composition of LED and laser diode material are given. Some of molten-solution-zone methods are being successfully introduced for this purpose. Common features of these methods, the application of phase diagrams, and their pecularities compared with other crystallization methods are illustrated by schematic diagrams and by examples. LPE methods, particularly the steady-state LPE methods such as Woodall's ISM and Nishizawa's TDM-CVP, and the CAM-S (Crystallization Method Providing Composition Autocontrol in Situ) have been chosen as examples. Another approach of exploiting phase diagrams for optimal material selection and for determination of growth condition before experimentation through a simple calculation is presented on InP-GaP solid solutions. Ternary phase diagrams are visualized in space through calculation and constructions based on the corresponding thermodynamic models and anaglyphs. These make it easy to observe and qualitatively analyze the crystallization of every composition. Phase diagrams can be also used as a powerful tool for the deduction of new crystallization methods. Eutectic crystallization is an example of such an approach where a modified molten-solution-zone method can give a sandwich structure with an abrupt concentration change. The concentration of a component can range from 0 to 100% in the different solid phases.

  15. Crystal phase transition in LixNa1-xGdF4 solid solution nanocrystals - Tuning of optical properties

    KAUST Repository

    Bański, Mateusz


    The influence of precursor composition on the crystallization of LixNa1-xGdF4 is investigated and discussed. Nanocrystals are prepared from the thermal decomposition of trifluoroacetates in the presence of trioctylphosphine oxide to provide control over particle size. A crystal phase transition from hexagonal to cubic and to tetragonal is observed by increasing lithium trifluoroacetate (Li-TFA) in the solution. Controlling the composition of LixNa1-xGdF4 nanocrystals results in modified crystal field symmetry and emission properties from doped europium (Eu3+) ions. We report that for lithium (Li+) substitution <15%, the hexagonal crystal field is preferred, while the Eu3+ emission is already tuned, whereas at higher Li+ substitution, a phase change takes place and the number of crystalline matrix defects increases which is reflected in the optical properties of Eu3+. From Eu3+ emission properties, the optimum Li+ content is determined to be ∼6.2% in the prepared LixNa1-xGdF4 nanocrystals.

  16. Polypyrrole-magnetite dispersive micro-solid-phase extraction combined with ultraviolet-visible spectrophotometry for the determination of rhodamine 6G and crystal violet in textile wastewater. (United States)

    Kamaruddin, Amirah Farhan; Sanagi, Mohd Marsin; Wan Ibrahim, Wan Aini; Md Shukri, Dyia S; Abdul Keyon, Aemi S


    Polypyrrole-magnetite dispersive micro-solid-phase extraction method combined with ultraviolet-visible spectrophotometry was developed for the determination of selected cationic dyes in textile wastewater. Polypyrrole-magnetite was used as adsorbent due to its thermal stability, magnetic properties, and ability to adsorb Rhodamine 6G and crystal violet. Dispersive micro-solid-phase extraction parameters were optimized, including sample pH, adsorbent amount, extraction time, and desorption solvent. The optimum polypyrrole-magnetite dispersive micro-solid phase-extraction conditions were sample pH 8, 60 mg polypyrrole-magnetite adsorbent, 5 min of extraction time, and acetonitrile as the desorption solvent. Under the optimized conditions, the polypyrrole-magnetite dispersive micro-solid-phase extraction with ultraviolet-visible method showed good linearity in the range of 0.05-7 mg/L (R 2  > 0.9980). The method also showed a good limit of detection for the dyes (0.05 mg/L) and good analyte recoveries (97.4-111.3%) with relative standard deviations textile wastewater samples where the concentration found was 1.03 mg (RSD ±7.9%) and 1.13 mg/L (RSD ± 4.6%) for Rhodamine 6G and crystal violet, respectively. It can be concluded that this method can be adopted for the rapid extraction and determination of dyes at trace concentration levels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Solid phase transformations II

    CERN Document Server

    Čermák, J


    This topical volume includes ten invited papers that cover selected areas of the field of solid phase transformations. The first two contributions represent a burgeoning branch; that of the computer simulation of physical phenomena. The following three articles deal with the thermodynamics of phase transformations as a basic theory for describing the phenomenology of phase changes in matter. The next paper describes the interconnections between structural stability and the electronic structure of phases. Two further articles are devoted to displacive transformations; a field where there are ma

  18. Low-temperature (<200 oC solid-phase crystallization of high substitutional Sn concentration (∼10% GeSn on insulator enhanced by weak laser irradiation

    Directory of Open Access Journals (Sweden)

    Kenta Moto


    Full Text Available Low temperature (8% on insulating substrates is essential to realize next generation flexible electronics. To achieve this, a growth method of high quality GeSn films on insulating substrates by combination of laser irradiation and subsequent thermal annealing is developed. Here, the laser fluence is chosen as weak, which is below the critical fluence for crystallization of GeSn. It is clarified that for samples irradiated with weak laser fluence, complete crystallization of GeSn films is achieved by subsequent thermal annealing at ∼170 oC without incubation time. In addition, the quality of GeSn films obtained by this method is higher compared with conventional growth techniques such as melting growth by pulsed laser annealing or solid-phase crystallization (SPC without pre-laser irradiation. Substitutional Sn concentrations in the grown layers estimated by Raman spectroscopy measurements are 8-10%, which far exceed thermal equilibrium solid-solubility of Sn in Ge (∼2%. These phenomena are explained by generation of a limited number of nuclei by weak laser irradiation and lateral SPC by subsequent thermal annealing. This method will facilitate realization of next-generation high performance devices on flexible insulating substrates.

  19. Solid phase transformations

    CERN Document Server

    Čermák, J


    This special-topic book, devoted to ""Solid Phase Transformations"" , covers a broad range of phenomena which are of importance in a number of technological processes. Most commercial alloys undergo thermal treatment after casting, with the aim of imparting desired compositions and/or optimal morphologies to the component phases. In spite of the fact that the topic has lain at the center of physical metallurgy for a long time, there are numerous aspects which are wide open to potential investigative breakthroughs. Materials with new structures also stimulate research in the field, as well as n

  20. Impact of solid-phase crystallization of amorphous silicon on the chemical structure of the buried Si/ZnO thin film solar cell interface

    Energy Technology Data Exchange (ETDEWEB)

    Bar, M.; Wimmer, M.; Wilks, R. G.; Roczen, M.; Gerlach, D.; Ruske, F.; Lips, K.; Rech, B.; Weinhardt, L.; Blum, M.; Pookpanratana, S.; Krause, S.; Zhang, Y.; Heske, C.; Yang, W.; Denlinger, J. D.


    The chemical interface structure between phosphorus-doped hydrogenated amorphous silicon and aluminum-doped zinc oxide thin films is investigated with soft x-ray emission spectroscopy (XES) before and after solid-phase crystallization (SPC) at 600C. In addition to the expected SPC-induced phase transition from amorphous to polycrystalline silicon, our XES data indicates a pronounced chemical interaction at the buried Si/ZnO interface. In particular, we find an SPC-enhanced formation of Si-O bonds and the accumulation of Zn in close proximity to the interface. For an assumed closed and homogeneous SiO2 interlayer, an effective thickness of (5+2)nm after SPC could be estimated.

  1. Phase diagram of boron crystals (United States)

    Shirai, Koun


    The current status of study on the phase diagram of boron is given from the theoretical viewpoint. Boron is the last elemental crystal whose phase diagram is missing. In the last decade, several new structures of boron allotropes were found, while some were disproven. Presently, even the number of allotropes of boron is uncertain. A simple reason for this is that there are many and complicated structures, and some are minimally different from the others. A theoretical study thus requires very high accuracy. The difficulty, however, is not merely a technical difficulty of computational scale. The physics involved is quite different from what is obtained by band theory, which is the most successful theory of solids. It is only recent that a fundamental problem of metal/insulator has been solved. We come to know that the interrelationships between nonstoichiometry, partially occupied sites, and the balance of intra/inter-icosahedral bonding, which were considered to be uncorrelated properties, inevitably determine the relative stability of various structures. The configuration of the defects in boron crystals is not capricious but there is some correlation among the defects. Many problems were solved on this ground, and contributed to the creation of the phase diagram. However, there are still many unsolved problems and some newly arose. In particular, for the tetragonal phase, sharp discrepancies are present in both experiment and theory. Thus, the problem of tetragonal phase is described in more detail. From the viewpoint of material research, the phase diagram provides the basis for searching new materials. State-of-the-art methods of structural prediction have stimulated researchers’ interest.

  2. Solid-phase microextraction

    DEFF Research Database (Denmark)

    Nilsson, Torben

    and organophosphate pesticides and triazine herbicides together with their metabolites in aqueous samples. SPME combined with gas chromatography proved to be a precise, accurate and sensitive technique for water analysis. Also SPME combined with high performance liquid chromatography was tested, and a method......The objective of this study has been to develop new analytical methods using the rapid, simple and solvent-free extraction technique solid-phase microextraction (SPME) for the quantitative analysis of organic pollutants at trace level in drinking water and environmental samples. The dynamics...

  3. Determination of 5-hydroxymethylfurfural in honey, using headspace-solid-phase microextraction coupled with a polyoxometalate-coated piezoelectric quartz crystal. (United States)

    Veríssimo, Marta I S; Gamelas, José A F; Evtuguin, Dmitry V; Gomes, M Teresa S R


    High concentrations of 5-hydroxymethylfurfural (HMF) in honey provide an indication of overheating under inappropriate storage conditions or aging. Conventional methods for determining HMF are cumbersome and require expensive equipment or hazardous reagents. Hence the aim of this study was to propose a new analytical tool for HMF determination in honey, using a low cost acoustic wave sensor. Volatile organic compounds (VOCs) of honey samples were extracted, using the solid phase microextraction (SPME) technique, and HMF was quantified, using a piezoelectric quartz crystal with gold electrodes coated with a layer of decamolybdodivanado phosphoric acid, sensitive to HMF. The reliability of the proposed method was confirmed after comparing the results of HMF quantification with those obtained by the conventional spectrophotometric White method, and no statistical differences were found (α=0.05). Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Does the solid-liquid crystal phase transition provoke the spin-state change in spin-crossover metallomesogens? (United States)

    Seredyuk, M; Gaspar, A B; Ksenofontov, V; Galyametdinov, Y; Kusz, J; Gütlich, P


    Three types of interplay/synergy between spin-crossover (SCO) and liquid crystalline (LC) phase transitions can be predicted: (i) systems with coupled phase transitions, where the structural changes associated to the CrLC phase transition drives the spin-state transition, (ii) systems where both transitions coexist in the same temperature region but are not coupled, and (iii) systems with uncoupled phase transitions. Here we present a new family of Fe(II) metallomesogens based on the ligand tris[3-aza-4-((5-C(n))(6-R)(2-pyridyl))but-3-enyl]amine, with C(n) = hexyloxy, dodecyloxy, hexadecyloxy, octadecyloxy, eicosyloxy, R = hydrogen or methyl (C(n)-trenH or C(n)-trenMe), which affords examples of systems of types i, ii, and iii. Self-assembly of the ligands C(n)-trenH and C(n)-trenMe with Fe(A)2 x xH2O salts have afforded a family of complexes with general formula [Fe(C(n)-trenR)](A)2 x sH2O (s > or = 0), with A = ClO4(-), F-, Cl-, Br- and I-. Single-crystal X-ray diffraction measurements have been performed on two derivatives of this family, named as [Fe(C6-trenH)](ClO4)2 (C(6)-1) and [Fe(C6-trenMe)](ClO4)2 (C(6)-2), at 150 K for C(6)-1 and at 90 and 298 K for C(6)-2. At 150 K, C(6)-1 displays the triclinic space group P, whereas at 90 and at 298 K C(6)-2 adopts the monoclinic P2(1)/c space group. In both compounds the iron atoms adopt a pseudo-octahedral symmetry and are surrounded by six nitrogen atoms belonging to imino groups and pyridines of the ligands C(n)-trenH and C(n)-trenMe. The average Fe(II)-N bonds (1.963(2) A) at 150 K denote that C(6)-1 is in the low-spin (LS) state. For C(6)-2 the average Fe(II)-N bonds (2.007(1) A) at 90 K are characteristic of the LS state, while at 298 K they are typical for the high-spin (HS) state (2.234(3) A). Compound C(6)-1 and [Fe(C18-trenH)](ClO4)2 (C(18)-1) adopts the LS state in the temperature region between 10 and 400 K, while compound C(6)-2 and [Fe(Cn-trenMe)](ClO4)2 (n = 12 (C(12)-2), 18 (C(18)-2)) exhibit spin

  5. Solid state single crystal growth of three-dimensional faceted LaFeAsO crystals (United States)

    Kappenberger, Rhea; Aswartham, Saicharan; Scaravaggi, Francesco; Blum, Christian G. F.; Sturza, Mihai I.; Wolter, Anja U. B.; Wurmehl, Sabine; Büchner, Bernd


    Solid state single crystal growth (SSCG) is a crystal growth technique where crystals are grown from a polycrystalline matrix. Here, we present single crystals of the iron pnictide LaFeAsO grown via SSCG using NaAs as a liquid phase to aid crystallization. The size of the as-grown crystals are up to 2 × 3 × 0.4 mm3. Typical for this method, but very uncommon for crystals of the pnictide superconductors and especially for the oxypnictides, the crystals show pronounced facets caused by considerable growth in c direction. The crystals were characterized regarding their composition, structure, magnetic, and thermodynamic properties. This sets the stage for further measurements for which single crystals are crucial such as any c axis and reciprocal space dependent measurements.

  6. Solid phase protein chemical synthesis. (United States)

    Raibaut, Laurent; El Mahdi, Ouafâa; Melnyk, Oleg


    The chemical synthesis of peptides or small proteins is often an important step in many research projects and has stimulated the development of numerous chemical methodologies. The aim of this review is to give a substantial overview of the solid phase methods developed for the production or purification of polypeptides. The solid phase peptide synthesis (SPPS) technique has facilitated considerably the access to short peptides (peptides have stimulated the development of solid phase covalent or non-covalent capture purification methods. The power of the native chemical ligation (NCL) reaction for protein synthesis in aqueous solution has also been adapted to the solid phase by the combination of novel linker technologies, cysteine protection strategies and thioester or N,S-acyl shift thioester surrogate chemistries. This review details pioneering studies and the most recent publications related to the solid phase chemical synthesis of large peptides and proteins.

  7. An Investigation into the Polymorphism and Crystallization of Levetiracetam and the Stability of its Solid Form. (United States)

    Xu, Kailin; Xiong, Xinnuo; Guo, Liuqi; Wang, Lili; Li, Shanshan; Tang, Peixiao; Yan, Jin; Wu, Di; Li, Hui


    Levetiracetam (LEV) crystals were prepared using different solvents at different temperatures. The LEV crystals were systematically characterized by X-ray powder diffraction (XRPD) and morphological analysis. The results indicated that many kinds of crystal habits exist in a solid form of LEV. To investigate the effects of LEV concentration, crystallization temperature, and crystallization type on crystallization and solid phase transformation of LEV, multiple methods were performed for LEV aqueous solution to determine if a new solid form exists in solid-state LEV. However, XRPD data demonstrate that the LEV solid forms possess same spatial arrangements that are similar to the original solid form. This result indicates that the LEV concentration, crystallization temperature, and crystallization type in aqueous solution have no influence on the crystallization and solid phase transformation of LEV. Moreover, crystallization by sublimation, melt cooling, and quench cooling, as well as mechanical effect, did not result in the formation of new LEV solid state. During melt cooling, the transformation of solid form LEV is a direct process from melting amorphous phase to the original LEV crystal phase, and the conversion rate is very quick. In addition, stability investigation manifested that LEV solid state is very stable under various conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  8. Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Rai, R.N., E-mail: [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Kant, Shiva; Reddi, R.S.B. [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Ganesamoorthy, S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Gupta, P.K. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)


    Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

  9. Photoinduced crystal-to-liquid phase transitions of azobenzene derivatives and their application in photolithography processes through a solid-liquid patterning. (United States)

    Norikane, Yasuo; Uchida, Emi; Tanaka, Satoko; Fujiwara, Kyoko; Koyama, Emiko; Azumi, Reiko; Akiyama, Haruhisa; Kihara, Hideyuki; Yoshida, Masaru


    The direct and reversible transformation of matter between the solid and liquid phases by light at constant temperature is of great interest because of its potential applications in various manufacturing settings. We report a simple molecular design strategy for the phase transitions: azobenzenes having para-dialkoxy groups with a methyl group at the meta-position. The photolithography processes were demonstrated using the azobenzene as a photoresist in a single process combining development and etching of a copper substrate.

  10. Solid-phase peptide synthesis

    DEFF Research Database (Denmark)

    Jensen, Knud Jørgen


    This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective.......This chapter provides an introduction to and overview of peptide chemistry with a focus on solid-phase peptide synthesis. The background, the most common reagents, and some mechanisms are presented. This chapter also points to the different chapters and puts them into perspective....

  11. Multiple solid-phase microextraction

    NARCIS (Netherlands)

    Koster, EHM; de Jong, GJ


    Theoretical aspects of multiple solid-phase microextraction are described and the principle is illustrated with the extraction of lidocaine from aqueous solutions. With multiple extraction under non-equilibrium conditions considerably less time is required in order to obtain an extraction yield that

  12. Rapid magnetic solid-phase extraction based on monodisperse magnetic single-crystal ferrite nanoparticles for the determination of free fatty acid content in edible oils. (United States)

    Wei, Fang; Zhao, Qin; Lv, Xin; Dong, Xu-Yan; Feng, Yu-Qi; Chen, Hong


    This study proposes a rapid magnetic solid-phase extraction (MSPE) based on monodisperse magnetic single-crystal ferrite (Fe(3)O(4)) nanoparticles (NPs) for determining the quantities of eight free fatty acids (FFAs), including palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3), arachidic acid (C20:0), eicosenoic acid (C20:1), and behenic acid (C22:0) in oil. The amine-functionalized mesoporous Fe(3)O(4) magnetic NPs were applied as a sorbent for MSPE of FFAs from oil samples in a process that is based on hydrophilic interaction. The extraction can be completed rapidly in a dispersive mode with the aid of vigorous vortex. Additional tedious processing steps such as centrifugation and evaporation of organic solvent were not necessary with this procedure. Furthermore, esterification of FFAs can be accomplished during the desorption procedure by using methanol/sulfuric acid (99:1, v/v) as the desorption solvent. Several parameters affecting the extraction efficiency were investigated, including the matrix solvent for extraction, the desorption solvent and desorption time, and the amount of sorbent and extraction time. The pretreatment process was rapid under optimal conditions, being accomplished within 15 min. When coupled with gas chromatography-flame ionization detection (GC-FID), a rapid, simple, and convenient MSPE-GC-FID method for the determination of FFAs in oil samples was established with a total analysis time within 25 min. The limits of detection for the target FFAs were found to be 7.22-26.26 ng/mL. Recoveries in oil samples were in the range of 81.33-117.75%, with RSDs of <6.4% (intraday) and <6.9% (interday). This method was applied successfully to the analysis of dynamic FFA formation in four types of edible oils subjected to an accelerated storage test. The simple, rapid, and cost-effective method developed in the current study offers a potential application for the extraction and

  13. Surface Premelting Coupled with Bulk Phase Transitions in Colloidal Crystals (United States)

    Li, Bo; Wang, Feng; Zhou, Di; Cao, Xin; Peng, Yi; Ni, Ran; Liao, Maijia; Han, Yilong


    Colloids have been used as outstanding model systems for the studies of various phase transitions in bulk, but not at interface yet. Here we obtained equilibrium crystal-vapor interfaces using tunable attractive colloidal spheres and studied the surface premelting at the single-particle level by video microscopy. We found that monolayer crystals exhibit a bulk isostructural solid-solid transition which triggers the surface premelting. The premelting is incomplete due to the interruption of a mechanical-instability-induced bulk melting. By contrast, two- or multilayer crystals do not have the solid-solid transition and the mechanical instability, hence they exhibit complete premelting with divergent surface-liquid thickness. These novel interplays between bulk and surface phase transitions cast new lights for both types of transitions.

  14. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber. (United States)

    Zito, Gianluigi; Pissadakis, Stavros


    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a prepolymer/liquid crystal solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG, are discussed. Experimental data presented here demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal phase separation inside the PCF capillaries is examined using scanning electron microscopy, and is discussed further.

  15. Investigation of binary solid phases by calorimetry and kinetic modelling

    NARCIS (Netherlands)

    Matovic, M.


    The traditional methods for the determination of liquid-solid phase diagrams are based on the assumption that the overall equilibrium is established between the phases. However, the result of the crystallization of a liquid mixture will typically be a non-equilibrium or metastable state of the

  16. Solid phase syntheses of oligoureas

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, K.; Linthicum, D.S.; Russell, D.H.; Shin, H.; Shitangkoon, A.; Totani, R.; Zhang, A.J.; Ibarzo, J. [Texas A& M Univ., College Station, TX (United States)


    Isocyanates 7 were formed from monoprotected diamines 3 or 6, which in turn can be easily prepared from commercially available N-BOC- or N-FMOC-protected amino acid derivatives. Isocyanates 7, formed in situ, could be coupled directly to a solid support functionalized with amine groups or to amino acids anchored on resins using CH{sub 2}Cl{sub 2} as solvent and an 11 h coupling time at 25 {degree}C. Such couplings afforded peptidomimetics with an N-phthaloyl group at the N-terminus. The optimal conditions identified for removal of the N-phthaloyl group were to use 60% hydrazine in DMF for 1-3 h. Several sequences of amino acids coupled to ureas (`peptidic ureas`) and of sequential urea units (`oligoureas`) were prepared via solid phase syntheses and isolated by HPLC. Partition coefficients were measured for two of these peptidomimetics, and their water solubilities were found to be similar to the corresponding peptides. A small library of 160 analogues of the YGGFL-amide sequence was prepared via Houghten`s tea bag methodology. This library was tested for binding to the anti-{beta}-endorphin monoclonal antibody. Overall, this paper describes methodology for solid phase syntheses of oligourea derivatives with side chains corresponding to some of the protein amino acids. The chemistry involved is ideal for high-throughput syntheses and screening operations. 51 refs., 3 figs., 2 tabs.

  17. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber

    CERN Document Server

    Zito, Gianluigi


    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG lead to high thermal and bending sensitivities. The microscopic behavior of the polymer/liquid crystal phase separation inside the PCF capillaries is examined using scanning electron microscopy, while further discussed.

  18. Solid phase microextraction field kit (United States)

    Nunes, Peter J.; Andresen, Brian D.


    A field kit for the collection, isolation and concentration of trace amounts of high explosives (HE), biological weapons (BW) and chemical weapons (CW) residues in air, soil, vegetation, swipe, and liquid samples. The field kit includes a number of Solid Phase Microextraction (SPME) fiber and syringe assemblies in a hermetically sealed transportation container or tubes which includes a sampling port, a number of extra SPME fiber and syringe assemblies, the fiber and syringe assemblies including a protective cap for the fiber, and an extractor for the protective cap, along with other items including spare parts, protective glove, and an instruction manual, all located in an airtight container.

  19. Solid Phase versus Solution Phase Synthesis of Heterocyclic Macrocycles


    McAlpine, Shelli R.; Seong Jong Kim


    Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A) confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved...

  20. Solid Phase Characterization of Solids Recovered from Failed Sluicer Arm

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, Gary A. [Hanford Site (HNF), Richland, WA (United States)


    The Enclosure to this memo discusses the solid phase characterization of a solid sample that was retrieved from the single-shell Tank 241-C-111 extended reach sluicer #2. This sluicer, removed from riser #3 on September 25, 2014, was found to have approximately 0.4 gallons of solid tank waste adhering to the nozzle area.

  1. Solid Phase versus Solution Phase Synthesis of Heterocyclic Macrocycles

    Directory of Open Access Journals (Sweden)

    Shelli R. McAlpine


    Full Text Available Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved relatively straightforward. Given the ease with which the oxazole Ustat A precursor is formed via our solid phase approach, this route is amenable to rapid analog synthesis.

  2. Solid phase versus solution phase synthesis of heterocyclic macrocycles. (United States)

    Kim, Seong Jong; McAlpine, Shelli R


    Comparing a solution phase route to a solid phase route in the synthesis of the cytotoxic natural product urukthapelstatin A (Ustat A) confirmed that a solid phase method is superior. The solution phase approach was tedious and involved cyclization of a ridged heterocyclic precursor, while solid phase allowed the rapid generation of a flexible linear peptide. Cyclization of the linear peptide was facile and subsequent generation of three oxazoles located within the structure of Ustat A proved relatively straightforward. Given the ease with which the oxazole Ustat A precursor is formed via our solid phase approach, this route is amenable to rapid analog synthesis.

  3. A comparison of observables for solid-solid phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Smilowitz, Laura B [Los Alamos National Laboratory; Henson, Bryan F [Los Alamos National Laboratory; Romero, Jerry J [Los Alamos National Laboratory


    The study of solid-solid phase transformations is hindered by the difficulty of finding a volumetric probe to use as a progress variable. Solids are typically optically opaque and heterogeneous. Over the past several years, second harmonic generation (SHG) has been used as a kinetic probe for a solid-solid phase transition in which the initial and final phases have different symmetries. Bulk generation of SHG is allowed by symmetry only in noncentrosymmetric crystallographic space groups. For the organic energetic nitramine octahydro-1,3 ,5,7 -tetranitro-1,3 ,5,7 -tatrazocine (HMX), the beta phase is centro symmetric (space group P2{sub 1}/c) and the delta phase iS noncentrosymmetric (space group P6{sub 1}22) making SHG an extremely sensitive, essentially zero background probe of the phase change progress. We have used SHG as a tool to follow the progress of the transformation from beta to delta phase during the solid-solid transformation. However, kinetic models of the transformation derived using different observables from several other groups have differed, showing later onset for the phase change and faster progression to completion. In this work, we have intercompared several techniques to understand these differences. The three techniques discussed are second harmonic generation, Raman spectroscopy, and differential scanning calorimetry (DSC). The progress of the beta to delta phase transition in HMX observed with each of these different probes will be discussed and advantages and disadvantages of each technique described. This paper compares several different observables for use in measuring the kinetics of solid-solid phase transitions. Relative advantages and disadvantages for each technique are described and a direct comparison of results is made for the beta to delta polymorphic phase transition of the energetic nitramine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tatrazocine.

  4. Fast Analysis of Water Samples for Trace Amount of Crystal Violet Dye Based on Solid Phase Extraction Using Nanoporous SBA-3 prior to Determination by Fiber Optic-Linear Array Detection Spectrophotometry

    Directory of Open Access Journals (Sweden)

    Azam Azarkohan


    Full Text Available A solid phase preconcentration procedure using SBA-3 nanosorbent for the fast separation and preconcentration of crystal violet (CV in water samples by fiber optic-linear array detection spectrophotometry (FO-LADS is presented. Experimental parameters including pH, sample volume, amount of sorbent, type, volume, and concentration of eluent that affect the recovery of crystal violet have been optimized. Under optimized experimental conditions, analytical parameters including limit of detection, linear working range, and relative standard deviation have also been determined. A preconcentration factor of 200 was achieved in this method. In the initial solution, the detection limit for CV was found as 1.3 μg L−1. Under optimal conditions maximum adsorption capacity was obtained as 344.83 mg g−1. Also, the relative standard deviation was less than ±1.3% (n=5. The presented procedure was applied to the determination of crystal violet in water samples (fish, fish farming water, and river water with good results.

  5. Kinetics of Solid-Solid Phase Transition in Iron (u)

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, Cynthia, L [Los Alamos National Laboratory


    Previously, dynamic experiments on iron have observed a non-zero transition time and width in the solid-solid {alpha}-{var_epsilon} phase transition. Using Proton Radiography at the los Alamos Neutron Science Center, we have performed plate impact experiments on iron to further study the {alpha}-{var_epsilon} phase transition which occurs at 13GPa. A 40mm bore powder gun was coupled to a proton radiography beam line and imaging system and synchronized to the impact of the projectile on the target sample with the proton beam pattern. A typical experimental configuration for the iron study, as shown below in 3 color-enhanced radiographs, is a 40mm diameter aluminum sabot impacting a 40mm diameter of polycrystalline ARMCO iron. The iron is backed by a sapphire optical window for velocimetry measurements. The aluminum flyer on the left of the iron is barely visible for visual display purposes. Direct density jumps were measured which corresponded to calculations to within 1% using a Wondy multi-phase equation of state model. In addition, shock velocities were measured using an edge fitting technique and followed that edge movement from radiograph to radiograph, where rad iographs are separated in time by 500 ns. Preliminary measurements give a shock velocity (P1 wave) of 5.251 km/s. The projectile velocity was 0.725 km/s which translate to a peak stress of 17.5 GPa. Assuming the P1 wave is instantaneous, we are able to calibrate the chromatic, motion, object and camera blur by measuring the width of the P1 wave. This approximation works in this case since each of the two density jumps are small compared to the density of the object. Subtracting the measured width of the P1 wave in quadrature from the width of the P2 wave gives a preliminary measurement of the transition length of 265 {micro}m. Therefore, a preliminary measured phase transition relaxation time {tau} = transition length/u{sub s} = 265 {micro}m/5.251 km/s = 50 ns. Both Boettger1 & Jensen2 conclude that

  6. "Two-dimensional" molecularly imprinted solid-phase extraction coupled with crystallization and high performance liquid chromatography for fast semi-preparative purification of tannins from pomegranate husk extract. (United States)

    Sun, Guangying; Liu, Yanfang; Ahat, Hasanjan; Shen, Aijin; Liang, Xinmiao; Xue, Xingya; Luo, Yuqin; Yang, Jian; Liu, Zhao-Sheng; Aisa, Haji Akber


    In this study, "two dimensional" molecularly imprinted solid-phase extraction (2D-MIP-SPE) of semi-preparative grade was constructed to fast purify ellagitannins in pomegranate husk extract with the help of crystallization and reverse-phase liquid chromatgoraphy (RPLC). Ellagic acid and punicalagin imprinted polymers were synthesized in batch mode and two semi-preparative MIP-SPE columns were individually packed. After investigaing "functional complementation", 2D-MIP-SPE was constructed using ellagic acid MIP and punicalagin MIP-SPE as the first and second dimension, respectively. Then, pomegranate husk extract was fast divided into four fractions individually enriching in ellagic acid, granatin A, punicalagin and ellagic acid glucoside by 2D-MIP-SPE. With the aid of crystallization and RPLC, ellagic acid (13.5mg) and punicalagin (53.4mg) were fast obtained in 30min. Ellagic acid glucoside was purified to the purity near 100% with a recovery of 86.1%. Granatin A (92%) was directly obtained by 2D-MIP-SPE with the recovery of 81.8%. All above indicated that 2D-MIP-SPE was highly efficient in natural product purification. The concept of "functional complementation" was expected to be a useful tool in the construction of 2D-MIP-SPE. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Crystal-liquid-gas phase transitions and thermodynamic similarity

    CERN Document Server

    Skripov, Vladimir P; Schmelzer, Jurn W P


    Professor Skripov obtained worldwide recognition with his monograph ""Metastable liquids"", published in English by Wiley & Sons. Based upon this work and another monograph published only in Russia, this book investigates the behavior of melting line and the properties of the coexisting crystal and liquid phase of simple substances across a wide range of pressures, including metastable states of the coexisting phases. The authors derive new relations for the thermodynamic similarity for liquid-vapour phase transition, as well as describing solid-liquid, liquid-vapor and liquid-liquid phase tra

  8. Formamidinium iodide: crystal structure and phase transitions

    Directory of Open Access Journals (Sweden)

    Andrey A. Petrov


    Full Text Available At a temperature of 100 K, CH5N2+·I− (I, crystallizes in the monoclinic space group P21/c. The formamidinium cation adopts a planar symmetrical structure [the r.m.s. deviation is 0.002 Å, and the C—N bond lengths are 1.301 (7 and 1.309 (8 Å]. The iodide anion does not lie within the cation plane, but deviates from it by 0.643 (10 Å. The cation and anion of I form a tight ionic pair by a strong N—H...I hydrogen bond. In the crystal of I, the tight ionic pairs form hydrogen-bonded zigzag-like chains propagating toward [20-1] via strong N—H...I hydrogen bonds. The hydrogen-bonded chains are further packed in stacks along [100]. The thermal behaviour of I was studied by different physicochemical methods (thermogravimetry, differential scanning calorimetry and powder diffraction. Differential scanning calorimetry revealed three narrow endothermic peaks at 346, 387 and 525 K, and one broad endothermic peak at ∼605 K. The first and second peaks are related to solid–solid phase transitions, while the third and fourth peaks are attributed to the melting and decomposition of I. The enthalpies of the phase transitions at 346 and 387 K are estimated as 2.60 and 2.75 kJ mol−1, respectively. The X-ray powder diffraction data collected at different temperatures indicate the existence of I as the monoclinic (100–346 K, orthorhombic (346–387 K and cubic (387–525 K polymorphic modifications.

  9. Fmoc Solid-Phase Peptide Synthesis. (United States)

    Hansen, Paul R; Oddo, Alberto


    Synthetic peptides are important as drugs and in research. Currently, the method of choice for producing these compounds is solid-phase peptide synthesis. In this nonspecialist review, we describe the scope and limitations of Fmoc solid-phase peptide synthesis. Furthermore, we provide a detailed protocol for Fmoc peptide synthesis.

  10. Optical phase response to temperature in a hollow-core photonic crystal fiber. (United States)

    Meiselman, Seth; Cranch, Geoffrey A


    Analysis of previous measurements of thermal phase sensitivity in hollow core photonic crystal fibers is presented with additional new corroborating measurements, resolving a discrepancy in previously reported results. We extend an existing derivation of thermo-mechanical phase sensitivity in solid- and hollow-core photonic crystal fiber to also include kagome lattice photonic crystal fibers. Measured thermal phase response is shown to agree with theoretical prediction to within a few percent.

  11. A method of solid-solid phase equilibrium calculation by molecular dynamics. (United States)

    Karavaev, A V; Dremov, V V


    A method for evaluation of solid-solid phase equilibrium curves in molecular dynamics simulation for a given model of interatomic interaction is proposed. The method allows to calculate entropies of crystal phases and provides an accuracy comparable with that of the thermodynamic integration method by Frenkel and Ladd while it is much simpler in realization and less intense computationally. The accuracy of the proposed method was demonstrated in MD calculations of entropies for EAM potential for iron and for MEAM potential for beryllium. The bcc-hcp equilibrium curves for iron calculated for the EAM potential by the thermodynamic integration method and by the proposed one agree quite well.

  12. Multiple topological phases in phononic crystals

    KAUST Repository

    Chen, Zeguo


    We report a new topological phononic crystal in a ring-waveguide acoustic system. In the previous reports on topological phononic crystals, there are two types of topological phases: quantum Hall phase and quantum spin Hall phase. A key point in achieving quantum Hall insulator is to break the time-reversal (TR) symmetry, and for quantum spin Hall insulator, the construction of pseudo-spin is necessary. We build such pseudo-spin states under particular crystalline symmetry (C-6v) and then break the degeneracy of the pseudo-spin states by introducing airflow to the ring. We study the topology evolution by changing both the geometric parameters of the unit cell and the strength of the applied airflow. We find that the system exhibits three phases: quantum spin Hall phase, conventional insulator phase and a new quantum anomalous Hall phase.

  13. Allantoin as a solid phase adsorbent for removing endotoxins. (United States)

    Vagenende, Vincent; Ching, Tim-Jang; Chua, Rui-Jing; Gagnon, Pete


    In this study we present a simple and robust method for removing endotoxins from protein solutions by using crystals of the small-molecule compound 2,5-dioxo-4-imidazolidinyl urea (allantoin) as a solid phase adsorbent. Allantoin crystalline powder is added to a protein solution at supersaturated concentrations, endotoxins bind and undissolved allantoin crystals with bound endotoxins are removed by filtration or centrifugation. This method removes an average of 99.98% endotoxin for 20 test proteins. The average protein recovery is ∼80%. Endotoxin binding is largely independent of pH, conductivity, reducing agent and various organic solvents. This is consistent with a hydrogen-bond based binding mechanism. Allantoin does not affect protein activity and stability, and the use of allantoin as a solid phase adsorbent provides better endotoxin removal than anion exchange, polymixin affinity and biological affinity methods for endotoxin clearance. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films grown on glass substrates by solid phase crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Shoichiro [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Kamisaka, Hideyuki [Department of Chemistry, The University of Tokyo (Japan); Hirose, Yasushi; Hasegawa, Tetsuya [Kanagawa Academy of Science and Technology (KAST), Kawasaki (Japan); Department of Chemistry, The University of Tokyo (Japan)


    We investigated the structural, electrical, and optical properties of polycrystalline NbO{sub 2} thin films on glass substrates. The NbO{sub 2} films were crystallized from amorphous precursor films grown by pulsed laser deposition at various oxygen partial pressures (P{sub O2}). The electrical and optical properties of the precursor films systematically changed with P{sub O2}, demonstrating that the oxygen content of the precursor films can be finely controlled with P{sub O2}. The precursors were crystallized into polycrystalline NbO{sub 2} films by annealing under vacuum at 600 C. The NbO{sub 2} films possessed extremely flat surfaces with branching patterns. Even optimized films showed a low resistivity (ρ) of 2 x 10{sup 2} Ω cm, which is much lower than the bulk value of 1 x 10{sup 4} Ω cm, probably because of the inferior crystallinity of the films compared with that of a bulk NbO{sub 2} crystal. Both oxygen-rich and -poor NbO{sub 2} films showed lower ρ than that of the stoichiometric film. The NbO{sub 2} film with the highest ρ showed an indirect bandgap of 0.7 eV. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Pulsed zero field NMR of solids and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Thayer, A.M.


    This work describes the development and applications to solids and liquid crystals of zero field nuclear magnetic resonance (NMR) experiments with pulsed dc magnetic fields. Zero field NMR experiments are one approach for obtaining high resolution spectra of amorphous and polycrystalline materials which normally (in high field) display broad featureless spectra. The behavior of the spin system can be coherently manipulated and probed in zero field with dc magnetic field pulses which are employed in a similar manner to radiofrequency pulses in high field NMR experiments. Nematic phases of liquid crystalline systems are studied in order to observe the effects of the removal of an applied magnetic field on sample alignment and molecular order parameters. In nematic phases with positive and negative magnetic susceptibility anisotropies, a comparison between the forms of the spin interactions in high and low fields is made. High resolution zero field NMR spectra of unaligned smectic samples are also obtained and reflect the symmetry of the liquid crystalline environment. These experiments are a sensitive measure of the motionally induced asymmetry in biaxial phases. Homonuclear and heteronuclear solute spin systems are compared in the nematic and smectic phases. Nonaxially symmetric dipolar couplings are reported for several systems. The effects of residual fields in the presence of a non-zero asymmetry parameter are discussed theoretically and presented experimentally. Computer programs for simulations of these and other experimental results are also reported. 179 refs., 75 figs.

  16. Phase change material for efficient removal of crystal violet dye. (United States)

    Haik, Yousef; Qadri, Shahnaz; Ganoe, Ashley; Ashraf, Sarmadia; Sawafta, Reyad


    Hazardous dye removal and recovery from wastewater requires efficient capturing material. We report a phase change material (PCM) with phase change temperature of 16 degrees C giving up to 98% removal of crystal violet in few minutes. The PCM was found to collect 54 times of its weight soluble dye. The dye adsorption kinetics obeys a second order pseudo rate. Upon cooling the PCM to below 16 degrees C it gels and enabled solid removal of the captured dye. 2009 Elsevier B.V. All rights reserved.

  17. Phase-field-crystal model for ordered crystals. (United States)

    Alster, Eli; Elder, K R; Hoyt, Jeffrey J; Voorhees, Peter W


    We describe a general method to model multicomponent ordered crystals using the phase-field-crystal (PFC) formalism. As a test case, a generic B2 compound is investigated. We are able to produce a line of either first-order or second-order order-disorder phase transitions, features that have not been incorporated in existing PFC approaches. Further, it is found that the only elastic constant for B2 that depends on ordering is C_{11}. This B2 model is then used to study antiphase boundaries (APBs). The APBs are shown to reproduce classical mean-field results. Dynamical simulations of ordering across small-angle grain boundaries predict that dislocation cores pin the evolution of APBs.

  18. Growth of single crystals of BaFe12O19 by solid state crystal growth (United States)

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


    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.

  19. Solid phase sequencing of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Cantor, Charles R.; Hubert, Koster


    This invention relates to methods for detecting and sequencing target nucleic acid sequences, to mass modified nucleic acid probes and arrays of probes useful in these methods, and to kits and systems which contain these probes. Useful methods involve hybridizing the nucleic acids or nucleic acids which represent complementary or homologous sequences of the target to an array of nucleic acid probes. These probes comprise a single-stranded portion, an optional double-stranded portion and a variable sequence within the single-stranded portion. The molecular weights of the hybridized nucleic acids of the set can be determined by mass spectroscopy, and the sequence of the target determined from the molecular weights of the fragments. Probes may be affixed to a solid support such as a hybridization chip to facilitate automated molecular weight analysis and identification of the target sequence.

  20. Solid phase sequencing of biopolymers

    Energy Technology Data Exchange (ETDEWEB)

    Cantor, Charles (Del Mar, CA); Koster, Hubert (La Jolla, CA)


    This invention relates to methods for detecting and sequencing target nucleic acid sequences, to mass modified nucleic acid probes and arrays of probes useful in these methods, and to kits and systems which contain these probes. Useful methods involve hybridizing the nucleic acids or nucleic acids which represent complementary or homologous sequences of the target to an array of nucleic acid probes. These probes comprise a single-stranded portion, an optional double-stranded portion and a variable sequence within the single-stranded portion. The molecular weights of the hybridized nucleic acids of the set can be determined by mass spectroscopy, and the sequence of the target determined from the molecular weights of the fragments. Nucleic acids whose sequences can be determined include DNA or RNA in biological samples such as patient biopsies and environmental samples. Probes may be fixed to a solid support such as a hybridization chip to facilitate automated molecular weight analysis and identification of the target sequence.

  1. Measurements of solids concentration and axial solids velocity in gas-solid two-phase flows.

    NARCIS (Netherlands)

    Nieuwland, J.J.; Nieuwland, J.J.; Meijer, R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria


    Several techniques reported in the literature for measuring solids concentration and solids velocity in (dense) gas-solid two-phase flow have been briefly reviewed. An optical measuring system, based on detection of light reflected by the suspended particles, has been developed to measure local

  2. Lyotropic Liquid Crystal Phases from Anisotropic Nanomaterials

    Directory of Open Access Journals (Sweden)

    Ingo Dierking


    Full Text Available Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii novel functionalities can be added to the liquid crystal; and (iii the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.

  3. Bending crystals. Solid state photomechanical properties of ...

    Indian Academy of Sciences (India)


    Prior to the early 1970's there were many reports on transition metal complexes formed with catecholate ligands ... incident light source is switched on, the crystal bends and the laser beam is deflected on the screen. .... The reaction carried out by first treating Co2(CO)8 with 3,6-di-tert-butyl-1,2-benzo- quinone, followed by ...

  4. Electrically tunable bandpass filter using solid-core photonic crystal fibers filled with multiple liquid crystals

    DEFF Research Database (Denmark)

    Wei, Lei; Alkeskjold, Thomas Tanggaard; Bjarklev, Anders Overgaard


    An electrically tunable bandpass filter is designed and fabricated by integrating two solid-core photonic crystal fibers filled with different liquid crystals in a double silicon v-groove assembly. By separately controlling the driving voltage of each liquid-crystal-filled section, both the short......-wavelength edge and the long-wavelength edge of the bandpass filter are tuned individually or simultaneously with the response time in the millisecond range....

  5. Smectic phases in ionic liquid crystals. (United States)

    Bartsch, Hendrik; Bier, Markus; Dietrich, S


    Ionic liquid crystals (ILCs) are anisotropic mesogenic molecules which carry charges and therefore combine properties of liquid crystals, e.g. the formation of mesophases, and of ionic liquids, such as low melting temperatures and tiny triple-point pressures. Previous density functional calculations have revealed that the phase behavior of ILCs is strongly affected by their molecular properties, i.e. their aspect ratio, the loci of the charges, and their interaction strengths. Here, we report new findings concerning the phase behavior of ILCs as obtained by density functional theory and Monte Carlo simulations. The most important result is the occurrence of a novel, wide smectic-A phase [Formula: see text], at low temperature, the layer spacing of which is larger than that of the ordinary high-temperature smectic-A phase [Formula: see text]. Unlike the ordinary smectic S A phase, the structure of the [Formula: see text] phase consists of alternating layers of particles oriented parallel to the layer normal and oriented perpendicular to it.

  6. Immuno-affinity solid-phase extraction. (United States)

    Stevenson, D


    The measurement of trace organics such as drugs and pesticides at low concentration in biological and environmental samples is a challenging analytical task. Despite recent advances in instrumentation most analysts regard sample preparation as the rate-limiting step in the overall analytical method. In recent years there has been a lot of interest in immobilising antibodies onto solid supports such as silica to provide highly selective solid-phase extraction. This paper reviews the use of immuno-affinity for solid-phase extraction. It uses as examples extraction of chlortoluron and isoproturon from water and morphine and clenbuterol in urine and plasma respectively. An extensive list of other examples is given. Optimisation procedures are discussed in detail.

  7. Multiplexed Colorimetric Solid-Phase Extraction (United States)

    Gazda, Daniel B.; Fritz, James S.; Porter, Marc D.


    Multiplexed colorimetric solid-phase extraction (MC-SPE) is an extension of colorimetric solid-phase extraction (C-SPE) an analytical platform that combines colorimetric reagents, solid phase extraction, and diffuse reflectance spectroscopy to quantify trace analytes in water. In CSPE, analytes are extracted and complexed on the surface of an extraction membrane impregnated with a colorimetric reagent. The analytes are then quantified directly on the membrane surface using a handheld diffuse reflectance spectrophotometer. Importantly, the use of solid-phase extraction membranes as the matrix for impregnation of the colorimetric reagents creates a concentration factor that enables the detection of low concentrations of analytes in small sample volumes. In extending C-SPE to a multiplexed format, a filter holder that incorporates discrete analysis channels and a jig that facilitates the concurrent operation of multiple sample syringes have been designed, enabling the simultaneous determination of multiple analytes. Separate, single analyte membranes, placed in a readout cartridge create unique, analyte-specific addresses at the exit of each channel. Following sample exposure, the diffuse reflectance spectrum of each address is collected serially and the Kubelka-Munk function is used to quantify each water quality parameter via calibration curves. In a demonstration, MC-SPE was used to measure the pH of a sample and quantitate Ag(I) and Ni(II).

  8. Phase-field-crystal model for fcc ordering (United States)

    Wu, Kuo-An; Adland, Ari; Karma, Alain


    We develop and analyze a two-mode phase-field-crystal model to describe fcc ordering. The model is formulated by coupling two different sets of crystal density waves corresponding to ⟨111⟩ and ⟨200⟩ reciprocal lattice vectors, which are chosen to form triads so as to produce a simple free-energy landscape with coexistence of crystal and liquid phases. The feasibility of the approach is demonstrated with numerical examples of polycrystalline and (111) twin growth. We use a two-mode amplitude expansion to characterize analytically the free-energy landscape of the model, identifying parameter ranges where fcc is stable or metastable with respect to bcc. In addition, we derive analytical expressions for the elastic constants for both fcc and bcc. Those expressions show that a nonvanishing amplitude of [200] density waves is essential to obtain mechanically stable fcc crystals with a nonvanishing tetragonal shear modulus (C11-C12)/2 . We determine the model parameters for specific materials by fitting the peak liquid structure factor properties and solid-density wave amplitudes following the approach developed for bcc [K.-A. Wu and A. Karma, Phys. Rev. B 76, 184107 (2007)]. This procedure yields reasonable predictions of elastic constants for both bcc Fe and fcc Ni using input parameters from molecular dynamics simulations. The application of the model to two-dimensional square lattices is also briefly examined.

  9. Thermodynamically controlled crystallization of glucose pentaacetates from amorphous phase

    Energy Technology Data Exchange (ETDEWEB)

    Wlodarczyk, P., E-mail:; Hawelek, L.; Hudecki, A.; Kolano-Burian, A. [Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice (Poland); Wlodarczyk, A. [Department of Animal Histology and Embryology, University of Silesia, ul. Bankowa 9, 40-007 Katowice (Poland)


    The α and β glucose pentaacetates are known sugar derivatives, which can be potentially used as stabilizers of amorphous phase of active ingredients of drugs (API). In the present work, crystallization behavior of equimolar mixture of α and β form in comparison to both pure anomers is revealed. It was shown that despite the same molecular interactions and similar molecular dynamics, crystallization from amorphous phase is significantly suppressed in equimolar mixture. Time dependent X-ray diffraction studies confirmed higher stability of the quenched amorphous equimolar mixture. Its tendency to crystallization is about 10 times lower than for pure anomers. Calorimetric studies revealed that the α and β anomers don’t form solid solutions and have eutectic point for x{sub α} = 0.625. Suppressed crystallization tendency in the mixture is probably caused by the altered thermodynamics of the system. The factors such as difference of free energy between crystalline and amorphous state or altered configurational entropy are probably responsible for the inhibitory effect.

  10. Crystal Phase Quantum Well Emission with Digital Control. (United States)

    Assali, S; Lähnemann, J; Vu, T T T; Jöns, K D; Gagliano, L; Verheijen, M A; Akopian, N; Bakkers, E P A M; Haverkort, J E M


    One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc-blende (ZB) and wurtzite (WZ) phases. Such a crystal phase switching results in the formation of crystal phase quantum wells (CPQWs) and quantum dots (CPQDs). For GaP CPQWs, the inherent electric fields due to the discontinuity of the spontaneous polarization at the WZ/ZB junctions lead to the confinement of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier. The energy spacing between the sharp emission lines is uniform and is defined by the addition of single ZB monolayers. The controlled growth of identical quantum wells with atomically flat interfaces at predefined positions featuring digitally tunable discrete emission energies may provide a new route to further advance entangled photons in solid state quantum systems.

  11. Unveiling Hidden Phases of Solid 4He (United States)

    Choi, H.; Kwon, S.; Kim, D. Y.; Kim, E.


    The discovery of non-classical rotational inertia fraction (NCRIF) of solid 4He in a torsional oscillator (TO) was immediately followed by various attempts to identify the underlying physics of the phenomenon. Despite the efforts the true nature of the non-classical response is still not fully understood. We have investigated dynamic response of solid 4He by changing oscillation rim velocity at fixed temperatures. Main discovery of our experiment is that there are hidden phases of solid 4He that are only accessible by cooling the sample down to some temperature with zero to small rim velocity first, and then subsequently raising the velocity at that temperature. The different phases are identified with two distinct features. One is that the amount of NCRIF is different from that of a typical high-velocity cooled 4He. The other is that the dynamics of the TO changes across these different phases. We believe these phases are distinguished by different pinning mechanisms of excitations present in 4He.

  12. Crystal habit prediction - Including the liquid as well as the solid side

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, C.; Ulrich, J. [Martin-Luther-Universitaet Halle-Wittenberg, Zentrum fuer Ingenieurwissenschaften, Verfahrenstechnik/ TVT, 06099 Halle (Saale) (Germany)


    Commercially available methods of morphology prediction utilize molecular dynamics to estimate the crystal growth rates but predominantly consider the solid side. For the extension of these methods to a multi-component solid-liquid system the diffusion coefficient is required. Since, the diffusion coefficient enables the calculation of crystal growth rates and the morphology in presence of additives and solvents. Modeling the diffusion coefficient is achieved by conducting MD on a system consisting of the crystal surface and the liquid phase. The achieved results match very well with the calculated diffusion coefficient (Wilke-Chang). In this case study benzoic acid is used as model substance with water as solvent. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Size Dependence of a Temperature-Induced Solid-Solid Phase Transition in Copper(I) Sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Rivest, Jessy B; Fong, Lam-Kiu; Jain, Prashant K; Toney, Michael F; Alivisatos, A Paul


    Determination of the phase diagrams for the nanocrystalline forms of materials is crucial for our understanding of nanostructures and the design of functional materials using nanoscale building blocks. The ability to study such transformations in nanomaterials with controlled shape offers further insight into transition mechanisms and the influence of particular facets. Here we present an investigation of the size-dependent, temperature-induced solid-solid phase transition in copper sulfide nanorods from low- to high-chalcocite. We find the transition temperature to be substantially reduced, with the high chalcocite phase appearing in the smallest nanocrystals at temperatures so low that they are typical of photovoltaic operation. Size dependence in phase trans- formations suggests the possibility of accessing morphologies that are not found in bulk solids at ambient conditions. These other- wise-inaccessible crystal phases could enable higher-performing materials in a range of applications, including sensing, switching, lighting, and photovoltaics.

  14. Wax Precipitation Modeled with Many Mixed Solid Phases

    DEFF Research Database (Denmark)

    Heidemann, Robert A.; Madsen, Jesper; Stenby, Erling Halfdan


    The behavior of the Coutinho UNIQUAC model for solid wax phases has been examined. The model can produce as many mixed solid phases as the number of waxy components. In binary mixtures, the solid rich in the lighter component contains little of the heavier component but the second phase shows...... substantial amounts of the lighter component dissolved in the heavier solid. Calculations have been performed taking into account the recrystallization of the solid alkanes into a second solid form. The Coutinho UNIQUAC model has been used to describe the lower-temperature solid phases. The higher......-temperature mixed solid phase has been assumed to be either an ideal solution or to be described by Coutinho's Wilson activity coefficient model. This procedure accounts for more of the known behavior of mixed n-alkane solids. Comparison is also made with results assuming that all of the solid phases, both high...

  15. New Monte Carlo method to compute the free energy of arbitrary solid phases. Application to the FCC and HCP phases of hard spheres

    NARCIS (Netherlands)

    Frenkel, D.; Ladd, A.J.C.


    We present a new method to compute the absolute free energy of arbitrary solid phases by Monte Carlo simulation. The method is based on the construction of a reversible path from the solid phase under consideration to an Einstein crystal with the same crystallographic structure. As an application of

  16. Temperature independent low voltage polymer stabilized blue phase liquid crystals (United States)

    Kemiklioglu, E.; Hwang, J. Y.; Chien, L.-C.


    Blue phases are types of liquid crystal phase which can appear in a narrow temperature range between a chiral nematic phase and isotropic liquid phase. Blue Phase (BP) liquid crystals have been known to exist in a small temperature range. Recently, broadening the temperature range of a BP liquid crystal has occurred by using a mixture of nematic bimesogenic liquid crystals or by polymerizing a small amount of monomer in a BP to stabilize the cubic lattice against temperature variation. In this study, we report a low switching voltage polymer stabilized blue phase (PSBP) liquid crystal device. We showed the stabilization of blue phases over a temperature range of 30.4 °C including room temperature. We observed the temperature independent of Bragg wavelength. Furthermore, the polymer effect on the electo-optic properties of a self assembled nanostructured blue phase liquid crystal composites have been investigated. As well as the ratio between two monomers, the overall monomers concentration is controlled.

  17. Solid-phase sequencing on the gas-phase sequencer. (United States)

    Sarin, V K; Kim, Y; Fox, J L


    Automated Edman degradation has been successfully used for determining the primary structure of numerous peptides and proteins. Quantitative solid-phase Edman degradation has great potential use for amino acid sequence analysis of synthetic peptides assembled on resin support by the Merrifield procedure. We report here the combined use of a modified gas-phase sequencer program and our improved reversed-phase HPLC analysis for PTH-amino acids to carry out the sequence analysis on synthesized peptide resins. This approach is far more sensitive than using glass beads on the conventional solid-phase sequencer. The peptide was assembled on copoly (styrene-1% divinylbenzene) resin beads at an initial substitution of 0.54 mmol/g. On a routine basis, 10-15 resin beads are used, and a repetitive yield of 94% is obtained: as few as 4 beads can be successfully sequenced. The HPLC PTH-amino acid analysis is sensitive down to subpicomole quantities. This procedure offers a sensitive and rapid analytical tool for checking the purity of peptides as they are being assembled on solid support.

  18. Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy. (United States)

    Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon


    We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

  19. Holographic polymer-dispersed liquid crystal Bragg grating integrated inside a solid core photonic crystal fiber


    Zito, Gianluigi; Pissadakis, Stavros


    A polymer/liquid crystal-based fiber Bragg grating (PLC-FBG) is fabricated with visible two-beam holography by photo-induced modulation of a pre-polymer/LC solution infiltrated into the hollow channels of a solid core photonic crystal fiber (PCF). The fabrication process and effects related to the photonic bandgap guidance into the infiltrated PCF, and characterization of the PLC-FBG are discussed. Experimental data here presented, demonstrate that the liquid crystal inclusions of the PLC-FBG...

  20. Quantum Chemistry of Solids LCAO Treatment of Crystals and Nanostructures

    CERN Document Server

    Evarestov, Robert A


    Quantum Chemistry of Solids delivers a comprehensive account of the main features and possibilities of LCAO methods for the first principles calculations of electronic structure of periodic systems. The first part describes the basic theory underlying the LCAO methods  applied to periodic systems and the use of Hartree-Fock(HF), Density Function theory(DFT) and hybrid Hamiltonians. The translation and site symmetry consideration is included to establish connection between k-space solid –state physics and real-space quantum chemistry. The inclusion of electron correlation effects for periodic systems is considered on the basis of localized crystalline orbitals. The possibilities of LCAO methods for chemical bonding analysis in periodic systems are discussed. The second part deals with the applications of LCAO methods  for calculations of bulk crystal properties, including magnetic ordering and crystal structure optimization.  In the second edition two new chapters are added in the application part II of t...

  1. Quantum Liquid Crystal Phases in Strongly Correlated Fermionic Systems (United States)

    Sun, Kai


    This thesis is devoted to the investigation of the quantum liquid crystal phases in strongly correlated electronic systems. Such phases are characterized by their partially broken spatial symmetries and are observed in various strongly correlated systems as being summarized in Chapter 1. Although quantum liquid crystal phases often involve…

  2. Phase field crystal modeling of ternary solidification microstructures


    Berghoff, Marco; Nestler, Britta


    In the present work, we present a free energy derivation of the multi-component phase-field crystal model [1] and illustrate the capability to simulate dendritic and eutectic solidification in ternary alloys. Fast free energy minimization by a simulated annealing algorithm of an approximated crystal is compared with the free energy of a fully simulated phase field crystal structure. The calculation of ternary phase diagrams from these free energies is described. Based on the free energies rel...

  3. Influence Cr on Crystallization and the Phase Transformations of the Bronze BA1044

    Directory of Open Access Journals (Sweden)

    B. P. Pisarek


    Full Text Available The investigations were introduced in the paper, method of thermal and derivative analysis (TDA, the process of crystallization and phase transformation in the solid state of the aluminium bronze CuA110Fe4Ni4 (BA1044 and with the addition 0.3% Cr. Two intermetallic phase were identified in the microstructure of the bronze BA1044: κFel - rich in Fe and Cu and κFe2 - rich in Fe, and in the microstructure of the bronze BA1044+0.3 % Cr only one phase κFel - rich in Fe, Cu and Cr. The presence of chrome in the bronze BA1044 reduce size the primary crystals of the phase β, reduces the dynamics of the processes of thermal phase transformation in the solid state and lengthens the time their of duration.

  4. Development of new tags for solid-phase peptide synthesis


    Knecht, Steven


    the synthesis of polypeptides. In 1984, he was awarded with the Nobel Prize “for his development of methodology for chemical synthesis on a solid matrix”. Compared to solution-phase methods, solid-phase chemistry offers many advantages in terms of efficiency as well as purification procedures. Particularly for longer peptide sequences, in solution-phase chemistry the isolation of all peptide intermediates is required, whereas in a solid-phase approach simple wash and filter procedures enable ...

  5. Phase Change Enthalpies and Entropies of Liquid Crystals

    National Research Council Canada - National Science Library

    Acree, William E; Chickos, James S


    .... A group additivity approach used to estimate total phase change entropies of organic molecules applied to 627 of these liquid crystals is found to significantly overestimate their total phase change entropies...

  6. Photon Cascade from a Single Crystal Phase Nanowire Quantum Dot

    DEFF Research Database (Denmark)

    Bouwes Bavinck, Maaike; Jöns, Klaus D; Zieliński, Michal


    We report the first comprehensive experimental and theoretical study of the optical properties of single crystal phase quantum dots in InP nanowires. Crystal phase quantum dots are defined by a transition in the crystallographic lattice between zinc blende and wurtzite segments and therefore offe...

  7. Supramolecular gel phase crystallization: orthogonal self-assembly under non-equilibrium conditions. (United States)

    Kumar, D Krishna; Steed, Jonathan W


    This tutorial review charts the history of gel phase crystallization from its origins in Liesegang ring formation to current research in the generation of new pharmaceutical solid forms in low molecular weight organogels. The growth of molecular crystals under a supersaturation gradient within the same space and timescale as the formation of a gel phase material is placed into context as an example of orthogonal self-assembly. Such multi-component, weakly coupled orthogonal self-assembly processes occurring far from equilibrium represent a powerful conceptual paradigm for generating fascinating emergent behaviour in chemical systems.

  8. Unique Reversible Crystal-to-Crystal Phase Transition – Structural and Functional Properties of Fused Ladder Thienoarenes

    KAUST Repository

    Abe, Yuichiro


    Donor-acceptor type molecules based on fused ladder thienoarenes, indacenodithiophene (IDT) and dithienocyclopenta-thienothiophene (DTCTT), coupled with benzothiadiazole, are prepared and their solid-state structures are investigated. They display a rich variety of solid phases ranging from amorphous glass states to crystalline states, upon changes in the central aromatic core and side group structures. Most notably, the DTCTT-based derivatives showed reversible crystal-to-crystal phase transitions in heating and cooling cycles. Unlike what has been seen in π−conjugated molecules variable temperature XRD revealed that structural change occurs continuously during the transition. A columnar self-assembled structure with slip-stacked π−π interaction is proposed to be involved in the solid-state. This research provides the evidence of unique structural behavior of the DTCTT-based molecules through the detailed structural analysis. This unique structural transition paves the way for these materials to have self-healing of crystal defects, leading to improved optoelectronic properties.

  9. Solid crystal suspensions containing griseofulvin--preparation and bioavailability testing. (United States)

    Reitz, Elena; Vervaet, Chris; Neubert, Reinhard H H; Thommes, Markus


    The improvement of the bioavailability of poorly soluble drugs has been an important issue in pharmaceutical research for many years. Despite the suggestion of several other technologies in the past, drug particle size reduction is still an appropriate strategy to guarantee high bioavailability of various drugs. A few years ago, the Solid Crystal Suspension (SCS) technology was suggested, in which crystalline drug particles are ground and dispersed in a highly soluble crystalline carrier by a hot melt extrusion process. The current study demonstrates the scale-up of the SCS technology to standard, lab-scale extrusion equipment--a change from previous investigations, which used small batch sizes. A twin-screw extruder was modified to account for the rapid crystallization of the carrier. The screw speed and the barrel temperature were identified as critical process parameters and were varied systematically in several experimental designs. Finally, parameters were identified that produced extrudates with rapid dissolution rates. After extrusion, the extrudates were milled to granules and then tableted. These tablets were investigated with respect to their bioavailability in beagle dogs. It was found that drug particle size reduction in the hot melt extrusion led to 3.5-fold higher bioavailability in these dogs than occurred with the physical mixture of the used substances. The solid crystal suspension formulation had a slightly higher bioavailability than the marked product. In conclusion, the SCS technology was successfully scaled up to lab-scale equipment, and the concept was confirmed by a bioavailability study. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Impact of polymers on the crystallization and phase transition kinetics of amorphous nifedipine during dissolution in aqueous media. (United States)

    Raina, Shweta A; Alonzo, David E; Zhang, Geoff G Z; Gao, Yi; Taylor, Lynne S


    The commercial and clinical success of amorphous solid dispersions (ASD) in overcoming the low bioavailability of poorly soluble molecules has generated momentum among pharmaceutical scientists to advance the fundamental understanding of these complex systems. A major limitation of these formulations stems from the propensity of amorphous solids to crystallize upon exposure to aqueous media. This study was specifically focused on developing analytical techniques to evaluate the impact of polymers on the crystallization behavior during dissolution, which is critical in designing effective amorphous formulations. In the study, the crystallization and polymorphic conversions of a model compound, nifedipine, were explored in the absence and presence of polyvinylpyrrolidone (PVP), hydroxypropylmethyl cellulose (HPMC), and HPMC-acetate succinate (HPMC-AS). A combination of analytical approaches including Raman spectroscopy, polarized light microscopy, and chemometric techniques such as multivariate curve resolution (MCR) were used to evaluate the kinetics of crystallization and polymorphic transitions as well as to identify the primary route of crystallization, i.e., whether crystallization took place in the dissolving solid matrix or from the supersaturated solutions generated during dissolution. Pure amorphous nifedipine, when exposed to aqueous media, was found to crystallize rapidly from the amorphous matrix, even when polymers were present in the dissolution medium. Matrix crystallization was avoided when amorphous solid dispersions were prepared, however, crystallization from the solution phase was rapid. MCR was found to be an excellent data processing technique to deconvolute the complex phase transition behavior of nifedipine.

  11. Crystallization of semi-insulating HVPE-GaN with solid iron as a source of dopants (United States)

    Iwinska, M.; Piotrzkowski, R.; Litwin-Staszewska, E.; Ivanov, V. Yu.; Teisseyre, H.; Amilusik, M.; Lucznik, B.; Fijalkowski, M.; Sochacki, T.; Takekawa, N.; Murakami, H.; Bockowski, M.


    Gallium nitride crystals were grown by hydride vapor phase epitaxy using solid iron as a source of dopants. Three crystal growth processes were performed at constant HCl flow over the solid iron and with different gallium chloride flows. High structural quality ammonothermal GaN was used as seed material. No yellow luminescence and only weak near band edge luminescence were visible in all grown crystals. A sharp peak was observed at 1.298 eV. This was shown before as an intrinsic transition of Fe impurity in GaN. The grown crystals were highly resistive at room temperature. High-temperature Hall effect measurements revealed n-type conductivity with activation energy equal to 1.8 eV. Secondary ion mass spectrometry indicated the presence of manganese in all three samples. The concentration of manganese was always higher than concentration of iron in the doped GaN.

  12. Liquid Crystals - The 'Fourth' Phase of Matter

    Indian Academy of Sciences (India)

    most well-known application is the liquid crystal-display (LCD), used in watches, calculators, flat panel displays used recently even in TV sets, and so on. The anisotropic properties of liquid crystals in refractive index and dielectric constant can be exploited for the purposes of creating flat-panel displays. Usually what is done ...

  13. Relationship between crystal structure and solid-state properties of pharmaceuticals (United States)

    Sheth, Agam R.

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

  14. Crystal Properties and Radiation Effects in Solid Molecular Hydrogens

    Energy Technology Data Exchange (ETDEWEB)

    Kozioiziemski, B


    The crystal lattice structure, growth shapes and helium generated by beta-decay of solid deuterium-tritium (D-T) mixtures have been studied. Understanding of these D-T properties is important for predicting and optimizing the target design of the National Ignition Facility (NIF). Raman spectroscopy showed the D-T crystal structure is hexagonal close packed, common to the non-tritiated isotopes. The isotopic mixtures of both tritiated and non-tritiated species broadens the rotational transitions, especially of the lighter species in the mixture. The vibrational frequencies of each isotope is shifted to higher energy in the mixture than the pure components. The J = 1-0 population decreases exponentially with a 1/e time constant which rapidly increases above 10.5 K for both D{sub 2} and T{sub 2} in D-T. The conversion rate is nearly constant from 5 K to 10 K for both D{sub 2} and T{sub 2} at 7.1 hours and 2.1 hours, respectively. The smoothing of D-T layers by beta decay heating is limited by the crystal surface energy. Deuterium and hydrogen-deuteride crystals were grown at a number of temperatures below the triple point to determine the surface energy and roughening transition. Several distinct crystal shapes were observed on a number of different substrates. The a facet roughens between 0.9 T{sub TP} and T{sub TP}, while the c facet persists up to the melting temperature. This is very different from the behavior of the other rare gas crystals which grow completely rounded above 0.8 T{sub TP}. Helium bubbles formed as a product of the beta decay were observed using optical microscopy and the diffusion of smaller bubbles measured with dynamic light scattering. Bubble diffusion coefficients as high as 2.0 x 10{sup -16} m{sup 2}/s were measured for 10-50 nm bubbles. The bubbles move in response to a thermal gradient, with speeds between 1 {micro}m/hour and 100 {micro}m/hour for thermal gradients and temperatures appropriate to NIF targets.

  15. Band structure computation of polygonal solid-solid phononic crystal with features using frequency domain spectral superelement method (United States)

    Mukherjee, Sushovan; Gopalakrishnan, S.


    Phononic crystals are synthetic materials with a periodic structure having spatial variations of elasto-inertial properties of constituent materials, aimed at developing devices and bulk material with engineered acoustic/ elastic properties. Multi-material structures with sides of a space filling polygonal tessellation, can constitute solid-solid phononic crystal. Coupled with inclusions and features, phononic crystals show rich and varied band structure phenomenon. We use frequency domain spectral superelement method and Bloch theory to efficiently calculate the band structures of such phononic crystals. We particularly investigate hexagonal honeycombs to assess the impacts of joint elasticity, inertia and circular and elliptical holes on band gap behavior.

  16. Role of nanoparticles in analytical solid phase microextraction (SPME)

    NARCIS (Netherlands)

    Zielinska, K.; Leeuwen, van H.P.


    Solid phase microextraction (SPME) is commonly used to measure the free concentration of fairly hydrophobic substances in aqueous media on the basis of their partitioning between sample solution and a solid phase. Here we study the role of nanoparticles that may sorb the analyte in the sample

  17. Utilizing liquid crystal phases to obtain highly ordered thin films for organic electronics (United States)

    Springer, Mike T.

    Organic electronic materials offer several advantages when compared to inorganic materials, but they suffer from low charge carrier mobility. Two major factors hindering effective charge transport in organic materials are: 1) effective wavefunction overlap in organic crystals and 2) the domain morphology of thin films. Charge transport in organic materials occurs via a hopping mechanism along the conjugated pi system. Often, rigid, aromatic organic materials crystallize in a herringbone, edge-to-face orientation, limiting pi-pi stacking and decreasing charge carrier mobility. Face-to-face orientation of aromatic rings decreases intermolecular pi-pi distances and increases wavefunction overlap. Control of the crystal structure can be achieved to some extent by tuning structural features of the molecule, like increasing the ratio of carbon atoms to hydrogen atoms in the aromatic rings; this is often achieved by introducing heteroatoms like sulfur and oxygen into the aromatic ring structure. Thin films of organic materials often contain many unaligned domains; this is caused by rapid crystallization. Control of the domain morphology of thin films has been shown to increase charge carrier mobility by 6 orders of magnitude for thin films of the same material. Liquid crystal phases allow a slow process of crystallization, whereby the molecules in a thin film can be slowly aligned into a monodomain before crystallization. The crystal-smectic phases, like smectic E, are particularly attractive for this strategy due to their high degree of intermolecular order. This project describes the synthesis and characterization of organic semiconductors designed to exhibit short pi-pi distances and highly ordered crystal-smectic phases to obtain thin films with high charge carrier mobility. The n,2-OBTTT series contains 15 newly designed and synthesized mesogens. The liquid crystal and solid crystal structures of these mesogens are examined and deposition conditions are optimized for

  18. Isothermal microcalorimetry to investigate the phase separation for amorphous solid dispersions of AMG 517 with HPMC-AS. (United States)

    Calahan, Julie L; Zanon, Roger L; Alvarez-Nunez, Fernando; Munson, Eric J


    Understanding the crystallization kinetics of an amorphous drug is critical for the development of an amorphous solid dispersion (ASD) formulation. This paper examines the phase separation and crystallization of the drug AMG 517 in ASDs of varying drug load at various conditions of temperature and relative humidity using isothermal microcalorimetry. ASDs of AMG 517 in hydroxypropyl methylcellulose acetate succinate (HPMC-AS) were manufactured using a Buchi 290 mini spray dryer system. ASDs were characterized using modulated differential scanning calorimetry (mDSC) and scanning electron microscopy (SEM) prior to isothermal microcalorimetry evaluation, and crystallinity was measured using (19)F solid state nuclear magnetic resonance spectroscopy (SSNMR), before and after crystallization. The crystallization of ASDs of AMG 517 in HPMC-AS was significantly slowed by the presence of HPMC-AS polymer, indicating enhanced physical stability for the ASD formulations. A two-phase crystallization was observed by isothermal microcalorimetry at temperatures near the glass transition temperature (Tg), indicating a drug-rich phase and a miscible ASD phase. (19)F SSNMR showed that only partial crystallization of the drug occurred for the ASDs, suggesting a third phase which did not crystallize, possibly representing a thermodynamically stable, soluble component. Isothermal microcalorimetry provides important kinetic data for monitoring crystallization of the drug in the ASDs and, together with (19)F SSNMR, suggests a three-phase ASD system for AMG 517 in HPMC-AS.

  19. Crystallization kinetics of the phase change material GeSb6Te measured with dynamic transmission electron microscopy. (United States)

    Winseck, M M; Cheng, H-Y; Campbell, G H; Santala, M K


    GeSb6Te is a chalcogenide-based phase change material that has shown great ptoential for use in solid-state memory devices. The crystallization kinetics of amorphous thin films of GeSb6Te during laser crystallization were followed with dynamic transmission electron microscopy, a photo-emission electron microscopy technique with nanosecond-scale time resolution. Nine-frame movies of crystal growth were taken during laser crystallization. The nucleation rate is observed to be very low and the growth rates are very high, up to 10.8 m s(-1) for amorphous as-deposited films and significantly higher for an amorphous film subject to sub-threshold laser annealing before crystallization. The measured growth rates exceed any directly measured growth rate of a phase change material. The crystallization is reminiscent of explosive crystallization of elemental semiconductors both in the magnitude of the growth rate and in the resulting crystalline microstructures.

  20. Supersaturation and crystallization: non-equilibrium dynamics of amorphous solid dispersions for oral drug delivery. (United States)

    Kawakami, Kohsaku


    Amorphous solid dispersions (ASDs) are one of the key formulation technologies that aid the development of poorly soluble candidates. However, their dynamic behaviors, including dissolution and crystallization processes, are still full of mystery. Further understanding of these processes should enhance their wider use. Areas covered: The first part of this review describes the current understanding of the dissolution of ASDs, where phase separation behavior is frequently involved and attempts to develop appropriate dissolution tests to achieve an in vitro-in vivo correlation are examined. The second part of this review discusses crystallization of the drug molecule with the eventual aim of establishing an accelerated testing protocol for predicting its physical stability. Expert opinion: The phase separation behavior from the supersaturated state during the dissolution test must be understood, and its relevance to the oral absorption behavior needs to be clarified. Research efforts should focus on the differences between the phase behavior in in vitro and in vivo situations. Initiation time of the crystallization was shown to be predicted only from storage and glass transition temperatures. This finding should encourage the establishment of testing protocol of the physical stability of ASDs.

  1. An all-solid-state electrochemical double-layer capacitor based on a plastic crystal electrolyte

    Directory of Open Access Journals (Sweden)

    Ali eaabouimrane


    Full Text Available A plastic crystal, solid electrolyte was prepared by mixing tetrabutylammonium hexafluorophosphate salt, (C4H94NPF6, (10 molar % with succinonitrile, SCN, (N C−CH2−CH2−C N, [SCN-10%TBA-PF6]. The resultant waxy material shows a plastic crystalline phase that extend from -36 °C up to its melting at 23 °C. It shows a high ionic conductivity reaching 4 × 10−5 S/cm in the plastic crystal phase (15 °C and ~ 3 × 10−3 S/cm in the molten state (25 °C. These properties along with the high electrochemical stability rendered the use of this material as an electrolyte in an electrochemical double-layer capacitor (EDLC. The EDLC was assembled and its performance was tested by cyclic voltammetry, AC impedance spectroscopy and galvanostatic charge-discharge methods. Specific capacitance values in the range of 4-7 F/g. (of electrode active material were obtained in the plastic crystal phase at 15 °C, that although compare well with those reported for some polymer electrolytes, can be still enhanced with further development of the device and its components, and only demonstrate their great potential use for capacitors as a new application.

  2. Geometric constraints on phase coexistence in vanadium dioxide single crystals. (United States)

    McGahan, Christina; Gamage, Sampath; Liang, Jiran; Cross, Brendan; Marvel, Robert E; Haglund, Richard F; Abate, Yohannes


    The appearance of stripe phases is a characteristic signature of strongly correlated quantum materials, and its origin in phase-changing materials has only recently been recognized as the result of the delicate balance between atomic and mesoscopic materials properties. A vanadium dioxide (VO2) single crystal is one such strongly correlated material with stripe phases. Infrared nano-imaging on low-aspect-ratio, single-crystal VO2 microbeams decorated with resonant plasmonic nanoantennas reveals a novel herringbone pattern of coexisting metallic and insulating domains intercepted and altered by ferroelastic domains, unlike previous reports on high-aspect-ratio VO2 crystals where the coexisting metal/insulator domains appear as alternating stripe phases perpendicular to the growth axis. The metallic domains nucleate below the crystal surface and grow towards the surface with increasing temperature as suggested by the near-field plasmonic response of the gold nanorod antennas.

  3. Liquid crystal phase behaviour of colloidal platelets in external fields

    NARCIS (Netherlands)

    Beek, David van der


    In this thesis, the liquid crystal phase behaviour of colloidal platelets in external fields is studied. We have specifically investigated the influence of morphological, gravitational, magnetic and centrifugal fields. Part I of this thesis involves sterically stabilised colloidal gibbsite

  4. Solid-state three-step model for high-harmonic generation from periodic crystals

    CERN Document Server

    Ikemachi, Takuya; Sato, Takeshi; Yumoto, Junji; Kuwata-Gonokami, Makoto; Ishikawa, Kenichi L


    We study high-harmonic generation (HHG) from solids driven by intense laser pulses using the time-dependent Schrodinger equation for a one-dimensional model periodic crystal. Based on the simulation results, we propose a simple model that can quantitatively explain many aspects of solid- state HHG, some of which have been experimentally observed. Incorporating interband tunneling, intraband acceleration, and recombination with the valence-band hole, our model can be viewed as a solid-state counterpart of the familiar three-step model highly successful for gas-phase HHG and provides a unified basis to understand HHG from gaseous media and solid-state materials. The solid-state three-step model describes how, by repeating intraband acceleration and interband tunneling, electrons climb up across multiple conduction bands. The key parameter in predicting the HHG spectrum structure from the band-climbing process is the peak-to-valley (or valley-to-peak) full amplitude of the pulse vector potential $A(t)$. When the...

  5. Simulating complex crystal structures using the phase-field crystal model (United States)

    Alster, Eli; Montiel, David; Thornton, Katsuyo; Voorhees, Peter W.


    We introduce a phase-field crystal model that creates an array of complex three- and two-dimensional crystal structures via a numerically tractable three-point correlation function. The three-point correlation function is designed in order to energetically favor the principal interplanar angles of a target crystal structure. This is achieved via an analysis performed by examining the crystal's structure factor. This approach successfully yields energetically stable simple cubic, diamond cubic, simple hexagonal, graphene layers, and CaF2 crystals. To illustrate the ability of the method to yield a particularly complex and technologically important crystal structure, we show how this three-point correlation function method can be used to generate perovskite crystals.

  6. Development of n- and p-type Doped Perovskite Single Crystals Using Solid-State Single Crystal Growth (SSCG) Technique (United States)


    develop a new single crystal growth method which is suitable to grow chemically uniform and large “n- and p-type doped” perovskite single crystals...boundary are also fabricated using diffusion bonding process of two single crystal plates. These results demonstrate that the SSCG (solid-state...that can be used to develop new non-linear dielectrics for high-voltage and high-power applications. A major need is to better understand their

  7. Phase-field crystal study of grain-boundary premelting (United States)

    Mellenthin, Jesper; Karma, Alain; Plapp, Mathis


    We study the phenomenon of grain-boundary premelting for temperatures below the melting point in the phase-field crystal model of a pure material with hexagonal ordering in two dimensions. We investigate the structures of symmetric tilt boundaries as a function of misorientation θ for two different inclinations and compute in the grand canonical ensemble the “disjoining potential” V(w) that describes the fundamental interaction between crystal-melt interfaces as a function of the premelted layer width w , which is defined here in terms of the excess mass of the grain boundary via a Gibbs construction. The results reveal qualitatively different behaviors for high-angle grain boundaries that are uniformly wetted, with w diverging logarithmically as the melting point is approached from below, and low-angle boundaries that are punctuated by liquid pools surrounding dislocations, separated by solid bridges. The latter persist over a superheated range of temperature. This qualitative difference between high- and low-angle boundaries is reflected in the w dependence of the disjoining potential that is purely repulsive [ V'(w)<0 for all w ] for misorientations larger than a critical angle θc , but switches from repulsive at small w to attractive at large w for θ<θc . In the latter case, V(w) has a minimum that corresponds to a premelted boundary of finite width at the melting point. Furthermore, we find that the standard wetting condition γgb(θc)=2γsl gives a much too low estimate of θc when a low-temperature value of the grain-boundary energy γgb is used. In contrast, a reasonable lower-bound estimate can be obtained if γgb is extrapolated to the melting point, taking into account both the elastic softening of the material at high homologous temperature and local melting around dislocations.

  8. Effect of transition dipole phase on high-order-harmonic generation in solid materials (United States)

    Jiang, Shicheng; Wei, Hui; Chen, Jigen; Yu, Chao; Lu, Ruifeng; Lin, C. D.


    High-order harmonic spectra from solid materials driven by single-color multicycle laser fields sometimes contain even harmonics. In this work we attribute the appearance of even harmonics to the nonzero transition dipole phase (TDP) when the solid system has broken symmetry. By calculating the harmonic efficiency from graphene and gapped graphene by using the semiconductor Bloch equations under the tight-binding approximation, we demonstrate the role of the TDP, which has been ignored for a long time. When the crystal has inversion symmetry, or reflection symmetry with the symmetry plane perpendicular to the laser polarization direction, the TDP can be neglected. Without such symmetry, however, the TDP will lead to the appearance of even harmonics. We further show that the TDP is sensitive to the crystal geometry. To extract the structure information from the harmonic spectra of a solid the TDP cannot be ignored.

  9. Isostructural solid-solid phase transition in monolayers of soft core-shell particles at fluid interfaces: structure and mechanics. (United States)

    Rey, Marcel; Fernández-Rodríguez, Miguel Ángel; Steinacher, Mathias; Scheidegger, Laura; Geisel, Karen; Richtering, Walter; Squires, Todd M; Isa, Lucio


    We have studied the complete two-dimensional phase diagram of a core-shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid-solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell-shell and core-core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core-core contacts nucleate, melting the surrounding shell-shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell-shell phase, followed by a steep increase upon the formation of a percolating network of the core-core contacts. These results demonstrate that the core-shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

  10. Extra phase noise from thermal fluctuations in nonlinear optical crystals

    DEFF Research Database (Denmark)

    César, J. E. S.; Coelho, A.S.; Cassemiro, K.N.


    We show theoretically and experimentally that scattered light by thermal phonons inside a second-order nonlinear crystal is the source of additional phase noise observed in optical parametric oscillators. This additional phase noise reduces the quantum correlations and has hitherto hindered the d...

  11. Stability of amorphous pharmaceutical solids: crystal growth mechanisms and effect of polymer additives. (United States)

    Sun, Ye; Zhu, Lei; Wu, Tian; Cai, Ting; Gunn, Erica M; Yu, Lian


    We review recent progress toward understanding and enhancing the stability of amorphous pharmaceutical solids against crystallization. As organic liquids are cooled to become glasses, fast modes of crystal growth can emerge. One such growth mode, the glass-to-crystal or GC mode, occurs in the bulk, and another exists at the free surface, both leading to crystal growth much faster than predicted by theories that assume diffusion defines the kinetic barrier of crystallization. These phenomena have received different explanations, and we propose that GC growth is a solid-state transformation enabled by local mobility in glasses and that fast surface crystal growth is facilitated by surface molecular mobility. In the second part, we review recent findings concerning the effect of polymer additives on crystallization in organic glasses. Low-concentration polymer additives can strongly inhibit crystal growth in the bulk of organic glasses, while having weaker effect on surface crystal growth. Ultra-thin polymer coatings can inhibit surface crystallization. Recent work has shown the importance of molecular weight for crystallization inhibitors of organic glasses, besides "direct intermolecular interactions" such as hydrogen bonding. Relative to polyvinylpyrrolidone, the VP dimer is far less effective in inhibiting crystal growth in amorphous nifedipine. Further work is suggested for better understanding of crystallization of amorphous organic solids and the prediction of their stability.

  12. Solid lubrication design methodology, phase 2 (United States)

    Pallini, R. A.; Wedeven, L. D.; Ragen, M. A.; Aggarwal, B. B.


    The high temperature performance of solid lubricated rolling elements was conducted with a specially designed traction (friction) test apparatus. Graphite lubricants containing three additives (silver, phosphate glass, and zinc orthophosphate) were evaluated from room temperature to 540 C. Two hard coats were also evaluated. The evaluation of these lubricants, using a burnishing method of application, shows a reasonable transfer of lubricant and wear protection for short duration testing except in the 200 C temperature range. The graphite lubricants containing silver and zinc orthophosphate additives were more effective than the phosphate glass material over the test conditions examined. Traction coefficients ranged from a low of 0.07 to a high of 0.6. By curve fitting the traction data, empirical equations for slope and maximum traction coefficient as a function of contact pressure (P), rolling speed (U), and temperature (T) can be developed for each lubricant. A solid lubricant traction model was incorporated into an advanced bearing analysis code (SHABERTH). For comparison purposes, preliminary heat generation calculations were made for both oil and solid lubricated bearing operation. A preliminary analysis indicated a significantly higher heat generation for a solid lubricated ball bearing in a deep groove configuration. An analysis of a cylindrical roller bearing configuration showed a potential for a low friction solid lubricated bearing.

  13. Hydrogen-bonding directed crystal engineering of some molecular solids (United States)

    Xue, Feng


    The design of crystalline clathrates and microporous solids is a contemporary goal in crystal engineering, in which hydrogen bonds play a central role because of their strength, directionality and flexibility. We have constructed various layer- and channel-type host structures by using hydrogen-bonding interactions. A novel hydrogen-bonded supramolecular rosette structure is generated from guanidinium and hydrogen carbonate ions in (1) and ( 2). The rosettes are fused into linear ribbons, which are cross-linked by terephthalate or 4-nitrobenzoate ions functioning as hydrogen-bond acceptors, resulting in anionic host layers with tetra-n-butylammonium guest species sandwiched between them. In (3) ˜ (6), new crystalline adducts of tetraalkylammonium terephthalate/trimesate with urea and water molecules result from hydrogen-bond directed assembly of complementary acceptors and donors that generate anionic channel- and layer-type host lattices for the accommodation of bulky hydrophobic cations. Some 4,4'-disubstituted biphenyls manifest their robustness and flexibility as supramolecular building blocks to construct host structures. 4,4'-biphenyl dicarboxylate ion has a strong tendency in generating ladder-type structure in (7) ˜ (10) due to its rigidity and effectiveness as a bifunctional hydrogen-bond acceptor. In (11) ˜ (15), 4,4 '-dicyanobiphenyl, 4,4'-bipyridine-N,N '-dioxide and 4,4'-dinitrobiphenyl exhibit a constructive interplay of strong and weak hydrogen bond functionalities that generate robust synthons. 4-Tritylbenzoic acid crystallizes via the carboxyl dimer supramolecular synthon to produce a wheel-and-axle host lattice that includes different aromatic solvents in its microporous framework in (16) ˜ (25 ), in which the host architecture is robust and yet adaptive. Based on the trigonal symmetry of 2,4,6-tris-4-(halo-phenoxy)-1,3,5-triazines (halo = chloro, bromo) and the Br3 or Cl3 supramolecular synthon, a new hexagonal host lattice has been designed

  14. Automated solid-phase synthesis of oligosaccharides containing sialic acids

    Directory of Open Access Journals (Sweden)

    Chian-Hui Lai


    Full Text Available A sialic acid glycosyl phosphate building block was designed and synthesized. This building block was used to prepare α-sialylated oligosaccharides by automated solid-phase synthesis selectively.

  15. Crystal growth within a phase change memory cell. (United States)

    Sebastian, Abu; Le Gallo, Manuel; Krebs, Daniel


    In spite of the prominent role played by phase change materials in information technology, a detailed understanding of the central property of such materials, namely the phase change mechanism, is still lacking mostly because of difficulties associated with experimental measurements. Here, we measure the crystal growth velocity of a phase change material at both the nanometre length and the nanosecond timescale using phase-change memory cells. The material is studied in the technologically relevant melt-quenched phase and directly in the environment in which the phase change material is going to be used in the application. We present a consistent description of the temperature dependence of the crystal growth velocity in the glass and the super-cooled liquid up to the melting temperature.

  16. Combinatorial Solid-Phase Synthesis of Balanol Analogues

    DEFF Research Database (Denmark)

    Nielsen, John; Lyngsø, Lars Ole


    The natural product balanol has served as a template for the design and synthesis of a combinatorial library using solid-phase chemistry. Using a retrosynthetic analysis, the structural analogues have been assembled from three relatively accessible building blocks. The solid-phase chemistry inclu...... including MSNT-mediated esterification of both support-bound alcohols and carboxylic acids has been implemented successfully. Copyright (C) 1996 Elsevier Science Ltd....

  17. Solid-phase synthesis of peptide - metal-complex conjugates


    Dirscherl, Georg


    The synthesis of Fmoc protected SAAC and their use in solid-phase synthesis is reported. Peptide � metal complex conjugates were either obtained by incorporation of the metal coordinated SAAC followed by mild nucleophilic resin-cleavage or by complexation in metal salt solution after cleavage from the resin. The reported solid phase peptide synthesis protocols are suitable for automation and the position and number of the modified amino acid within the peptide chain may vary. This allows the ...

  18. In situ Spectroscopy of Solid-State Chemical Reaction in PbBr2-Deposited CsBr Crystals (United States)

    Kondo, Shin-ichi; Matsunaga, Toshihiro; Saito, Tadaaki; Asada, Hiroshi


    It is possible to measure the fundamental optical absorption spectra of CsPbBr3 and Cs4PbBr6, whose stability is predicted by the study of phase diagram in the binary system CsBr-PbBr2, by means of in situ optical absorption and reflection spectroscopy of thermally induced solid-state chemical reaction in PbBr2-deposited CsBr crystals. On heavy annealing of the crystals, the Pb2+ ions are uniformly dispersed in the crystal matrix. The present experiment provides a novel method for measuring intrinsic optical absorption of ternary metal halides and also for in situ monitoring of doping metal halide crystal with impurities (metal ions or halogen ions).

  19. Interface dynamics and crystal phase switching in GaAs nanowires (United States)

    Jacobsson, Daniel; Panciera, Federico; Tersoff, Jerry; Reuter, Mark C.; Lehmann, Sebastian; Hofmann, Stephan; Dick, Kimberly A.; Ross, Frances M.


    Controlled formation of non-equilibrium crystal structures is one of the most important challenges in crystal growth. Catalytically grown nanowires are ideal systems for studying the fundamental physics of phase selection, and could lead to new electronic applications based on the engineering of crystal phases. Here we image gallium arsenide (GaAs) nanowires during growth as they switch between phases as a result of varying growth conditions. We find clear differences between the growth dynamics of the phases, including differences in interface morphology, step flow and catalyst geometry. We explain these differences, and the phase selection, using a model that relates the catalyst volume, the contact angle at the trijunction (the point at which solid, liquid and vapour meet) and the nucleation site of each new layer of GaAs. This model allows us to predict the conditions under which each phase should be observed, and use these predictions to design GaAs heterostructures. These results could apply to phase selection in other nanowire systems.

  20. Understanding the Cubic Phase Stabilization and Crystallization Kinetics in Mixed Cations and Halides Perovskite Single Crystals. (United States)

    Xie, Li-Qiang; Chen, Liang; Nan, Zi-Ang; Lin, Hai-Xin; Wang, Tan; Zhan, Dong-Ping; Yan, Jia-Wei; Mao, Bing-Wei; Tian, Zhong-Qun


    The spontaneous α-to-δ phase transition of the formamidinium-based (FA) lead halide perovskite hinders its large scale application in solar cells. Though this phase transition can be inhibited by alloying with methylammonium-based (MA) perovskite, the underlying mechanism is largely unexplored. In this Communication, we grow high-quality mixed cations and halides perovskite single crystals (FAPbI3)1-x(MAPbBr3)x to understand the principles for maintaining pure perovskite phase, which is essential to device optimization. We demonstrate that the best composition for a perfect α-phase perovskite without segregation is x = 0.1-0.15, and such a mixed perovskite exhibits carrier lifetime as long as 11.0 μs, which is over 20 times of that of FAPbI3 single crystal. Powder XRD, single crystal XRD and FT-IR results reveal that the incorporation of MA+ is critical for tuning the effective Goldschmidt tolerance factor toward the ideal value of 1 and lowering the Gibbs free energy via unit cell contraction and cation disorder. Moreover, we find that Br incorporation can effectively control the perovskite crystallization kinetics and reduce defect density to acquire high-quality single crystals with significant inhibition of δ-phase. These findings benefit the understanding of α-phase stabilization behavior, and have led to fabrication of perovskite solar cells with highest efficiency of 19.9% via solvent management.

  1. The Structural Phase Transition in Solid DCN

    DEFF Research Database (Denmark)

    Dietrich, O. W.; Mackenzie, Gordon A.; Pawley, G. S.


    Neutron scattering measurements on deuterated hydrogen cyanide have shown that the structural phase change from a tetragonal to an orthorhombic form at 160K is a first-order transition. A transverse acoustic phonon mode, which has the symmetry of the phase change, was observed at very low energies...... and showed 'softening' as the transition temperature was approached from above....

  2. Fabrication of Phase-Change Polymer Colloidal Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Tianyi Zhao


    Full Text Available This paper presents the preparation of phase-change polymer colloidal photonic crystals (PCs by assembling hollow latex spheres encapsulated with dodecanol for the first time. The monodispersed hollow latex spheres were obtained by phase reversion of monodispersed core-shell latex spheres in the n-hexane, which dissolves the PS core and retains the PMMA/PAA shell. The as-prepared phase-change colloidal PCs show stable phase-change behavior. This fabrication of phase-change colloidal PCs would be significant for PC’s applications in functional coatings and various optic devices.

  3. Fabrication of Phase-Change Polymer Colloidal Photonic Crystals


    Tianyi Zhao; Youzhuan Zhang; Jingxia Wang; Yanlin Song; Lei Jiang


    This paper presents the preparation of phase-change polymer colloidal photonic crystals (PCs) by assembling hollow latex spheres encapsulated with dodecanol for the first time. The monodispersed hollow latex spheres were obtained by phase reversion of monodispersed core-shell latex spheres in the n-hexane, which dissolves the PS core and retains the PMMA/PAA shell. The as-prepared phase-change colloidal PCs show stable phase-change behavior. This fabrication of phase-change colloidal PCs woul...

  4. Application of the phase method in radioisotope measurements of the liquid - solid particles flow in the vertical pipeline

    Directory of Open Access Journals (Sweden)

    Hanus Robert


    Full Text Available The paper presents idea and an application of the gamma-absorption method to a two-phase flow investigation in a vertical pipeline, where the flow of solid particles transported by water was examined by a set of two 241Am radioactive sources and probes with NaI(Tl scintillation crystals. In the described experiments as solid phase the ceramic models representing natural polymetallic ocean nodules were used. For advanced analysis of electrical signals obtained from detectors the phase of cross-spectral density function has been applied. Results of the average solid-phase velocity measurements were compared with one obtained by application of the classical cross-correlation. It was found that the combined uncertainties of the velocity of solid particles evaluation in the presented experiment did not exceed 0.6% in phase method and 3.2% in cross-correlation method.

  5. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R.; Chen, Long-Qing (Penn); (Xian Jiaotong); (CIW); (Simon); (TRS Techn); (Wollongong)


    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50–80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  6. Multiple topological phase transitions in a gyromagnetic photonic crystal

    KAUST Repository

    Chen, Zeguo


    We present the design of a tunable two-dimensional photonic crystal that exhibits multiple topological phases, including a conventional insulator phase, a quantum spin Hall phase, and a quantum anomalous Hall phase under different combinations of geometric parameters and external magnetic fields. Our photonic crystal enables a platform to study the topology evolution attributed to the interplay between crystalline symmetry and time-reversal symmetry. A four-band tight-binding model unambiguously reveals that the topological property is associated with the pseudospin orientations and that it is characterized by the spin Chern number. The emerging quantum anomalous Hall phase features a single helical edge state that is locked by a specific pseudospin. Simulation results demonstrate that the propagation of such a single helical edge state is robust against magnetic impurities. Potential applications, such as spin splitters, are described.

  7. Formation of ultrathin Ni germanides: solid-phase reaction, morphology and texture (United States)

    van Stiphout, K.; Geenen, F. A.; De Schutter, B.; Santos, N. M.; Miranda, S. M. C.; Joly, V.; Detavernier, C.; Pereira, L. M. C.; Temst, K.; Vantomme, A.


    The solid-phase reaction of ultrathin (⩽10 nm) Ni films with different Ge substrates (single-crystalline (1 0 0), polycrystalline, and amorphous) was studied. As thickness goes down, thin film texture becomes a dominant factor in both the film’s phase formation and morphological evolution. As a consequence, certain metastable microstructures are epitaxially stabilized on crystalline substrates, such as the ɛ-Ni5Ge3 phase or a strained NiGe crystal structure on the single-crystalline substrates. Similarly, the destabilizing effect of axiotaxial texture on the film’s morphology becomes more pronounced as film thicknesses become smaller. These effects are contrasted by the evolution of germanide films on amorphous substrates, on which neither epitaxy nor axiotaxy can form, i.e. none of the (de)stabilizing effects of texture are observed. The crystallization of such amorphous substrates however, drives the film breakup.

  8. Crystallization and Characterization of Galdieria sulphuraria RUBISCO in Two Crystal Forms: Structural Phase Transition Observed in P21 Crystal Form

    Directory of Open Access Journals (Sweden)

    Boguslaw Stec


    Full Text Available We have isolated ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCOfrom the red algae Galdieria Sulphuraria. The protein crystallized in two different crystalforms, the I422 crystal form being obtained from high salt and the P21 crystal form beingobtained from lower concentration of salt and PEG. We report here the crystallization,preliminary stages of structure determination and the detection of the structural phasetransition in the P21 crystal form of G. sulphuraria RUBISCO. This red algae enzymebelongs to the hexadecameric class (L8S8 with an approximate molecular weight 0.6MDa.The phase transition in G. sulphuraria RUBISCO leads from two hexadecamers to a singlehexadecamer per asymmetric unit. The preservation of diffraction power in a phasetransition for such a large macromolecule is rare.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  10. Solid state characterization of hydroxyprocaine hydrochloride. Crystal polymorphism of local anaesthetic drugs, part VIII (United States)

    Schmidt, A. C.; Schwarz, I.


    Two polymorphic and a pseudopolymorphic crystal form of the local anaesthetic drug hydroxyprocaine hydrochloride (4-Butylamino-2-hydroxybenzoic acid 2-dimethylaminoethyl ester hydrochloride, HPCHC) are characterized by thermal analysis (hot stage microscopy, differential scanning calorimetry, thermogravimetry), spectroscopy (FTIR-, FT-Raman-, SSNMR-spectroscopy), powder X-ray diffractometry and water vapor sorption analysis. The formation and thermodynamic stability of the different solid phases is described and presented in a flow chart and in an energy/temperature diagram, respectively. Mod. II° is the thermodynamically stable form at room temperature and present in commercial products mostly contaminated with a hydrated form which is isostructural with the unstable mod. I. The stable mod. II° crystallizes from most organic solvents in combination with seeds of the metastable mod. I and from the melt below 130 °C. Pure mod. I crystallizes from the melt at temperatures above 130 °C and additionally appears on dehydration of the hydrate. According to the heat of fusion rule, mod. I is the thermodynamically less stable form below the transition temperature (enantiotropism). The sorption isotherms show a distinct lower hygroscopicity for the stable mod. II°, whereas the unstable mod. I converts to the hydrate under moisture conditions above 0% RH at room temperature.

  11. N-Acyliminium Intermediates in Solid-Phase Synthesis

    DEFF Research Database (Denmark)

    Quement, Sebastian Thordal le; Petersen, Rico; Meldal, M.


    N-Acyliminium ions are powerful intermediates in synthetic organic chemistry. Examples of their use are numerous in solution-phase synthesis, but there are unmerited few reports on these highly reactive electrophiles in solid-phase synthesis. The present review covers the literature to date and i...

  12. Analytical techniques for small molecule solid phase synthesis. (United States)

    Scicinski, Jan J; Congreveb, Miles S; Kay, Corinne; Ley, Steven V


    Although resin-based chemistry offers many practical advantages over conventional solution phase for the synthesis of combinatorial libraries, effective monitoring of reactions conducted on the support remains a challenge. A number of techniques have been developed to enable the analysis of solid phase organic synthesis either by monitoring the resin-bound species directly or by the analysis of small quantities of material cleaved from the support. This review outlines some of the principles of the various techniques for the analysis of intermediates and products obtained from solid-phase chemistry.

  13. Solid phase fermentation of untreated leaf biomass to biogas

    Energy Technology Data Exchange (ETDEWEB)

    Chanakya, H.N.; Borgaonkar, S.; Meena, G.; Jagadish, K.S. (Indian Inst. of Science, Bangalore (India))


    Solid phase fermentation is a simple alternative to overcome problems in conventional slurry-based biogas digesters such as feedstock addition, floating scum, feed stratification and spent material discharge. The present study demonstrates the potential for a semi-continuous mode of operation. Laboratory scale solid phase digesters were operated with intact, untreated leaf biomass feedstock in a weekly-fed, batch mode without spent material removal for a period of 300 days. High biogas production rates were achieved by a twice daily sprinkling of the biomass bed with recycled liquid phase containing biodegradative bacteria. Results indicate that acidogenesis and methanogenesis occur at different layers of the decomposing bed. This simplifies feeding so that untreated leaf biomass may simply be added on top of the existing biomass bed in the digester without the need for feeding through a conventional liquid trap. Over 92% of the gas production was from the solid phase. (author)

  14. Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

    CERN Document Server

    Topolov, Vitaly


    The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

  15. Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted phthalocyanine and tetrabenzotriazaporphyrin (United States)

    Ohmori, Masashi; Nakano, Chika; Fujii, Akihiko; Shimizu, Yo; Ozaki, Masanori


    Selective crystal growth of polymorphs and crystal-to-crystal thermal phase transition of non-peripherally alkyl-substituted macrocycle molecules, such as octapentylphthalocyanine (C5PcH2), octahexylphthalocyanine (C6PcH2), and octahexyltetrabenzotriazaporphyrin (C6TBTAPH2) have been investigated. Two types of single crystals, called α-type and β-type, were separately grown by controlling the recrystallization conditions, and the crystal structures were determined by single-crystal X-ray structure analysis. The irreversible crystal-to-crystal thermal phase transition from α-type to β-type were observed by the differential scanning calorimetry and temperature-controlled X-ray structure analysis. The selective crystal growth of the α-type or β-type and the irreversible crystal-to-crystal thermal phase transition have been discussed by taking the alkyl-substituent distribution into consideration.

  16. Origins of Kerr phase and orientational phase in polymer-dispersed liquid crystal (United States)

    Chang, Chia-Ming; Lin, Yi-Hsin; Reshetnyak, Victor; Park, Chui Ho; Manda, Ramesh; Lee, Seung Hee


    The anisotropic properties of nematic liquid crystals result in polarization dependency which leads to requirement of at least a polarizer in liquid crystal photonic devices. To develop polarizer free phase modulation, Kerr effect is one of the path. The phase modulation in polymer dispersed liquid crystals (PDLCs) is shown to have two parts: Kerr phase, which is the optical phase modulation linearly proportional to a square of electric field, and orientational phase. However, many puzzles are still under investigation: the origins of Kerr phase, the relation between Kerr phase and orientational phase, and how two-steps of electro-optical (EO) response relates to Kerr phase and orientational phase. We investigated the origins of Kerr phase and orientational phase in PDLC and their connection to two-step EO response. In our study, the Kerr phase is a result of LC orientation in the center of LC droplets. The orientational phase attribute to orientation of LC molecules near LC-polymer interfaces. The two phase in PDLC samples are adjustable depending on droplet size. We also found that two-steps EO response existing in small droplet (<33 nm) is related to Kerr phase and orientational phase. A modified PDLC model related to the Kerr phase and orientational phase is also proposed. Besides the conventional features of PDLC, such as polarization independent optical phase shift and response time independent of cell gap, we believe the Kerr phase and orientational phase with different response times ( msec) in PDLC pave a way for designing versatile photonic devices with pure optical phase modulation.

  17. Ice crystals classification using airborne measurements in mixing phase (United States)

    Sorin Vajaiac, Nicolae; Boscornea, Andreea


    This paper presents a case study of ice crystals classification from airborne measurements in mixed-phase clouds. Ice crystal shadow is recorded with CIP (Cloud Imaging Probe) component of CAPS (Cloud, Aerosol, and Precipitation Spectrometer) system. The analyzed flight was performed in the south-western part of Romania (between Pietrosani, Ramnicu Valcea, Craiova and Targu Jiu), with a Beechcraft C90 GTX which was specially equipped with a CAPS system. The temperature, during the fly, reached the lowest value at -35 °C. These low temperatures allow the formation of ice crystals and influence their form. For the here presented ice crystals classification a special software, OASIS (Optical Array Shadow Imaging Software), developed by DMT (Droplet Measurement Technologies), was used. The obtained results, as expected are influenced by the atmospheric and microphysical parameters. The particles recorded where classified in four groups: edge, irregular, round and small.

  18. Ultra-directional source of longitudinal acoustic waves based on a two-dimensional solid/solid phononic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Morvan, B.; Tinel, A.; Sainidou, R.; Rembert, P. [Laboratoire Ondes et Milieux Complexes, UMR CNRS 6294, Université du Havre, 75 rue Bellot, 76058 Le Havre (France); Vasseur, J. O.; Hladky-Hennion, A.-C. [Institut d' Electronique, de Micro-électronique et de Nanotechnologie, UMR CNRS 8520, Cité Scientifique, 59652 Villeneuve d' Ascq Cedex (France); Swinteck, N.; Deymier, P. A. [Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721 (United States)


    Phononic crystals (PC) can be used to control the dispersion properties of acoustic waves, which are essential to direct their propagation. We use a PC-based two-dimensional solid/solid composite to demonstrate experimentally and theoretically the spatial filtering of a monochromatic non-directional wave source and its emission in a surrounding water medium as an ultra-directional beam with narrow angular distribution. The phenomenon relies on square-shaped equifrequency contours (EFC) enabling self-collimation of acoustic waves within the phononic crystal. Additionally, the angular width of collimated beams is controlled via the EFC size-shrinking when increasing frequency.

  19. Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

    Directory of Open Access Journals (Sweden)

    Xiaoyan Lu


    Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

  20. Metastable crystal growth of acetaminophen using solution-mediated phase transformation (United States)

    Mori, Yoichiro; Maruyama, Mihoko; Takahashi, Yoshinori; Yoshikawa, Hiroshi Y.; Okada, Shino; Adachi, Hiroaki; Sugiyama, Shigeru; Takano, Kazufumi; Murakami, Satoshi; Matsumura, Hiroyoshi; Inoue, Tsuyoshi; Yoshimura, Masashi; Mori, Yusuke


    We report a new method of obtaining the metastable phase form II crystals of acetaminophen. Solution-mediated phase transformation (SMPT) from trihydrate into form II is utilized to obtain form II crystals. SMPT is triggered by seeding form II crystals into a saturated solution including trihydrate crystals, which are less stable than form II crystals. Form II seed crystals gradually grew at the expense of the dissolving trihydrate crystals, and finally, all the trihydrate crystals in solution were transformed into form II crystals in about 4 h. Thus, we conclude that SMPT is effective for the production of form II crystals.

  1. Automating solid-phase extraction: current aspects and future prospects. (United States)

    Rossi, D T; Zhang, N


    This paper reviews current trends and techniques in automated solid-phase extraction. The area has shown a dramatic growth the number of manuscripts published over the last 10 years, including applications in environmental science, food science, clinical chemistry, pharmaceutical bioanalysis, forensics, analytical biochemistry and organic synthesis. This dramatic increase of more that 100% per year can be attributed to the commercial availability of higher throughput 96-well workstations and extraction plates that allow numerous samples to be processed simultaneously. These so-called parallel-processing workstations represent the highest throughput systems currently available. The advantages and limitations of other types of systems, including discrete column systems and on-line solid-phase extraction are also discussed. Discussions of how automated solid-phase extractions can be developed, generic approaches to automated solid-phase extraction, and three noteworthy examples of automated extractions are given. The last part of the review suggests possible near- and long-term directions of automated solid-phase extraction.

  2. Liquid-solid phase transition of Ge-Sb-Te alloy observed by in-situ transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Berlin, Katja, E-mail:; Trampert, Achim


    Melting and crystallization dynamics of the multi-component Ge-Sb-Te alloy have been investigated by in-situ transmission electron microscopy (TEM). Starting point of the phase transition study is an ordered hexagonal Ge{sub 1}Sb{sub 2}Te{sub 4} thin film on Si(111) where the crystal structure and the chemical composition are verified by scanning TEM and electron energy-loss spectroscopy, respectively. The in-situ observation of the liquid phase at 600°C including the liquid-solid and liquid-vacuum interfaces and their movements was made possible due to an encapsulation of the TEM sample. The solid-liquid interface during melting displays a broad and diffuse transition zone characterized by a vacancy induced disordered state. Although the velocities of interface movements are measured to be in the nanometer per second scale, both, for crystallization and solidification, the underlying dynamic processes are considerably different. Melting reveals linear dependence on time, whereas crystallization exhibits a non-linear time-dependency featuring a superimposed start-stop motion. Our results may provide valuable insight into the atomic mechanisms at interfaces during the liquid-solid phase transition of Ge-Sb-Te alloys. - Highlights: • In-situ TEM observation of liquid Ge-Sb-Te phase transition due to encapsulation. • During melting: Observation of non-ordered interface transition due to premelting. • During solidification: Observation of non-linear time-dependent crystallization.

  3. Phase field simulations of ice crystal growth in sugar solutions

    NARCIS (Netherlands)

    Sman, Van Der R.G.M.


    We present the first model ever, that describes explicitly ice crystal growth in a sugar solution during freezing. This 2-D model uses the phase field method, supplemented with realistic, and predictive theories on the thermodynamics and (diffusion) kinetics of this food system. We have to make

  4. Solid phase epitaxial regrowth of (100)GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Almonte, Marlene Isabel [California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering


    This thesis showed that low temperature (250°C) SPE of stoichiometrically balanced ion implanted GaAs layers can yield good epitaxial recovery for doses near the amorphization threshold. For 250°C anneals, most of the regrowth occurred in the first 10 min. HRTEM revealed much lower stacking fault density in the co-implanted sample than in the As-only and Ga-only samples with comparable doses. After low temp annealing, the nonstoichiometric samples had a large number of residual defects. For higher dose implants, very high temperatures (700°C) were needed to remove residual defects for all samples. The stoichiometrically balanced layer did not regrow better than the Ga-only and As-only samples. The co-implanted sample exhibited a thinner amorphous layer and a room temperature (RT) annealing effect. The amorphous layer regrew about 5 nm, suggesting that stoichiometrically balanced amorphous layers can regrow even at RT. Mechanisms for solid phase crystallization in (100)GasAs is discussed: nucleation and growth of randomly oriented crystallites and SPE. These two mechanisms compete in compound semiconductors at much lower temperatures than in Si. For the low dose As-only and Ga-only samples with low-temp anneals, both mechanisms are active. For this amorphization threshold dose, crystallites remain in the amorphous layer for all as-implants. 250°C annealing showed recrystallization from the surface and bulk for these samples; for the co-implant, the mechanism is not evident.

  5. Forming a three-dimensional porous organic network via solid-state explosion of organic single crystals. (United States)

    Bae, Seo-Yoon; Kim, Dongwook; Shin, Dongbin; Mahmood, Javeed; Jeon, In-Yup; Jung, Sun-Min; Shin, Sun-Hee; Kim, Seok-Jin; Park, Noejung; Lah, Myoung Soo; Baek, Jong-Beom


    Solid-state reaction of organic molecules holds a considerable advantage over liquid-phase processes in the manufacturing industry. However, the research progress in exploring this benefit is largely staggering, which leaves few liquid-phase systems to work with. Here, we show a synthetic protocol for the formation of a three-dimensional porous organic network via solid-state explosion of organic single crystals. The explosive reaction is realized by the Bergman reaction (cycloaromatization) of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene. The origin of the explosion is systematically studied using single-crystal X-ray diffraction and differential scanning calorimetry, along with high-speed camera and density functional theory calculations. The results suggest that the solid-state explosion is triggered by an abrupt change in lattice energy induced by release of primer molecules in the 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene crystal lattice.

  6. Azimuthal polarization states for the optimization of a liquid crystal display Sony LCX038ARA in the pure-phase regime (United States)

    Salamanca Vela, C. J.; Torres Moreno, Y.; Barrero Perez, J.; Acevedo Caceres, C.


    A liquid crystal display is an optoelectronic device contains molecules in an intermediate state between solid and liquid. In this work are showed numerical and experimental results of the azimuthal polarization states, which are used to optimize the pure-phase modulation of a Sony LCX038ARA LCD liquid crystal display for a linear polarized light beam with wavelength 632.8nm.

  7. Concept and early development of solid-phase peptide synthesis. (United States)

    Merrifield, B


    There are several reasons for the success of the solid-phase approach to peptide synthesis. The first is the ease of the procedure, the acceleration of the overall process, and the ability to achieve good yields of purified products. The second was the unanticipated discovery of many new biologically active peptides and the expanded need for synthetic peptides to help solve problems in virtually all disciplines of biology. In many cases, the solid-phase technique has been the method of choice. This approach, of course, does not replace the classic solution synthesis methods, but rather supplements them. The choice of techniques depends on the objectives of the synthesis. When carefully worked out, the solution methods can give high yields of highly purified products in large quantities. Many superb syntheses of active peptides have been achieved in this way. The solid-phase method has also yielded many large active peptides. It is particularly useful when large numbers of analogs, in relatively small quantities, are required as in structure-function studies on hormones, growth factors, antibiotics, and other biologically active peptides or for determining the antigenic epitopes of proteins. In addition, it has on occasion been scaled up for production of kilogram quantities. One of the unique uses of solid-phase synthesis has been the synthesis of peptide libraries. Most of the work on this new field in which thousands or millions of peptides are prepared simultaneously has been by solid-phase methods. This new technique is proving to be of great practical importance in rapid drug discovery of peptide, peptide mimetic, and nonpeptide compounds. Developments in screening methods now allow the examination of large numbers of compounds, and active products with structures unpredictable from natural product sequences are being found in this way. The properties of the solid-phase system, the changes in the chemistry, and the applications of the technique to biological

  8. Structural phase transitions and topological defects in ion Coulomb crystals

    Energy Technology Data Exchange (ETDEWEB)

    Partner, Heather L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Nigmatullin, Ramil [Institute of Quantum Physics, Ulm Univ., Ulm (Germany); Burgermeister, Tobias [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Keller, Jonas [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Pyka, Karsten [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Plenio, Martin B. [Center for Integrated Quantum Science and Technology, Ulm Univ., Ulm, (Germany):Institute for Theoretical Physics, Ulm Univ.,Ulm, (Germany); Retzker, Alex [Racah Institute of Physics, The Hebrew University of Jerusalem, Givat Ram (Israel); Zurek, Wojciech Hubert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); del Campo, Adolfo [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Physics; Mehlstaubler, Tanja E. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)


    We use laser-cooled ion Coulomb crystals in the well-controlled environment of a harmonic radiofrequency ion trap to investigate phase transitions and defect formation. Topological defects in ion Coulomb crystals (kinks) have been recently proposed for studies of nonlinear physics with solitons and as carriers of quantum information. Defects form when a symmetry breaking phase transition is crossed non-adiabatically. For a second order phase transition, the Kibble-Zurek mechanism predicts that the formation of these defects follows a power law scaling in the rate of the transition. We demonstrate a scaling of defect density and describe kink dynamics and stability. We further discuss the implementation of mass defects and electric fields as first steps toward controlled kink preparation and manipulation.

  9. Solid dispersions of Myricetin with enhanced solubility: Formulation, characterization and crystal structure of stability-impeding Myricetin monohydrate crystals (United States)

    Mureşan-Pop, M.; Pop, M. M.; Borodi, G.; Todea, M.; Nagy-Simon, T.; Simon, S.


    Three solid dispersion forms of Myricetin combined with the Polyvinylpyrrolidone were successfully prepared by spray drying method, and characterized by X-ray powder diffraction, thermal analysis, infrared spectroscopy and optical microscopy. Zeta potential measurements provided indications on solid dispersions stability in aqueous suspension related to their storage at elevated temperature and relative humidity, which depends on the Myricetin load. By increase of Myricetin load, the stability of the solid dispersion is impeded due to growth of Myricetin monohydrate crystals. The amorphous dispersions with 10% and 50% Myricetin load are stable and, compared to pure Myricetin, their aqueous solubility is enhanced by a factor of 47 and 13, respectively. The dispersion with 80% Myricetin load is unstable on storage, and this behavior acts in conjunction with the development of Myricetin monohydrate crystals. Single-crystal X-ray diffraction results obtained for Myricetin monohydrate reveal a structure of an infinite 2D network of hydrogen-bonded molecules involving all six hydroxyl groups of Myricetin. The water molecules are positioned in between the infinite chains, and contribute via H-bonds to robust crystal packing. The calculated needle-like morphology of monohydrate form is in agreement with the optical microscopy results. The study shows that the solid amorphous dispersions with up to 50% Myricetin load are a viable option for achieving substantial solubility improvement of Myricetin, and supports their potential use in pharmaceutical applications.

  10. Silica nanoparticle doped organic ionic plastic crystal electrolytes for highly efficient solid-state dye-sensitized solar cells. (United States)

    Shi, Chengzhen; Qiu, Lihua; Chen, Xiaojian; Zhang, Haigang; Wang, Lei; Yan, Feng


    Organic ionic plastic crystal, 1-propyl-1-methylpyrrolidinium iodide (P₁₃I), which possesses a broad plastic phase from -36 to 135 °C, was doped with silica nanoparticles (SiO₂ NPs) and 1-ethyl-3-methylimidazolium iodide (EMII), for the preparation of SiO₂/EMII/P₁₃I solid-state electrolytes for dye-sensitized solar cells (DSSCs). The thermal properties of all the electrolytes, including solid-solid phase transitions and melting temperatures, were investigated by differential scanning calorimetry (DSC). The effect of silica particles on the ionic conductivity, diffusion of I⁻/I₃⁻ redox couple in electrolytes, and photovoltaic performance for solid-state DSSCs were investigated. The fabricated solid-state DSSCs yielded a high power conversion efficiency of 5.25% under simulated air mass 1.5 solar spectrum illuminations at 50 mW cm⁻². Furthermore, the DSSCs based on SiO₂/EMII/P₁₃I solid-state electrolytes show good stability after an accelerating aging test, demonstrating potential practical applications.

  11. Crystal nucleation and dendrite growth of metastable phases in undercooled melts

    Energy Technology Data Exchange (ETDEWEB)

    Herlach, Dieter, E-mail: [Institut fuer Materialphysik im Weltraum, Deutsches Zentrum fuer Luft- und Raumfahrt, D-51170 Koeln (Germany)


    Research highlights: > Homogenous nucleation. > Effects of convection on dendrite growth kinetics. > Description of disorder trapping validated by experiment. - Abstract: An undercooled melt possesses an enhanced free enthalpy that opens up the possibility to crystallize metastable crystalline solids in competition with their stable counterparts. Crystal nucleation selects the crystallographic phase whereas the growth dynamics controls microstructure evolution. We apply containerless processing techniques such as electromagnetic and electrostatic levitation to containerlesss undercool and solidify metallic melts. Owing to the complete avoidance of heterogeneous nucleation on container-walls a large undercooling range becomes accessible with the extra benefit that the freely suspended drop is direct accessible for in situ observation of crystallization far away from equilibrium. Results of investigations of maximum undercoolability on pure zirconium are presented showing the limit of maximum undercoolability set by the onset of homogeneous nucleation. Rapid dendrite growth is measured as a function of undercooling by a high-speed camera and analysed within extended theories of non-equilibrium solidification. In such both supersaturated solid solutions and disordered superlattice structure of intermetallics are formed at high growth velocities. A sharp interface theory of dendrite growth is capable to describe the non-equilibrium solidification phenomena during rapid crystallization of deeply undercooled melts. Eventually, anomalous growth behaviour of Al-rich Al-Ni alloys is presented, which may be caused by forced convection.

  12. Mechanochromism of piroxicam accompanied by intermolecular proton transfer probed by spectroscopic methods and solid-phase changes. (United States)

    Sheth, Agam R; Lubach, Joseph W; Munson, Eric J; Muller, Francis X; Grant, David J W


    Structural and solid-state changes of piroxicam in its crystalline form under mechanical stress were investigated using cryogenic grinding, powder X-ray diffractometry, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, variable-temperature solid-state (13)C nuclear magnetic resonance spectroscopy, and solid-state diffuse-reflectance infrared Fourier transform spectroscopy. Crystalline piroxicam anhydrate exists as colorless single crystals irrespective of the polymorphic form and contains neutral piroxicam molecules. Under mechanical stress, these crystals become yellow amorphous piroxicam, which has a strong propensity to recrystallize to a colorless crystalline phase. The yellow color of amorphous piroxicam is attributed to charged piroxicam molecules. Variable-temperature solid-state (13)C NMR spectroscopy indicates that most of the amorphous piroxicam consists of neutral piroxicam molecules; the charged species comprise only about 8% of the amorphous phase. This ability to quantify the fractions of charged and neutral molecules of piroxicam in the amorphous phase highlights the unique capability of solid-state NMR to quantify mixtures in the absence of standards. Other compounds of piroxicam, which are yellow, are known to contain zwitterionic piroxicam molecules. The present work describes a system in which proton transfer accompanies both solid-state disorder and a change in color induced by mechanical stress, a phenomenon which may be termed mechanochromism of piroxicam.

  13. Quantum Phase Transitions around the Staggered Valence Bond Solid


    Xu, Cenke; Balents, Leon


    Motivated by recent numerical results, we study the quantum phase transitions between Z_2 spin liquid, Neel ordered, and various valence bond solid (VBS) states on the honeycomb and square lattices, with emphasis on the staggered VBS. In contrast to the well-understood columnar VBS order, the staggered VBS is not described by an XY order parameter with Z_N anisotropy close to these quantum phase transitions. Instead, we demonstrate that on the honeycomb lattice, the staggered VBS is more appr...

  14. Kinetically driven ordered phase formation in binary colloidal crystals (United States)

    Bochicchio, D.; Videcoq, A.; Ferrando, R.


    The aggregation of binary colloids of the same size and balanced charges is studied by Brownian dynamics simulations for dilute suspensions. It is shown that, under appropriate conditions, the formation of colloidal crystals is dominated by kinetic effects leading to the growth of well-ordered crystallites of the sodium-chloride (NaCl) bulk phase. These crystallites form with very high probability even when the cesium-chloride (CsCl) phase is more stable thermodynamically. Global optimization searches show that this result is not related to the most favorable structures of small clusters, which are either amorphous or of the CsCl structure. The formation of the NaCl phase is related to the specific kinetics of the crystallization process, which takes place by a two-step mechanism. In this mechanism, dense fluid aggregates form at first and then crystallization follows. It is shown that the type of short-range order in these dense fluid aggregates determines which phase is finally formed in the crystallites. The role of hydrodynamic effects in the aggregation process is analyzed by stochastic rotation dynamics - molecular dynamics simulations, and we find that these effects do not play a major role in the formation of the crystallites.

  15. Neutron Scattering Studies of Pre-Transitional Effects in Solid-Solid Phase Transformations

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, S. M.


    Neutron scattering studies have played a fundamental role in understanding solid-solid phase transformations, particularly in studying the lattice dynamical behavior associated with precursor effects. A review of the studies performed on solids exhibiting Martensitic transformations is given below. The mode softening and associated elastic diffuse scattering, previously observed in NiAl alloys, will be discussed as well as more recent work on Ni{sub 2}MnGa, a system exhibiting magnetic order as well as a Martensitic transformation. Also, new results on the precursor effects in ordered and disordered FePt alloys will be presented.

  16. Solid solutions of gadolinium doped zinc oxide nanorods by combined microwave-ultrasonic irradiation assisted crystallization (United States)

    Kiani, Armin; Dastafkan, Kamran; Obeydavi, Ali; Rahimi, Mohammad


    Nanocrystalline solid solutions consisting of un-doped and gadolinium doped zinc oxide nanorods were fabricated by a modified sol-gel process utilizing combined ultrasonic-microwave irradiations. Polyvinylpyrrolidone, diethylene glycol, and triethylenetetramine respectively as capping, structure directing, and complexing agents were used under ultrasound dynamic aging and microwave heating to obtain crystalline nanorods. Crystalline phase monitoring, lattice parameters and variation, morphology and shape, elemental analysis, functional groups, reducibility, and the oxidation state of emerged species were examined by PXRD, FESEM, TEM, EDX, FTIR, micro Raman, H2-TPR, and EPR techniques. Results have verified that irradiation mechanism of gelation and crystallization reduces the reaction time, augments the crystal quality, and formation of hexagonal close pack structure of Wurtzite morphology. Besides, dissolution of gadolinium within host lattice involves lattice deformation, unit cell distortion, and angular position variation. Structure related shape and growth along with compositional purity were observed through microscopic and spectroscopic surveys. Furthermore, TPR and EPR studies elucidated more detailed behavior upon exposure to the exerted irradiations and subsequent air-annealing including the formed oxidation states and electron trapping centers, presence of gadolinium, zinc, and oxygen disarrays and defects, as well as alteration in the host unit cell via gadolinium addition.

  17. A solid-state NMR method for solution of zeolite crystal structures. (United States)

    Brouwer, Darren H; Darton, Richard J; Morris, Russell E; Levitt, Malcolm H


    Since zeolites are notoriously difficult to prepare as large single crystals, structure determination usually relies on powder X-ray diffraction (XRD). However, structure solution (i.e., deriving an initial structural model) directly from powder XRD data is often very difficult due to the diffraction phase problem and the high degree of overlap between the individual reflections, particularly for materials with the structural complexity of most zeolites. Here, we report a method for structure determination of zeolite crystal structures that combines powder XRD and nuclear magnetic resonance (NMR) spectroscopy in which the crucial step of structure solution is achieved using solid-state (29)Si double-quantum dipolar recoupling NMR, which probes the distance-dependent dipolar interactions between naturally abundant (29)Si nuclei in the zeolite framework. For two purely siliceous zeolite blind test samples, we demonstrate that the NMR data can be combined with the unit cell parameters and space group to solve structural models that refine successfully against the powder XRD data.

  18. Crystallization kinetics and excess free energy of H2O and D2O nanoscale films of amorphous solid water. (United States)

    Smith, R Scott; Matthiesen, Jesper; Knox, Jake; Kay, Bruce D


    Temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS) are used to investigate the crystallization kinetics and measure the excess free energy of metastable amorphous solid water films (ASW) of H(2)O and D(2)O grown using molecular beams. The desorption rates from the amorphous and crystalline phases of ASW are distinct, and as such, crystallization manifests can be observed in the TPD spectrum. The crystallization kinetics were studied by varying the TPD heating rate from 0.001 to 3 K/s. A coupled desorption-crystallization kinetic model accurately simulates the desorption spectra and accurately predicts the observed temperature shifts in the crystallization. Isothermal crystallization studies using RAIRS are in agreement with the TPD results. Furthermore, highly sensitive measurements of the desorption rates were used to determine the excess free energy of ASW near 150 K. The excess entropy obtained from these data is consistent with there being a thermodynamic continuity between ASW and supercooled liquid water. © 2011 American Chemical Society

  19. Solid-phase biogas production with garbage or water hyacinth

    Energy Technology Data Exchange (ETDEWEB)

    Chanakya, H.N.; Borgaonkar, Sushama; Meena, G.; Jagadish, K.S. (Indian Inst. of Science, Bangalore (India). Centre for the Application of Science and Technology to Rural Areas (ASTRA))


    Fermentations of market garbage and water hyacinth in laboratory-scale solid-phase fermenters operated in fed batch mode is reported. Solid-phase fermentation was effected by a daily sprinkling of a weekly-fed biomass bed with an aqueous suspension of biodegradative bacteria to initiate and sustain high levels of biogas production. Gas production rates greater than 0.5 litres/litre per day at specific gas yields of 250-300 litres/kg total solids at residence times between 150 and 250 days were obtained. Major methanogenic activity appeared to occur in the lower parts of the decomposing bed, therefore feeding could be carried out on a once-weekly basis by opening the top of the fermenter and adding the untreated biomass feed, without deleterious effects on the overall gas yields or composition. The compaction of biomass feeds during decomposition permitted the use of high residence times without loss of space economy. (author)

  20. All solid-state SBS phase conjugate mirror (United States)

    Dane, C.B.; Hackel, L.A.


    A stimulated Brillouin scattering (SBS) phase conjugate laser mirror uses a solid-state nonlinear gain medium instead of the conventional liquid or high pressure gas medium. The concept has been effectively demonstrated using common optical-grade fused silica. An energy threshold of 2.5 mJ and a slope efficiency of over 90% were achieved, resulting in an overall energy reflectivity of >80% for 15 ns, 1 um laser pulses. The use of solid-state materials is enabled by a multi-pass resonant architecture which suppresses transient fluctuations that would otherwise result in damage to the SBS medium. This all solid state phase conjugator is safer, more reliable, and more easily manufactured than prior art designs. It allows nonlinear wavefront correction to be implemented in industrial and defense laser systems whose operating environments would preclude the introduction of potentially hazardous liquids or high pressure gases. 8 figs.

  1. Moisture-induced amorphous phase separation of amorphous solid dispersions: molecular mechanism, microstructure, and its impact on dissolution performance. (United States)

    Chen, Huijun; Pui, Yipshu; Liu, Chengyu; Chen, Zhen; Su, Ching-Chiang; Hageman, Michael; Hussain, Munir; Haskell, Roy; Stefanski, Kevin; Foster, Kimberly; Gudmundsson, Olafur; Qian, Feng


    Amorphous phase separation (APS) is commonly observed in amorphous solid dispersions (ASD) when exposed to moisture. The objective of this study was to investigate: 1) the phase behavior of amorphous solid dispersions composed of a poorly water-soluble drug with extremely low crystallization propensity, BMS-817399, and PVP, following exposure to different relative humidity (RH), and 2) the impact of phase separation on the intrinsic dissolution rate of amorphous solid dispersion. Drug-polymer interaction was confirmed in ASDs at different drug loading using Infrared (IR) spectroscopy and water vapor sorption analysis. It was found that the drug-polymer interaction could persist at low RH (≤ 75% RH) but was disrupted after exposure to high RH, with the advent of phase separation. Surface morphology and composition of 40/60 ASD at micro-/nano- scale before and after exposure to 95% RH were also compared. It was found that hydrophobic drug enriched on the surface of ASD after phase separation. However, for the 40/60 ASD system, the intrinsic dissolution rate of amorphous drug was hardly affected by the phase behavior of ASD, which may be partially attributed to the low crystallization tendency of amorphous BMS-817399 and high hydrophobicity of ASD. Intrinsic dissolution rate of PVP was decreased resulting from phase separation, leading to a lower concentration in the dissolution medium, but supersaturation maintenance was not anticipated to be altered after phase separation due to the limited ability of PVP to inhibit drug precipitation and prolong the supersaturation of drug in solution. This study indicated that for compounds with low crystallization propensity and high hydrophobicity, the risk of moisture-induced phase separation is high but such phase separation may not have profound impact on the drug dissolution performance of ASDs. Therefore, application of ASD technology on slow crystallizers could incur low risks not only in physical stability, but also in

  2. Tunable Crystal-to-Crystal Phase Transition in a Cadmium Halide Chain Polymer

    Directory of Open Access Journals (Sweden)

    Ulli Englert


    Full Text Available The chain polymer [{Cd(μ-X2py2}1∞] (X = Cl, Br; py = pyridine undergoes a fully reversible phase transition between a monoclinic low-temperature and an orthorhombic high-temperature phase. The transformation can be directly monitored in single crystals and can be confirmed for the bulk by powder diffraction. The transition temperature can be adjusted by tuning the composition of the mixed-halide phase: Transition temperatures between 175 K up to the decomposition of the material at ca. 350 K are accessible. Elemental analysis, ion chromatography and site occupancy refinements from single-crystal X-ray diffraction agree with respect to the stoichiometric composition of the samples.

  3. Solid-Phase Extraction Combined with High Performance Liquid ...

    African Journals Online (AJOL)

    Satisfactory precision was obtained both for intra-assay (RSD, 1.8 to 4.4 %) and inter-assay (RSD, 2.0 to 4.7 %). Conclusion: The proposed method is environmentally friendly, inexpensive and convenient, and should be helpful in analyzing estrogens in biological, environmental and food samples. Keywords: Solid-phase ...

  4. Solid-phase oligosaccharide and glycopeptide synthesis using glycosynthases

    DEFF Research Database (Denmark)

    Tolborg, Jakob Fjord; Petersen, Lars; Jensen, Knud Jørgen


    and the prospect of automatability. Here, we report the first application of glycosynthases to solid-phase oligosaccharide synthesis by use of the 51 kDa serine and glycine mutants of Agrobacterium sp. beta-glucosidase, Abg E358S and E358G. Acceptors were linked to PEGA resin through a backbone amide linker (BAL...

  5. Solid-phase synthesis of 3-amino-2-pyrazolines

    DEFF Research Database (Denmark)

    Nielsen, John


    The development of a solid-phase synthesis of 3-amino-2-pyrazolines is described. Conjugate addition of hydrazines to alpha,beta-unsaturated nitriles followed by cyclization yields 3-amino-2-pyrazolines. Acylation or sulfonation of the free amino-group yields a 24 member library of 3-amino-2...

  6. Solid-phase synthesis of 3-amino-2-pyrazolines

    DEFF Research Database (Denmark)

    Lyngsø, Lars O.; Nielsen, John


    The development of a solid-phase synthesis of 3-amino-2-pyrazolines is described. Conjugate addition of hydrazines to α,β-unsaturated nitriles followed by cyclization yields 3-amino-2-pyrazolines. Acylation or sulfonation of the free amino-group yields a 24 member library of 3-amino-2- pyrazolines....

  7. Solid Phase Characterization of Tank 241-C-105 Grab Samples

    Energy Technology Data Exchange (ETDEWEB)

    Ely, T. M. [Washington River Protection Solutions LLC, Richland, WA (United States); LaMothe, M. E. [Washington River Protection Solutions LLC, Richland, WA (United States); Lachut, J. S. [Washington River Protection Solutions LLC, Richland, WA (United States)


    The solid phase characterization (SPC) of three grab samples from single-shell Tank 241-C-105 (C-105) that were received at the laboratory the week of October 26, 2015, has been completed. The three samples were received and broken down in the 11A hot cells.

  8. Solid-phase synthesis of complex and pharmacologically interesting heterocycles

    DEFF Research Database (Denmark)

    Nielsen, Thomas Eiland


    Efficient routes for the creation of heterocycles continue to be one of the primary goals for solid-phase synthesis. Recent advances in this field rely most notably on transition-metal-catalysis and N-acyliminium chemistry to mediate a range of cyclization processes for the generation of compound...

  9. Solid-phase-supported synthesis of morpholinoglycine oligonucleotide mimics

    Directory of Open Access Journals (Sweden)

    Tatyana V. Abramova


    Full Text Available An efficient solid-phase-supported peptide synthesis (SPPS of morpholinoglycine oligonucleotide (MorGly mimics has been developed. The proposed strategy includes a novel specially designed labile linker group containing the oxalyl residue and the 2-aminomethylmorpholino nucleoside analogues as first subunits.

  10. Headspace solid-phase microextraction and gas chromatography ...

    African Journals Online (AJOL)

    Purpose: To extract and analyze the volatile components of Chrysanthemum morifolium Ramat. 'huaiju' by headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC–MS). Methods: Volatile components were extracted by HS-SPME and identified by GC–MS. The relative contents ...

  11. Headspace solid-phase microextraction and gas chromatography ...

    African Journals Online (AJOL)

    Purpose: To extract and analyze the volatile components of Chrysanthemum morifolium Ramat. 'huaiju' by headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry. (GC–MS). Methods: Volatile components were extracted by HS-SPME and identified by GC–MS. The relative contents ...

  12. Development and Application of Solid Phase Extraction Method for ...

    African Journals Online (AJOL)


    Solid phase extraction, polycyclic aromatic hydrocarbons, water samples, Johannesburg, South Africa. 1. Introduction. Polycyclic aromatic ... sewage and industrial effluents as well as for urban and rural run-off. Their solubility in ... human health and to the environment.2 Acute toxicity is gener- ally associated with the lower ...

  13. Study on the Solid Phase Extraction and Spectrophotometric ...

    African Journals Online (AJOL)


    thiorhodanine (ABTR) as a new chromogenic reagent for the determination of mercury. Based on the rapid reaction of mercury(II) with ABTR and the solid phase extraction of the coloured chelate with a C18 disk, a highly sensitive, selective and ...


    African Journals Online (AJOL)

    ABSTRACT. A novel method using a packed column with perlite as a new sorbent has been developed for preconcentration of trace amounts of zinc and cadmium prior to their determination by flame atomic absorption spectrometry. Several factors that may be affected on the solid phase extraction (SPE) process, such as ...

  15. Evaluation of the emulsifying property of solid phase purified ...

    African Journals Online (AJOL)

    This suggests the suitability of the purified oil as a base in the formulation of lotions and creams. Conclusion: The purified oil of G. kola possesses emulsifying property and could find applications in cosmetic and pharmaceutical industries. Keywords: Garcinia cola, seed oil, solid phase purification, emulsifying property ...

  16. Solid-phase microextraction for the analysis of biological samples

    NARCIS (Netherlands)

    Theodoridis, G; Koster, EHM; de Jong, GJ


    Solid-phase microextraction (SPME) has been introduced for the extraction of organic compounds from environmental samples. This relatively new extraction technique has now also gained a lot of interest in a broad field of analysis including food, biological and pharmaceutical samples. SPME has a

  17. Insight into solid-liquid phase transfer catalyzed synthesis of ...

    Indian Academy of Sciences (India)

    2-Methyl-4-chlorophenoxy propionic acid (Mecoprop) is a widely used household herbicide. In the current work, a simple synthetic method is developed for Mecoprop methyl ester using solid-liquid phase transfer catalysis (S-L PTC) with K₂CO₃ as mild base and toluene as solvent. Conversion of 95% was achieved with ...


    African Journals Online (AJOL)

    B. S. Chandravanshi

    indicating a purer extract. KEY WORDS: Khat alkaloids, Solid phase extraction, Liquid-liquid extraction, HPLC, Genevac. INTRODUCTION. Khat (Catha edulis Vahl. Endl.) is an evergreen shrub or tree belonging to the Celastraceae family. Although the plant originates from Ethiopia, it occurs in Kenya, Malawi, Uganda,.

  19. Determination of 8 Synthetic Food Dyes by Solid Phase Extraction ...

    African Journals Online (AJOL)

    Recovery was 94.2 % for Brilliant blue in jelly powder. Conclusion: This method was successfully applied to determine colorants in various (30) water-soluble foods, including fruit flavored drinks, sugar confectionery, sweets, etc. Keywords: Synthetic colors, Food, Fruit flavored drinks, Solid phase extraction, RP-HPLC ...

  20. Solid-Phase Extraction Combined with High Performance Liquid ...

    African Journals Online (AJOL)

    be helpful in analyzing estrogens in biological, environmental and food samples. Keywords: Solid-phase extraction, Milk, Estrogens, High ... systems are completely different from the traditional ones. Duo to the result of modern ... Therefore, to ensure the food safety and human health, it is essential to develop rapid, simple,.

  1. Kinetics of solid state phase transformations: Measurement and ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 122; Issue 1. Kinetics of solid state phase transformations: Measurement and modelling of some basic issues. S Raju E ... are enumerated. A simple and general modelling methodology for understanding the kinetics of non-isothermal transformations is outlined.

  2. Recent Approaches Toward Solid Phase Synthesis of β-Lactams (United States)

    Mandal, Bablee; Ghosh, Pranab; Basu, Basudeb

    Since the discovery of penicillin in 1929, β-lactam antibiotics have been recognized as potentially chemotherapeutic drugs of incomparable effectiveness, conjugating a broad spectrum of activity with very low toxicity. The primary motif azetidin-2-one ring (β-lactam) has been considered as specific pharmacophores and scaffolds. With the advent of combinatorial chemistry and automated parallel synthesis coupled with ample interests from the pharmaceutical industries, recent trends have been driven mostly by adopting solid phase techniques and polymer-supported synthesis of β-lactams. The present survey will present an overview of the developments on the polymer-supported and solid phase techniques for the preparation of β-lactam ring or β-lactam containing antibiotics published over the last decade. Both unsubstituted and substitutions with different functional groups at various positions of β-lactams have been synthesized using solid phase technology. However, Wang resin and application of Staudinger [2+2] cycloaddition reaction have remained hitherto the major choice. It may be expected that other solid phase approaches involving different resins would be developed in the coming years.

  3. Development of headspace solid-phase microextraction method for ...

    African Journals Online (AJOL)

    A headspace solid-phase microextraction (HS-SPME) method was developed as a preliminary investigation using univariate approach for the analysis of 14 multiclass pesticide residues in fruits and vegetable samples. The gas chromatography mass spectrometry parameters (desorption temperature and time, column flow ...

  4. Phase stabilities and mechanical properties of two new carbon crystals (United States)

    Liang, Y.; Zhang, W.; Chen, L.


    Density functional calculations are used to systematically evaluate phase stabilities and mechanical properties of two recently proposed carbon crystals (K4 and M-carbon), along with graphite, cubic diamond and hexagonal diamond. It is found that the K4 carbon, which can be referred to as a twin of the cubic diamond crystal, is mechanically unstable, implying that it cannot be formed. Remarkably, our calculations not only substantiate the M-carbon phase is a highly incompressible and potentially superhard material but also show that it exhibits mechanical stability. Moreover, a surprisingly small activation barrier (about 0.018 eV/atom) for the transformation of M-carbon to graphite explains some paradoxical experimental observations.

  5. Wave propagation in one-dimensional solid-fluid quasi-periodic and aperiodic phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ali, E-mail: [Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044 (China); Wang Yuesheng [Institute of Engineering Mechanics, Beijing Jiaotong University, Beijing 100044 (China); Zhang Chuanzeng [Department of Civil Engineering, University of Siegen, D-57068 Siegen (Germany)


    The propagation of the elastic waves in one-dimensional (1D) solid-fluid quasi-periodic phononic crystals is studied by employing the concept of the localization factor, which is calculated by the transfer matrix method. The solid-fluid interaction effect at the interfaces between the solid and the fluid components is considered. For comparison, the periodic systems and aperiodic Thue-Morse sequence are also analyzed in this paper. The splitting phenomenon of the pass bands and bandgaps are discussed for these 1D solid-fluid systems. At last the influences of the material impedance ratios on the band structures of the 1D solid-fluid quasi-periodic phononic crystals arranged as Fibonacci sequence are discussed.

  6. Special phase transformation and crystal growth pathways observed in nanoparticles†

    Directory of Open Access Journals (Sweden)

    Finnegan Michael P


    Full Text Available Phase transformation and crystal growth in nanoparticles may happen via mechanisms distinct from those in bulk materials. We combine experimental studies of as-synthesized and hydrothermally coarsened titania (TiO2 and zinc sulfide (ZnS with thermodynamic analysis, kinetic modeling and molecular dynamics (MD simulations. The samples were characterized by transmission electron microscopy, X-ray diffraction, synchrotron X-ray absorption and scattering, and UV-vis spectroscopy. At low temperatures, phase transformation in titania nanoparticles occurs predominantly via interface nucleation at particle–particle contacts. Coarsening and crystal growth of titania nanoparticles can be described using the Smoluchowski equation. Oriented attachment-based crystal growth was common in both hydrothermal solutions and under dry conditions. MD simulations predict large structural perturbations within very fine particles, and are consistent with experimental results showing that ligand binding and change in aggregation state can cause phase transformation without particle coarsening. Such phenomena affect surface reactivity, thus may have important roles in geochemical cycling.

  7. Unusual crystallization behavior in Ga-Sb phase change alloys

    Directory of Open Access Journals (Sweden)

    Magali Putero


    Full Text Available Combined in situ X-ray scattering techniques using synchrotron radiation were applied to investigate the crystallization behavior of Sb-rich Ga-Sb alloys. Measurements of the sheet resistance during heating indicated a reduced crystallization temperature with increased Sb content, which was confirmed by in situ X-ray diffraction. The electrical contrast increased with increasing Sb content and the resistivities in both the amorphous and crystalline phases decreased. It was found that by tuning the composition between Ga:Sb = 9:91 (in at.% and Ga:Sb = 45:55, the change in mass density upon crystallization changes from an increase in mass density which is typical for most phase change materials to a decrease in mass density. At the composition of Ga:Sb = 30:70, no mass density change is observed which should be very beneficial for phase change random access memory (PCRAM applications where a change in mass density during cycling is assumed to cause void formation and PCRAM device failure.

  8. Crystal phase of fibrous calcium phosphates prepared with sodium alginate. (United States)

    Hayashizaki, J; Ban, S; Arimoto, N; Kato, N; Kimura, Y; Hasegawa, J


    This study investigated the effects of preparation conditions on the crystal phase of the fired fiber prepared with sodium alginate. Hydroxyapatite, Ca10(PO4)6(OH)2, hereafter referred to as HA, was only formed in fiber fired at 900 degrees C under proper conditions. There was no significant difference in the crystal phase of the fired fibers prepared using different sodium alginate concentrations and syringe nozzle diameter, although fiber diameters were enlarged with increasing in either. No effects of phosphate type on the crystal phase of the fired fiber were found, but the aging time and the rinsing time had great effects. Sodium calcium phosphate, NaCaPO4, and HA were formed when the aging time was shorter than 5 min. Chlorapatite, Ca5Cl(PO4)3, and HA were formed when the rinsing time was shorter than 3 sec, and HA was formed when the rinsing time was 5 min to 1 hour, beta-TCP, beta-Ca3 (PO4)2, and HA were formed when the rinsing time exceeded 2 weeks.

  9. Plasticity and beyond microstructures, crystal-plasticity and phase transitions

    CERN Document Server

    Hackl, Klaus


    The book presents the latest findings in experimental plasticity, crystal plasticity, phase transitions, advanced mathematical modeling of finite plasticity and multi-scale modeling. The associated algorithmic treatment is mainly based on finite element formulations for standard (local approach) as well as for non-standard (non-local approach) continua and for pure macroscopic as well as for directly coupled two-scale boundary value problems. Applications in the area of material design/processing are covered, ranging from grain boundary effects in polycrystals and phase transitions to deep-drawing of multiphase steels by directly taking into account random microstructures.

  10. Spin-Crossover Molecular Solids Beyond Rigid Crystal Approximation. (United States)

    Gudyma, Iurii V; Ivashko, Victor V


    The qualitative analysis of the spin-crossover molecular solid with distortion effect is presented. A spin-crossover solid with effect of distortion is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on inter-ion interaction is considered. These considerations lead to examination of the relation between the primary and secondary order parameters during temperature and pressure changes.

  11. Tunable topological phases in photonic and phononic crystals

    KAUST Repository

    Chen, Zeguo


    Topological photonics/phononics, inspired by the discovery of topological insulators, is a prosperous field of research, in which remarkable one-way propagation edge states are robust against impurities or defect without backscattering. This dissertation discusses the implementation of multiple topological phases in specific designed photonic and phononic crystals. First, it reports a tunable quantum Hall phase in acoustic ring-waveguide system. A new three-band model focused on the topological transitions at the Γ point is studied, which gives the functionality that nontrivial topology can be tuned by changing the strengths of the couplings and/or the broken time-reversal symmetry. The resulted tunable topological edge states are also numerically verified. Second, based on our previous studied acoustic ring-waveguide system, we introduce anisotropy by tuning the couplings along different directions. We find that the bandgap topology is related to the frequency and directions. We report our proposal on a frequency filter designed from such an anisotropic topological phononic crystal. Third, motivated by the recent progress on quantum spin Hall phases, we propose a design of time-reversal symmetry broken quantum spin Hall insulators in photonics, in which a new quantum anomalous Hall phase emerges. It supports a chiral edge state with certain spin orientations, which is robust against the magnetic impurities. We also report the realization of the quantum anomalous Hall phase in phononics.


    Energy Technology Data Exchange (ETDEWEB)



    During sluicing operations of tank 241-C-110, a significant amount of solids were unable to be retrieved. These solids (often referred to as the tank 'heel') were sampled in 2010 and chemically and mineralogically analyzed in the 222-S Laboratory. Additionally, dissolution tests were performed to identify the amount of undissolvable material after using multiple water contacts. This report covers the solid phase characterization of six samples from these tests using scanning electron microscopy, polarized light microscopy, and X-ray diffraction. The chemical analyses, particle size distribution analysis, and dissolution test results are reported separately. Two of the samples were from composites created from as-received material - Composite A and Composite B. The main phase in these samples was sodium-fluoride-phosphate hydrate (natrophosphate) - in the X-ray diffraction spectra, this phase was the only phase identifiable. Polarized light microscopy showed the presence of minor amounts of gibbsite and other phases. These phases were identified by scanning electron microscopy - energy dispersive X-ray spectroscopy as sodium aluminosilicates, sodium diuranate, and sodium strontium phosphate hydrate (nastrophite) crystals. The natrophosphate crystals in the scanning electron microscopy analysis showed a variety of erosive and dissolution features from perfectly shaped octahedral to well-rounded appearance. Two samples were from water-washed Composites A and B, with no change in mineralogy compared to the as-received samples. This is not surprising, since the water wash had only a short period of water contact with the material as opposed to the water dissolution tests. The last two samples were residual solids from the water dissolution tests. These tests included multiple additions of water at 15 C and 45 C. The samples were sieved to separate a coarser fraction of > 710 {mu}m and a finer fraction of < 710 {mu}m. These two fractions were analyzed

  13. Solid-phase template-directed synthesis of a [2]rotaxane using a solid-phase stopper. (United States)

    Bravo, José A; Orain, David; Bradley, Mark


    The first synthesis of a rotaxane by solid phase chemistry has been achieved, using the resin bead as a 'Mega' stopper during the synthesis. One of the advantages of this methodology over traditional solution routes include the ability to use mass action to drive the chemistry, without complicating the purification process.

  14. Ribosomal crystallography: from crystal growth to initial phasing (United States)

    Thygesen, J.; Krumbholz, S.; Levin, I.; Zaytzev-Bashan, A.; Harms, J.; Bartels, H.; Schlünzen, F.; Hansen, H. A. S.; Bennett, W. S.; Volkmann, N.; Agmon, I.; Eisenstein, M.; Dribin, A.; Maltz, E.; Sagi, I.; Morlang, S.; Fua, M.; Franceschi, F.; Weinstein, S.; Böddeker, N.; Sharon, R.; Anagnostopoulos, K.; Peretz, M.; Geva, M.; Berkovitch-Yellin, Z.; Yonath, A.


    Preliminary phases were determined by the application of the isomorphous replacement method at low and intermediate resolution for structure factor amplitudes collected from crystals of large and small ribosomal subunits from halophilic and thermophilic bacteria. Derivatization was performed with dense heavy atom clusters, either by soaking or by specific covalent binding prior to the crystallization. The resulting initial electron density maps contain features comparable in size to those expected for the corresponding particles. The packing arrangements of these maps have been compared with motifs observed by electron microscopy in positively stained thin sections of embedded three-dimensional crystals, as well as with phase sets obtained by ab-initio computations. Aimed at higher resolution phasing, procedures are being developed for multi-site binding of relatively small dense metal clusters at selected locations. Potential sites are being inserted either by mutagenesis or by chemical modifications to facilitate cluster binding to the large halophilic and the small thermophilic ribosomal subunits which yield crystals diffracting to the highest resolution obtained so far for ribosomes, 2.9 and 7.3 Å, respectively. For this purpose the surfaces of these ribosomal particles have been characterized and conditions for quantitative reversible detachment of selected ribosomal proteins have been found. The corresponding genes are being cloned, sequenced, mutated to introduce the reactive side-groups (mainly cysteines) and overexpressed. To assist the interpretation of the anticipated electron density maps, sub-ribosomal stable complexes were isolated from H50S. One of these complexes is composed of two proteins and the other is made of a stretch of the rRNA and a protein. For exploiting the exposed parts of the surface of these complexes for heavy atom binding and for attempting the determination of their three-dimensional structure, their components are being produced

  15. Distribution of Dechlorinating Bacteria between the Aqueous and Solid Phases (United States)

    Cápiro, N. L.; Hatt, J. K.; Wang, Y.; Loeffler, F. E.; Pennell, K. D.


    Microbial monitoring of aquifers relies on nucleic acid biomarker analysis, which is typically performed with biomass recovered from groundwater samples; however, it is unclear what fraction of the target population(s) is associated with groundwater (i.e., planktonic cells) or is attached to solid phases (i.e., biofilms). Understanding how the titer of target organism(s) in groundwater correlates with the true cell titers of the target organism in the aquifer (i.e., planktonic plus attached cells) is critical for a meaningful interpretation of the data, the prediction of bioremediation performance, and the implementation of site management strategies. To evaluate the distribution of active cells between resident solid phase and the aqueous phase, one-dimensional columns were packed under water-saturated conditions with Bio-Dechlor INOCULUM, a PCE-to ethene-dechlorinating bacterial consortium containing both multiple Dehalococcoides (Dhc) strains and Geobacter lovleyi strain SZ (GeoSZ). The columns were packed with two distinct solid matrices: a low organic content sandy Federal Fine Ottawa soil or Appling soil with higher organic matter content. Influent reduced mineral salts medium supplied at a groundwater pore-water velocity of 0.3 m/day contained both 10 mM lactate as electron donor and 0.33 mM PCE as electron acceptor. Routine collection of biomass from column side ports and effluent samples measured the titers of target cells in the aqueous phase and determined when steady state conditions had been reached. A second set of column experiments evaluated delivery and filtration effects by the solid matrix (i.e., Federal Fine Ottawa sand versus Appling soil) under the same conditions except that electron donor or acceptor were omitted (no growth conditions). Quantitative real-time PCR (qPCR) analysis using Dhc and GeoSZ 16S rRNA gene-targeted primer and probe sets determined the planktonic cell counts, and destructive sampling of the columns allowed measurement

  16. Confined crystals of the smallest phase-change material. (United States)

    Giusca, Cristina E; Stolojan, Vlad; Sloan, Jeremy; Börrnert, Felix; Shiozawa, Hidetsugu; Sader, Kasim; Rümmeli, Mark H; Büchner, Bernd; Silva, S Ravi P


    The demand for high-density memory in tandem with limitations imposed by the minimum feature size of current storage devices has created a need for new materials that can store information in smaller volumes than currently possible. Successfully employed in commercial optical data storage products, phase-change materials, that can reversibly and rapidly change from an amorphous phase to a crystalline phase when subject to heating or cooling have been identified for the development of the next generation electronic memories. There are limitations to the miniaturization of these devices due to current synthesis and theoretical considerations that place a lower limit of 2 nm on the minimum bit size, below which the material does not transform in the structural phase. We show here that by using carbon nanotubes of less than 2 nm diameter as templates phase-change nanowires confined to their smallest conceivable scale are obtained. Contrary to previous experimental evidence and theoretical expectations, the nanowires are found to crystallize at this scale and display amorphous-to-crystalline phase changes, fulfilling an important prerequisite of a memory element. We show evidence for the smallest phase-change material, extending thus the size limit to explore phase-change memory devices at extreme scales.

  17. Observation of a New High-Pressure Solid Phase in Dynamically Compressed Aluminum (United States)

    Polsin, D. N.


    Aluminum is ideal for testing theoretical first-principles calculations because of the relative simplicity of its atomic structure. Density functional theory (DFT) calculations predict that Al transforms from an ambient-pressure, face-centered-cubic (fcc) crystal to the hexagonal close-packed (hcp) and body-centered-cubic (bcc) structures as it is compressed. Laser-driven experiments performed at the University of Rochester's Laboratory for Laser Energetics and the National Ignition Facility (NIF) ramp compressed Al samples to pressures up to 540 GPa without melting. Nanosecond in-situ x-ray diffraction was used to directly measure the crystal structure at pressures where the solid-solid phase transformations of Al are predicted to occur. Laser velocimetry provided the pressure in the Al. Our results show clear evidence of the fcc-hcp and hpc-bcc transformations at 216 +/- 9 GPa and 321 +/- 12 GPa, respectively. This is the first experimental in-situ observation of the bcc phase in compressed Al and a confirmation of the fcc-hcp transition previously observed under static compression at 217 GPa. The observations indicate these solid-solid phase transitions occur on the order of tens of nanoseconds time scales. In the fcc-hcp transition we find the original texture of the sample is preserved; however, the hcp-bcc transition diminishes that texture producing a structure that is more polycrystalline. The importance of this dynamic is discussed. The NIF results are the first demonstration of x-ray diffraction measurements at two different pressures in a single laser shot. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  18. Phase-Field Crystal Modeling of Polcrystalline Pattern Evolution in Hard and Soft Matter (United States)

    Karma, Alain


    The phase-field crystal (PFC) model has attracted considerable attention during the past decade for its potential application to model the complex defect-mediated dynamics of hard and soft crystalline materials on diffusive time scales. The model is rooted in earlier models of non-equilibrium pattern formation (Swift-Hohenberg equation), and classical density functional theory that expresses the free-energy of a system as a functional of its density. This talk will discuss progress made to investigate the dynamics for both isolated grain boundaries and complex polycrystalline patterns under the driving forces of boundary curvature and applied stress. The results highlight fundamental differences between polycrystalline pattern evolution in soft matter, including colloid crystals and crystalline non-equilibrium patterns described by the standard PFC dynamics, and crystalline solids described by a reformulation of this dynamics presented in this talk. The results also pave the way for a unified theory of polycrystalline pattern evolution in hard and soft matter.

  19. Crystal structure of the monoclinic phase (phase IV of bis(tetramethylammonium tetrachloridocuprate(II

    Directory of Open Access Journals (Sweden)

    Gorgui Awa Seck


    Full Text Available The crystal structure of the low-temperature monoclinic phase of the title compound, [(CH34N]2[CuCl4], was determined at 120 K. The structure of the room-temperature phase has been determined in the orthorhombic space group Pmcm [Morosin & Lingafelter (1961. J. Phys. Chem. 50–51; Clay et al. (1975. Acta Cryst. B31 289–290]. The asymmetric unit consists of one discrete tetrachloridocuprate anion with a distorted tetrahedral geometry and two tetramethylammonium cations. In the crystal, the cations and the anions are linked via weak C—H...Cl hydrogen bonds.

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

    DEFF Research Database (Denmark)

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


    In this study enzymatic-interesterified margarine fats with different conversion degrees were produced in a packed-bed reactor. The effects of conversion degree on the formation of free fatty acids and diacyglycerols, solid fat content, crystallization behavior, microstructure, and crystal network...... were investigated, and the enzymatically interesterified products were compared with a chemically interesterified product. Formation of free fatty acids and diacyglycerols increased slightly with increasing conversion degree. The solid fat content was higher at 10 and 20 °C and lower at 30, 35, and 40...... °C with increasing conversion degree. Increased conversion degree from the blend to products, measured by X-ray with addition of 50% of rapeseed oil for dilution, caused the content of â to decrease from 100% to 33%, and 30% and eventually to pure ⢠crystal. However, double chain packing...

  1. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase. (United States)

    Ericson, Daniel L; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M; Soares, Alexei S


    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals. © 2015 Society for Laboratory Automation and Screening.

  2. Acoustic Methods to Monitor Protein Crystallization and to Detect Protein Crystals in Suspensions of Agarose and Lipidic Cubic Phase

    Energy Technology Data Exchange (ETDEWEB)

    Ericson, Daniel L.; Yin, Xingyu; Scalia, Alexander; Samara, Yasmin N.; Stearns, Richard; Vlahos, Harry; Ellson, Richard; Sweet, Robert M.; Soares, Alexei S.


    Improvements needed for automated crystallography include crystal detection and crystal harvesting. A technique that uses acoustic droplet ejection to harvest crystals was previously reported. Here a method is described for using the same acoustic instrument to detect protein crystals and to monitor crystal growth. Acoustic pulses were used to monitor the progress of crystallization trials and to detect the presence and location of protein crystals. Crystals were detected, and crystallization was monitored in aqueous solutions and in lipidic cubic phase. Using a commercially available acoustic instrument, crystals measuring ~150 µm or larger were readily detected. Simple laboratory techniques were used to increase the sensitivity to 50 µm by suspending the crystals away from the plastic surface of the crystallization plate. This increased the sensitivity by separating the strong signal generated by the plate bottom that can mask the signal from small protein crystals. It is possible to further boost the acoustic reflection from small crystals by reducing the wavelength of the incident sound pulse, but our current instrumentation does not allow this option. In the future, commercially available sound-emitting transducers with a characteristic frequency near 300 MHz should detect and monitor the growth of individual 3 µm crystals.

  3. Exploring polymorphism in molecular crystals with a computational approach: phase transitions and energy landscapes

    NARCIS (Netherlands)

    Ende, J.A. van den


    Different crystal structures can possess different properties and therefore the control of polymorphism in molecular crystals is a goal in multiple industries, e.g. the pharmaceutical industry. Part I of this thesis is a computational study at the molecular scale of a particular solid-solid

  4. Tuning solid-state blue and red luminescence by the formation of solvate crystals. (United States)

    Yan, Dongpeng; Fan, Guoling; Guan, Yan; Meng, Qingyun; Li, Congju; Wang, Jiaona


    Tuning and controlling the solid-state luminescence of molecular solids play a key role in developing multi-color displays and tunable dye laser. In this work, we report the tunable blue and red luminescence by the formation of solvate crystals of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) and 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM). Upon introduction of guest solvents (chloroform and dichloromethane) into the POPOP and DCM host matrices, the obtained solvate crystals exhibit an alternated stacking arrangement, interaction fashion, and crystal symmetry compared with the pristine chromophore solids. Furthermore, the solvates of POPOP (CCl3H) and DCM (CCl2H2) present changeable luminescent properties (such as one-/two-photon emissive wavelength, fluorescence lifetime and photoluminescent quantum yield) in the blue/red regions relative to the pristine POPOP and DCM. In addition, the second harmonic generation can also be obtained for the DCM (CCl2H2) due to the transformation of the centrosymmetric to a non-centrosymmetric structure from pristine DCM. Periodic density functional theoretical calculations suggest that the guest solvents do not participate in the frontier orbital distribution within the solvate crystals. Therefore, by the combination of experimental and theoretical studies on the solvate crystals, this work not only reports the supramolecular assembly of new types of host-guest photoactive systems, but also provides a detailed understanding of the electronic structures of the solid-state luminescent materials.

  5. Pressure-induced reversible phase transition in thiourea dioxide crystal (United States)

    Wang, Qinglei; Yan, Tingting; Wang, Kai; Zhu, Hongyang; Cui, Qiliang; Zou, Bo


    The effect of high pressure on the crystal structure of thiourea dioxide has been investigated by Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell up to 10.3 GPa. The marked changes in the Raman spectra at 3.7 GPa strongly indicated a structural phase transition associated with the distortions of hydrogen bonding. There were no further changes up to the maximum pressure of 10.3 GPa and the observed transition was completely reversible when the system was brought back to ambient pressure. This transition was further confirmed by the changes of ADXRD spectra. The high-pressure phase was indexed and refined to an orthorhombic structure with a possible space group Pbam. The results from the first-principles calculations suggested that this phase transition was mainly related to the changes of hydrogen-bonded networks in thiourea dioxide.

  6. Pressure-induced reversible phase transition in thiourea dioxide crystal

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qinglei; Yan, Tingting; Zhu, Hongyang; Cui, Qiliang; Zou, Bo, E-mail:, E-mail: [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Wang, Kai, E-mail:, E-mail: [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); College of Chemistry, Jilin University, Changchun 130012 (China)


    The effect of high pressure on the crystal structure of thiourea dioxide has been investigated by Raman spectroscopy and angle-dispersive X-ray diffraction (ADXRD) in a diamond anvil cell up to 10.3 GPa. The marked changes in the Raman spectra at 3.7 GPa strongly indicated a structural phase transition associated with the distortions of hydrogen bonding. There were no further changes up to the maximum pressure of 10.3 GPa and the observed transition was completely reversible when the system was brought back to ambient pressure. This transition was further confirmed by the changes of ADXRD spectra. The high-pressure phase was indexed and refined to an orthorhombic structure with a possible space group Pbam. The results from the first-principles calculations suggested that this phase transition was mainly related to the changes of hydrogen-bonded networks in thiourea dioxide.

  7. Semi-automated microwave assisted solid-phase peptide synthesis

    DEFF Research Database (Denmark)

    Pedersen, Søren Ljungberg

    Biotage Initiator microwave instrument, which is available in many laboratories, with a modified semi-automated peptide synthesizer from MultiSynTech. A custom-made reaction vessel is placed permanently in the microwave oven, thus the reactor does not have to be moved between steps. Mixing is achieved...... with microwaves for SPPS has gained in popularity as it for many syntheses has provided significant improvement in terms of speed, purity, and yields, maybe especially in the synthesis of long and "difficult" peptides. Thus, precise microwave heating has emerged as one new parameter for SPPS, in addition...... to coupling reagents, resins, solvents etc. We have previously reported on microwave heating to promote a range of solid-phase reactions in SPPS. Here we present a new, flexible semi-automated instrument for the application of precise microwave heating in solid-phase synthesis. It combines a slightly modified...

  8. Combinatorial solid-phase synthesis of hapalosin mimetics

    DEFF Research Database (Denmark)

    Olsen, Jacob A.; Jensen, Knud J.; Nielsen, John


    The solid-phase synthesis of a small library of mimetics of the cyclic depsipeptide hapalosin is described. 3-Amino-4-hydroxy-5-nitrobenzoic acid was anchored through the anilino moiety to a backbone amide linker (BAL) handle support. Using chemoselective reactions and without the need for protec...... for protecting group manipulations, the benzoic acid group was first amidated, then the aniline nitrogen was acylated, and finally the nitro group was reduced to an amine and acylated or reductively alkylated, to generate a 12-member library.......The solid-phase synthesis of a small library of mimetics of the cyclic depsipeptide hapalosin is described. 3-Amino-4-hydroxy-5-nitrobenzoic acid was anchored through the anilino moiety to a backbone amide linker (BAL) handle support. Using chemoselective reactions and without the need...

  9. Studies in Solid Phase Peptide Synthesis: A Personal Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, A R


    By the early 1970s it had became apparent that the solid phase synthesis of ribonuclease A could not be generalized. Consequently, virtually every aspect of solid phase peptide synthesis (SPPS) was reexamined and improved during the decade of the 1970s. The sensitive detection and elimination of possible side reactions (amino acid insertion, N{sup {alpha}}-trifluoroacetylation, N{sup {alpha}{var_epsilon}}-alkylation) was examined. The quantitation of coupling efficiency in SPPS as a function of chain length was studied. A new and improved support for SPPS, the 'PAM-resin', was prepared and evaluated. These and many other studies from the Merrifield laboratory and elsewhere increased the general acceptance of SPPS leading to the 1984 Nobel Prize in Chemistry for Bruce Merrifield.

  10. All rights reserved Development of Headspace Solid-Phase ...

    African Journals Online (AJOL)


    fused silica DB5-MS column (30 m x 0.25 mm x. 0.25 µm i.d). The GC oven temperature program was as follows: 60 0C (2 min), ramped to 180 0C (0 min) at 30 0C/min, then ..... solid-phase microextraction fibers by sol-gel technology for the determination of organophosphorus pesticide multiresidues in food. J. Chromatogr.

  11. Solid-phase synthesis of oxetane modified peptides


    Beadle, Jonathan D.; Knuhtsen, Astrid; Hoose, Alex; Raubo, Piotr; Jamieson, Andrew G.; Shipman, Michael


    Solid-phase peptide synthesis (SPPS) is used to create peptidomimetics in which one of the backbone amide C=O bonds is replaced by a four-membered oxetane ring. The oxetane containing dipeptide building blocks are made in three steps in solution, then integrated into peptide chains by conventional Fmoc SPPS. This methodology is used to make a range of peptides in high purity including backbone modified derivatives of the nonapeptide bradykinin and Met- and Leu-enkephalin.\\ud

  12. Molecular dynamics and the phase transition in solid C60 (United States)

    Tycko, R.; Dabbagh, G.; Fleming, R. M.; Haddon, R. C.; Makhija, A. V.; Zahurak, S. M.


    The molecular reorientational dynamics in two phases of solid C60 with C-13 NMR measurements are characterized. A change in the nature of the dynamics, indicated by a change in kinetic parameters extracted from spin-lattice relaxation data, occurs at the phase transition at 260 K. Above the transition, the molecules appear to execute continuous rotational diffusion; below the transition, they appear to jump between symmetry-equivalent orientations. This interpretation is consistent with the X-ray-diffraction results of Heiney et al. (1991) as well as the NMR relaxation and spectral data.

  13. A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism (United States)

    Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei


    We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

  14. Solid-state NMR and computational insights into the crystal structure of silicocarnotite-based bioceramic materials synthesized mechanochemically. (United States)

    Andreev, A S; Bulina, N V; Chaikina, M V; Prosanov, I Yu; Terskikh, V V; Lapina, O B

    In this work, we report the results of a detailed structural study of a promising bioceramic material silicocarnotite Ca5(PO4)2SiO4 (SC) synthesized from mechanochemically treated nanosized silicon-substituted hydroxyapatite by annealing at 1000°C. This novel synthetic approach represents an attractive and efficient route towards large-scale manufacturing of the silicocarnotite-based bioceramics. A combination of solid-state nuclear magnetic resonance (NMR), powder X-ray crystallography and density function theory (DFT) calculations has been implemented to characterize the phase composition of the prepared composite materials and to gain insight into the crystal structure of silicocarnotite. The phase composition analysis based on the multinuclear solid-state NMR has been found in agreement with X-ray powder diffraction indicating the minority phases of CaO (5-6wt%) and residual silicon-apatite (7-8wt%), while the rest of the material being a fairly crystalline silicocarnotite phase (86-88wt%). A combination of computational (CASTEP) and experimental methods was used to address the anionic site disorder in the silicocarnotite crystal structure. Distorted [OPO3] pyramids have appeared as an important structural motif in the SC crystal structure. The ratio between regular [PO4] and distorted [OPO3] tetrahedra is found between 2:1 and 3:1 based on XRD experiments and CASTEP calculations. The natural abundance (43)Ca magic angle spinning NMR spectra of silicocarnotite are reported for the first time. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Structural disorder and transformation in crystal growth: direct observation of ring-opening isomerization in a metal–organic solid solution

    Directory of Open Access Journals (Sweden)

    Ji-Jun Jiang


    Full Text Available A rare example is reported in which discrete Ag2L2 ring and (AgL∞ chain motifs [L = N,N′-bis(3-imidazol-1-yl-propyl-pyromellitic diimide] co-crystallize in the same crystal lattice with varying ratios and degrees of disorder. Crystal structures obtained from representative crystals reveal compatible packing arrangements of the cyclic and polymeric isomers within the crystal lattice, which enables them to co-exist within a crystalline solid solution. A feasible pathway for transformation between the isomers is suggested via facile rotation of the coordinating imidazolyl groups. This chemical system could provide a chance for direct observation of ring-opening isomerization at the crystal surface. Mass spectrometry and 1H NMR titration show a dynamic equilibrium between cyclic and oligomeric species in solution, and a potential crystallization process is suggested involving alignment of precursors directed by aromatic stacking interactions between pyromellitic diimide units, followed by ring-opening isomerization at the interface between the solid and the solution. Both cyclic and oligomeric species can act as precursors, with interconversion between them being facile due to a low energy barrier for rotation of the imidazole rings. Thermogravimetric analysis and variable-temperature powder X-ray diffraction indicate a transition to a different crystalline phase around 120°C, which is associated with loss of solvent from the crystal lattice.

  16. Preparative crystallization of a single chain antibody using an aqueous two-phase system. (United States)

    Huettmann, Hauke; Berkemeyer, Matthias; Buchinger, Wolfgang; Jungbauer, Alois


    A simultaneous crystallization and aqueous two-phase extraction of a single chain antibody was developed, demonstrating process integration. The process conditions were designed to form an aqueous two-phase system, and to favor crystallization, using sodium sulfate and PEG-2000. At sufficiently high concentrations of PEG, a second phase was generated in which the protein crystallization occurred simultaneously. The single chain antibody crystals were partitioned to the top, polyethylene glycol-rich phase. The crystal nucleation took place in the sodium sulfate-rich phase and at the phase boundary, whereas crystal growth was progressing mainly in the polyethylene glycol-rich phase. The crystals in the polyethylene glycol-rich phase grew to a size of >50 µm. Additionally, polyethylene glycol acted as an anti-solvent, thus, it influenced the crystallization yield. A phase diagram with an undersaturation zone, crystallization area, and amorphous precipitation zone was established. Only small differences in polyethylene glycol concentration caused significant shifts of the crystallization yield. An increase of the polyethylene glycol content from 2% (w/v) to 4% (w/v) increased the yield from approximately 63-87%, respectively. Our results show that crystallization in aqueous two-phase systems is an opportunity to foster process integration. © 2014 Wiley Periodicals, Inc.

  17. Plasticity and dislocation dynamics in a phase field crystal model. (United States)

    Chan, Pak Yuen; Tsekenis, Georgios; Dantzig, Jonathan; Dahmen, Karin A; Goldenfeld, Nigel


    The critical dynamics of dislocation avalanches in plastic flow is examined using a phase field crystal model. In the model, dislocations are naturally created, without any ad hoc creation rules, by applying a shearing force to the perfectly periodic ground state. These dislocations diffuse, interact and annihilate with one another, forming avalanche events. By data collapsing the event energy probability density function for different shearing rates, a connection to interface depinning dynamics is confirmed. The relevant critical exponents agree with mean field theory predictions.

  18. Polarization effects on the electric properties of urea and thiourea molecules in solid phase (United States)

    Santos, O. L.; Fonseca, T. L.; Sabino, J. R.; Georg, H. C.; Castro, M. A.


    We present theoretical results for the dipole moment, linear polarizability, and first hyperpolarizability of the urea and thiourea molecules in solid phase. The in-crystal electric properties were determined by applying a supermolecule approach in combination with an iterative electrostatic scheme, in which the surrounding molecules are represented by point charges. It is found for both urea and thiourea molecules that the influence of the polarization effects is mild for the linear polarizability, but it is marked for the dipole moment and first hyperpolarizability. The replacement of oxygen atoms by sulfur atoms increases, in general, the electric responses. Our second-order Møller-Plesset perturbation theory based iterative scheme predicts for the in-crystal dipole moment of urea and thiourea the values of 7.54 and 9.19 D which are, respectively, increased by 61% and 58%, in comparison with the corresponding isolated values. The result for urea is in agreement with the available experimental result of 6.56 D. In addition, we present an estimate of macroscopic quantities considering explicit unit cells of urea and thiourea crystals including environment polarization effects. These supermolecule calculations take into account partially the exchange and dispersion effects. The results illustrate the role played by the electrostatic interactions on the static second-order nonlinear susceptibility of the urea crystal.

  19. Polarization effects on the electric properties of urea and thiourea molecules in solid phase

    Energy Technology Data Exchange (ETDEWEB)

    Santos, O. L.; Fonseca, T. L., E-mail:; Sabino, J. R.; Georg, H. C.; Castro, M. A. [Instituto de Física, Universidade Federal de Goiás, Campus Samambaia, 74.690-900 Goiânia, GO (Brazil)


    We present theoretical results for the dipole moment, linear polarizability, and first hyperpolarizability of the urea and thiourea molecules in solid phase. The in-crystal electric properties were determined by applying a supermolecule approach in combination with an iterative electrostatic scheme, in which the surrounding molecules are represented by point charges. It is found for both urea and thiourea molecules that the influence of the polarization effects is mild for the linear polarizability, but it is marked for the dipole moment and first hyperpolarizability. The replacement of oxygen atoms by sulfur atoms increases, in general, the electric responses. Our second-order Møller–Plesset perturbation theory based iterative scheme predicts for the in-crystal dipole moment of urea and thiourea the values of 7.54 and 9.19 D which are, respectively, increased by 61% and 58%, in comparison with the corresponding isolated values. The result for urea is in agreement with the available experimental result of 6.56 D. In addition, we present an estimate of macroscopic quantities considering explicit unit cells of urea and thiourea crystals including environment polarization effects. These supermolecule calculations take into account partially the exchange and dispersion effects. The results illustrate the role played by the electrostatic interactions on the static second-order nonlinear susceptibility of the urea crystal.

  20. Numerical study of light-induced phase behavior of smectic solids (United States)

    Chung, Hayoung; Park, Jaesung; Cho, Maenghyo


    By the chemical cross-linking of rigid molecules, liquid crystal polymer (LCP) has been envisaged as a novel heterogeneous material due to the fact that various optical and geometric states of the liquid crystalline (LC) phases are projected onto the polymeric constituents. The phase behavior, which refers to the macroscopic shape change of LCP under thermotropic phase change, is a compelling example of such optical-mechanical coupling. In this study, the photomechanical behavior, which broadly refers to the thermal- or light-induced actuation of smectic solids, is investigated using three-dimensional nonlinear finite element analysis (FEA). First, the various phases of LC are considered as well as their relation to polymeric conformation defined by the strain energy of the smectic polymer; a comprehensive constitutive equation that bridges the strong, optomechanical coupling is then derived. Such photomechanical coupling is incorporated in the FEA considering geometric nonlinearity, which is vital to understanding the large-scale light-induced bending behavior of the smectic solid.To demonstrate the simulation capability of the present model, numerous examples of photomechanical deformations are investigated parametrically, either by changing the operating conditions such as stimuli (postsynthesis) or the intrinsic properties (presynthesis). When compared to nematic solids, distinguished behaviors due to smectic substances are found herein and discussed through experiments. The quasisoftness that bidirectionally couples microscopic variables to mechanical behavior is also explained, while considering the effect of nonlinearity. In addition to providing a comprehensive measure that could deepen the knowledge of photomechanical coupling, the use of the proposed finite element framework offers an insight into the design of light-responsive actuating systems made of smectic solids.

  1. High-pressure high-temperature phase diagram of organic crystal paracetamol (United States)

    Smith, Spencer J.; Montgomery, Jeffrey M.; Vohra, Yogesh K.


    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped heating diamond anvil. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in five different experiments. Solid state phase transitions from monoclinic Form I  →  orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II  →  unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. This new data is combined with previous ambient temperature high-pressure Raman and x-ray diffraction data to create the first HPHT phase diagram of paracetamol.

  2. Extremely efficient crystallization of HKUST-1 and Keggin-loaded related phases through the epoxide route. (United States)

    Oestreicher, Víctor; Jobbágy, Matías


    Highly crystalline HKUST-1 and COK-16-like phases were obtained based on a mild in situ alkalinization one-pot epoxide driven method. A slurry composed of finely ground trimesic acid, H3BTC, dispersed in a CuCl2 aqueous solution quantitatively developed well crystallized HKUST-1 after the addition of propylene oxide. The use of solid H3BTC ensures a low concentration of free linker, favoring crystalline growth over the precipitation of amorphous or metastable impurities. An extreme space-time yield of 2.1 × 10(5) kg m(-3) day(-1) was reached, with no linker excess and minimum use of solvent. The method was equally efficient in the achievement of pure NENU/COK-16 phases, containing [PW12O40](3-), [PMo12O40](3-) and [SiMo12O40](4-) polyoxometalates.

  3. Intermittent dislocation density fluctuations in crystal plasticity from a phase-field crystal model

    DEFF Research Database (Denmark)

    Tarp, Jens M.; Angheluta, Luiza; Mathiesen, Joachim


    Plastic deformation mediated by collective dislocation dynamics is investigated in the two-dimensional phase-field crystal model of sheared single crystals. We find that intermittent fluctuations in the dislocation population number accompany bursts in the plastic strain-rate fluctuations....... Dislocation number fluctuations exhibit a power-law spectral density 1/f2 at high frequencies f. The probability distribution of number fluctuations becomes bimodal at low driving rates corresponding to a scenario where low density of defects alternates at irregular times with high populations of defects. We...... propose a simple stochastic model of dislocation reaction kinetics that is able to capture these statistical properties of the dislocation density fluctuations as a function of shear rate....

  4. Intermittent dislocation density fluctuations in crystal plasticity from a phase-field crystal model. (United States)

    Tarp, Jens M; Angheluta, Luiza; Mathiesen, Joachim; Goldenfeld, Nigel


    Plastic deformation mediated by collective dislocation dynamics is investigated in the two-dimensional phase-field crystal model of sheared single crystals. We find that intermittent fluctuations in the dislocation population number accompany bursts in the plastic strain-rate fluctuations. Dislocation number fluctuations exhibit a power-law spectral density 1/f2 at high frequencies f. The probability distribution of number fluctuations becomes bimodal at low driving rates corresponding to a scenario where low density of defects alternates at irregular times with high populations of defects. We propose a simple stochastic model of dislocation reaction kinetics that is able to capture these statistical properties of the dislocation density fluctuations as a function of shear rate.

  5. Theory of Solid-Liquid Interface and Crystal Growth (United States)

    Homma, Shigeo; Yoshida, Uichi; Nakano, Huzio


    The equilibrium properties of solid-liquid interface are investigated based on multi-level model (MLM) by Temkin. The simple expression is derived to the shape of the interface. The surface tension is obtained, giving rise to the lattice resistance to the motion of the interface. Simple kinetic theory for the propagation of the interface in nonequilibrium state is introduced. The propagating velocity of the interface is derived within linear approximation. The result is in agreement with that of the computer experiment qualitatively.

  6. Crystal-Structure Contribution to the Solid Solubility in Transition Metal Alloys

    DEFF Research Database (Denmark)

    Ruban, Andrei; Skriver, Hans Lomholt; Nørskov, Jens Kehlet


    The solution energies of 4d metals in other 4d metals as well as the bcc-hcp structural energy differences in random 4d alloys are calculated by density functional theory. It is shown that the crystal structure of the host plays a crucial role in the solid solubility. A local virtual bond...

  7. Recent advances in secondary ion mass spectrometry of solid acid catalysts : Large zeolite crystals under bombardment

    NARCIS (Netherlands)

    Hofmann, Jan P.; Rohnke, Marcus; Weckhuysen, Bert M.


    This Perspective aims to inform the heterogeneous catalysis and materials science community about the recent advances in Time-of-Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) to characterize catalytic solids by taking large model H-ZSM-5 zeolite crystals as a showcase system. SIMS-based

  8. Influence of pH and method of crystallization on the solid physical form of indomethacin. (United States)

    Dubbini, Alessandra; Censi, Roberta; Martena, Valentina; Hoti, Ela; Ricciutelli, Massimo; Malaj, Ledjan; Di Martino, Piera


    The purpose of this study was to investigate the effect of pH and method of crystallization on the solid physical form of indomethacin (IDM). IDM, a non steroidal anti-inflammatory drug poorly soluble in water, underwent two different crystallization methods: crystallization by solvent evaporation under reduced pressure at 50.0°C (method A), and crystallization by cooling of solution from 50.0 to 5.0°C (method B). In both cases, several aqueous ethanolic solutions of IDM of different pHs were prepared. pHs were adjusted by adding acidic solutions (HCl 2M) or alkali (NaOH or NH4OH 2M) to an aqueous ethanolic solution of IDM. Thus, several batches were recovered after crystallization. The chemical stability of IDM was verified through (1)H NMR and mass spectroscopy (FIA-ESI-MS), that revealed that IDM degraded in strong alkali media (pH ≥ 12). Crystals obtained under different crystallization conditions at pHs of 1.0, 4.5, 7.0, 8.0, 10.0 and chemically stable were thus characterized for crystal habit by scanning electron microscopy, for thermal behaviour by differential scanning calorimetry, and thermogravimetry, and for solid state by X-ray powder diffractometry. Under the Method A, IDM always crystallized into pure metastable alpha form when solutions were acidified or alkalized respectively with HCl and NH4OH. On the contrary, in presence of NaOH, IDM crystallized under a mixture of alpha and sodium trihydrate form, because the presence of the sodium counter ion orientates the crystallization towards the formation of the trihydrate salt. Under the method B, at pH of 1.0, IDM crystallized under the alpha form; at pH 4.5, IDM crystallized under the form alpha in presence of some nuclei of gamma form; at pH 7.0, 8.0, and 10.0 for NH4OH, IDM crystallized under the most stable polymorph gamma form, whereas in presence of NaOH, a mix of alpha, and salt forms was formed whatever the pH of the solution. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Thermodynamic phase behavior of API/polymer solid dispersions. (United States)

    Prudic, Anke; Ji, Yuanhui; Sadowski, Gabriele


    To improve the bioavailability of poorly soluble active pharmaceutical ingredients (APIs), these materials are often integrated into a polymer matrix that acts as a carrier. The resulting mixture is called a solid dispersion. In this work, the phase behaviors of solid dispersions were investigated as a function of the API as well as of the type and molecular weight of the carrier polymer. Specifically, the solubility of artemisinin and indomethacin was measured in different poly(ethylene glycol)s (PEG 400, PEG 6000, and PEG 35000). The measured solubility data and the solubility of sulfonamides in poly(vinylpyrrolidone) (PVP) K10 and PEG 35000 were modeled using the perturbed-chain statistical associating fluid theory (PC-SAFT). The results show that PC-SAFT predictions are in a good accordance with the experimental data, and PC-SAFT can be used to predict the whole phase diagram of an API/polymer solid dispersion as a function of the kind of API and polymer and of the polymer's molecular weight. This remarkably simplifies the screening process for suitable API/polymer combinations.

  10. Encoding Gaussian curvature in glassy and elastomeric liquid crystal solids (United States)

    Mostajeran, Cyrus; Warner, Mark; Ware, Taylor H.; White, Timothy J.


    We describe shape transitions of thin, solid nematic sheets with smooth, preprogrammed, in-plane director fields patterned across the surface causing spatially inhomogeneous local deformations. A metric description of the local deformations is used to study the intrinsic geometry of the resulting surfaces upon exposure to stimuli such as light and heat. We highlight specific patterns that encode constant Gaussian curvature of prescribed sign and magnitude. We present the first experimental results for such programmed solids, and they qualitatively support theory for both positive and negative Gaussian curvature morphing from flat sheets on stimulation by light or heat. We review logarithmic spiral patterns that generate cone/anti-cone surfaces, and introduce spiral director fields that encode non-localized positive and negative Gaussian curvature on punctured discs, including spherical caps and spherical spindles. Conditions are derived where these cap-like, photomechanically responsive regions can be anchored in inert substrates by designing solutions that ensure compatibility with the geometric constraints imposed by the surrounding media. This integration of such materials is a precondition for their exploitation in new devices. Finally, we consider the radial extension of such director fields to larger sheets using nematic textures defined on annular domains.

  11. Optical Activity in Twisted Solid-Core Photonic Crystal Fibers (United States)

    Xi, X. M.; Weiss, T.; Wong, G. K. L.; Biancalana, F.; Barnett, S. M.; Padgett, M. J.; St. J. Russell, P.


    In this Letter we show that, in spectral regions where there are no orbital cladding resonances to cause transmission loss, the core mode of a continuously twisted photonic crystal fiber (PCF) exhibits optical activity, and that the magnitude of the associated circular birefringence increases linearly with twist rate and is highly reproducible. In contrast to previous work on twist-induced circular birefringence, PCF has zero linear birefringence and an on-axis core, making the appearance of circular birefringence rather unexpected. A theoretical model based on symmetry properties and perturbation theory is developed and used to show that both spin and orbital angular momentum play a role in this effect. It turns out that the degenerate left- and right-circularly polarized modes of the untwisted PCF are not 100% circularly polarized but carry a small amount of orbital angular momentum caused by the interaction between the core mode and the hollow channels.

  12. Quantum Chemistry of Solids The LCAO First Principles Treatment of Crystals

    CERN Document Server

    Evarestov, Robert A


    Quantum Chemistry of Solids delivers a comprehensive account of the main features and possibilities of LCAO methods for the first principles calculations of electronic structure of periodic systems. The first part describes the basic theory underlying the LCAO methods applied to periodic systems and the use of wave-function-based (Hartree-Fock), density-based (DFT) and hybrid hamiltonians. The translation and site symmetry consideration is included to establish connection between k-space solid-state physics and real-space quantum chemistry methods in the framework of cyclic model of an infinite crystal. The inclusion of electron correlation effects for periodic systems is considered on the basis of localized crystalline orbitals. The possibilities of LCAO methods for chemical bonding analysis in periodic systems are discussed. The second part deals with the applications of LCAO methods for calculations of bulk crystal properties, including magnetic ordering and crystal structure optimization. The discussion o...

  13. Stabilizing blue phase liquid crystals with linearly polarized UV light (United States)

    Xu, Daming; Yuan, Jiamin; Schadt, Martin; Yan, Jing; Wu, Shin-Tson


    Polymer-stabilized blue-phase liquid crystal (PS-BPLC) has become an increasingly important technology trend for information display and photonic applications. BPLC exhibits several attractive features, such as reasonably wide temperature range, submillisecond gray-to-gray response time, no need for alignment layer, optically isotropic voltageoff state, and large cell gap tolerance when an in-plane switching (IPS) cell is employed. However, some bottlenecks such as high operation voltage, relatively low transmittance, and noticeable hysteresis and prolonged response time at high field region for IPS mode, still remain to be overcome before widespread application of BPLC can be realized. To reduce operation voltage, both new BPLC materials and new device structures have been investigated. In this paper, we demonstrate the stabilization a photopolymer-embedded blue phase liquid crystal precursor using a linearly polarized UV light for first time. When the UV polarization axis is perpendicular to the stripe electrodes of an IPS cell, anisotropic polymer networks are formed through the linear photo-polymerization process and the electrostriction effect is suppressed. As a result, the measured hysteresis is dramatically reduced from 6.95% to 0.36% and the response time shortened by ~2X compared to unpolarized UV exposure. To induce larger anisotropy in polymer networks for mitigating the electrostriction effect, high-intensity linearly polarized UV exposure is preferred. It is foreseeable this method will guide future BPLC device and material development as well as manufacturing process. The dawn of BPLCD is near.

  14. Heat transfer in different phases of solid cyclohexene

    Energy Technology Data Exchange (ETDEWEB)

    Konstantinov, V.A., E-mail:; Krivchikov, A.I.; Korolyuk, O.A.; Revyakin, V.P.; Sagan, V.V.; Vdovichenko, G.A.; Zvonaryova, A.V.


    The thermal conductivity of solid cyclohexene C{sub 6}H{sub 10} has been measured in two independent experiments in five different stable and metastable phase states: orientational glass (Ig), orientational glass (IIIg) with a partial order, dynamically orientationally disordered state (III) with a partial order, completely orientationally ordered phase (II) and “plastic” phase (I). The measurements were carried out at saturated vapor pressure in the temperature range 2–120 K and at isochoric conditions in “plastic” and orientationally ordered phases on samples of different densities. The isochoric thermal conductivity of “plastic” phase increases smoothly with temperature. It can be attributed to weakening of the translational orientational coupling which, in turn, leads to a decrease in phonon scattering on rotational excitations. The thermal conductivity of cyclohexene measured at saturated vapor pressure exhibits a similar behavior in phases Ig, IIIg, and II. At low temperatures (T<8 K) the thermal conductivity tends to T{sup 2} dependence{sup ,} passes through a maximum and decreases further with increasing temperature following the dependence, which is somewhat different from 1/T. It was found that the thermal conductivity can be represented as a sum of two contributions κ(T)=κ{sub 1}(T)+κ{sub 2}(T), where κ{sub 1}(T) is due to propagating phonons whose mean-free path exceeds half the phonon wavelength, and κ{sub 2}(T) is attributed to localized short-wavelength or “diffusive” vibrational modes.

  15. Ultrafast characterization of phase-change material crystallization properties in the melt-quenched amorphous phase. (United States)

    Jeyasingh, Rakesh; Fong, Scott W; Lee, Jaeho; Li, Zijian; Chang, Kuo-Wei; Mantegazza, Davide; Asheghi, Mehdi; Goodson, Kenneth E; Wong, H-S Philip


    Phase change materials are widely considered for application in nonvolatile memories because of their ability to achieve phase transformation in the nanosecond time scale. However, the knowledge of fast crystallization dynamics in these materials is limited because of the lack of fast and accurate temperature control methods. In this work, we have developed an experimental methodology that enables ultrafast characterization of phase-change dynamics on a more technologically relevant melt-quenched amorphous phase using practical device structures. We have extracted the crystallization growth velocity (U) in a functional capped phase change memory (PCM) device over 8 orders of magnitude (10(-10) 10(8) K/s), which reveals the extreme fragility of Ge2Sb2Te5 in its supercooled liquid phase. Furthermore, these crystallization properties were studied as a function of device programming cycles, and the results show degradation in the cell retention properties due to elemental segregation. The above experiments are enabled by the use of an on-chip fast heater and thermometer called as microthermal stage (MTS) integrated with a vertical phase change memory (PCM) cell. The temperature at the PCM layer can be controlled up to 600 K using MTS and with a thermal time constant of 800 ns, leading to heating rates ∼10(8) K/s that are close to the typical device operating conditions during PCM programming. The MTS allows us to independently control the electrical and thermal aspects of phase transformation (inseparable in a conventional PCM cell) and extract the temperature dependence of key material properties in real PCM devices.

  16. High-Pressure High-Temperature Phase Diagram of the Organic Crystal Paracetamol (United States)

    Smith, Spencer; Montgomery, Jeffrey; Vohra, Yogesh

    High-pressure high-temperature (HPHT) Raman spectroscopy studies have been performed on the organic crystal paracetamol in a diamond anvil cell utilizing boron-doped diamond as heating anvil. The HPHT data obtained from boron-doped diamond heater is cross-checked with data obtained using a standard block heater diamond anvil cell. Isobaric measurements were conducted at pressures up to 8.5 GPa and temperature up to 520 K in a number of different experiments. Solid state phase transitions from monoclinic Form I --> orthorhombic Form II were observed at various pressures and temperatures as well as transitions from Form II --> unknown Form IV. The melting temperature for paracetamol was observed to increase with increasing pressures to 8.5 GPa. Our previous angle dispersive x-ray diffraction studies at the Advanced Photon Source has confirmed the existence of two unknown crystal structures Form IV and Form V of paracetamol at high pressure and ambient temperature. The phase transformation from Form II to Form IV occurs at ~8.5 GPa and from Form IV to Form V occurs at ~11 GPa at ambient temperature. Our new data is combined with the previous ambient temperature high-pressure Raman and X- ray diffraction data to create the first HPHT phase diagram of paracetamol. Doe-NNSA Carnegie DOE Alliance Center (CDAC) under Grant Number DE-NA0002006.

  17. Novel solidsolid phase change material based on polyethylene glycol and cellulose used for temperature stabilisation

    Directory of Open Access Journals (Sweden)

    Wojda Marta


    Full Text Available Thermal management is one of crucial issues in the development of modern electronic devices. In the recent years interest in phase change materials (PCMs as alternative cooling possibility has increased significantly. Preliminary results concerning the research into possibility of the use of solid-solid phase change materials (S-S PCMs for stabilisation temperature of electronic devices has been presented in the paper. Novel solid-solid phase change material based on polyethylene glycol and cellulose has been synthesized. Attempt to improve its thermal conductivity has been taken. Material has been synthesized for the purpose of stabilisation of temperature of electronic devices.

  18. Experimental setup for the growth of solid crystals of inert gases for particle detection (United States)

    Guarise, M.; Braggio, C.; Calabrese, R.; Carugno, G.; Dainelli, A.; Khanbekyan, A.; Luppi, E.; Mariotti, E.; Poggi, M.; Tomassetti, L.


    Low energy threshold detectors are necessary in many frontier fields of the experimental physics. In this work, we present a novel detection approach based on pure or doped matrices of inert gases solidified at cryogenic temperatures. The small energy release of the incident particle can be transferred directly (in pure crystals) or through a laser-driven ionization (in doped materials) to the electrons of the medium that are then converted into free electrons. The charge collection process of the electrons that consists in their drift within the crystal and their extraction through the solid-vacuum interface gives rise to an electric signal that we exploit for preliminary tests of charge collection and crystal quality. Such tests are carried out in different matrices of neon and methane using an UV-assisted apparatus for electron injection in crystals.

  19. Solid-state NMR studies of theophylline co-crystals with dicarboxylic acids. (United States)

    Pindelska, Edyta; Sokal, Agnieszka; Szeleszczuk, Lukasz; Pisklak, Dariusz Maciej; Kolodziejski, Waclaw


    In this work, three polycrystalline materials containing co-crystals of theophylline with malonic, maleic, and glutaric acids were studied using (13)C, (15)N and (1)H solid-state NMR and FT-IR spectroscopy. The NMR assignments were supported by gauge including projector augmented waves (GIPAW) calculations of chemical shielding, performed using X-ray determined geometry. The experimental (13)C cross polarization/magic angle spinning (CP/MAS) NMR results and the calculated isotropic chemical shifts were in excellent agreement. A rapid and convenient method for theophylline co-crystals crystal structure analysis has been proposed for co-crystals, which are potentially new APIs. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Sensitive and fast mutation detection by solid phase chemical cleavage

    DEFF Research Database (Denmark)

    Hansen, Lise Lotte; Justesen, Just; Kruse, Torben A


    We have developed a solid phase chemical cleavage method (SpCCM) for screening large DNA fragments for mutations. All reactions can be carried out in microtiterwells from the first amplification of the patient (or test) DNA through the search for mutations. The reaction time is significantly...... reduced compared to the conventional chemical cleavage method (CCM), and even by using a uniformly labelled probe, the exact position and nature of the mutation can be revealed. The SpCCM is suitable for automatization using a workstation to carry out the reactions and a fluorescent detection-based DNA...

  1. Solid-phase synthesis of cecropin A and related peptides. (United States)

    Andreu, D; Merrifield, R B; Steiner, H; Boman, H G


    Cecropin A, a 37-residue antibacterial peptide amide, was synthesized by the solid-phase method. It was shown to be homogeneous and totally indistinguishable from natural cecropin A by chemical and physical criteria, as well as by its antibacterial activity against several Gram-positive and Gram-negative organisms. The synthetic material was also used to establish unambiguously that the carboxyl-terminal blocking group of natural cecropin A is a primary amide as tentatively proposed earlier. The role of the amino terminus of cecropin A in antibacterial activity was investigated by the synthesis of two analogs. Images PMID:6579533

  2. Advances in solid-phase extraction disks for environmental chemistry (United States)

    Thurman, E.M.; Snavely, K.


    The development of solid-phase extraction (SPE) for environmental chemistry has progressed significantly over the last decade to include a number of new sorbents and new approaches to SPE. One SPE approach in particular, the SPE disk, has greatly reduced or eliminated the use of chlorinated solvents for the analysis of trace organic compounds. This article discusses the use and applicability of various SPE disks, including micro-sized disks, prior to gas chromatography-mass spectrometry for the analysis of trace organic compounds in water. Copyright (C) 2000 Elsevier Science B.V.

  3. Solid phase microextraction fills the gap in tissue sampling protocols. (United States)

    Bojko, Barbara; Gorynski, Krzysztof; Gomez-Rios, German Augusto; Knaak, Jan Matthias; Machuca, Tiago; Spetzler, Vinzent Nikolaus; Cudjoe, Erasmus; Hsin, Michael; Cypel, Marcelo; Selzner, Markus; Liu, Mingyao; Keshavjee, Shaf; Pawliszyn, Janusz


    Metabolomics and biomarkers discovery are an integral part of bioanalysis. However, untargeted tissue analysis remains as the bottleneck of such studies due to the invasiveness of sample collection, as well as the laborious and time-consuming sample preparation protocols. In the current study, technology integrating in vivo sampling, sample preparation and global extraction of metabolites--solid phase microextraction was presented and evaluated during liver and lung transplantation in pig model. Sampling approaches, including selection of the probe, transportation, storage conditions and analyte coverage were discussed. The applicability of the method for metabolomics studies was demonstrated during lung transplantation experiments. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Crystallization process (United States)

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey


    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  5. Powder metallurgy: Solid and liquid phase sintering of copper (United States)

    Sheldon, Rex; Weiser, Martin W.


    Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

  6. Unusual seeding mechanism for enhanced performance in solid-phase magnetic extraction of Rare Earth Elements. (United States)

    Polido Legaria, Elizabeth; Rocha, Joao; Tai, Cheuk-Wai; Kessler, Vadim G; Seisenbaeva, Gulaim A


    Due to the increasing demand of Rare Earth Elements (REE or RE), new and more efficient techniques for their extraction are necessary, suitable for both mining and recycling processes. Current techniques such as solvent extraction or solid adsorbents entail drawbacks such as using big volumes of harmful solvents or limited capacity. Hybrid nanoadsorbents based on SiO 2 and highly stable γ-Fe 2 O 3 -SiO 2 nanoparticles, proved recently to be very attractive for adsorption of REE, yet not being the absolute key to solve the problem. In the present work, we introduce a highly appealing new approach in which the nanoparticles, rather than behaving as adsorbent materials, perform as inducers of crystallization for the REE in the form of hydroxides, allowing their facile and practically total removal from solution. This induced crystallization is achieved by tuning the pH, offering an uptake efficiency more than 20 times higher than previously reported (up to 900 mg RE 3+ /g vs. 40 mg RE 3+ /g). The obtained phases were characterized by SEM-EDS, TEM, STEM and EFTEM and 13 C and 29 Si solid state NMR. Magnetic studies showed that the materials possessed enough magnetic properties to be easily removed by a magnet, opening ways for an efficient and industrially applicable separation technique.

  7. Crystal structure study and investigation of solid-state cyclization for AMG 222, a channel hydrate. (United States)

    Kiang, Y-H; Nagapudi, Karthik; Liu, Jodi; Staples, Richard J; Jona, Janan


    In this study, we investigate the solid-state structure and stability of AMG 222 (5-(2-[2-(2-cyano-pyrrolidin-1-yl)-2-oxo-ethylamino]-propyl)-5-(1H-tetrazol-5-yl)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene-2,8 dicarboxylic acid bisdimethylamide), a small molecule DPP-IV inhibitor. Crystal structure of AMG 222 has been solved from single crystal X-ray analysis. Crystallographic data are as follows: monoclinic, P2(1) (no. 4), a=9.0327(5)Å, b=18.6177(8)Å, c=21.4927(10)Å, β=90.126(3)°, V=3614.4(3)Å(3), Z=4. Based on single crystal structure, AMG 222 is a pentahydrate with the water molecules sitting in channels formed by the drug framework. There are three distinct crystal structures of AMG 222 between 0 and 95% relative humidity (RH), namely the anhydrate, hemihydrate, and pentahydrate forms. Solid-state stability of the GMP batch showed a high level of cyclized degradation product. It was postulated that the degradation was promoted by increased amorphous content generated as a result of excessive drying that was employed to remove residual crystallization solvent. Material produced using a modified procedure using a humidified nitrogen purge had lower amorphous content and lower levels of cyclic degradation when compared to the GMP batch. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Solid-solid phase transformation via internal stress-induced virtual melting: Additional confirmations (United States)

    Levitas, Valery I.; Smilowitz, Laura B.; Henson, Bryan F.; Asay, Blaine W.


    Recently, we predicted a mechanism of solid-solid phase transformation (PT) via virtual melting at 121K below the melting temperature. We report additional experimental and theoretical results for PTs among three polymorphs of the energetic material HMX, α, β, and δ that support this mechanism. In particular: (a) the predicted velocity of interface propagation for β →δ PT and overall kinetics of δ →β PT are in agreement with experiment; (b) the energy of internal stresses is sufficient to reduce the melting temperature from 520to400K for δ →β PT; (c) the nanocracking that appears during solidification does not change the PT thermodynamics and kinetics for the first and the second β ↔δ PT cycles; (d) δ →β PT starts at a very small driving force; (e) δ →α and α →δ PTs do not occur above 400K and below 461K, respectively.

  9. Solid-phase extraction of perfluoroalkylated compounds from sea water. (United States)

    Villaverde-de-Sáa, Eugenia; Fernández-López, María; Rodil, Rosario; Quintana, José Benito; Racamonde, Inés; Cela, Rafael


    This study describes an in-depth investigation of the parameters involved in the solid-phase extraction performance of perfluoroalkylated compounds (seven carboxylates and one sulfonate), particularly with sea water samples. The two most popular sorbents, Oasis WAX and Oasis HLB, were considered and it was observed that the high ionic strength of sea water may impair solid-phase extraction recoveries. In the final protocol, Oasis HLB cartridges were selected, incorporating a 10% methanol clean-up step before elution with methanol, since less matrix effects were obtained. The proposed method allows successful recoveries, higher than 71%, and relative standard deviations lower than 20%. It also provides excellent limits of detection values between 0.01 and 0.21 ng/L. Finally, the method was applied to fresh and sea water samples, where several perfluoroalkylated compounds were found at concentrations ranging between 0.16 and 64 ng/L. In the case of perfluorooctane sulfonate, recently included in the Water Frame Directive, its concentration reached the highest values among the perfluoroalkylated compounds measured (64 ng/L in river samples). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Phase-field-crystal models and mechanical equilibrium. (United States)

    Heinonen, V; Achim, C V; Elder, K R; Buyukdagli, S; Ala-Nissila, T


    Phase-field-crystal (PFC) models constitute a field theoretical approach to solidification, melting, and related phenomena at atomic length and diffusive time scales. One of the advantages of these models is that they naturally contain elastic excitations associated with strain in crystalline bodies. However, instabilities that are diffusively driven towards equilibrium are often orders of magnitude slower than the dynamics of the elastic excitations, and are thus not included in the standard PFC model dynamics. We derive a method to isolate the time evolution of the elastic excitations from the diffusive dynamics in the PFC approach and set up a two-stage process, in which elastic excitations are equilibrated separately. This ensures mechanical equilibrium at all times. We show concrete examples demonstrating the necessity of the separation of the elastic and diffusive time scales. In the small-deformation limit this approach is shown to agree with the theory of linear elasticity.

  11. Studies of phase transitions in the aripiprazole solid dosage form. (United States)

    Łaszcz, Marta; Witkowska, Anna


    Studies of the phase transitions in an active substance contained in a solid dosage form are very complicated but essential, especially if an active substance is classified as a BCS Class IV drug. The purpose of this work was the development of sensitive methods for the detection of the phase transitions in the aripiprazole tablets containing initially its form III. Aripiprazole exhibits polymorphism and pseudopolymorphism. Powder diffraction, Raman spectroscopy and differential scanning calorimetry methods were developed for the detection of the polymorphic transition between forms III and I as well as the phase transition of form III into aripiprazole monohydrate in tablets. The study involved the initial 10 mg and 30 mg tablets, as well as those stored in Al/Al blisters, a triplex blister pack and HDPE bottles (with and without desiccant) under accelerated and long term conditions. The polymorphic transition was not observed in the initial and stored tablets but it was visible on the DSC curve of the Abilify(®) 10 mg reference tablets. The formation of the monohydrate was observed in the diffractograms and Raman spectra in the tablets stored under accelerated conditions. The monohydrate phase was not detected in the tablets stored in the Al/Al blisters under long term conditions. The results showed that the Al/Al blisters can be recommended as the packaging of the aripiprazole tablets containing form III. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Dynamics of mineral crystallization from precipitated slab-derived fluid phase: first in situ synchrotron X-ray measurements (United States)

    Malaspina, Nadia; Alvaro, Matteo; Campione, Marcello; Wilhelm, Heribert; Nestola, Fabrizio


    Remnants of the fluid phase at ultrahigh pressure (UHP) in subduction environments may be preserved as primary multiphase inclusions in UHP minerals. The mode of crystallization of daughter minerals during precipitation within the inclusion and/or the mechanism of interaction between the fluid at supercritical conditions and the host mineral are still poorly understood from a crystallographic point of view. A case study is represented by garnet-orthopyroxenites from the Maowu Ultramafic Complex (China) deriving from harzburgite precursors metasomatized at ~4 GPa, 750 °C by a silica- and incompatible trace element-rich fluid phase. This metasomatism produced poikilitic orthopyroxene and inclusion-rich garnet porphyroblasts. Solid multiphase primary inclusions in garnet display a size within a few tens of micrometres and negative crystal shapes. Infilling minerals (spinel: 10-20 vol%; amphibole, chlorite, talc, mica: 80-90 vol%) occur with constant volume proportions and derive from trapped solute-rich aqueous fluids. To constrain the possible mode of precipitation of daughter minerals, we performed for the first time a single-crystal X-ray diffraction experiment by synchrotron radiation at Diamond Light Source. In combination with electron probe microanalyses, this measurement allowed the unique identification of each mineral phase and reciprocal orientations. We demonstrated the epitaxial relationship between spinel and garnet and between some hydrous minerals. Such information is discussed in relation to the physico-chemical aspects of nucleation and growth, shedding light on the mode of mineral crystallization from a fluid phase trapped at supercritical conditions.

  13. Critical Regimes of Two-Phase Flows with a Polydisperse Solid Phase

    CERN Document Server

    Barsky, Eugene


    This book brings to light peculiarities of the formation of critical regimes of two-phase flows with a polydisperse solid phase. A definition of entropy is formulated on the basis of statistical analysis of these peculiarities. The physical meaning of entropy and its correlation with other parameters determining two-phase flows are clearly defined. The interrelations and main differences between this entropy and the thermodynamic one are revealed. The main regularities of two-phase flows both in critical and in other regimes are established using the notion of entropy. This parameter serves as a basis for a deeper insight into the physics of the process and for the development of exhaustive techniques of mass exchange estimation in such flows. The book is intended for graduate and postgraduate students of engineering studying two-phase flows, and to scientists and engineers engaged in specific problems of such fields as chemical technology, mineral dressing, modern ceramics, microelectronics, pharmacology, po...

  14. Solid state phase change materials for thermal energy storage in passive solar heated buildings (United States)

    Benson, D. K.; Christensen, C.


    A set of solid state phase change materials was evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol, pentaglycerine and neopentyl glycol. Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature within the range from less than 25 deg to 188 deg. Thermophysical properties such as thermal conductivity, density and volumetric expansion were measured. Computer simulations were used to predict the performance of various Trombe wall designs incorporating solid state phase change materials. Optimum performance was found to be sensitive to the choice of phase change temperatures and to the thermal conductivity of the phase change material. A molecular mechanism of the solid state phase transition is proposed and supported by infrared spectroscopic evidence.

  15. Visualising crystal packing interactions in solid-state NMR: Concepts and applications (United States)

    Zilka, Miri; Sturniolo, Simone; Brown, Steven P.; Yates, Jonathan R.


    In this article, we introduce and apply a methodology, based on density functional theory and the gauge-including projector augmented wave approach, to explore the effects of packing interactions on solid-state nuclear magnetic resonance (NMR) parameters. A visual map derived from a so-termed "magnetic shielding contribution field" can be made of the contributions to the magnetic shielding of a specific site—partitioning the chemical shift to specific interactions. The relation to the established approaches of examining the molecule to crystal change in the chemical shift and the nuclear independent chemical shift is established. The results are applied to a large sample of 71 molecular crystals and three further specific examples from supermolecular chemistry and pharmaceuticals. This approach extends the NMR crystallography toolkit and provides insight into the development of both cluster based approaches to the predictions of chemical shifts and for empirical predictions of chemical shifts in solids.

  16. Phase relations study on the melting and crystallization regions of the Bi-2223 high temperature superconductor

    Directory of Open Access Journals (Sweden)

    Polasek Alexander


    Full Text Available The melting and solidification behavior of Bi2Sr2Ca2Cu3 O10 (Bi-2223 precursors has been studied. Nominal compositions corresponding to excess of liquid, Ca2CuO3 and CuO have been investigated. Each sample was made by packing a precursor powder into a silver crucible, in order to approximately simulate the situation found in 2223 silver-sheathed tapes. The samples were partially melted and then slow-cooled, being quenched from different temperatures and analyzed through X-ray diffraction (XRD and scanning electron microscopy (SEM/EDS. The precursors decomposed peritectically during melting, forming liquid and solid phases. Very long plates with compositions falling in the vicinity of the 2223 primary phase field formed upon slow-cooling. The 2223 phase may have been formed and the results suggest that long grains of this phase might be obtained by melting and crystallization if the exact peritectic region and the optimum processing conditions are found.

  17. [Research on single phase high solid anaerobic digestion of organic fraction of municipal solid wastes]. (United States)

    Jiang, Jian-guo; Wu, Shi-yao; Sui, Ji-chao; Wang, Yan


    Under mesophilic condition (35 degrees C), a bench-scale experiment based on high solid anaerobic digestion process was conducted in a fed-batch single phase reactor to treat the OFMSW. The experiment has lasted for more than half a year and significant results were obtained. At the start-up stage, acidification occurred and showed large inhibition to gas production and the gas production rate once dropped to 0. After pH conditioning, the system has recovered and began to stably running. In this period, gas production rate reached 746.33 L/kg volatile solids (VS) [3.69 L/(L x d)] when the total solids (TS) content of the feeding waste was 24.79% and the VS content was 23.06%. The organic loading rate and hydraulic retention time(HRT) was 4.94 kg/(m3 x d) and 47 d respectively. However, with time went by, accumulated ammonia exceeded its limited value, which is deduced as 2000 mg/L, and the gas production rate dropped below half of the maximum value. By adding chemicals to diminish the amount of ammonia and adjusting the C/N of the feeding, inhibition was relaxed and gas production rate increased gradually.

  18. Description of hard-sphere crystals and crystal-fluid interfaces: a comparison between density functional approaches and a phase-field crystal model. (United States)

    Oettel, M; Dorosz, S; Berghoff, M; Nestler, B; Schilling, T


    In materials science the phase-field crystal approach has become popular to model crystallization processes. Phase-field crystal models are in essence Landau-Ginzburg-type models, which should be derivable from the underlying microscopic description of the system in question. We present a study on classical density functional theory in three stages of approximation leading to a specific phase-field crystal model, and we discuss the limits of applicability of the models that result from these approximations. As a test system we have chosen the three-dimensional suspension of monodisperse hard spheres. The levels of density functional theory that we discuss are fundamental measure theory, a second-order Taylor expansion thereof, and a minimal phase-field crystal model. We have computed coexistence densities, vacancy concentrations in the crystalline phase, interfacial tensions, and interfacial order parameter profiles, and we compare these quantities to simulation results. We also suggest a procedure to fit the free parameters of the phase-field crystal model. Thereby it turns out that the order parameter of the phase-field crystal model is more consistent with a smeared density field (shifted and rescaled) than with the shifted and rescaled density itself. In brief, we conclude that fundamental measure theory is very accurate and can serve as a benchmark for the other theories. Taylor expansion strongly affects free energies, surface tensions, and vacancy concentrations. Furthermore it is phenomenologically misleading to interpret the phase-field crystal model as stemming directly from Taylor-expanded density functional theory.

  19. Controlled In Meso Phase Crystallization – A Method for the Structural Investigation of Membrane Proteins (United States)

    Kubicek, Jan; Schlesinger, Ramona; Baeken, Christian; Büldt, Georg; Schäfer, Frank; Labahn, Jörg


    We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i) the stabilization of membrane proteins in the meso phase, (ii) the control of hydration level and additive concentration by vapor diffusion. The new technology (iii) significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv) direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR) crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII) from Halobacterium salinarum for the first time. PMID:22536388

  20. Controlled in meso phase crystallization--a method for the structural investigation of membrane proteins.

    Directory of Open Access Journals (Sweden)

    Jan Kubicek

    Full Text Available We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i the stabilization of membrane proteins in the meso phase, (ii the control of hydration level and additive concentration by vapor diffusion. The new technology (iii significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII from Halobacterium salinarum for the first time.

  1. Solid sampling determination of magnesium in lithium niobate crystals by graphite furnace atomic absorption spectrometry (United States)

    Dravecz, Gabriella; Laczai, Nikoletta; Hajdara, Ivett; Bencs, László


    The vaporization/atomization processes of Mg in high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS) were investigated by evaporating solid (powder) samples of lithium niobate (LiNbO3) optical single crystals doped with various amounts of Mg in a transversally heated graphite atomizer (THGA). Optimal analytical conditions were attained by using the Mg I 215.4353 nm secondary spectral line. An optimal pyrolysis temperature of 1500 °C was found for Mg, while the compromise atomization temperature in THGAs (2400 °C) was applied for analyte vaporization. The calibration was performed against solid (powered) lithium niobate crystal standards. The standards were prepared with exactly known Mg content via solid state fusion of the oxide components of the matrix and analyte. The correlation coefficient (R value) of the linear calibration was not worse than 0.9992. The calibration curves were linear in the dopant concentration range of interest (0.74-7.25 mg/g Mg), when dosing 3-10 mg of the powder samples into the graphite sample insertion boats. The Mg content of the studied 19 samples was in the range of 1.69-4.13 mg/g. The precision of the method was better than 6.3%. The accuracy of the results was verified by means of flame atomic absorption spectrometry with solution sample introduction after digestion of several crystal samples.

  2. Solid-phase epitaxial film growth and optical properties of a ferroelectric oxide, Sr2Nb2O7 (United States)

    Nezu, Yukio; Zhang, Yu-Qiao; Chen, Chunlin; Ikuhara, Yuichi; Ohta, Hiromichi


    High-quality epitaxial films of a ferroelectric oxide Sr2Nb2O7 were successfully fabricated by solid phase epitaxy (SPE) on (110) LaAlO3 single crystal substrates. In the SPE method, amorphous Sr-Nb-O films are first deposited by pulsed laser deposition at room temperature and then annealed in vacuum at elevated temperatures, resulting in the crystallization of Sr2Nb2O7 with highly ordered atomic arrangement and an atomically flat surface. The refractive index of the resultant film was 2.1, indicating that the dielectric permittivity of the film was in between 20 and 80, which corresponds well with that of single crystal Sr2Nb2O7, demonstrating the effectiveness of the SPE method for the fabrication of high-quality epitaxial films of Sr2Nb2O7.

  3. Improved detection limits for phthalates by selective solid-phase micro-extraction

    KAUST Repository

    Zia, Asif I.


    Presented research reports on an improved method and enhanced limits of detection for phthalates; a hazardous additive used in the production of plastics by solid-phase micro-extraction (SPME) polymer in comparison to molecularly imprinted solid-phase extraction (MISPE) polymer. The polymers were functionalized on an interdigital capacitive sensor for selective binding of phthalate molecules from a complex mixture of chemicals. Both polymers owned predetermined selectivity by formation of valuable molecular recognition sites for Bis (2-ethylhexyl) phthalate (DEHP). Polymers were immobilized on planar electrochemical sensor fabricated on a single crystal silicon substrate with 500 nm sputtered gold electrodes fabricated using MEMS fabrication techniques. Impedance spectra were obtained using electrochemical impedance spectroscopy (EIS) to determine sample conductance for evaluation of phthalate concentration in the spiked sample solutions with various phthalate concentrations. Experimental results revealed that the ability of SPME polymer to adsorb target molecules on the sensing surface is better than that of MISPE polymer for phthalates in the sensing system. Testing the extracted samples using high performance liquid chromatography with photodiode array detectors validated the results.

  4. Electromagnetic properties of high-carbon ferrochrome powders decarburized in solid phase by microwave heating

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wei [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Chen, Jin, E-mail: [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Guo, Lina; Hao, Jiujiu; Han, Peide [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Liu, Jinying [The 12th Institute of China Electronics Technology Group Corporation, Beijing 100016 (China)


    Highlights: • High-carbon ferrochrome powders present diamagnetism. • We study the effect of temperature and time on electromagnetic properties. • The relative permittivity and permeability exhibit an opposite change trend. • The absorption peak shifts to lower frequency with the increasing temperature. - Abstract: During solid-phase decarburization, the changes of the electromagnetic properties can reflect the variation degree of material components. High-carbon ferrochrome powders (HCFCP) with addition of CaCO{sub 3} were decarburized in solid phase by microwave heating and the electromagnetic properties of the decarburized materials were investigated. With increasing in heating temperature from 1173 to 1473 K, the relative permittivity of the decarburized materials increases initially and then decreases, whereas the relative permeability exhibits an opposite change trend. As holding time ranges from 40 to 60 min at 1273 K, the relative permittivity and dielectric loss factor tend to decrease while the relative permeability and magnetic loss factor tend to increase, corresponding to the maximum mean velocity of decarburization. In microwave fields, electromagnetic properties of the decarburized materials principally vary with carbon content, C-vacancies and crystal structure, and their changes in turn affect the interaction of microwaves with the decarburized materials.

  5. Nucleation of ordered solid phases of proteins via a disordered high-density state: Phenomenological approach (United States)

    Pan, Weichun; Kolomeisky, Anatoly B.; Vekilov, Peter G.


    Nucleation of ordered solid phases of proteins triggers numerous phenomena in laboratory, industry, and in healthy and sick organisms. Recent simulations and experiments with protein crystals suggest that the formation of an ordered crystalline nucleus is preceded by a disordered high-density cluster, akin to a droplet of high-density liquid that has been observed with some proteins; this mechanism allowed a qualitative explanation of recorded complex nucleation kinetics curves. Here, we present a simple phenomenological theory that takes into account intermediate high-density metastable states in the nucleation process. Nucleation rate data at varying temperature and protein concentration are reproduced with high fidelity using literature values of the thermodynamic and kinetic parameters of the system. Our calculations show that the growth rate of the near-critical and supercritical ordered clusters within the dense intermediate is a major factor for the overall nucleation rate. This highlights the role of viscosity within the dense intermediate for the formation of the ordered nucleus. The model provides an understanding of the action of additives that delay or accelerate nucleation and presents a framework within which the nucleation of other ordered protein solid phases, e.g., the sickle cell hemoglobin polymers, can be analyzed.

  6. Volume phase holographic gratings for astronomy based on solid photopolymers (United States)

    Zanutta, Alessio; Bianco, Andrea; Insausti, Maider; Garzón, Francisco


    Volume Phase Holographic Gratings (VPHG) are gaining more and more interest as optical dispersing elements in new astronomical spectrographs at low and medium resolution. A key point is the development of new photosensitive materials suitable to produce VPHGs that match the stringent requirements of the astronomical environment. Here we report on the performances of VPHG based on Bayfol®HX solid photopolymer films developed by Bayer MaterialScience AG. Parameters affecting the grating efficiency (e. g. photopolymer film thickness and refractive index modulation) are measured and linked to the performances of VPHG working in the VIS-NIR region. Moreover, the behavior at low temperature and the aging properties of such materials/gratings are reported. Substantial efficiency gains on a new VPHG installed at the Asiago's spectrograph are shown and proven on the observation of a standard star (hr5501).


    Directory of Open Access Journals (Sweden)



    Full Text Available The industrial production of metals and metalloids had known a huge development in the last decades. Under the augmentation of world demand on refined products of consumption, things that has been traduced by some sub products, spatially refined iron in high furnaces. The byproducts named scoria, its source is El Hadjar plant, which constitutes an environmental and ecological problem. The work presented is a part of a huge project witch concerns the valorization of natural and artificial sub products, the agro-alimental, local herbs, for medical and cosmeticology uses. The research axe, specialized in preparing adsorbent solid phases is situated in our global project of research in which we are aiming to find a better use for the sub product of the High Furnace, (H.F   in order to giveitother values. The memory of this publication spreads on a bibliographic study; followed by experimental works from witch we obtained good results.

  8. Handles for Fmoc solid-phase synthesis of protected peptides. (United States)

    Góngora-Benítez, Miriam; Tulla-Puche, Judit; Albericio, Fernando


    Protected peptide fragments are valuable building blocks for the assembly of large peptide sequences through fragment condensation approaches, whereas protected peptides are typically synthesized for the preparation of amide-bridge cyclic peptides in solution. Efficient synthesis of both protected peptides and protected peptide fragments by solid-phase peptide synthesis methodology requires handles that attach the growing peptides to the polymeric support and can be cleaved under appropriate conditions, while maintaining intact the side-chain protecting groups. Here, we provide an overview of attachment methods described in the literature for the preparation of protected peptides using Fmoc/tBu chemistry, including the most commonly used acid-labile linkers along with the most recent and sophisticated.

  9. Microwave heating in solid-phase peptide synthesis

    DEFF Research Database (Denmark)

    Pedersen, Søren Ljungberg; Shelton, Anne Pernille Tofteng; Malik, Leila


    The highly refined organic chemistry in solid-phase synthesis has made it the method of choice not only to assemble peptides but also small proteins - mainly on a laboratory scale but increasingly also on an industrial scale. While conductive heating occasionally has been applied to peptide...... synthesis, precise microwave irradiation to heat the reaction mixture during coupling and N(a)-deprotection has become increasingly popular. It has often provided dramatic reductions in synthesis times, accompanied by an increase in the crude peptide purity. Microwave heating has been proven especially...... relevant for sequences which might form ß-sheet type structures and for sterically difficult couplings. The beneficial effect of microwave heating appears so far to be due to the precise nature of this type of heating, rather than a peptide-specific microwave effect. However, microwave heating...

  10. A Neutron Scattering Kernel of Solid Methane in phase II (United States)

    Shin, Yunchang; Snow, William Michael; Liu, Cnen-Yu; Lavelle, Christopher M.; Baxter, David V.


    A neutron scattering cross section model of solid methane was studied for the cold neutron moderator of Low Energy Neutron Source (LENS) at IUCF/Indiana University especially in temperature range of 20.4 4K. The analytical scattering kernel was adapted from al .[1][2] to describe molecular rotation in this temperature range. This model includes a molecular translation and intra-molecular vibration as well as the rotational degree of freedom in effective ways. For more broad applications into monte carlo simulations, neutron scattering libraries for MCNP were produced from the frequency spectrums using NJOY code. We have tested this newly- developed scattering kernels for phase II solid methane by calculating the neutron spectral intensity expected from the methane moderator at the LENS neutron source using MCNP. The predictions are compared to the measured energy spectra. The simulations agree with the measurement data at both temperatures. The simulation results show good agreement with measurement data in different temperatures. [1] Y. Ozaki, Y. Kataoka, and T. Yamamoto, The Journal of Chemical Physics 73, 3442 (1980). [2] Y. Ozaki, Y. Kataoka, K. Otaka, and T. Yamamoto, Can. J. Physics. 59, 275 (1981).

  11. Solid phase fermentation of leaf biomass to biogas

    Energy Technology Data Exchange (ETDEWEB)

    Anand, V.; Chanakya, H.N.; Rajan, M.G.C. (ASTRA, Indian Institute of Science, Bangalore (India))


    This paper describes a simple technique for the fermentation of untreated or partly-treated leafy biomass in a digester of novel design without incurring the normal problems of feeding, floating and scum formation of feed, etc. The solid phase fermentation studied consists of a bed of biomass frequently sprinkled with an aqueous bacterial inoculum and recycling the leachate to conserve moisture and improve the bacterial dispersion in the bed. The decomposition of the leaf biomass and water hyacinth substrates used in this study was rapid, taking 45 and 30 days for the production of 250 and 235l biogas per kg total solids (TS) respectively, for the above mentioned substrates at a daily sprinkled volume of 26 ml cm{sup -2} of bed per day sprinkled at 12 h intervals. Very little volatile fatty acid (VFA) intermediates accumulated in the liquid sprinkled, suggesting acidogenesis to be rate-limiting in this process. From the pattern of VFA and gas produced it is concluded that most of the biogas produced is from the biomass bed, thus making the operation of a separate methanogenic reactor unnecessary. 11 refs., 7 figs., 2 tabs.

  12. Optically induced structural phase transitions in ion Coulomb crystals

    DEFF Research Database (Denmark)

    Horak, Peter; Dantan, Aurelien Romain; Drewsen, Michael


    We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures, such as b......We investigate numerically the structural dynamics of ion Coulomb crystals confined in a three-dimensional harmonic trap when influenced by an additional one-dimensional optically induced periodical potential. We demonstrate that transitions between thermally excited crystal structures...

  13. Municipal solid waste development phases: Evidence from EU27. (United States)

    Vujić, Goran; Gonzalez-Roof, Alvaro; Stanisavljević, Nemanja; Ragossnig, Arne M


    Many countries in the European Union (EU) have very developed waste management systems. Some of its members have managed to reduce their landfilled waste to values close to zero during the last decade. Thus, European Union legislation is very stringent regarding waste management for their members and candidate countries, too. This raises the following questions: Is it possible for developing and developed countries to comply with the European Union waste legislation, and under what conditions? How did waste management develop in relation to the economic development in the countries of the European Union? The correlation between waste management practices and economic development was analysed for 27 of the European Union Member States for the time period between 1995 and 2007. In addition, a regression analysis was performed to estimate landfilling of waste in relation to gross domestic product for every country. The results showed a strong correlation between the waste management variables and the gross domestic product of the EU27 members. The definition of the municipal solid waste management development phases followed a closer analysis of the relation between gross domestic product and landfilled waste. The municipal solid waste management phases are characterised by high landfilling rates at low gross domestic product levels, and landfilling rates near zero at high gross domestic product levels. Hence the results emphasize the importance of wider understanding of what is required for developing countries to comply with the European Union initiatives, and highlight the importance of allowing developing countries to make their own paths of waste management development. © The Author(s) 2015.

  14. Phase transitions in A 4 Li (HSO 4) 3 (SO 4); A= Rb, K: Single crystal ...

    Indian Academy of Sciences (India)

    Keywords. Phase transition; ferroelastic; cryo-crystallography; crystal structure. Abstract. The crystal structure of ferroelastic Rb4Li(HSO4)3(SO4) has been determined at two temperatures, which indicates a structural phase transition, tetragonal 43 with = 7.629(1) Å, = 29.497(2) Å at 293 K and monoclinic 21 with  ...

  15. Liquid Crystal Phases of Colloidal Platelets and their Use as Nanocomposite Templates

    NARCIS (Netherlands)

    Mourad, M.C.D.|info:eu-repo/dai/nl/304837563


    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

  16. A Scanning Hologram Recorded by Phase Conjugate Property of Nonlinear Crystals

    DEFF Research Database (Denmark)

    Zi-Liang, Ping; Dalsgaard, Erik


    A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given.......A methode of recording a scanning hologram with phase conjugate property of nonlinear crystal is provided. The principle of recording, setup and experiments are given....

  17. On the crystal structure of Z-phase Cr(V,Nb)N

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John; Grumsen, Flemming Bjerg


    The Z-phase Cr(YNb)N particles in various 9 to 12 pct Cr creep-resistant steels were investigated with electron diffraction, energy dispersive spectroscopy (EDS), and electron energy loss spectroscopy(EELS). In addition to the well-known tetragonal crystal structure for Z phase, a cubic crystal s...

  18. New methods and materials for solid phase extraction and high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, Philip John [Iowa State Univ., Ames, IA (United States)


    This paper describes methods for solid phase extraction and high performance liquid chromatography (HPLC). The following are described: Effects of Resin Sulfonation on the Retention of Polar Organic Compounds in Solid Phase Extraction; Ion-Chromatographic Separation of Alkali Metals In Non-Aqueous Solvents; Cation-Exchange Chromatography in Non-Aqueous Solvents; and Silicalite As a Stationary Phase For HPLC.

  19. Comparative solution and solid-phase glycosylations toward a disaccharide library

    DEFF Research Database (Denmark)

    Agoston, K.; Kröger, Lars; Agoston, Agnes


    A comparative study on solution-phase and solid-phase oligosaccharide synthesis was performed. A 16-member library containing all regioisomers of Glc-Glc, Glc-Gal, Gal-Glc, and Gal-Gal disaccharides was synthesized both in solution and on solid phase. The various reaction conditions for different...

  20. Solid-Phase Organic Chemistry: Synthesis of 2β-(HeterocyclylthiomethylPenam Derivatives on Solid Support

    Directory of Open Access Journals (Sweden)

    Ernesto G. Mata


    Full Text Available The synthesis of 2β-(heterocyclylthiomethylpenam derivatives on solid support has been developed. Compounds are obtained in good to high yields (based on loading of the original resin. The key step is the solid-phase double rearrangement of the corresponding penicillin sulfoxide.

  1. Effect of temperature on the value of the surface potential and the phase state of 4’-n-octyl-4-p-cyanobiphenyl liquid crystal (United States)

    Chumakov, A. S.; Al-Alwani, Ammar J. K.; Gorbachev, I. A.; Glukhovskoy, E. G.; Usoltseva, N. V.


    Liquid crystals are one of the most interesting materials for various applications. The article considers the influence of temperature to the phase change and the value of surface potential of 4’-n-octyl-4-p-cyanobiphenyl liquid crystal Langmuir monolayers. These parameters have a critical role in process of transfer monolayers to the solid substrate and for further using of them. It is shown that with increasing temperature of subphase leads to the monolayer of liquid crystal becomes isotropic and exhibits a gradual decrease in the surface potential in process of compression.

  2. Development of novel solid-phase protein formulations (United States)

    Montalvo Ortiz, Brenda Liz

    Proteins are the next-generation drugs for the treatment of several diseases. However, the number of protein drugs is still limited due to the physical or chemical instability of proteins during processing, formulation, storage, and delivery. The formulation of proteins at the solid state has advantages over liquid state, such as improved stability during long-term storage and delivery and decreases transportation costs. In this dissertation, we developed new solid-phase protein formulations in which the integrity of the protein was not compromised. The long term goal of this research was to use these protein formulations to improve protein stability in drug delivery devices, such as poly(lactic-co-glycolic) acid (PLGA). The first solid-phase protein formulation developed in this investigation was named "glassification". We proposed glassification as an alternative protein dehydration technique to the common used one, lyophilization, because this last method involves a series of steps which are detrimental to protein structure and stability. The glassification method consisted on protein dehydration by the use of organic solvents. As a result of the glassification process a small (micrometer size range) protein solid bead was obtained. The proteins used to study the glassification process were lysozyme (LYS), alpha-chymotrypsin (CHYMO) and horseradish peroxidase (HRP). These studies revealed that the glassification process itself did not alter protein structure and the activity was preserved. Ethyl acetate was the most effective organic solvent for protein glassification because it led to the highest protein residual activity, no insoluble aggregate formation and is a relatively non-toxic solvent, which allow the incorporation of these protein microparticles in PLGA microspheres. The incorporation of spherical HRP microparticles into PLGA microspheres resulted in superior properties when compared with encapsulated lyophilized HRP powder, such as improved release

  3. Immunochemical cross-reactivity between albumin and solid-phase adsorbed histamine

    DEFF Research Database (Denmark)

    Poulsen, L K; Nolte, H; Søndergaard, I


    For production of an antibody against histamine, this was coupled to human serum albumin (HSA) and used for immunization of rabbits. To test the antiserum, an immunoradiometric assay was developed comprising solid-phase bound histamine, antisera and radiolabelled protein A. Titration and inhibition...... experiments revealed that histamine adsorbed onto a solid-phase could bind the antiserum. However, neither free histamine nor histamine coupled to unrelated carriers could inhibit the binding of antiserum to the solid-phase histamine. Cross-reactivity was demonstrated between HSA and solid-phase bound...

  4. Crystal structure and tautomerism of Pigment Yellow 138 determined by X-ray powder diffraction and solid-state NMR

    DEFF Research Database (Denmark)

    Gumbert, Silke D.; Körbitzer, Meike; Alig, Edith


    The crystal structure of C.I. Pigment Yellow 138 was determined from X-ray powder diffraction data using real-space methods with subsequent Rietveld refinements. The tautomeric state was investigated by solid-state 1D and 2D multinuclear NMR experiments. In the crystals, the compound exhibits...... is not a packing effect, but caused by intramolecular steric hindrance....

  5. Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates. (United States)

    Chadwick, F Mark; McKay, Alasdair I; Martinez-Martinez, Antonio J; Rees, Nicholas H; Krämer, Tobias; Macgregor, Stuart A; Weller, Andrew S


    Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArF4] (NBA = norbornane; ArF = 3,5-(CF3)2C6H3) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy2PCH2CH2PCy2)(alkene) x ][BArF4] are formed. The ethene (x = 2) complex, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BArF4]-Oct, has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy2PCH2CH2PCy2)(ethene)2][BArF4]-Hex, that has a hexagonal microporous structure (P6322). The propene complex (x = 1) [Rh(Cy2PCH2CH2PCy2)(propene)][BArF4] is characterized as having a π-bound alkene with a supporting γ-agostic Rh···H3C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d3-propene, H2C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000

  6. Melting and crystallization of poly(3-hydroxybutyrate: effect of heating/cooling rates on phase transformation

    Directory of Open Access Journals (Sweden)

    Renate Maria Ramos Wellen


    Full Text Available AbstractWe studied the crystallization and melting phenomena of poly (3- hydroxybutyrate (PHB, a biodegradable and biocompatible semi-crystalline thermoplastic, obtained from renewable resources. Its high crystallinity motivated several studies on crystallization and melting behavior, and also on ways to increase the amorphous polymer fraction. The effect of heating and cooling rates on the crystallization and melting of commercial PHB was investigated by differential scanning calorimetry. Several rates, ranging from 2.5 to 20 °C min–1, were used to study the phase changes during heating/cooling/reheating cycles. The results showed that PHB partially crystallizes from the melt during the cooling cycle and partially cold crystallizes on reheating, and that the relative amount of polymer crystallizing in each stage strongly depends on the cooling rate. The melt and cold crystallization temperatures, as well as the rates of phase change, depend strongly on the cooling and heating rates.

  7. Phase-field crystal modeling of equilibrium bcc-liquid interfaces (United States)

    Wu, Kuo-An; Karma, Alain


    We investigate the equilibrium properties of bcc-liquid interfaces modeled with a continuum phase-field crystal (PFC) approach [K. R. Elder and M. Grant, Phys. Rev. E 70, 051605 (2004)]. A multiscale analysis of the PFC model is carried out which exploits the fact that the amplitudes of crystal density waves decay slowly into the liquid in the physically relevant limit where the freezing transition is weakly first order. This analysis yields a set of coupled equations for these amplitudes that is similar to the set of equations derived from Ginzburg-Landau (GL) theory [K.-A. Wu , Phys. Rev. B 73, 094101 (2006)]. The two sets only differ in the details of higher order nonlinear couplings between different density waves, which is determined by the form of the nonlinearity assumed in the PFC model and by the ansatz that all polygons with the same number of sides have equal weight in GL theory. Despite these differences, for parameters (liquid structure factor and solid density wave amplitude) of Fe determined from molecular dynamics (MD) simulations, the PFC and GL amplitude equations yield very similar predictions for the overall magnitude and anisotropy of the interfacial free-energy and density wave profiles. These predictions are compared with MD simulations as well as numerical solutions of the PFC model.

  8. Crystal Field Parameters and Phase Transitions in ErSb

    DEFF Research Database (Denmark)

    Shapiro, S. M.; Bak, P.


    The crystal field levels of the Er ion in a single crystal of ErSb have been measured by inelastic neutron scattering. The crystal field parameters obtained by a least squares fit to the spectra at several temperatures are: B4 = (0·473 ± 0·005) × 10−2°K and B6 = (0·59 ± 0·06) × 10−5°K, which differ...

  9. Shock and Microstructural Characterization of the α-ω Phase Transition in Titanium Crystals (United States)

    Morrow, Benjamin M.; Rigg, Paulo A.; Jones, David R.; Addessio, Francis L.; Trujillo, Carl P.; Saavedra, Ramon A.; Martinez, Daniel T.; Cerreta, Ellen K.


    A multicrystal comprised of a small number of large crystals of high-purity titanium and a [0001] oriented high-purity single crystal titanium sample were shock loaded using gas gun plate impact experiments. Tests were performed at stresses above the α {-}ω phase transition stress (for high-purity polycrystalline specimens) to observe the behavior of oriented crystals under similar conditions. Post-mortem characterization of the shocked microstructure was conducted on the single crystal sample to measure textures, and quantify phases and twinning. The apparent activation of plastic and transformation mechanisms was dependent upon crystal orientation. Specifically, the [0001] crystal showed a higher Hugoniot elastic limit than the [10\\bar{1}0] or [3\\bar{1}\\bar{4}4] orientations. The slope of velocity as a function of time was lower in the [0001] orientation than the other orientations during plastic deformation, indicating sluggish transformation kinetics for the α to ω phase transition for the [0001] oriented crystal. Microtexture measurements of a recovered [0001] oriented single crystal revealed the presence of retained ω phase after unloading, with orientations of the constituent phase fractions indicative of the forward α → ω transition, rather than the reverse ω → α transition, suggesting that the material never achieved a state of 100% ω phase.

  10. Effect of gamma-irradiation defects on ferroelectric phase transitions of TGSe and DTGSs crystals

    CERN Document Server

    Song, Y W


    The influence of gamma-irradiation defects upon the second-order phase transition in TGSe and the first-order phase transition in DTGSe crystals was studied by means of specific-heat measurements. gamma-irradiation defects changed the behavior of the thermodynamic properties, and the order of the phase transition was changed from the first to the second in the DTGSe crystal. The kinetics of gamma-irradiation defects was studied.

  11. Polymerizable Ionic Liquid Crystals Comprising Polyoxometalate Clusters toward Inorganic-Organic Hybrid Solid Electrolytes

    Directory of Open Access Journals (Sweden)

    Takeru Ito


    Full Text Available Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is employing a thermally-stable inorganic component and a structurally-flexible organic moiety to construct inorganic-organic hybrid materials. Ionic liquids as the organic component will be advantageous for the emergence of high conductivity, and polyoxometalate, such as heteropolyacids, are well-known as inorganic proton conductors. Here, newly-designed ionic liquid imidazolium cations, having a polymerizable methacryl group (denoted as MAImC1, were successfully hybridized with heteropolyanions of [PW12O40]3− (PW12 to form inorganic-organic hybrid monomers of MAImC1-PW12. The synthetic procedure of MAImC1-PW12 was a simple ion-exchange reaction, being generally applicable to several polyoxometalates, in principle. MAImC1-PW12 was obtained as single crystals, and its molecular and crystal structures were clearly revealed. Additionally, the hybrid monomer of MAImC1-PW12 was polymerized by a radical polymerization using AIBN as an initiator. Some of the resulting inorganic-organic hybrid polymers exhibited conductivity of 10−4 S·cm−1 order under humidified conditions at 313 K.

  12. The non-equilibrium phase diagrams of flow-induced crystallization and melting of polyethylene. (United States)

    Wang, Zhen; Ju, Jianzhu; Yang, Junsheng; Ma, Zhe; Liu, Dong; Cui, Kunpeng; Yang, Haoran; Chang, Jiarui; Huang, Ningdong; Li, Liangbin


    Combining extensional rheology with in-situ synchrotron ultrafast x-ray scattering, we studied flow-induced phase behaviors of polyethylene (PE) in a wide temperature range up to 240 °C. Non-equilibrium phase diagrams of crystallization and melting under flow conditions are constructed in stress-temperature space, composing of melt, non-crystalline δ, hexagonal and orthorhombic phases. The non-crystalline δ phase is demonstrated to be either a metastable transient pre-order for crystallization or a thermodynamically stable phase. Based on the non-equilibrium phase diagrams, nearly all observations in flow-induced crystallization (FIC) of PE can be well understood. The interplay of thermodynamic stabilities and kinetic competitions of the four phases creates rich kinetic pathways for FIC and diverse final structures. The non-equilibrium flow phase diagrams provide a detailed roadmap for precisely processing of PE with designed structures and properties.

  13. Solid-phase microextraction for bioconcentration studies according to OECD TG 305

    National Research Council Canada - National Science Library

    Düring, Rolf-Alexander; Böhm, Leonard; Schlechtriem, Christian


    .... Solid-phase microextraction is especially capable of extracting total water concentrations as well as the freely dissolved fraction of analytes in the water phase, which is available for bioconcentration in fish...

  14. Impact of surfactants on the crystallization of aqueous suspensions of celecoxib amorphous solid dispersion spray dried particles. (United States)

    Chen, Jie; Ormes, James D; Higgins, John D; Taylor, Lynne S


    Amorphous solid dispersions are frequently prepared by spray drying. It is important that the resultant spray dried particles do not crystallize during formulation, storage, and upon administration. The goal of the current study was to evaluate the impact of surfactants on the crystallization of celecoxib amorphous solid dispersions (ASD), suspended in aqueous media. Solid dispersions of celecoxib with hydroxypropylmethylcellulose acetate succinate were manufactured by spray drying, and aqueous suspensions were prepared by adding the particles to acidified media containing various surfactants. Nucleation induction times were evaluated for celecoxib in the presence and absence of surfactants. The impact of the surfactants on drug and polymer leaching from the solid dispersion particles was also evaluated. Sodium dodecyl sulfate and Polysorbate 80 were found to promote crystallization from the ASD suspensions, while other surfactants including sodium taurocholate and Triton X100 were found to inhibit crystallization. The promotion or inhibition of crystallization was found to be related to the impact of the surfactant on the nucleation behavior of celecoxib, as well as the tendency to promote leaching of the drug from the ASD particle into the suspending medium. It was concluded that surfactant choice is critical to avoid failure of amorphous solid dispersions through crystallization of the drug.

  15. Effect of Blumea balsamifera extract on the phase and morphology of calcium oxalate crystals. (United States)

    Montealegre, Charlimagne M; De Leon, Rizalinda L


    Calcium oxalate crystals are found in majority of kidney stones with calcium oxalate monohydrate (COM) as one of the primary types of kidney stones. Various methods of treatment exist, including herbal treatment in the Philippines that uses the medicinal herb Blumea balsamifera (B. balsamifera). The effect of B. balsamifera extract on the morphology of calcium oxalate crystals was studied by light microscopy, image analysis, powder X-ray diffraction and scanning electron microscopy. The extract decreased the crystal size by 5.22%-82.62% depending on the degree of supersaturation. Through analysis of the projected area of the crystals, the extract was found to shift the phase of the crystals from COM to calcium oxalate dihydrate (COD). This shift in phase is significant with a COM to COD shift of 88.26% at 0.5 mg/mL of extract and 91.53% at 1.0 mg/mL of extract. Scanning election microscopic (SEM) images revealed aggregation of crystals at 0 mg/mL of extract. At 1.0 mg/mL of extract, the scanning electron micrographs showed discernible crystal unit boundaries. B. balsamifera extract was observed to have decreased crystal size, shifted crystal phase from COM to COD and prevented the aggregation of calcium oxalate crystals.

  16. Microwave Crystallization of Lithium Aluminum Germanium Phosphate Solid-State Electrolyte

    Directory of Open Access Journals (Sweden)

    Morsi M. Mahmoud


    Full Text Available Lithium aluminum germanium phosphate (LAGP glass-ceramics are considered as promising solid-state electrolytes for Li-ion batteries. LAGP glass was prepared via the regular conventional melt-quenching method. Thermal, chemical analyses and X-ray diffraction (XRD were performed to characterize the prepared glass. The crystallization of the prepared LAGP glass was done using conventional heating and high frequency microwave (MW processing. Thirty GHz microwave (MW processing setup were used to convert the prepared LAGP glass into glass-ceramics and compared with the conventionally crystallized LAGP glass-ceramics that were heat-treated in an electric conventional furnace. The ionic conductivities of the LAGP samples obtained from the two different routes were measured using impedance spectroscopy. These samples were also characterized using XRD and scanning electron microscopy (SEM. Microwave processing was successfully used to crystallize LAGP glass into glass-ceramic without the aid of susceptors. The MW treated sample showed higher total, grains and grain boundary ionic conductivities values, lower activation energy and relatively larger-grained microstructure with less porosity compared to the corresponding conventionally treated sample at the same optimized heat-treatment conditions. The enhanced total, grains and grain boundary ionic conductivities values along with the reduced activation energy that were observed in the MW treated sample was considered as an experimental evidence for the existence of the microwave effect in LAGP crystallization process. MW processing is a promising candidate technology for the production of solid-state electrolytes for Li-ion battery.

  17. Solid-Phase Microextraction and the Human Fecal VOC Metabolome (United States)

    Dixon, Emma; Clubb, Cynthia; Pittman, Sara; Ammann, Larry; Rasheed, Zeehasham; Kazmi, Nazia; Keshavarzian, Ali; Gillevet, Pat; Rangwala, Huzefa; Couch, Robin D.


    The diagnostic potential and health implications of volatile organic compounds (VOCs) present in human feces has begun to receive considerable attention. Headspace solid-phase microextraction (SPME) has greatly facilitated the isolation and analysis of VOCs from human feces. Pioneering human fecal VOC metabolomic investigations have utilized a single SPME fiber type for analyte extraction and analysis. However, we hypothesized that the multifarious nature of metabolites present in human feces dictates the use of several diverse SPME fiber coatings for more comprehensive metabolomic coverage. We report here an evaluation of eight different commercially available SPME fibers, in combination with both GC-MS and GC-FID, and identify the 50/30 µm CAR-DVB-PDMS, 85 µm CAR-PDMS, 65 µm DVB-PDMS, 7 µm PDMS, and 60 µm PEG SPME fibers as a minimal set of fibers appropriate for human fecal VOC metabolomics, collectively isolating approximately 90% of the total metabolites obtained when using all eight fibers. We also evaluate the effect of extraction duration on metabolite isolation and illustrate that ex vivo enteric microbial fermentation has no effect on metabolite composition during prolonged extractions if the SPME is performed as described herein. PMID:21494609

  18. Binding of properdin to solid-phase immune complexes

    DEFF Research Database (Denmark)

    Junker, A; Baatrup, G; Svehag, S E


    The capacity of serum to support deposition of C3, properdin and factor B was studied by enzyme-linked immunosorbent assay using solid-phase immune complexes (IC) for activation of complement. Deposition of C3 and properdin occurred in fairly dilute normal human serum (NHS), but factor B uptake...... was hardly detectable. Alternative pathway-mediated deposition of C3 with slow kinetics was demonstrated in C2-deficient serum and in NHS depleted of C1q, factor D and properdin (C1qDP-depleted serum) after reconstitution with factor D and properdin. Efficient uptake of properdin required a functional...... classical pathway, in the presence of which C3 and properdin were rapidly deposited onto the IC. Judging from findings in C3-deficient serum, factor I-deficient serum, and C1qDPB-depleted serum, the uptake of properdin was strictly C3-dependent, and did not require the presence of factors B and D. Thus, C3b...

  19. Solid-phase microextraction and the human fecal VOC metabolome.

    Directory of Open Access Journals (Sweden)

    Emma Dixon

    Full Text Available The diagnostic potential and health implications of volatile organic compounds (VOCs present in human feces has begun to receive considerable attention. Headspace solid-phase microextraction (SPME has greatly facilitated the isolation and analysis of VOCs from human feces. Pioneering human fecal VOC metabolomic investigations have utilized a single SPME fiber type for analyte extraction and analysis. However, we hypothesized that the multifarious nature of metabolites present in human feces dictates the use of several diverse SPME fiber coatings for more comprehensive metabolomic coverage. We report here an evaluation of eight different commercially available SPME fibers, in combination with both GC-MS and GC-FID, and identify the 50/30 µm CAR-DVB-PDMS, 85 µm CAR-PDMS, 65 µm DVB-PDMS, 7 µm PDMS, and 60 µm PEG SPME fibers as a minimal set of fibers appropriate for human fecal VOC metabolomics, collectively isolating approximately 90% of the total metabolites obtained when using all eight fibers. We also evaluate the effect of extraction duration on metabolite isolation and illustrate that ex vivo enteric microbial fermentation has no effect on metabolite composition during prolonged extractions if the SPME is performed as described herein.

  20. Molecularly imprinted solid phase extraction of fluconazole from pharmaceutical formulations. (United States)

    Manzoor, S; Buffon, R; Rossi, A V


    This work encompasses a direct and coherent strategy to synthesise a molecularly imprinted polymer (MIP) capable of extracting fluconazole from its sample. The MIP was successfully prepared from methacrylic acid (functional monomer), ethyleneglycoldimethacrylate (crosslinker) and acetonitrile (porogenic solvent) in the presence of fluconazole as the template molecule through a non-covalent approach. The non-imprinted polymer (NIP) was prepared following the same synthetic scheme, but in the absence of the template. The data obtained from scanning electronic microscopy, infrared spectroscopy, thermogravimetric and nitrogen Brunauer-Emmett-Teller plot helped to elucidate the structural as well as the morphological characteristics of the MIP and NIP. The application of MIP as a sorbent was demonstrated by packing it in solid phase extraction cartridges to extract fluconazole from commercial capsule samples through an offline analytical procedure. The quantification of fluconazole was accomplished through UPLC-MS, which resulted in LOD≤1.63×10(-10) mM. Furthermore, a high percentage recovery of 91±10% (n=9) was obtained. The ability of the MIP for selective recognition of fluconazole was evaluated by comparison with the structural analogues, miconazole, tioconazole and secnidazole, resulting in percentage recoveries of 51, 35 and 32%, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Automated solid-phase peptide synthesis to obtain therapeutic peptides

    Directory of Open Access Journals (Sweden)

    Veronika Mäde


    Full Text Available The great versatility and the inherent high affinities of peptides for their respective targets have led to tremendous progress for therapeutic applications in the last years. In order to increase the drugability of these frequently unstable and rapidly cleared molecules, chemical modifications are of great interest. Automated solid-phase peptide synthesis (SPPS offers a suitable technology to produce chemically engineered peptides. This review concentrates on the application of SPPS by Fmoc/t-Bu protecting-group strategy, which is most commonly used. Critical issues and suggestions for the synthesis are covered. The development of automated methods from conventional to essentially improved microwave-assisted instruments is discussed. In order to improve pharmacokinetic properties of peptides, lipidation and PEGylation are described as covalent conjugation methods, which can be applied by a combination of automated and manual synthesis approaches. The synthesis and application of SPPS is described for neuropeptide Y receptor analogs as an example for bioactive hormones. The applied strategies represent innovative and potent methods for the development of novel peptide drug candidates that can be manufactured with optimized automated synthesis technologies.

  2. Electroenhanced solid-phase microextraction of methamphetamine with commercial fibers. (United States)

    Tan, Tsze Yin; Basheer, Chanbasha; Yan Ang, Melgious Jin; Lee, Hian Kee


    Electroenhanced solid-phase microextraction (EE-SPME) method with gas chromatographic mass spectrometric analysis was investigated for the determination of methamphetamine in urine sample with commercial fibers. In this approach, commercial SPME fibers were used in direct immersion mode with an applied potential to extract methamphetamine. EE-SPME was more effective in the extraction compared to conventional SPME (i.e. application of potential). The method was simple to use, and avoided the need for alkalization and derivatization of methamphetamine. Experimental conditions were optimized to achieve better extraction performance. Various conditions including applied potential, sample pH, extraction and desorption time were investigated. Based on the optimized conditions, EE-SPME achieved a higher enrichment factor of 159-fold than conventional SPME. The calibration plot under the best selected parameters was linear in the range of 0.5-15ng/mL (r=0.9948). The feasibility of EE-SPME was demonstrated by applying it to the analysis of human urine samples. The limit of detection of methamphetamine was 0.25ng/mL with a satisfactory relative standard deviation of 6.12% (n=3) in human urine. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. NMR studies of a D/sub 2/ single crystal in the ordered phase

    Energy Technology Data Exchange (ETDEWEB)

    Banke, R.; Li, X.; Clarkson, D.; Meyer, H.


    The authors report the first experimental study of the NMR lineshape anisotropy in the orientationally ordered cubic phase of a D/sub 2/ single crystal. The para-D/sub 2/ concentration covered the range 0.72 < X < 0.82. The observed line shapes were obtained by means of Fourier transform techniques from the solid echoes recorded with a pulsed NMR spectrometer operating at 5.9 MHz. Theoretical line shapes and their second moments for p-D/sub 2/ (with angular momentum J = 1 and spin I = 1) and for o-D/sub 2/ (with J = 0, I = 2) were calculated as a function of the applied field direction from the theory by A.B. Harris. Good agreement was obtained for all directions, provided that, just as for solid H/sub 2/ a Gaussian function for the distribution of molecular axial alignment was assumed with an rms spreading angle of approx. 6 deg for X = 0.77. No change in the anisotropy of the second moment in the disordered phase was detected between the initial (hcp) crystal and after repeated thermal cyclings through the martensitic transition. This result implies no change in the orientation of the plane for the sliding nets during repeated passages through the transition. Furthermore, they report measurements of the longitudinal relaxation time for both p-D/sub 2/ and o-H/sub 2/ versus T over the temperature range 0.5 < T < 3.5 K. The complex behavior reported previously for both H/sub 2/ and D/sub 2/ was confirmed. Measurements of the relaxation times as a function of the applied field direction in the ordered phase at 1.2 K showed no anisotropy within experimental error, and this result is discussed in the light of predictions by Hardy and Berlinsky. Finally, the polarization of the J = 0 molecules is studied as a function of the concentration X of the J = 1 molecules and their state of orientational order over a wide range of X and T in the ordered and disordered states.

  4. Powder crystallography of pharmaceutical materials by combined crystal structure prediction and solid-state 1H NMR spectroscopy. (United States)

    Baias, Maria; Widdifield, Cory M; Dumez, Jean-Nicolas; Thompson, Hugh P G; Cooper, Timothy G; Salager, Elodie; Bassil, Sirena; Stein, Robin S; Lesage, Anne; Day, Graeme M; Emsley, Lyndon


    A protocol for the ab initio crystal structure determination of powdered solids at natural isotopic abundance by combining solid-state NMR spectroscopy, crystal structure prediction, and DFT chemical shift calculations was evaluated to determine the crystal structures of four small drug molecules: cocaine, flutamide, flufenamic acid, and theophylline. For cocaine, flutamide and flufenamic acid, we find that the assigned (1)H isotropic chemical shifts provide sufficient discrimination to determine the correct structures from a set of predicted structures using the root-mean-square deviation (rmsd) between experimentally determined and calculated chemical shifts. In most cases unassigned shifts could not be used to determine the structures. This method requires no prior knowledge of the crystal structure, and was used to determine the correct crystal structure to within an atomic rmsd of less than 0.12 Å with respect to the known reference structure. For theophylline, the NMR spectra are too simple to allow for unambiguous structure selection.

  5. Travelling-wave amplitudes as solutions of the phase-field crystal equation (United States)

    Nizovtseva, I. G.; Galenko, P. K.


    The dynamics of the diffuse interface between liquid and solid states is analysed. The diffuse interface is considered as an envelope of atomic density amplitudes as predicted by the phase-field crystal model (Elder et al. 2004 Phys. Rev. E 70, 051605 (doi:10.1103/PhysRevE.70.051605); Elder et al. 2007 Phys. Rev. B 75, 064107 (doi:10.1103/PhysRevB.75.064107)). The propagation of crystalline amplitudes into metastable liquid is described by the hyperbolic equation of an extended Allen-Cahn type (Galenko & Jou 2005 Phys. Rev. E 71, 046125 (doi:10.1103/PhysRevE.71.046125)) for which the complete set of analytical travelling-wave solutions is obtained by the" xlink:href="RSTA20170202IM1"/> method (Malfliet & Hereman 1996 Phys. Scr. 15, 563-568 (doi:10.1088/0031-8949/54/6/003); Wazwaz 2004 Appl. Math. Comput. 154, 713-723 (doi:10.1016/S0096-3003(03)00745-8)). The general" xlink:href="RSTA20170202IM2"/> solution of travelling waves is based on the function of hyperbolic tangent. Together with its set of particular solutions, the general" xlink:href="RSTA20170202IM3"/> solution is analysed within an example of specific task about the crystal front invading metastable liquid (Galenko et al. 2015 Phys. D 308, 1-10 (doi:10.1016/j.physd.2015.06.002)). The influence of the driving force on the phase-field profile, amplitude velocity and correlation length is investigated for various relaxation times of the gradient flow. This article is part of the theme issue `From atomistic interfaces to dendritic patterns'.

  6. Experimental phasing for structure determination using membrane-protein crystals grown by the lipid cubic phase method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dianfan; Pye, Valerie E.; Caffrey, Martin, E-mail: [Trinity College Dublin, Dublin (Ireland)


    Very little information is available in the literature concerning the experimental heavy-atom phasing of membrane-protein structures where the crystals have been grown using the lipid cubic phase (in meso) method. In this paper, pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine labelling as applied to an integral membrane kinase crystallized in meso are described. An assay to assess cysteine accessibility for mercury labelling of membrane proteins is introduced. Despite the marked increase in the number of membrane-protein structures solved using crystals grown by the lipid cubic phase or in meso method, only ten have been determined by SAD/MAD. This is likely to be a consequence of the technical difficulties associated with handling proteins and crystals in the sticky and viscous hosting mesophase that is usually incubated in glass sandwich plates for the purposes of crystallization. Here, a four-year campaign aimed at phasing the in meso structure of the integral membrane diacylglycerol kinase (DgkA) from Escherichia coli is reported. Heavy-atom labelling of this small hydrophobic enzyme was attempted by pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine incorporation. Strategies and techniques for special handling are reported, as well as the typical results and the lessons learned for each of these approaches. In addition, an assay to assess the accessibility of cysteine residues in membrane proteins for mercury labelling is introduced. The various techniques and strategies described will provide a valuable reference for future experimental phasing of membrane proteins where crystals are grown by the lipid cubic phase method.

  7. Determining the solid phases hosting arsenic in Mekong Delta sediments (United States)

    Wucher, M.; Stuckey, J. W.; McCurdy, S.; Fendorf, S.


    The major river systems originating from the Himalaya deposit arsenic bearing sediment into the deltas of South and Southeast Asia. High rates of sediment and organic carbon deposition combined with frequent flooding leads to anaerobic processes that release arsenic into the pore-water. Arsenic concentrations in the groundwater of these sedimentary basins are often above the World Health Organization drinking water standard of 10 μg As L-1. As a result, 150 million people are at risk of chronic arsenic poisoning through water and rice consumption. The composition of the iron bearing phases hosting the arsenic in these deltaic sediments is poorly understood. Here we implemented a suite of selective chemical extractions to help constrain the types of arsenic bearing solid phases, which were complimented with synchrotron-based X-ray absorption spectroscopy and X-ray diffraction analyses to define the arsenic and iron mineralogy of the system. Sediment cores were collected in triplicate from a seasonally-inundated wetland in Cambodia at depths of 10, 50, 100, and 150 centimeters. We hypothesize that (i) arsenic will be predominantly associated with iron oxides, and (ii) the ratio of crystalline to amorphous iron oxides will increase with sediment depth (and age). We performed four selective extractions in parallel to quantify the various pools of arsenic. First, 1 M MgCl2 was used to extract electrostatically-bound arsenic (labile forms) from the sediment. Second, 1 M NaH2PO4 targeted strongly adsorbed arsenic. Third, 1 M HCl was used to liberated arsenic coprecipitated with amorphous Fe/Mn oxides, carbonates, and acid-volatile sulfides. Finally, a dithionite extraction was used to account for arsenic associated with reducible Fe/Mn oxides. Through this work, we identified the composition of the phases hosting arsenic at various depths through the soil profile, improving our understanding of how arsenic persists in the aquifer. In addition, defining the arsenic and

  8. [Applications of solid-phase microextraction technique in natural product analysis]. (United States)

    Wei, Ning-yi; Duan, Tian-xuan; Ma, Chang-hua


    Solid-phase microextraction is a new technique of analysis. It has many merits and expanse foreground. A Review of the principle, recent development and applications of solid-phase microextraction is given, focusing on natural product analysis, especially on Chinese traditional medicine. Twenty-nine references are cited in the paper.

  9. Competitive solid-phase immunoassay of gastrin in serum using time-resolved fluorometry

    DEFF Research Database (Denmark)

    Johnsen, Anders H; Assaad, Fahed N; Rehfeld, Jens F


    A competitive solid-phase assay for the measurement of gastrin in serum using time-resolved fluorescence was developed as an alternative to conventional radioimmunoassay (RIA) technology.......A competitive solid-phase assay for the measurement of gastrin in serum using time-resolved fluorescence was developed as an alternative to conventional radioimmunoassay (RIA) technology....

  10. 40 CFR 227.32 - Liquid, suspended particulate, and solid phases of a material. (United States)


    ... MATERIALS Definitions § 227.32 Liquid, suspended particulate, and solid phases of a material. (a) For the... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Liquid, suspended particulate, and solid phases of a material. 227.32 Section 227.32 Protection of Environment ENVIRONMENTAL PROTECTION...

  11. Facile synthesis of aliphatic isothiocyanates and thioureas on solid phase using peptide coupling reagents

    DEFF Research Database (Denmark)

    Boas, Ulrik; Andersen, Heidi Gertz; Christensen, Jørn B.


    Peptide coupling reagents can be used as versatile reagents for the formation of aliphatic isothiocyanates and thioureas on solid phase from the corresponding solid-phase anchored aliphatic primary amines. The formation of the thioureas is fast and highly chemoselective, and proceeds via formation...

  12. 1,2,4-Triazolium perfluorobutanesulfonate as an archetypal pure protic organic ionic plastic crystal electrolyte for all-solid-state fuel cells

    DEFF Research Database (Denmark)

    Luo, Jiangshui; Jensen, Annemette Hindhede; Brooks, Neil R.


    1,2,4-Triazolium perfluorobutanesulfonate (1), a novel, pure protic organic ionic plastic crystal (POIPC) with a wide plastic crystalline phase, has been explored as a proof-of-principle anhydrous proton conductor for all-solid-state high temperature hydrogen/air fuel cells. Its physicochemical...... properties, including thermal, mechanical, structural, morphological, crystallographic, spectral, and ion-conducting properties, as well as fuel cell performances, have been studied comprehensively in both fundamental and device-oriented aspects. With superior thermal stability, 1 exhibits crystal (phase III...... patterns further illustrate the structural changes. Electrochemical hydrogen pumping tests confirm the protonic nature of the ionic conduction observed in the lower plateau region. Finally, measurements of the open circuit voltages (OCVs) and the polarization curves of a dry hydrogen/air fuel cell prove...

  13. Novel materials and methods for solid-phase extraction and liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Ambrose, Diana [Iowa State Univ., Ames, IA (United States)


    This report contains a general introduction which discusses solid-phase extraction and solid-phase micro-extraction as sample preparation techniques for high-performance liquid chromatography, which is also evaluated in the study. This report also contains the Conclusions section. Four sections have been removed and processed separately: silicalite as a sorbent for solid-phase extraction; a new, high-capacity carboxylic acid functionalized resin for solid-phase extraction; semi-micro solid-phase extraction of organic compounds from aqueous and biological samples; and the high-performance liquid chromatographic determination of drugs and metabolites in human serum and urine using direct injection and a unique molecular sieve.

  14. The growth of a cubic, single phase, Cd 0.6Mn 0.4Te single crystal by the vertical gradient freeze method (United States)

    Azoulay, M.; Raizman, A.; Weingarten, R.; Shacham, H.; Feldstein, H.


    The growth of CdMnTe single crystals faces some difficulties due to the phase transition in the solid state at high temperatures, just after solidification. To overcome this problem, it has been suggested to grow the crystals from a Te-rich solution by the traveling heater method at a lower temperature than that of growth from the melt, or alternatively to grow the crystal from the melt at high axial thermal gradient near the interface. In this paper, we present for the first time the growth of cubic, single phase, CdxMn1-xTe single crystals by the vertical gradient freeze technique under a very low axial thermal gradient in the melt (3°C/cm) and high manganese content (x ≈ 40%). The solidification stage is characterized by a rapid cooling of the crystal through the phase transition temperature region, followed by annealing at about 800°C. The crystal exhibits a very high crystalline perfection, as measured by the double-crystal X-ray rocking curves with a full width at half maximum of 30 arc sec and low optical losses of about 1 dB/mm between 650 and 820 nm with λ-cutoff at 630 nm. Further magneto-optical properties are currently examined for a possible application in devices.

  15. Supported imidazolium ionic liquid phases: a new material for solid-phase extraction. (United States)

    Fontanals, Núria; Ronka, Sylwia; Borrull, Francesc; Trochimczuk, Andrzej W; Marcé, Rosa M


    This study reports a material that is based on the concept of ionic liquid analogue: a slightly crosslinked polymer-supported imidazolium trifluoroacetate salt (IL-CF(3)COO(-)) that favorably combines the properties of ionic liquids (ILs) and the advantages of a solid support. The ionic liquid-supported material was evaluated for the first time as a solid-phase extraction (SPE) sorbent for selectively and quantitatively extracting pharmaceuticals from aqueous samples. The novel IL-CF(3)COO(-) was evaluated under reversed-phase (RP), weak anion exchange (WAX), strong anion exchange (SAX) and strong cation exchange (SCX) SPE procedures, and we found that SAX conditions are the most suitable for investigating the behaviour of the IL-CF(3)COO(-) material. Under SAX conditions, the IL-CF(3)COO(-) material was capable of selectively and quantitatively extracting a group of acidic compounds from aqueous samples, while washing basic analytes that were also present in the sample. The SPE method using IL-CF(3)COO(-) material was used to analyse 1000 ml of different aqueous samples (ultrapure, tap and river) with complete recovery of the acidic compounds studied. Moreover, the method provided clean chromatogram and high recoveries when percolating complex real samples, such as 1000 ml of river water and 250 ml of effluent wastewater from a sewage treatment plant spiked at low levels with the analytes studied.

  16. Ginzburg-Landau theory for the solid-liquid interface of bcc elements. II - Application to the classical one-component plasma, the Wigner crystal, and He-4 (United States)

    Zeng, X. C.; Stroud, D.


    The previously developed Ginzburg-Landau theory for calculating the crystal-melt interfacial tension of bcc elements to treat the classical one-component plasma (OCP), the charged fermion system, and the Bose crystal. For the OCP, a direct application of the theory of Shih et al. (1987) yields for the surface tension 0.0012(Z-squared e-squared/a-cubed), where Ze is the ionic charge and a is the radius of the ionic sphere. Bose crystal-melt interface is treated by a quantum extension of the classical density-functional theory, using the Feynman formalism to estimate the relevant correlation functions. The theory is applied to the metastable He-4 solid-superfluid interface at T = 0, with a resulting surface tension of 0.085 erg/sq cm, in reasonable agreement with the value extrapolated from the measured surface tension of the bcc solid in the range 1.46-1.76 K. These results suggest that the density-functional approach is a satisfactory mean-field theory for estimating the equilibrium properties of liquid-solid interfaces, given knowledge of the uniform phases.

  17. Dissolution properties, solid-state transformation and polymorphic crystallization: progesterone case study. (United States)

    Araya-Sibaja, Andrea Mariela; Paulino, Amarilis Scremin; Rauber, Gabriela Schneider; Campos, Carlos Eduardo Maduro; Cardoso, Simone Gonçalves; Monti, Gustavo Alberto; Heredia, Valeria; Bianco, Ismael; Beltrano, Dante; Cuffini, Silvia Lucia


    Progesterone is a natural steroid hormone and a poor soluble drug which presents two polymorphs (forms 1 and 2). Different methods to obtain form 2 were tested and a complete solid-state characterization of both polymorphs (forms 1 and 2) was conducted. X-ray powder diffraction, hot stage microscopy, Fourier transform infrared, dispersive Raman, (13)C solid-state nuclear magnetic resonance spectroscopy, thermal analysis, scanning electron microscopy techniques and intrinsic dissolution rates (IDR) were applied to investigate physical-chemical and dissolution properties of these two polymorphs. Form 2 was obtained from diluted solutions and from melting after cooling at room temperature. Form 1 was obtained from concentrated solutions and, a mixture of both polymorphs was crystallized from intermediate solutions. The crystal habit was not a distinctive characteristic of each polymorph. The effect of mechanical stress was evaluated in the metastable polymorph (form 2). We observed that grinding form 2 produced seeds of form 1 that induced the transformation of form 2 into form 1 at high temperature. The polymorphic quantification from XRD patterns of ground samples were carried out by the Rietveld method. After grinding and at room temperature conditions (∼25 °C), it was observed the transformation of 17% of form 2 into form 1 in 10 days.

  18. Ultrarapid mutation detection by multiplex, solid-phase chemical cleavage

    Energy Technology Data Exchange (ETDEWEB)

    Rowley, G.; Saad, S.; Giannelli, F.; Green, P.M. [Guy`s & St. Thomas`s Hospitals, London (United Kingdom)


    The chemical cleavage of mismatches in heteroduplexes formed by probe and test DNA detects and locates any sequence change in long DNA segments ({approximately}1.8 kb), and its efficiency has been well tested in the analysis of both average (e.g., coagulation factor IX) and large, complex genes (e.g., coagulation factor VIII and dystrophin). In the latter application RT/PCR products allow the examination of all essential sequences of the gene in a minimum number of reactions. We use two specific chemical reactants (hydroxylamine and osmium tetroxide) and piperidine cleavage of the above procedure to develop a very fast mutation screening method. This is based on: (1) 5{prime} or internal fluorescent labeling to allow concurrent screening of three to four DNA fragments and (2) solid-phase chemistry to use a microliter format and reduce the time required for the procedure, from amplification of sequence to gel loading inclusive, to one person-working-day. We test the two variations of the method, one entailing 5{prime} labeling of probe DNA and the other uniform labeling of both probe and target DNA, by detecting 114 known hemophilia B (coagulation factor IX) mutations and by analyzing 129 new patients. Uniform labeling of both probe and target DNA prior to formation of the heteroduplexes leads to almost twofold redundancy in the ability to detect mutations. Alternatively, the latter procedure may offer very efficient though less than 100% screening for sequence changes with only hydroxylamine. The full method with two chemical reactions (hydroxylamine and osmium tetroxide) should allow one person to screen with virtually 100% accuracy more than 300 kb of sequence in three ABI 373 gels in 1 day. 26 refs., 7 figs., 1 tab.

  19. Crystal Phases Formed in a CaO-Fe2O3 System Under a High Cooling Rate in Air (United States)

    Kashiwaya, Yoshiaki


    A CaO-Fe2O3 system is a fundamental binary system for the iron ore sintering process. Although the basic reactions have been investigated since the 1960s, melting and solidification caused by the combustion of coke results in an unstable state owing to extreme temperature variations. In this study, using a hot thermocouple method, samples of 10 pct CaO-90 pct Fe2O3 and 20 pct CaO-80 pct Fe2O3 were melted on a thermocouple and quenched with several techniques. The obtained samples were precisely examined by XRD. It was found that the sample containing 10 pct CaO-90 pct Fe2O3 changed to 10 pct CaO-13 pct FeO-77 pct Fe2O3 under an oxygen partial pressure ( P_{{{O}2 }} ) of 0.21 during melting. For the 10 pct CaO sample, the crystal phases found at a low cooling rate (509 K/s) were WFss, C4WF8 (C: CaO, W: FeO, F: Fe2O3), and C2W4F9. When the sample composition was 20 pct CaO, the precipitated crystal phases were C4WF4, C4F7, and C4WF8. On the other hand, the crystal phases for high cooling rates (1590 and 7900 K/s) with 10 pct CaO were WFss (solid solution of WF and F), F, and C2W4F9. The formation of the equilibrium phases WFss, F, C4WF4, and C4WF8 can be understood by examining the isothermal section of the phase diagrams, while the unstable phases C2W4F9 and C4F7 are discussed on the basis of the reactions under an equilibrium state.

  20. Crystal Phases Formed in a CaO-Fe2O3 System Under a High Cooling Rate in Air (United States)

    Kashiwaya, Yoshiaki


    A CaO-Fe2O3 system is a fundamental binary system for the iron ore sintering process. Although the basic reactions have been investigated since the 1960s, melting and solidification caused by the combustion of coke results in an unstable state owing to extreme temperature variations. In this study, using a hot thermocouple method, samples of 10 pct CaO-90 pct Fe2O3 and 20 pct CaO-80 pct Fe2O3 were melted on a thermocouple and quenched with several techniques. The obtained samples were precisely examined by XRD. It was found that the sample containing 10 pct CaO-90 pct Fe2O3 changed to 10 pct CaO-13 pct FeO-77 pct Fe2O3 under an oxygen partial pressure ( P_{{{O}2 }} ) of 0.21 during melting. For the 10 pct CaO sample, the crystal phases found at a low cooling rate (509 K/s) were WFss, C4WF8 (C: CaO, W: FeO, F: Fe2O3), and C2W4F9. When the sample composition was 20 pct CaO, the precipitated crystal phases were C4WF4, C4F7, and C4WF8. On the other hand, the crystal phases for high cooling rates (1590 and 7900 K/s) with 10 pct CaO were WFss (solid solution of WF and F), F, and C2W4F9. The formation of the equilibrium phases WFss, F, C4WF4, and C4WF8 can be understood by examining the isothermal section of the phase diagrams, while the unstable phases C2W4F9 and C4F7 are discussed on the basis of the reactions under an equilibrium state.

  1. Biological treatment of soils contaminated with hydrophobic organics using slurry and solid phase techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cassidy, D.P.; Irvine, R.L. [Univ. of Notre Dame, IN (United States)


    Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurry is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bioslurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay load contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the ate and extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies.

  2. Atomically Phase-Matched Second-Harmonic Generation in a 2D Crystal (United States)


    OPEN ORIGINAL ARTICLE Atomically phase-matched second-harmonic generation in a 2D crystal Mervin Zhao1,2,*, Ziliang Ye1,2,*, Ryuji Suzuki3,4,*, Yu...arising from a single atomic layer, where the SH light elucidated important information such as the grain boundaries and electronic structure in these ultra...intensity on layer number as a result of atomically phase-matched nonlinear dipoles in layers of the 3R crystal that constructively interfere. By

  3. The second order phase transition in Sn2P2S6 crystals: anharmonic oscillator model

    Directory of Open Access Journals (Sweden)

    Yu.M. Vysochanskii


    Full Text Available Statistical theory for ferroelectrics based on triple well anharmonic potential was used for the case of structural second order phase transition in Sn2P2S6 crystals. Parameters of effective Hamiltonian of the model were estimated using available experimental data. These findings confirm the assumption that the phase transition in these crystals is located in crossover region between order-disorder and displacive type, and very closely to tricritical point.

  4. Neurotrophic peptide aldehydes: Solid phase synthesis of fellutamide B and a simplified analog


    Schneekloth, John S.; John L Sanders; Hines, John; Crews, Craig M.


    A combination of solid phase and solution phase synthetic methods have been used to complete the total synthesis of the neurotrophic lipopeptide aldehyde fellutamide B (2). The β-hydroxy aliphatic tail was prepared by regioselective reductive opening of a cyclic sulfate, and later coupled to a solid phase resin. The synthetic compound was then examined in cytotoxicity and nerve growth factor (NGF) induction assays. A simplified analog of fellutamide B also showed activity.

  5. Precipitation in solid solution and structural transformations in single crystals of high rhenium ruthenium-containing nickel superalloys at high-temperature creep

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.A.; Petrushin, N.V.; Zaitsev, D.V.; Treninkov, I.A.; Filonova, E.V. [All-Russian Scientific Research Institute of Aviation Materials (VIAM), Moscow (Russian Federation)


    The phase composition and structure of single crystals of two superalloys (alloy 1 and alloy 2) were investigated in this work. For alloy 1 (Re - 9 wt%) the kinetics of precipitation in solid solution at heat treatment (HT) was investigated. TEM and X-Ray examinations have revealed that during HT rhombic phase (R-phase) precipitation (Immm class (BCR)) occurs. The TTT diagram is plotted, it contains the time-temperature area of the existence of R-phase particles. The element content of R-phase is identified (at. %): Re- 51.5; Co- 23.5; Cr- 14.8; Mo- 4.2; W- 3.3; Ta- 2.7. For alloy 2 (Re - 6.5 wt %, Ru - 4 wt %) structural transformations at high-temperature creep are investigated. By dark-field TEM methods it is established, that in alloy 2 the additional phase with a rhombic lattice is formed during creep. Particles of this phase precipitate in {gamma}-phase and their quantity increases during high-temperature creep. It is revealed that during creep 3-D dislocation network is formed in {gamma}-phase. At the third stage of creep the process of inversion structure formation is observed in the alloy, i.e. {gamma}'-phase becomes a matrix. Thus during modeling creep the volume fraction of {gamma}'-phase in the samples increases from 30% (at creep duration of 200 hrs) up to 55% (at 500 hrs). The processes of structure formation in Re and Ru-containing nickel superalloys are strongly affected by decomposition of solid solution during high-temperature creep that includes precipitation of additional TCP-phases. (orig.)

  6. Optical properties of Pb-based aggregated phases in CsBr crystal

    Energy Technology Data Exchange (ETDEWEB)

    Voloshinovskii, A. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Myagkota, S. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Garapyn, I. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Stryganyuk, G. [Ivan Franko National University of Lviv, 8 Kyryla i Mefodiya Str., 79005 Lviv (Ukraine); Rodnyi, P. [St. Petersburg State Polytechnical University, 29 Polyteknicheskaya Str., 195251 St. Petersburg (Russian Federation); Eijk, C.W.E. van [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)]. E-mail:


    The emission and excitation spectra as well as luminescence decay kinetics of a CsBr:Pb (1.0mol%) crystal have been measured under pulsed synchrotron radiation excitation. The heat-treated ({approx}200 deg. C) crystal shows evidence of single lead centres and aggregated phases such as CsPbBr3 nanocrystals. The latter have been identified from comparison of the spectral-kinetic characteristics of the CsPbBr3 aggregated phases and single crystals. The process of energy transfer from the host to the aggregates is considered.

  7. Theoretical phase diagrams for [N(CD3)4]2ZnCl4 crystal (United States)

    Sannikov, D. G.


    A theoretical phase diagram of [N(CD3)4]2ZnCl4 crystal is constructed in the plane of two thermodynamic-potential coefficients. The orientation of the temperature ( T) and pressure ( P) axes is chosen in the diagram. The first diagram is used as a basis to construct the second theoretical T-P phase diagram, expanded to the region of weak negative pressures for nondeuterated [N(CH3)4]2ZnCl4 crystal. It is suggested that this region can be observed for deuterated [N(CD3)4]2ZnCl4 crystal.

  8. Prism-coupled Cherenkov phase-matched terahertz wave generation using a DAST crystal. (United States)

    Suizu, Koji; Shibuya, Takayuki; Uchida, Hirohisa; Kawase, Kodo


    Terahertz (THz) wave generation based on nonlinear frequency conversion is a promising method for realizing a tunable monochromatic high-power THz-wave source. Unfortunately, many nonlinear crystals have strong absorption in the THz frequency region. This limits efficient and widely tunable THz-wave generation. The Cherenkov phase-matching method is one of the most promising techniques for overcoming these problems. Here, we propose a prism-coupled Cherenkov phase-matching (PCC-PM) method, in which a prism with a suitable refractive index at THz frequencies is coupled to a nonlinear crystal. This has the following advantages. Many crystals can be used as THz-wave emitters; the phase-matching condition inside the crystal does not have to be observed; the absorption of the crystal does not prevent efficient generation of radiation; and pump sources with arbitrary wavelengths can be employed. Here we demonstrate PCC-PM THz-wave generation using the organic crystal 4-dimethylamino-N-metyl-4-stilbazolium tosylate (DAST) and a Si prism coupler. We obtain THz-wave radiation with tunability of approximately 0.1 to 10 THz and with no deep absorption features resulting from the absorption spectrum of the crystal. The obtained spectra did not depend on the pump wavelength in the range 1300 to 1450 nm. This simple technique shows promise for generating THz radiation using a wide variety of nonlinear crystals.

  9. Solid phase extraction and determination of carbamate pesticides in water samples by reverse-phase HPLC

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Tovar, J.; Santos-Delgado, M.J. [Departamento de Quimica Analitica, Facultad de ciencias Quimicas, Universidad Complutense de Madrid (Spain)


    Solid phase extraction. SPE. using C{sub 1}8 bonded silica cartridges for trace amounts determination of carbaryl, propoxur, thiram, propham and methiocarb in water samples was studied and the breakthrough volume of the cartridges was established. The high enrichment factor and large injection volume admissible in the isocratic reverse-phase HPLC system allows pesticides determination with UV detection at 22o nm even at a concentration lower than 0.05 mug/L. Purified tap natural and underground water samples were spiked with carbamate pesticides in the concentration range 0.16-16.0 mug/L. Large volumes of samples (up to 2L) were passed through available C{sub 1}8, cartridges and eluted with acetonitrile. The preconcentrated samples were analyzed by HPLC using a Spherisorb ODS column with a 42.58 acetonitrile-water mobile phase. From replicate samples, recovery for the pesticides ranged from 79.0 to 103.7% except for thiran which is not retained. Tehe relative standard deviation (n=4 at 0.16 to 1.61 mug/L concetration level) range from 1.1 to 6.8%. (Author) 14 refs.

  10. Monoolein Lipid Phases as Incorporation and Enrichment Materials for Membrane Protein Crystallization (United States)

    Wallace, Ellen; Dranow, David; Laible, Philip D.; Christensen, Jeff; Nollert, Peter


    The crystallization of membrane proteins in amphiphile-rich materials such as lipidic cubic phases is an established methodology in many structural biology laboratories. The standard procedure employed with this methodology requires the generation of a highly viscous lipidic material by mixing lipid, for instance monoolein, with a solution of the detergent solubilized membrane protein. This preparation is often carried out with specialized mixing tools that allow handling of the highly viscous materials while minimizing dead volume to save precious membrane protein sample. The processes that occur during the initial mixing of the lipid with the membrane protein are not well understood. Here we show that the formation of the lipidic phases and the incorporation of the membrane protein into such materials can be separated experimentally. Specifically, we have investigated the effect of different initial monoolein-based lipid phase states on the crystallization behavior of the colored photosynthetic reaction center from Rhodobacter sphaeroides. We find that the detergent solubilized photosynthetic reaction center spontaneously inserts into and concentrates in the lipid matrix without any mixing, and that the initial lipid material phase state is irrelevant for productive crystallization. A substantial in-situ enrichment of the membrane protein to concentration levels that are otherwise unobtainable occurs in a thin layer on the surface of the lipidic material. These results have important practical applications and hence we suggest a simplified protocol for membrane protein crystallization within amphiphile rich materials, eliminating any specialized mixing tools to prepare crystallization experiments within lipidic cubic phases. Furthermore, by virtue of sampling a membrane protein concentration gradient within a single crystallization experiment, this crystallization technique is more robust and increases the efficiency of identifying productive crystallization

  11. Crystallization Mechanism and Phase Transition Properties of W-doped VO2 Synthesized by Hydrothermal Method

    Directory of Open Access Journals (Sweden)

    LI Yao


    Full Text Available VO2 sol was firstly prepared using vanadyl sulfate as a vanadium source by precipitation-peptization method. Then tungsten(W doping vanadium dioxide(W-VO2 was prepared by hydrothermal crystallization of prepared sol with the presence of ammonium metatungstate. The morphologies, crystal structure of the as-prepared samples and phase transition properties were studied by X-ray diffraction(XRD, field emission scanning electron microscope(FESEMand differential scanning calorimetry(DSC analysis. The results indicate that rod-like W-VO2(B crystal with length of 1-2μm and radius of 100-200nm is firstly formed during hydrothermal treatment for 4-48h at 280℃, then the rod-like crystal dissolves gradually and sheet-like or snowflake-like crystal is formed with the phase transition from W-VO2(B to W-VO2(M and eventually, the W-VO2(M crystals can further grow up while the W-VO2(B gradually dissolves; the phase transition temperature of VO2 decreases with the increase in W doping content, and the phase transition temperature of W-VO2(M reduces to about 28℃ when the nominal dopant concentration is 6.0%(atom fraction.The "nucleation-growth-transformation-ripening" mechanism is proposed as the formation mechanism based on the hydrothermal crystallization and morphological evolution process of W-VO2(M.

  12. Phase diagrams of mixtures of a polymer and a cholesteric liquid crystal under an external field. (United States)

    Matsuyama, Akihiko


    We present a mean field theory to describe phase behaviors in mixtures of a polymer and a cholesteric liquid crystal under an external magnetic or electric field. Taking into account a chiral coupling between a polymer and a liquid crystal under the external field, we examine twist-untwist phase transitions and phase separations in the mixtures. It is found that a cholesteric-nematic phase transition can be induced by not only the external field but also concentration and temperature. Depending on the strength of the external field, we predict cholesteric-paranematic (Ch+pN), nematic-paranematic (N+pN), cholesteric-nematic (Ch+N) phase separations, etc., on the temperature-concentration plane. We also discuss mixtures of a non-chiral nematic liquid crystal and a chiral dopant.

  13. Phase transitions in Cs5(HSO4)2(H2PO4)3 crystal (United States)

    Grebenev, V. V.; Makarova, I. P.; Ksenofontov, D. A.; Komornikov, V. A.; Dmitricheva, E. V.


    The symmetry (sp. gr. I 3 d) and lattice parameters have been determined for the first time for Cs5(H2SO4)2(H2PO4)3 crystals in the temperature range from 172 to 390 K. The thermal and optical properties of crystals, as well as their conductivity, have been investigated at elevated temperatures. It is shown that a crystal heated to T = 365 K undergoes a phase transition with symmetry lowering to the tetragonal phase (with the parameters a = 4.965(1) Å and c = 5.016(1) Å), while at T ≈ 390 K a phase transition to the cubic phase is presumably observed. With a decrease in temperature, a phase transition without a change in symmetry occurs at T = 240 K.

  14. The growth and tensile deformation behavior of the silver solid solution phase with zinc

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiaqi, E-mail: [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States); Lee, Chin C. [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States)


    The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

  15. Phase transitions in KDP crystals with the complex organic and inorganic impurities

    Directory of Open Access Journals (Sweden)



    Full Text Available In this paper we present the results of the study of dielectric and thermal properties of KDP crystals doped with different complex organic and inorganic molecules which decorate different (pyramidal or prismatic crystal growth sectors. It is shown that the properties of stained and transparent parts of the crystal in comparison with the corresponding parts of the nominally pure crystal are different for KDP crystals grown by means of traditional (slow and rapid growth technique. The difference of the domain contribution into dielectric constant of the polar phase and its characteristic hysteresis in pure and dyed crystals, transition temperature position, form of the specific heat anomaly are presented and analyzed. The most probable model of incorporation of the complex impurity molecules into KDP structure is proposed.

  16. Intramolecular London Dispersion Interaction Effects on Gas-Phase and Solid-State Structures of Diamondoid Dimers. (United States)

    Fokin, Andrey A; Zhuk, Tatyana S; Blomeyer, Sebastian; Pérez, Cristóbal; Chernish, Lesya V; Pashenko, Alexander E; Antony, Jens; Vishnevskiy, Yury V; Berger, Raphael J F; Grimme, Stefan; Logemann, Christian; Schnell, Melanie; Mitzel, Norbert W; Schreiner, Peter R


    The covalent diamantyl (C 28 H 38 ) and oxadiamantyl (C 26 H 34 O 2 ) dimers are stabilized by London dispersion attractions between the dimer moieties. Their solid-state and gas-phase structures were studied using a multitechnique approach, including single-crystal X-ray diffraction (XRD), gas-phase electron diffraction (GED), a combined GED/microwave (MW) spectroscopy study, and quantum chemical calculations. The inclusion of medium-range electron correlation as well as the London dispersion energy in density functional theory is essential to reproduce the experimental geometries. The conformational dynamics computed for C 26 H 34 O 2 agree well with solution NMR data and help in the assignment of the gas-phase MW data to individual diastereomers. Both in the solid state and the gas phase the central C-C bond is of similar length for the diamantyl [XRD, 1.642(2) Å; GED, 1.630(5) Å] and the oxadiamantyl dimers [XRD, 1.643(1) Å; GED, 1.632(9) Å; GED+MW, 1.632(5) Å], despite the presence of two oxygen atoms. Out of a larger series of quantum chemical computations, the best match with the experimental reference data is achieved with the PBEh-3c, PBE0-D3, PBE0, B3PW91-D3, and M06-2X approaches. This is the first gas-phase confirmation that the markedly elongated C-C bond is an intrinsic feature of the molecule and that crystal packing effects have only a minor influence.

  17. Controlling Interface States in 1D Photonic Crystals by tuning Bulk Geometric Phases

    CERN Document Server

    Gao, Wensheng; Chen, Baojie; Pun, Edwin Y B; Chan, C T; Tam, Wing Yim


    Interface states in photonic crystals usually require defects or surface/interface decorations. We show here that one can control interface states in 1D photonic crystals through the engineering of geometrical phase such that interface states can be guaranteed in even or odd, or in all photonic bandgaps. We verify experimentally the designed interface states in 1D multilayered photonic crystals fabricated by electron beam vapor deposition. We also obtain the geometrical phases by measuring the reflection phases at the bandgaps of the PCs and achieve good agreement with the theory. Our approach could provide a platform for the design of using interface states in photonic crystals for nonlinear optic, sensing, and lasing applications

  18. Crystal Phase Quantum Well Emission with Digital Control

    NARCIS (Netherlands)

    Assali, S.; Lähnemann, J.; Vu, TTT; Jöns, K.D.; Gagliano, L; Verheijen, M. A.; Akopian, N.; Bakkers, E.P.A.M.; Haverkort, J. E.M.


    One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the

  19. Crystal phases of calcium carbonate within otoliths of Cyprinus ...

    African Journals Online (AJOL)

    Significant differences of the dimensions of crystalline cells of vaterites exist between these two localities, which reveals that crystal structure of vaterite polymorphs seem sensitive to water quality and water environment, its crystalline cell dimensions might be a potential proxy for monitoring the change of water quality.

  20. Salts and Co-crystals of Theobromine and their phase ...

    Indian Academy of Sciences (India)

    of stability, these salts transformed to theobromine within 1 h of dissolution in water. Remarkably, the besylate and tosylate salts are 88 and 58 times more soluble than theobromine, but they dissociated within 1 h. In contrast, theobromine co-crystals with gallic acid, anthranilic acid and 5-chlorosalicylic acid were found to be.

  1. Dissolution of Danazol Amorphous Solid Dispersions: Supersaturation and Phase Behavior as a Function of Drug Loading and Polymer Type. (United States)

    Jackson, Matthew J; Kestur, Umesh S; Hussain, Munir A; Taylor, Lynne S


    Amorphous solid dispersions (ASDs) are of great interest as enabling formulations because of their ability to increase the bioavailability of poorly soluble drugs. However, the dissolution of these formulations under nonsink dissolution conditions results in highly supersaturated drug solutions that can undergo different types of phase transitions. The purpose of this study was to characterize the phase behavior of solutions resulting from the dissolution of model ASDs as well as the degree of supersaturation attained. Danazol was chosen as a poorly water-soluble model drug, and three polymers were used to form the dispersions: polyvinylpyrrolidone (PVP), hydroxypropylmethyl cellulose (HPMC), and hydroxypropylmethyl cellulose acetate succinate (HPMCAS). Dissolution studies were carried out under nonsink conditions, and solution phase behavior was characterized using several orthogonal techniques. It was found that liquid-liquid phase separation (LLPS) occurred following dissolution and prior to crystallization for most of the dispersions. Using flux measurements, it was further observed that the maximum attainable supersaturation following dissolution was equivalent to the amorphous solubility. The dissolution of the ASDs led to sustained supersaturation, the duration of which varied depending on the drug loading and the type of polymer used in the formulation. The overall supersaturation profile observed thus depended on a complex interplay between dissolution rate, polymer type, drug loading, and the kinetics of crystallization.

  2. α-Azido Acids in Solid-Phase Peptide Synthesis: Compatibility with Fmoc Chemistry and an Alternative Approach to the Solid Phase Synthesis of Daptomycin Analogs. (United States)

    Lohani, Chuda Raj; Rasera, Benjamin; Scott, Bradley; Palmer, Michael; Taylor, Scott D


    α-Azido acids have been used in solid phase peptide synthesis (SPPS) for almost 20 years. Here we report that peptides bearing an N-terminal α-azidoaspartate residue undergo elimination of an azide ion when treated with reagents that are commonly used for removing the Fmoc group during SPPS. We also report an alternative solid-phase route to the synthesis of an analog of daptomycin that uses a reduced number of α-azido amino acids and without elimination of an azide ion.

  3. Universality and criticality of a second-order granular solid-liquid-like phase transition. (United States)

    Castillo, Gustavo; Mujica, Nicolás; Soto, Rodrigo


    We experimentally study the critical properties of the nonequilibrium solid-liquid-like transition that takes place in vibrated granular matter. The critical dynamics is characterized by the coupling of the density field with the bond-orientational order parameter Q(4), which measures the degree of local crystallization. Two setups are compared, which present the transition at different critical accelerations as a result of modifying the energy dissipation parameters. In both setups five independent critical exponents are measured, associated to different properties of Q(4): the correlation length, relaxation time, vanishing wavenumber limit (static susceptibility), the hydrodynamic regime of the pair correlation function, and the amplitude of the order parameter. The respective critical exponents agree in both setups and are given by ν(⊥)=1,ν(∥)=2,γ=1,η≈0.6-0.67, and β=1/2, whereas the dynamical critical exponent is z=ν(∥)/ν(⊥)=2. The agreement on five exponents is an exigent test for the universality of the transition. Thus, while dissipation is strictly necessary to form the crystal, the path the system undergoes toward the phase separation is part of a well-defined universality class. In fact, the local order shows critical properties while density does not. Being the later conserved, the appropriate model that couples both is model C in the Hohenberg and Halperin classification. The measured exponents are in accord with the nonequilibrium extension to model C if we assume that α, the exponent associated in equilibrium to the specific heat divergence but with no counterpart in this nonequilibrium experiment, vanishes.

  4. Thermodynamic consistency and fast dynamics in phase field crystal modeling


    Cheng, Mowei; Cottenier, Stefaan; Emmerich, Heike


    A general formulation is presented to derive the equation of motion and to demonstrate thermodynamic consistency for several classes of phase field models at once. It applies to models with a conserved phase field, describing either uniform or periodic stable states, and containing slow as well as fast thermodynamic variables. The approach is based on an entropy functional formalism previously developed in the context of phase field models for uniform states [P. Galenko and D. Jou, Phys. Rev....

  5. Crystallization Kinetics of GeSbTe Phase-Change Nanoparticles Resolved by Ultrafast Calorimetry

    NARCIS (Netherlands)

    Chen, Bin; Brink, ten Gert; Palasantzas, Georgios; Kooi, Bart J.


    Although nanostructured phase-change materials (PCMs) are considered as the building blocks of next-generation phase-change memory and other emerging optoelectronic applications, the kinetics of the crystallization, the central property in switching, remains ambiguous in the high-temperature regime.

  6. Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility (User’s Manual) (United States)


    GUIDANCE DOCUMENT Demonstration and Evaluation of Solid Phase Microextraction For the Assessment of Bioavailability and Contaminant Mobility...Demonstration and Evaluation of Solid Phase Microextraction for the Assessment of Bioavailability and Contaminant Mobility ER-200624Danny R. measurement of sediment pore water concentrations with solid phase microextraction using polydimethyl siloxane as the extractant. The method

  7. Adsorption of the Three-phase Emulsion on Various Solid Surfaces. (United States)

    Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo


    The present study investigates the adsorption of the three-phase emulsion on various solid/water interfaces. Vesicles can be used as emulsifiers in the three-phase emulsions and act as an independent phase unlike the surfactant used in conventional emulsions; therefore, it is expected that the three-phase emulsion formed by the adhesion of vesicles to the oil/water interface will adsorb on various solid/water interfaces. The cationic three-phase emulsion was prepared to encourage emulsion adsorption on negatively charged solid substrates in water. The emulsifier polyoxyethylene-(10) hydrogenated castor oil was rendered cationic by mixing with the surfactant cetyltrimethylammonium bromide and then used to prepare the cationic three-phase emulsion of hexadecane-in-water. Three solid substrates (silicon, glass, and copper) were dipped in the cationic emulsion and the emulsion was found to adsorb on the solid substrates while maintaining its structure. The amount of hexadecane adsorbed on the various surfaces was investigated by gas chromatography and found to increase with increasing hexadecane concentration in the emulsion and eventually plateaued just like molecular adsorption. The maximum surface coverage of the emulsion on the substrates was approximately 80%. However, even the equivalent nonionic three-phase emulsion was found to adsorb on the three solid surfaces. This was attributed to a novel mechanism of irreversible adhesion via the van der Waals attractive force.

  8. Liquid Crystals of Dendron-Like Pt Complexes Processable Into Nanofilms Dendrimers. Phase 2. Cholesteric Liquid Crystal Glass Platinum Acetylides (United States)


    Std. Z39.18 Final Report Liquid Crystals of Dendron-Like Pt Complexes Processable Into Nanofilms. Dendrimers Eduardo pack and also the presence of a polar group. Figure 4. Summary of phase behavior. DENDRIMERS New Denrimers. The synthesis...purification and some spectral characteristics of the new dendrimers shown in Fig 5 were reported in AFOSR FA9550-11-1-0169, May, 2013. Further

  9. Crystal growth of an organic non-linear optical material from the vapour phase

    CERN Document Server

    Hou, W


    Due to the potential applications of organic non-linear optical materials in the areas of optical processing and communication, the investigation of the crystal growth of new organic NLO materials has been an active field for the last 20 years. For such uses it is necessary to produce single crystals of high quality and perfection, free of strain and defects. When crystals are grown from the solution and the melt, solvent and the decomposition component in the melt can introduce impurities and imperfection to the as-grown crystals. For crystals grown from vapour phase, in the absence of the solvent, this cannot occur and the method promises to yield single crystals of higher quality. Despite this attraction, little attention has been paid to the vapour phase growth of organic NLO crystals. It was with this in mind that the following investigation was carried out. Using Methyl p-hydroxybenzoate (p-MHB), a potential organic NLO material, a comparison investigation was made of its crystal growth from both the va...

  10. Phase nucleation and evolution mechanisms in heterogeneous solids (United States)

    Udupa, Anirudh

    Phase nucleation and evolution is a problem of critical importance in many applications. As the length scales are reduced, it becomes increasingly important to consider interfacial and micro-structural effects that can be safely ignored at larger length scales owing to randomness. The theory of phase nucleation has been addressed usually by the classical nucleation theory, which was originally derived for single component fluid systems, after making an assumption of equilibrium. The criterion has not been rigorously derived for solids, which are far from equilibrium due to dissipation by multiple physical drivers. In this thesis, a thermodynamically sound nucleation criterion is derived for systems with multiple interacting physical phenomena and multiple dissipating mechanisms. This is done, using the tools of continuum mechanics, by determining the change in free energy upon the introduction of a new nucleus into the system. The developed theory is demonstrated to be a generalization of the classical nucleation theory (CNT). The developed theory is then applied to the problem of electromigration driven void nucleation, a serious reliability concern for the microelectronics industry. The void grows and eventually severs the line making the chip nonfunctional. There are two classes of theories at present in the electromigration literature to address the problem of void nucleation, the vacancy supersaturation theory and the entropic dissipation theory, both of which are empirical and based on intuition developed from experimental observations. When the developed theory was applied to the problem of electromigration, it was found to be consistent with the vacancy supersaturation theory, but provided the correct energetic quantity, the chemical potential, which has contribution from both the vacancy concentration as well as the hydrostatic stress. An experiment, consisting of electromigration tests on serpentine lines, was developed to validate the developed

  11. Computerized Liquid Crystal Phase Identification by Neural Networks Analysis of Polarizing Microscopy Textures (United States)

    Karaszi, Zoltan; Konya, Andrew; Dragan, Feodor; Jakli, Antal; CPIP/LCI; CS Dept. of Kent State University Collaboration

    Polarizing optical microscopy (POM) is traditionally the best-established method of studying liquid crystals, and using POM started already with Otto Lehman in 1890. An expert, who is familiar with the science of optics of anisotropic materials and typical textures of liquid crystals, can identify phases with relatively large confidence. However, for unambiguous identification usually other expensive and time-consuming experiments are needed. Replacement of the subjective and qualitative human eye-based liquid crystal texture analysis with quantitative computerized image analysis technique started only recently and were used to enhance the detection of smooth phase transitions, determine order parameter and birefringence of specific liquid crystal phases. We investigate if the computer can recognize and name the phase where the texture was taken. To judge the potential of reliable image recognition based on this procedure, we used 871 images of liquid crystal textures belonging to five main categories: Nematic, Smectic A, Smectic C, Cholesteric and Crystal, and used a Neural Network Clustering Technique included in the data mining software package in Java ``WEKA''. A neural network trained on a set of 827 LC textures classified the remaining 44 textures with 80% accuracy.

  12. 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)


    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.

  13. Expanding the Applicability of Poly(Ionic Liquids) in Solid Phase Microextraction: Pyrrolidinium Coatings

    National Research Council Canada - National Science Library

    David J. S. Patinha; Liliana C. Tomé; Mehmet Isik; David Mecerreyes; Armando J. D. Silvestre; Isabel M. Marrucho


    Crosslinked pyrrolidinium-based poly(ionic liquids) (Pyrr-PILs) were synthesized through a fast, simple, and solventless photopolymerization scheme, and tested as solid phase microextraction (SPME) sorbents...


    Two commercially available solid phase microextractions (SPME) fibers, polyacrylate and carboxem/polydimethylsiloxane (PDMS), were evaluated for their ability to extract hydrophilic compounds from drinking water. Conditions, such as desorption time, desorption temperature, sample...

  15. Evaluation of a Solid Phase DNA Binding Matrix for Downstream PCR Analysis

    National Research Council Canada - National Science Library

    Bader, Douglas E; Fisher, Glen R; Stratilo, Chad W


    A commercially available solid-phase DNA binding matrix (FTA cards) was evaluated for its ability to capture and release DNA for downstream gene amplification and detection assays using polymerase chain reaction (PCR...

  16. Diffusion-Limited Kinetics of the Solution-Solid Phase Transition of Molecular Substances

    National Research Council Canada - National Science Library

    Dimiter N. Petsev; Kai Chen; Olga Gliko; Peter G. Vekilov


    For critical tests of whether diffusion-limited kinetics is an option for the solution-solid phase transition of molecular substances or whether they are determined exclusively by a transition state...

  17. Simplifying Solid-Phase Extraction Method Development: Exploring the Use of Software

    National Research Council Canada - National Science Library

    Jeremy S Bierman; Michael V Campognone


      Solid-phase extraction (SPE) is a popular sample preparation technique, valued by analysts working with complex matrices for its ability to specifically select for target compounds, concentrate samples, and perform a solvent switch...

  18. Utilizing ion-pairing hydrophilic interaction chromatography solid phase extraction for efficient glycopeptide enrichment in glycoproteomics

    DEFF Research Database (Denmark)

    Mysling, Simon; Palmisano, Giuseppe; Højrup, Peter


    Glycopeptide enrichment is a prerequisite to enable structural characterization of protein glycosylation in glycoproteomics. Here we present an improved method for glycopeptide enrichment based on zwitter-ionic hydrophilic interaction chromatography solid phase extraction (ZIC-HILIC SPE...

  19. Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles

    NARCIS (Netherlands)

    Zielinska, K.


    Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid

  20. Solid-phase micro-extraction in bioanalysis, exemplified by lidocaine determination

    NARCIS (Netherlands)

    de Jong, GJ; Koster, EHM


    Solid-phase micro-extraction (SPME) is a never sample preparation technique that can be used for gaseous, liquid or solid samples in conjunction with GC, HPLC or CE (e.g. [1]). The use of SPME for the analysis of drugs in biofluids is also becoming popular (e.g. [2]). The principle is that a fused

  1. The Pictet-Spengler reaction in solid-phase combinatorial chemistry

    DEFF Research Database (Denmark)

    Nielsen, Thomas E; Diness, Frederik; Meldal, Morten


    The Pictet-Spengler reaction is an important reaction for the generation of tetrahydro-beta-carbolines and tetrahydroisoquinoline ring systems, which exhibit a range of biological and pharmacological properties. This review covers the solid-phase Pictet-Spengler reaction, as employed in solid...

  2. A possible crystal defect mediated mechanism governing energy release in solid organic secondary explosives (United States)

    Henson, Bryan; Smilowitz, Laura


    Work has been ongoing in our group for several years to produce a global chemistry model of thermal ignition for the solid organic secondary explosive octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) valid over the entire temperature range of energetic response from thermal ignition to detonation. We have made considerable progress recently, resulting in the first broadly accurate model of this type for HMX. We have also recently provided the first theory of the phenomenon of melt acceleration in the thermal decomposition which indicates a universal mechanism applicable to this entire class of materials. The success of these models derives from the kinetic rate equations used, which are based upon rates activated by energies of vaporization and sublimation. The equations can be reduced to dimensionless form, yielding melt accelerated rates of thermal decomposition, ignition and detonation which are functions of two rate constants, one proportional to the liquid activity and another that can be interpreted as the simultaneous occupation of two defect states of the crystal. In this reduced form, data from a number of secondary explosives may be superposed on common curves. In this talk we explore the possibility that the underlying mechanism responsible for this behavior is linked to the equilibrium population of a crystal defect described by a vacancy in contact with local disorder.

  3. Rare-earth-doped photonic crystals for the development of solid-state optical cryocoolers (United States)

    Garcia-Adeva, Angel J.; Balda, Rolindes; Fernández, Joaquín


    Optical cryocoolers made of luminescent solids are very promising for many applications in the fields of optical telecommunications, aerospace industry, bioimaging, and phototherapy. To the present day, researchers have employed a number of crystal and glass host materials doped with rare-earth ions (Yb3+, Tm3+, and Er3+) to yield anti-Stokes optical refrigeration. In these host materials, the attainable minimum temperature is limited by the average phonon energy of the lattice and the impurity concentration. However, recently Ruan and Kaviany have theoretically demonstrated that the cooling efficiency can be dramatically enhanced when the host material doped with rare-earth ions is ground into a powder made of sub-micron size grains. This is due to two facts: firstly, the phonon spectrum is modified due to finite size of the grains and, secondly, light localization effects increase the photon density, leading to an enhanced absorptivity. In the present work, we propose that using a photonic crystal doped with rare earth ions offers many advantages with regards to getting a larger cooling efficiency at room temperature when compared to standard bulk materials or nano-powders. Indeed, apart to analogous phenomena to the ones predicted in nano-crystalline powders, there is the possibility of directly controlling the spontaneous emission rate of the ions embedded in the structure and, also, the absorption rate in the Stokes side of the absorption band by adequately tuning the density of photonic states, thus obtaining a large improvement in the cooling efficiency.

  4. High speed, high temperature electrical characterization of phase change materials: metastable phases, crystallization dynamics, and resistance drift. (United States)

    Dirisaglik, Faruk; Bakan, Gokhan; Jurado, Zoila; Muneer, Sadid; Akbulut, Mustafa; Rarey, Jonathan; Sullivan, Lindsay; Wennberg, Maren; King, Adrienne; Zhang, Lingyi; Nowak, Rebecca; Lam, Chung; Silva, Helena; Gokirmak, Ali


    During the fast switching in Ge2Sb2Te5 phase change memory devices, both the amorphous and fcc crystalline phases remain metastable beyond the fcc and hexagonal transition temperatures respectively. In this work, the metastable electrical properties together with crystallization times and resistance drift behaviour of GST are studied using a high-speed, device-level characterization technique in the temperature range of 300 K to 675 K.

  5. Expedient protocol for solid-phase synthesis of secondary and tertiary amines

    DEFF Research Database (Denmark)

    Olsen, Christian A; Witt, Matthias; Jaroszewski, Jerzy W


    [reaction: see text] An expedient solid-phase synthetic approach to secondary and tertiary amines was developed. The protocol employs conversion of resin-bound amino alcohols to the corresponding iodides, followed by iodide displacement with primary or secondary amines or with unprotected amino...... alcohols. This two-step procedure, affording products in good to excellent yields, is suitable for solid-phase synthesis of polyamines....

  6. A solid-phase approach to the phallotoxins: total synthesis of [Ala7]-phalloidin. (United States)

    Anderson, Marc O; Shelat, Anang A; Guy, R Kiplin


    Herein we report a solid-phase synthetic approach to [Ala7]-phalloidin (1). Prior syntheses of phallotoxins were carried out using solution-phase routes that required large scale and preclude library production. The route presented here consists of solution-phase preparation of key orthogonally protected amino acid building blocks, followed by a solid-phase peptide synthesis sequence, featuring two resin-bound macro-cyclization reactions. The final product mixture was composed of two atropisomeric compounds, one designated "natural" (1) and the other designated "non-natural" (1'). The structures of these species were modeled using restrained energy minimization with NMR-derived restraints.

  7. Morphogenesis of liquid crystal topological defects during the nematic-smectic A phase transition (United States)

    Gim, Min-Jun; Beller, Daniel A.; Yoon, Dong Ki


    The liquid crystalline phases of matter each possess distinct types of defects that have drawn great interest in areas such as topology, self-assembly and material micropatterning. However, relatively little is known about how defects in one liquid crystalline phase arise from defects or deformations in another phase upon crossing a phase transition. Here, we directly examine defects in the in situ thermal phase transition from nematic to smectic A in hybrid-aligned liquid crystal droplets on water substrates, using experimental, theoretical and numerical analyses. The hybrid-aligned nematic droplet spontaneously generates boojum defects. During cooling, toric focal conic domains arise through a sequence of morphological transformations involving nematic stripes and locally aligned focal conic domains. This simple experiment reveals a surprisingly complex pathway by which very different types of defects may be related across the nematic-smectic A phase transition, and presents new possibilities for controlled deformation and patterning of liquid crystals.

  8. Crystalline Dipeptide Nanobelts Based on Solid-Solid Phase Transformation Self-Assembly and Their Polarization Imaging of Cells. (United States)

    Song, Jingwen; Xing, Ruirui; Jiao, Tifeng; Peng, Qiuming; Yuan, Chengqian; Möhwald, Helmuth; Yan, Xuehai


    Controlled phase transformation involving biomolecular organization to generate dynamic biomimetic self-assembly systems and functional materials is currently an appealing topic of research on molecular materials. Herein, we achieve by ultrasonic irradiation the direct solid-solid transition of bioinspired dipeptide organization from triclinic structured aggregates to  nanofibers and eventually to monoclinic nanobelts with strong polarized luminescence. It is suggested that the locally high temperature and pressure produced by cavitation effects cleaves the hydrophobic, π-π stacking or self-locked intramolecular interactions involved in one phase state and then rearranges the molecular packing to form another well-ordered aromatic dipeptide crystalline structure. Such a sonication-modulated solid-solid phase transition evolution is governed by distinct molecular interactions at different stages of structural organization. The resulting crystalline nanobelts are for the first time applied for polarization imaging of cells, which can be advantageous to directly inspect the uptake and fate of nanoscale delivery platforms without labeling of fluorescent dyes. This finding provides a new perspective to comprehend the dynamic evolution of biomolecular self-organization with energy supply by an external field and open up a facile and versatile approach of using anisotropic nanostructures for polarization imaging of cells and even live organisms in future.

  9. Numerical analysis for a solid-core photonic crystal fiber with tunable zero dispersion wavelengths (United States)

    Barrientos-García, A.; Sukoivanov, Igor A.; Andrade-Lucio, J. A.; Guryev, Igor; Shulika, Oleksiy V.; Hernandez-García, J. C.; Ramos-Ortiz, G.


    Here we propose a simple design for a solid-core photonic crystal fiber made of silica by keeping the golden ratio (1.618) between pitch and air hole diameter Λ /d in a subset of six rings of air-holes with hexagonal arrangement. In the case when we have a pitch equal to one micron (Λ =1 μm), we need air-holes diameters d=0.618 μm in order to obtain the golden ratio parameter (Λ/d=1.618), and achieve two zero dispersion wavelength (ZDW) points at 725 nm and 1055 nm; this gives us the possibility to use this fiber in supercontinuum generation using a laser emission close to that points. We analyzed a series of fibers using this relation and show the possibilities of tunable ZDW in a wide range of wavelengths from 725 nm to 2000 nm with low losses and small effective area. In agreement with the ZDW point needed, the geometry of the structure can be modified to the point of having only three rings of air holes that surround the solid core with low losses and good confinement mode. The design proposed here is analyzed using the finite element method (FEM) with perfectly matched layers (PML), including the material dispersion directly into the model applying the Sellmeier's equation.

  10. Vapour phase synthesis of salol over solid acids via transesterification

    Indian Academy of Sciences (India)


    As the solubility of salicylic acid in phenol is very low, this method requires the use of the latter in higher molar ratios. Hence, the method of transesterification of methyl salicylate with phenol is employed wherein the reac- tants, being mutually soluble in one another, can be mixed in different molar ratios. Also, the solid acid.

  11. Insight into solid-liquid phase transfer catalyzed synthesis of ...

    Indian Academy of Sciences (India)

    Ganapati D Yadav


    Nov 16, 2017 ... C. Simple isolation process was employed to recover the product from the reaction mixture. A reaction mechanism was proposed and new kinetic model developed involving one liquid and two solid co-products. The activation energy for the reaction was calculated. This is the first example of its kind being ...

  12. Solid-Phase Synthesis of PEGylated Lipopeptides Using Click Chemistry

    DEFF Research Database (Denmark)

    Jølck, Rasmus Irming; Berg, Rolf Henrik; Andresen, Thomas Lars


    A versatile methodology for efficient synthesis of PEGylated lipopeptides via CuAAC “Click” conjugation between alkyne-bearing solid-supported lipopeptides and azido-functionalized PEGs is described. This new and very robust method offers a unique platform for synthesizing PEGylated lipopeptides ...

  13. Structural, vibrational and thermal characterization of phase transformation in L-histidinium bromide monohydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Moura, G.M. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Universidade Federal do Sul e Sudeste do Pará, ICEN, Marabá, PA 68505-080 (Brazil); Carvalho, J.O. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Instituto Federal do Tocantins, Araguaína, TO, 77.826-170 (Brazil); Silva, M.C.D.; Façanha Filho, P.F. [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil); Santos, A.O. dos, E-mail: [Universidade Federal do Maranhão, CCSST, Imperatriz, MA, 65900-410 (Brazil)


    L-Histidinium bromide monohydrate (LHBr) single crystal is a nonlinear optical material. In this work the high temperature phase transformation and the thermal stability of single crystals of LHBr was investigated by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry and Raman spectroscopy. The results showed the LHBr phase transformation of orthorhombic (P2{sub 1}2{sub 1}2{sub 1}) to monoclinic system (P 1 2 1) at 120 °C, with the lattice parameters a = 12.162(1) Å, b = 16.821(2) Å, c = 19.477(2) Å and β = 108.56(2)°. These techniques are complementary and confirm the structural phase transformation due to loss water of crystallization. - Highlights: • -histidinium bromide single crystal was grown by slow evaporation technique. • X-ray diffraction characterize the high-temperature phase transformation. • The structural phase transformation occur due to loss of water of crystallization. • The LHBr thermal expansion coefficients exhibit an anisotropic behavior.

  14. All-solid birefringent hybrid photonic crystal fiber based interferometric sensor for measurement of strain and temperature

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Scott Wu; Zhang, A. Ping


    A highly sensitive fiber-optic interferometric sensor based on an all-solid birefringent hybrid photonic crystal fiber (PCF) is demonstrated for measuring strain and temperature. A strain sensitivity of similar to 23.8 pm/mu epsilon and a thermal sensitivity of similar to-1.12 nm/degrees C...

  15. An analysis of the high-temperature phase structure of multiferroic solid solutions of the PFW–PT

    Directory of Open Access Journals (Sweden)

    Aleksandr A. Naberezhnov


    Full Text Available The temperature evolution of multiferroic solid solutions of the PFW–PT system, namely a (1–xPb(Fe2/3W1/3O3–(xPbTiO3 crystal structure where x = 0, 0.2, 0.3, has been studied by neutron powder diffraction in the region of the morphotropic phase boundary. The coexistence of cubic and tetragonal phases in the solutions with x = 0.2, 0.3 was found below T = 259 and 285K, respectively. As a result of the data treatment, the atom coordinates, the occupation factors and the temperature dependences of cell parameters were determined in the cubic perovskite phase. The refinement of the crystal structure in terms of ideal perovskite exhibited anomalously large Debye–Waller factors for the lead cations, indicating the appearance of random static displacements of these cations from the ideal perovskite (000 position. Using the split-ion model we estimated the value of Pb static shifts (∼0.1Å from their high-symmetry positions along the [110] direction. It was shown that these shifts decrease with increasing the PbTiO3 concentration.

  16. Solid state phase transition and vapor pressure studies in ammonium nitrate-potassium nitrate binary system (United States)

    Chien, Wen-Ming

    The solid-state phase transitions in ammonium nitrate (NH4NO 3) and potassium nitrate (KNO3) solid solutions and the equilibrium NH4NO3-KNO3 (AN-KN) phase diagram have been determined. The phase transitions and phase diagram were determined by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special "Dry Room" with very low humidity. In the X-ray diffraction experiments, the samples were heated on Pt-Rh strip and LaB6 or Si was added for internal calibration. Equilibrium phase diagram was also calculated by using the "FactSage" computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 25wt% KNO3 in NH4NO3 that is critical for air bag gas generators. The higher temperature KNO3 (KN I) phase has a wide stability range, from 100%KNO3 to 20%KNO3 solution. There is one eutectic, two eutectoids, and two peritectoids in this phase diagram. Two newly discovered solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria and lattice expansions during heating have been determined. Phase diagram calculations show a reasonable match of the phase boundaries. The total vapor pressures as well as the average molecular weights of pure ammonium nitrate and 16% KNO3 solid solution were measured at various temperatures by the torsion-Knudsen effusion method. The partial pressures of NH4NO3 (PNH4NO 3), NH3 (PNH3), and HNO3 (PHNO 3) have also been determined.

  17. Crystal Phase Quantum Well Emission with Digital Control

    DEFF Research Database (Denmark)

    Assali, S.; Laehnemann, J.; Vu, Thi Thu Trang


    One of the major challenges in the growth of quantum well and quantum dot heterostructures is the realization of atomically sharp interfaces. Nanowires provide a new opportunity to engineer the band structure as they facilitate the controlled switching of the crystal structure between the zinc...... of both types of charge carriers at the opposite interfaces of the WZ/ZB/WZ structure. This confinement leads to a novel type of transition across a ZB flat plate barrier. Here, we show digital tuning of the visible emission of WZ/ZB/WZ CPQWs in a GaP nanowire by changing the thickness of the ZB barrier...

  18. Mechanisms in Grain Growth Studied with the Phase Field Crystal Model (United States)

    McReynolds, Kevin Sullivan

    Grain growth is generally driven to minimize the overall interfacial energy in a system. However, the additional restraint that lattice planes be continuous across the grain boundary gives rise to a coupling between the normal motion of the grain boundary and the tangential motion of the lattice. The effects of coupling are studied in 2D using the phase field crystal model. Previous studies have shown that for an isolated circular grain with a low-angle boundary this coupling leads to rotation of the lattice as the grain shrinks. For high-angle grain boundaries the dislocations are limited in how close they can be without passing through one another. At higher temperatures, they are able to do so and the grain rotates and shrinks. At intermediate temperatures, this limitation causes the grain to shrink until it reaches a certain angle (and corresponding dislocation spacing) at which growth is arrested. In a system with a circular grain embedded at a planar symmetric tilt boundary, the coupling manifests as a rigid body translation of the grain's lattice as it shrinks. This translation is allowed by climb of dislocations in the boundary where lattice sites are removed at the leading edge of the grain and removed at the trailing edge. The dislocation reactions at the trijunctions provide the driving force for both translation and grain growth. Dislocations near the trijunction are attracted to the trijunction because the strain fields of the dislocations cancel each other. However, by pulling the boundary dislocation into the trijunction, the local dislocation spacing near the trijunction becomes larger than the equilibrium spacing. Since the grain is constrained and cannot rotate, this mismatch must be accommodated by strain. The relaxation of this strain drives translation and grain growth. At intermediate temperatures the larger elastic energy in the lattice will not allow this large dislocation spacing and corresponding misorientation mismatch and prevents the

  19. Poincaré-sphere representation of phase-mostly twisted nematic liquid crystal spatial light modulators


    Durán Bosch, Vicente Andrés; Clemente Pesudo, Pedro Javier; Martínez León, Lluís; Climent Jordà, Vicent; Lancis Sáez, Jesús


    We establish necessary conditions in order to design a phase-only wave front modulation system from a liquid crystal display. These conditions determine the dependence of the polarization state of the light emerging from the display on the addressing gray level. The analysis, which is carried out by means of the coherence-matrix formalism, includes the depolarization properties of the device. Two different types of polarization distributions at the output of the liquid crystal cel...

  20. Microscopic Mechanism of Doping-Induced Kinetically Constrained Crystallization in Phase-Change Materials. (United States)

    Lee, Tae Hoon; Loke, Desmond; Elliott, Stephen R


    A comprehensive microscopic mechanism of doping-induced kinetically constrained crystallization in phase-change materials is provided by investigating structural and dynamical dopant characteristics via ab initio molecular dynamics simulations. The information gained from this study may provide a basis for a fast screening of dopant species for electronic memory devices, or for understanding the general physics involved in the crystallization of doped glasses. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Mathematical and numerical modelling of fractional crystallization coupled with chemical exchanges and differential magma-solid transport in magma chambers (United States)

    Lakhssassi, Morad; Guy, Bernard; Cottin, Jean-Yves; Touboul, Eric


    The knowledge of the chemical evolution of magmas is a major concern in geochemistry and petrology. The jumps (or discontinuities) of chemical composition observed in volcanic series from the same province are also the subject of many studies. In particular the phenomenon of "Daly gap" (Daly 1910, 1925), the name given to the jump in chemical composition between the mafic rocks (basalt) and felsic rocks (trachyte, rhyolite, phonolite), corresponding to the absence or scarcity of rocks of intermediate composition (andesite), in both ocean and continental series. Some authors explain these compositional jumps thanks to the intervention of various geological phenomena which follow in time. For example, when a magma chamber turns from a closed to an open system, the lava of a specific composition is ejected to the surface, favoring the rise of the lightest, the most volatile-rich and the less sticky magmas to the surface of the earth (Geist et al., 1995, Thompson et al., 2001). The various explanations offered, although they agree satisfactorily with the natural data, most often lead us away from basic phenomena of melting / solidification, relative migration and chemical equilibrium between solid and liquid and involve various additional phenomena. In our study, we propose a numerical modelling of the crystallization of a closed magma chamber. The physical and mathematical model distinguishes three main classes of processes occurring simultaneously: - heat transfer and solidification, - relative migration between the solid and the liquid magma, - chemical reactions between the two (solid and liquid) phases. Writing the partial differential equations with dimensionless numbers makes two parameters appear, they express the respective ratios of the solidification velocity on the transport velocity, and the kinetics of chemical exchange on the transport velocity. The speed of relative movement between the solid and the liquid, the solidification velocity and the chemical

  2. Elastically mediated interactions between grain boundaries and precipitates in two-phase coherent solids (United States)

    Xu, Ye-Chuan; Geslin, Pierre-Antoine; Karma, Alain


    We investigate analytically and numerically the interaction between grain boundaries and second phase precipitates in two-phase coherent solids in the presence of misfit strain. Our numerical study uses amplitude equations that describe the interaction of composition and stress [R. Spatschek and A. Karma, Phys. Rev. B 81, 214201 (2010), 10.1103/PhysRevB.81.214201] and free-energies corresponding to two-dimensional hexagonal and three-dimensional BCC crystal structures that exhibit isotropic and anisotropic elastic properties, respectively. We consider two experimentally motivated geometries where (i) a lamellar precipitate nucleates along a planar grain boundary that is centered inside the precipitate, and (ii) a circular precipitate nucleates inside a grain at a finite distance to an initially planar grain boundary. For the first geometry, we find that the grain boundary becomes morphologically unstable due to the combination of long-range elastic interaction between the grain boundary and compositional domain boundaries, and shear-coupled grain boundary motion. We characterize this instability analytically by extending the linear stability analysis carried out recently [P.-A. Geslin, Y.-C. Xu, and A. Karma, Phys. Rev. Lett. 114, 105501 (2015), 10.1103/PhysRevLett.114.105501] to the more general case of elastic anisotropy. The analysis predicts that elastic anisotropy hinders but does not suppress the instability. Simulations also reveal that, in a well-developed nonlinear regime, this instability can lead to the break-up of low-angle grain boundaries when the misfit strain exceeds a threshold that depends on the grain boundary misorientation. For the second geometry, simulations show that the elastic interaction between an initially planar grain boundary and an adjacent circular precipitate causes the precipitate to migrate to and anchor at the grain boundary.

  3. Crystal structure, magnetism, {sup 89}Y solid state NMR, and {sup 121}Sb Moessbauer spectroscopic investigations of YIrSb

    Energy Technology Data Exchange (ETDEWEB)

    Benndorf, Christopher [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Heletta, Lukas; Block, Theresa; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institute of Physics in Sao Carlos, University of Sao Paulo, Sao Carlos (Brazil)


    The ternary antimonide YIrSb was synthesized from the binary precursor YIr and elemental antimony by a diffusion controlled solid-state reaction. Single crystals were obtained by a flux technique with elemental bismuth as an inert solvent. The YIrSb structure (TiNiSi type, space group Pnma) was refined from single-crystal X-ray diffractometer data: a = 711.06(9), b = 447.74(5), c = 784.20(8) pm, wR{sub 2} = 0.0455, 535 F{sup 2} values, 20 variables. {sup 89}Y solid state MAS NMR and {sup 121}Sb Moessbauer spectra show single resonance lines in agreement with single-crystal X-ray data. YIrSb is a Pauli paramagnet. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Interpretation of bent-crystal rocking curves using phase-space diagrams

    CERN Document Server

    Ren, B; Chapman, L D; Wu, X Y; Zhong, Z; Ivanov, I; Huang, X


    In developing a double bent-Laue crystal monochromator for synchrotron-based monochromatic computed tomography system, we applied a special projection of the phase-space diagram to interpret the shape of bent crystal rocking curves. Unlike the rigorous approach of the ray-tracing method, this graphical method provides direct pictures that allow checks of the physical significance of the shapes of the rocking curves, thereby providing quick guidelines for matching two bent crystals. The method's usefulness is demonstrated with our crexperimental results, and its limitations are discussed.

  5. Symmetry breaking in amorphous solids undergoing martensitic phase transformation - a relation to Landau's theory (United States)

    Fischlschweiger, Michael; Oberaigner, Eduard


    Martensitic phase transformation can be classified as displacive solid -solid phase transformations, where the symmetry of the high temperature phase (austenite) breaks when phase transformation occurs. The martensitic phase (low temperature phase) and its variants are products of symmetry breaking in solids. Based on a quasiparticle statistical mechanics approach the canonical free energy of a representative solid volume element consisting of several quasiparticles (representative mole number) can be derived. The symmetry breaking order parameter of the system is the total strain which is an ensemble mean value in the statistical mechanics concept. In the current theory the order parameter is a macroscopic strain in a sense that the representative volume element stands for the macroscopic level, whereas the lattice parameter changes are considered in the hamiltonian definition of each quasiparticle. Computational results of the developed theory correspond to experimentally observed phenomena in materials undergoing martensitic phase transformation. The present study is focusing the region nearby the phase transformation and shows how the developed theory for describing symmetry breaking and order parameter changes correspond to Landau's phenomenological theory of phase transitions.

  6. The contact angle of wetting of the solid phase of soil before and after chemical modification

    Directory of Open Access Journals (Sweden)

    Tyugai Zemfira


    Full Text Available Wettability of soil affects a wide variety of processes including infiltration, preferential flow and surface runoff. Wettability of surface is usually expressed in terms of contact angle (CA measurement. If the CA between liquid and solid surface is less than 90°, the surface is called hydrophilic, otherwise the surface is called hydrophobic. If the CA of water droplet on hydrophilic surface is in a range of 0-30° this surface is called superhydrophilic. In case of superhydrophobic surfaces the CA exceeds 150° that means that these surfaces are extremely difficult to wet. CA of wetting of mineral soil particles depends on the overlying organic and iron compounds. The object of study is a sample of the humus-accumulative horizon of typical chernozem (Kursk, Russia and two samples (horizons A1, B2 of red ferrallitic soils (Fr. Norfolk, NE Oceania. The soil samples were analyzed for organic carbon, forms of non-silicate iron and hydrophobic-hydrophilic composition of humic substances. CA of wetting was determined in the intact samples and after removal of organic matter (H2O2 treatment, amorphous and crystallized forms of iron. Static contact angles were determined with the sessile drop method using a digital goniometer (Drop Shape Analysis System, DSA100, Krüss GmbH, Hamburg, Germany. The contact angle was calculated by the Young–Laplace method (fitting of Young–Laplace equation to the drop shape. The measurements were repeated 10-15 times for every sample. Oxidation of organic matter (H2O2 treatment causes an increase in the values of CA of wetting (in chernozem from 9.3 to 28,0-29.5º, in ferrallitic soil from 18.0 − 27.3 to 22.4 − 33.4º. CA remained constant for chernozem and slightly decreased in the case of ferrallitic soil, when the removal of amorphous and crystallized forms of iron was performed on samples pretreated with H2O2. CA increase occurs after successive removal of nonsilicate forms of iron from soil samples of

  7. Phase transition of solid bismuth under high pressure (United States)

    Chen, Hai-Yan; Xiang, Shi-Kai; Yan, Xiao-Zhen; Zheng, Li-Rong; Zhang, Yi; Liu, Sheng-Gang; Bi, Yan


    As a widely used pressure calibrator, the structural phase transitions of bismuth from phase I, to phase II, to phase III, and then to phase V with increasing pressure at 300 K have been widely confirmed. However, there are different structural versions for phase III, most of which are determined by x-ray diffraction (XRD) technology. Using x-ray absorption fine structure (XAFS) measurements combined with ab initio calculations, we show that the proposed incommensurate composite structure of bismuth of the three configurations is the best option. An abnormal continuous increase of the nearest-neighbor distance of phase III with elevated pressure is also observed. The electronic structure transformation from semimetal to metal is responsible for the complex behavior of structure transformation. Project supported by the National Natural Science Foundation of China (Grant Nos. 10904133, 11304294, 11274281, 11404006, and U1230201), the Development Foundation of China Academy of Engineering Physics (Grant Nos. 2015B0101004, 2013B0401062, and 2012A0101001), the Research Foundation of the Laboratory of Shock Wave and Detonation, China (Grant No. 9140C670201140C67282).

  8. Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamaura, Kazunari, E-mail: [Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan)


    High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO{sub 3}, LiOsO{sub 3}, and Na{sub 2}OsO{sub 4}, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal–insulator transition in NaOsO{sub 3}, a ferroelectric-like transition in LiOsO{sub 3}, and high-temperature ferrimagnetism driven by a local structural distortion in Ca{sub 2}FeOsO{sub 6} may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices. - Graphical Abstract: Flux-grown crystals of NaOsO{sub 3} under high-pressure and high-temperature conditions in a belt-type apparatus. The crystal shows a magnetically driven metal–insulator transition at a temperature of 410 K. - Highlights: • Short review of high-pressure crystal growth of solid-state osmium oxides. • Wide variety of magnetic properties of solid-state osmium oxides. • Perovskite and related dense structures stabilized at 3–17 GPa.

  9. [Study on phase-matching of four-wave mixing spectrum in photonic crystal fiber]. (United States)

    Liu, Xiao-xu; Wang, Shu-tao; Zhao, Xing-tao; Chen, Shuang; Zhou, Gui-yao; Wu, Xi-jun; Li, Shu-guang; Hou, Lan-Tian


    In the present paper, the four-wave mixing principle of fiber was analyzed, and the high-gain phase-matching conditions were shown. The nonlinear coefficient and dispersion characteristics of photonic crystal fibers were calculated by multipole method. The phase mismatch characteristics of fibers with multiple zero-dispersion wavelengths were analyzed for the first time. The changing rules of phase matching wavelength with the pump wavelength and the pump power were obtained, and the phase matching curves were shown. The characteristics of phase matching wavelengths for different dispersion curves were analyzed. There are four new excitation wavelengths of four-wave mixing spectrum in two zero-dispersion wavelength photonic crystal fiers. Four-wave mixing spectroscopy of photonic crystal fibers with two zero-dispersion wavelengths was obtained in the experi-ent, which is consistent with the theoretical analysis, and verified the reliability of the phase matching theory. The fiber with multiple zero-dispersion wavelengths can create a ricbhphase-matching topology, excite more four-wave mixing wavelengths, ena-ling enhanced control over the spectral locations of the four-wave mixing and resonant-radiation bands emitted by solitons and short pulses. These provide theoretical guidance for photonic crystal fiber wavelength conversion and supercontinoum generation based on four-wave mixing.

  10. Crystal-Phase Quantum Wires: One-Dimensional Heterostructures with Atomically Flat Interfaces. (United States)

    Corfdir, Pierre; Li, Hong; Marquardt, Oliver; Gao, Guanhui; Molas, Maciej R; Zettler, Johannes K; van Treeck, David; Flissikowski, Timur; Potemski, Marek; Draxl, Claudia; Trampert, Achim; Fernández-Garrido, Sergio; Grahn, Holger T; Brandt, Oliver


    In semiconductor quantum-wire heterostructures, interface roughness leads to exciton localization and to a radiative decay rate much smaller than that expected for structures with flat interfaces. Here, we uncover the electronic and optical properties of the one-dimensional extended defects that form at the intersection between stacking faults and inversion domain boundaries in GaN nanowires. We show that they act as crystal-phase quantum wires, a novel one-dimensional quantum system with atomically flat interfaces. These quantum wires efficiently capture excitons whose radiative decay gives rise to an optical doublet at 3.36 eV at 4.2 K. The binding energy of excitons confined in crystal-phase quantum wires is measured to be more than twice larger than that of the bulk. As a result of their unprecedented interface quality, these crystal-phase quantum wires constitute a model system for the study of one-dimensional excitons.

  11. Dielectric properties and phase transition of zinc tris(thiourea) sulfate single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Moitra, S. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, West Bengal (India); Bhattacharya, S. [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, West Bengal (India); Kar, T. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, West Bengal (India); Ghosh, A. [Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, West Bengal (India)], E-mail:


    The dielectric properties and the ferroelectric to paraelectric phase transition of zinc tris(thiourea) sulfate (ZTS) single crystal have been investigated in a wide range of temperatures and frequencies. In the lower frequency region the real part of dielectric permittivity of the ZTS crystal shows a sudden increase at 323 K. Prominent first-order ferroelectric to paraelectric phase transition at 323 K has been observed in the plot of dielectric permittivity versus temperature at different frequencies. It has been observed that the phase transition occurs in ZTS crystal with a low degree of disorder. Surprisingly, it has been observed for ZTS that the value of the dielectric permittivity is only about 10 at high frequencies and is found to increase to 50 at low frequencies. Dielectric loss has higher values in the paraelectric region.

  12. Crystal Level Continuum Modeling of Phase Transformations: The (alpha) <--> (epsilon) Transformation in Iron

    Energy Technology Data Exchange (ETDEWEB)

    Barton, N R; Benson, D J; Becker, R; Bykov, Y; Caplan, M


    We present a crystal level model for thermo-mechanical deformation with phase transformation capabilities. The model is formulated to allow for large pressures (on the order of the elastic moduli) and makes use of a multiplicative decomposition of the deformation gradient. Elastic and thermal lattice distortions are combined into a single lattice stretch to allow the model to be used in conjunction with general equation of state relationships. Phase transformations change the mass fractions of the material constituents. The driving force for phase transformations includes terms arising from mechanical work, from the temperature dependent chemical free energy change on transformation, and from interaction energy among the constituents. Deformation results from both these phase transformations and elasto-viscoplastic deformation of the constituents themselves. Simulation results are given for the {alpha} to {epsilon} phase transformation in iron. Results include simulations of shock induced transformation in single crystals and of compression of polycrystals. Results are compared to available experimental data.

  13. Application of nuclear techniques in two-phase liquid-solid particles hydrotransport investigations

    Directory of Open Access Journals (Sweden)

    Zych Marcin


    Full Text Available The paper presents gamma radiation application to two-phase flow investigation in a vertical pipeline, where the flow of solid particles transported by water was examined by use of both: radiotracers and gamma-absorption method. The simultaneous use of two methods allows analyzing of important parameters of solid particles hydrotransport. In the described experiments as solid phase the ceramic models representing natural polymetallic ocean nodules were used. Radiotracers allow to track the movements of selected models, representing specified grain size and the designation of its velocity. However gamma-absorption method enables measurement of average solid-phase velocity. For analysis of electrical signals obtained from scintillation detectors the cross-correlation method has been applied.

  14. Tetragonal-cubic phase boundary in nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions synthesized by gel-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fabregas, Ismael O. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, Aldo F.; Fantini, Marcia C.A. [Instituto de Fisica, Universidade de Sao Paulo, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Millen, Ricardo P.; Temperini, Marcia L.A. [Instituto de Quimica, Universidade de Sao Paulo, Avenida Prof. Lineu Prestes 748, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Lamas, Diego G., E-mail: [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Laboratorio de Caracterizacion de Materiales, Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, (8300) Neuquen Capital, Prov. de Neuquen (Argentina)


    Research highlights: > Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders, that exhibit the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms (t' and t'') and the cubic phase. > Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. > The crystallographic features of ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. > Compositional t'/t'' and t''/cubic phase boundaries are located at (9 {+-} 1) and (10.5 {+-} 0.5) mol% Y{sub 2}O{sub 3}, respectively. > For the whole series of nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions, the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid

  15. An electro-optic experimental study of an unusual liquid crystal phase transition (United States)

    Staines, Daniel; Wicks, Derek; Havens, Austin; Fernsler, Jonathan


    Liquid crystal phases are highly sensitive to their surroundings and they interact with light in unusual ways: the index of refraction is different depending on the polarization of the incident light. This combination of properties makes them ideal for low-power liquid crystal displays (LCD's), ubiquitous in today's portable electronic devices. They are also beautiful: optical textures of liquid crystals show bright colors, with the color corresponding to the amount of retardation in the light polarized along different axes. These phases are fluid, but can nevertheless be highly ordered. We have developed a novel experimental analysis using a photometric calculation of microscopy images to perform a series of experiments on several liquid crystal materials, called ``de Vries'' smectics. Using this system, we examined how the structure of these phases changed under the influence of different boundary conditions, temperature, and applied electric fields. These unusual materials show the bizarre behavior of appearing to become less ordered with decreasing temperature. This phase, which is not fully understood, has advantageous optical properties that could lead to the next generation of liquid crystal displays.

  16. Determination of pesticide residues in Khat leaves by solid-phase ...

    African Journals Online (AJOL)

    Determination of pesticide residues in Khat leaves by solid-phase extraction and high-performance liquid chromatography. ... Isocratic and gradient analysis was carried out by means of high-performance liquid chromatography using different stationary phases to analyse methidathion, peconazole and dimethoate.

  17. Non-collinear wave mixing for a bulk wave phase velocity measurement in an isotropic solid

    NARCIS (Netherlands)

    Demcenko, A.


    A measurement method is presented to estimate the bulk wave phase velocity in an isotropic solid when longitudinal or shear wave velocity is known. This method is based on the non-collinear plane wave interaction theory and it does not need to estimate the phase time-of-flight and wave propagation

  18. Crystal structure of the commensurately modulated ζ phase of PAMC

    DEFF Research Database (Denmark)

    Harris, P.; Larsen, F.K.; Lebech, B.


    The commensurately modulated zeta low-temperature phase of bis(propylammonium) tetrachloromanganate(II), [NH3(C3H7)]2MnCl4, has been determined at 8 K. a = 7.437 (5), b = 7.082 (5), c = 13.096 (8) Angstrom, alpha = 105.59 (1)degrees. Superspace group P2(1)/b(0 beta 0)(1) over bar s, with beta = 1....../3, V = 664.4, Z = 2 D-x = 1.58 g cm(-3) Mo K alpha radiation, lambda = 0.71069 Angstrom, mu = 17.99 cm(-1) F(000) = 326, wR(F) = 0.064 for 1444 main reflections and wR(F) = 0.089 for 248 satellite reflections. The modulation vector flips and locks into a commensurate value compared with the epsilon...... phase, indicating a 'lock-in' and phase shift between adjacent modulated layers. The modulation waves do not change much from the values of the epsilon phase, which confirms the lock-in of the modulation vector; only some components of the modulations of the propylammonium chains appear...

  19. Pressure-induced phase transformations in L-alanine crystals

    DEFF Research Database (Denmark)

    Olsen, J. Staun; Gerward, Leif; Freire, P.T.C.


    Raman scattering and synchrotron X-ray diffraction have been used to investigate the high-pressure behavior of L-alanine. This study has confirmed a structural phase transition observed by Raman scattering at 2.3 GPa and identified it as a change from orthorhombic to tetragonal structure. Another...

  20. Ultrafast photoinduced structure phase transition in antimony single crystals

    NARCIS (Netherlands)

    Fausti, Daniele; Misochko, Oleg V.; van Loosdrecht, Paul H. M.


    Picosecond Raman scattering is used to study the photoinduced ultrafast dynamics in Peierls distorted antimony. We find evidence for an ultrafast nonthermal reversible structural phase transition. Most surprisingly, we find evidence that this transition evolves toward a lower symmetry in contrast to

  1. Simulation of bulk phases formed by polyphilic liquid crystal dendrimers

    Directory of Open Access Journals (Sweden)

    J.M. Ilnytskyi


    Full Text Available A coarse-grained simulation model for a third generation liquid crystalline dendrimer (LCDr is presented. It allows, for the first time, for a successful molecular simulation study of a relation between the shape of a polyphilic macromolecular mesogen and the symmetry of a macroscopic phase. The model dendrimer consists of a soft central sphere and 32 grafted chains each terminated by a mesogen group. The mesogenic pair interactions are modelled by the recently proposed soft core spherocylinder model of Lintuvuori and Wilson [J. Chem. Phys, 128, 044906, (2008]. Coarse-grained (CG molecular dynamics (MD simulations are performed on a melt of 100 molecules in the anisotropic-isobaric ensemble. The model LCDr shows conformational bistability, with both rod-like and disc-like conformations stable at lower temperatures. Each conformation can be induced by an external aligning field of appropriate symmetry that acts on the mesogens (uniaxial for rod-like and planar for disc-like, leading to formation of a monodomain smectic A (SmA or a columnar (Col phase, respectively. Both phases are stable for approximately the same temperature range and both exhibit a sharp transition to an isotropic cubic-like phase upon heating. We observe a very strong coupling between the conformation of the LCDr and the symmetry of a bulk phase, as suggested previously by theory. The study reveals rich potential in terms of the application of this form of CG modelling to the study of molecular self-assembly of liquid crystalline macromolecules.

  2. Solid-phase microextraction for bioconcentration studies according to OECD TG 305

    Energy Technology Data Exchange (ETDEWEB)

    Duering, Rolf-Alexander; Boehm, Leonard [Land Use and Nutrition (IFZ) Justus Liebig University Giessen, Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Giessen (Germany); Schlechtriem, Christian [Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Schmallenberg (Germany)


    An important aim of the European Community Regulation on chemicals and their safe use is the identification of (very) persistent, (very) bioaccumulative, and toxic substances. In other regulatory chemical safety assessments (pharmaceuticals, biocides, pesticides), the identification of such (very) persistent, (very) bioaccumulative, and toxic substances is of increasing importance. Solid-phase microextraction is especially capable of extracting total water concentrations as well as the freely dissolved fraction of analytes in the water phase, which is available for bioconcentration in fish. However, although already well established in environmental analyses to determine and quantify analytes mainly in aqueous matrices, solid-phase microextraction is still a rather unusual method in regulatory ecotoxicological research. Here, the potential benefits and drawbacks of solid-phase microextraction are discussed as an analytical routine approach for aquatic bioconcentration studies according to OECD TG 305, with a special focus on the testing of hydrophobic organic compounds characterized by log K{sub OW}> 5. (orig.)

  3. Morphology effect on the light scattering and dynamic response of polymer network liquid crystal phase modulator. (United States)

    Xiangjie, Zhao; Cangli, Liu; Jiazhu, Duan; Jiancheng, Zeng; Dayong, Zhang; Yongquan, Luo


    Polymer network liquid crystal (PNLC) was one of the most potential liquid crystal for submillisecond response phase modulation, which was possible to be applied in submillisecond response phase only spatial light modulator. But until now the light scattering when liquid crystal director was reoriented by external electric field limited its phase modulation application. Dynamic response of phase change when high voltage was applied was also not elucidated. The mechanism that determines the light scattering was studied by analyzing the polymer network morphology by SEM method. Samples were prepared by varying the polymerization temperature, UV curing intensity and polymerization time. The morphology effect on the dynamic response of phase change was studied, in which high voltage was usually applied and electro-striction effect was often induced. The experimental results indicate that the polymer network morphology was mainly characterized by cross linked single fibrils, cross linked fibril bundles or even both. Although the formation of fibril bundle usually induced large light scattering, such a polymer network could endure higher voltage. In contrast, although the formation of cross linked single fibrils induced small light scattering, such a polymer network cannot endure higher voltage. There is a tradeoff between the light scattering and high voltage endurance. The electro-optical properties such as threshold voltage and response time were taken to verify our conclusion. For future application, the monomer molecular structure, the liquid crystal solvent and the polymerization conditions should be optimized to generate optimal polymer network morphology.

  4. Rapidly Activated Dynamic Phase Transitions in Nonlinear Solids (United States)


    I Form Approv# edAD -A263 601 AiENTA11ON PAGE- f____________18 1. AGENCY USE ONLY (Lea"e blaWk 12. REPORT DATE 13. REPORT TYPE AND OATES COVEREO Feb...phase transforming media during high energy impact. Conversion of mechanical energy to thermal ener- gy has been studied by means of an extended theory...and Phase Structures in General Media , R. Fosdick, E. Dunn & M. Slemrod eds., IMA volume series, Springer- Verlag. Song, J. and T. L. Pence (1992

  5. Solid-Fluid Phase Equilibria for Natural Gas Processing at Low Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Longman


    Precipitation and deposition of solid components create potential risks of blocking gas passages in processes such as in LNG plants. To avoid such risks, experimental data and modelling of solid-fluid equilibrium should be used to optimize the design and operations. The objective of this work was to get a better understanding of the fundamentals of solid-fluid phase equilibrium. The specific focus of this work was to study solid-fluid phase behavior in systems of solid Co2, heavy hydrocarbons(HHC) and hydrate in equilibria with natural gas at low temperatures.Experimental methods for measuring solid-fluid equilibrium data in natural gas systems at low temperatures were extensively reviewed, and important and practical issues for designing experimental systems were summarized. The frost points in the Co2-methane systems (Co2 mole fraction 0.108 to 0.542) were measured in this work. Meanwhile, in another experimental setup, the water content in the gas phase was measured in the hydratemethane and hydrate-natural gas systems down to temperature 238.15 K. These data, together with data from other researchers, were used to verify the thermodynamic models. It is expensive and time-consuming to get experimental data at low temperatures, thus it is important to verify and use thermodynamic models to predict the solid-fluid phase behaviors. In the systems of solid Co2 and HHC in equilibrium with natural gas systems, the Soave-Redlich-Kwong (SRK) Equation of State (EOS) and simplified Perturbed-Chain Statistic Associating Fluid Theory (sPC-SAFT) EOS were used to calculate the fugacities in fluid phases. For solid phase, one fugacity model based on sublimation pressures and one model based on subcooled liquid were used. For correlating and predicting the hydrate behaviors, the Cubic-Plus-Association (CPA)EOS was used to model fluid phases and the hydrate-forming conditions were modelled by the solid solution theory of van der Waals and Platteeuw. Examples of applications of

  6. Polymeric Amorphous Solid Dispersions: A Review of Amorphization, Crystallization, Stabilization, Solid-State Characterization, and Aqueous Solubilization of Biopharmaceutical Classification System Class II Drugs. (United States)

    Baghel, Shrawan; Cathcart, Helen; O'Reilly, Niall J


    Poor water solubility of many drugs has emerged as one of the major challenges in the pharmaceutical world. Polymer-based amorphous solid dispersions have been considered as the major advancement in overcoming limited aqueous solubility and oral absorption issues. The principle drawback of this approach is that they can lack necessary stability and revert to the crystalline form on storage. Significant upfront development is, therefore, required to generate stable amorphous formulations. A thorough understanding of the processes occurring at a molecular level is imperative for the rational design of amorphous solid dispersion products. This review attempts to address the critical molecular and thermodynamic aspects governing the physicochemical properties of such systems. A brief introduction to Biopharmaceutical Classification System, solid dispersions, glass transition, and solubility advantage of amorphous drugs is provided. The objective of this review is to weigh the current understanding of solid dispersion chemistry and to critically review the theoretical, technical, and molecular aspects of solid dispersions (amorphization and crystallization) and potential advantage of polymers (stabilization and solubilization) as inert, hydrophilic, pharmaceutical carrier matrices. In addition, different preformulation tools for the rational selection of polymers, state-of-the-art techniques for preparation and characterization of polymeric amorphous solid dispersions, and drug supersaturation in gastric media are also discussed. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  7. Physical stability of l-ascorbic acid amorphous solid dispersions in different polymers: A study of polymer crystallization inhibitor properties. (United States)

    Christina, Belinda; Taylor, Lynne S; Mauer, Lisa J


    The effects of different polymer types on inhibiting the crystallization of ascorbic acid (VitC) from amorphous solid dispersions at various temperatures and relative humidities (RHs) were studied. Polymer properties (ability to form hydrogen bonds with VitC, hygroscopicity, and glass transition temperature (Tg)) were correlated to their crystallization inhibitor performance. Solid dispersions of VitC with different pectins, polyvinylpyrrolidone (PVP), and polyacrylic acid (PAA) were formed from lyophilized solutions. Crystallinity, VitC-polymer interactions, hygroscopicity, and Tg were determined using X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), moisture sorption isotherm, and differential scanning calorimetry (DSC) methods, respectively. XRPD amorphous VitC could not be formed by lyophilization in the absence of a polymer, nor in PAA dispersions, but could be formed in pectin and PVP dispersions. The VitC-pectin and PVP dispersions remained amorphous when stored at low RHs, but some crystallization occurred within one week at high RHs. Evidence of hydrogen bonding between VitC and both pectins and PVP, but not PAA, was found in FTIR spectra, and correlated better with physical stability than the Tg. The hygroscopicity of the polymer also influenced the stability of the amorphous VitC solid dispersions. A ranking of the polymer crystallization inhibitor properties was: PVP>pectin with lower degree of esterification (DE)>pectin with higher DE >PAA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Two-phase anaerobic digestion of vegetable market waste fraction of municipal solid waste and development of improved technology for phase separation in two-phase reactor. (United States)

    Majhi, Bijoy Kumar; Jash, Tushar


    Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-phase anaerobic digestion system should be preferred over the single-stage reactors. This is because VMW undergoes rapid acidification leading to accumulation of volatile fatty acids and consequent low pH resulting in frequent failure of digesters. The weakest part in the two-phase anaerobic reactors was the techniques applied for solid-liquid phase separation of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-phase reactor which consisted of a solid-phase reactor and a methane reactor was designed, built and operated with VMW fraction of Indian MSW. A robust type filter, which is unique in its implementation method, was developed and incorporated in the solid-phase reactor to separate the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-phase reactor with respect to biogas production, volatile solids reduction, pH and number of occurrence of clogging in the filtering system or choking in the process liquid transfer line. The system performed well and was operated successfully without the occurrence of clogging or any other disruptions throughout. Biogas production of 0.86-0.889m(3)kg(-1)VS, at OLR of 1.11-1.585kgm(-3)d(-1), were obtained from vegetable market waste, which were higher than the results reported for similar substrates digested in two-phase reactors. The VS reduction was 82-86%. The two-phase anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Comparison of the Molecular Dynamics of C70 in the Solid and Liquid Phases

    Directory of Open Access Journals (Sweden)

    R. M. Hughes


    Full Text Available A previous study of C70 in deuterated benzenes generated evidence suggesting C70 exhibited unique reorientational behavior depending on its environment. We present a comparison of the dynamic behavior of this fullerene, in the solid and solution phases, to explore any unique features between these two phases. The effective correlation times, τCeff, of C70 in the solid state are 2 to 3 times longer than in solution. In the solid state, a noticeable decrease in all the carbons' correlation times is seen between 293 K to 303 K; suggesting a transition from isotropic to anisotropic reorientational behavior at this temperature change. Although C70 in solution experiences van der Waals type interactions, these interactions are not strong enough to slow the solution-state motion below what is observed in the solid state. All observed differences in the diffusion constants, DX and DZ, in solution are smaller than in the solid state suggesting a lower energy of activation between these two modes of reorientation in the liquid phase. A small-step diffusion “like” condition appears to be thermally generated in the solid phase at 323 K.

  10. A molecular dynamics calculation of solid phase of malonic acid ...

    Indian Academy of Sciences (India)

    Sathya S R R Perumal

    We report an investigation into the triclinic phase of crystalline malonic acid. .... For the purpose of calculations of various properties, ... In general, there should be 34 or 81 components of second-rank tensor. Cijkl. Of these, only 36 are independent elastic constants. However, since the 6 × 6 matrix is symmetric, there are.

  11. A molecular dynamics calculation of solid phase of malonic acid ...

    Indian Academy of Sciences (India)

    Recent studies suggest that hydrogen bonds, in particular, hydrogen bond chains play an important role in determining the properties of a substance.We report an investigation into the triclinic phase of crystalline malonic acid. One of two intermolecular interaction potentials proposed here is seen to predict the lattice ...

  12. Solid phase extraction method for determination of mitragynine in ...

    African Journals Online (AJOL)

    phase high performance liquid chromatography (RP-HPLC) to determine mitragynine (MG) in rat and human urine, and to investigate the influence of caffeine (CF) on urinary excretion of MG in rats. Methods: A two-dimensional wash-elute ...

  13. Determination of 8 Synthetic Food Dyes by Solid Phase Extraction ...

    African Journals Online (AJOL)

    and thereafter determined by reverse phase high performance liquid chromatography (RP-HPLC) using a C18 column with .... Thermo Scientific Branstead Easypure II system. ... All the individual standard stock solutions (1000 mg L−1) were prepared in deionized water and kept in the dark place before use. The working ...

  14. New practical algorithm for modelling analyte recovery in bioanalytical reversed phase and mixed-mode solid phase extraction

    NARCIS (Netherlands)

    Hendriks, G.; Uges, D. R. A.; Franke, J. P.


    Solid phase extraction (SPE) is a widely used method for sample cleanup and sample concentration in bioanalytical sample preparation. A few methods to model the retention behaviour on SPE cartridges have been described previously but they are either not applicable to ionised species or are not

  15. Crystal structure and phase transitions in perovskite-like C(NH2)(3)SnCl3

    DEFF Research Database (Denmark)

    Szafranski, M.; Ståhl, Kenny


    X-ray single-crystal diffraction, high-temperature powder diffraction and differential thermal analysis at ambient and high pressure have been employed to study the crystal structure and phase transitions of guanidinium trichlorostannate, C(NH2)(3)SnCl3. At 295 K the crystal structure is orthorho...

  16. Phase-field-crystal study of grain boundary premelting and shearing in bcc iron (United States)

    Adland, Ari; Karma, Alain; Spatschek, Robert; Buta, Dorel; Asta, Mark


    We use the phase-field-crystal (PFC) method to investigate the equilibrium premelting and nonequilibrium shearing behaviors of [001] symmetric tilt grain boundaries (GBs) at high homologous temperature over the complete range of misorientation 0<θ<90∘ in classical models of bcc Fe. We characterize the dependence of the premelted layer width W as a function of temperature and misorientation. In addition, we compute the thermodynamic disjoining potential whose derivative with respect to W represents the structural force between crystal-melt interfaces due to the spatial overlap of density waves. The disjoining potential is also computed by molecular dynamics (MD) simulations, for quantitative comparison with PFC simulations, and coarse-grained amplitude equations (AE) derived from PFC that provide additional analytical insights. We find that, for GBs over an intermediate range of misorientation (θmin<θ<θmax), W diverges as the melting temperature is approached from below, corresponding to a purely repulsive disjoining potential, while for GBs outside this range (θ<θmin or θmax<θ<90∘) W remains finite at the melting point. In the latter case, W corresponds to a shallow attractive minimum of the disjoining potential. The misorientation range where W diverges predicted by PFC simulations is much smaller than the range predicted by MD simulations when the small dimensionless parameter ɛ of the PFC model is matched to liquid structure factor properties. However, it agrees well with MD simulations with a lower ɛ value chosen to match the ratio of bulk modulus and solid-liquid interfacial free energy, consistent with the amplitude-equation prediction that θmin and 90∘-θmax scale as ˜ɛ1/2. The incorporation of thermal fluctuations in PFC is found to have a negligible effect on this range. In response to a shear stress parallel to the GB plane, GBs in PFC simulations exhibit coupled motion normal to this plane or sliding. Furthermore, the coupling factor


    Energy Technology Data Exchange (ETDEWEB)

    Engstrom, T. A.; Yoder, N. C.; Crespi, V. H., E-mail:, E-mail:, E-mail: [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)


    A systematic search for multicomponent crystal structures is carried out for five different ternary systems of nuclei in a polarizable background of electrons, representative of accreted neutron star crusts and some white dwarfs. Candidate structures are “bred” by a genetic algorithm and optimized at constant pressure under the assumption of linear response (Thomas–Fermi) charge screening. Subsequent phase equilibria calculations reveal eight distinct crystal structures in the T = 0 bulk phase diagrams, five of which are complicated multinary structures not previously predicted in the context of compact object astrophysics. Frequent instances of geometrically similar but compositionally distinct phases give insight into structural preferences of systems with pairwise Yukawa interactions, including and extending to the regime of low-density colloidal suspensions made in a laboratory. As an application of these main results, we self-consistently couple the phase stability problem to the equations for a self-gravitating, hydrostatically stable white dwarf, with fixed overall composition. To our knowledge, this is the first attempt to incorporate complex multinary phases into the equilibrium phase-layering diagram and mass–radius-composition dependence, both of which are reported for He–C–O and C–O–Ne white dwarfs. Finite thickness interfacial phases (“interphases”) show up at the boundaries between single-component body-centered cubic (bcc) crystalline regions, some of which have lower lattice symmetry than cubic. A second application—quasi-static settling of heavy nuclei in white dwarfs—builds on our equilibrium phase-layering method. Tests of this nonequilibrium method reveal extra phases that play the role of transient host phases for the settling species.

  18. Role of the Strength of Drug-Polymer Interactions on the Molecular Mobility and Crystallization Inhibition in Ketoconazole Solid Dispersions. (United States)

    Mistry, Pinal; Mohapatra, Sarat; Gopinath, Tata; Vogt, Frederick G; Suryanarayanan, Raj


    The effects of specific drug-polymer interactions (ionic or hydrogen-bonding) on the molecular mobility of model amorphous solid dispersions (ASDs) were investigated. ASDs of ketoconazole (KTZ), a weakly basic drug, with each of poly(acrylic acid) (PAA), poly(2-hydroxyethyl methacrylate) (PHEMA), and polyvinylpyrrolidone (PVP) were prepared. Drug-polymer interactions in the ASDs were evaluated by infrared and solid-state NMR, the molecular mobility quantified by dielectric spectroscopy, and crystallization onset monitored by differential scanning calorimetry (DSC) and variable temperature X-ray diffractometry (VTXRD). KTZ likely exhibited ionic interactions with PAA, hydrogen-bonding with PHEMA, and weaker dipole-dipole interactions with PVP. On the basis of dielectric spectroscopy, the α-relaxation times of the ASDs followed the order: PAA > PHEMA > PVP. In addition, the presence of ionic interactions also translated to a dramatic and disproportionate decrease in mobility as a function of polymer concentration. On the basis of both DSC and VTXRD, an increase in strength of interaction translated to higher crystallization onset temperature and a decrease in extent of crystallization. Stronger drug-polymer interactions, by reducing the molecular mobility, can potentially delay the crystallization onset temperature as well as crystallization extent.

  19. Kinetics of the fcc → hcp Phase Transformation in Cu-Ge Solid Solutions Upon Isothermal Aging (United States)

    Polatidis, E.; Zotov, N.; Bischoff, E.; Mittemeijer, E. J.


    The kinetics of the ζ-phase formation from a supersaturated α-Cu(Ge) solid solution ( i.e., transformation from the fcc crystal structure to the hcp crystal structure) containing 10.8 at. pct Ge [at isothermal temperatures of 573 K, 613 K, and 653 K (300 °C, 340 °C, and 380 °C)] were studied by X-ray diffraction (XRD) for phase fraction determination. Both in situ and ex situ annealing experiments were performed. The transformation kinetics were modeled on the basis of a versatile modular model. The transformation kinetics complied with a site-saturation nucleation mode and strongly anisotropic interface-controlled growth mode in association with a corresponding impingement mode: diffusion of Ge (towards the stacking faults, SFs) does not control the transformation rate. Transmission electron microscopy (TEM) investigations showed that segregation of Ge at the stacking faults (SFs) takes place (relatively fast) prior to the structural transformation (fcc → hcp).

  20. Solute NMR study of a bimesogenic liquid crystal with two nematic phases (United States)

    Dong, R. Y.; Kohlmeier, A.; Tamba, M. G.; Mehl, G. H.; Burnell, E. E.


    Recent interest in bimesogenic liquid crystals showing two nematic phases has led us to investigate the nematic mean-field interactions in these nematic phases by using rigid solutes as probes. The nematic potential that is modelled by two independent Maier-Saupe terms is successful in fitting the observed dipolar couplings (molecular order parameters) of para-, meta- and ortho-dichlorobenzene solutes in both nematic phases of 39 wt.% 4-n-pentyl-4'-cyanobiphenyl (5CB) in α,ω-bis (4-4'-cyanobiphenyl) nonane (CBC9CB) to better than the 5% level. The derived liquid-crystal potential parameters G1 and G2 for each solute in the N and Nx phases are discussed.

  1. Zero phase delay in negative-refractive-index photonic crystal superlattices (United States)

    Kocaman, S.; Aras, M. S.; Hsieh, P.; McMillan, J. F.; Biris, C. G.; Panoiu, N. C.; Yu, M. B.; Kwong, D. L.; Stein, A.; Wong, C. W.


    We show that optical beams propagating in path-averaged zero-index photonic crystal superlattices can have zero phase delay. The nanofabricated superlattices consist of alternating stacks of negative index photonic crystals and positive index homogeneous dielectric media, where the phase differences corresponding to consecutive primary unit cells are measured with integrated Mach-Zehnder interferometers. These measurements demonstrate that at path-averaged zero-index frequencies the phase accumulation remains constant and equal to zero despite the increase in the physical path length. We further demonstrate experimentally that these superlattice zero- bandgaps remain invariant to geometrical changes of the photonic structure and have a center frequency which is deterministically tunable. The properties of the zero- gap frequencies, optical phase, and effective refractive indices are well described by detailed experimental measurements, rigorous theoretical analysis, and comprehensive numerical simulations.

  2. Zero Phase Delay in Negative-refractive-index Photonic Crystal Superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Stein, A.; Kocaman, S.; Aras, M.S.; Hsieh, P.-C. McMillan, J.F.; Biris, C.G.; Panoiu, N.C.; Yu, M.B.; Kwong, D.L.; Wong, C.W.


    We show that optical beams propagating in path-averaged zero-index photonic crystal superlattices can have zero phase delay. The nanofabricated superlattices consist of alternating stacks of negative index photonic crystals and positive index homogeneous dielectric media, where the phase differences corresponding to consecutive primary unit cells are measured with integrated Mach-Zehnder interferometers. These measurements demonstrate that at path-averaged zero-index frequencies the phase accumulation remains constant and equal to zero despite the increase in the physical path length. We further demonstrate experimentally that these superlattice zero- bandgaps remain invariant to geometrical changes of the photonic structure and have a center frequency which is deterministically tunable. The properties of the zero- gap frequencies, optical phase, and effective refractive indices are well described by detailed experimental measurements, rigorous theoretical analysis, and comprehensive numerical simulations.

  3. Bilayered smectic phase polymorphism in the dipolar Gay-Berne liquid crystal model. (United States)

    Houssa, Mohammed; Rull, Luis F; Romero-Enrique, Jose M


    We present computer simulations of the Gay-Berne model with a strong terminal dipole. We report the existence of different stable antiferroelectric interdigitated bilayered phases in this model with diverse in-plane organization. The occurrence of these phases depends crucially on the value of the molecular elongation kappa. For kappa=3 we find an interdigitated bilayered smectic-A phase (absent when there is no dipole) and a bilayered smectic-T (or crystal) with positional in-plane tetragonal ordering, different from the hexatic observed in the absence of the molecular dipole. For kappa=4, bilayered smectic-A and in-plane hexatic-ordered smectic-B (or crystal) phases are observed.

  4. Second-order phase transition at high-pressure in GeS crystal (United States)

    Hashimzade, F. M.; Huseinova, D. A.; Jahangirli, Z. A.; Mehdiyev, B. H.


    In this paper we give a theoretical proof of the existence of a second-order structural phase transition in the GeS at a pressure of 35.4 GPa. We use the plane-wave pseudopotential approach to the density functional theory in the local density approximation. The evidence of the phase transition is the abrupt change in the bulk modulus as the volume of the unit cell of the crystal changes continuously. We show that the phase transition is caused by the softening of the low-frequency fully symmetric interlayer mode with increasing pressure. As a result, phase transition of a displacement type takes place with the change of translational symmetry of the crystal from the simple orthorhombic to the base-centered orthorhombic (Pbnm(D2h16)→Cmcm(D2h17)).

  5. Nucleation of domain walls in iron garnet single crystals grown from liquid phase epitaxy (United States)

    Shirai, Kazushi; Ishikura, Kenji; Takeda, Norio


    When bismuth-substituted iron garnet (RBi)IG single crystals grown from liquid-phase-epitaxy (LPE) are magnetized, the magnetic domain structure gradually evolves. However the domain-wall nucleation that occurs during the demagnetization is not yet understood clearly. This phenomenon is important, because the working of some optical devices that utilize (RBi)IG single crystals depends directly on the formation of domains of opposite direction. In this paper, the authors present a theoretical description of domain-wall nucleation in LPE-grown (RBi)IG single crystals. It was found that the nucleation field is determined by the strength of the microscopic domain-wall which is fixed on the surface of the crystal. Furthermore, the nucleation field is modified by the addition of a magnetic field.

  6. Hydrophobically assisted switching phase synthesis: the flexible combination of solid-phase and solution-phase reactions employed for oligosaccharide preparation. (United States)

    Bauer, Jörg; Rademann, Jörg


    Hydrophobically assisted switching phase (HASP) synthesis is a concept that allows the choice between the advantages of solid-supported chemistry and those of solution-phase synthesis. Starting from the examination of adsorption and desorption properties of hydrophobic molecules to and from reversed-phase silica, we designed a dilipid as a quantitative and fully reversible HASP anchor, permitting final product release. The utility of this new tool in synthetic organic chemistry was demonstrated on oligosaccharide preparation. The synthesis of a pentarhamnoside was accomplished by repetitive glycosylation reactions. Glycosylations were conducted preferably in solution, whereas all protecting group manipulations were performed on solid support. Without the need for chromatographic purification of intermediates, the HASP system furnished the final product after 12 linear steps with average yields of 94% per step at a scale of 0.1 mmol, thus overcoming several of the limitations encountered in the solid-phase synthesis of complex carbohydrates.

  7. A High-Throughput Process for the Solid-Phase Purification of Synthetic DNA Sequences. (United States)

    Grajkowski, Andrzej; Cieślak, Jacek; Beaucage, Serge L


    An efficient process for the purification of synthetic phosphorothioate and native DNA sequences is presented. The process is based on the use of an aminopropylated silica gel support functionalized with aminooxyalkyl functions to enable capture of DNA sequences through an oximation reaction with the keto function of a linker conjugated to the 5'-terminus of DNA sequences. Deoxyribonucleoside phosphoramidites carrying this linker, as a 5'-hydroxyl protecting group, have been synthesized for incorporation into DNA sequences during the last coupling step of a standard solid-phase synthesis protocol executed on a controlled pore glass (CPG) support. Solid-phase capture of the nucleobase- and phosphate-deprotected DNA sequences released from the CPG support is demonstrated to proceed near quantitatively. Shorter than full-length DNA sequences are first washed away from the capture support; the solid-phase purified DNA sequences are then released from this support upon reaction with tetra-n-butylammonium fluoride in dry dimethylsulfoxide (DMSO) and precipitated in tetrahydrofuran (THF). The purity of solid-phase-purified DNA sequences exceeds 98%. The simulated high-throughput and scalability features of the solid-phase purification process are demonstrated without sacrificing purity of the DNA sequences. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  8. Determination of melamine in aquaculture feed samples based on molecularly imprinted solid-phase extraction. (United States)

    Lian, Ziru; Liang, Zhenlin; Wang, Jiangtao


    This research highlights the application of highly efficient molecularly imprinted solid-phase extraction for the preconcentration and analysis of melamine in aquaculture feed samples. Melamine-imprinted polymers were synthesized employing methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker, respectively. The characteristics of obtained polymers were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy and binding experiments. The imprinted polymers showed an excellent adsorption ability for melamine and were applied as special solid-phase extraction sorbents for the selective cleanup of melamine. An off-line molecularly imprinted solid-phase extraction procedure was developed for the separation and enrichment of melamine from aquaculture feed samples prior to high-performance liquid chromatography analysis. Optimum molecularly imprinted solid-phase extraction conditions led to recoveries of the target in spiked feed samples in the range 84.6-96.6% and the relative standard deviation less than 3.38% (n = 3). The aquaculture feed sample was determined, and there was no melamine found. The results showed that the molecularly imprinted solid-phase extraction protocols permitted the sensitive, uncomplicated and inexpensive separation and pre-treatment of melamine in aquaculture feed samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Non-equilibrium phase transitions in a liquid crystal. (United States)

    Dan, K; Roy, M; Datta, A


    The present manuscript describes kinetic behaviour of the glass transition and non-equilibrium features of the "Nematic-Isotropic" (N-I) phase transition of a well known liquid crystalline material N-(4-methoxybenzylidene)-4-butylaniline from the effects of heating rate and initial temperature on the transitions, through differential scanning calorimetry (DSC), Fourier transform infrared and fluorescence spectroscopy. Around the vicinity of the glass transition temperature (Tg), while only a change in the baseline of the ΔCp vs T curve is observed for heating rate (β) > 5 K min(-1), consistent with a glass transition, a clear peak for β ≤ 5 K min(-1) and the rapid reduction in the ΔCp value from the former to the latter rate correspond to an order-disorder transition and a transition from ergodic to non-ergodic behaviour. The ln β vs 1000/T curve for the glass transition shows convex Arrhenius behaviour that can be explained very well by a purely entropic activation barrier [Dan et al., Eur. Phys. Lett. 108, 36007 (2014)]. Fourier transform infrared spectroscopy indicates sudden freezing of the out-of-plane distortion vibrations of the benzene rings around the glass transition temperature and a considerable red shift indicating enhanced coplanarity of the benzene rings and, consequently, enhancement in the molecular ordering compared to room temperature. We further provide a direct experimental evidence of the non-equilibrium nature of the N-I transition through the dependence of this transition temperature (TNI) and associated enthalpy change (ΔH) on the initial temperature (at fixed β-values) for the DSC scans. A plausible qualitative explanation based on Mesquita's extension of Landau-deGennes theory [O. N. de Mesquita, Braz. J. Phys. 28, 257 (1998)] has been put forward. The change in the molecular ordering from nematic to isotropic phase has been investigated through fluorescence anisotropy measurements where the order parameter, quantified by the

  10. Growth of Cd0.96Zn0.04Te single crystals by vapor phase gas transport method

    Directory of Open Access Journals (Sweden)

    S. H. Tabatabai Yazdi


    Full Text Available   Cd0.96Zn0.04Te crystals were grown using vapor phase gas transport method (VPGT. The results show that dendritic crystals with grain size up to 3.5 mm can be grown with this technique. X-ray diffraction and Laue back-reflection patterns show that dendritic crystals are single-phase, whose single crystal grains are randomly oriented with respect to the gas-transport axis. Electrical measurements, carried out using Van der Pauw method, show that the as-grown crystals have resistivity of about 104 Ω cm and n-type conductivity.

  11. Electrically controlled phases of partially polarized light and orientational Kerr effect in liquid crystal ferroelectrics

    Directory of Open Access Journals (Sweden)

    Kiselev Alexei D.


    Full Text Available We study the electro-optic properties of subwavelength-pitch deformed-helix ferroelectric liquid crystals illuminated with partially polarized light. In an experimental setup based on the Mach-Zehnder interferometer, it is found that the interference pattern crucially depends on the degree of polarization of the incident light. We evaluate the electric field dependence of both the Pancharatnam relative phase and the geometric phase for the general case of nonunitarily evolving mixed polarization states.

  12. Kinetics of the direct sulfation of limestone at the initial stage of crystal growth of the solid product

    DEFF Research Database (Denmark)

    Hu, Guilin; Dam-Johansen, Kim; Wedel, Stig


    The direct sulfation of limestone was studied in a quartz bench scale fixed‐bed reactor with the technique of data deconvolution. The obtained results show that the direct sulfation of limestone has a two‐period kinetic behavior: a short initial sulfation period with high but fast decreasing...... such as SO2, O2, and CO2 and the temperature. The sulfation process in the initial stage of the period with product crystal growth can be described by the combination of the sulfation reaction at the gas–solid interface, diffusion of the product ions toward the product crystal grains, diffusion of carbonate...

  13. The synthesis and properties of the phases obtained by solid-solid reactions


    Blonska-Tabero A.; Bosacka M.; Dabrowska G.; Filipek E.; Piz M.; Rychlowska-Himmel I.; Tabero P.; Tomaszewicz E.


    The presented work encompasses the subject of the studies and the results obtained over the last years by the research workers of the Department of Inorganic Chemistry. They include mainly the studies on the reactivity of metal oxides, searching for new phases in binary and ternary systems of metal oxides as well as describing phase relations establishing in such systems. They also encompass works on the extensive characteristics of physico-chemical properties of the newly obtained compounds.

  14. The synthesis and properties of the phases obtained by solid-solid reactions

    Directory of Open Access Journals (Sweden)

    Blonska-Tabero A.


    Full Text Available The presented work encompasses the subject of the studies and the results obtained over the last years by the research workers of the Department of Inorganic Chemistry. They include mainly the studies on the reactivity of metal oxides, searching for new phases in binary and ternary systems of metal oxides as well as describing phase relations establishing in such systems. They also encompass works on the extensive characteristics of physico-chemical properties of the newly obtained compounds.

  15. Direct measurement of the propagation of the phase-transition region of liquid crystals (United States)

    Sato, Takahiro; Katayama, Kenji


    Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions. Despite the technological and fundamental importance of these long-range changes, there is no good physical property with which to express them for the liquid crystal. Here, we show direct measurements of the propagation of structural or orientational changes due to long-range molecular interactions in liquid crystals. We induced a patterned phase transition in a liquid crystal via illumination with a fringe pattern and observed the propagation of the phase-transition region. We determined that the propagation occurred in a ballistic manner with a velocity of 80-110 m/s and that two types of propagation—side-by-side and head-to-tail molecular interactions—were found.

  16. Femtosecond laser-induced ultrafast transient snapshots and crystallization dynamics in phase change material. (United States)

    Sahu, Smriti; Sharma, Rituraj; Adarsh, K V; Manivannan, Anbarasu


    We report here femtosecond laser-driven transient snapshots of ultrafast crystallization of Ge2Sb2Te5 films from its as-deposited amorphous phase, and the local structural change is validated by micro-Raman spectroscopy and x-ray diffraction. The decay time constant of ∼5  ps in transient spectra with a precise temporal resolution using 400 nm (pump) reveals about 68 volumetric percentage crystallization at a remarkably low fluence of 4.78  mJ·cm-2. This is attributed to reiterated excitation after a complete carrier relaxation and formation of a long-lasting transient phase at sub-threshold fluences. Furthermore, Raman spectra of irradiated spots confirm defective-octahedral modes at 110 and 160  cm-1 validating crystallization.

  17. Highly non-linear solid core photonic crystal fiber with one nano hole

    Energy Technology Data Exchange (ETDEWEB)

    Gangwar, Rahul Kumar, E-mail:; Bhardwaj, Vanita, E-mail:; Singh, Vinod Kumar, E-mail: [Department of Applied Physics, Indian School of Mines, Dhanbad, Jharkhand (India)


    The numerical study of newly designed solid core photonic crystal fiber (SCPCF) having three hexagonal air hole rings in cladding region and one small nano hole at the center are presented. By using full vectorial finite element method (FV-FEM), we analyses the optical properties like effective area, nonlinearity and confinement loss of the proposed PCF. Results show that the change in core diameter controls the effective area, nonlinearity and confinement loss. A low effective area (3.34 µm{sup 2}), high nonlinearity (36.34 W{sup −1}km{sup −1}) and low confinement loss (0.00106 dB/km) are achieved at the communication wavelength 1.55 µm for the SCPCF having core air hole diameter 0.10 µm, cladding air holes diameter 1.00 µm and pitch 2.50 µm. This type of PCF is very useful in non-linear applications such as supercontinuum generation, four wave mixing, second harmonic generation etc.

  18. Phase behavior of chromonic liquid crystal mixtures of Sunset Yellow and Disodium Cromoglycate (United States)

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


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

  19. Systematic Procedure for Generating Operational Policies to Achieve Target Crystal Size Distribution (CSD) in Batch Cooling Crystallization

    DEFF Research Database (Denmark)

    Abdul Samad, Noor Asma Fazli; Singh, Ravendra; Sin, Gürkan

    Batch cooling crystallization is one of the important unit operations involving separation of solid-liquid phases. Usually the most common crystal product qualities are directly related to the crystal size distribution (CSD). However the main difficulty in batch crystallization is to obtain a uni...

  20. Studies of Phase Transformation in Molecular Crystals Using the Positron Annihilation Technique

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard; Lightbody, David; Sherwood, John N.


    An examination has been made of the brittle/plastic phase transformation in the molecular crystals cyclohexane, DL-camphene and succinonitrile using the positron annihilation technique. In each material, the transition is characterized by a distinct increase in ortho-positronium lifetime. The inf...

  1. On the mechanical stability of the body-centered cubic phase and the emergence of a metastable cI16 phase in classical hard sphere solids. (United States)

    Warshavsky, Vadim B; Ford, David M; Monson, Peter A


    The stability of the body-centered cubic (bcc) solid phase of classical hard spheres is of intrinsic interest and is also relevant to the development of perturbation theories for bcc solids of other model systems. Using canonical ensemble Monte Carlo, we simulated systems initialized in a perfect bcc lattice at various densities in the solid region. We observed that the systems rapidly evolved into one of four structures that then persisted for the duration of the simulation. Remarkably, one of these structures was identified as cI16, a cubic crystalline structure with 16 particles in the unit cell, which has recently been observed experimentally in lithium and sodium solids at high pressures. The other three structures do not exhibit crystalline order but are characterized by common patterns in the radial distribution function and bond-orientational order parameter distribution; we refer to them as bcc-di, with i ranging from 1 to 3. We found similar outcomes when employing any of the three single occupancy cell (SOC) restrictions commonly used in the literature. We also ran long constant-pressure simulations with box shape fluctuations initiated from bcc and cI16 initial configurations. At lower pressures, all the systems evolved to defective face-centered cubic (fcc) or hexagonal close-packed (hcp) structures. At higher pressures, most of the systems initiated as bcc evolved to cI16 with some evolving to defective fcc/hcp. High pressure systems initiated from cI16 remained in that structure. We computed the chemical potential of cI16 using the Einstein crystal reference method and found that it is higher than that of fcc by ∼0.5kT-2.5kT over the pressure range studied, with the difference increasing with pressure. We find that the undistorted bcc solid, even with constant-volume and SOC restrictions applied, is so mechanically unstable that it is unsuitable for consideration as a metastable phase or as a reference system for studying bcc phases of other

  2. On the mechanical stability of the body-centered cubic phase and the emergence of a metastable cI16 phase in classical hard sphere solids (United States)

    Warshavsky, Vadim B.; Ford, David M.; Monson, Peter A.


    The stability of the body-centered cubic (bcc) solid phase of classical hard spheres is of intrinsic interest and is also relevant to the development of perturbation theories for bcc solids of other model systems. Using canonical ensemble Monte Carlo, we simulated systems initialized in a perfect bcc lattice at various densities in the solid region. We observed that the systems rapidly evolved into one of four structures that then persisted for the duration of the simulation. Remarkably, one of these structures was identified as cI16, a cubic crystalline structure with 16 particles in the unit cell, which has recently been observed experimentally in lithium and sodium solids at high pressures. The other three structures do not exhibit crystalline order but are characterized by common patterns in the radial distribution function and bond-orientational order parameter distribution; we refer to them as bcc-di, with i ranging from 1 to 3. We found similar outcomes when employing any of the three single occupancy cell (SOC) restrictions commonly used in the literature. We also ran long constant-pressure simulations with box shape fluctuations initiated from bcc and cI16 initial configurations. At lower pressures, all the systems evolved to defective face-centered cubic (fcc) or hexagonal close-packed (hcp) structures. At higher pressures, most of the systems initiated as bcc evolved to cI16 with some evolving to defective fcc/hcp. High pressure systems initiated from cI16 remained in that structure. We computed the chemical potential of cI16 using the Einstein crystal reference method and found that it is higher than that of fcc by ˜0.5kT-2.5kT over the pressure range studied, with the difference increasing with pressure. We find that the undistorted bcc solid, even with constant-volume and SOC restrictions applied, is so mechanically unstable that it is unsuitable for consideration as a metastable phase or as a reference system for studying bcc phases of other systems

  3. Dielectric properties and molecular motions of liquid crystal molecules in 4-(2-methylbytylphenyl 4-(4-octylphenylbenzoate liquid crystal having blue phase (CE8

    Directory of Open Access Journals (Sweden)

    Otowski W.


    Full Text Available Blue phase liquid crystals exhibit unique properties which are used in the new type of display. A blue-phase liquid crystal display was first presented commercially by Samsung in 2007. The blue-phase-three-color pixel display eliminates the need for color filters. This type of display uses blue-phase multi-component liquid crystal. Considering the one-component systems, it turns out that they are stable only in a very narrow range of temperatures between the isotropic and the chiral nematic phase (about 1 K. In 2005, a wide temperature range BP multi-component system was reported by researchers from the University of Cambridge. There are still several unsolved problems left. One of them is chemical stability and reliability. Therefore, the knowledge of molecular dynamics of blue phase liquid crystal is a prerequisite for understanding of blue-phase multi-component system. Understanding the molecular dynamics of a single component liquid-crystalline blue phase system can facilitate the solution of these problems. We present the molecular dynamics investigation of 4-(2-methylbytylphenyl 4-(4-octylphenylbenzoate (CE8, which may be a good candidate to form materials suitable for blue-phase liquid crystal displays.

  4. Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination (United States)

    Mogolodi Dimpe, K.; Mpupa, Anele; Nomngongo, Philiswa N.


    This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L- 1 and 1.7 μg L- 1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were > 6%.The maximum adsorption capacity was 138 mg g- 1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

  5. Induced Smectic X Phase Through Intermolecular Hydrogen-Bonded Liquid Crystals Formed Between Citric Acid and p- n-(Octyloxy)Benzoic Acid (United States)

    Sundaram, S.; Subhasri, P.; Rajasekaran, T. R.; Jayaprakasam, R.; Senthil, T. S.; Vijayakumar, V. N.


    Hydrogen-bonded liquid crystal (HBLC) is synthesized from citric acid (CA) and 4-(octyloxy)benzoic acid (8OBA) with different mole ratios. Fourier transform infrared spectroscopy (FT-IR) confirms the presence of hydrogen bond between CA and 8OBA. Nuclear magnetic resonance (NMR) spectroscopic studies validate the intermolecular complementary, cyclic type of hydrogen bond, and molecular environment in the designed HBLC complex. Powder X-ray diffraction analysis reveals the monoclinic nature of liquid crystal complex in solid phase. Liquid crystal parameters such as phase transition temperature and enthalpy values for the corresponding mesogenic phases are investigated using a polarizing optical microscope (POM) and differential scanning calorimetry (DSC). It is observed that the change in chain length and steric hindrance while increasing the mole ratio in HBLC complex induces a new smectic X (Sm X) along with higher-order smectic G (Sm G) phases by quenching of smectic C (Sm C). From the experimental observations, induced Sm X phase has been identified as a finger print texture. Also, Sm G is a multi-colored mosaic texture in 1:1, 1:2, and 1:3 mol ratios. The optical tilt angle, thermal stability factor, and enhanced thermal span width of CA + 8OBA complex are discussed.

  6. Biological nitrate removal from water and wastewater by solid-phase denitrification process. (United States)

    Wang, Jianlong; Chu, Libing


    Nitrate pollution in receiving waters has become a serious issue worldwide. Solid-phase denitrification process is an emerging technology, which has received increasing attention in recent years. It uses biodegradable polymers as both the carbon source and biofilm carrier for denitrifying microorganisms. A vast array of natural and synthetic biopolymers, including woodchips, sawdust, straw, cotton, maize cobs, seaweed, bark, polyhydroxyalkanoate (PHA), polycaprolactone (PCL), polybutylene succinate (PBS) and polylactic acid (PLA), have been widely used for denitrification due to their good performance, low cost and large available quantities. This paper presents an overview on the application of solid-phase denitrification in nitrate removal from drinking water, groundwater, aquaculture wastewater, the secondary effluent and wastewater with low C/N ratio. The types of solid carbon source, the influencing factors, the microbial community of biofilm attached on the biodegradable carriers, the potential adverse effect, and the cost of denitrification process are introduced and evaluated. Woodchips and polycaprolactone are the popular and competitive natural plant-like and synthetic biodegradable polymers used for denitrification, respectively. Most of the denitrifiers reported in solid-phase denitrification affiliated to the family Comamonadaceae in the class Betaproteobacteria. The members of genera Diaphorobacter, Acidovorax and Simplicispira were mostly reported. In future study, more attention should be paid to the simultaneous removal of nitrate and toxic organic contaminants such as pesticide and PPCPs by solid-phase denitrification, to the elucidation of the metabolic and regulatory relationship between decomposition of solid carbon source and denitrification, and to the post-treatment of the municipal secondary effluent. Solid-phase denitrification process is a promising technology for the removal of nitrate from water and wastewater. Copyright © 2016

  7. A scheme for a single molecule phase-shift gate in a solid matrix. (United States)

    Cui, Xiao-Dong; Zheng, Yujun


    We propose a feasible scheme to implement a phase-shift gate ((1 0) (0 eiγ)) based on a two-state single molecule in a solid matrix, where γ is a geometric phase controlled through a fast on-resonant laser field and a slow off-resonant radio-frequency field. In our scheme, a non-Hermitian quantum model is employed to characterize the single molecule in a solid matrix including the spontaneous decay effect. By the coupling between the radio-frequency field and the two-state permanent dipole difference resulting from the solid matrix, the spontaneous decay fatal to the preservation of geometric phase can be effectively suppressed for a considerably long waiting time.

  8. Solid-phase assays for the detection of alloantibody against human leukocyte antigens: panacea or Pandora? (United States)

    Roberts, T; Tumer, G; Gebel, H M; Bray, R A


    Serological assessments of antibodies directed against human leucocyte antigens (HLA) formed the basis of early histocompatibility testing (Patel & Terasaki, 1969 N Engl J Med, 280, 735). However, over the past decade, significant advances in HLA antibody detection technologies have emerged. The development and implementation of solid-phase assays has led to safer and more efficient allocation of organs by effectively distinguishing HLA from non-HLA antibodies. Although solid-phase assays are not standardized, they are widely accepted as the new 'gold standard'. However, this technology is not without its challenges. This review is intended to provide a better understanding of solid-phase HLA antibody testing and will focus on important caveats associated with this evolving technology. Examples of the limitations of the technology as well as common data misinterpretations will be shown. Both of which could pose potential harm to transplant recipients (Tait et al., Transplantation, 95, 19). © 2014 John Wiley & Sons Ltd.

  9. Solid-Phase Synthesis of Amine/Carboxyl Substituted Prolines and Proline Homologues: Scope and Limitations. (United States)

    Zhou, Ziniu; Scott, William L; O'Donnell, Martin J


    A solid-phase procedure is used to synthesize racemic peptidomimetics based on the fundamental peptide unit. The peptidomimetics are constructed around proline or proline homologues variably substituted at the amine and carbonyl sites. The procedure expands the diversity of substituted peptidomimetic molecules available to the Distributed Drug Discovery (D3) project. Using a BAL-based solid-phase synthetic sequence the proline or proline homologue subunit is both constructed and incorporated into the peptidomimetic by an α-alkylation, hydrolysis and intramolecular cyclization sequence. Further transformations on solid-phase provide access to a variety of piperazine derivatives representing a class of molecules known to exhibit central nervous system activity. The procedure works well with proline cores, but with larger six- and seven-membered ring homologues the nature of the carboxylic acid acylating the cyclic amine can lead to side reactions and result in poor overall yields.

  10. Numerical simulation and analysis of solid-liquid two-phase flow in centrifugal pump (United States)

    Zhang, Yuliang; Li, Yi; Cui, Baoling; Zhu, Zuchao; Dou, Huashu


    The flow with solid-liquid two-phase media inside centrifugal pumps is very complicated and the relevant method for the hydraulic design is still immature so far. There exist two main problems in the operation of the two-phase flow pumps, i.e., low overall efficiency and severe abrasion. In this study, the three-dimensional, steady, incompressible, and turbulent solid-liquid two-phase flows in a low-specific-speed centrifugal pump are numerically simulated and analyzed by using a computational fluid dynamics (CFD) code based on the mixture model of the two-phase flow and the RNG k- ɛ two-equation turbulence model, in which the influences of rotation and curvature are fully taken into account. The coupling between impeller and volute is implemented by means of the frozen rotor method. The simulation results predicted indicate that the solid phase properties in two-phase flow, especially the concentration, the particle diameter and the density, have strong effects on the hydraulic performance of the pump. Both the pump head and the efficiency are reduced with increasing particle diameter or concentration. However, the effect of particle density on the performance is relatively minor. An obvious jet-wake flow structure is presented near the volute tongue and becomes more remarkable with increasing solid phase concentration. The suction side of the blade is subject to much more severe abrasion than the pressure side. The obtained results preliminarily reveal the characteristics of solid-liquid two-phase flow in the centrifugal pump, and are helpful for improvement and empirical correction in the hydraulic design of centrifugal pumps.

  11. Measurement of group velocity dispersion in a solid-core photonic crystal fiber filled with a nematic liquid crystal. (United States)

    Wahle, Markus; Kitzerow, Heinz


    Liquid crystal-filled photonic crystal fibers (PCFs) are promising candidates for electrically tunable integrated photonic devices. In this Letter, we present group velocity measurements on such fibers. A large mode area PCF, LMA8, was infiltrated with the liquid crystal mixture, E7. The measurements were performed with an interferometric setup. The fiber exhibits several spectral transmission windows in the visible wavelength regime that originate from the bandgap guiding mechanism. The dispersion of these windows is very unusual compared to typical fibers. Our measurements show that it can change from -2500 ps km(-1) nm(-1) to +2500 ps km(-1) nm(-1) within a spectral range of only 15 nm. This leads to multiple zero dispersion wavelengths in the visible wavelength range.

  12. Binary Solid-Liquid Phase Diagram of Phenol and t-Butanol: An Undergraduate Physical Chemistry Experiment (United States)

    Xu, Xinhua; Wang, Xiaogang; Wu, Meifen


    The determination of the solid-liquid phase diagram of a binary system is always used as an experiment in the undergraduate physical chemistry laboratory courses. However, most phase diagrams investigated in the lab are simple eutectic ones, despite the fact that complex binary solid-liquid phase diagrams are more common. In this article, the…

  13. Extraction of Pb2+ using Silica from Rice Husks Ash (RHA – Chitosan as Solid Phase

    Directory of Open Access Journals (Sweden)

    Hanandayu Widwiastuti


    Full Text Available The existence of lead (Pb compounds in waters can be caused of waste pollution from industrial activities such as dye and battery industries. Lead has toxic characteristic and is able to causing deseases. The levels of Cr(VI can be decreased by methods such as electroplating, oxidation, reduction, and membrane separation. But this methods require high cost and produce a lot of waste. Furthermore, those methods cannot determine the small concentration of Pb2+. Therefore, solid phase extraction is used because it’s a simple method and can be used to preconcentrate Pb2+ ion. The aim of this study is to create solid phase from nature material as an alternative method to determine Pb2+ in water samples. The solid phase is silica from rice husks ash (RHA that was modified using chitosan. To achieve that aim, the optimization of silica : chitosan composition was done. The influence of Pb2+ concentration and citric acid concentration was studied to obtain optimum recovery of Pb2+. Interaction between Pb2+ ion and solid phase silica – chitosan could be estimated based on the result. The result showed the optimum composition of silica : chitosan is 65% silica : 35% chitosan with Cation Exchange Capacity (CEC 0.00455 mek/g. Mass Adsorbed Pb2+for 1 g silica : chitosan 65% is 9.715 mg/g. Optimum recovery of Pb2+ on solid phase extraction is reached at concentration of Pb2+ 10 ppm and citric acid concentration 0.05 M (88.25 % and 81.18 %. This result showed that solid phase extraction using silica – chitosan can be used as an alternative method to determine Pb2+ in water.

  14. Crystal Structure and Magnetic Anisotropy in the Magnetic Ordered Phases of PrB6 (United States)

    Sera, Masafumi; Kim, Moo-Sung; Tou, Hideki; Kunii, Satoru


    We have studied the magnetization and the thermal expansion of PrB6 in both C and IC phases. In the IC phase, the crystal is found to be nearly cubic. This is because the magnitude of av is different from site to site in the IC phase. In the C phase, the crystal is easily deformed into the diamond shaped one by a small external field such as a magnetic field or a uniaxial stress along the two-fold axis. This indicates the small AFQ interaction in PrB6. The magnetization exhibits the anisotropy, M>M>M in the IC phase and M>M>M in the C phase. The former is explained by a difference of the domain distribution for three field directions, i.e., the larger the population of the χ\\bot configuration, the larger the magnitude of M. In the C phase, the planer type Kxy domain state and the χ\\bot configuration are realized for three magnetic field directions. For H\\parallel and , the 1-k collinear magnetic structure is realized and the moment is rotated in the xy plane, while for H\\parallel, the moment is canted towards z axis from the xy plane. Altough in both cases, χ\\bot is associated with the Zeeman energy gain, χ\\bot in the former is smaller than that in the latter. This difference makes the anisotropy of M in the C phase as M>M>M.

  15. Separation of primary solid phases from Al-Si alloy melts

    Directory of Open Access Journals (Sweden)

    Ki Young Kim


    Full Text Available The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical, physical and chemical properties of the alloys should be removed. On the other hand, Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process. One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts. This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation, draining, filtration, electromagnetic separation and centrifugal separation, focused on the iron removal and on the separation of silicon in the solvent refining process.

  16. A High-Rate, Single-Crystal Model including Phase Transformations, Plastic Slip, and Twinning

    Energy Technology Data Exchange (ETDEWEB)

    Addessio, Francis L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bronkhorst, Curt Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Bolme, Cynthia Anne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Explosive Science and Shock Physics Division; Brown, Donald William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Cerreta, Ellen Kathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lebensohn, Ricardo A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Lookman, Turab [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Luscher, Darby Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Mayeur, Jason Rhea [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Morrow, Benjamin M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Materials Science and Technology Division; Rigg, Paulo A. [Washington State Univ., Pullman, WA (United States). Dept. of Physics. Inst. for Shock Physics


    An anisotropic, rate-­dependent, single-­crystal approach for modeling materials under the conditions of high strain rates and pressures is provided. The model includes the effects of large deformations, nonlinear elasticity, phase transformations, and plastic slip and twinning. It is envisioned that the model may be used to examine these coupled effects on the local deformation of materials that are subjected to ballistic impact or explosive loading. The model is formulated using a multiplicative decomposition of the deformation gradient. A plate impact experiment on a multi-­crystal sample of titanium was conducted. The particle velocities at the back surface of three crystal orientations relative to the direction of impact were measured. Molecular dynamics simulations were conducted to investigate the details of the high-­rate deformation and pursue issues related to the phase transformation for titanium. Simulations using the single crystal model were conducted and compared to the high-­rate experimental data for the impact loaded single crystals. The model was found to capture the features of the experiments.

  17. Visualization of membrane protein crystals in lipid cubic phase using X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Anna J. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Armour, Wes [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Oxford e-Research Centre, 7 Keble Road, Oxford OX1 3QG (United Kingdom); Axford, Danny; Basham, Mark; Connolley, Thomas; Hall, David R. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Horrell, Sam [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); University of Liverpool, Liverpool L69 3BX (United Kingdom); McAuley, Katherine E.; Mykhaylyk, Vitaliy; Wagner, Armin; Evans, Gwyndaf, E-mail: [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)


    A comparison of X-ray diffraction and radiographic techniques for the location and characterization of protein crystals is demonstrated on membrane protein crystals mounted within lipid cubic phase material. The focus in macromolecular crystallography is moving towards even more challenging target proteins that often crystallize on much smaller scales and are frequently mounted in opaque or highly refractive materials. It is therefore essential that X-ray beamline technology develops in parallel to accommodate such difficult samples. In this paper, the use of X-ray microradiography and microtomography is reported as a tool for crystal visualization, location and characterization on the macromolecular crystallography beamlines at the Diamond Light Source. The technique is particularly useful for microcrystals and for crystals mounted in opaque materials such as lipid cubic phase. X-ray diffraction raster scanning can be used in combination with radiography to allow informed decision-making at the beamline prior to diffraction data collection. It is demonstrated that the X-ray dose required for a full tomography measurement is similar to that for a diffraction grid-scan, but for sample location and shape estimation alone just a few radiographic projections may be required.

  18. Crystallization history of lunar picritic basalt sample 12002 - Phase-equilibria and cooling-rate studies (United States)

    Walker, D.; Kirkpatrick, R. J.; Longhi, J.; Hays, J. F.


    Experimental crystallization of a lunar picrite composition (sample 12002) at controlled linear cooling rates produces systematic changes in the temperature at which crystalline phases appear, in the texture, and in crystal morphology as a function of cooling rate. Phases crystallize in the order olivine, chromium spinel, pyroxene, plagioclase, and ilmenite during equilibrium crystallization, but ilmenite and plagioclase reverse their order of appearance and silica crystallizes in the groundmass during controlled cooling experiments. The partition of iron and magnesium between olivine and liquid is independent of cooling rate, temperature, and pressure. Comparison of the olivine nucleation densities in the lunar sample and in the experiments indicates that the sample began cooling at about 1 deg C/hr. Pyroxene size, chemistry, and growth instability spacings, as well as groundmass coarseness, all suggest that the cooling rate subsequently decreased by as much as a factor of 10 or more. The porphyritic texture of this sample, then, is produced at a decreasing, rather than a discontinuously increasing, cooling rate.

  19. Triple phase boundary specific pathway analysis for quantitative characterization of solid oxide cell electrode microstructure

    DEFF Research Database (Denmark)

    Jørgensen, Peter Stanley; Ebbehøj, Søren Lyng; Hauch, Anne


    The density and percolation of Triple phase boundary sites are important quantities in analyzing microstructures of solid oxide fuel cell electrodes from tomography data. However, these measures do not provide descriptions of the quality of the TPB sites in terms of the length and radius of the p......The density and percolation of Triple phase boundary sites are important quantities in analyzing microstructures of solid oxide fuel cell electrodes from tomography data. However, these measures do not provide descriptions of the quality of the TPB sites in terms of the length and radius...

  20. A Convergent Solid-Phase Synthesis of Actinomycin Analogues - Towards Implementation of Double-Combinatorial Chemistry

    DEFF Research Database (Denmark)

    Tong, Glenn; Nielsen, John


    of peptide-aryl-peptide conjugates modeled upon natural actinomycins. The features of this method include the use of Fmoc solid-phase peptide synthesis, side-chain to side-chain cyclization on the solid phase, a chemoselective cleavage step and segment condensation. The synthetic scheme is consistent...... with the requirements for combinatorial synthesis and furthermore, the final segment condensation allows, for the first time, double-combinatorial chemistry to be performed where two combinatorial libraries can be reacted with each other. Copyright (C) 1996 Elsevier Science Ltd....

  1. Application of solid phase extraction procedures for rare earth elements determination in environmental samples. (United States)

    Pyrzynska, Krystyna; Kubiak, Anna; Wysocka, Irena


    Determination of rare earth elements in environmental samples requires often pre-concentration and separation step due to a low metal content and high concentration of the interfering matrix components. A solid phase extraction technique with different kind of solid sorbents offers a high enrichment factor, rapid phase separation and the possibility of its combination with various detection techniques used either in on-line or off-line mode. The recent developments in this area published over the last five years are presented and discussed in this paper. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Use of the 2-chlorotrityl chloride resin for microwave-assisted solid phase peptide synthesis. (United States)

    Ieronymaki, Matthaia; Androutsou, Maria Eleni; Pantelia, Anna; Friligou, Irene; Crisp, Molly; High, Kirsty; Penkman, Kirsty; Gatos, Dimitrios; Tselios, Theodore


    A fast and efficient microwave (MW)-assisted solid-phase peptide synthesis protocol using the 2-chlorotrityl chloride resin and the Fmoc/tBu methodology, has been developed. The established protocol combines the advantages of MW irradiation and the acid labile 2-chlorotrityl chloride resin. The effect of temperature during the MW irradiation, the degree of resin substitution during the coupling of the first amino acids and the rate of racemization for each amino acid were evaluated. The suggested solid phase methodology is applicable for orthogonal peptide synthesis and for the synthesis of cyclic peptides. © 2015 Wiley Periodicals, Inc.

  3. Solid-Phase Synthetic Route to Multiple Derivatives of a Fundamental Peptide Unit

    Directory of Open Access Journals (Sweden)

    Martin J. O’Donnell


    Full Text Available Amino acids are Nature’s combinatorial building blocks. When substituted on both the amino and carboxyl sides they become the basic scaffold present in all peptides and proteins. We report a solid-phase synthetic route to large combinatorial variations of this fundamental scaffold, extending the variety of substituted biomimetic molecules available to successfully implement the Distributed Drug Discovery (D3 project. In a single solid-phase sequence, compatible with basic amine substituents, three-point variation is performed at the amino acid a-carbon and the amino and carboxyl functionalities.

  4. Size-dependent and tunable crystallization of GeSbTe phase-change nanoparticles (United States)

    Chen, Bin; Ten Brink, Gert H.; Palasantzas, George; Kooi, Bart J.


    Chalcogenide-based nanostructured phase-change materials (PCMs) are considered promising building blocks for non-volatile memory due to their high write and read speeds, high data-storage density, and low power consumption. Top-down fabrication of PCM nanoparticles (NPs), however, often results in damage and deterioration of their useful properties. Gas-phase condensation based on magnetron sputtering offers an attractive and straightforward solution to continuously down-scale the PCMs into sub-lithographic sizes. Here we unprecedentedly present the size dependence of crystallization for Ge2Sb2Te5 (GST) NPs, whose production is currently highly challenging for chemical synthesis or top-down fabrication. Both amorphous and crystalline NPs have been produced with excellent size and composition control with average diameters varying between 8 and 17 nm. The size-dependent crystallization of these NPs was carefully analyzed through in-situ heating in a transmission electron microscope, where the crystallization temperatures (Tc) decrease when the NPs become smaller. Moreover, methane incorporation has been observed as an effective method to enhance the amorphous phase stability of the NPs. This work therefore elucidates that GST NPs synthesized by gas-phase condensation with tailored properties are promising alternatives in designing phase-change memories constrained by optical lithography limitations.

  5. Dynamics of the phase transition boundary in the presence of nucleation and growth of crystals (United States)

    Alexandrov, D. V.


    Nucleation and growth of crystals in a moving metastable layer of phase transition is analyzed theoretically. The integro-differential equations for the density distribution function and system metastability are solved analytically on the basis of a previously developed approach (Alexandrov and Malygin 2013 J. Phys. A: Math. Theor. 46 455101) in cases of the kinetic and diffusionally controlled regimes of crystal growth. The Weber-Volmer-Frenkel-Zel’dovich and Meirs nucleation kinetics are considered. It is shown that the phase transition boundary propagates with time as α\\sqrt{t}+\\varepsilon Z_1(t) , where Z_1(t)=β t7/2 and Z_1(t)=β t2 in cases of kinetic and diffusionally controlled growth regimes. The growth rate constants α and β as well as parameter ɛ are found analytically. The phase transition boundary in the presence of particle nucleation and growth moves slower than in cases without nucleation.

  6. Synthesis and crystal structure of the first Sc-Nb-O-N phases

    Energy Technology Data Exchange (ETDEWEB)

    Orthmann, Steven; Lerch, Martin [Institut fuer Chemie, Technische Universitaet Berlin (Germany)


    Synthesis of phase-pure materials in the system Sc-Nb-O-N is challenging. In this contribution we report on the preparation of the first scandium niobium oxide nitrides via reaction of water-saturated gaseous ammonia or an ammonia-oxygen mixture with amorphous scandium niobium oxides. Two new phases were obtained: rutile-type ScNb{sub 4}O{sub 7}N{sub 3}, which crystallizes in space group P4{sub 2}/mnm, and an anion-deficient fluorite-type Sc{sub 2}Nb(O,N,⬜){sub 6} phase crystallizing in space group Fm anti 3m. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Amelogenin Affects Brushite Crystal Morphology and Promotes Its Phase Transformation to Monetite

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Dongni; Ruan, Qichao; Tao, Jinhui; Lo, Jonathan; Nutt, Steven; Moradian-Oldak, Janet


    Amelogenin protein is involved in organized apatite crystallization during enamel formation. Brushite (CaHPO4·2H2O), which is one of the precursors for hydroxyapatite in in vitro mineralization, has been used for fabrication of biomaterials for hard tissue repair. In order to explore its potential application in biomimetic material synthesis, we studied the influence of amelogenin on brushite morphology and phase transformation to monetite. Our results show that amelogenin can adsorb onto surface of brushite, leading to the formation of layered structures on the (010) face. Amelogenin promoted the phase transformation of brushite into monetite (CaHPO4) in the dry state, presumably by interacting with crystalline water layers in brushite unit cell. Changes to the crystal morphology by amelogenin continued even after the phase transformation to monetite forming an organized nanotextured structure of nano-sticks resembling the bundle structure in enamel.

  8. Creating physically-based three-dimensional microstructures: Bridging phase-field and crystal plasticity models.

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hojun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Owen, Steven J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Abdeljawad, Fadi F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hanks, Byron [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Battaile, Corbett Chandler [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    In order to better incorporate microstructures in continuum scale models, we use a novel finite element (FE) meshing technique to generate three-dimensional polycrystalline aggregates from a phase field grain growth model of grain microstructures. The proposed meshing technique creates hexahedral FE meshes that capture smooth interfaces between adjacent grains. Three dimensional realizations of grain microstructures from the phase field model are used in crystal plasticity-finite element (CP-FE) simulations of polycrystalline a -iron. We show that the interface conformal meshes significantly reduce artificial stress localizations in voxelated meshes that exhibit the so-called "wedding cake" interfaces. This framework provides a direct link between two mesoscale models - phase field and crystal plasticity - and for the first time allows mechanics simulations of polycrystalline materials using three-dimensional hexahedral finite element meshes with realistic topological features.

  9. Ultrastructural localization of Charcot-Leyden crystal protein (lysophospholipase) to intracytoplasmic crystals in tumor cells of primary solid and papillary epithelial neoplasm of the pancreas. (United States)

    Dvorak, A M; Letourneau, L; Weller, P F; Ackerman, S J


    Charcot-Leyden crystals (CLC), composed of a single protein with lysophospholipase activity, have been traditionally associated with eosinophil-rich disorders. Atypically shaped and typical CLC were noted by electron microscopy in the surgical sample from a patient with solid and papillary epithelial neoplasm of the pancreas. This rare primary tumor of the pancreas with limited aggressive behavior also contained damaged and partially or completely degranulated eosinophils in the tumor stroma. We localized CLC protein by ultrastructural immunogold staining to the CLC within vacuolar structures and in vesicles of tumor cell cytoplasm as well as to the cytoplasm and nucleus of eosinophils in the tumor stroma. These findings provide evidence that epithelial tumor cells contain Charcot-Leyden crystal protein that most likely originates from tumor stroma eosinophils. Tumor stroma eosinophils have generally been associated with improved prognoses in a wide variety of epithelial neoplasms. The role of tumor CLC protein (lysophospholipase) in these settings deserves further investigation.

  10. Non-Resonant Magnetoelectric Energy Harvesting Utilizing Phase Transformation in Relaxor Ferroelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Peter Finkel


    Full Text Available Recent advances in phase transition transduction enabled the design of a non-resonant broadband mechanical energy harvester that is capable of delivering an energy density per cycle up to two orders of magnitude larger than resonant cantilever piezoelectric type generators. This was achieved in a [011] oriented and poled domain engineered relaxor ferroelectric single crystal, mechanically biased to a state just below the ferroelectric rhombohedral (FR-ferroelectric orthorhombic (FO phase transformation. Therefore, a small variation in an input parameter, e.g., electrical, mechanical, or thermal will generate a large output due to the significant polarization change associated with the transition. This idea was extended in the present work to design a non-resonant, multi-domain magnetoelectric composite hybrid harvester comprised of highly magnetostrictive alloy, [Fe81.4Ga18.6 (Galfenol or TbxDy1-xFe2 (Terfenol-D], and lead indium niobate–lead magnesium niobate–lead titanate (PIN-PMN-PT domain engineered relaxor ferroelectric single crystal. A small magnetic field applied to the coupled device causes the magnetostrictive element to expand, and the resulting stress forces the phase change in the relaxor ferroelectric single crystal. We have demonstrated high energy conversion in this magnetoelectric device by triggering the FR-FO transition in the single crystal by a small ac magnetic field in a broad frequency range that is important for multi-domain hybrid energy harvesting devices.

  11. Interfacial free energy adjustable phase field crystal model for homogeneous nucleation. (United States)

    Guo, Can; Wang, Jincheng; Wang, Zhijun; Li, Junjie; Guo, Yaolin; Huang, Yunhao


    To describe the homogeneous nucleation process, an interfacial free energy adjustable phase-field crystal model (IPFC) was proposed by reconstructing the energy functional of the original phase field crystal (PFC) methodology. Compared with the original PFC model, the additional interface term in the IPFC model effectively can adjust the magnitude of the interfacial free energy, but does not affect the equilibrium phase diagram and the interfacial energy anisotropy. The IPFC model overcame the limitation that the interfacial free energy of the original PFC model is much less than the theoretical results. Using the IPFC model, we investigated some basic issues in homogeneous nucleation. From the viewpoint of simulation, we proceeded with an in situ observation of the process of cluster fluctuation and obtained quite similar snapshots to colloidal crystallization experiments. We also counted the size distribution of crystal-like clusters and the nucleation rate. Our simulations show that the size distribution is independent of the evolution time, and the nucleation rate remains constant after a period of relaxation, which are consistent with experimental observations. The linear relation between logarithmic nucleation rate and reciprocal driving force also conforms to the steady state nucleation theory.

  12. Recent developments and future trends in solid phase microextraction techniques towards green analytical chemistry. (United States)

    Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek


    Solid phase microextraction find increasing applications in the sample preparation step before chromatographic determination of analytes in samples with a complex composition. These techniques allow for integrating several operations, such as sample collection, extraction, analyte enrichment above the detection limit of a given measuring instrument and the isolation of analytes from sample matrix. In this work the information about novel methodological and instrumental solutions in relation to different variants of solid phase extraction techniques, solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) and magnetic solid phase extraction (MSPE) is presented, including practical applications of these techniques and a critical discussion about their advantages and disadvantages. The proposed solutions fulfill the requirements resulting from the concept of sustainable development, and specifically from the implementation of green chemistry principles in analytical laboratories. Therefore, particular attention was paid to the description of possible uses of novel, selective stationary phases in extraction techniques, inter alia, polymeric ionic liquids, carbon nanotubes, and silica- and carbon-based sorbents. The methodological solutions, together with properly matched sampling devices for collecting analytes from samples with varying matrix composition, enable us to reduce the number of errors during the sample preparation prior to chromatographic analysis as well as to limit the negative impact of this analytical step on the natural environment and the health of laboratory employees. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Dynamics of mineral crystallization at inclusion-garnet interface from precipitated slab-derived fluid phase: first in-situ synchrotron x-ray measurements (United States)

    Malaspina, Nadia; Alvaro, Matteo; Campione, Marcello; Nestola, Fabrizio


    Remnants of the fluid phase at ultrahigh pressure (UHP) in subduction environments may be preserved as primary multiphase inclusions in UHP minerals. These inclusions are frequently hosted by minerals stable at mantle depths, such as garnet, and show the same textural features as fluid inclusions. The mineral infillings of the solid multiphase inclusions are generally assumed to have crystallized by precipitation from the solute load of dense supercritical fluids equilibrating with the host rock. Notwithstanding the validity of this assumption, the mode of crystallization of daughter minerals during precipitation within the inclusion and/or the mechanism of interaction between the fluid at supercritical conditions and the host mineral are still poorly understood from a crystallographic point of view. A case study is represented by garnet orthopyroxenites from the Maowu Ultramafic Complex (China) deriving from harzburgite precursors metasomatised at ~ 4 GPa, 750 °C by a silica- and incompatible trace element-rich fluid phase. This metasomatism produced poikilitic orthopyroxene and inclusion-rich garnet porphyroblasts. Solid multiphase primary inclusions in garnet display a size within a few tens of micrometers and negative crystal shapes. Infilling minerals (spinel: 10-20 vol.%; amphibole, chlorite, talc, mica: 80- 90 vol.%) occur with constant volume ratios and derive from trapped solute-rich aqueous fluids. To constrain the possible mode of precipitation of daughter minerals, we performed for the first time a single-crystal X-ray diffraction experiment by means of Synchrotron Radiation at DLS-Diamond Light Source. In combination with electron probe microanalyses, this measurement allowed the unique identification of each mineral phase and their reciprocal orientations. We demonstrated the epitaxial relationship between spinel and garnet and between some hydrous minerals. Epitaxy drives a first-stage nucleation of spinel under near-to-equilibrium conditions

  14. Nearly-analogue blazed phase grating using high birefringence liquid crystal (United States)

    Bennis, N.; Geday, M. A.; Quintana, X.; Cerrolaza, B.; Medialdea, D. P.; Spadło, A.; Dąbrowski, R.; Otón, J. M.


    Diffraction of liquid crystal gratings has been thoroughly studied for many applications such as diffraction optics, optical processing, and spectral analysis. In pure optical processing one varies the direction of propagation of light beam without any mechanical adjustment. In this work we propose a beam steering device using highly birefringent liquid crystal material. Using a highly birefringent material one can reduce the LC layer thickness needed to achieve 2π of phase modulation and thus reduce the fringing effect caused by deformation of the electric field at the edge of the pixel. Here, we present 1.5-µm thick, high-resolution diffraction grating with non-detectable fringing.

  15. An energy-stable convex splitting for the phase-field crystal equation

    KAUST Repository

    Vignal, P.


    Abstract The phase-field crystal equation, a parabolic, sixth-order and nonlinear partial differential equation, has generated considerable interest as a possible solution to problems arising in molecular dynamics. Nonetheless, solving this equation is not a trivial task, as energy dissipation and mass conservation need to be verified for the numerical solution to be valid. This work addresses these issues, and proposes a novel algorithm that guarantees mass conservation, unconditional energy stability and second-order accuracy in time. Numerical results validating our proofs are presented, and two and three dimensional simulations involving crystal growth are shown, highlighting the robustness of the method. © 2015 Elsevier Ltd.

  16. In Situ Crystallization of the Insoluble Anhydrite AII Phase in Graphene Pockets. (United States)

    Lehnert, Tibor; Kinyanjui, Michael K; Ladenburger, Anita; Rommel, Dimitri; Wörle, Katharina; Börrnert, Felix; Leopold, Kerstin; Kaiser, Ute


    Single-distilled water encapsulated in graphene pockets has been studied by aberration-corrected high-resolution transmission electron microscopy and electron energy loss spectroscopy at an acceleration voltage of 80 kV. Inside the graphene pockets, crystallization and in situ crystal growth are reported and identified as the insoluble AII phase of CaSO4 (anhydrite) in a quasi-two-dimensional system. Its formation condition is discussed with respect to the possible temperature and van der Waals pressure between the graphene sheets.

  17. Some effects of ice crystals on the FSSP measurements in mixed phase clouds

    Directory of Open Access Journals (Sweden)

    G. Febvre


    Full Text Available In this paper, we show that in mixed phase clouds, the presence of ice crystals may induce wrong FSSP 100 measurements interpretation especially in terms of particle size and subsequent bulk parameters. The presence of ice crystals is generally revealed by a bimodal feature of the particle size distribution (PSD. The combined measurements of the FSSP-100 and the Polar Nephelometer give a coherent description of the effect of the ice crystals on the FSSP-100 response. The FSSP-100 particle size distributions are characterized by a bimodal shape with a second mode peaked between 25 and 35 μm related to ice crystals. This feature is observed with the FSSP-100 at airspeed up to 200 m s−1 and with the FSSP-300 series. In order to assess the size calibration for clouds of ice crystals the response of the FSSP-100 probe has been numerically simulated using a light scattering model of randomly oriented hexagonal ice particles and assuming both smooth and rough crystal surfaces. The results suggest that the second mode, measured between 25 μm and 35 μm, does not necessarily represent true size responses but corresponds to bigger aspherical ice particles. According to simulation results, the sizing understatement would be neglected in the rough case but would be significant with the smooth case. Qualitatively, the Polar Nephelometer phase function suggests that the rough case is the more suitable to describe real crystals. Quantitatively, however, it is difficult to conclude. A review is made to explore different hypotheses explaining the occurrence of the second mode. However, previous cloud in situ measurements suggest that the FSSP-100 secondary mode, peaked in the range 25–35 μm, is likely to be due to the shattering of large ice crystals on the probe inlet. This finding is supported by the rather good relationship between the concentration of particles larger than 20 μm (hypothesized to be ice shattered-fragments measured by the

  18. Solid solution and amorphous phase in Ti–Nb–Ta–Mn systems synthesized by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar, C., E-mail: [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzman, P. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Parra, C. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bejar, L. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Morelia C.P. 58000, Michoacán (Mexico); Medina, A. [Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, C.P. 58000, Michoacán (Mexico); Guzman, D. [Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó (Chile)


    This work discusses the formation of Ti–30Nb–13Ta–xMn (x: 2, 4 and 6 wt%) solid solution by mechanical alloying using a shaker mill. A solid solution was formed after 15 h of milling and an amorphous phase was formed after 30 h of milling, according to X-ray diffraction results. Disappearance of strongest X-ray diffraction peaks of Nb, Ta and Mn indicated the formation of solid solution, while, X-ray diffraction patterns of powders milled for 30 h showed an amorphous hump with crystalline peaks in the angular range of 35–45° in 2θ. TEM image analysis showed the presence of nanocrystalline intermetallic compounds embedded in an amorphous matrix. Mn{sub 2}Ti, MnTi and NbTi{sub 4} intermetallic compounds were detected and revealed crystallites with size ranging from 3 to 20 nm. The Gibbs free energy for the formation of solid solution and amorphous phase of three ternary systems (Ti–Nb–Ta, Ti–Nb–Mn and Ti–Ta–Mn) was calculated using extended Miedema's model. Experimental and thermodynamic data confirmed that solid solution was first formed in the alloy with 6wt% Mn followed by the formation of an amorphous phase as milling time increases. The presence of Mn promoted the formation of amorphous phase because the atomic radius difference between Mn with Ti, Nb and Ta. - Highlights: • Thermodynamics analysis of extension of solid solution of the Ti–Nb–Ta–Mn system. • Formation of amorphous phase and intermetallic compounds were observed. • Nanocrystalline intermetallic compounds were formed with the sizes between 3 and 20 nm.

  19. Liquid crystal phase transitions in systems of colloidal platelets with bimodal shape distribution. (United States)

    Verhoeff, A A; Wensink, H H; Vis, M; Jackson, G; Lekkerkerker, H N W


    We have studied a system of polydisperse, charged colloidal gibbsite platelets with a bimodal distribution in the particle aspect ratio. We observe a density inversion of the coexisting isotropic and nematic phases as well as a three-phase equilibrium involving a lower density nematic phase, an isotropic phase of intermediate density, and a higher density columnar phase. To relate these phenomena to the bimodality of the shape distribution, we have calculated the liquid crystal phase behavior of binary mixtures of thick and thin hard platelets for various thickness ratios. The predictions are based on the Onsager-Parsons theory for the isotropic-nematic (I-N) transition combined with a modified Lennard-Jones-Devonshire cell theory for the columnar (C) state. For sufficiently large thickness ratios, the phase diagram features an I-N density inversion and triphasic I-N-C equilibrium, in agreement with experiment. The density inversion can be attributed to a marked shape fractionation among the coexisting phases with the thick species accumulating in the isotropic phase. At high concentrations, the theory predicts a coexistence between two columnar phases with distinctly different concentrations. In experiment, however, the demixing transition is pre-empted by a transition to a kinetically arrested, glassy state with structural features resembling a columnar phase.

  20. Chiral liquid crystals: the vestigial chiral phases of T, O, I matter (United States)

    Nissinen, Jaakko; Liu, Ke; Slager, Robert-Jan; Wu, Kai; Zaanen, Jan

    We show how chiral order develops in vestigial isotropic phases of T , O and I liquid crystalline systems in three dimensions. The liquid crystal phases are realized in a lattice model of orientational degrees of freedom with point group symmetries G ⊂ O (3) , represented as O (3) -rotors coupled to G gauge fields. The model incorporates also disclinations via the gauge fields, features an ordered nematic phase with unbroken G rotations at low temperatures and a high temperature isotropic liquid phase. We observe an intermediate phase with spontaneous chirality but isotropic SO (3) symmetry (a liquid) for the gauge groups T, O, and I, the proper symmetry groups of the tetrahedron, cube and icosahedron, respectively. For the other subgroups of SO (3) , Cn <= ∞ and Dn <= ∞, there is generically only a single phase transition from the nematic phase to the isotropic liquid. We discuss the nature of the phase transitions and conditions under which the chiral phase is stabilized by the nematic order parameter fluctuations. The nature of the vestigial chiral phase is reminiscent of the so-called Ising nematic phase in iron based superconductors. Research supported by the Netherlands foundation for Fundamental Research of Matter (FOM).

  1. Drastic lowering of the order-disorder phase transition temperatures in Zr1-xMxW2O8-y(M=Sc,Y,In) solid solutions (United States)

    Yamamura, Yasuhisa; Nakajima, Noriyuki; Tsuji, Toshihide; Kojima, Ayumi; Kuroiwa, Yoshihiro; Sawada, Akikatsu; Aoyagi, Shinobu; Kasatani, Hirofumi


    ZrW2O8 undergoes an order-disorder phase transition associated with the orientational disordering of the WO4 tetrahedra at 440K . We have showed previously that the phase transition temperatures of Zr1-xMxW2O8-y(M=Sc,Y,In) solid solutions are decreased by a maximum of 80K with only 4% trivalent Sc content. In order to understand the drastic composition dependence on the transition temperature, precise x-ray diffraction experiments on the solid solutions were performed by using a synchrotron radiation. The results provided the evidence of the strong correlation between the phase transition temperature and the number of WO4 units with the ordered orientation. A model was proposed to interpret the drastic composition dependence on the transition temperature, by considering the existence of a local region including the WO4 pairs with the orientational disorder in Zr1-xMxW2O8-y(M=Sc,Y,In) . The local region has the crystal structure of the high-temperature phase in a nonequilibrium state, and spreads out around the substituted trivalent cations. The size of the local region was estimated to be a few unit cells. The local regions play just like nonmagnetic impurities in a site-diluted magnetic system, leading to drastic lowering of the phase transition temperatures in Zr1-xMxW2O8-y solid solutions.

  2. Solid-phase microextraction for the enantiomeric analysis of flavors in beverages. (United States)

    Ebeler, S E; Sun, G M; Datta, M; Stremple, P; Vickers, A K


    Solid-phase microextraction combined with gas chromatographic/mass spectrometric analysis and separation on a chiral cyclodextrin stationary phase was a rapid, reliable technique for profiling chiral aroma compounds in flavored alcoholic beverages. Several enantiomeric terpenes, esters, alcohols, norisoprenoids, and lactones were identified in berry-, peach-, strawberry-, and citrus-flavored wine and malt beverages (wine coolers). Using this technique, we were able to confirm the addition of synthetic flavoring to several beverages, consistent with label designations.

  3. Influence of copolymer composition on the phase behavior of solid dispersions. (United States)

    Prudic, Anke; Kleetz, Tobias; Korf, Marcel; Ji, Yuanhui; Sadowski, Gabriele


    The incorporation of poorly soluble active pharmaceutical ingredients (APIs) into excipients (e.g., polymers) to formulate an amorphous solid dispersion is a promising strategy to improve the oral bioavailability of the API. The application of copolymer excipients allows access to combinations of different monomers and thus to the design of excipients to improve solid-dispersion properties. In this work, the thermodynamic phase behavior of solid dispersions was investigated as a function of the API, type of monomer, and copolymer composition. The glass-transition temperatures and API solubilities in the solid dispersions of naproxen and indomethacin in polyvinylpyrrolidone, polyvinyl acetate, and copolymers with different weight fractions of vinylpyrrolidone and vinyl actetate were investigated. It is shown that the thermodynamic phase behavior of API/copolymer solid dispersions is a function of monomer type and copolymer composition. This effect was also predicted by using the perturbed-chain statistical associating fluid theory (PC-SAFT). The glass-transition temperature of the solid dispersions was calculated with the Gordon-Taylor equation.

  4. A simple and traceless solid phase method simplifies the assembly of large peptides and the access to challenging proteins. (United States)

    Ollivier, N; Desmet, R; Drobecq, H; Blanpain, A; Boll, E; Leclercq, B; Mougel, A; Vicogne, J; Melnyk, O


    Chemical protein synthesis gives access to well-defined native or modified proteins that are useful for studying protein structure and function. The majority of proteins synthesized up to now have been produced using native chemical ligation (NCL) in solution. Although there are significant advantages to assembling large peptides or proteins by solid phase ligation, reports of such approaches are rare. We report a novel solid phase method for protein synthesis which relies on the chemistry of the acetoacetyl group and ketoxime ligation for the attachment of the peptide to the solid support, and on a tandem transoximation/rearrangement process for the detachment of the target protein. Importantly, we show that the combination of solid phase and solution ligation techniques facilitates the production of a challenging and biologically active protein made of 180 amino acids. We show also that the solid phase method enables the purification of complex peptide segments through a chemoselective solid phase capture/release approach.


    Directory of Open Access Journals (Sweden)



    Full Text Available The dielectric properties of (PbySn1-y2P2(SexS1-x6 mixed crystals in the vicinity of the incommensurate phase transition have been studied. It has been found that due to the defect action, the dielectric anomalies at the phase transitions are smeared and instead of two anomalies bounding the incommensurate phase there is observed a single broad peak. The character of the dielectric dispersion as well as nonlinear dielectric behavior in the crystals studied suggest that in the chaotic state due to the action of the defect on the IC phase, the crystals possess the properties of ferroelectrics relaxors.

  6. Coronagraph Focal-Plane Phase Masks Based on Photonic Crystal Technology: Recent Progress and Observational Strategy (United States)

    Murakami, Naoshi; Nishikawa, Jun; Sakamoto, Moritsugu; Ise, Akitoshi; Oka, Kazuhiko; Baba, Naoshi; Murakami, Hiroshi; Tamura, Motohide; Traub, Wesley A.; Mawet, Dimitri; hide


    Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs.

  7. Optimization of solid phase microextraction coatings for liquid chromatography mass spectrometry determination of neurotransmitters. (United States)

    Cudjoe, Erasmus; Pawliszyn, Janusz


    A simple solid phase microextraction method coupled to liquid chromatography mass spectrometry is introduced for the analysis of neurotransmitter compounds with a wide range of polarities in biological matrices. A novel "reversed" reverse-phase chromatographic method was developed without pre-column derivatization for the analysis of dopamine, serotonin, gamma aminobutyric acid and glutamate. New solid phase microextraction "in house" coatings using mixed-mode solid phase extraction particles were prepared, and used for the extraction of polar neurotransmitters. The polymer-support base reverse phase mixed-mode sorbents with strong ion exchange properties generally had higher extraction efficiencies compared to similar sorbents with weak ion exchange properties. The linear range was determined to be between 0.01 and 150ng/mL for all the analytes, except for GABA, which was from 0.1 to 100ng/mL. The limit of detection range was from 6 to 10pg/mL for all the neurotransmitters, and the limits of quantitation were in the range of 20-35pg/mL. The results demonstrate the potential of the SPME-LC-MS/MS technique for bioanalysis of small polar endogenous compounds, such as neurotransmitters, from various biological matrices using the mixed-mode sorbents as the extraction phase. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Thermally-induced phase transition of pseudorotaxane crystals: changes in conformation and interaction of the molecules and optical properties of the crystals. (United States)

    Horie, Masaki; Suzaki, Yuji; Hashizume, Daisuke; Abe, Tomoko; Wu, Tiendi; Sassa, Takafumi; Hosokai, Takuya; Osakada, Kohtaro


    This paper presents a pseudorotaxane that acts as a thermally driven molecular switch in the single-crystal state. Crystals of the cationic pseudorotaxane consisting of dibenzo[24]crown-8 (DB24C8) and N-(xylylammonium)-methylferrocene as the cyclic and axle component molecules, respectively, undergo crystalline-phase transition at 128 °C with heating and 116 °C with cooling, according to differential-scanning-calorimetry measurements. X-ray crystallographic analyses revealed that the phase transition was accompanied by rotation of the 4-methylphenyl group of the axle component molecule and a simultaneous shift in the position of the PF(6)(-) counteranion. Crystalline phase transition changes the conformation and position of the DB24C8 molecule relative to the ammonium cation partially; the interaction between the cyclic component and the PF(6)(-) anion in the crystal changes to a greater extent. Moreover, there are changes in the vibration angle (θ) and birefringence (Δn) on the (001) face of the crystal transitionally; θ is rotated by +12°, and Δn is decreased from 0.070 to 0.059 upon heating across the phase transition temperature. The phase transition and accompanying change in the optical properties of the crystal occur reversibly and repeatedly upon heating and cooling processes. The switching rotation of the aromatic plane of the molecule induces a change in the optical anisotropy of the crystal, which is regarded as a demonstration of a new type of optical crystal. Partial replacement of the PF(6)(-) anion with the bulkier AsF(6)(-) anion forms crystals with similar crystallographic parameters. An increase in the AsF(6)(-) content decreases the reversible-phase-transition temperature gradually down to 99 °C (T(end)) and 68 °C (T(exo)) ([AsF(6)(-)]:[PF(6)(-)] = 0.4:0.6).

  9. Total solid-phase synthesis of the azathiocoraline class of symmetric bicyclic peptides. (United States)

    Bayó-Puxan, Núria; Fernández, Ariadna; Tulla-Puche, Judit; Riego, Estela; Cuevas, Carmen; Alvarez, Mercedes; Albericio, Fernando


    Thiocoraline is a potent antitumor agent isolated from the marine organism Micromonospora sp. This symmetric bicyclic depsipeptide binds the minor groove of DNA. Here we report two solid-phase strategies for the syntheses of azathiocoraline and its analogues. The thioester linkage was replaced by an amide bond to improve the compound's pharmacokinetic properties. The first strategy is based on a convergent (4+4) approach, whilst the second is a stepwise synthesis, cyclizations in both approaches occurring on the solid support. These two strategies were designed to overcome problems caused by the presence of consecutive noncommercial N-methyl amino acids, to avoid epimerization during cyclization and/or fragment condensation, and to form the disulfide bridge under solid-phase conditions. The heterocyclic moiety was added in the last step of the synthesis to assist the preparation of libraries of new compounds with potential therapeutic applications.

  10. Advances in automatic, manual and microwave-assisted solid-phase peptide synthesis. (United States)

    Sabatino, Giuseppina; Papini, Anna M


    Solid-phase strategies speed up the production of both short- and long-sequence peptides compared with solution methodologies. Therefore, solid-phase peptide synthesis (SPPS), proposed by Merrifield in the early 1960s, contributed to the 'Peptide Revolution' in the fields of diagnostics, and drug and vaccine development. Since then, peptide chemistry research has aimed to optimize these synthetic procedures, focusing on areas such as amide bond formation (the coupling step), solid supports and automation. Particular attention was devoted to the environmental impact of SPPS: the requirement for large amounts of organic solvents meant high costs for industrial peptide manufacturing that needed to be reduced. SPPS, alone or in hybrid technologies, has become strategic for the production of peptides as active pharmaceutical ingredients on a commercial scale.

  11. Fibers coated with molecularly imprinted polymers for solid-phase microextraction

    NARCIS (Netherlands)

    Koster, E.H M; Crescenzi, C; den Hoedt, W; Ensing, K; de Jong, G.J.


    The simplicity and flexibility of solid-phase microextraction have been combined with the selectivity of molecularly imprinted polymers (MIPs), Silica fibers were coated reproducible with a 75-mum layer of methacrylate polymer either nonimprinted or imprinted with clenbuterol to compare their

  12. Crystalline CoFeB/graphite interfaces for carbon spintronics fabricated by solid phase epitaxy

    NARCIS (Netherlands)

    Wong, P.K.J.; van Geijn, Elmer; van Geijn, E.; Zhang, W.; Starikov, A.A.; Tran, T. Lan Ahn; Sanderink, Johannes G.M.; Siekman, Martin Herman; Brocks, Gerardus H.L.A.; Kelly, Paul J.; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter


    Structurally ordered interfaces between ferromagnetic electrodes and graphene or graphite are of great interest for carbon spintronics, since they allow spin-filtering due to k-vector conservation. By solid phase epitaxy of amorphous/nanocrystalline CoFeB at elevated temperatures, the feasibility of

  13. Optimization of in-line fritless solid-phase extraction for capillary electrophoresis-mass spectrometry

    NARCIS (Netherlands)

    Tak, Yvonne H.; Toraño, Javier Sastre; Somsen, Govert W.; de Jong, Gerhardus J.


    In this study, in-line frit-free solid-phase extraction (SPE) has been studied for the preconcentration of analytes prior to analysis by capillary electrophoresis-mass spectrometry (CE-MS). The mixed-mode sorbent Oasis HLB was selected for the trapping of compounds of different polarity. Using


    This presentation focuses on the development of a solid-phase microextraction (SPME)-gas chromatography (GC)/ion trap mass spectrometry (MS) method for the analysis of semivolatile disinfection by-products (DBPs) in drinking water in the low ug/L range. These DBPs were selected ...

  15. Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME)

    NARCIS (Netherlands)

    Benhabib, K.; Town, R.M.; Leeuwen, van H.P.


    Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the

  16. Headspace analysis of polar organic compounds in biological matrixes using solid phase microextraction (SPME) (United States)

    Analysis of biological fluids and waste material is difficult and tedious given the sample matrix. A rapid automated method for the determination of volatile fatty acids and phenolic and indole compounds was developed using a multipurpose sampler (MPS) with solid phase microextraction (SPME) and GC-...

  17. Solid-phase synthesis of succinylhydroxamate peptides : Functionalized matrix metalloproteinase inhibitors

    NARCIS (Netherlands)

    Leeuwenburgh, M.A.; Geurink, P.P.; Klein, T; Kauffman, H.F; van der Marel, G.A.; Bischoff, Rainer; Overkleeft, H.S.


    A novel solid-phase synthesis strategy toward succinylhydroxamate peptides, using an appropriately protected hydroxamate building block, is described. Rapid and efficient access is gained to amine-functionalized peptides, which can be decorated with, for instance, a fluorescent label. In addition,

  18. Determination of phenols in landfill leachate-contaminated groundwaters by solid-phase extraction

    DEFF Research Database (Denmark)

    Ask Reitzel, Lotte; Ledin, Anna


    A solid-phase extraction method for phenols in landfill leachates was developed and optimized in order to solve the expected and observed problems associated with an anaerobic matrix containing high concentrations of salts and organic matter. Isolute ENV1 cartridges exhibited the best retention...

  19. Solid Phase Immunoassay Using Immunoreagents Immobilized on Inert Synthetic Resin Surfaces

    NARCIS (Netherlands)

    Hummelen, Jan C.; Luider, Theo; Wynberg, Hans


    A solid phase immunoassay comprises the steps of (a) immobilizing an immunoreagent on the surface of a carrier comprised of an inert synthetic resin selected from the group consisting of polyimides and polyfluorinated synthetic resins, (b) contacting the immunoreagent with a complementary

  20. Highly Selective Liquid-Phase Benzylation of Anisole with Solid-Acid Zeolite Catalysts

    DEFF Research Database (Denmark)

    Poreddy, Raju; Shunmugavel, Saravanamurugan; Riisager, Anders


    Zeolites were evaluated as solid acid catalysts for the liquid-phase benzylation of anisole with benzyl alcohol, benzyl bromide, and benzyl chloride at 80 °C. Among the examined zeolites, H-mordenite-10 (H-MOR-10) demonstrated particular high activity (>99 %) and excellent selectivity (>96...